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| Boiler Warm Up Time https://www.rypn.org/forums/viewtopic.php?f=1&t=34066 |
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| Author: | Jim Baker [ Sat Nov 03, 2012 1:30 pm ] |
| Post subject: | Boiler Warm Up Time |
How long should it take to heat up a boiler from cold, say 50 degrees, to 200 psi? I'm thinking of a 10-wheeler that weighs around 100 tons. Boiler drum is about 6 ft diameter, with tubes 15 ft long. Oil burner, with a crown bar firebox. I'm sure, the longer, the better. But what is reasonable, and how would that compare to general practice with railroads in the 1930's? thanks. |
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| Author: | Dave [ Sat Nov 03, 2012 2:28 pm ] |
| Post subject: | Re: Boiler Warm Up Time |
It's a fairly small locomotive. I'd think in the 7-8 hour range would be reasonable, with about 70% of the time being just getting everything eased up to 212 to start the boil. Once there's 15-20 PSI on the gage, you can light up on steam and increase the heat more rapidly than before. If you have the luxury of warming up the previous day to not quite boiling and then start from warm the next day, maybe 3-4 hours from warm to steam. I'd recommend that process - no calendar day lost with no PSI on the gage even if there's a fire in the firebox, and it eases the reaction to expansion stresses considerably. dave |
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| Author: | Bobk [ Sat Nov 03, 2012 8:16 pm ] |
| Post subject: | Re: Boiler Warm Up Time |
Jim, If you can move the water around during heat up then all the better for the boiler. This allows the water to heat evenly without cold spots. Even heating allows even movement in the sheets and tubes. With the circulation you can also push the heat up cycle a bit however the longer the better. Attach a pump to a blowdown line to draw the boiler water from and the other end from the pump through the boiler feed line, injector or feedwater line. This will circulate the water from the lower part of the boiler up to a higher part. The colder water likes to accumulate towards the back and low spots. Moving the wather with a circulating pump helps even heating. |
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| Author: | Kelly Anderson [ Sun Nov 04, 2012 9:30 am ] |
| Post subject: | Re: Boiler Warm Up Time |
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| Author: | Frisco1522 [ Sun Nov 04, 2012 10:07 am ] |
| Post subject: | Re: Boiler Warm Up Time |
Kelly nailed it! We used to take at least 8 hours to bring 1522 from a cold state to operating pressure. You'd be amazed at the pops, noises and jumping the boiler does as it grows. I can't imagine forcing one. I wish I could remember who told me of one where they would fire up, do switching, etc, and shut down within 8 hours. Talk about torturing a boiler. |
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| Author: | J.David [ Sun Nov 04, 2012 10:45 am ] |
| Post subject: | Re: Boiler Warm Up Time |
Greetings: At Valley Railroad, we usually allow 18 to 24 hours. In many respects, coal firing is easier on boiler and fireboxes. Firing up, for example can be accomplished by building a fire, then banking it, allowing the pressure to build up slowly overnight. In the steam era, most roundhouses and engine terminals had stationary boilers had overhead steam lines. When attached to the locomotive's house valve and turned on, cold water in the boiler would be heated and the boiler charged with steam over a period of time. Of course, this process could be speeded up if the locomotive were needed in a hurry... In general, since one of the biggest factors in firebox life per se is expansion and contraction, slower is better. J.David PS: A boiler "popping and jumping" during fire up could mean worn or stuck furnace bearers (if the sliding type). JDC |
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| Author: | Dave Crosby [ Sun Nov 04, 2012 11:32 am ] |
| Post subject: | Re: Boiler Warm Up Time |
This was one of the (several) issues that sidelined the PRR 1361. As I understand it, the K4 was steamed up in the museum yard so that it could "whistle off" for a diesel powered special excursion that ran to Altoona. Fire up time was less than four hours. |
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| Author: | msm57095 [ Sun Nov 04, 2012 8:03 pm ] |
| Post subject: | Re: Boiler Warm Up Time |
Steam up time for the New Hope Valley 17, a 42 ton 0-4-0T, 190PSI MAWP, is 6 hours from ambient. Haven't had a broken stay in 3 years. Never experienced a flue leak in this 15 year maintenance cycle. Mike MacLean Foreman, Steam Operations New Hope Valley Railway http://www.triangletrain.com |
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| Author: | J.David [ Sun Nov 04, 2012 9:20 pm ] |
