Petrochemical industry distillation systems

The candidate technologies for purification are many. Distillation, the work-horse of the chemical processes, leads the pack. Most of the synthesis effort to date has concentrated on the product purification step. This step is often the last step for liquid products especially in the chemical and petrochemical industries. The biochemical industry utilizes membrane and chromatographic processes more than the other industries due to the thermal stability and purity requirements. In the electronic industry, membrane processes are more prevalent due the ultra-purities necessary. Supercritical fractionation of alcohol water systems with the aid of a dense gas is an example of a purification step. 

In the laboratory, styrene can be prepared by the decarboxylation of cinnamic acid, as shown in Reaction 1, using dry distillation. However, styrene is produced commercially from ethylene and benzene, two basic ingiedienis of the petrochemical industry. With electrophilic addition of ethylene to benzene, a mixture of ethyl benzene and diethylbenzene is obtained as own in Reaction 2. The dehydrogenation of these benzene derivatives produces slyrene and divinylbenzene, respectively (Reaction 3). A detailed synthesis of styrene is described by Berthelot et al (6). As mentioned earlier, styrene is an important monomer in many industrial polymers. Additionally, divinylbenzene which is produced as a by-product is an effective crosslinker for ion-exchange resins, polystyrene-based supported reagents and catalysts, and low profile additive in a number of liquid molding resin systems. 

Another flowsheet is in Fig. 2-4. The distillation column is complemented by two heat exchangers which makes possible preheating of the feed by the contact with hot bottom product. In practice, especially in refinery and petrochemical industries, we can meet even with much complicated heat exchange systems consisting of dozens of heat exchangers which make processes economically viable. 

Two options are being developed at the moment. The first is to produce 1,2-propanediol (propylene glycol) from glycerol. 1,2-Propanediol has a number of industrial uses, including as a less toxic alternative to ethylene glycol in anti-freeze. Conventionally, 1,2-propanediol is made from a petrochemical feedstock, propylene oxide. The new process uses a combination of a copper-chromite catalyst and reactive distillation. The catalyst operates at a lower temperature and pressure than alternative systems 220°C compared to 260°C and 10 bar compared to 150 bar. The process also produces fewer by-products, and should be cheaper than petrochemical routes at current prices for natural glycerol. The first commercial plant is under construction and the process is being actively licensed to other companies. 

Columns and towers are the most essential aspects of the refinery system in the petrochemical or in the process chemical industries. They are divided into three separate functions distillation, fractionation, and chemical operations. Stills are cylindrical chambers in which the application of heat to the charge stock changes from a liquid to a vapor. The vapor is then condensed in another vessel. Columns and towers are stills that increase the degree of separation that can be obtained during the distillation of crude oil. Fractionation towers are used for light end products. Generally, towers are large cylindrical vessels that have plates... 

Industrial processes are categorized as petrochemical, refinery, environmental, or gas processes. There are hundreds of different processes, and the overall total has been expanded significantly by the petrochemical and environmental. The more common petrochemical processes use ethylene, olefins, benzene, ammonia, and aromatics. Refinery operations include traditional crude distillation, reforming, cracking, isomerization coking, and alkylation. Environmental systems are applied to water treatment, air pollution, solid waste, and toxic waste. 

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