Force circulation steam generator design
Posted by SteveW
|
Re: Force circulation steam generator design February 14, 2022 12:03PM |
Hi Steve,
Note that I re-attached your concept. I have some questions:
- How are you going to control feed water
- What size/diameter are the tubes? (important to Reynold's No. and Turbulent flow/heat transfer)
- How many MBTU for the burner
- If OK to release, what length of the tubes
- Do you have any size or shape restrictions
- I'm guessing you have a feed pump planned, where would that go
- I'm also guessing you will have a 700*F X 700 PSI expander (rotary machine). If not, what is planned
I'm OK with your layout with one exception. My opinion, I would reverse the Radiant Heat Coils (RHC) with the Superheat Coils (SC). Reason is to keep a consistent temperature gradient. It would appear that the temperature of the RHC will be hotter than SC. Also, there may be something planned that I'm not seeing.
Interesting to talk about, thank you for sharing.
Kind regards,
Rick
Note that I re-attached your concept. I have some questions:
- How are you going to control feed water
- What size/diameter are the tubes? (important to Reynold's No. and Turbulent flow/heat transfer)
- How many MBTU for the burner
- If OK to release, what length of the tubes
- Do you have any size or shape restrictions
- I'm guessing you have a feed pump planned, where would that go
- I'm also guessing you will have a 700*F X 700 PSI expander (rotary machine). If not, what is planned
I'm OK with your layout with one exception. My opinion, I would reverse the Radiant Heat Coils (RHC) with the Superheat Coils (SC). Reason is to keep a consistent temperature gradient. It would appear that the temperature of the RHC will be hotter than SC. Also, there may be something planned that I'm not seeing.
Interesting to talk about, thank you for sharing.
Kind regards,
Rick
|
Re: Force circulation steam generator design February 18, 2022 11:59AM |
Hi Ken,
I think Steve mistake you for me above...it's OK.
I'm curious if you ever ran across a Tesla Flow Valve (check valve) sometimes referred to as a water diode used in a boiler to convert feedwater to circulation? This would be the lose concept. I included a pic for reference.
Can you attach an example of a French inductor (injector) forced circulation?
Thanks,
Rick
I think Steve mistake you for me above...it's OK.
I'm curious if you ever ran across a Tesla Flow Valve (check valve) sometimes referred to as a water diode used in a boiler to convert feedwater to circulation? This would be the lose concept. I included a pic for reference.
Can you attach an example of a French inductor (injector) forced circulation?
Thanks,
Rick
|
Re: Force circulation steam generator design February 18, 2022 01:45PM |
Hi Rick,
Attached is the image for the Endurance steam system. The actual pump is only shown in schematic in the system drawings. Those drawings were black and white, poorly drawn and suffering from poor reproduction -- so I had to redo them on CAD and add color. Then I had to resize it to fit the Forum upload limit. You can see the feed pump is laid out horizontally and does double duty as its step-piston also acts as a vacuum pump for the fuel system.
To the top of the feed pump discharge is the circulation pump. The circulation pump valves and spring are mounted on top of the larger cylinder. The mechanism on the bottom regulates feed water flow, it is a diaphragm device that acts as an unloader valve for the feed pump.
The feed pump discharge goes through the boiler economizer and early stage heating coils before heading to the eductor -- this preheating causes the water to expand and increases flow velocity -- improving eductor performance. This flow is combined with the circulation pump discharge which also powers the eductor. The eductor output is then directed to the evaporator coil, this being a forced recirculation boiler.
This is the most advanced steam car system of which I am aware. The burner is blower driven, but vaporizing instead of atomizing. The burner design is very simple, being the recipient of a number of generations of refinement and simplification over prior burners. There is an electrical vaporizer in the burner meant to provide a small amount of vaporized fuel just for starting from cold and for supplying the pilot. An auxiliary steam engine drives the blower, fuel and water pumps plus condenser cooling fan -- once lit off the steam system was isolated from the vagaries of the main steam engine and could therefore cruise easily on a flat road or two a heavy load up a mountain without badly affecting the steam temperature and pressure. Both the main and auxiliary engines are uniflow, the fuel delivery is carbureted to maintain a relatively constant mixture. Two prototype Endurance steam cars went from California to Washington DC, in different years, in the mid 20s. They managed the feat at about the same rate of speed as gasoline cars of the day... Considering that they were meeting investors along the way, this was impressive. .This would be an impressive feat for steam cars today, even though roads are far superior.
