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Thread: 1903 six HP steam engine powers modern off grid power system

  1. #211
    I just became aware of a small scale steam engine system constructed and operated during the early 1980's. It was used to heat and power a modern home in Pennsylvania. It was fueled by anthracite coal. I understand there is an ASME paper describing the details. So, if I can get the paper, then I will post it here.

    The details I acquired show the system was extremely efficient. Well, actually, since it used saturated steam at only 135 psig and atmospheric exhaust, the highest possible efficiency is very low under these parameters. However, it showed 80%+ of Rankine cycle efficiency (or theoretical maximum). I would not have thought it possible to do so well in so small an engine (actually, until I get the ASME paper, then I am going to doubt the figure). The White Cliffs expander was measured at about 70% of Rankine cycle efficiency using saturated steam at 540 psig and exhausting to a condenser at 160F (roughly 3.5 psia). There were additional losses in that engine due to the incomplete expansion (since it used high pressure steam plus a condenser under vacuum), clearance volume losses due to the bump valve configuration, thermal losses mainly from the high temperature differential in the cylinder (but also the higher steam temperatures), and the higher pressure likely contributed to steam leakage past the rings. Also important is small steam engines are very poor at extracting work from low pressure steam. So, a small engine with atmospheric exhaust can potentially show a very high percentage of theoretical maximum efficiency provided the other losses are minimized.

    The expander was a single cylinder, single-acting, uniflow piston engine converted from a small industrial internal combustion engine. The steam admission used a single poppet valve with a push rod and cam. The system operated 24/7 during the heating seasons over a period of four years. Typical operating speed was 600 rpm. Power output was about 2 hp.

    http://www.thesteamboatingforum.net/...ile.php?id=187
    http://www.thesteamboatingforum.net/...ile.php?id=186
    Last edited by buenijo; 10-03-2019 at 04:06 PM.
    “The beginning of wisdom is to call things by their proper name.” - Confucius.
    "When plunder becomes a way of life for a group of men living together in society, they create for themselves in the course of time a legal system that authorizes it and a moral code that glorifies it." - Frederic Bastiat
    "Being well adjusted to a sick society is not a measure of health." - Jiddu Krishnamurti



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  3. #212
    Still doing a bit of casual reading on steam engine systems. The same engineer who devised the residential scale CHP steam engine system described in the previous post also devised and operated a small steam generator using a simple principle I considered years ago. Apparently, it works very well. A problem with traditional monotube steam generators is the water feed rate must be closely matched to the furnace output. Otherwise, insufficient water flow can lead to excessive temperatures and possible tube burnout (or lube oil destruction), or excess water flow can flood the coil and carry water into the engine. The solution here is simple: just pump excess water at all times, then use a small separator vessel to accept the steam/water mixture from the tube - pressurized saturated steam is taken from the top and saturated water is drained from the bottom. The water level remains more or less constant as long as the orifice to the drain line is properly selected with respect to size. Turns out the mass flow rate of water through an orifice is on the order of 10 times greater than steam. So, very little steam can escape. As long as what little steam escapes has its heat captured and regenerated into the system (along with saturated water that drains through), then there is no loss beyond the very slight mechanical energy needed to operate the pump at the higher rate. Well, this reminded me of another idea. As long as the peak temperature of the water/steam is limited, then oil can be circulated with the steam/water without separation. This has been done before. As I recall, the early Doble steam cars did this for a while. However, they did show some problems that I suspect were caused by excessive steam temperatures. Taking the temperature down a notch while using very good synthetic oil should solve the problem (I speculate). Maintaining a steam generator of the type described here would allow for never superheating the steam - so the oil would be positively protected from excessive temperatures. Yeah, efficiency would be capped, but dry saturated steam can show good results - especially at higher pressures. NOTE: However, the steam/water separator should do well to remove most of any lube oil. Therefore, the saturated steam taken off the top could be shunted through a superheater to increase efficiency.

