ENVIRONMENTAL LOAD AND ECONOMIC ASSESSMENT FOR TOLUENE RECOVERY USING MEMBRANE SEPARATION

Sea, Bong-Kuk; Kim, Sung-Soo

Environmental Engineering Research 2001;6(2): 63-72.

¹New Energy and Industrial Technology Development Organization (NEDO), Tokyo 170-6028, Japan
²Department of Environmental Engineering, Catholic University of Pusan, Pusan 609-757, Korea

Corresponding Author: Bong-Kuk Sea ,Tel: +82-42-860-7247, Fax: +82-42-861-4151, Email: bksea@pado.krict.re.kr

Received: November 20, 2000; Accepted: March 20, 2001.

ABSTRACT

A new closed system using membrane separation for toluene recovery from industrial flue gas is proposed and evaluated from economical and environmental points of view. The system virtually prevents emission of organic solvent and is of a low environmental load type. To realize an optimum module design, material and energy flows of the process are calculated varying membrane-related parameters such as pressure ratio between feed and permeate sides, permeability, selectivity and feed concentration. The toluene recovery cost, which is calculated from the energy consumed by the compressor, cooler, vacuum pump and condenser, depends on feed concentration, selectivity and recovery rate. The relationship between recovery cost and selectivity strongly depends on the pressure ratio of the membrane unit. In the inventory analysis of the recovery system, for reducing recovery cost it was necessary to increase the toluene concentration in feed and toluene permeability of membrane to 2.0 vol% and order of 10^-7 mol • m/(m²- h ■ Pa). The environmental load evaluation through a cumulative CO₂ emission unit showed that compared to a conventional adsorption process, the closed membrane process was able to recover toluene with a lower environmental load.

Keywords: CO₂ emission | environmental load | membrane separation | toluene recovery | VOC