I'm familiar with the fluidic diode and have considered it as a means of improving boiler circulation -- the check valve acting somewhat like the check valve in a pulse jet engine to establish one way flow. The Tesla valve is sort of restrictive and there are superior designs floating around, some used in nuclear reactors. The problem is that fluidic diode performance is not like a real check valve. Under certain conditions they work fairly well, though they do not entirely prohibit backflow. At lower circulation rates their effectiveness starts to drop off, dramatically. This isn't an issue in a generating plant where load is pretty constant but might not be as suitable in automotive applications.
Regards,
Ken
Attached is the image for the Endurance steam system. The actual pump is only shown in schematic in the system drawings. Those drawings were black and white, poorly drawn and suffering from poor reproduction -- so I had to redo them on CAD and add color. Then I had to resize it to fit the Forum upload limit. You can see the feed pump is laid out horizontally and does double duty as its step-piston also acts as a vacuum pump for the fuel system.
To the top of the feed pump discharge is the circulation pump. The circulation pump valves and spring are mounted on top of the larger cylinder. The mechanism on the bottom regulates feed water flow, it is a diaphragm device that acts as an unloader valve for the feed pump.
The feed pump discharge goes through the boiler economizer and early stage heating coils before heading to the eductor -- this preheating causes the water to expand and increases flow velocity -- improving eductor performance. This flow is combined with the circulation pump discharge which also powers the eductor. The eductor output is then directed to the evaporator coil, this being a forced recirculation boiler.
This is the most advanced steam car system of which I am aware. The burner is blower driven, but vaporizing instead of atomizing. The burner design is very simple, being the recipient of a number of generations of refinement and simplification over prior burners. There is an electrical vaporizer in the burner meant to provide a small amount of vaporized fuel just for starting from cold and for supplying the pilot. An auxiliary steam engine drives the blower, fuel and water pumps plus condenser cooling fan -- once lit off the steam system was isolated from the vagaries of the main steam engine and could therefore cruise easily on a flat road or two a heavy load up a mountain without badly affecting the steam temperature and pressure. Both the main and auxiliary engines are uniflow, the fuel delivery is carbureted to maintain a relatively constant mixture. Two prototype Endurance steam cars went from California to Washington DC, in different years, in the mid 20s. They managed the feat at about the same rate of speed as gasoline cars of the day... Considering that they were meeting investors along the way, this was impressive. .This would be an impressive feat for steam cars today, even though roads are far superior.
I'm familiar with the fluidic diode and have considered it as a means of improving boiler circulation -- the check valve acting somewhat like the check valve in a pulse jet engine to establish one way flow. The Tesla valve is sort of restrictive and there are superior designs floating around, some used in nuclear reactors. The problem is that fluidic diode performance is not like a real check valve. Under certain conditions they work fairly well, though they do not entirely prohibit backflow. At lower circulation rates their effectiveness starts to drop off, dramatically. This isn't an issue in a generating plant where load is pretty constant but might not be as suitable in automotive applications.
Regards,
Ken
|
Re: Force circulation steam generator design February 21, 2022 12:09PM |
Thanks Ken,
I second the motion, nice job with CAD. I also agree that it is one of the best Rankine Systems designed. It is hard to beat the circulation system using the inductor in synergy with other functions.
Perhaps I'll get around to showing how I would use the fluid diode on an Ofeldt. Respectfully, I know you're not to keen on the Ofeldt. However, the idea is to turn the natural circulation into a multi-path tube boiler with the addition of albeit a check valve. Perhaps that might find some favor in your thinking.
I'm still busy getting my shop insulated and up to speed for building steam stuff.
Very best,
Rick
I second the motion, nice job with CAD. I also agree that it is one of the best Rankine Systems designed. It is hard to beat the circulation system using the inductor in synergy with other functions.
Perhaps I'll get around to showing how I would use the fluid diode on an Ofeldt. Respectfully, I know you're not to keen on the Ofeldt. However, the idea is to turn the natural circulation into a multi-path tube boiler with the addition of albeit a check valve. Perhaps that might find some favor in your thinking.
I'm still busy getting my shop insulated and up to speed for building steam stuff.
