Vacuum flooding

gcp13

Today I found a commercial steam boiler(2 pipe) for steam kettles flooded. After cleaning the sight glass and controls I started running cycles.
The boiler ran fine cycling on pressure then after it started to cool I found that a vacuum was created and was pulling feed water from feed tank without pump running. I tested a few times same thing unless I pulled plug to break vacuum. Anyonehavethis problem? I ended up putting a Hoffman 62 vacuum breaker on boiler. But why now what could have changed?

Jamie Hall

What was venting the system before? Anything? It might have gotten stuck shut.

gcp13

Piped up to Solinoid valves into kettles then out to y strainer,high pressure steam traps then back down into condensate feed tank that was vented off the top.
Could the steam traps close and not open back up due to high pressure?

gcp13

System running better with vacuum breakers installed. water is not syphoning back to boiler anymore.

Dave in QCA

As you describe the system, of course the kettle will not see vacuum because as steam is shut off because the exiting trap or orifice is still open to the vented condensate receiver. I would have thought that the steam piping between the boiler and the kettle would have had a trapped drip leg somewhere that might have drained to the condensate receiver. If it were there, it would relieve the vacuum. I cannot explain why the problem suddenly appeared. Maybe they seldom shut down the boiler? Maybe they were used to a whole lot of banging and whooshing when they started it up. Its possible that it has been starting up flooded for a long time. When operating staff doesn't understand how something is supposed to properly operate, they will except improper operation as normal.

By the way.... a steam kettle is an amazing thing. I remember testing out a newly installed kettle to see how it would work. Ran a few inches of cold water in the bottom and turned on the steam. Within a minutes it was boiling! A capacity to heat VERY fast, but never scorch or burn. Amazing!

On that subject, back in 1914, our Louis P. Best, builder of our Grandview mansion in Davenport, built a large sorghum molasses refinery in Ft. Smith, Arkansas, in fact, it was the largest sorghum molasses plant in the world. They had a huge boiler capacity to cook the sorghum. But, the problem with sorghum is that it will actually scorch at 212F, so the plant included some huge vacuum pumps, to run the steam at a lower temperature and cook the molasses at the proper low temperature, but with the incredible speed of a steam kettle.

gcp13

Thanks for the info.im heading back soon I'll try to find any drip or trapped return that maybe clogged.this is two kettles for brewing beer, they run on 9 psi and run 1 kettle daily and the 2nd one once or twice a week. they couldn't even see the water level to check it,could have been running flooded for a long time.

Dave in QCA

Sounds like it's been a problem and they didn't know it. Breaker will correct it.

gcp13

Thanks again