The branch, tex4htTesting, has been updated. - Log -----------------------------------------------------------------
commit 32bb3609197b3422fb987980536e2020e3439521 Author: Prannoy Pilligundla <prannoy.b...@gmail.com> Date: Tue Aug 5 00:17:59 2014 +0530 Added the tex file for the previous commit. Run "mk4ht ooxelatex PS_Report_Final.tex imageconv.cfg" for the conversion diff --git a/tests/PS_Report_Final.tex b/tests/PS_Report_Final.tex new file mode 100644 index 0000000..11e1d3b --- /dev/null +++ b/tests/PS_Report_Final.tex @@ -0,0 +1,1111 @@ +%% LyX 2.1.0dev created this file. For more info, see http://www.lyx.org/. +%% Do not edit unless you really know what you are doing. +\documentclass[english]{report} +\usepackage[T1]{fontenc} +\setcounter{secnumdepth}{3} +\setcounter{tocdepth}{3} +\usepackage{graphicx} +\usepackage{subscript} +\usepackage{babel} +\begin{document} + +\title{Implementing PLC based system in Upgrading Plant} + + +\author{Prannoy Pilligundla 2012A8PS264P\\ +Siddarth Singh 2012AAPS823P\\ +Vineet Cherian 2012A3PS015P} + +\maketitle +\tableofcontents +\begin{abstract} +Heavy water which is used a moderator in a PHWR is often contaminated +with some chemical impurities and Light water. The chemical impurities +like corrosion products, oil, dirt etc are removed from the downgraded +Heavy water in the cleanup system before sending it to Upgrading plant +for further processing. Basis of seperation of Heavy water and Light +water is the difference in Boiling point of 1.41\textsuperscript{o}C. +Upgrading is done by the continuous distillation under sub-atmospheric +condition. The downgraded heavy water is boiled in a reboiler and +made to ascend through the packed distillation column. It is condensed +at the top in the reflux condensor and the condensed liquid is putback +at the top of the tower as reflux. The vapour ascending and liquid +descending will come in intimate contact in tower section. Due to +this mass transfer takes place. Ligher component H\textsubscript{2}O +is transferred to the vapour phase from liquid phase. The mass transfer +taking place in the tower sets up a concentration gradient throughout +the tower section. Thus at the bottom of the tower it will be pure +heavy water and at the top of the column it will be light water. The +process instrumentation logic is based on the philosophy of simple +and safe operation. Interlocks have been provided with process parameters +to trip the plant whenever unsafe conditions are developed. + +Our main objective here is to upgrade an existing relay based control +system with a Programmable Logic Controller(PLC) in this Heavy Water +Upgradation Plant +\end{abstract} +Heavy water which is used a moderator in a PHWR is often contaminated +with some chemical impurities and Light water. The chemical impurities +like corrosion products, oil, dirt etc are removed from the downgraded +Heavy water in the cleanup system before sending it to Upgrading plant +for further processing. Basis of seperation of Heavy water and Light +water is the difference in Boiling point of 1.41\textsuperscript{o}C. +Upgrading is done by the continuous distillation under sub-atmospheric +condition. The downgraded heavy water is boiled in a reboiler and +made to ascend through the packed distillation column. It is condensed +at the top in the reflux condensor and the condensed liquid is putback +at the top of the tower as reflux. The vapour ascending and liquid +descending will come in intimate contact in tower section. Due to +this mass transfer takes place. Ligher component H\textsubscript{2}O +is transferred to the vapour phase from liquid phase. The mass transfer +taking place in the tower sets up a concentration gradient throughout +the tower section. Thus at the bottom of the tower it will be pure +heavy water and at the top of the column it will be light water. The +process instrumentation logic is based on the philosophy of simple +and safe operation. Interlocks have been provided with process parameters +to trip the plant whenever unsafe conditions are developed. + + +\chapter{Upgrading Plant} + + +\section{Introduction} + +The Madras Atomic Power Station is designed of the CANDU type,almost +similar to the Rajasthan Atomic Power Station. The Nuclear reactor +is of natural Uranium, Heavy water moderated and cooled. This Heavy +Water gets depleted due to leakages in the system. These leakages +are mainly collected from fuelling machine vault, Primary heat transfer +system and boiler room. In the ``PHWR'' type of reactors heavy water +is used both as moderator and as heat transport fluid. Downgrading +of high quality water occurs through two mechanisms: +\begin{enumerate} +\item Light water leakage into the heavy water system. +\item Heavy water escape from PHT and Moderator systems where it comes in +contact with light water +\end{enumerate} +Downgraded D\textsubscript{2}O is a mixture of light water, D\textsubscript{2}O +and other solid and chemical impurities. The downgraded heavy water +containing various chemical impurities render the heavy water unfit +for use without further processing. The chemical impurities like corrosion +products, oil, dirt etc are removed from the downgraded heavy water +in the clean up system before sending it to the upgrading plant for +further processing. The chemical purity should be strictly followed +before processing the downgraded heavy water in the distillation plant. + +\emph{Design Capacity of Distillation Columns}: The distillation plant +has been designed to process 36 litres/hr of 60\%(w/w) and 36 litres/hr +of 30\%(w/w) for bottom product at 99.8\% D\textsubscript{2}O(w/w) +with top reject of 0.5\% D\textsubscript{2}O(w/w). Based on the above +performance data at 7800 operating hours oer year the annual plant +capacity is expected to be 250 tonnes of reactor grade Heavy Water. + + +\section{Distillation Processs} + + +\subsection{Principle of Operation} + +Heavy Water(D\textsubscript{2}O) and Light Water(H\textsubscript{2}O) +are alike in their chemical properties but differ in their physical +properties. At atmospheric pressure the boiling point of H\textsubscript{2}O +is 100\textsuperscript{o}C and boiling point of D\textsubscript{2}O +is 101.42\textsuperscript{o}C. Thus relative volatility ( Boiling +point difference i.e 1.42\textsuperscript{o}C) is basis for seperation +of D\textsubscript{2}O and H\textsubscript{2}O in the distillation +column. + +Upgrading is done by continuous distillation under sub atmospheric +condition. The downgraded heavy water is boiled in a reboiler and +made to ascend through the packed distillation column. It is condensed +at top in the reflux condenser and the condensed liquid is put back +at the top of the tower as reflux. The vapour ascending and liquid +descending will come in intimate contact in the tower section. Due +to this mass transfer takes place. Lighter component(H\textsubscript{2}O) +is transferred to the vapour phase from liquid phase. The mass tranfer +taking place in the tower sets up a concentration gradient throughout +the tower section. Thus at the bottom of the tower,it will be pure +heavy water and at the top of column it will be light water. + +Part of the reboiler vapour is taken as product and part of the condensed +liquid from the reflux condenser is collected as reject (IP â¤0.25\%w/w). +Depending on the feed concentration, feed is put into the tower at +some point along the height of the tower where the feed concentration +matches with the local concentration of the tower. + + +\subsection{Process} + +The principle of the distillation and equilibrium condition are mentioned +above. It takes nearly three days i.e 72 hours to achieve this equilibrium +condition. Feed in the form of vapour will be added at a point in +the column where its Isotopic Purity (I.P) matches with the column +section I.P. Reject is removed from the top as a liquid and product +is taken from the bottom. One important thing to be noticed is, the +equilibrium should not be disturbed at any condition. This is possible +if the feed rate is equal to the reject rate plus product rate. This +is given below as the material balance equation. + +\begin{equation} +F=P+R +\end{equation} + + +\[ +F=\mathrm{Feed}\: Rate\: in\: lit/hr +\] + + +\[ +P=Product\: Rate\; in\: lit/hr +\] + + +\[ +R=Reject\: rate\: in\: lit/hr +\] + + +Mole fraction or Component(D\textsubscript{2}O) balance is given +by + +\begin{equation} +FX_{F}=PX_{P}+RX_{R} +\end{equation} + + +\[ +X_{F}=D_{2}O\: fraction\: of\: feed +\] + + +\[ +X_{P}=D_{2}O\: fraction\: of\: feed +\] + + +\[ +X_{R}=D_{2}O\: fraction\: of\: Reject +\] + + +As per design, for a specified feed I.P the feed rate should not exceed +above a certain value. This is given in the table and also in the +graph. Product and Reject I.P's are as oer our requirements i.e reject +I.P<0.25\% and Product I.P>99.97\% for moderator grade and >99.4\% +for PHT grade liquid. Hence X\textsubscript{F},X\textsubscript{P},X\textsubscript{R} +and F are fixed. To find out the product and reject rates the above +two equations can be solved to get + +\begin{equation} +P=\frac{F(X_{F}-X_{R})}{(X_{P}-X_{R})} +\end{equation} + + +\begin{equation} +R=F-P +\end{equation} + + +For a distillation column the seperation factor achieved is 1.05. +Seperation factor is defined as follows: + +\[ +Seperation\: Factor=\frac{\frac{atom\: fraction\: of\: H_{2}}{atom\: fraction\: of\: D_{2}}\: in\: gas}{\quad\frac{atom\: fraction\: of\: H_{2}}{atom\: fraction\: of\: D_{2}}\: in\: liquid} +\] + + +The maximum attainable seperation factor is 1.05 as per design. To +achieve this the column pressure should be reduced. This pressure +cannot be reduced beyond a certain value because of the increase in +the specific volume of vapour which inturn leads to very high column +dimensions and inturn increases the column cost. Since the process +water temperature is limited around 33\textsuperscript{o}C, there +is always a lower limit on the temperature of the vapour which is +required to be cooled, so that efficient condensation can take place. +(This inturn means a low pressure restriction inside the column top, +which is 120mm of Hg absolute). Column sump pressure is around 230mm +of Hg.abs. + + +\subsection{Definitions} + + +\paragraph{Total Reflux} + +Total Reflux implies that there is no feed, no product, and reject +take off i.e 3493 CV-53, 3493 CV-272, 3493 CV-73 and 3493 CV-134 are +closed. + + +\paragraph{Shut down of the distillation column} + +In addition to the total reflux state, the reboiler steam control +CV-266 is also closed in this state. + + +\subsection{Specification of feed D\protect\textsubscript{2}O} +\begin{enumerate} +\item K ⤠5 micromho/cm or microsiemens/cm +\item PH 6.5 to 8 +\item Chloride ⤠0.5ppm +\item Nitrate ⤠1ppm +\item Oil Free +\item Particulate matter free +\item Organic materials ⤠10ppm ammonia and amines +\end{enumerate} + +\section{Equipment Description} + + +\subsection{Distillation Column} + +Distillation column consists of 14 identical sections with sump at +the bottom. At the top of the column reflux condenser CD-4 and a vent +condenser CD-5 are present to condense the vapours. Operating temperature +and pressure varies from 74\textsuperscript{o}C and 230mm Hg(abs)-at +column sump to 56\textsuperscript{o}C and 120mm Hg(abs) at the top. +Outside diameter and height of each column section is â2.5mm and 3200â3mm +respectively. Each column section is packed with corrugated phosphor +bronze wire mesh packing with a coating of copper oxide for surface +activation which increases wet surface. This packing is supported +by means of a bottom ring. The top support ring supports the liquid +distributor, which distributes the liquid evenly on the packing. Liquid +collector collects the downcoming liquid and puts it onto the distribution +without hindering the vapour flow. For the fourteenth section liquid +collector is not required + + +\subsection{Column Sump} + +Column sump at the bottom of the column holds the downcoming reflux +liquid from the distillation column and provides flooded suction to +the reboiler circulating pump. Capacity of the sump is decided on +the initial hold up required for flooding the distillation column. +This requirement is around 3 tonnes. + + +\subsection{Reboiler EV-2} + +A falling film type reboiler is provided for reboiling the reflux +liquid of the distillation tower. It is a shell and tube type 1-1Hx. +Liquid is pumped to the top of the tubesheet of the reboiler and falls +thorugh the tubes in the form of a film and is vapourised. The vapour +along with the liquid comes down from the bottom side and enters the +column sump. For getting a good heat transfer coefficient a 4.5:1 +circulation ratio is to be used. + +Special features of falling film reboiler are: +\begin{itemize} +\item High heat tranfer coefficient due to the turbulent film flowin tubes. +\item Low hold up because tubes are not completely filled. +\end{itemize} + +\subsection{Reflux Condenser(CD-4)} + +This is a 2-2 shell and tube Hx, cooled by process water, used