Hi Tom,
Turboden et al claim that the lower temperatures and pressures in an ORC
system compared to an SRC system of similar size lead to reduced
maintenance costs and - as a guy with a specialist high-pressure steam
ticket is no longer required - also lower operations costs. I was
wondering what you have come across which leads you to say below:
"The manpower and capital requirements are pretty similar for both the steam and ORC
systems because of safety and other considerations."
What are the varied experiences with hot oil you mention? There have
been some spectacular fires at thermal oil plants - there's a cracker of
a YouTube video showing one from memory somewhere in the US NE - but the
industry says that the newer oils are much less flammable
Thanks
David
On 3/02/2013 7:00 AM, [email protected] wrote:
Message: 7
Date: Fri, 1 Feb 2013 15:43:08 -0800
From: "Tom Miles"<[email protected]>
To: "'Discussion of biomass pyrolysis and gasification'"
<[email protected]>
Subject: Re: [Gasification] Gasification Digest, Vol 30, Issue 1: ORC,
gasifier, SRC systems at around the 2MWe level
Message-ID:<[email protected]>
Content-Type: text/plain; charset="us-ascii"
David,
Heat rates were calculated the American way, using HHV.:-)
Steam and ORC was proposed in different configurations. A couple of
companies proposed using backpressure turbines or steam engines with oil
heated from the exhaust to drive an ORC turbine. Other proposed hot oil
boilers and ORC turbines. The 20% efficiency of Turboden and others is 20%
of the heat input to the turbine so you have to subtract the efficiency of
converting the wet wood fuel to hot oil which runs from 62-72% of HHV
depending on the MC of the fuel and the boiler configuration. Now since you
have 70% of the heat input exiting the ORD as waste heat you need to dump it
to a heat consumer. That work fine if you have an onsite heat consumer or
district heat arrangement. Unfortunately most of our American towns are not
laid out so conveniently that we can afford to build a district heat system
for a small biomass plant.
I agree that for all the literature on ORC there are very few head to head
comparisons with steam of CAPEX and OPEX. The manpower and capital
requirements are pretty similar for both the steam and ORC systems because
of safety and other considerations. In the end the levelized cost of
electricity (LCOE) will be higher for the ORC if you don't have a heat
customer. If your need is primarily heat , or if you have waste heat
available, the ORC systems look great. A new 2 MWe plant on Vancouver island
with a PW/Turboden ORC uses oil from an existing hot oil boiler at a wood
plant. There are many more hot oil systems in use in Canada than in the US.
We have had varied experience with hot oil here.
Tom
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