TECHNOVACUUM

Layout of the two-stage VHC unit with steam and liquid circulation loops.

Compression of gas-vapor mixture evacuated from the vacuum column is performed in two stages with intermediate condensation of vapor phase in the vacuum condenser T-1.

At the first stage gas-vapor mixture is compressed due to energy of water condensate steam that is delivered to the steam ejector B-1. Compression at the second stage is made due to energy of hydrocarbon motive liquid that is delivered to the jet device CA-2 by the pump H-2. At both compression stages high pressure motive fluid (ejecting flow) that enters the steam ejector B-1 at the first stage (water condensate steam) and the liquid-gas jet device CA-2 at the second stage (hydrocarbon fraction), circulates along closed loop. Some renewal of circulating motive fluid is provided due to condensation of water vapor that is contained in gas-vapor mixture evacuated from the vacuum column (renewal of circulating motive fluid from external source is possible).

Low pressure steam at pressure 0.3 MPa (abs.) and temperature 130…150°C is produced for the steam ejector B-1 of the first compression stage by the steam generator E-1 from water condensate which is generated in the separator C-1 after separation of vapor phase condensate, delivered from the condenser T-1, into water condensate and hydrocarbon one. Water condensate is transformed into steam due to heat of hot product of crude distillation column or residuum vacuum column. It is reasonable to use distillate streams heat of which is discharged to atmosphere.

At the first compression stage of the proposed vacuum creating unit, water condensate is circulated as follows:

- it is delivered from the separator C-1 to the steam generator E-1 by the pump H-1;
- water condensate steam is fed from the steam generator E-1 to the steam ejector B-1 and compresses gas-vapor mixture from vacuum column pressure up to pressure in the condenser T-1;
- gas-vapor mixture is cooled into the condenser T-1 by circulating water and is separated into vapor phase condensate and gas mixture that is delivered to the liquid-gas jet device CA-2 of the second compression stage;
- vapor phase condensate goes to the separator C-1;
- water condensate is delivered from the separator C-1 to inlet of the pump H-1 and then to the steam generator E-1; hydrocarbon condensate and excess of water condensate are withdrawn from the unit.

Circulation of water condensate and generation of steam due to heat of hot distillate which is transferred from, for example, atmospheric or vacuum distillation columns, exclude vacuum creating unit’s consumption of steam or external water for its generation.

At the second compression stage of the vacuum creating unit, hydrocarbon fraction that is delivered under pressure to the liquid-gas jet device CA-2 circulates along the closed loop due to the circulating pump H-2.

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