to +condense the ascending vapours and to provide reflux to distillation +column. In the vapour hood portion an annular space serves as the +reflux drum, where condensate gets collected and overflows into the +distillation column. This reduces the reflux holdup considerably. +The temperature of the column at the reflux end is 55.3\textsuperscript{o}C. + + +\subsection{Feed Evaporator(EV-1)} + +It is a jacketed vessel with a surface area of 1.2Sq.m. Feed heavy +water is boiled in this vessel and is fed to the column in the vapour +form. Steam condenses in the jacket and goes to steam condensate collection +tank TK-15. + + +\subsection{Product Condenser(CD-2)} + +This is a 1:2 shell and tube type of Hx with a surface are of 5.5M\textsuperscript{2} +used to condensate the vapour form the collection sump which goes +down to the product tank TK-10. + + +\subsection{Vent Condenser(CD-5)} + +This is a 1:2 shell and tube condenser with a surface are of 3.6M\textsuperscript{2}which +condenses any vapour that escapes uncondensed from the reflux condenser. +Chilled water is used as the cooling media in this condenser. + + +\subsection{Exhaust Cooler(CD-1)} + +It is a 1:2 shell and tube type condenser used to trap any vapour +escaping from vacuum pump exhaust, feed tank and feed overflow tank +vent line. + + +\subsection{Product vent condenser CD-6 and Product tank vent cold trap CD-3} + +Both are of similar geometry and construction. CD-6 condenses the +escaping vapours from product condenser whereas CD-3 acts as a trap +for product tank TK-10 + + +\subsection{Water circulating tank TK-4 vacuum pump and cyclone seperators(TK-2 +\& TK-3)} + +To create and maintain vacuum at the distillation column two 100\% +capacity vacuum pumps are used. To provide cooling two 100\% capacity +vacuum pumps are used. To provide cooling water for these pumps at +the rate of 14lpm in a closed loop circulation arrangement, a water +circulating tank and two 100\% capacity pumps are provided. A chilled +water cooling arrangement is provided for cooling the seal liquid +TK-4. A cyclone separator is provided at the exhaust of each vacuum +pump to separate the seal water from the exhaust vapours going to +exhaust cooler thereby reducing the load on the exhaust cooler, \textsubscript{1}H\textsuperscript{3 }affinity +towards water is more and so it gets diluted with water and \textsubscript{1}H\textsuperscript{3} +free air which further cooled in CD-1 is sent out to atmosphere. + + +\subsection{Feed tank TK-5 \& TK-13} + +This tank stores the depleted D\textsubscript{2}O from the evaporation +clean up section. Capacity of these tanks are 3170 litres eac. This +is based on holding 48 hours feed at a time for the distillation tower. +The second tank is used to prepare feed stock when the first one is +in stream. + + +\subsection{Product storage tank TK-10} + +Reactor grade D\textsubscript{2}O is collected in this tank from +the distillation process. This is intermittently pump to drums and +sent to station whenever required. + + +\subsection{Reject storage tank TK-10} + +Reject containing ⤠0.25\% I.P liquid is collected in this tank and +then it is sent out to liquid effluent management plant(LEMP). + + +\subsection{Feed Overflow tank TK-6} + +This tank provides feed flow to the feed evaporator at constant head +which can be further controlled by a flow control loop arrangement +controlling CV-53. + + +\subsection{Buffer tank TK-1} + +This tank acts as a buffer in the vacuum system. + + +\subsection{Steam Condensate tank TK-15} + +This tank collects the steam condensate from evaporator EV-1 \& EV-2 +and puts back the condensates to deaerator for steam generation in +the boilers with the help of steam condensate pumps 4321-P-16 \& P-17. + + +\subsection{Product \& Reject overflow vessels TK-8 \& TK-9} + +These two graduated vessels have the following functions +\begin{enumerate} +\item To keep sufficient holdup of liquid to provide barometer head +\item To calibrate the product and reject flow through orifices. They are +provided with integral visual level gauges. +\end{enumerate} + +\subsection{Pumps} + +All pumps are used in the upgrading plant for D\textsubscript{2}O +service are canned motor pumps to attain zero leakage. + + +\subsection{Reboiler circulating pumps} + +These pumps provide circulation for falling film type reboiler EV-2. +Only one pump is operated at a time. The other pump will be standby. + + +\subsection{Feed, Product and Reject transfer pumps} + +These are $2\times100\%$ capacity. These are required for pumping +liquid from feed tanks to feed overflow tank TK-6. Product transfer +pump is used to transfer the reactor grade D\textsubscript{2}O from +product tank TK-10 to drums and reject transfer pump is used to pump +the water in reject tank TK-11 to LEMP. + + +\subsection{Cooling water pumps 7131-P9, P10, P-11} + +These are $2\times100\%$ capacity pumps used for boosting the pressure +of the cooling water to 9Kg/cm\textsuperscript{2} which is required +at the reflux condenser as per design. During plant startup both the +pumps can be run. + + +\subsection{Chilled water booster pumps 7192-P-5, P-6 \& P-7} + +These are 100\% capacity pumps. These pumps boost the chilled water +pressure required for the vent condenser and cold traps. + + +\section{Inter connection with other system} + + +\subsection{Steam Requirement} + +Approximately 5000Kg/hr of dry saturated steam at a pressure of 1.8Kg/cm\textsuperscript{2}is +required during the startup of distillation for flooding operation. +After some 3 to 4 hours during normal operation the requirement is +3400Kg/hr at a pressure of 1.8Kg/cm\textsuperscript{2}. + + +\subsection{Cooling Water Requirement} + +Cooling water requirement of 250M\textsuperscript{3}/hr at 9Kg/cm\textsuperscript{2}and +33\textsuperscript{o}C is required during normal operation for reflux +condenser and product condenser of both the distillation columns. +During flooding 400M\textsuperscript{3}/hr of process water will +be required for both the distillation columns. + + +\subsection{Chilled Water} + +Chilled water is required for vent condensers, vacuum pump assembly +and also for vent cold traps. 15M\textsuperscript{3}/hr of chilled +water at 9Kg/cm\textsuperscript{2}is required for the above chilled +water loads. + + +\subsection{Electrical Power} + +Power supply required for this plant is 400/400 volts, 3à HZ A.C 180 +KW. Installed capacity is 400KW. + + +\subsection{Instrument Air} + +Oil free, moisture free air at a pressure of 5.3Kg/cm\textsuperscript{2}is +required for pneumatic instruments. + + +\section{Interlocks \& Logics} + + +\subsection{Safety Interlocks} + +There are two conditions which can shutdown the plant. They are +\begin{itemize} +\item High temperature in vacuum line $50-G-93$ in CD-5 exit +\item Failure of vacuum which results in very high pressure alarm of vacuum +line $50-G-93$ +\end{itemize} +The following are the interlocks provided for pytting the column under +total reflux +\begin{itemize} +\item Low $\triangle P$ +\item Low flow in reboiler EV-2 i.e < 7M\textsuperscript{3}/hr +\item High temperature in CD-6(product vent condenser) i.e >25\textsuperscript{o}C +\end{itemize} +Hand switches, Indicators, Controllers for most of the equipments +covered in distillation process are in upgrading plant control room +located in first floor of upgrading plant. + + +\subsection{Feed Pump Hand Switch} + +Feed pump starts if there is no overload and emergency push button +is not pressed and HS is in ON position or HS is in auto 1 position +and low level in TK-5 is not existing or HS is in auto 2 position +and low level in TK-13 is not existing. Running feed pump stops if +overload exists or emergency push button is pressed or HS is kept +in auto 2 position and low level exists in TK-13 + + +\subsection{Feed Flow Control} + +Feed flow from feed overflow tank to feed evaporator is measured by +FE-12147 and this signal is fed through a FRC-12202 to control CV-53 +(Presently in MAPS, the feed flow is set and controlled by a rotameter) + + +\subsection{Feed Overflow tank level} + +Low level in this TK-6 will close CV-53. Alarm ``low level in TK-6'' +also comes in UGP control room. This TK-6 inventory is sufficient +to continue the operation of the distillation column for approximately +1 hour with the inflow to TK-6 is stopped + + +\subsection{Feed Evaporator (EV-1) level control loop} + +LT-12072 measures the EV-1 level and controls steam CV-272 through +a controller LIC-12005 so that the evaporator level is maintained. +This implies that whatever is the inflow to EV-1 from TK-6 will be +evaporated and fed to distillation column. + + +\subsection{Differential pressure control loop for the column} + +The performance of the distillation tower is very much dependent on +the pressure drop across the tower and on the boil up rate from reboiler. +A variation in boil up rate can vary the pressure drop across the +column. Hence, control on $\triangle P$ which is cascaded with the +steam pressure control in reboiler is used to control $\triangle P$ +across the column and boilup from reboiler. A larms are provided for +high and low $\triangle P$ in the column. A low $\triangle P$ will +put the column under total reflux. + + +\subsection{Vacuum Control Loop} + +PT-12045 senses the pressure at the buffer tank and controls CV-159 +such that 120mm of Hg absolute is maintained at the top of the column. +A bleed air facility with a 2 way solenoid valve is provided so that +CV-159 will operate well in its control range, if the air leak to +the process system is very small. Presetting of the bleed air is done +by a needle valve, which is in series with the solenoid valve + + +\subsection{Water circulating tank TK-4 level control} + +High level in TK-4 closes SV-12325 and stops DM water addition and +also it gives an alarm. Low level in TK-4 annunciates and also it +closes CV-159, stops bleed air flow, stop vacuum pumps and seal water +circulating pumps. LC-12007 level control provided keeps steady level +in TK-4 by supply make up water through SV-12325 + + +\subsection{Product and Reject withdrawal system} + + +\subsubsection{Column sump (TK-7) level control} + +This controls product (reject) flow through CV-73 (CV-134), if the +feed IP >50\% and HS-12327 is in High (Low) position. The lesser of +these two flow (Product \& Reject flows) is controlled by timer and +the larger of these two flows is controlled by column sump level control + +Flow restriction orifices in the product and reject lines which limit +the flow to 100Kg/hr + +Low sump level will stop product and reject withdrawal. High sump +level will cut off steam supply to feed evaporator + + +\subsubsection{Timer Circuit Control} + +The lower of the two product and reject withdrawal rate is controlled +by a timer circuit. If feed IP is less(more) than HS-12327 will be +low(high) and timer will control CV-73(CV-134). First timer gets energized +and opens the CV-73 (CV-134) for a certain period as determined in +the setting. When the first timer is timed out the second timer is +energized and this closes the CV-73 (CV-134). This continues in a +cyclic manner and hence maintains the rate of withdrawal of product +(Reject) + + +\subsection{Reboiler Circulation} + +High heat transfer is achieved if there is a turbulent to the film +flow in the tubes. If low flow is existing then running reboiler pump +trips and the plant will run under total reflux. Auto starting of +standby pump works only on over-load tripping of running pump if reboiler +circulation is less than 7M\textsuperscript{3}/hr. Then CV-266 will +be closed to safeguard EV-2 + + +\subsection{Steam Condensate tank TK-15 level control} + +Steam condensate pumps (2x100\% capacity) can be started/stopped manually. +In auto condition, these pumps start if tank level is high and stop +when TK-12 level is low. + + +\subsection{Instrument Air Pressure} + +Air supply pressure is 10Kg/sq.cm. If it is 100psi then air pressure +low alarm comes in UGP control room. + + +\subsection{Product and Reject Tank Level Control} + +Low level in these tanks trips the corresponding pumps low and high +level alarms are provided in upgrading plant control room + + +\chapter{Experimental Details and Concepts Involved} + + +\section{Programmable Logic Controller (PLC)} + + +\subsection{Introduction} + +A PLC (Programmable Logic Controller) is defined as a user-friendly, +microprocessor based specialized computer that carries out control +functions of many types and levels of complexity. The first PLC systems +evolved from conventional computers in the late 1960s and early 1970s. +These first PLCs were installed primarily in automotive plants. What +has taken months back then takes few days today. Many companies like +Allen-Bradley, Mitsubishi, and Siemens manufacture PLCs. In conventional +controllers the functions are determined by their physical wiring, +whereas the functions of PLCs are defined by a program. They are also +connected to other parts with cable , but the content of their program +memory can be changed at any time to adapt their programs to different +control tasks. + + +\subsection{Advantages of using PLC} +\begin{itemize} +\item Flexible +\item Faster response time +\item Simpler Wiring +\item Modular Design- easy to repair and expand +\item Handles much more complicated systems +\item Sophisticated instruction set available +\item Allows for diagnostics and easy to troubleshoot +\end{itemize} + +\subsection{Component description} + +Programmable controllers have grown throughout industrial control +applications because of the ease they bring to creating a controller: +ease of programming, ease of wiring, ease of installation, and ease +of changing. PLCs span a wide range of sizes, but all contain six +basic components +\begin{itemize} +\item Processor or central processing unit (CPU) +\item Rack or Mounting +\item Input assembly +\item Output assembly +\item Power supply +\item Programming unit, device or PC +\end{itemize} + +\subsubsection{Rack Assembly} + +Most medium to large PLC systems are assembled such that the individual +components - CPU, Input/Output, Power Supply - are modules that are +held together within a rack. In smaller PLC systems - all of these +components may be contained in a single housing or \textquotedbl{}Brick\textquotedbl{} +- these smaller systems are sometimes referred to as \textquotedbl{}bricks\textquotedbl{} +or \textquotedbl{}shoebox\textquotedbl{} PLCs. + + +\subsubsection{Power Supply} + +The power supply provides power for the PLC system. The power supply +provides internal DC current to operate the processor logic circuitry +and input/output assemblies. Common power levels used are 24V DC or +120 VAC. + + +\subsubsection{Processor (CPU)} + +The processor, central processing unit, or CPU is the \textquotedbl{}brain\textquotedbl{} +of the PLC. The size and type of CPU will determine things like: the +programming functions available, size of the application logic available, +amount of memory available, and processing speed. Understanding the +CPU can be a complex subject and we will tackle that in other articles. + + +\subsubsection{Programming Device} + +The PLC is programmed using a specialty programmer or software on +a computer that can load and change the logic inside. Most modern +PLCs are programmed using software on a PC or laptop computer. Older +systems used a custom programming device. + + +\subsubsection{Input/Output Assembly} + +Many types of inputs and outputs can be connected to a PLC, and they +can all be divided into two large groups - analog and digital. Digital +inputs and outputs are those that operate due to a discrete or binary +change - on/off, yes/no. Analog inputs and outputs change continuously +over a variable range - pressure, temperature, potentiometer. + +\includegraphics[scale=0.8]{pasted1} + + +\paragraph{Configurations} + +PLCs are available in various configurations, which are chosen according +to the necessity of the work. Basic PLCs which are available on a +single PCB are called open-frame or single board PLCs; these are totally +self-sustained (except power supply) and can be directly mounted inside +the controls cabinet on threaded standoffs. They are inexpensive, +small, consume less power, easy to program but do not have large number +on inputs and outputs; their instruction set is also small. PLCs are +also available housed in a single case, with all inputs, outputs and +power supply points located in a single unit. This type is generally +chosen according to available program memory, required number and +voltage of inputs and outputs to suit the application. These systems +also have an expansion port which allows addition of specialized units. +More sophisticated units with wider array of options are modularized +PLCs. + + +\paragraph{Operation of a PLC} + +A PLC retains its operating system, user programs, and some data in +retentive (nonvolatile) memory. It executes an initialization step +when placed in run mode, and then repeatedly executes a scan cycle +sequence. The total time for one complete program scan is a function +of processor speed, I/O modules used, and length of user program (Ladder +Logic). + +The basic PLC scan cycle consists of three steps: +\begin{itemize} +\item An input scan: Data is taken from all input modules in the system +and placed into an area of PLC memory referred to as the input image +area +\item A user program scan: Data in the input image area is applied to the +user program, the user program is executed and the output image area +is updated +\item An output scan: data is taken from the output image area and sent +to all output modules in the system. +\end{itemize} +For the Allen-Bradley PLCs and the simulator used, the input and output +image areas (in addition and counters. Programs are written as Ladder +Logic for PLCs. It is written in rungs, which are individual structures +consisting of basic elements like NC/NO contacts, timers, counters, +etc. + + +\subsection{Basic Elements and Instructions} + + +\paragraph{Contacts} + +There are 2 types of contacts, normally open (NC) and normally open +(NO). When an NC contact is energized it opens and vice-versa. XIO +is used for an NC contact and XIO for an NO contact. + + +\paragraph{Outputs/Coil} + +The output for a rung is denoted by the instruction OTE. It is energized +when all the logics preceding it are true (1). The output can also +be latched and unlatched by OTL \& OTU respectively. + + +\paragraph{Timers} + +The most commonly used process control device after coils and contacts +is the timer. A timer is simply a control block that takes an input +and changes an output based on time. A PLC timerâs time may be a programmable +variable time as well as a fixed time. Many kinds of timers like Non-Retentive, +Timer Delay Off, Retentive, etc. are available. For our project we +have used NRT timers which get reset as and when the input is off. + +\includegraphics[scale=0.8]{pasted3} + + +\section{Instrument and Control Loops in Upgrading Plant} + +\begin{figure} + + +\protect\caption{\protect\includegraphics[scale=0.1]{WP_20140710_001}} + + +\end{figure} + + + +\subsection{Feed System} + +Feed tank level TK-5 and TK-13 are provided with level indicating +alarms LIA-12053 and LIA-12055 with a range of 0-2900 litres. They +have a high and low level adjustable set points and give high and +low level alarms. They receive signal from differential pressure transmitters +LT-12071 and LT-12076 respectively. Pressure switches are provided +for alarms and associated interlock circuits. Low levels in feed tank +also trips feed pump P-1 and P-2. + +Feed pumps P-1 and P-2 are provided with hand switches HS-12317 and +HS-12318 respectively. These hand switches have ON, AUTO-1, AUTO-2 +and OFF positions. AUTO-1 is connected to TK-5 low level alarm circuit +and AUTO-2 is connected to TK-13 low level alarm circuit. Depending +on the on line feed tank, HS of both feed pumps should be put in corresponding +AUTO position so that they trip when level in the tank goes down to +the trip level. + + +\subsubsection{Feed Flow Control Loop} + +Flow control loop measures, controls and records pre-set D2O feed +flow to the feed evaporator EV-1 from feed overflow tank TK-6. The +flow element FE-12147 and pneumatic recording controller FRC-12002 +have a range of 0-110 litres/hour(i.e. 0-1.833 lpm). The setting of +the flow has to be done manually depending on the feed concentration. + + +\subsubsection{Level of TK-6 Feed Overflow Tank} + +Low level alarm LA-10257 provided in TK-6 will caution failure of +feed pump. There will be sufficient hold up still to continue feed +for approximately one hour. Very low level alarm LA-12058 shuts off +the feed flow control valve CV-53. + + +\subsubsection{Feed Evaporator (EV-1) Level Control Loop} + +This controls steam flow into the evaporator EV-1. The control loop +has LOC-12005 with a range of 0-420 Litres (non-linear scale) and +receives signal from differential pressure transmitter LT-12072 and +gives signal to CV-272. + +The control loop maintains constant level in EV-1, so that controlled +feed flow from the flow control loop is completely evaporated and +fed into the column. + + +\subsection{Differential Pressure Control Loop for the Column} + +The performance of the distillation tower is very much dependent on +the pressure drop across the tower and on the boil up rate from the +reboiler. A variation in the boil up rate can vary the pressure drop +across the column. Hence, a control on $\triangle P$ which is cascaded +with the steam pressure control in reboiler is used to control simultaneously +$\triangle P$ across column and boil up from reboiler. The $\triangle P$ +control from FRC-12001 has a range of 0 to 300mm of Hg. (abs) (linear +scale) and can be set at required $\triangle P$ manually. $\triangle P$ +across the column is the primary variable. This receives signal from +$\triangle P$ transmitter DPT-12004 and gives signals to PIC-12008, +which is the pressure indicating controller for the steam line to +reboiler 150-S-1416. Signal from DPT-12044 adjusts the set point of +PIC-12008. PIC-12008 gets signal from absolute pressure transmitter +PT-12046 which senses and transmits steam pressure for line 150-S-146 +and gives signal to CV-266. Reboiler steam pressure is expected to +go below atmospheric pressure at times during operation and hence +an absolute pressure transmitter is used PT-12046. + +Also alarms for high pressure DPA-12004 drop across column and low +pressure drop DPA-12003 across column are provided on $\triangle P$ +control loop. Low will bring the column under total reflux. + + +\subsection{Vacuum Control Loop} + +The absolute pressure in the system is measured at the buffer tank +TK-1 by an absolute pressure transmitter PT-12045 and controlled by +a recording control on panel PRC-12005. This has a range of 0-200mm +of Hg. abs pressure. Control valve CV-159 is provided between TK-1 +and vacuum pump assembly. + +A bleed air facility with a 2 way solenoid valve SV-12322 is provided +at the inlet line of buffer tank (line 50-G-93). This is for enabling +the vacuum control valve CV-159 to function within its control range, +if the air leak to the process system is very small. Presetting the +bleed air is done by a fine needle valve. SV-12322 opens or shuts +off instrument air bleed into the system. + +Pressure switched for high pressure alarm is provided. PA-12021 very +high pressure in vacuum system will close CV-272, CV-73, CV-134, CV-266 +and shut down the plant. + + +\subsection{Water Circulating Tank (TK-4) Level and Temperature} + +Seal Water required for vacuum pump is taken from this tank(TK-4). +An ON-OFF type level control is provided to control level in this +tank. Level switches LA-12055(HIGH) and LA-12056(LOW) are also provided. +High level gives an alarm and cuts off make up water to the tank by +closing SV-202. Low Level will give an alarm and trip level will cut +off bleed air to vacuum system; close CV-159 and puts off water circulating +pumps P-16/P-17 and vacuum pumps P-7/P-8. LC-12007 level control provided +keeps steady level in TK-4 by supplying make up water through SV-202. + + +\subsection{Product and Reject Withdrawal System Column Sump (TK-7) Level Control} + +This is controlled either by product take off or reject take off depending +on the feed concentration. The high-low change over hand switch HS-12327 +connects this loop either to product CV-73 or reject CV-134 control +valve. This change over is at around a feed concentration of 60\% +or as per operational needs. + +Of the product and reject withdrawal, the lesser flow is controlled +by a timer loop and the larger flow of the two through the sump level +control loop. Flow limiter orifices FE-12150 (product) and FE-12151 +(reject) are provided on both the take-off lines with flow limit at +100kg/hr. + +Sump (TK-7) has differential pressure transmitters LT-12073 which +transmits signal to LIC-12073. Range if this is 0 to 1260 litres (non +linear scale) and has low (LA-12053) and high (LA-12054) alarms, which +are adjustable. + +The high level alarm will cut off steam supply to feed evaporator +and low level stops product and reject withdrawal. + + +\subsection{Reboiler Circulation} + +FE-12184 senses the flow. Flow indicating alarm FIA-12017 has adjustable +high and low positions and has a range of 0 to 333.3 lpm. It receives +signal from FT-12122. + +Low flow of circulation will give an alarm through a time delay relay +and will stop the recirculation pump and put the column under total +reflux. In this condition, standby pump will not start automatically. +Auto start of standby pump works only on over load tripping of running +pump. + + +\subsection{Steam System} + +Pressure control PIC-12008 controls steam pressure in EV-2 and in +cascade with $\triangle P$ control . Steam flow in reboiler EV-2 +is monitored by FT-12123 and FT-12105 which have a range of 0 to 4000 +kg/hr. Orifice FE-12149 senses the steam flow. + + +\subsection{Steam Condensate Tank Level} + +LA-12062 and LA-12061 