It would need to pump 20,000 litres per minute. There is a large steam engine that used to drive a ship. That could power the compressor.
tweake,
Nov 9, 9:16am
if thats the engine your wanting to mod i think you would be silly to change anything on it. i would either run it off compressed air as mentioned before or connect it to an electric motor. electric motor will need some grunt and reduction boxes. thats a lot of weight to get moving. you might have to open or remove the valves to reduce pumping losses.
tintop,
Nov 9, 9:17am
Its a steam engine. If only one cylinder is operational, and on closedown the working crankpin is at top dead center or bottom dead center, the engine will not restart.
The movie shows that the crankpins are 90/270 degrees offset.
fordz,
Nov 9, 9:21am
In race engines to comply for a class they stop delivering fuel to a cylinder and it becomes a slave cylinder.Take out the plug also. It doesn't matter if the cylinder is not using any fuel because the engine is still balanced. So do that to 3 of your cylinders. Stop the fuel and take the plugs out. Now of the remaining cylinder it is not practical to reduce the stroke but you can reduce the bore fairly easily. Make a smaller piston but keep the weight of the one to took out. That will keep the engine balanced. You can buy spun cast cylinder liners fairly easily and machine them to fit into the block for the small piston. Keep the head the same. The compression ratio will drop a bit and you can add some metal back into the head space by welding. Just check the valves clear when they open and grind some metal away if needed. It is a fairly easy option to undertake if you think about how you are going to do it. All the best, Roger
What does the law of physics say? i cant get my head around what is happening, but without no load, will it make any difference whether the volume / cylinders changes? You are only talking about the energy to move pistons and the associated valves etc. i doubt that changing the volume is going to have any significant energy requirement. You still have all the lost energy in heat etc, whether you are runnig one cylinder or 4.
trade4us2,
Nov 9, 10:20am
It is simply impossible with the present boiler to boil up water fast enough to generate 20,000 litres of steam per minute. If a larger boiler was obtained, that would use even more coal and need some kind of coal feeding system. And coal isn't all that cheap.
skin1235,
Nov 9, 10:54am
it would only use 20,000 lt of steam when working hard, to idle it would use a hell of a lot less, have you actually tried or are you forward planning and got some of the equation wrong, reconsider , it is only under full load that it requires under a 5% load it will require 5% to motor it
the comments re fail to start have not taken into account that that issue was inherent to the design of many engines of that era, single pots were notorious for it, the work around was that there was a starting position that had to align before attempting to charge the cylinder/s
skin1235,
Nov 9, 10:59am
the cost of coal is immaterial, the boiler is not part of the engine, it is remote, or can be remote, if the cost is not the issue simply drop a 20kw diesel boiler out of sight and plumb the steam to the appropriate engine port running it on compressed air will very likely ruin it in a short time, it is not designed for it, the bore lube system is built for water/steam, air will dry it and ruin it, not insurmountable, use a wet air system, but huge cost to setup and cannot be exhausted without treatment
skin1235,
Nov 9, 11:08am
interesting problem though, if the cost of coal is a decider then fuel the boiler with other fuel, which will mean a new boiler, you'll need real figures to show the peak demand and get a boiler capable - but peak will be getting it moving, and once it is moving it may only require 5% of that peak load to continue idling, maybe a diesel engine to get it up to idle speed then switch to lower volume steam - you may even have an old Gardiner doing not a lot other than pulsing away in the corner, combine the two it the one display? the gradiner and a big old gearbox cos the gardiner at full noise is barely 800rpm and you want 15 rpm, if the engine is the one displayed in the link you would simply use a wheel against the rim of the flywheel to get it to 15 rpm then switch to steam - hey even if it degraded over say a 10 minute period to 12 rpm and you then shut it down - display finished
trade4us2,
Nov 9, 11:09am
15 rpm x 1280 litres = 19200 litres per minute when idling
skin1235,
Nov 9, 11:10am
whats the hp rating on it, 20,000lt per minute would say a hell of a lot of hp, its cylinder capacity is 20,000 lt per minute, what was its max pump rate, about 4000 per minute? (20% efficiency)
lugee,
Nov 9, 11:16am
How much steam/gas it needs in a given time is a product of displacement and speed. Nothing to do with power.
As above, 15rpm * 1280 litres = 19,200 litres per minute to get it moving. Anything less than 19,200 and you're going to have a vacuum in the cylinders at the end of a stroke.
skin1235,
Nov 9, 11:18am
but that displacement is doing work, and that has a lot to do with hp
skin1235,
Nov 9, 11:19am
is there a different speed between idle and working, with that sized flywheel I'd seriously doubt it
lugee,
Nov 9, 11:20am
You'd probably need to know what kind of cylinder pressures you're getting to know power. Total piston area times pressure would give you total force put to the crank.
skin1235,
Nov 9, 11:22am
one of the reasons why they used steam was because it continues to expand in the cylinder, the engine pumps out 20,000 ltr per minute when doing 15 rpm, it does not require 20,000 lts of steam into the engine
skin1235,
Nov 9, 11:25am
on a calculator yes, and this engine has a history, somewhere it will be noted what it was capable of pumping - and that pump that was driven by this engine would be interesting too
lugee,
Nov 9, 11:27am
True, then I suppose the expansion coefficient of steam would need to be known, and then the pressure at TDC and BDC, and for how long steam is admitted to the cylinder.
Or just measure it.
skin1235,
Nov 9, 11:34am
the original request was not calculated properly, the 20k capacity is not what the original boiler was putting out, its interesting but wrong, the expansion coefficiency of steam is approx 45% ( I think without checking ) so the original boiler was only putting out barely half the capacity of the cylinders and with an engine that old it may have been using even less live steam than that, perhaps as low as500 lt per minute - of steam - approx 3 ltrs of water per minute into the boiler, plus it was probably only 110 degree, not superheated
skin1235,
Nov 5, 5:26pm
steam = 1600 times the volume of water rings a bell somewhere, not sure of the temp or pressure developed
if that is correct the boiler would consume 12.5 lts of water per minute and that is for complete fill of the cylinder, to utilises steam you use the expansion rate of it, only a small percentage of that 20k lt, the boiler itself could actually be quite small
I'm sure I should know what hp boiler would be required to consume that amount, but its late, I've been working half the night and having a wee wind down before bed lol
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