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In our Diesel hydrotreater unit we faced an issue in heater steam coils.The steam outlet temperature was 230 before desuperheating and after desupheater more than 380 deg C . We injected boiler feed water to desuperheater to reduce the temperature but we absorbed temperature goes up even we closed boiler feed water.we checked all instruments it's good. What is the problem behind that and how to solve it?
 
Answers
11/09/2017 A: Abhay Raj Mishra, Iocl, mishraar@indianoil.in
if your instrument is correct, then there is a chance that the steam coil is dry and when you inject BFW for desuperheating, then BFW water get evaporated and super heated.
The other possibility is the pressure imbalance, when you inject BFW, simultaneously pressure increases and which allow the steam to flow through coil.
Better you continue BFW and observe at least half an hour, if temperature rise stops or started reducing then the problem is of low flow.
you can check coil outlet temperature by taking line skin temperature before and after the desuper heater.
31/08/2017 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
If your instruments are not in error, then it sounds like you have superheated steam instead of BFW coming into the desuperheater. The fact that blocking in the BFW does not change anything, makes it sound like there is some other connection into the system that is providing an alternative route for the SH steam to get in. If the pressure on this SH steam source is higher than the BFW it would also back out BFW flow, thus preventing it from doing its job.