Very best,
Rick
|
Re: Force circulation steam generator design February 24, 2022 06:59AM |
Hi Rick,
I think it's safest if we consider the Ofeldt, and any number of similar boilers, to be "percolators" rather than natural circulation. The big marine boilers with which I was familiar in the Navy had upper and lower drums connected by a multiplicity of tubes, with both the downcomers and circulation tubes being fully submerged at all times. The difference in the weight of water in both tubes caused the circulation. The thing to remember is that these suckers are big and the vertical height provides enough difference in pressure to force a vigorous flow. Cars, being the compact little wonders that they are, simply can't match the natural circulation. Percolators, on the other hand, have a completely submerged downcomer section but the circulation tubes exit into the steam space. As steam generates in the tubing, it spurts in the direction of least resistance, just like a percolator. This method gives you pretty vigorous circulation in a small unit, the only downside (if we can even call it that) being that the flow is intermittent rather than perfectly continuous.
Going back to the Endurance steamer, we see a few features that the Ofeldt (and similar boilers) lack -- and this can include units like the Stanley. The first of these is counterflow heat exchange. The hot fluid rises and the hot gasses are forced downwards by the blower, thus the hottest steam is closest to the flame and the coldest feedwater is near the flue -- which results in the highest heat transfer efficiency (see attachment). This is precisely why Abner Doble also put his burner on top. The problem is that hot fluids rise and both the water in the boiler and the combustion gasses from the burner want to travel in the same direction. This is why Rollin White put those funny loops over the top of his coil stack. He had a vaporizing burner at the bottom of his steam generator and wanted to force the flow from top to bottom. He was worried that steam in the generator would want to flow upwards, even as he was forcing the water downwards.Those loops at the top of his boiler were actually loop seals, which allowed him to force both steam and water downwards simultaneously. So, if we have both White and Doble both pushing the flow at the burner, we have to conclude it's the right thing to do.
The other thing we need to keep in mind with recirculation boilers, be they forced, natural circulation or percolators, is that only a fraction of the flow through the boiler at any given time will consist of steam. Since the steam and water are in constant contact, however, we have to conclude that the water is at saturation temperature up until the point that cooler feed water enters the boiler. This is all well and good, we like this because we can get more steam production per square foot of generating tube if the water is at saturation. The problem is that heat exchange is proportional to temperature difference and combustion gasses can transfer more heat to a cooler surface than they can to a hotter one -- which is precisely why those naval boilers, and the Endurance, have large economizer sections through which only feed water travels. We don't really get the same effect by injecting cool feed into the circulation loop because the feed is only a fraction of the mass, the temperature drop it induces is mild. If the proposed economizers are comprised of finned tube, we can keep the weight down and also greatly reduce the pressure drop through the section. Of course, we have to keep counterflow in mind when orienting the economizer with the inlet being right at the flue.
Now, if you could rework an Ofeldt (or other percolators and natural flow boilers) so that the burner was on top and there was an economizer at the bottom, we should see a bump in efficiency.
Beyond all that, water in the economizer expands as it heats, and this is much greater in the generating tubes as steam is produced. Both effects increase flow velocity. Anything that can be done to preserve this velocity during the recirculation would undoubtedly also improve the effectiveness of the boiler due to an increased Reynolds number and perhaps permit a reduction in size.
Now, keep in mind, I don't think any of this is naturally applicable to a boiler being used in a traditional sort of format. In those cases, you tend to want to emulate the feel of what was originally employed. On the other hand, if you are simply trying to build a modern unit, efficiency becomes important and the use of economizers and counterflow starts to look important.
Regards,
Ken
I think it's safest if we consider the Ofeldt, and any number of similar boilers, to be "percolators" rather than natural circulation. The big marine boilers with which I was familiar in the Navy had upper and lower drums connected by a multiplicity of tubes, with both the downcomers and circulation tubes being fully submerged at all times. The difference in the weight of water in both tubes caused the circulation. The thing to remember is that these suckers are big and the vertical height provides enough difference in pressure to force a vigorous flow. Cars, being the compact little wonders that they are, simply can't match the natural circulation. Percolators, on the other hand, have a completely submerged downcomer section but the circulation tubes exit into the steam space. As steam generates in the tubing, it spurts in the direction of least resistance, just like a percolator. This method gives you pretty vigorous circulation in a small unit, the only downside (if we can even call it that) being that the flow is intermittent rather than perfectly continuous.