with high and low level switches respectively +are provided on TK-12 which respectively starts and stops the pump +P-13/P-14 and pumps condensate back to boiler house/reactor source. + +Since both pumps are given hand switches with ON,AUTO,OFF positions, +both pumps will start at the tank high level and stop at tank low +level, if hand switches are placed in AUTO. Hence at a time only one +pump need to be placed on AUTO and the other may be placed on 'OFF'. + + +\subsection{Instrument Air} + +Instrument air supply pressure is expected at 10 kg/cm2. This is being +reduced by differential PRV's to 0.35 kg/cm2 for vacuum system bleed +air and 1.4 kg/cm2 for instruments. Pressure switch PS-12089 gives +low pressure alarm of the instrument air supply system. + + +\subsection{Product and Reject Tank Levels} + +These tanks are provided with visual level gauges and have low and +high level alarms. Low level alarms trip the product and reject pump. +\begin{itemize} +\item LIA-12056 and LT-12074 for product tank +\item LIA-12054 and LT-12075 for reject tank +\end{itemize} +Both have range of 0-1516 litres with adjustable high and low positons. + + +\subsection{Temperature Measurement and Alarms} + +Total six point R.T.D type temperature recorder (range 0-100oC) are +provided for temperature recording. The temperature points are as +follows +\begin{itemize} +\item Feed evaporator vapour outlet TR-12067 +\item Column sump TR-12065 +\item Column top TR-12066 +\item Reflux condenser cooling water out TR-12069 +\item Vent condenser exit TR-12068 +\end{itemize} +Three temperature alarms having a range of 0-60oC are provided at +the following points +\begin{itemize} +\item Water circulating tank TA-12033: gives alarm only +\item Vent Condenser exit TA-12031: will shut down the plant closing feed, +product and reject, and steam to EV-1 control valves +\item Product vent condenser exit TA-12032 will bring the column under total +reflux closing feed, product and reject control valves +\end{itemize} + +\chapter{Results and Discussion} + +The Programming of PLC is done by Ladder Logic for which we used Logix +Pro Software. Various steps followed for drawing a ladder diagram +\begin{enumerate} +\item Find the inputs and outputs +\item Familiarising with control logics +\item Making a Flow diagram of the process +\end{enumerate} +There of 32 inputs and outputs available in a I/O simulator in Logix +Pro which we used for simulation. + +\includegraphics{pasted4} + + +\section{Flow Diagrams} + +\includegraphics[scale=0.8]{FEED_PUMP_FLOW_CHART} + +\includegraphics[scale=0.3]{maps_feed_flow_diag} + + +\section{Ladder Logic} + + +\section{Explanation of Ladder Logic Diagram} + + +\chapter{Conclusion} + +The Project entitled âImplementation of PLC based system in Upgrading +Plantâ was pursued to complete the objective of learning about the +present relay system in MAPS and replacing it with PLC. From our work +under the guidance of our mentor we concluded the following things +\begin{itemize} +\item The hardwired electromagnetic based relays should be replaced with +PLC (Programmable Logic Controller) because of their advantages over +relays in flexibility and they are easy to maintain +\item Upgrading plant being one of the most oldest parts of MAPS, it needs +to be upgraded quickly to be able to use it smoothly for many years +to come. There may be some difficulties for upgradation but there +are many benefits to ripe in the future +\end{itemize} + +\chapter{Future Work} + + +\section{Implementing Microprocessor based System} + + +\subsection{Microprocessor} + +A microprocessor incorporates the functions of a computer's central +processing unit (CPU) on a single integrated circuit (IC), or at most +a few integrated circuits. All modern CPUs are microprocessors making +the micro- prefix redundant. The microprocessor is a multipurpose, +programmable device that accepts digital data as input, processes +it according to instructions stored in its memory, and provides results +as output. It is an example of sequential digital logic, as it has +internal memory. Microprocessors operate on numbers and symbols represented +in the binary numeral system. + +The integration of a whole CPU onto a single chip or on a few chips +greatly reduced the cost of processing power. The integrated circuit +processor was produced in large numbers by highly automated processes, +so unit cost was low. Single-chip processors increase reliability +as there are many fewer electrical connections to fail. As microprocessor +designs get faster, the cost of manufacturing a chip (with smaller +components built on a semiconductor chip the same size) generally +stays the same. + +Before microprocessors, small computers had been implemented using +racks of circuit boards with many medium- and small-scale integrated +circuits. Microprocessors integrated this into one or a few large-scale +ICs. Continued increases in microprocessor capacity have since rendered +other forms of computers almost completely obsolete (see history of +computing hardware), with one or more microprocessors used in everything +from the smallest embedded systems and handheld devices to the largest +mainframes and supercomputers. + + +\subsection{Using Microprocessor for Alarm Circuits} + +To start with we have used an 8086 Microprocessor and simulated the +Tank Level Alarm system which displays the level of water if everything +is normal and raises an alarm if the level exceeds the threshold level. +Threshold level has been directly set via the code. Keypad interface +can be added to set the threshold level. + +\includegraphics[scale=0.3]{Screenshot_from_2014-07-10_22:21:32} + + +\end{document} commit 4ad173670372218bf7800cf518a54fdb89d620a5 Author: Prannoy Pilligundla <prannoy.b...@gmail.com> Date: Tue Aug 5 00:15:01 2014 +0530 Added a general LyX test file Run "mk4ht ooxelatex PS_Report_Final.tex imageconfig.cfg" for the conversion. All the images in the lyx file have not been committed. One of each type i.e one normal image and an another in a float has been added. diff --git a/tests/PS_Report_Final.lyx b/tests/PS_Report_Final.lyx new file mode 100644 index 0000000..56a1ba0 --- /dev/null +++ b/tests/PS_Report_Final.lyx @@ -0,0 +1,2384 @@ +#LyX 2.1 created this file. For more info see http://www.lyx.org/ +\lyxformat 474 +\begin_document +\begin_header +\textclass report +\use_default_options true +\maintain_unincluded_children false +\language english +\language_package default +\inputencoding auto +\fontencoding global +\font_roman default +\font_sans default +\font_typewriter default +\font_math auto +\font_default_family default +\use_non_tex_fonts false +\font_sc false +\font_osf false +\font_sf_scale 100 +\font_tt_scale 100 +\graphics default +\default_output_format default +\output_sync 0 +\bibtex_command default +\index_command default +\paperfontsize default +\spacing single +\use_hyperref false +\papersize default +\use_geometry false +\use_package amsmath 1 +\use_package amssymb 1 +\use_package cancel 1 +\use_package esint 1 +\use_package mathdots 1 +\use_package mathtools 1 +\use_package mhchem 1 +\use_package stackrel 1 +\use_package stmaryrd 1 +\use_package undertilde 1 +\cite_engine basic +\cite_engine_type default +\biblio_style plain +\use_bibtopic false +\use_indices false +\paperorientation portrait +\suppress_date false +\justification true +\use_refstyle 1 +\index Index +\shortcut idx +\color #008000 +\end_index +\secnumdepth 3 +\tocdepth 3 +\paragraph_separation indent +\paragraph_indentation default +\quotes_language english +\papercolumns 1 +\papersides 1 +\paperpagestyle default +\tracking_changes false +\output_changes false +\html_math_output 0 +\html_css_as_file 0 +\html_be_strict false +\end_header + +\begin_body + +\begin_layout Title +Implementing PLC based system in Upgrading Plant +\end_layout + +\begin_layout Author +Prannoy Pilligundla 2012A8PS264P +\begin_inset Newline newline +\end_inset + +Siddarth Singh 2012AAPS823P +\begin_inset Newline newline +\end_inset + +Vineet Cherian 2012A3PS015P +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +tableofcontents +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Abstract +Heavy water which is used a moderator in a PHWR is often contaminated with + some chemical impurities and Light water. + The chemical impurities like corrosion products, oil, dirt etc are removed + from the downgraded Heavy water in the cleanup system before sending it + to Upgrading plant for further processing. + Basis of seperation of Heavy water and Light water is the difference in + Boiling point of 1.41 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C. + Upgrading is done by the continuous distillation under sub-atmospheric + condition. + The downgraded heavy water is boiled in a reboiler and made to ascend through + the packed distillation column. + It is condensed at the top in the reflux condensor and the condensed liquid + is putback at the top of the tower as reflux. + The vapour ascending and liquid descending will come in intimate contact + in tower section. + Due to this mass transfer takes place. + Ligher component H +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O is transferred to the vapour phase from liquid phase. + The mass transfer taking place in the tower sets up a concentration gradient + throughout the tower section. + Thus at the bottom of the tower it will be pure heavy water and at the + top of the column it will be light water. + The process instrumentation logic is based on the philosophy of simple + and safe operation. + Interlocks have been provided with process parameters to trip the plant + whenever unsafe conditions are developed. +\end_layout + +\begin_layout Abstract +Our main objective here is to upgrade an existing relay based control system + with a Programmable Logic Controller(PLC) in this Heavy Water Upgradation + Plant +\end_layout + +\begin_layout Standard +Heavy water which is used a moderator in a PHWR is often contaminated with + some chemical impurities and Light water. + The chemical impurities like corrosion products, oil, dirt etc are removed + from the downgraded Heavy water in the cleanup system before sending it + to Upgrading plant for further processing. + Basis of seperation of Heavy water and Light water is the difference in + Boiling point of 1.41 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C. + Upgrading is done by the continuous distillation under sub-atmospheric + condition. + The downgraded heavy water is boiled in a reboiler and made to ascend through + the packed distillation column. + It is condensed at the top in the reflux condensor and the condensed liquid + is putback at the top of the tower as reflux. + The vapour ascending and liquid descending will come in intimate contact + in tower section. + Due to this mass transfer takes place. + Ligher component H +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O is transferred to the vapour phase from liquid phase. + The mass transfer taking place in the tower sets up a concentration gradient + throughout the tower section. + Thus at the bottom of the tower it will be pure heavy water and at the + top of the column it will be light water. + The process instrumentation logic is based on the philosophy of simple + and safe operation. + Interlocks have been provided with process parameters to trip the plant + whenever unsafe conditions are developed. +\end_layout + +\begin_layout Chapter +Upgrading Plant +\end_layout + +\begin_layout Section +Introduction +\end_layout + +\begin_layout Standard +The Madras Atomic Power Station is designed of the CANDU type,almost similar + to the Rajasthan Atomic Power Station. + The Nuclear reactor is of natural Uranium, Heavy water moderated and cooled. + This Heavy Water gets depleted due to leakages in the system. + These leakages are mainly collected from fuelling machine vault, Primary + heat transfer system and boiler room. + In the +\begin_inset Quotes eld +\end_inset + +PHWR +\begin_inset Quotes erd +\end_inset + + type of reactors heavy water is used both as moderator and as heat transport + fluid. + Downgrading of high quality water occurs through two mechanisms: +\end_layout + +\begin_layout Enumerate +Light water leakage into the heavy water system. +\end_layout + +\begin_layout Enumerate +Heavy water escape from PHT and Moderator systems where it comes in contact + with light water +\end_layout + +\begin_layout Standard +Downgraded D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O is a mixture of light water, D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O and other solid and chemical impurities. + The downgraded heavy water containing various chemical impurities render + the heavy water unfit for use without further processing. + The chemical impurities like corrosion products, oil, dirt etc are removed + from the downgraded heavy water in the clean up system before sending it + to the upgrading plant for further processing. + The chemical purity should be strictly followed before processing the downgrade +d heavy water