[Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette
See Railway age gazette, Volume 53, No. 24, 1912, p. 1148. I kid you not. http://books.google.com/books?id=QrElMAAJpg=PA1148lpg=PA1148 This document says superheating is safe and effective for switching engines. I read somewhere else they tended to explode, so they stopped putting superheaters in them. Maybe that was before 1912. This says: Steam of such high degrees of superheat can be exposed to the cooling action of the steam chest and cylinder walls without condensation and at the same time has about 30 per cent, greater specific volume than saturated steam of the same pressure. A large part of this increased specific volume is again lost before expansion of the steam in the cylinders takes place on account of the cooling action of the steam chest and cylinder walls. While the superheat of the steam leaving the superheater may be 200 to 250 deg., the average superheat of the steam in the cylinder at the moment the cut-off takes place is hardly more than 100 deg.; but the entire elimination of all losses through condensation, together with the remaining increased volume of the steam, effects under average conditions a saving of 30 per cent, and more in the steam consumption per indicated horse power, which gain corresponds to a saving in fuel consumption of from 20 to 25 per cent., compared with a saturated steam locomotive working under the same conditions. . . . . . . The second requirement assumes that the increased volume of steam be expanded as efficiently, or in other words, that the same cut-offs be used as in the.saturated steam engine. This would mean a corresponding increase in cylinder dimensions which in many cases is not possible on account of limitations in adhesive weight, strength of running gear and other limitations There will always be an increase in hauling capacity obtainable, but whether the theoretical maximum can be obtained depends on the size of cylinders, and depends also on the quality of the saturated steam engines with which the superheater engine is compared, or to which the superheater has been applied, whether the engine is correctly proportioned or over cylindered, or deficient in boiler capacity, etc. It depends also on the service in which the locomotives are used; whether the service is such as to be favorable to developments of higher degrees of superheat and more or less unfavorable to the saturated steam locomotive. In switching service superheater engines make a very favorable showing, although only a moderate degree of superheat is being developed, but the improvement in efficiency is so remarkable because the saturated switch engine is the most inefficient locomotive type. Under all these varying service conditions the increased hauling capacity of superheater locomotives obtained in practical service varies between 20 and 30 per cent., and frequently even more. . . . Elsewhere it says that saturated steam caused a lot of wear and tear. I think the second dome at the top is the steam distributor, not the superheater. I hate to point to this but . . . see: http://en.wikipedia.org/wiki/Steam_locomotive_components Item 9. See also: http://en.wikipedia.org/wiki/Steam_locomotive QUOTE: Steam circuit The steam generated in the boiler fills the steam space above the water in the partially filled boiler. Its maximum working pressure is limited by spring-loaded safety valves. It is then collected either in a perforated tube fitted above the water level or from a dome that often houses the regulator valve, or throttle, the purpose of which is to control the amount of steam leaving the boiler. The steam then either travels directly along and down a steam pipe to the engine unit or may first pass into the wet header of a superheater, the role of the latter being to improve thermal efficiency and eliminate water droplets suspended in the saturated steam, the state in which it leaves the boiler. . . . END QUOTE - Jed
Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette
That is an interesting article isn't it? I guess those guys knew how to make good steam engines in the old days. I noticed that the superheated steam is at a temperature a bit higher than the direct steam generated in the boiler. The pressure must be established within the boiler so I guess the hotter steam does not make its way back to the boiler. Is it likely that some form of check valve is used at the throttle? If that were possible, then higher pressure could be applied to the cylinders due to the super heater. This might be dangerous to do, since then the boiler would be forced to increase pressure to overcome the check valve blockage. Maybe I just talked myself out of the check valve possibility. :-) (thinking Rossi's design) I hope these steam locomotives are not bombs looking for a chance to explode! Jed, I gather from the remainder of the article that a saturated steam locomotive is used in some applications. This suggests to me that the quality of the steam is pretty good. Does anyone else have engineering data concerning the expected value? Dave -Original Message- From: Jed Rothwell jedrothw...