DME (Dimethyl Ether) has emerged as a clean alternative fuel for diesel. There are largely two methods for DME synthesis. A direct method of DME synthesis has been recently developed that has a more compact process than the indirect method. However, the direct method of DME synthesis has not yet been optimized at the face of its performance: yield and production rate of DME. In this study it is developed a simulation model through a kinetics model of the ASPEN plus simulator, performed to detect operating characteristics of DME direct synthesis. An overall DME synthesis process is referenced by experimental data of 3 ton/day (TPD) coal gasification pilot plant located at IAE in Korea. Supplying condition of DME synthesis model is equivalently set to 80 N/m 3 of syngas which is derived from a coal gasification plant. In the simulation it is assumed that the overall DME synthesis process proceeds with steadystate, vapor-solid reaction with DME catalyst. The physical properties of reactants are governed by Soave-RedlichKwong (SRK) EOS in this model. A reaction model of DME synthesis is considered that is applied with the LHHW (Langmuir-Hinshelwood Hougen Watson) equation as an adsorption-desorption model on the surface of the DME catalyst. After adjusting the kinetics of the DME synthesis reaction among reactants with experimental data, the kinetics of the governing reactions inner DME reactor are modified and coupled with the entire DME synthesis reaction. For validating simulation results of the DME synthesis model, the obtained simulation results are compared with experimental results: conversion ratio, DME yield and DME production rate. Then, a sensitivity analysis is performed by effects of operating variables such as pressure, temperature of the reactor, void fraction of catalyst and H 2 /CO ratio of supplied syngas with modified model. According to simulation results, optimum operating conditions of DME reactor are obtained in the range of 265-275 o C and 60 kg/cm 2 . And DME production rate has a maximum value in the range of 1-1.5 of H 2 /CO ratio in the syngas composition.
The Korean pilot-scale gasification facility consists of a coal gasifier, hot gas filtering system, and acid gas removal (AGR) system. The syngas stream from the coal gasification at the rate of 100-120 Nm 3 /hr included pollutants such as fly ash, H 2 S, COS, etc. The acid gas, such as H 2 S and COS, is removed in the AGR system before generating electricity by gas engine and producing chemicals like Di-methyl Ether (DME) in the catalytic reactor. A hydrolysis system was installed to hydrolyze COS into H 2 S. The designed operation temperature and pressure of the COS hydrolysis system are 150 o C and 8 kg/cm 2 . After the hydrolysis system, COS was reduced below 1 ppm at the normal operating condition. The normal designed operation temperature and pressure of the AGR system are below 40 o C and 8 kg/cm 2 . Fe-chelate was used as an absorbent. H 2 S was removed below 0.5 ppm in the AGR system when the maximum concentration of H 2 S was 900 ppm. A small scale COS adsorber was also installed and tested to remove COS below 0.5 ppm. COS was removed below 0.1 ppm after the COS adsorbents such as the activated carbon and ion exchange resin.
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