Someone smarter than me, steam question
Someone smarter than me, steam question
"Someone smarter than me", translates to "Everyone on this board"! I have a steam question. My engine has a 2 1/4" bore and a 2 1/4" stroke. Running at 200 RPM at 75lbs pressure, how much water will it use per minute?
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Lopez Mike
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Re: Someone smarter than me, steam question
I (and others!) have asked this question several times. Here is a cut and past of Ron Fossum's reply. Modify the data for your case, of course.
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Determine the amount of water (in the form of steam) that is consumed in one hour operation of the engine:
Bore = 3"
Stroke = 5"
RPM = 300
Steam Pressure = 100 psi gauge
HP=5
Volume of piston (in cubic inches) in one revolution (two strokes) times RPMs times 60 (minutes in an hour) divided by 1728 (number of cu.in. in a cu.ft.), divided by 3.881 (number of cu.ft. of steam per pound of water at 100 psi) divided by 8.34 (pounds of water per gallon of water):
{[(1.5" x 1.5") x Pi x 5" x 2 x 300 x 60] / 1728} / 3.881 (=189.72lbs/hr) / 8.34 = 22.78 gal/hr.
All of the above assumes the admission of steam for the full stroke (90%), usual valve and gland leakage, cylinder condensation, etc. This amounts to about 37.9 lbs. steam/water per HP hour which is a decent figure for a small single cylinder engine with no real variable cutoff (I assume the reverse is by slip eccentric).
Since there are 7.4805 gal/cu.ft. of a liquid, then you need 3.045... cubic feet or 5262.2 cubic inches of water an hour.
If your plunger/ram pump (the best choice by the way for a feedwater pump, particularly if running around 200 strokes per minute or less) is 0.625" plunger diameter by 2 inch stroke, then:
(.3125" x .3125") x Pi x 2" = 0.6135... cu.in. per stroke or 8576 strokes per hour or 143 strokes per minute. Generally 1.5 times the amount of feedwater required is considered best for the pumped supply (allows for whistle blowing, providing steam for tea or espresso machine, catch-up if the water level is low, etc) then you pump would need to make 215 strokes per minute. Nicely within all the parameters.
The above calculations and "rules of thumb" follow the best marine steam practice for small marine engines. They are reasonably accurate.
_________________
Ron Fossum
Steamboating Magazine Editor
http://www.steamboating.org
========
Determine the amount of water (in the form of steam) that is consumed in one hour operation of the engine:
Bore = 3"
Stroke = 5"
RPM = 300
Steam Pressure = 100 psi gauge
HP=5
Volume of piston (in cubic inches) in one revolution (two strokes) times RPMs times 60 (minutes in an hour) divided by 1728 (number of cu.in. in a cu.ft.), divided by 3.881 (number of cu.ft. of steam per pound of water at 100 psi) divided by 8.34 (pounds of water per gallon of water):
{[(1.5" x 1.5") x Pi x 5" x 2 x 300 x 60] / 1728} / 3.881 (=189.72lbs/hr) / 8.34 = 22.78 gal/hr.
All of the above assumes the admission of steam for the full stroke (90%), usual valve and gland leakage, cylinder condensation, etc. This amounts to about 37.9 lbs. steam/water per HP hour which is a decent figure for a small single cylinder engine with no real variable cutoff (I assume the reverse is by slip eccentric).
Since there are 7.4805 gal/cu.ft. of a liquid, then you need 3.045... cubic feet or 5262.2 cubic inches of water an hour.
If your plunger/ram pump (the best choice by the way for a feedwater pump, particularly if running around 200 strokes per minute or less) is 0.625" plunger diameter by 2 inch stroke, then:
(.3125" x .3125") x Pi x 2" = 0.6135... cu.in. per stroke or 8576 strokes per hour or 143 strokes per minute. Generally 1.5 times the amount of feedwater required is considered best for the pumped supply (allows for whistle blowing, providing steam for tea or espresso machine, catch-up if the water level is low, etc) then you pump would need to make 215 strokes per minute. Nicely within all the parameters.
The above calculations and "rules of thumb" follow the best marine steam practice for small marine engines. They are reasonably accurate.
_________________
Ron Fossum
Steamboating Magazine Editor
http://www.steamboating.org
If you think you are too small to make a difference, try sleeping with a mosquito.
Dalai Lama
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fredrosse
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Re: Someone smarter than me, steam question
"Someone smarter than me", translates to "Everyone on this board"! I have a steam question. My engine has a 2 1/4" bore and a 2 1/4" stroke. Running at 200 RPM at 75lbs pressure, how much water will it use per minute?
Smarter is not true, just some of us have had training in specialty areas, and have experience with this class of machinery.
2-1/4 Bore x 2-1/4 Stroke, 200RPM 75 Pounds INLET STEAM
Some additional assumptions needed: A double acting single cylinder engine, with cutoff valve gear at 65% stroke, a typical good value for a slide valve engine. Inlet steam 75 PSIG = 90 PSIA, Non condensing service, atmospheric exhaust pressure.
Putting this into the computer gives a net output of about 1/2 horsepower, and a steam consumption of about 42 PPH (pounds per hour), or 0.691 pounds per minute.
Usually feedwater pumps have additional capacity, to account for running with longer cutoff, blowdown, steam consumption of auxiliaries, etc. It would probably be a good idea for the feedwater pump to be designed to pump 1 pound per minute.
One pound per minute is 60 pounds per hour, and cool water is 62.4 pounds per cubic foot, so very nearly 1 cubic foot per hour, with a reasonable margin for extra capacity requirements.
Smarter is not true, just some of us have had training in specialty areas, and have experience with this class of machinery.
2-1/4 Bore x 2-1/4 Stroke, 200RPM 75 Pounds INLET STEAM
Some additional assumptions needed: A double acting single cylinder engine, with cutoff valve gear at 65% stroke, a typical good value for a slide valve engine. Inlet steam 75 PSIG = 90 PSIA, Non condensing service, atmospheric exhaust pressure.
Putting this into the computer gives a net output of about 1/2 horsepower, and a steam consumption of about 42 PPH (pounds per hour), or 0.691 pounds per minute.
Usually feedwater pumps have additional capacity, to account for running with longer cutoff, blowdown, steam consumption of auxiliaries, etc. It would probably be a good idea for the feedwater pump to be designed to pump 1 pound per minute.
One pound per minute is 60 pounds per hour, and cool water is 62.4 pounds per cubic foot, so very nearly 1 cubic foot per hour, with a reasonable margin for extra capacity requirements.
Re: Someone smarter than me, steam question
Thank you, so much for the information! I'm shopping for an injector.