| Post subject: | Re: Boiler Warm Up Time |
Greetings: One thing to be mindful of is that damage to staybolts, etc. is not noticeable after one or several incidence of quick fire ups or general poor handling. It is the cumulative effect after years of abuse. In a way, it is a pity that steam locomotives are so durable and forgiving. Were it not so, many lessons would have been well learned long ago... J.David |
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| Author: | omar [ Sun Nov 04, 2012 11:28 pm ] |
| Post subject: | Re: Boiler Warm Up Time |
In my old firing daze (pre-JDC) at the Valley RR the standard was 1 lb/minute psi with the boiler already registering on the steam gauge. The lowest pressure was 30psi on #40 due to a relatively leaking throttle valve. We took over 2 hours to bring the pressure up. Unfortunately, that day was a day from hell since the Alemite gun was toast (fersniked) & needed 2 pinch bars & people to hold it down to get enough grease in the bearings. |
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| Author: | Jim Baker [ Mon Nov 05, 2012 10:28 pm ] |
| Post subject: | Re: Boiler Warm Up Time |
Gentlemen: Thanks so much for your information. It will be quite helpful. |
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| Author: | tomgears [ Tue Nov 06, 2012 12:39 am ] |
| Post subject: | Re: Boiler Warm Up Time |
One of the questions on my boiler operator final exam is: Which causes greater stress in a boiler, pressure or temperature? Explain why? |
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| Author: | Jim Baker [ Tue Nov 06, 2012 1:00 am ] |
| Post subject: | Re: Boiler Warm Up Time |
In my not so experienced opinion, I'd say temperature, or more specifically, changes in temperature. I would figure that pressure changes under constant temperature would cause very little dimensional change in the boiler. Like if you pumped compressed air into a boiler and raised the pressure to 200 or so psi. Or during a hydro test where the water pressure is increased, without the temperature increasing. But, temperature changes, especially when going from a cold boiler to full steam pressure, cause significant dimensional changes. Ever the temperature changes that happen when a fireman has trouble in maintaining a constant pressure are enough to cause leaks at the tube/tube sheet joint. Uneven expansion/contraction, I would think can cause significant stresses. |
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| Author: | sbhunterca [ Tue Nov 06, 2012 9:23 am ] |
| Post subject: | Re: Boiler Warm Up Time |
Quote: One of the questions on my boiler operator final exam is: Which causes greater stress in a boiler, pressure or temperature? Explain why? An important point is that when a boiler is being heated by the fire, the expansion is concentrated around the firebox until the boiler is fully under steam. Increasing pressure in a boiler, without changing the temperature, does not cause the stress to be concentrated in the same way. As mentioned previously, the heating/ cooling cycles in an oil burner are generally much more severe than in a coal or wood burner, since there is a minimum heat that can be produced. You can't build a small fire in the middle of the grates to gradually warm things up with an oil burner! Warming a boiler with shop steam before lighting a fire can pretty much eliminate the uneven expansion around the firebox and tube sheets. Steve Hunter |
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| Author: | Sully [ Tue Nov 06, 2012 11:06 am ] |
| Post subject: | Re: Boiler Warm Up Time |
Quote: You can't build a small fire in the middle of the grates to gradually warm things up with an oil burner! I respectfully request that you reconsider that statement. I cannot argue the finer points of a coal fire - but I CAN build a small fire in an oil burner - with several methods; 1)you can use a solid fuel to start/warm the firebox and firebricks 2)you can use a pilot fire to have a small liquid fuel fire again to slowly warm the firebox and firebrick 3) if the fuel lever/burner allows you can start a 'small' fire. I have seen a fire in an oil burner fire that would never boil water. Also, don't forget the firebrick acts as both an insulator and a conductor as it carries heat and it has some thermal mass. I don't mean to pick on anyone nor do I mean any disrespect, but am a lurker here and several times I have seen comments about oil burning that sounds like it is on or off - oil is all about btu/gal - so there is a big difference in a 1" oil valve at idle with a tad more than a drip, and at 3/4 open. Any GrandCanyon, BlackHills, or other folks want to comment or add their experiences? Nigel? |
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