Process Description

The purpose of the Simtronics Refrigerant Chiller is to cool down a process stream using liquid refrigerant in a specially designed heat exchanger to handle boiling of the liquid refrigerant by heat absorbed from the process stream. Liquid refrigerants provide chilling capability because they partially vaporize as they are depressured across a control valve. This vaporization (also called flashing) results in a large decrease of the refrigerant’s temperature so it can be used to chill a process stream.

Warm feedgas is brought in from battery limits under flow control by FIC-501. The feedgas is cooled in Chiller E-501 using liquid high pressure refrigerant (propane) from the Refrigerant Accumulator (battery limit). The liquid refrigerant depressures across a control valve prior to entering E-501, resulting in partial vaporization of the liquid and a large decrease of the stream’s temperature. The refrigerant liquid is contained in the shell side of E-501 and vaporizes from the heat picked up from the warmer process gas flowing through E-501. Refrigerant vapor is collected at the top of the shell of E-501 and returned to the Refrigeration Compressor Suction Drum (battery limit) via a control valve regulated by PIC-601.

TIC-502 controls the feedgas outlet temperature from E-501 by adjusting the set point of pressure controller PIC-601. PIC-601 controls the pressure of the vaporized refrigerant in E-501 by adjusting the refrigerant vapor flow back to the Refrigeration Compressor Suction Drum. Changing the pressure of the shell side of E-501 will, in turn, change the temperature at which the liquid refrigerant boils. This temperature change affects the heat transfer rate in E-501. A higher pressure results in a higher boiling temperature which reduces the heat transfer rate. Conversely, a lower pressure results in a lower boiling temperature which increases the heat transfer rate.

The level of refrigerant on shell side of E-501 is controlled by LIC-601 which adjusts the flow of liquid refrigerant to E-501. The liquid refrigerant for E-501 is supplied directly from the Refrigerant Accumulator. The level of refrigerant in E-501 normally submerses all the tubes of the heat exchanger.