Stage and Continuous Gas-Liquid Separation Processes

Chap. 10 Stage and Continuous Gas-Liquid Separation Processes... 

This part, on applications, covers the following unit operations 8. Evaporation 9. Drying of Process Materials 10. Stage and Continuous Gas-Liquid Separation Processes (humidification, absorption) 11. Vapor-Liquid Separation Processes (distillation) 12. Liquid—Liquid and Fluid-Solid Separation Processes (adsorption, ion exchange, extraction, leaching, crystallization) 13. Membrane Separation Processes (dialysis, gas separation, reverse osmosis, ultrafiltration) 14. Mechanical-Physical Separation Processes (filtration, settling, centrifugal separation, mechanical size reduction). 

Equations 9.109 and 9.110 are valid for a boiling process in a closed system the gaseous phase develops from a liquid with initial concentration Cq, is the mass fraction of developed gas, and K is the mass distribution constant of the component of interest between gas and liquid. Equations 9.111 and 9.112 describe a multistage separation process in which n is the number of separation stages, AFg is the mass fraction of gas separated in each stage, saiAK is the mean mass distribution constant of the process. Equations 9.113 and 9.114 refer to a boiling process in an open system the gas is continuously removed from the system as the process advances. 

The electrolysis is continued until 90% of the liquid has been converted into O2 and H2 most of the residual liquid is then neutralized with CO2, and the water distilled and added to the remaining electrol5fie. This process is repeated to give <99.9% D2O. In the later stages of the separation, the gas evolved at the cathode is burned to yield partially enriched deuterium oxide that can be electrolysed further. Cheap electrical power is, of course, essential for the economic concentration of D2O by this method. 

Type 8. Gas and liquid chromatographs, the most representative examples of this type of analyser, occupy a prominent piace in current analytical instrumentation. Their sampling operation (Injection) is generally manual and column separation can be considered to be the only sample treatment. They carry out detection In a continuous fashion and usually employ an electronic Integrator or a microprocessor to acquire and process data. Their automation, therefore, involves the complete second and third stages, In addition to part of the first. The Instrument s microprocessor can control (a) the chromatographic furnace, which works at a fixed temperature in liquid chromatography and over... 

In the first stage, a Friedel-Crafts reaction is commonly carried out by treating benzene with ethylene in the liquid phase at 90-100°C at slightly above atmospheric pressure. The catalyst is aluminium chloride (with ethyl chloride as catalyst promoter). A molar excess of benzene is used to reduce the formation of polyethylbenzenes the molar ratio of reactants is generally about 1 0.6. The reactants are fed continuously into the bottom of a reactor whilst crude product is removed from near the top. The product is cooled and allowed to separate into two layers the lower layer, which consists of an aluminium chloride-hydrocarbon complex, is removed and returned to the reactor. The remaining ethylbenzene is then separated by distillation from polyethylbenzenes and benzene, which are recycled (since dealkylation also occurs under the reaction conditions). In newer plants, ethylbenzene is produced in a gas phase process. An excess of benzene is treated with ethylene at about 420°C and 1.2-2 MPa (12-20 atmospheres) in the presence of a zeolite catalyst. 

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