I noticed that whenever there is a delay in charging of any sterrilizer, and the start of a new sterilization cycle, the safety valves on the BPR starts to blow-off. The blow-off continues until the new Sterilizer Cycle starts with the opening and regulation of the Inlet Valve on the Sterilizer. In some instances, I noticed the Engine Driver has to open the By-Pass Exhaust Valve to prevent built-up of steam pressure (more than 45 psig) in the BPR that will cause the steam turbine cycle to drop.
My questions are:
1. Is this normal in palm oil mills?
2. Why the continuous discharge from the
safety Valves and no drop in pressure in the
BPR? I noticed when the Safety Valves on
the boilers blow, the pressure in the boiler
drops quickly and the safety valves close immediately after.
3. How can I prevent the accumulation of
pressure in the BPR automatically without
intervention by the Engine Driver?
Hi Wesley,
This is my take on your question.
Steam blowing from the BPR non-stop is a sign that you may be having delays in charging into or discharging from the Sterilizers and that may eventually affect your milling capacity.
The continuous blowing of steam from the BPR which may lead to accumulation of pressure beyond 3 barg is due to the low discharge rate of steam from the safety Valves on the BPR compared with the incoming steam from the Turbine exhaust. This is assuming the Safety Valves are adequately sized.
The discharge rate of the Safety Valves is limited by the length and size of the exhaust piping after the Safety Valves. Just compare the diameter of the pipe from the Turbine exhaust and the diameter of the pipe after the Safety Valve discharge ports in the photo you attached. If the pipes from the Safety Valves discharge port are short, the steam exhausts immediately to atmosphere, you are OK. However, if the discharge pipes are long and with bends, the discharge rate from the Safety Valves is limited by the size of the pipes. You can check this against the flow chart for steam pipes attached here.
So to prevent accumulation of pressure in the BPR, you will need to increase the diameter of the discharge pipe after the Safety Valves.
I hope this will help resolve your problem.