Protein supplement production process control – Part 2
Thursday, March 8th, 2012 5:49:30 by Ahmed Tariq
Protein supplement production process control – Part 2
Pressure Control
Due to high flow rates of hot air and the operation of direct fired heater in the process, there is a significant danger of over pressurizing the system. Therefore Safety Equipment is needed to be in place to reduce this hazard.
Air Fans F002 and F001 are used to move the air though the system. Significant pressure drops can occur at the bottom of the chamber and also in the downstream cyclone/scrubber system (Perry, 1997). The air fans installed can provide sufficient
pressure to overcome these pressure losses and maintain the system to just above atmospheric pressure.
Pressure alarm high (PAH8) is placed to alert the controller in control room of any significant pressure changes, which can be caused due to mal operation of control valves or extra heating of the air. The alarm will sound if
the set pressure changes to 20% of the set value. This system would enable the operator to check all the parameters of the process are set correctly and make any changes to the heating input before the plant had to be shutdown.
In case of over pressure of the air line, the relief vale SR016
will lift to relieve any over pressure. This relief valve will be thermally sized such as to relieve any pressure that can be caused by thermal expansion of the air in the line. There is also a separate pressure relieve system on dryer. The relief
pressure set on this system is just below the maximum attainable pressure of the dryer. The bursting disc SR015
will have a tail back on it to trip complete process unit. This bursting disc relief pressure will be set at higher temperature to that of Pressure relief valve. This bursting disc will only bust in case the pressure relieving valve fails to relief
the pressure quickly and the back the pressure builds up
The response of the bursting discs is much quicker to that of relief valves and it can relieve high volumes at much quicker rate with little pressure drop. However the bursting discs has to be replaced quite often and a complete
shutdown of plant is required to carry out this job (Perry, 1997).
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Posted by Ahmed Tariq
on Mar 8 2012. Filed under Sci-Tech.
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