Effect of HIPPs with PRV as Overpressure Protection

[asade]

What effects would HIPPS (High Integrity Pressure Protection Systems) have when it is used along with PRV on compressor discharge line to prevent the system from overpressure due to block discharge outlet?

I understand that HIPPs cannot replace the action of a PRV, but it can reduce the relief load expected from the system. If this is achievable, what fration of the load would PRV relief?

I would appreciate input and queries.

Regards

 

[ajs1972]

The HIPPS and PRV are two independents layers of protection. Must be placed according to a hazard review of the process. The HIPPS not reduces the relief load but the total relief; in case of the HIPPS fails, the PRV must be activated in order to avoid the overpressure of the system.

For example, if your systems supports 200 bar, the HIPPS will act at 180 bar closing the valve or valves of HIPPS system. If the HIPPS fails, the PRV will act in 190 bar.

 

[asade]

The system in consideration is the discharge outlet of a high pressure compressor dealing with high gas flow rate through it.

I understand that the total gas flow should be relieved in case of blocked outlet which can cause system overpressure. The discharge line would be protected with blowdown valve, anti-surge valve and PRV.

I understand that incase of overpressure, we can not rely on process controls and instrumentation. BDV is initiated, but the PRV operates automatically.

If the PRV relieves, its total relief load is equivalent to the total gas flow through the system resulting in designing for a flare system that would handle the flow rate, which affects the size of the Flare KO drum and flare system.

This is the reason why i was asking for opinion on how to minimize the effect of the load on the flare KO drum and system. Gas flow rate through the compressor is 1,617,228 kg/hr.

 

[Buchi]

Hi,

The HIPPS according to ASME case 2211 can replace a PRV. This is a case where an instrumented system can be used to replace a PRV.

So, HIPPs when used, are proactive and can eliminate a particular relieving load scenario which could have been handled by a PRV. it cuts of the source of overpressure,which is the real benefit of resorting to HIPPs. so, if you have used HIPPs, which has to be justified, you should not be worrying about the relieving load in the equipment you have used HIPPs

Buchi

 

[dcasto]

If you can afford to run 50,000HP compressors and 1.7BCFD of gas, surely the safety of that equipment is worth a slightly larger KO drum.