How to define a startup sequence and capacity control of 6 recip compressors( 2stages) working in a recycle process ?
The amount of compressors needed is depending of the process flow through a reactor section. About 80% of this flow is feeding the compressor suction via a pressure controlled vessel. The interstage pressure is used to feed a drying proces section. The high pressure is feeding the reactor section on his turn. The suction pressure is controlled with a bypass valve from the interstage pressure.
What we see is that the interstage pressure builds up because of changing over some equipment, taking out exchangers for maintenance work and wrong manipulations. What we see is that just 30% of the time the suction pressure is around his setpoint. We have also seen that the interstage pressure increases +35% at discharge 1ste stage and decrease at suction 2e stage because of manipulations in the process. We have also problems with vibrations in the system. The high pressure is stable at all times.
Does anyone have some experience with the capacity control and startup sequence of such a system ?
Do we need a bypass valve to control the interstage pressure ? Is a stepless capacity contol on each stage a better solution ?