in the distillation plant. + +\end_layout + +\begin_layout Standard + +\emph on +Design Capacity of Distillation Columns +\emph default +: The distillation plant has been designed to process 36 litres/hr of 60%(w/w) + and 36 litres/hr of 30%(w/w) for bottom product at 99.8% D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O(w/w) with top reject of 0.5% D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O(w/w). + Based on the above performance data at 7800 operating hours oer year the + annual plant capacity is expected to be 250 tonnes of reactor grade Heavy + Water. +\end_layout + +\begin_layout Section +Distillation Processs +\end_layout + +\begin_layout Subsection +Principle of Operation +\end_layout + +\begin_layout Standard +Heavy Water(D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O) and Light Water(H +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O) are alike in their chemical properties but differ in their physical propertie +s. + At atmospheric pressure the boiling point of H +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O is 100 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C and boiling point of D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O is 101.42 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C. + Thus relative volatility ( Boiling point difference i.e 1.42 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C) is basis for seperation of D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O and H +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O in the distillation column. +\end_layout + +\begin_layout Standard +Upgrading is done by continuous distillation under sub atmospheric condition. + The downgraded heavy water is boiled in a reboiler and made to ascend through + the packed distillation column. + It is condensed at top in the reflux condenser and the condensed liquid + is put back at the top of the tower as reflux. + The vapour ascending and liquid descending will come in intimate contact + in the tower section. + Due to this mass transfer takes place. + Lighter component(H +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O) is transferred to the vapour phase from liquid phase. + The mass tranfer taking place in the tower sets up a concentration gradient + throughout the tower section. + Thus at the bottom of the tower,it will be pure heavy water and at the + top of column it will be light water. +\end_layout + +\begin_layout Standard +Part of the reboiler vapour is taken as product and part of the condensed + liquid from the reflux condenser is collected as reject (IP â¤0.25%w/w). + Depending on the feed concentration, feed is put into the tower at some + point along the height of the tower where the feed concentration matches + with the local concentration of the tower. +\end_layout + +\begin_layout Subsection +Process +\end_layout + +\begin_layout Standard +The principle of the distillation and equilibrium condition are mentioned + above. + It takes nearly three days i.e 72 hours to achieve this equilibrium condition. + Feed in the form of vapour will be added at a point in the column where + its Isotopic Purity (I.P) matches with the column section I.P. + Reject is removed from the top as a liquid and product is taken from the + bottom. + One important thing to be noticed is, the equilibrium should not be disturbed + at any condition. + This is possible if the feed rate is equal to the reject rate plus product + rate. + This is given below as the material balance equation. +\end_layout + +\begin_layout Standard +\begin_inset Formula +\begin{equation} +F=P+R +\end{equation} + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset Formula +\[ +F=\mathrm{Feed}\: Rate\: in\: lit/hr +\] + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset Formula +\[ +P=Product\: Rate\; in\: lit/hr +\] + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset Formula +\[ +R=Reject\: rate\: in\: lit/hr +\] + +\end_inset + + +\end_layout + +\begin_layout Standard +Mole fraction or Component(D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O) balance is given by +\end_layout + +\begin_layout Standard +\begin_inset Formula +\begin{equation} +FX_{F}=PX_{P}+RX_{R} +\end{equation} + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset Formula +\[ +X_{F}=D_{2}O\: fraction\: of\: feed +\] + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset Formula +\[ +X_{P}=D_{2}O\: fraction\: of\: feed +\] + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset Formula +\[ +X_{R}=D_{2}O\: fraction\: of\: Reject +\] + +\end_inset + + +\end_layout + +\begin_layout Standard +As per design, for a specified feed I.P the feed rate should not exceed above + a certain value. + This is given in the table and also in the graph. + Product and Reject I.P's are as oer our requirements i.e reject I.P<0.25% and + Product I.P>99.97% for moderator grade and >99.4% for PHT grade liquid. + Hence X +\begin_inset script subscript + +\begin_layout Plain Layout +F +\end_layout + +\end_inset + +,X +\begin_inset script subscript + +\begin_layout Plain Layout +P +\end_layout + +\end_inset + +,X +\begin_inset script subscript + +\begin_layout Plain Layout +R +\end_layout + +\end_inset + + and F are fixed. + To find out the product and reject rates the above two equations can be + solved to get +\end_layout + +\begin_layout Standard +\begin_inset Formula +\begin{equation} +P=\frac{F(X_{F}-X_{R})}{(X_{P}-X_{R})} +\end{equation} + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset Formula +\begin{equation} +R=F-P +\end{equation} + +\end_inset + + +\end_layout + +\begin_layout Standard +For a distillation column the seperation factor achieved is 1.05. + Seperation factor is defined as follows: +\end_layout + +\begin_layout Standard +\begin_inset Formula +\[ +Seperation\: Factor=\frac{\frac{atom\: fraction\: of\: H_{2}}{atom\: fraction\: of\: D_{2}}\: in\: gas}{\quad\frac{atom\: fraction\: of\: H_{2}}{atom\: fraction\: of\: D_{2}}\: in\: liquid} +\] + +\end_inset + + +\end_layout + +\begin_layout Standard +The maximum attainable seperation factor is 1.05 as per design. + To achieve this the column pressure should be reduced. + This pressure cannot be reduced beyond a certain value because of the increase + in the specific volume of vapour which inturn leads to very high column + dimensions and inturn increases the column cost. + Since the process water temperature is limited around 33 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C, there is always a lower limit on the temperature of the vapour which + is required to be cooled, so that efficient condensation can take place. + (This inturn means a low pressure restriction inside the column top, which + is 120mm of Hg absolute). + Column sump pressure is around 230mm of Hg.abs. +\end_layout + +\begin_layout Subsection +Definitions +\end_layout + +\begin_layout Paragraph +Total Reflux +\end_layout + +\begin_layout Standard +Total Reflux implies that there is no feed, no product, and reject take + off i.e 3493 CV-53, 3493 CV-272, 3493 CV-73 and 3493 CV-134 are closed. +\end_layout + +\begin_layout Paragraph +Shut down of the distillation column +\end_layout + +\begin_layout Standard +In addition to the total reflux state, the reboiler steam control CV-266 + is also closed in this state. +\end_layout + +\begin_layout Subsection +Specification of feed D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O +\end_layout + +\begin_layout Enumerate +K ⤠5 micromho/cm or microsiemens/cm +\end_layout + +\begin_layout Enumerate +PH 6.5 to 8 +\end_layout + +\begin_layout Enumerate +Chloride ⤠0.5ppm +\end_layout + +\begin_layout Enumerate +Nitrate ⤠1ppm +\end_layout + +\begin_layout Enumerate +Oil Free +\end_layout + +\begin_layout Enumerate +Particulate matter free +\end_layout + +\begin_layout Enumerate +Organic materials ⤠10ppm ammonia and amines +\end_layout + +\begin_layout Section +Equipment Description +\end_layout + +\begin_layout Subsection +Distillation Column +\end_layout + +\begin_layout Standard +Distillation column consists of 14 identical sections with sump at the bottom. + At the top of the column reflux condenser CD-4 and a vent condenser CD-5 + are present to condense the vapours. + Operating temperature and pressure varies from 74 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C and 230mm Hg(abs)-at column sump to 56 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C and 120mm Hg(abs) at the top. + Outside diameter and height of each column section is â2.5mm and 3200â3mm + respectively. + Each column section is packed with corrugated phosphor bronze wire mesh + packing with a coating of copper oxide for surface activation which increases + wet surface. + This packing is supported by means of a bottom ring. + The top support ring supports the liquid distributor, which distributes + the liquid evenly on the packing. + Liquid collector collects the downcoming liquid and puts it onto the distributi +on without hindering the vapour flow. + For the fourteenth section liquid collector is not required +\end_layout + +\begin_layout Subsection +Column Sump +\end_layout + +\begin_layout Standard +Column sump at the bottom of the column holds the downcoming reflux liquid + from the distillation column and provides flooded suction to the reboiler + circulating pump. + Capacity of the sump is decided on the initial hold up required for flooding + the distillation column. + This requirement is around 3 tonnes. +\end_layout + +\begin_layout Subsection +Reboiler EV-2 +\end_layout + +\begin_layout Standard +A falling film type reboiler is provided for reboiling the reflux liquid + of the distillation tower. + It is a shell and tube type 1-1Hx. + Liquid is pumped to the top of the tubesheet of the reboiler and falls + thorugh the tubes in the form of a film and is vapourised. + The vapour along with the liquid comes down from the bottom side and enters + the column sump. + For getting a good heat transfer coefficient a 4.5:1 circulation ratio is + to be used. +\end_layout + +\begin_layout Standard +Special features of falling film reboiler are: +\end_layout + +\begin_layout Itemize +High heat tranfer coefficient due to the turbulent film flowin tubes. +\end_layout + +\begin_layout Itemize +Low hold up because tubes are not completely filled. +\end_layout + +\begin_layout Subsection +Reflux Condenser(CD-4) +\end_layout + +\begin_layout Standard +This is a 2-2 shell and tube Hx, cooled by process water, used to condense + the ascending vapours and to provide reflux to distillation column. + In the vapour hood portion an annular space serves as the reflux drum, + where condensate gets collected and overflows into the distillation column. + This reduces the reflux holdup considerably. + The temperature of the column at the reflux end is 55.3 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C. +\end_layout + +\begin_layout Subsection +Feed Evaporator(EV-1) +\end_layout + +\begin_layout Standard +It is a jacketed vessel with a surface area of 1.2Sq.m. + Feed heavy water is boiled in this vessel and is fed to the column in the + vapour form. + Steam condenses in the jacket and goes to steam condensate collection tank + TK-15. +\end_layout + +\begin_layout Subsection +Product Condenser(CD-2) +\end_layout + +\begin_layout Standard +This is a 1:2 shell and tube type of Hx with a surface are of 5.5M +\begin_inset script superscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + + used to condensate the vapour form the collection sump which goes down + to the product tank TK-10. +\end_layout + +\begin_layout Subsection +Vent Condenser(CD-5) +\end_layout + +\begin_layout Standard +This is a 1:2 shell and tube condenser with a surface are of 3.6M +\begin_inset script superscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +which condenses any vapour that escapes uncondensed from the reflux condenser. + Chilled water is used as the cooling media in this condenser. +\end_layout + +\begin_layout Subsection +Exhaust Cooler(CD-1) +\end_layout + +\begin_layout Standard +It is a 1:2 shell and tube type condenser used to trap any vapour escaping + from vacuum pump exhaust, feed tank and feed overflow tank vent line. +\end_layout + +\begin_layout Subsection +Product vent condenser CD-6 and Product tank vent cold trap CD-3 +\end_layout + +\begin_layout Standard +Both are of similar geometry and construction. + CD-6 condenses the escaping vapours from product condenser whereas CD-3 + acts as a trap for product tank TK-10 +\end_layout + +\begin_layout Subsection +Water circulating tank TK-4 vacuum pump and cyclone seperators(TK-2 & TK-3) +\end_layout + +\begin_layout Standard +To create and maintain vacuum at the distillation column two 100% capacity + vacuum pumps are used. + To provide cooling two 100% capacity vacuum pumps are used. + To provide cooling water for these pumps at the rate of 14lpm in a closed + loop circulation arrangement, a water circulating tank and two 100% capacity + pumps are provided. + A chilled water cooling arrangement is provided for cooling the seal liquid + TK-4. + A