Going back to the Endurance steamer, we see a few features that the Ofeldt (and similar boilers) lack -- and this can include units like the Stanley. The first of these is counterflow heat exchange. The hot fluid rises and the hot gasses are forced downwards by the blower, thus the hottest steam is closest to the flame and the coldest feedwater is near the flue -- which results in the highest heat transfer efficiency (see attachment). This is precisely why Abner Doble also put his burner on top. The problem is that hot fluids rise and both the water in the boiler and the combustion gasses from the burner want to travel in the same direction. This is why Rollin White put those funny loops over the top of his coil stack. He had a vaporizing burner at the bottom of his steam generator and wanted to force the flow from top to bottom. He was worried that steam in the generator would want to flow upwards, even as he was forcing the water downwards.Those loops at the top of his boiler were actually loop seals, which allowed him to force both steam and water downwards simultaneously. So, if we have both White and Doble both pushing the flow at the burner, we have to conclude it's the right thing to do.
The other thing we need to keep in mind with recirculation boilers, be they forced, natural circulation or percolators, is that only a fraction of the flow through the boiler at any given time will consist of steam. Since the steam and water are in constant contact, however, we have to conclude that the water is at saturation temperature up until the point that cooler feed water enters the boiler. This is all well and good, we like this because we can get more steam production per square foot of generating tube if the water is at saturation. The problem is that heat exchange is proportional to temperature difference and combustion gasses can transfer more heat to a cooler surface than they can to a hotter one -- which is precisely why those naval boilers, and the Endurance, have large economizer sections through which only feed water travels. We don't really get the same effect by injecting cool feed into the circulation loop because the feed is only a fraction of the mass, the temperature drop it induces is mild. If the proposed economizers are comprised of finned tube, we can keep the weight down and also greatly reduce the pressure drop through the section. Of course, we have to keep counterflow in mind when orienting the economizer with the inlet being right at the flue.
Now, if you could rework an Ofeldt (or other percolators and natural flow boilers) so that the burner was on top and there was an economizer at the bottom, we should see a bump in efficiency.
Beyond all that, water in the economizer expands as it heats, and this is much greater in the generating tubes as steam is produced. Both effects increase flow velocity. Anything that can be done to preserve this velocity during the recirculation would undoubtedly also improve the effectiveness of the boiler due to an increased Reynolds number and perhaps permit a reduction in size.
Now, keep in mind, I don't think any of this is naturally applicable to a boiler being used in a traditional sort of format. In those cases, you tend to want to emulate the feel of what was originally employed. On the other hand, if you are simply trying to build a modern unit, efficiency becomes important and the use of economizers and counterflow starts to look important.
Regards,
Ken
|
Re: Force circulation steam generator design February 25, 2022 11:32AM |
I have posted most of this before on previous post or another but through it might be a good reminder now.
Some thoughts on boiler design.
Laminar verses turbulent flow in more relevant to the flow of gasses thorough the tubing bank after leaving the combustion chamber. Raytheon in there extensive study on cooling radar tubes found that turbulent flow of gases around pipe or tube did four times more work then Laminar flow of gases. Heat radiates in all direction at the same speed of light in the combustion chamber and generator bank. Hot gases on the other hand are controlled by the burner pressure and tube configuration. Wrapping the combustion chamber with the appropriate size pipe with forced circulation water has the highest differential in temperature, and does more work then any other location in the steam generator, being at a higher pressure then generator pressure by the forced pump there should be little on no steam bubbles generated in this tube till the water gets back to the main drum that is at a lower pressure. It is my opinion in a 200 HP generator this coil should be at min one inch ID.
From the combustion chamber the hot gases flow in either laminar flow or turbulent flow based on the tube layout and winding configuration. The winding pattern in a wound coil generator should be wound so the gases flow through the bank in a turbulent pattern to achieve the highest output of a coiled generator, reducing the overall size of the tube bank and size of the generator. Turbulent flow coil windings can be as close as one-quarter-tube diameter to each other. Of course this will increases combustion chamber pressure and require higher HP burner. I don’t think I have ever achieved the correct combustion chamber pressure as I have had many combustion chamber explosions.
The choice has to be made as to the burner firing method, straight in or tangential. I have used both but tangential with a combustion chamber liner seams to me to have a much cleaner burn and controlled fire. If tangential you should be aware or your running location for as clock wise or counter clock wise firing.
The preferred material and by the ASME code for most boilers and generator tube is low carbon steel ASTM SA-178 grade A C= 0.18 and A-106 is also excepted grade A C= 0.25 Max
Steel plate common for ASTM for boiler construction is SA-285, SA-515 & SA-516
Rolly
Some thoughts on boiler design.
