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[Jome128]

Dear Eng-tips members:

I plan to design an biogas flare system, which is the anaerobic reactor producing a amount of methane gas (biogas) (about 2000m3/hr). The biogas will be discharge through the blower to the flare system, or the steam boiler system. In normal operation, the biogas to be discharge to the steam boiler system when the blower’s discharge pressure is greater than the steam boiler's back pressure 0.51kg/cm2g.
In the upset operating case, ex. the abnormal shutdown of steam boiler, the upstream pressure to be buildup and is greater than the downstream design pressure (0.63kg/cm2g) of the blower.
(Please see the attached drawing of this flare system)

The following is the operating design condition of this system :
As the PT4 to be detected > 0.63kg/cm2g, biogas will be discharged to the flare system.
As system pressure > PT-3 set pressure = 0.3 kg/cm2g, the Blower 2 to be activate to run.
As system pressure > PT-3 set pressure = 0.35kg/cm2g, SOV-5 to be activated to open and pilot gas to be turn on the fire.

If PCV-1’s opening percentage > 80%, and the PIC-3 >0.4kg/cm2g, then the PCV-2 & Louver HOA-8 be open.
If PCV-1’s opening percentage < 20%, then PCV-2 & Louver HOA-8 to be shutdown.
As system pressure < PT-3 set pressure = 0.1kg/cm2g, PCV1 & Louver HOA-8 to be shutdown.

Please help me to confirm the following simple question :

1. Is the PCV4 & PT4 set pressure (0.63kg/cm2g) is reasonable, and this flare system can work normal if the PCV to be take out?
2. Is the PCV1&PCV2 a control valve or a on-off valve (split range control)?

Thank you very much for all your time and help.

Attached Files

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