Case Study Interception of Chloroethanol in an Ethyl Chloride Process

If arcow b lies completely to the left of arrow a and is less dian c[, MSA b is chosen, because it is theimodynamic y and economically superior to MSA a. Anodier useful observation can be inferred from the relative location of the sources and the MS As. If an MSA lies to the right of a source node, the MSA is not a ctmdiidate for interceplhig tiiis node, because mass exchange is infeasible. 

Once o mal interception tiati es are prescreened fOT each node, one ctm formulate syntitesis task as an optimization [n ogram whose objective is to minimize inh on cost subject to the p -diagram equations and the prescreened interception strategies. The following example illustrates this approach. 

3 Case pi inlereepti0n of Chloroelhanol in im Elliyi Chtorlde Process 

The compositions of CE in the gaseous and liquid effluents of the ethyl chloride reactor are related through an equilibrium distribution coefficient as follows  

Because of the toxicity of CE, the aqueous effluent from the ethyl chloride reactor, Ri, causes significant problems for the bio-treatment facility. The objective of this case study is to optimally intercept CE-laden streams so as to reduce the CE content of Ri to meet the following regulations  

3 Case study Interception of chloroethanol In an ethyl chloride process 

3 Case Study interception of Chloroethanol in an Ethyl Chloride Process 

Ethyl chloride (C2H5CI) can be manufactured by catalytically reacting ethanol and hydrochloric acid (El-Halwagi et al., 1996). Figiu 7.7 is a simplified flowsheet of 

While ethyl chloride is one of the least toxic of all chlorinated hydrocarbons, CE is a toxic pollutant. The off-gas from the reactor is scrubbed with water in two absoiption columns. The first column is intended to recover the majority of unreacted ethanol, hydrogen chloride, and CE. The second scrubber purifies the product fiom traces of unreacted materials and acts as a back-up column in case the first scrubber is out of operation. Each scrubber contains two sieve plates and has an overall column efficiency of 65% (i.e., NTP = 1.3). Following the scrubber, ethyl chloride is finished and sold. The aqueous streams leaving the scrubbers are mixed and recycled to the reactor. A fraction of the CE recycled to the reactor is reduced to ethyl chloride. This side reaction will be called the reduction reaction. The rate of CE depletion in the reactor due to this reaction can be approximated by the following pseudo first order expression  

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Case study Interception of chloroethanol in an ethyl chloride process 165 where Henry s coefficient = 0,1 and NTP = 1.3. ITierefore,... 

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