    An interesting dynamic on heat transfer is counterintuitive to many. Consider the following: compare two steam generator tubes (one steel and one copper) that have the same dimensions. Now, with all else equal, which one will generate steam at the higher rate when heated by the same furnace? The answer is the rate will not differ by much. The higher thermal conductivity of copper is not a significant factor here because it's the low rate of heat transfer from the flue gases to the outer tubing wall that is the bottleneck. It turns out the temperature of the inside tube wall is on the order of only 10F higher than the steam/water flowing within. The outside tube wall temperature for the copper might be just 2-3 degrees F hotter than the inner wall temperature. The outside tube wall temperature for the steel will be higher than the copper, but only on the order of 20-30 degrees F (based on the thermal conductivity of copper being roughly 10 times higher than carbon steel). So, this lower outer tube temperature for copper makes negligible difference to heat transfer rates when the furnace temperature is 1500F. Now, if one were using a liquid heat transfer fluid to generate steam, or using much lower temperatures, then copper might make sense - but not when using a furnace directly. Anyway, considering this, then it seems reasonable to circulate oil with the water/steam provided the steam generator tubing is always flooded with some water thereby making superheating impossible. If the pressure is set at say 300 psig, then the temperature of the oil could never rise above the saturation temperature for water at this pressure (which is 421F). Many synthetic lube oils can handle this temperature. Yeah, the efficiency of the system would be limited, but I've shown that it's possible to achieve 10-12% overall thermal efficiency at this steam temperature - with a good design. If the heat from the system is the main energy requirement, then efficiency doesn't matter so much. However, again, optimizing efficiency is important because good design can increase the efficiency many fold over poor design - and while being simpler mechanically! For example, the steam engine system that started this thread is quite literally 2-3% efficient in converting the chemical energy in wood to shaft work. A safer, simpler, and much more compact system can increase efficiency four fold - and it can be practical in the sense that it need be fueled only once or twice daily while it runs unattended to provide heat and electricity. The most recently described steam system proves it's possible to do this - after all, it was constructed and operated over a period of four years to heat and power a modern home.
    Last edited by buenijo; 06-16-2019 at 11:08 AM.
    “The beginning of wisdom is to call things by their proper name.” - Confucius.
    "When plunder becomes a way of life for a group of men living together in society, they create for themselves in the course of time a legal system that authorizes it and a moral code that glorifies it." - Frederic Bastiat
    "Being well adjusted to a sick society is not a measure of health." - Jiddu Krishnamurti

  4. #213
    “The beginning of wisdom is to call things by their proper name.” - Confucius.
    "When plunder becomes a way of life for a group of men living together in society, they create for themselves in the course of time a legal system that authorizes it and a moral code that glorifies it." - Frederic Bastiat
    "Being well adjusted to a sick society is not a measure of health." - Jiddu Krishnamurti

  5. #214
    Quote Originally Posted by buenijo View Post
    I would like to buy one, or a build one. Doesn't appear that it's available in the US.

  6. #215
    Just found a lead on a 7 HP vertical single, like the one in the OP, in working condition for a decent price.

  7. #216
    Quote Originally Posted by Anti Federalist View Post
    Just found a lead on a 7 HP vertical single, like the one in the OP, in working condition for a decent price.
    This thread is too long to review, so are you talking about a Lister engine?

    And if is, is it Limey or Injun built?

    Edit:

    Oh, hell.

    I just reviewed the OP.

    Nevermind.

    Steam, huh?



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  9. #217
    Quote Originally Posted by sparebulb View Post
    This thread is too long to review, so are you talking about a Lister engine?

    And if is, is it Limey or Injun built?

    Edit:

    Oh, hell.

    I just reviewed the OP.

    Nevermind.

    Steam, huh?
    The Limey Listers are going for a small fortune these days, since they have been banned for import by EPA fatwa

    Yup, steam...or the old "make and break engines", those have potential as well.

  10. #218
    Dan Gelbart is a rather interesting fellow. Here is something he threw together in his free time:

    Through lives and lives shalt thou pay, O' king.

    Freedom will be stolen from you in a heartbeat if you do not behave as a wild and ravening beast pursuant to its protection.

    "Government" is naught but a mental construct, a script to which people meekly accept and play out their assigned roles by those with no authority to dictate such.

    Pray for reset.


  11. #219
    Quote Originally Posted by Anti Federalist View Post
    The Limey Listers are going for a small fortune these days, since they have been banned for import by EPA fatwa

    Yup, steam...or the old "make and break engines", those have potential as well.
    You can get the Injun ones, but they require some post purchase fiddling, since to get around the EPA fatwas, they have to be imported as "air compressors" and then the fule system added after the fact.

  12. #220
    Quote Originally Posted by osan View Post
    Dan Gelbart is a rather interesting fellow. Here is something he threw together in his free time:

    Electronic timing on single stage steam engine...fascinating.

    Was this his invention?

  13. #221
    Quote Originally Posted by Anti Federalist View Post
    The Limey Listers are going for a small fortune these days, since they have been banned for import by EPA fatwa

    Yup, steam...or the old "make and break engines", those have potential as well.
    You can get single- and double-lung hit-or-miss engines that are made right here in the USA. Arrow Engines is a primary source. We were to be the sole representatives for sales and service for the states of WV and PA. Gary, my "partner" was one of those perpetually struggling losers who, as it turned out, was more afraid of success than he was covetous of it. Just as I was getting the relationship established with Arrow, that $#@! tells me that things were happening "too fast" and he pulled out, retired, and moved to Florida. $#@!. What pissed me off most was that he asked ME to run the business for him. All that jerkoff had to do was sit back and count money, and it likely would have been substantial amounts. I SO dislike stupid, timid, do-nothing people who shy away from success because it asks of them just a smidge of committed effort.

