Download Compressor Settleout Pressure and Temperature

Mr. Ankur i want to ask you about liquid volume in settle out condition In your calculation sheet i dont see consideration liquid volume in suction drum and air cooled heat exchanger It means that the liquid volume can be neglegted? 

Babar,

The excel workbook is for settle-out pressure and settle-out temperature. Liquid volume is not considered to play any role in determining these two because at the settle-out pressure and temperature conditions condensation or liquid dropout is generally negligible.

Regards,

Ankur

Ankur,

If we are calculating settle out pressure and temperature for refrigeration compressor circuits in an olefin plant (Ethylene and Propylene Compressors),How do we take account of liquid hold ups in suction and accumulators.Will that play any significance in settle out conditions.

Regards,

Bala

Ankur,

 

If we are calculating settle out pressure and temperature for refrigeration compressor circuits in an olefin plant (Ethylene and Propylene Compressors),How do we take account of liquid hold ups in suction and accumulators.Will that play any significance in settle out conditions.

 

Regards,

Bala

Bala,

I have no real life experience of olefin compressors. However, the pressure will remain in equilibrium with any accumulated liquid in the low points at settle-out conditions before it decays with time. Consequently the temperature at all times will correspond to the pressure in the compressor circuit during and after the compressor settles-out. In other words, the temperature will be a function of the vapor pressure in the compressor circuit.

The spreadsheet I have presented provides the instantaneous settle-out conditions of pressure and temperature when the compressor trips or is shutdown. It is very logical, that pressure will decay over a period of time since no real life system can be 100% pressure tight.

Hope this helps.

Regards,

Ankur

With reference to the settle out calculation I have a querry that in hydrotreater units there are generally fixed bed reactors, in that case how do we estimate the volume as it is filled with packing and also some liquid hold up is also be there?

With reference to the settle out calculation I have a querry that in hydrotreater units there are generally fixed bed reactors, in that case how do we estimate the volume as it is filled with packing and also some liquid hold up is also be there?

The spreadsheet is for a compressor and not for a fixed bed reactor. Furthermore, a hydrotreater is a gas phase reactor, no liquid should exist. Gas volume can be calculated using the bulk density of the catalyst.

Dear Yadav,

Fixed bed reators in operate at high temperature and are in gas pahse and gas volume is easly calculated using void fraction formulae as rightly said by Mr. Ankur.

Dear also please check whether hydrotreater reactors are comming inside the compressore spill-back loop.Generally spill-back ijn hydrotreaters is routed to HP or LP vessels collecting reactor effulent and there will alwyas be a check valve after connecting the spill-back line.