Laminar verses turbulent flow in more relevant to the flow of gasses thorough the tubing bank after leaving the combustion chamber. Raytheon in there extensive study on cooling radar tubes found that turbulent flow of gases around pipe or tube did four times more work then Laminar flow of gases. Heat radiates in all direction at the same speed of light in the combustion chamber and generator bank. Hot gases on the other hand are controlled by the burner pressure and tube configuration. Wrapping the combustion chamber with the appropriate size pipe with forced circulation water has the highest differential in temperature, and does more work then any other location in the steam generator, being at a higher pressure then generator pressure by the forced pump there should be little on no steam bubbles generated in this tube till the water gets back to the main drum that is at a lower pressure. It is my opinion in a 200 HP generator this coil should be at min one inch ID.
From the combustion chamber the hot gases flow in either laminar flow or turbulent flow based on the tube layout and winding configuration. The winding pattern in a wound coil generator should be wound so the gases flow through the bank in a turbulent pattern to achieve the highest output of a coiled generator, reducing the overall size of the tube bank and size of the generator. Turbulent flow coil windings can be as close as one-quarter-tube diameter to each other. Of course this will increases combustion chamber pressure and require higher HP burner. I don’t think I have ever achieved the correct combustion chamber pressure as I have had many combustion chamber explosions.
The choice has to be made as to the burner firing method, straight in or tangential. I have used both but tangential with a combustion chamber liner seams to me to have a much cleaner burn and controlled fire. If tangential you should be aware or your running location for as clock wise or counter clock wise firing.
The preferred material and by the ASME code for most boilers and generator tube is low carbon steel ASTM SA-178 grade A C= 0.18 and A-106 is also excepted grade A C= 0.25 Max
Steel plate common for ASTM for boiler construction is SA-285, SA-515 & SA-516
Rolly
|
Re: Force circulation steam generator design February 25, 2022 12:08PM |
Hi Steve,
Back to your steam gen design concept. What Rolly and I are suggesting is that you will get the most bang for the buck if you plan on forcing the hot gas burner flow through the set path at the fastest rate you can.
Next best bang for the buck is to force the water through the tube path the fastest rate you can. This has to be a consideration of tube diameter and length. The attached video uses 3/16 brake line as a monotube boiler, flash boiler. Think about how fast you would need to force water through that tube to supply 200 HP. Perhaps not practical but consider the trade off of Diameter-length to steam amount of lbs/hr steam. What you see in the video is in the neighborhood of 8 HP. A good starting point is the Doble boiler design.
Hydroplane boat steam speed record
I re-attached your concept so one doesn't have to scroll back and forth. Both suggestions are considering the highest Reynolds No. possible which correlates to the greatest heat transfer.
Hi Rolly,
You do pretty good for working out of the library computer my friend.
I like the tangential burner design. I know a gentleman whom I consult to who will be interested in this tangential burner design. He has just built an Ofeldt and putting it into his condensing Stanley. Some of you reading this might know who I'm talking about. He posts on Facebook often. I'm advising him on a burner configuration and suggested just this concept. However, your attached picture shows an excellent method.
Kind regards,
Rick
Back to your steam gen design concept. What Rolly and I are suggesting is that you will get the most bang for the buck if you plan on forcing the hot gas burner flow through the set path at the fastest rate you can.
Next best bang for the buck is to force the water through the tube path the fastest rate you can. This has to be a consideration of tube diameter and length. The attached video uses 3/16 brake line as a monotube boiler, flash boiler. Think about how fast you would need to force water through that tube to supply 200 HP. Perhaps not practical but consider the trade off of Diameter-length to steam amount of lbs/hr steam. What you see in the video is in the neighborhood of 8 HP. A good starting point is the Doble boiler design.
Hydroplane boat steam speed record
I re-attached your concept so one doesn't have to scroll back and forth. Both suggestions are considering the highest Reynolds No. possible which correlates to the greatest heat transfer.
Hi Rolly,
You do pretty good for working out of the library computer my friend.
I like the tangential burner design. I know a gentleman whom I consult to who will be interested in this tangential burner design. He has just built an Ofeldt and putting it into his condensing Stanley. Some of you reading this might know who I'm talking about. He posts on Facebook often. I'm advising him on a burner configuration and suggested just this concept. However, your attached picture shows an excellent method.
