Hello

Can anyone help me with some data on boiler steaming rates in the US? I am looking for an example or examples of locomotive firetube boilers with a rating of around 100,000lb of steam per hour?

Thanks,

Hi Martyn - I don't know exactly what it is you seek; here's some basic information from Baldwin about evaporation rates:

Direct heating surfaces (firebox, combustion chamber, syphons, arch tubes etc) 55 lbs H2O / hour / square foot.

Indirect (tubes, flues) dependent on length of tube. 10 foot tubes 13 lbs / hr. 15 foot, 10.9. 20 foot, 9.2. 24 foot, 8.2. There's half foot increments listed between the 10 and 24 lengths.

I've got a whole table relating to the additional impact of various types of superheaters on the results.

Note this is for pounds of water, not pounds of steam.

If this doesn't help, please be more specific about what you need to know.

dave

Dave,
What is the diameter of the tubes for the data you listed?
Is that Baldwin data available online?

Hey Max - diameter not listed, since the transfer is based on quuare feet of tube surface, not linear feet of tube....but if you're anywhere near 2" it will work fine, and it also applies to superheater flues so my guess is it's a very ballparkish figure not taking such things as hot gas transition rate and so forth into consideration.

I have no idea if it's online anywhere. I have a bunch of old books and occasionally I can find the right one when I need it.

dave

Hello Dave - That's not quite what I'm looking for. Those figures you quote will vary with combustion and exhaust systems.

What I am looking for is for a given type of loco the rated continuous steam output, ideally in lb of steam per hour. Over here controlled tests came up with such numbers for various types of locos. A lot of testing was done at a defined steaming rate. I have found reference to a PRR Q2 boiler producing 137,500 lb per hour on test.

Maybe nothing much exists but an example of a loco type (advanced or otherwise) with a rated boiler output of 100,000 lb per hour would be nice to have for something I am doing.

I think you might find what you are looking for best as the results of tests rather than as theoretical design calculations. PRR had the Altoona test plant, at which almost any parameter could be quantified. I don't know of the N&W who built exceptionally good steam or Lima who built superpower steam had similar test plants, or did testing in some other way.....but that's where I'd start looking. Advanced steam design must have also had some advanced form of testing involved.

dave

Pounds of water boiled equals pounds of steam produced in any boiler. What you do with that saturated steam makes all the difference because using the steam is a volumetric process.

Pounds of water doesn't equal pounds of steam because of the about 1000 BTU/pound of water it takes to convert water to steam.

For what you are trying to do, I suggest you dig out a thermodynamics text.

You might try Google Books for a free older text. Some of the older texts have some simplified equations that would probably be close enough for your purposes.

Martyn,

I may have some info at home- if so, I'll post tonight.

Based on an article in Trains magazine many years ago, the best U.S. 4-8-4's could produce around 100,000 lbs/hour. Off-hand, I'd say this would include the NYC Niagaras, the N&W J's, the Sante Fe's newest 4-8-4's, and perhaps the Western Maryland 4-8-4's, and the C&O J-3a's (there are probably others). Some of the larger U.S. articulateds could probably exceed 100,000 lbs by a considerable margin.

One pound of water ALWAYS equals one pound of steam. This fact follows the Law of Conservation of Mass. Also one pound of water when frozen will create one pound of ice.

A steaming rate of 100,00 lbs/hour mean about 200 gallons of water per minute being evaporated into steam. While I do not have the number at my fingertips I know it means only the largest of steam locomotives.

For some interesting reading check out the PRR Test Plant Data. They were getting 65,000 lbs/hour out of a 4-6-2 in 1915.

http://books.google.com/books?id=ZiryAA ... &q&f=false

My bad. I was thinking from the heat transfer side, not the mass balance side.
I was always trying to get as many BTU'S across the tube wall as possible and the mass flow rate didn't change.

That's what the theory says....I've never been able to get the steam to sit on the scale long enough to get a good reading. It either runs off because it's embarrassed to let people see how much it gained since High School, or it condenses and then, well, it isn't steam any more so why bother?

dave

Actually, Dave, if you want to split angstroms, in a boiling water nuclear reactor where there are free neutrons, they will hit the water molecules and some neutrons will be absorbed by the hydrogen creating deuterium or tritium. Thus the pound of steam coming out of the top WILL weigh more than the pound of water that went into the bottom (for the same number of water molecules). A(lways)S(ometimes)M(aybe)E(xcept).

I'm going to side with Tom on this one. I worked in the steam industry for 28.5 years and that's the way I learned it.

Some of the plants that I worked in were comparativley small, had one dearator and around 680,000 lbs./hr capacity, then a large Power Plant which regularly ran at 1,060,000 lbs./hr. It was fed from two ends with feedpumps, a dearator and direct contact heater on each end. The last place that I worked before retirement was a modern Cogen facility with a pair of units that were independent of each other. We found out that in times of upset where the 830 lb. header was low, you could really push these things and safely exceed flow limits.

You can get too wrapped up in book answers sometimes. "A pound of water equals a pound of steam" Never mind the fuel consumed. This is a feedwater relationship.

As far as locomotives, I have seen the ratings that are being discussed in some papers, especially those with larger boilers. You just have to look a little, but I'd guess and say that around 100,000 lbs./hr. might be reasonable.

Martyn,

The N&W Class J 4-8-4 produced total evaporation figures of 99,900 to 104,000 lbs of steam per hr. This is total evaporation, which is water from thr tender plus condensate from the feedwater heater. These were achieved under constant speed conditions while trying to measure the economies of raising the boiler pressure from 275 psi to 300 psi. As a result, they are not "maximum" figures in the usual sense of the word. The figures were not limited by grate, evaporation or drafting restrictions. They can be considered relatively conservative readings for the locomotive.

The PRR T1 also produced about 105,000 lbs/hr total evaporation on the Altoona test plant. However, this was under high output testing and both the unit evaporation rate and the firing rate were high. Complete documentation exists for all of the Altoona tests. Actual over-the-road test figures were lower than this, usually in the 85,000 lbs/hr range.

The figure you mentioned for the Q2 is also total evaporation.

The unit evaporation rate of 55 lbs per SF of DHS mentioned earlier is too conservative form modern steam locomotives, at least in the US. Ralph Johnson (Baldwin) suggests a figure of 80 lbs/SF DHS is more reasonable, with higher figures under short term test or maximum performance situations.

Any large US 4-8-4 (ATSF 3776, ATSF 2900, NYC S1b, C&O J3a) can likely produce 100,000 lbs of steam per hour under certain conditions, but the N&W J figures are only ones I have from actual tests where complete documentation exists.