@gmail.com To: vortex-l vortex-l@eskimo.com Sent: Wed, Dec 7, 2011 5:02 pm Subject: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette See Railway age gazette, Volume 53, No. 24, 1912, p. 1148. I kid you not. http://books.google.com/books?id=QrElMAAJpg=PA1148lpg=PA1148 This document says superheating is safe and effective for switching engines. I read somewhere else they tended to explode, so they stopped putting superheaters in them. Maybe that was before 1912. This says: Steam of such high degrees of superheat can be exposed to the cooling action of the steam chest and cylinder walls without condensation and at the same time has about 30 per cent, greater specific volume than saturated steam of the same pressure. A large part of this increased specific volume is again lost before expansion of the steam in the cylinders takes place on account of the cooling action of the steam chest and cylinder walls. While the superheat of the steam leaving the superheater may be 200 to 250 deg., the average superheat of the steam in the cylinder at the moment the cut-off takes place is hardly more than 100 deg.; but the entire elimination of all losses through condensation, together with the remaining increased volume of the steam, effects under average conditions a saving of 30 per cent, and more in the steam consumption per indicated horse power, which gain corresponds to a saving in fuel consumption of from 20 to 25 per cent., compared with a saturated steam locomotive working under the same conditions. . . . . . . The second requirement assumes that the increased volume of steam be expanded as efficiently, or in other words, that the same cut-offs be used as in the.saturated steam engine. This would mean a corresponding increase in cylinder dimensions which in many cases is not possible on account of limitations in adhesive weight, strength of running gear and other limitations There will always be an increase in hauling capacity obtainable, but whether the theoretical maximum can be obtained depends on the size of cylinders, and depends also on the quality of the saturated steam engines with which the superheater engine is compared, or to which the superheater has been applied, whether the engine is correctly proportioned or over cylindered, or deficient in boiler capacity, etc. It depends also on the service in which the locomotives are used; whether the service is such as to be favorable to developments of higher degrees of superheat and more or less unfavorable to the saturated steam locomotive. In switching service superheater engines make a very favorable showing, although only a moderate degree of superheat is being developed, but the improvement in efficiency is so remarkable because the saturated switch engine is the most inefficient locomotive type. Under all these varying service conditions the increased hauling capacity of superheater locomotives obtained in practical service varies between 20 and 30 per cent., and frequently even more. . . . Elsewhere it says that saturated steam caused a lot of wear and tear. I think the second dome at the top is the steam distributor, not the superheater. I hate to point to this but . . . see: http://en.wikipedia.org/wiki/Steam_locomotive_components Item 9. See also: http://en.wikipedia.org/wiki/Steam_locomotive QUOTE: Steam circuit The steam generated in the boiler fills the steam space above the water in the partially filled boiler. Its maximum working pressure is limited by spring-loaded safety valves. It is then collected either in a perforated tube fitted above the water level or from a dome that often houses the regulator valve, or throttle, the purpose of which is to control the amount of steam leaving the boiler
Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette
On Wed, Dec 7, 2011 at 4:38 PM, David Roberson dlrober...@aol.com wrote: The pressure must be established within the boiler so I guess the hotter steam does not make its way back to the boiler. Is it likely that some form of check valve is used at the throttle? If that were possible, then higher pressure could be applied to the cylinders due to the super heater. It's not necessary to use higher pressure to superheat steam. In fact, the point is that the temperature of the steam is above the boiling point at the local pressure. Otherwise, it's saturated.
Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette
David Roberson dlrober...@aol.com wrote: I hope these steam locomotives are not bombs looking for a chance to explode! They often did explode, unfortunately, even in the 1930s, at the pinnacle of the technology. Maybe a single pipe explosion or an accident was more common than a boiler failure . . . I do not know. As I said, I read somewhere that superheater failures and explosions were common in some types of locomotives, so they stopped using them. I remember reading the memoir of a steam locomotive engineer who said they lived in fear of explosions, and saw a lot of people killed by them. Marine steam engines were terribly dangerous, according to my dad who was a fireman in the 1930s. These were oil fired, when you finally got the damn thing to light. Jed, I gather from the remainder of the article that a saturated steam locomotive is used in some applications. This suggests to me that the quality of the steam is pretty good. Yup. It was definitely used on the simpler, cheaper engines. That is what this and other sources say, including Wikipedia. - Jed
Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette
That is what I was saying, maybe in a convoluted way. The check valve was a technique that actually would allow higher temperature and pressure to exist outside of the main boiler region. -Original Message- From: Joshua Cude joshua.c...@gmail.com To: vortex-l vortex-l@eskimo.com Sent: Wed, Dec 7, 2011 6:12 pm Subject: Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette On Wed, Dec 7, 2011 at 4:38 PM, David Roberson dlrober...@aol.com wrote: The pressure must be established within the boiler so I guess the hotter steam does not make its way back to the boiler. Is it likely that some form of check valve is used at the throttle? If that were possible, then higher pressure could be applied to the cylinders due to the super heater. It's not necessary to use higher pressure to superheat steam. In fact, the point is that the temperature of the steam is above the boiling point at the local pressure. Otherwise, it's saturated.
Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette
I bet they did not allow children to ride in the locomotive with their fathers! I wonder why the superheating was so dangerous? I guess we might find out in the future if the main source of output power for LENR devices are steam engines. Dave -Original Message- From: Jed Rothwell jedrothw...@gmail.com To: vortex-l vortex-l@eskimo.com Sent: Wed, Dec 7, 2011 6:13 pm Subject: Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette David Roberson dlrober...@aol.com wrote: I hope these steam locomotives are not bombs looking for a chance to explode! They often did explode, unfortunately, even in the 1930s, at the pinnacle of the technology. Maybe a single pipe explosion or an accident was more common than a boiler failure . . . I do not know. As I said, I read somewhere that superheater failures and explosions were common in some types of locomotives, so they stopped using them. I remember reading the memoir of a steam locomotive engineer who said they lived in fear of explosions, and saw a lot of people killed by them. Marine steam engines were terribly dangerous, according to my dad who was a fireman in the 1930s. These were oil fired, when you finally got the damn thing to light. Jed, I gather from the remainder of the article that a saturated steam locomotive is used in some applications. This suggests to me that the quality of the steam is pretty good. Yup. It was definitely used on the simpler, cheaper engines. That is what this and other sources say, including Wikipedia. - Jed
Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette
Many modern power plants run at close to 1,000F and at 3,000 psi. The weight of steam equals the weigh of water under this super-critical condition. Water does not boil but gets thinner and thinner. Solids do not accumulate in the boiler and there is no boiler blow down. Any solids in the water get carried through and deposited on the turbine. Water treating is a science with these boilers. The re heaters glow red hot in the turbine room. Materials in the boiler tend to fail under this heat. More recently boilers have moved away from this condition and backed off on temperature a bit. They are not as efficient but more reliable and milder steel may be used in more of the construction. Frank Z
Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette
That pressure gives me visions of people being cut in to pieces by steam pressure. I recall an old friend saying that they once carried brooms within ships using high pressure steam. The broom was swept in front of you as you searched for small leaks. It was better to replace brooms than hands. Dave -Original Message- From: fznidarsic fznidar...@aol.com To: vortex-l vortex-l@eskimo.com Sent: Wed, Dec 7, 2011 6:36 pm Subject: Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette Many modern power plants run at close to 1,000F and at 3,000 psi. The weight of steam equals the weigh of water under this super-critical condition. Water does not boil but gets thinner and thinner. Solids do not accumulate in the boiler and there is no boiler blow down. Any solids in the water get carried through and deposited on the turbine. Water treating is a science with these boilers. The re heaters glow red hot in the turbine room. Materials in the boiler tend to fail under this heat. More recently boilers have moved away from this condition and backed off on temperature a bit. They are not as efficient but more reliable and milder steel may be used in more of the construction. Frank Z
Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette
On 11-12-07 06:11 PM, Joshua Cude wrote: On Wed, Dec 7, 2011 at 4:38 PM, David Roberson dlrober...@aol.com mailto:dlrober...@aol.com wrote: The pressure must be established within the boiler so I guess the hotter steam does not make its way back to the boiler. Is it likely that some form of check valve is used at the throttle? If that were possible, then higher pressure could be applied to the cylinders due to the super heater. It's not necessary to use higher pressure to superheat steam. In fact, the point is that the temperature of the steam is above the boiling point at the local pressure. Otherwise, it's saturated. The point in superheating in a locomotive wasn't to increase the pressure, it was to increase the *volume*. (In fact, the whole point in turning the water into steam to start with was simply to increase the volume. The *pressure* couldn't very well exceed the pressure of the water being delivered to the boiler from the tender, and that would have been determined by a pump. Exceed that pressure and your boiler will eventually run dry.) In fact, the non-super-heated and the superheated steam in the locomotive were at the s*ame pressure*. Actually, come to think of it, since the superheated steam was downstream from the cooler steam, and some amount of backpressure must result from forcing gas through pipes, the superheated steam must have been at a slightly *lower* pressure than the cooler steam. Somewhat similarly, when you drive a fuel-injected car, the fuel is injected into the cylinders at high pressure, and the point in burning it is to increase its *volume*. The pressure in the cylinder head isn't going to exceed the fuel pressure in the injectors! (Granted, the *air* is introduced at much lower pressure, and the pressure in the cylinder head goes up rapidly during the burn, but it's still not going to go high enough to force fuel back into the injectors. Note that this observation doesn't apply to carbureted cars, where _all_ fluids are introduced into the cylinder at low pressure.)
Re: [Vo]:Discussion of saturated steam locomotive versus superheated from Railroad Age Gazette
On Wed, Dec 7, 2011 at 7:36 PM, Stephen A. Lawrence sa...@pobox.com wrote: Somewhat similarly, when you drive a fuel-injected car, the fuel is injected into the cylinders at high pressure, and the point in burning it is to increase its volume. You know that it is only recently that gasoline automobiles had direct fuel injection. Diesel engines have used direct injection for ages and required almost 800 lbs of fuel pressure utilizing engine driven pumps. Gasoline engines in prior years used fuel injection into the intake manifold. They used electric pumps with only about 80 lbs of injector pressure. T