Kind regards,
Rick
|
Re: Force circulation steam generator design February 28, 2022 06:39AM |
And, of course, you can always lay a boiler down sideways, if it helps with installation. The Newcomb boiler was a pretty amazing design circa 1901, or so. The fuel/air mixture came down a central tube so that the fuel was preheated and vaporized when passing through the flame holder. The conico-frustrum coils meant that you could get more surface area by winding fewer coils -- and it allowed you to stack identical coils like pancakes whereas each helical coil would have to be a different diameter. The flow through the boiler is counterflow.
SES was an extremely high output, extremely compact boiler from the 1970s. It also had the central tube, albeit larger because the fan could push a lot more air than the vaporized fuel jet could manage in Newcomb's day -- it still used the flameholder. The flow was almost counterflow -- the coil closest to the fire did not function as a superheater. They called it the "quench coil" and its job was to lower the flame temperature so as to reduce the amount of nitrous oxides produced.
The SES was mounted as shown, the Newcomb actually has the burner on the bottom but I rotated it 90 degrees because I was comparing and contrasting the two machines. Also note that SES has far fewer coils, despite far higher output. If you will look carefully, you will see that some of the coils are finned and the surface area goes up by something like a factor of 10. (Edit -- I should have mentioned that SES also has exhaust gas recirculation -- obviously reduced emissions were part of the design goals.)
The McInerney patent is interesting because he sort of refutes the counterflow argument. Actually, he doesn't do that at all. He is a firm believer in "hot to hot, cold to cold". What McInerney found was that the fluid running through a monotube would actually start to cool off in the area where steam generation was high. What appears to be happening is that there is some time delay in the formation of steam and therefore the water is briefly in a supersaturated state. When steam does form, it absorbs heat from the surrounding water and tube wall in order to supply latent heat of vaporization. Therefore, in order to obtain best heat transfer by maintaining counterflow, McInerney causes the tube to travel towards the flue as the contents were cooling off. This was an interesting patent in that I don't believe anyone had ever noticed this phenomenon previously -- I assume that boiler looked like a porcupine with all the thermocouples sticking out of it. Now, I had to read the patent something like three times to figure this all out. Vapor Corp. sort of hid this information inside a lot of other verbiage describing the boiler and didn't go to great lengths to spell it out. I'm assuming that they didn't want competitors to know so they sort of hid it in plain sight under a layer of gobbledegook...
Regards,
Ken
Edited 2 time(s). Last edit at 02/28/2022 08:10AM by frustrated.
SES was an extremely high output, extremely compact boiler from the 1970s. It also had the central tube, albeit larger because the fan could push a lot more air than the vaporized fuel jet could manage in Newcomb's day -- it still used the flameholder. The flow was almost counterflow -- the coil closest to the fire did not function as a superheater. They called it the "quench coil" and its job was to lower the flame temperature so as to reduce the amount of nitrous oxides produced.
The SES was mounted as shown, the Newcomb actually has the burner on the bottom but I rotated it 90 degrees because I was comparing and contrasting the two machines. Also note that SES has far fewer coils, despite far higher output. If you will look carefully, you will see that some of the coils are finned and the surface area goes up by something like a factor of 10. (Edit -- I should have mentioned that SES also has exhaust gas recirculation -- obviously reduced emissions were part of the design goals.)
The McInerney patent is interesting because he sort of refutes the counterflow argument. Actually, he doesn't do that at all. He is a firm believer in "hot to hot, cold to cold". What McInerney found was that the fluid running through a monotube would actually start to cool off in the area where steam generation was high. What appears to be happening is that there is some time delay in the formation of steam and therefore the water is briefly in a supersaturated state. When steam does form, it absorbs heat from the surrounding water and tube wall in order to supply latent heat of vaporization. Therefore, in order to obtain best heat transfer by maintaining counterflow, McInerney causes the tube to travel towards the flue as the contents were cooling off. This was an interesting patent in that I don't believe anyone had ever noticed this phenomenon previously -- I assume that boiler looked like a porcupine with all the thermocouples sticking out of it. Now, I had to read the patent something like three times to figure this all out. Vapor Corp. sort of hid this information inside a lot of other verbiage describing the boiler and didn't go to great lengths to spell it out. I'm assuming that they didn't want competitors to know so they sort of hid it in plain sight under a layer of gobbledegook...
