5 replies to this topic

[krishna unni]

we have an ethylene compressor, which is recycling around 3 MT/hr gas having pressure 250 bar and 70 degree c. I would like to throttle it to utilise the cold energy produced. The schematic diagram is attached herewith.

Please let me know whether it is practicable.
The heat duty expected is 310000 k cal/hr

presently the exchanger E-2 is utilising chilled water from VAR. I would like to replace the chilled water by MEG solution as load on VAR is on higher side,

Attached Files

•  scheme1.xls   32KB   34 downloads

[abhi_agrawa]

Krishna,

- At 250 bar pressure and 70^oC temperature Ethylene is in the super-critical state. Have you accounted for this? Critical pressure and temperature of Ethylene is 50.418 bar and 9.20 ^oC (source http://webbook.nist.gov)
- The inlet and outlet temperature of Ethylene compressor as shown by you is 70 ^oC. Is it possible or am I missing something?
- Please remember that as soon as you put some heat load on the recirculating(?) Ethylene, the temperature of the compressor suction will increase. This will increase the volumetric flow to the compressor which may make the compressor inadequate.
- At 15 bar and 30 ^oC, Ethylene is in vapor state. You will be able to extract very little "chillness". Suggest you consider throttling downstream of E-1.

abhishek

[shan]

we have an ethylene compressor, which is recycling around 3 MT/hr gas having pressure 250 bar and 70 degree c. I would like to throttle it to utilise the cold energy produced. The schematic diagram is attached herewith.

Please let me know whether it is practicable.
The heat duty expected is 310000 k cal/hr

presently the exchanger E-2 is utilising chilled water from VAR. I would like to replace the chilled water by MEG solution as load on VAR is on higher side,

Per my Hysys simulation, you can have 129,000 kcal/hr from E-1. How can you satisfy E-2 duty requirement 309,120 kcal/hr?

[krishna unni]

Krishna,

- At 250 bar pressure and 70^oC temperature Ethylene is in the super-critical state. Have you accounted for this? Critical pressure and temperature of Ethylene is 50.418 bar and 9.20 ^oC (source http://webbook.nist.gov)
- The inlet and outlet temperature of Ethylene compressor as shown by you is 70 ^oC. Is it possible or am I missing something?
- Please remember that as soon as you put some heat load on the recirculating(?) Ethylene, the temperature of the compressor suction will increase. This will increase the volumetric flow to the compressor which may make the compressor inadequate.
- At 15 bar and 30 ^oC, Ethylene is in vapor state. You will be able to extract very little "chillness". Suggest you consider throttling downstream of E-1.

abhishek

thank you abhishek. what i have to accout in supercritical state?. In the extent cas it may liquify. but the expansion effect results a huge cold energy i think. There is no requriement of throttling after E-1 because i need the chillness inside the exchanger.If the recycle reduces no issue here as the suction vessel pressure control is not by the recycle.

In our system E-1 outlet at goes to another compressor which delivers1500 bar.

[krishna unni]

we have an ethylene compressor, which is recycling around 3 MT/hr gas having pressure 250 bar and 70 degree c. I would like to throttle it to utilise the cold energy produced. The schematic diagram is attached herewith.

Please let me know whether it is practicable.
The heat duty expected is 310000 k cal/hr

presently the exchanger E-2 is utilising chilled water from VAR. I would like to replace the chilled water by MEG solution as load on VAR is on higher side,

Per my Hysys simulation, you can have 129,000 kcal/hr from E-1. How can you satisfy E-2 duty requirement 309,120 kcal/hr?

thankyou shan,

please let me know what is the temperature and state of the ethylene just after the throttling valve when gas expands from 250 bar 70degree to 20 bar

[shan]

we have an ethylene compressor, which is recycling around 3 MT/hr gas having pressure 250 bar and 70 degree c. I would like to throttle it to utilise the cold energy produced. The schematic diagram is attached herewith.

Please let me know whether it is practicable.
The heat duty expected is 310000 k cal/hr

presently the exchanger E-2 is utilising chilled water from VAR. I would like to replace the chilled water by MEG solution as load on VAR is on higher side,

Per my Hysys simulation, you can have 129,000 kcal/hr from E-1. How can you satisfy E-2 duty requirement 309,120 kcal/hr?

thankyou shan,

please let me know what is the temperature and state of the ethylene just after the throttling valve when gas expands from 250 bar 70degree to 20 bar

Temperature: -28.9C
Vapor Mole Fraction: 0.81