Gas Only Flow Capacity of a Hydraulic Power Recovery Turbine (HPRT)

[CCNY]

My question is how to calculate the flow rate of gas only blowthrough through a Hydraulic Power Recovery Turbine (HPRT)

The scenario is upon tripping of the unit feed pump say in a hydrotreater, liquid level in the high pressure separator vessel will be lost and high pressure gas will start to blow through from the high pressure separator vessel to the low pressure separator vessel, located down stream of the HPRT. The relief valve protecting the low pressure side will need to then handle the gas blow through flow.

The question is does the HPRT provide any appreciable resistance against the gas flow and if so how is this resistance accounted for? Or is the resistance to gas flow basically set by the level control valve at the HPRT inlet (choke flow through the valve when the pressure ratio of the high pressure to low pressure side is greater about two) with the HPRT itself not providing a rate limiting resistance to the gas flow?

Thanks

 

[BigInch]

I would think that it would be difficult to place confidence in the discharge pressure one would calculate during turbine spin-down.

Why not size the relief valve for full flow at the relief pressure of the Lo Pressure Separator.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek

 

[CCNY]

BigInch

Thanks. The question still remains and that is how to calculate the full gas flow through the turbine?

 

[BigInch]

Not sure. Gas doesn't operate well through a liquid pump, probably much the same for a liquid turbine. I'd tend to look at it using an equaivalent M x V^2. Find the flowrate of gas that would be equivalent to the mass of liquid when rotating at a given speed.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek

 

[BigInch]

BTW V would be tangential velocity.

If not taking off power, resistance is provided by the turbine's friction and by rotating moment of inertia of all rotating components when accelerating.

Independent events are seldomly independent.