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Revamping Olefins Plant with Membrane Technology Disclosure Number: IPCOM000217280D
Publication Date: 2012-May-04

Publishing Venue

The Prior Art Database

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Vijender K. Verma

Technology Manager

The M.W. Kellogg Company

Chirstopher L. Phillips

Process Engineer

The M.W. Kellogg Company

Cong Dinh

Process Engineer

The M.W. Kellogg Company

Paper 22e

Preparedfor presentation at the American Instituteof Chemical Engineering Spring National Meeting, April 18,1994, Atlanta, Georgia

6th Ethylene Producers Conference

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economical approach in terms of investments per ton of additional capacity, and if properly carried out, it can also improve the overall process efficiency and perhaps improve feed flexibility. Depending upon the need and economics, the revamp can be carried out in many stages of increasing capital investment through process optimization, minor modifications, major debottlenecking, paralleling equipment or installing a parallel train. These revamp options available to ethylene producers should be studied diligently to meet the desired objectives such as low investment, reduced downtime, improved process efficiency, increased feedstock flexibility or modified product slate. The manner in which these modifications can be configured are limited only by the ingenuity of process engineers. Many new techniques are now available, first to identify plant limitations and inefficiencies,and then to overcome these.

M. W. Kdlogg has developed various schemes to meet the above revamp objectives. One novel method is the use of membranetechnology in which commercially available membranes are used to remove a portion of hydrogen contained in the pyrolysis gas. Use of membranes to separate hydrogen is commercially practiced for many years in various applications such as in recovering hydrogen from ammonia plant tail gas or

hydrotreater off gas, or to adjust H2/CO ratio in methanol or carbon monoxide plants. Membranes have been used in ethylene plants to purify hydrogen. However, the application of membranes for ethylene plant revamps is novel and is based upon the principal of "rejecting" hydrogen from the pyrolysis gas. After this hydrogen rejection,



by V. K. Verma, C. L. Phillips and C. Dinh

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the concentration of ethylene and heavier material increases substantially, such that more material can be condensed against warmer propylene refrigerants (PR). As a result, the flows and refrigeration loads in the ethylene refrigerant (ER) circuit are

Membrane Selection:

Commercially available membranes can be used for this application providedthey offer relatively high selectivity for hydrogen transport as compared to ethylene, and provided they are relatively stable at normal ethylene plant conditions. Selectivity is important to minimize ethylene loss in the rejected hydrogen, although, a small increase in overall ethylene loss may be economically acceptable. Use of commercially available modules of hollow fiber polyaramid membranes are quite suitable for this purpose.

Other variables which affect...