boiler water wall tube leakage
boiler water wall tube leakage
(OP)
We have two 390 t/hr CFBC boilers supplying steam at 130 ksc and 540 deg C.The boiler has four FBHE's.In one unit we are facing repeated problem of water wall tube leakage in FBHE 2(super heater 2B).Tube leakage occured four times around spiess valve area,two times in straight tube.Boroscopic inspection for checking tube choking did not reveal any result earlier. Flushing of the tubes at high pressure did not yield any result either.
But in the latest failure it is found that one tube is in badly choked condition,the chemical analysis of which has shown that the deposit is 98 % ferrous related (oxides of iron).
My questions are : (1)What could be reason for such deposit after two years of operation that too after acid cleaning and passivation?
(2)How tgo ensure other tubes are not effected at present?
(3)what is the corrective action we can take to aviod such tube failure in future?
Thanking you.
But in the latest failure it is found that one tube is in badly choked condition,the chemical analysis of which has shown that the deposit is 98 % ferrous related (oxides of iron).
My questions are : (1)What could be reason for such deposit after two years of operation that too after acid cleaning and passivation?
(2)How tgo ensure other tubes are not effected at present?
(3)what is the corrective action we can take to aviod such tube failure in future?
Thanking you.





RE: boiler water wall tube leakage
RE: boiler water wall tube leakage
Some use to forgett this detail
RE: boiler water wall tube leakage
RE: boiler water wall tube leakage
Are you blowing your boiler down often enough i.e Bottom, Side and TDS?
Is your feed water being oxygenated from some source?
If you have a water preheat system from say, excess flash, whatever, is there cross contamination from the heat exchanger?
RE: boiler water wall tube leakage
max.press. is a 220 bar
a big problem in p.p is tupe rapther
i want know why?
RE: boiler water wall tube leakage
many times, you'll need the assistance of your chemical supplier or lab, the boiler OEM, or metallurgist to help you determine the cause -- or find someone who has dealt with boilers for a period of time and give them sufficient detail (tube samples to analyze / look at)and they might be able to point out the problems...
can not be determined without a lot of information right in front of one...
RE: boiler water wall tube leakage
You have indicated one of the failed tubes had shown signs of "badly choking"- I assume that means pluggage of the tube inlet section with debris. If so, then you need to use a boroscope and investigate all the inlet headers to determine the amount and kind of debris.
RE: boiler water wall tube leakage
[in over 50 years at my former company, we used a metallugist twice and he only confirmed our own analysis]...
RE: boiler water wall tube leakage
RE: boiler water wall tube leakage
What exactly do the failures look like? Do you have any pictures? Are the failures in refractory covered areas? If so, was the refractory worn away before the failure? If not, is there wear from the outside (I know that is a dumb question, because that should be pretty obvious, but...)?
One problem that can occur with a tube rupture in the furnace of a fluidized bed, especially in the area near the "spiess" valve, is that during the cooldown alot of ash can get into the tubes and block that tube or others in the vicinity. Sometimes this blockage is not obvious because the blockage can be washed away when the leak occurs. You should look in the headers for debris (if you haven't already).
If you have anymore information that might help determine what your problem is let me know.
Regards,
Carl Johnk