cyclone separator is provided at the exhaust of each vacuum pump to separate + the seal water from the exhaust vapours going to exhaust cooler thereby + reducing the load on the exhaust cooler, +\begin_inset script subscript + +\begin_layout Plain Layout +1 +\end_layout + +\end_inset + +H +\begin_inset script superscript + +\begin_layout Plain Layout +3 +\end_layout + +\end_inset + +affinity towards water is more and so it gets diluted with water and +\begin_inset script subscript + +\begin_layout Plain Layout +1 +\end_layout + +\end_inset + +H +\begin_inset script superscript + +\begin_layout Plain Layout +3 +\end_layout + +\end_inset + + free air which further cooled in CD-1 is sent out to atmosphere. +\end_layout + +\begin_layout Subsection +Feed tank TK-5 & TK-13 +\end_layout + +\begin_layout Standard +This tank stores the depleted D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O from the evaporation clean up section. + Capacity of these tanks are 3170 litres eac. + This is based on holding 48 hours feed at a time for the distillation tower. + The second tank is used to prepare feed stock when the first one is in + stream. +\end_layout + +\begin_layout Subsection +Product storage tank TK-10 +\end_layout + +\begin_layout Standard +Reactor grade D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O is collected in this tank from the distillation process. + This is intermittently pump to drums and sent to station whenever required. +\end_layout + +\begin_layout Subsection +Reject storage tank TK-10 +\end_layout + +\begin_layout Standard +Reject containing ⤠0.25% I.P liquid is collected in this tank and then it + is sent out to liquid effluent management plant(LEMP). +\end_layout + +\begin_layout Subsection +Feed Overflow tank TK-6 +\end_layout + +\begin_layout Standard +This tank provides feed flow to the feed evaporator at constant head which + can be further controlled by a flow control loop arrangement controlling + CV-53. +\end_layout + +\begin_layout Subsection +Buffer tank TK-1 +\end_layout + +\begin_layout Standard +This tank acts as a buffer in the vacuum system. +\end_layout + +\begin_layout Subsection +Steam Condensate tank TK-15 +\end_layout + +\begin_layout Standard +This tank collects the steam condensate from evaporator EV-1 & EV-2 and + puts back the condensates to deaerator for steam generation in the boilers + with the help of steam condensate pumps 4321-P-16 & P-17. +\end_layout + +\begin_layout Subsection +Product & Reject overflow vessels TK-8 & TK-9 +\end_layout + +\begin_layout Standard +These two graduated vessels have the following functions +\end_layout + +\begin_layout Enumerate +To keep sufficient holdup of liquid to provide barometer head +\end_layout + +\begin_layout Enumerate +To calibrate the product and reject flow through orifices. + They are provided with integral visual level gauges. +\end_layout + +\begin_layout Subsection +Pumps +\end_layout + +\begin_layout Standard +All pumps are used in the upgrading plant for +\family roman +\series medium +\shape up +\size normal +\emph off +\bar no +\strikeout off +\uuline off +\uwave off +\noun off +\color none +D +\begin_inset script subscript + +\begin_layout Plain Layout + +\family roman +\series medium +\shape up +\size normal +\emph off +\bar no +\strikeout off +\uuline off +\uwave off +\noun off +\color none +2 +\end_layout + +\end_inset + +O service are canned motor pumps to attain zero leakage. +\end_layout + +\begin_layout Subsection +Reboiler circulating pumps +\end_layout + +\begin_layout Standard +These pumps provide circulation for falling film type reboiler EV-2. + Only one pump is operated at a time. + The other pump will be standby. +\end_layout + +\begin_layout Subsection +Feed, Product and Reject transfer pumps +\end_layout + +\begin_layout Standard +These are +\begin_inset Formula $2\times100\%$ +\end_inset + + capacity. + These are required for pumping liquid from feed tanks to feed overflow + tank TK-6. + Product transfer pump is used to transfer the reactor grade D +\begin_inset script subscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +O from product tank TK-10 to drums and reject transfer pump is used to pump + the water in reject tank TK-11 to LEMP. +\end_layout + +\begin_layout Subsection +Cooling water pumps 7131-P9, P10, P-11 +\end_layout + +\begin_layout Standard +These are +\begin_inset Formula $2\times100\%$ +\end_inset + + capacity pumps used for boosting the pressure of the cooling water to 9Kg/cm +\begin_inset script superscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + + which is required at the reflux condenser as per design. + During plant startup both the pumps can be run. +\end_layout + +\begin_layout Subsection +Chilled water booster pumps 7192-P-5, P-6 & P-7 +\end_layout + +\begin_layout Standard +These are 100% capacity pumps. + These pumps boost the chilled water pressure required for the vent condenser + and cold traps. +\end_layout + +\begin_layout Section +Inter connection with other system +\end_layout + +\begin_layout Subsection +Steam Requirement +\end_layout + +\begin_layout Standard +Approximately 5000Kg/hr of dry saturated steam at a pressure of 1.8Kg/cm +\begin_inset script superscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +is required during the startup of distillation for flooding operation. + After some 3 to 4 hours during normal operation the requirement is 3400Kg/hr + at a pressure of 1.8Kg/cm +\begin_inset script superscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +. +\end_layout + +\begin_layout Subsection +Cooling Water Requirement +\end_layout + +\begin_layout Standard +Cooling water requirement of 250M +\begin_inset script superscript + +\begin_layout Plain Layout +3 +\end_layout + +\end_inset + +/hr at 9Kg/cm +\begin_inset script superscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +and 33 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C is required during normal operation for reflux condenser and product condenser + of both the distillation columns. + During flooding 400M +\begin_inset script superscript + +\begin_layout Plain Layout +3 +\end_layout + +\end_inset + +/hr of process water will be required for both the distillation columns. +\end_layout + +\begin_layout Subsection +Chilled Water +\end_layout + +\begin_layout Standard +Chilled water is required for vent condensers, vacuum pump assembly and + also for vent cold traps. + 15M +\begin_inset script superscript + +\begin_layout Plain Layout +3 +\end_layout + +\end_inset + +/hr of chilled water at 9Kg/cm +\begin_inset script superscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +is required for the above chilled water loads. +\end_layout + +\begin_layout Subsection +Electrical Power +\end_layout + +\begin_layout Standard +Power supply required for this plant is 400/400 volts, 3à HZ A.C 180 KW. + Installed capacity is 400KW. +\end_layout + +\begin_layout Subsection +Instrument Air +\end_layout + +\begin_layout Standard +Oil free, moisture free air at a pressure of 5.3Kg/cm +\begin_inset script superscript + +\begin_layout Plain Layout +2 +\end_layout + +\end_inset + +is required for pneumatic instruments. +\end_layout + +\begin_layout Section +Interlocks & Logics +\end_layout + +\begin_layout Subsection +Safety Interlocks +\end_layout + +\begin_layout Standard +There are two conditions which can shutdown the plant. + They are +\end_layout + +\begin_layout Itemize +High temperature in vacuum line +\begin_inset Formula $50-G-93$ +\end_inset + + in CD-5 exit +\end_layout + +\begin_layout Itemize +Failure of vacuum which results in very high pressure alarm of vacuum line + +\begin_inset Formula $50-G-93$ +\end_inset + + +\end_layout + +\begin_layout Standard +The following are the interlocks provided for pytting the column under total + reflux +\end_layout + +\begin_layout Itemize +Low +\begin_inset Formula $\triangle P$ +\end_inset + + +\end_layout + +\begin_layout Itemize +Low flow in reboiler EV-2 i.e < 7M +\begin_inset script superscript + +\begin_layout Plain Layout +3 +\end_layout + +\end_inset + +/hr +\end_layout + +\begin_layout Itemize +High temperature in CD-6(product vent condenser) i.e >25 +\begin_inset script superscript + +\begin_layout Plain Layout +o +\end_layout + +\end_inset + +C +\end_layout + +\begin_layout Standard +Hand switches, Indicators, Controllers for most of the equipments covered + in distillation process are in upgrading plant control room located in + first floor of upgrading plant. +\end_layout + +\begin_layout Subsection +Feed Pump Hand Switch +\end_layout + +\begin_layout Standard +Feed pump starts if there is no overload and emergency push button is not + pressed and HS is in ON position or HS is in auto 1 position and low level + in TK-5 is not existing or HS is in auto 2 position and low level in TK-13 + is not existing. + Running feed pump stops if overload exists or emergency push button is + pressed or HS is kept in auto 2 position and low level exists in TK-13 +\end_layout + +\begin_layout Subsection +Feed Flow Control +\end_layout + +\begin_layout Standard +Feed flow from feed overflow tank to feed evaporator is measured by FE-12147 + and this signal is fed through a FRC-12202 to control CV-53 (Presently + in MAPS, the feed flow is set and controlled by a rotameter) +\end_layout + +\begin_layout Subsection +Feed Overflow tank level +\end_layout + +\begin_layout Standard +Low level in this TK-6 will close CV-53. + Alarm +\begin_inset Quotes eld +\end_inset + +low level in TK-6 +\begin_inset Quotes erd +\end_inset + + also comes in UGP control room. + This TK-6 inventory is sufficient to continue the operation of the distillation + column for approximately 1 hour with the inflow to TK-6 is stopped +\end_layout + +\begin_layout Subsection +Feed Evaporator (EV-1) level control loop +\end_layout + +\begin_layout Standard +LT-12072 measures the EV-1 level and controls steam CV-272 through a controller + LIC-12005 so that the evaporator level is maintained. + This implies that whatever is the inflow to EV-1 from TK-6 will be evaporated + and fed to distillation column. +\end_layout + +\begin_layout Subsection +Differential pressure control loop for the column +\end_layout + +\begin_layout Standard +The performance of the distillation tower is very much dependent on the + pressure drop across the tower and on the boil up rate from reboiler. + A variation in boil up rate can vary the pressure drop across the column. + Hence, control on +\begin_inset Formula $\triangle P$ +\end_inset + + which is cascaded with the steam pressure control in reboiler is used to + control +\begin_inset Formula $\triangle P$ +\end_inset + + across the column and boilup from reboiler. + A larms are provided for high and low +\begin_inset Formula $\triangle P$ +\end_inset + + in the column. + A low +\begin_inset Formula $\triangle P$ +\end_inset + + will put the column under total reflux. +\end_layout + +\begin_layout Subsection +Vacuum Control Loop +\end_layout + +\begin_layout Standard +PT-12045 senses the pressure at the buffer tank and controls CV-159 such + that 120mm of Hg absolute is maintained at the top of the column. + A bleed air facility with a 2 way solenoid valve is provided so that CV-159 + will operate well in its control range, if the air leak to the process + system is very small. + Presetting of the bleed air is done by a needle valve, which is in series + with the solenoid valve +\end_layout + +\begin_layout Subsection +Water circulating tank TK-4 level control +\end_layout + +\begin_layout Standard +High level in TK-4 closes SV-12325 and stops DM water addition and also + it gives an alarm. + Low level in TK-4 annunciates and also it closes CV-159, stops bleed air + flow, stop vacuum pumps and seal water circulating pumps. + LC-12007 level control provided keeps steady level in TK-4 by supply make + up water through SV-12325 +\end_layout + +\begin_layout Subsection +Product and Reject withdrawal system +\end_layout + +\begin_layout Subsubsection +Column sump (TK-7) level control +\end_layout + +\begin_layout Standard +This controls product (reject) flow through CV-73 (CV-134), if the feed + IP >50% and HS-12327 is in High (Low) position. + The lesser of these two flow (Product & Reject flows) is controlled by + timer and the larger of these two flows is controlled by column sump level + control +\end_layout + +\begin_layout Standard +Flow restriction orifices in the product and reject lines which limit the + flow to 100Kg/hr +\end_layout + +\begin_layout Standard +Low sump level will stop product and reject withdrawal. + High sump level will cut off steam supply to feed evaporator +\end_layout + +\begin_layout Subsubsection +Timer Circuit Control +\end_layout + +\begin_layout Standard +The lower of the two product and reject withdrawal rate is controlled by + a timer circuit. + If feed IP is less(more) than HS-12327 will be low(high) and timer will + control CV-73(CV-134). + First timer gets energized and opens the CV-73 (CV-134) for a certain period + as determined in the setting. + When the first