Plug-flow reactors ethylene production

Davis et al. [9] have performed studies on the batch hydration of ethylene oxide. Their work determined the value of the product distribution constant K. This value is used in Equation 5-378 to determine the expected performance in a plug flow reactor. This value is also used in Equation 5-394 to illustrate the poor performance that would be obtained with complete backmixing. 

Figure 4.10 Typical results of the calculations of expected variations in the stationary concentrations of components at the benzene (B) alkylation with ethylene (E) along a plug-flow reactor of length L at 210 C x is the distance from the inlet of the reactor. The calculations were performed in terms of the Horiuti-Boreskov-Onsager reciprocity relations to optimize the composition of the initial reaction mixture so the outlet and inlet diethylbenzene (DBE) concentrations would be identical, which means 100% selectivity of the process in respect to the target product ethylbenzene (EB).

Figure 4.10 illustrates the results of typical calculations of the reaction mixture composition evolution in the plug flow reactor the calculations are made using the preceding relationships, the relevant mass balance equa tions, and literature data on Kpi at 210° C. The evolution in time of the ini tial product concentrations including DEB is seen to lead eventually to the situation when the inlet and outlet DEB concentrations become equal. This means that the proper choice of the composition of the initial reaction mix ture makes the process 100% selective in respect to the conversion of the initial reactants, benzene and ethylene, to EB (see Figure 4.10) even though no transalkylation reactor is used. 

Tubular and columnar apparatus (apparatus length-to-diameter ratio L/d > 100) including screw equipment relate to plug-flow reactors type [7,8]. Plug-flow reactors are applied for many of gas-phase reactions realized in production quantities, in particular for ethylene polymerization under high pressure conditions [9], and for some liquid-phase reactions, for example polystyrene synthesis in columns and other rubbers and plastics productions. Near 10% of polymer and 30% of fibers manufacture are produced in apparatus of such types [10]. 

There are different tubular and column plug flow reactors as well as screw reactors [1]. Plug flow reactors are used for various gas-phase reactions occuring within industrial-scale production, particularly for the reactions of nitrogen oxide oxidation, ethylene chloration, and high-pressure ethylene polymerisation. They are also used for some liquid-phase and gas-liquid reactions, e.g., styrene polymer production in a column, plastic and rubber production, synthesis of ammonia and methanol, and sulfation of olefins [2]. 

Particles of polypropylene are continuously formed at low pressure in the reactor (1) in the presence of catalyst. Evaporated monomer is partially condensed and recycled. The liquid monomer with fresh propylene is sprayed onto the stirred powder bed to provide evaporative cooling. The powder is passed through a gas-lock system (2) to a second reactor (3). This acts in a similar manner to the first, except that ethylene as well as propylene is fed to the system for impact co-polymer production. The horizontal reactor makes the powder residence time distribution approach that of plug-flow. The stirred bed is well suited to handling some high ethylene co-polymers that may not flow or fluidize well. 

Triethanolamine is produced from ethylene oxide and ammonia at 5 atm total pressure via three consecutive elementary chemical reactions in a gas-phase plug-flow tubular reactor (PFR) that is not insulated from the surroundings. Ethylene oxide must react with the products from the first and second reactions before triethanolamine is formed in the third elementary step. The reaction scheme is described below via equations (1-1) to (1-3). All reactions are elementary, irreversible, and occur in the gas phase. In the first reaction, ethylene oxide, which is a cyclic ether, and ammonia combine to form monoethanolamine ... 

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