    My indigestion aside, Arrow makes engines that can run for years, virtually non-stop, and are extremely fuel-efficient.

    You're welcome.
    Through lives and lives shalt thou pay, O' king.

    Freedom will be stolen from you in a heartbeat if you do not behave as a wild and ravening beast pursuant to its protection.

    "Government" is naught but a mental construct, a script to which people meekly accept and play out their assigned roles by those with no authority to dictate such.

    Pray for reset.


  14. #222
    Quote Originally Posted by Anti Federalist View Post
    Electronic timing on single stage steam engine...fascinating.

    Was this his invention?
    I suspect so.
    Through lives and lives shalt thou pay, O' king.

    Freedom will be stolen from you in a heartbeat if you do not behave as a wild and ravening beast pursuant to its protection.

    "Government" is naught but a mental construct, a script to which people meekly accept and play out their assigned roles by those with no authority to dictate such.

    Pray for reset.


  15. #223
    Just seeing this now...nifty, thanks.

  16. #224
    This post discusses low pressure steam engines. I had previously discussed the Terrajoule solar thermal steam engine system which is relevant for operating compounded piston steam engines with very low pressure vacuum condensers. However, I do not believe I discussed Frank Shuman's work during the early 1900's on solar thermal steam engine systems. It is an interesting topic with important implications for anyone interested in small scale steam power.

    Frank Shuman's solar power plant operated at a mechanical power output of about 50 shaft hp. It was set up near Cairo, Egypt and operated an irrigation pump for a short period before being scrapped during the early part of WW1. All accounts I have found suggest it was successful, but poorly timed. Apparently, it was scrapped to provide steel for the war effort. The system was interesting for operating with steam at less than 20 psia. I mentioned in previous posts that small piston steam engines generally do not use low pressure steam efficiently. However, large piston steam engines can do remarkably well.

    The performance data I was able to find shows the engine achieved a high percentage of the theoretical maximum possible performance. With steam on the order of 220F and a vacuum condenser operating at on the order of 100F, the engine required about 25 pounds of steam per shaft hp hour. This corresponds to 85-90% Rankine cycle efficiency. The data on the the solar collector efficiency was less complete. However, I have argued elsewhere that the "efficiency" of a solar power system is a four letter word: COST. When operating at so low a temperature, then it becomes possible to devise a relatively simple system that also sees lower thermal losses - all else equal.
    NOTE: The engine did so well partly because it was a fairly large double acting compounded design which lessens friction losses. Also, the low steam pressure would reduce piston seal leakage, and any leakage past the first stage would continue to the much lower second stage where this leakage would be lower still. Also, the low temperature differentials across the second stage would minimize thermal losses in the slide valve (discusses in a previous post). The engines used by Terrajoule use higher temperatures and pressures with corresponding higher expansion ratios and uniflow exhaust to achieve both a high percentage of maximum possible efficiency and high absolute efficiency (on the order of 27% conversion of heat to shaft work).

    Solar thermal at small scale, even with low cost thermal storage, is hard to justify in world with low cost photovoltaics and batteries that may still be costly, but a helluva lot more compact. So, why am I recounting this information? Mainly for education purposes. Understanding that a simple and extremely reliable two cylinder compounded piston steam engine can show high efficiency on very low pressure steam makes it possible to devise a highly efficient small stationary steam engine system. Yes, I have made the same argument previously, but this helps to explain how.
    Last edited by buenijo; 03-26-2020 at 10:38 AM.
    “The beginning of wisdom is to call things by their proper name.” - Confucius.
    "When plunder becomes a way of life for a group of men living together in society, they create for themselves in the course of time a legal system that authorizes it and a moral code that glorifies it." - Frederic Bastiat
    "Being well adjusted to a sick society is not a measure of health." - Jiddu Krishnamurti



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  18. #225
    I was going to leave a comment about my steam engine project I started, but I decided to start a separate thread on the topic. I had considered many times over the years to start a steam engine project. I always declined primarily because I could not justify the project financially. I am in no better a financial situation today. However, I recently considered various ways to re-purpose existing mass produced components to avoid fabrication costs. I will provide periodic updates in that thread to discuss any worthwhile progress (if any).
    Last edited by buenijo; 03-26-2020 at 09:05 AM.

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