Regards,
Ken
Edited 2 time(s). Last edit at 02/28/2022 08:10AM by frustrated.
|
Re: Force circulation steam generator design March 03, 2022 07:50AM |
Attached find a drastically over-simplified drawing I did up for the Endurance steam car burner. The fuel/air mixture passes into the central vaporizer tunnel, which is essentially a rectangular box with a pair of doors situated at the far end from the induction tube. The fuel/air mix passes through these two doors and then reverses course as it flows through the two side wings. Each of these wings has a slitted bottom surface which acts as a flame holder, the fuel/air mixture passes through these slits before it is ignited by either spark plug or pilot. Obviously, this is a downwards blowing unit. The vaporizer tunnel, being exposed to both radiant and convective heat, gets quite hot. It is, however, cooled by the volume of air passing through. We can classify the fuel suspended in the fuel/air mixture into two categories, that in which the droplets stay in suspension and that in which the droplets fall out of suspension and rest on the floor of the vaporizer tunnel. That in suspension is vaporized by convection as heat rises off of the vaporizing tunnel floor. The droplets falling out of suspension rest directly on the vaporizer tunnel floor and are also vaporized.
My own personal experience indicates that the fuel vaporization absorbs an amazing amount of heat, and this probably protects the relatively thin sheet metal burner. I built an SES style burner, which uses the same principles, and ran into an interesting phenomenon. On a hot summer's day (over 90 degrees), I noticed condensate forming on the tube between the carburetor and the blower (I was drawing air through the carb into the three stage blower). The gasoline was vaporizing in the low pressure area, and absorbing so much heat in the process that it made the tube cool to the touch. As it was, I was still not getting anything like complete vaporization and had to route the drip-off fuel through a coil surrounding the burner and reintroduce it at the blower suction. It had never occurred to me that I was building a rudimentary air conditioning unit.
Anyhow, most fan style blowers are atomizing and do not tend to burn quite as cleanly. Both the Endurance and the SES are vaporizing, blue-flame burners. French built a number of fan-driven blue flame burners prior to this, such as in the International Harvester tractor and the Coats steam car. The big difference was that those were elaborate whereas the Endurance burner was quite simple -- it appears that he managed to refine the concept to its basics and eliminate all the excess mechanism.
The big difference in the blue flame from my burner and a Stanley was that the blower produced a far more intense fire -- rather than being a bed of flame, it produced dozens of points of flame, each of these much like you would find on a gas welder. I am sure part of this was due to the high air pressures developed by the 3 stage blower ... but it explained how SES managed to develop so much more heat than a Stanley in a much smaller package. I was firing it horizontally and chips started exploding off of the driveway as water trapped in the concrete flashed into steam.
In any case, I don't think I've found a more sophisticated or elegant steam car burner than this one.
My own personal experience indicates that the fuel vaporization absorbs an amazing amount of heat, and this probably protects the relatively thin sheet metal burner. I built an SES style burner, which uses the same principles, and ran into an interesting phenomenon. On a hot summer's day (over 90 degrees), I noticed condensate forming on the tube between the carburetor and the blower (I was drawing air through the carb into the three stage blower). The gasoline was vaporizing in the low pressure area, and absorbing so much heat in the process that it made the tube cool to the touch. As it was, I was still not getting anything like complete vaporization and had to route the drip-off fuel through a coil surrounding the burner and reintroduce it at the blower suction. It had never occurred to me that I was building a rudimentary air conditioning unit.
Anyhow, most fan style blowers are atomizing and do not tend to burn quite as cleanly. Both the Endurance and the SES are vaporizing, blue-flame burners. French built a number of fan-driven blue flame burners prior to this, such as in the International Harvester tractor and the Coats steam car. The big difference was that those were elaborate whereas the Endurance burner was quite simple -- it appears that he managed to refine the concept to its basics and eliminate all the excess mechanism.
The big difference in the blue flame from my burner and a Stanley was that the blower produced a far more intense fire -- rather than being a bed of flame, it produced dozens of points of flame, each of these much like you would find on a gas welder. I am sure part of this was due to the high air pressures developed by the 3 stage blower ... but it explained how SES managed to develop so much more heat than a Stanley in a much smaller package. I was firing it horizontally and chips started exploding off of the driveway as water trapped in the concrete flashed into steam.
In any case, I don't think I've found a more sophisticated or elegant steam car burner than this one.
Sorry, only registered users may post in this forum.
