Wood Drying Topics > Dry Kiln Maintenance

kiln coils & steam traps

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wayne cunliff:
Want to know what type of test you do to test or check them and if any of you use enercon orifice steam traps.  I run a Cleaver Brooks low pressure 15psi boiler feeding two double track kilns ones 65 feet the other is 90 feet, i have been doing checks with a heat gun and im finding dead spots in my coils like 200 degree's on say the top three and bottom and in the middle it would be 80 degree's. There horizontall standing coil's 21' long ten of them in a section three sections high make a zone.  We thought they were old and bad since they have been in there since 1961 so we bought a new one put it in and cut the ends off the old one and it is spot less on the end side.

MichaelM:
The most reliable way to check a trap is with test valves before and after the trap.  Having said that, the coils are not draining if they are cold at the bottom because steam will have a constant temperature through the coil.  The coils might back up some at start up, so I would test at other times during the schedule - the middle and end.  In the middle of the schedule the control valve is probably mostly open and there is probably enough pressure in the coil to cause it to drain. At the end, when the heat demand is low, the pressure in the coil is less and may not be greater than the pressure on the discharge side of the trap.  Contributing factors are small or long return lines, elevated condensate tanks, and backpressure from other kilns draining into the line or a failed-open trap blowing steam.
I can't really say more without knowing more about the problem and the system.

I hope some folks will comment on their experiences with orafice traps in kilns.

Joe D:
Another way to test is using a heat gun. With the orifice type traps you will need to develop your information on the temperature differential you should see from the inlet side of the trap to the exiting side.

Michael had some good thoughts on what to look for as far as why your not seeing one area of a set of coils heating. Also each set of coils should be trapped (I could not tell this by what you wrote) because with more than one col feeding into a trap you can get some pressure build up that prevents draining of a coil. With older kilns insure your coils are sloped (check the coil hangers, etc) so the coils can drain.

Last of all make sure you have a trap that can handle the job you want it to do in terms of condensate load, pressures and consistency of load and pressures.

wayne cunliff:
all of the coil sections have there own traps and it's not the bottom or tops of the coil its the middle its random some coil sections the whole thing is say 220 and some its 3 or 4 in the middle that are say 80 deg iv heard it called short circuit of coils. I have tested them at 25% 50% and 100% with the same out come the grade is good and no bellys. Im currently looking for a steam  specialist that dont mind driveing to riddle to better evaluate are system, if any of you no of any one shoot me a email at kiln@cdlumber.com or just post on here thank you

Joe D:
Wayne, a good source of a steam specialist may be you trap supplier. They may have one on staff. If not, their competition will. You may have an airlock going on.

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