Ethylene reactor

This technology led to testing of a full scale, 100 million lb-per-year ethylene reactor. The full-scale tests have verified scale criteria and gas yield cracking patterns. To further minimize the technical risk and complete the development effort, Union Carbide is constructing a 15 MM ACR prototype unit at Seadrift, TX, primarily to prove long-term equipment operability. This demonstration unit will be completed in 1979 and can lead to the construction of a world-scale ethylene unit by the mid-1980s. 

Tarafder, A., Lee, B., Ray, A. K. and Rangaiah, G. P. (2005a). Multi-objective optimization of an industrial ethylene reactor using a Non-dominated sorting genetic algorithm. Industrial and Engineering Chemistry Research, 44, pp. 124-141. 

The assumed running time of both the ethanol and the ethanol dehydration plants is 8500h/year. 73% of the total heat used in the ethanol dehydration process is consumed by the ethylene reactors which are by far the most energy-intensive part of the process. The reactors operate at high temperature (390-450 C) and therefore have to be heated by direct... 

Direct steam injection in the pretreatment steps in ethanol production process (51.2MW) and direct steam to the ethylene reactor (25.1 MW) is not included in the heat integration analysis. This is due to the fact that this steam usage is a process requirement and cannot be replaced by heat exchange with other process streams. These amounts of steam must be added to cover the total steam demand of the processes. 

Figure 4.8 CCC of the ethanol dehydration process direct steam injection of 25 MW steam to the ethylene reactor is considered a process requirement and therefore not included...

Ethanol can be dehvered in gaseous phase to the ethylene reactors in the combined process. Thereby, the cooling demand in the rectifier column is decreased by approximately 14.3 MW, while the demand for preheating the ethanol feed to the dehydration reactor (approx. 4.3 MW) is eliminated, and the heating demand in the furnace of the ethylene plant is decreased by approximately 8.7 MW. Detailed stream data of the combined process is given in Table 4.A.3. 

In order to illustrate heat integration opportunities and thus also to estimate the utility savings potential, a background/foreground (BF) analysis of the two processes was performed. Figure 4.9 shows the BF analysis of the combined processes. It can be seen that there is an opportunity to recover 44.5 MW of excess heat in the ethanol dehydration process and deliver it to the ethanol production process. As mentioned previously, most of the excess heat at higher temperatures originates from the ethylene reactor effluent. The hot ethylene reactor effluent stream is cooled from 428 to 84 C and has a relatively... 

The secondary reactions are parallel with respect to ethylene oxide but series with respect to monoethanolamine. Monoethanolamine is more valuable than both the di- and triethanolamine. As a first step in the flowsheet synthesis, make an initial choice of reactor which will maximize the production of monoethanolamine relative to di- and triethanolamine. 

An excess of ammonia in the reactor decreases the concentrations of monoetha-nolamine, diethanolamine, and ethylene oxide and decreases the rates of reaction for both secondary reactions. 

Can the useful material lost in the purge streams be reduced by additional reaction If the purge stream contains significant quantities of reactants, then placing a reactor and additional separation on the purge can sometimes be justified. This technique is used in some designs of ethylene oxide processes. 

This problem is solved in the reactor shown in Fig. 10.6. Ethylene and chlorine are introduced into circulating liquid dichloroethane. They dissolve and react to form more dichloroethane. No boiling takes place in the zone where the reactants are introduced or in the zone of reaction. As shown in Fig. 10.6, the reactor has a U-leg in which dichloroethane circulates as a result of gas lift and thermosyphon effects. Ethylene and chlorine are introduced at the bottom of the up-leg, which is under sufficient hydrostatic head to prevent boiling. 

The desired form in homopolymers is the isotactic arrangement (at least 93% is required to give the desired properties). Copolymers have a random arrangement. In block copolymers a secondary reactor is used where active polymer chains can further polymerize to produce segments that use ethylene monomer. 

Methane has also been used in aerobic bioreactors that are part of a pump-and-treat operation, and toluene and phenol have also been used as co-substrates at the pilot scale (29). Anaerobic reactors have also been developed for treating trichloroethylene. Eor example, Wu and co-workers (30) have developed a successful upflow anaerobic methanogenic bioreactor that converts trichloroethylene and several other halogenated compounds to ethylene. 

In the one-stage process (Fig. 2), ethylene, oxygen, and recycle gas are directed to a vertical reactor for contact with the catalyst solution under slight pressure. The water evaporated during the reaction absorbs the heat evolved, and make-up water is fed as necessary to maintain the desired catalyst concentration. The gases are water-scmbbed and the resulting acetaldehyde solution is fed to a distUlation column. The tad-gas from the scmbber is recycled to the reactor. Inert materials are eliminated from the recycle gas in a bleed-stream which flows to an auxdiary reactor for additional ethylene conversion. 

From Acetylene. Although acetaldehyde has been produced commercially by the hydration of acetylene since 1916, this procedure has been almost completely replaced by the direct oxidation of ethylene. In the hydration process, high purity acetylene under a pressure of 103.4 kPa (15 psi) is passed into a vertical reactor containing a mercury catalyst dissolved in 18—25% sulfuric acid at 70—90°C (see Acetylene-DERIVED chemicals). 

The process can be operated in two modes co-fed and redox. The co-fed mode employs addition of O2 to the methane/natural gas feed and subsequent conversion over a metal oxide catalyst. The redox mode requires the oxidant to be from the lattice oxygen of a reducible metal oxide in the reactor bed. After methane oxidation has consumed nearly all the lattice oxygen, the reduced metal oxide is reoxidized using an air stream. Both methods have processing advantages and disadvantages. In all cases, however, the process is mn to maximize production of the more desired ethylene product. 

There have been many variations in the design of electric arc reactors but only three have been commercialized. The most important is the installation at Hbls. The other commercial arc processes were those of Du Pont (3) (a high speed rotating arc) and a Romanian process that produced both ethylene and acetylene. The Hbls process and the Romanian process (at Borzesti, Romania) are still operating, but the Du Pont process has been shut down since 1969. 

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