timer is timed out the second timer is energized and this + closes the CV-73 (CV-134). + This continues in a cyclic manner and hence maintains the rate of withdrawal + of product (Reject) +\end_layout + +\begin_layout Subsection +Reboiler Circulation +\end_layout + +\begin_layout Standard +High heat transfer is achieved if there is a turbulent to the film flow + in the tubes. + If low flow is existing then running reboiler pump trips and the plant + will run under total reflux. + Auto starting of standby pump works only on over-load tripping of running + pump if reboiler circulation is less than 7M +\begin_inset script superscript + +\begin_layout Plain Layout +3 +\end_layout + +\end_inset + +/hr. + Then CV-266 will be closed to safeguard EV-2 +\end_layout + +\begin_layout Subsection +Steam Condensate tank TK-15 level control +\end_layout + +\begin_layout Standard +Steam condensate pumps (2x100% capacity) can be started/stopped manually. + In auto condition, these pumps start if tank level is high and stop when + TK-12 level is low. +\end_layout + +\begin_layout Subsection +Instrument Air Pressure +\end_layout + +\begin_layout Standard +Air supply pressure is 10Kg/sq.cm. + If it is 100psi then air pressure low alarm comes in UGP control room. +\end_layout + +\begin_layout Subsection +Product and Reject Tank Level Control +\end_layout + +\begin_layout Standard +Low level in these tanks trips the corresponding pumps low and high level + alarms are provided in upgrading plant control room +\end_layout + +\begin_layout Chapter +Experimental Details and Concepts Involved +\end_layout + +\begin_layout Section +Programmable Logic Controller (PLC) +\end_layout + +\begin_layout Subsection +Introduction +\end_layout + +\begin_layout Standard +A PLC (Programmable Logic Controller) is defined as a user-friendly, microproces +sor based specialized computer that carries out control functions of many + types and levels of complexity. + The first PLC systems evolved from conventional computers in the late 1960s + and early 1970s. + These first PLCs were installed primarily in automotive plants. + What has taken months back then takes few days today. + Many companies like Allen-Bradley, Mitsubishi, and Siemens manufacture + PLCs. + In conventional controllers the functions are determined by their physical + wiring, whereas the functions of PLCs are defined by a program. + They are also connected to other parts with cable , but the content of + their program memory can be changed at any time to adapt their programs + to different control tasks. +\end_layout + +\begin_layout Subsection +Advantages of using PLC +\end_layout + +\begin_layout Itemize +Flexible +\end_layout + +\begin_layout Itemize +Faster response time +\end_layout + +\begin_layout Itemize +Simpler Wiring +\end_layout + +\begin_layout Itemize +Modular Design- easy to repair and expand +\end_layout + +\begin_layout Itemize +Handles much more complicated systems +\end_layout + +\begin_layout Itemize +Sophisticated instruction set available +\end_layout + +\begin_layout Itemize +Allows for diagnostics and easy to troubleshoot +\end_layout + +\begin_layout Subsection +Component description +\end_layout + +\begin_layout Standard +Programmable controllers have grown throughout industrial control applications + because of the ease they bring to creating a controller: ease of programming, + ease of wiring, ease of installation, and ease of changing. + PLCs span a wide range of sizes, but all contain six basic components +\end_layout + +\begin_layout Itemize +Processor or central processing unit (CPU) +\end_layout + +\begin_layout Itemize +Rack or Mounting +\end_layout + +\begin_layout Itemize +Input assembly +\end_layout + +\begin_layout Itemize +Output assembly +\end_layout + +\begin_layout Itemize +Power supply +\end_layout + +\begin_layout Itemize +Programming unit, device or PC +\end_layout + +\begin_layout Subsubsection +Rack Assembly +\end_layout + +\begin_layout Standard +Most medium to large PLC systems are assembled such that the individual + components - CPU, Input/Output, Power Supply - are modules that are held + together within a rack. + In smaller PLC systems - all of these components may be contained in a + single housing or "Brick" - these smaller systems are sometimes referred + to as "bricks" or "shoebox" PLCs. +\end_layout + +\begin_layout Subsubsection +Power Supply +\end_layout + +\begin_layout Standard +The power supply provides power for the PLC system. + The power supply provides internal DC current to operate the processor + logic circuitry and input/output assemblies. + Common power levels used are 24V DC or 120 VAC. +\end_layout + +\begin_layout Subsubsection +Processor (CPU) +\end_layout + +\begin_layout Standard +The processor, central processing unit, or CPU is the "brain" of the PLC. + The size and type of CPU will determine things like: the programming functions + available, size of the application logic available, amount of memory available, + and processing speed. + Understanding the CPU can be a complex subject and we will tackle that + in other articles. +\end_layout + +\begin_layout Subsubsection +Programming Device +\end_layout + +\begin_layout Standard +The PLC is programmed using a specialty programmer or software on a computer + that can load and change the logic inside. + Most modern PLCs are programmed using software on a PC or laptop computer. + Older systems used a custom programming device. +\end_layout + +\begin_layout Subsubsection +Input/Output Assembly +\end_layout + +\begin_layout Standard +Many types of inputs and outputs can be connected to a PLC, and they can + all be divided into two large groups - analog and digital. + Digital inputs and outputs are those that operate due to a discrete or + binary change - on/off, yes/no. + Analog inputs and outputs change continuously over a variable range - pressure, + temperature, potentiometer. +\end_layout + +\begin_layout Standard +\begin_inset Graphics + filename pasted1.png + scale 80 + +\end_inset + + +\end_layout + +\begin_layout Paragraph +Configurations +\end_layout + +\begin_layout Standard +PLCs are available in various configurations, which are chosen according + to the necessity of the work. + Basic PLCs which are available on a single PCB are called open-frame or + single board PLCs; these are totally self-sustained (except power supply) + and can be directly mounted inside the controls cabinet on threaded standoffs. + They are inexpensive, small, consume less power, easy to program but do + not have large number on inputs and outputs; their instruction set is also + small. + PLCs are also available housed in a single case, with all inputs, outputs + and power supply points located in a single unit. + This type is generally chosen according to available program memory, required + number and voltage of inputs and outputs to suit the application. + These systems also have an expansion port which allows addition of specialized + units. + More sophisticated units with wider array of options are modularized PLCs. +\end_layout + +\begin_layout Paragraph +Operation of a PLC +\end_layout + +\begin_layout Standard +A PLC retains its operating system, user programs, and some data in retentive + (nonvolatile) memory. + It executes an initialization step when placed in run mode, and then repeatedly + executes a scan cycle sequence. + The total time for one complete program scan is a function of processor + speed, I/O modules used, and length of user program (Ladder Logic). +\end_layout + +\begin_layout Standard +The basic PLC scan cycle consists of three steps: +\end_layout + +\begin_layout Itemize +An input scan: Data is taken from all input modules in the system and placed + into an area of PLC memory referred to as the input image area +\end_layout + +\begin_layout Itemize +A user program scan: Data in the input image area is applied to the user + program, the user program is executed and the output image area is updated +\end_layout + +\begin_layout Itemize +An output scan: data is taken from the output image area and sent to all + output modules in the system. +\end_layout + +\begin_layout Standard +For the Allen-Bradley PLCs and the simulator used, the input and output + image areas (in addition and counters. + Programs are written as Ladder Logic for PLCs. + It is written in rungs, which are individual structures consisting of basic + elements like NC/NO contacts, timers, counters, etc. +\end_layout + +\begin_layout Subsection +Basic Elements and Instructions +\end_layout + +\begin_layout Paragraph +Contacts +\end_layout + +\begin_layout Standard +There are 2 types of contacts, normally open (NC) and normally open (NO). + When an NC contact is energized it opens and vice-versa. + XIO is used for an NC contact and XIO for an NO contact. +\end_layout + +\begin_layout Paragraph +Outputs/Coil +\end_layout + +\begin_layout Standard +The output for a rung is denoted by the instruction OTE. + It is energized when all the logics preceding it are true (1). + The output can also be latched and unlatched by OTL & OTU respectively. +\end_layout + +\begin_layout Paragraph +Timers +\end_layout + +\begin_layout Standard +The most commonly used process control device after coils and contacts is + the timer. + A timer is simply a control block that takes an input and changes an output + based on time. + A PLC timerâs time may be a programmable variable time as well as a fixed + time. + Many kinds of timers like Non-Retentive, Timer Delay Off, Retentive, etc. + are available. + For our project we have used NRT timers which get reset as and when the + input is off. +\end_layout + +\begin_layout Standard +\begin_inset Graphics + filename pasted3.png + lyxscale 50 + scale 80 + +\end_inset + + +\end_layout + +\begin_layout Section +Instrument and Control Loops in Upgrading Plant +\end_layout + +\begin_layout Standard +\begin_inset Float figure +wide false +sideways false +status open + +\begin_layout Plain Layout + +\end_layout + +\begin_layout Plain Layout +\begin_inset Caption Standard + +\begin_layout Plain Layout +\begin_inset Graphics + filename WP_20140710_001.jpg + lyxscale 20 + scale 10 + +\end_inset + + +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Plain Layout + +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Subsection +Feed System +\end_layout + +\begin_layout Standard +Feed tank level TK-5 and TK-13 are provided with level indicating alarms + LIA-12053 and LIA-12055 with a range of 0-2900 litres. + They have a high and low level adjustable set points and give high and + low level alarms. + They receive signal from differential pressure transmitters LT-12071 and + LT-12076 respectively. + Pressure switches are provided for alarms and associated interlock circuits. + Low levels in feed tank also trips feed pump P-1 and P-2. +\end_layout + +\begin_layout Standard +Feed pumps P-1 and P-2 are provided with hand switches HS-12317 and HS-12318 + respectively. + These hand switches have ON, AUTO-1, AUTO-2 and OFF positions. + AUTO-1 is connected to TK-5 low level alarm circuit and AUTO-2 is connected + to TK-13 low level alarm circuit. + Depending on the on line feed tank, HS of both feed pumps should be put + in corresponding AUTO position so that they trip when level in the tank + goes down to the trip level. +\end_layout + +\begin_layout Subsubsection +Feed Flow Control Loop +\end_layout + +\begin_layout Standard +Flow control loop measures, controls and records pre-set D2O feed flow to + the feed evaporator EV-1 from feed overflow tank TK-6. + The flow element FE-12147 and pneumatic recording controller FRC-12002 + have a range of 0-110 litres/hour(i.e. + 0-1.833 lpm). + The setting of the flow has to be done manually depending on the feed concentra +tion. +\end_layout + +\begin_layout Subsubsection +Level of TK-6 Feed Overflow Tank +\end_layout + +\begin_layout Standard +Low level alarm LA-10257 provided in TK-6 will caution failure of feed pump. + There will be sufficient hold up still to continue feed for approximately + one hour. + Very low level alarm LA-12058 shuts off the feed flow control valve CV-53. +\end_layout + +\begin_layout Subsubsection +Feed Evaporator (EV-1) Level Control Loop +\end_layout + +\begin_layout Standard +This controls steam flow into the evaporator EV-1. + The control loop has LOC-12005 with a range of 0-420 Litres (non-linear + scale) and receives signal from differential pressure transmitter LT-12072 + and gives signal to CV-272. +\end_layout + +\begin_layout Standard +The control loop maintains constant level in EV-1, so that controlled feed + flow from the flow control loop is completely evaporated and fed into the + column. +\end_layout + +\begin_layout Subsection +Differential Pressure Control Loop for the Column +\end_layout + +\begin_layout Standard +The performance of the distillation tower is very much dependent on the + pressure drop across the tower and on the boil up rate from the reboiler. + A variation in the boil up rate can vary the pressure drop across the column. + Hence, a control on +\begin_inset Formula $\triangle P$ +\end_inset + + which is cascaded with the steam pressure control in reboiler is used to + control simultaneously +\begin_inset Formula $\triangle P$ +\end_inset + + across column and boil up from reboiler. + The +\begin_inset Formula $\triangle P$ +\end_inset + + control from FRC-12001 has a range of 0 to 300mm of Hg. + (abs) (linear scale) and can be set at required +\begin_inset Formula $\triangle P$ +\end_inset + + manually. + +\begin_inset Formula $\triangle P$ +\end_inset + + across the column is the primary variable. + This receives signal from +\begin_inset Formula $\triangle P$ +\end_inset + + transmitter DPT-12004 and gives signals to PIC-12008, which is the pressure + indicating controller for the steam line to reboiler 150-S-1416. + Signal from DPT-12044 adjusts the set point of PIC-12008. + PIC-12008 gets signal from absolute pressure transmitter PT-12046 which + senses and transmits steam pressure for line 150-S-146 and gives signal + to CV-266. + Reboiler steam pressure is expected to go below atmospheric pressure at + times during operation and hence an absolute pressure transmitter is used + PT-12046. +\end_layout + +\begin_layout Standard +Also alarms for high pressure DPA-12004 drop across column and low pressure + drop DPA-12003 across column are provided on +\begin_inset Formula $\triangle P$ +\end_inset + + control loop. + Low will bring the column under total reflux. +\end_layout + +\begin_layout Subsection +Vacuum Control Loop +\end_layout + +\begin_layout Standard +The absolute pressure in the system is measured at the buffer tank TK-1 + by an absolute pressure transmitter PT-12045 and controlled by a recording + control on panel PRC-12005. + This has a range of 0-200mm of Hg. + abs pressure. + Control valve CV-159 is provided between TK-1 and vacuum pump assembly. +\end_layout + +\begin_layout Standard +A bleed air facility with a 2 way solenoid valve SV-12322 is provided at + the inlet line of buffer tank (line 50-G-93). + This is for enabling the vacuum control valve CV-159 to function within + its control range, if the air leak to the process system is very small. + Presetting the bleed air is done by a fine needle valve. + SV-12322 opens or shuts off instrument air bleed into the system. +\end_layout + +\begin_layout Standard +Pressure switched for high pressure alarm is provided. + PA-12021 very high pressure in vacuum system will close CV-272, CV-73, + CV-134, CV-266 and shut down the plant. +\end_layout + +\begin_layout Subsection +Water Circulating Tank (TK-4) Level and Temperature +\end_layout + +\begin_layout Standard +Seal Water required for vacuum pump is taken from this tank(TK-4). + An ON-OFF type level control is provided to control level in this tank. + Level switches LA-12055(HIGH) and LA-12056(LOW) are also provided. + High level gives an alarm and cuts off make up water to the tank by closing + SV-202. + Low Level will give an alarm and trip level will cut off bleed air to vacuum + system; close CV-159 and puts off water circulating pumps P-16/P-17 and + vacuum pumps P-7/P-8. + LC-12007 level control provided keeps steady level in TK-4 by supplying + make up water through SV-202. +\end_layout + +\begin_layout Subsection +Product and Reject Withdrawal System Column Sump (TK-7) Level Control +\end_layout + +\begin_layout Standard +This is controlled either by product take off or reject take off depending + on the feed concentration. + The high-low change over hand switch HS-12327 connects this loop either + to product CV-73 or reject CV-134 control valve. + This change over is at around a feed concentration of 60% or as per operational + needs. +\end_layout + +\begin_layout Standard +Of the product and reject withdrawal, the lesser flow is controlled by a + timer loop and the larger flow of the two through the sump level control + loop. + Flow limiter orifices FE-12150 (product) and FE-12151 (reject) are provided + on both the take-off lines with flow limit at 100kg/hr. +\end_layout + +\begin_layout Standard +Sump (TK-7) has differential pressure transmitters LT-12073 which transmits + signal to LIC-12073. + Range if this is 0 to 1260 litres (non linear scale) and has low (LA-12053) + and high (LA-12054) alarms, which are adjustable. +\end_layout + +\begin_layout Standard +The high level alarm will cut off steam supply to feed evaporator and low + level stops product and reject withdrawal. +\end_layout + +\begin_layout Subsection +Reboiler Circulation +\end_layout + +\begin_layout Standard +FE-12184 senses the flow. + Flow indicating alarm FIA-12017 has adjustable high and low positions and + has a range of 0 to 333.3 lpm. + It receives signal from FT-12122. +\end_layout + +\begin_layout Standard +Low flow of circulation will give an alarm through a time delay relay and + will stop the recirculation pump and put the column under total reflux. + In this condition, standby pump will not start automatically. + Auto start of standby pump works only on over load tripping of running + pump. +\end_layout + +\begin_layout Subsection +Steam System +\end_layout + +\begin_layout Standard +Pressure control PIC-12008 controls steam pressure in EV-2 and in cascade + with +\begin_inset Formula $\triangle P$ +\end_inset + + control . + Steam flow in reboiler EV-2 is monitored by FT-12123 and FT-12105 which + have a range of 0 to 4000 kg/hr. + Orifice FE-12149 senses the steam flow. +\end_layout + +\begin_layout Subsection +Steam Condensate Tank Level +\end_layout + +\begin_layout Standard +LA-12062 and LA-12061 with high and low level switches respectively are + provided on TK-12 which respectively starts and stops the pump P-13/P-14 + and pumps condensate back to boiler house/reactor source. +\end_layout + +\begin_layout Standard +Since both pumps are given hand switches with ON,AUTO,OFF positions, both + pumps will start at the tank high level and stop at tank low level, if + hand switches are placed in AUTO. + Hence at a time only one pump need to be placed on AUTO and the other may + be placed on 'OFF'. +\end_layout + +\begin_layout Subsection +Instrument Air +\end_layout + +\begin_layout Standard +Instrument air supply pressure is expected at 10 kg/cm2. + This is being reduced by differential PRV's to 0.35 kg/cm2 for vacuum system + bleed air and 1.4 kg/cm2 for instruments. + Pressure switch PS-12089 gives low pressure alarm of the instrument air + supply system. +\end_layout + +\begin_layout Subsection +Product and Reject Tank Levels +\end_layout + +\begin_layout Standard +These tanks are provided with visual level gauges and have low and high + level alarms. + Low level alarms trip the product and reject pump. +\end_layout + +\begin_layout Itemize +LIA-12056 and LT-12074 for product tank +\end_layout + +\begin_layout Itemize +LIA-12054 and LT-12075 for reject tank +\end_layout + +\begin_layout Standard +Both have range of 0-1516 litres with adjustable high and low positons. +\end_layout + +\begin_layout Subsection +Temperature Measurement and Alarms +\end_layout + +\begin_layout Standard +Total six point R.T.D type temperature recorder (range 0-100oC) are provided + for temperature recording. + The temperature points are as follows +\end_layout + +\begin_layout Itemize +Feed evaporator vapour outlet TR-12067 +\end_layout + +\begin_layout Itemize +Column sump TR-12065 +\end_layout + +\begin_layout Itemize +Column top TR-12066 +\end_layout + +\begin_layout Itemize +Reflux condenser cooling water out TR-12069 +\end_layout + +\begin_layout Itemize +Vent condenser exit TR-12068 +\end_layout + +\begin_layout Standard +Three temperature alarms having a range of 0-60oC are provided at the following + points +\end_layout + +\begin_layout Itemize +Water circulating tank TA-12033: gives alarm only +\end_layout + +\begin_layout Itemize +Vent Condenser exit TA-12031: will shut down the plant closing feed, product + and reject, and steam to EV-1 control valves +\end_layout + +\begin_layout Itemize +Product vent condenser exit TA-12032 will bring the column under total reflux + closing feed, product and reject control valves +\end_layout + +\begin_layout Chapter +Results and Discussion +\end_layout + +\begin_layout Standard +The Programming of PLC is done by Ladder Logic for which we used Logix Pro + Software. + Various steps followed for drawing a ladder diagram +\end_layout + +\begin_layout Enumerate +Find the inputs and outputs +\end_layout + +\begin_layout Enumerate +Familiarising with control logics +\end_layout + +\begin_layout Enumerate +Making a Flow diagram of the process +\end_layout + +\begin_layout Standard +There of 32 inputs and outputs available in a I/O simulator in Logix Pro + which we used for simulation. +\end_layout + +\begin_layout Standard +\begin_inset Graphics + filename pasted4.png + lyxscale 80 + +\end_inset + + +\end_layout + +\begin_layout Section +Flow Diagrams +\end_layout + +\begin_layout Standard +\begin_inset Graphics + filename FEED_PUMP_FLOW_CHART.jpg + lyxscale 60 + scale 80 + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset Graphics + filename maps_feed_flow_diag.jpg + lyxscale 30 + scale 30 + +\end_inset + + +\end_layout + +\begin_layout Section +Ladder Logic +\end_layout + +\begin_layout Section +Explanation of Ladder Logic Diagram +\end_layout + +\begin_layout Chapter +Conclusion +\end_layout + +\begin_layout Standard +The Project entitled âImplementation of PLC based system in Upgrading Plantâ + was pursued to complete the objective of learning about the present relay + system in MAPS and replacing it with PLC. + From our work under the guidance of our mentor we concluded the following + things +\end_layout + +\begin_layout Itemize +The hardwired electromagnetic based relays should be replaced with PLC (Programm +able Logic Controller) because of their advantages over relays in flexibility + and they are easy to maintain +\end_layout + +\begin_layout Itemize +Upgrading plant being one of the most oldest parts of MAPS, it needs to + be upgraded quickly to be able to use it smoothly for many years to come. + There may be some difficulties for upgradation but there are many benefits + to ripe in the future +\end_layout + +\begin_layout Chapter +Future Work +\end_layout + +\begin_layout Section +Implementing Microprocessor based System +\end_layout + +\begin_layout Subsection +Microprocessor +\end_layout + +\begin_layout Standard +A microprocessor incorporates the functions of a computer's central processing + unit (CPU) on a single integrated circuit (IC), or at most a few integrated + circuits. + All modern CPUs are microprocessors making the micro- prefix redundant. + The microprocessor is a multipurpose, programmable device that accepts + digital data as input, processes it according to instructions stored in + its memory, and provides results as output. + It is an example of sequential digital logic, as it has internal memory. + Microprocessors operate on numbers and symbols represented in the binary + numeral system. +\end_layout + +\begin_layout Standard +The integration of a whole CPU onto a single chip or on a few chips greatly + reduced the cost of processing power. + The integrated circuit processor was produced in large numbers by highly + automated processes, so unit cost was low. + Single-chip processors increase reliability as there are many fewer electrical + connections to fail. + As microprocessor designs get faster, the cost of manufacturing a chip + (with smaller components built on a semiconductor chip the same size) generally + stays the same. +\end_layout + +\begin_layout Standard +Before microprocessors, small computers had been implemented using racks + of circuit boards with many medium- and small-scale integrated circuits. + Microprocessors integrated this into one or a few large-scale ICs. + Continued increases in microprocessor capacity have since rendered other + forms of computers almost completely obsolete (see history of computing + hardware), with one or more microprocessors used in everything from the + smallest embedded systems and handheld devices to the largest mainframes + and supercomputers. +\end_layout + +\begin_layout Subsection +Using Microprocessor for Alarm Circuits +\end_layout + +\begin_layout Standard +To start with we have used an 8086 Microprocessor and simulated the Tank + Level Alarm system which displays the level of water if everything is normal + and raises an alarm if the level exceeds the threshold level. + Threshold level has been directly set via the code. + Keypad interface can be added to set the threshold level. +\end_layout + +\begin_layout Standard +\begin_inset Graphics + filename Screenshot_from_2014-07-10_22:21:32.png + lyxscale 50 + scale 30 + +\end_inset + + +\end_layout + +\begin_layout Standard + +\end_layout + +\end_body +\end_document diff --git a/tests/PS_Report_Final.odt b/tests/PS_Report_Final.odt new file mode 100644 index 0000000..1113e48 Binary files /dev/null and b/tests/PS_Report_Final.odt differ diff --git a/tests/Screenshot_from_2014-07-10_22:21:32.png 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