Process Design and Simulation of Coal Gasification

Abstract

Energy in demand today at both national and international level. Most of the resources of energy have been used. It is challenge of the day to cope with the energy problem. To overcome this problem, production of SYNGAS (CO+H2) using natural resources like coal is recommended which produces cost effective SYNGAS using coal gasification process which is environment friendly process. SYNGAS is used as fuel for internal combustion engines and used for production of Hydrogen which further is processed to produce Ammonia and Methanol. It is used as intermediate to produce synthetic petrochemicals via Fischer-Tropsch process. Our objective in this study is Modeling and Simulation of Coal gasification process to produce SYNGAS using Aspen Plus software and energy optimization of the whole process using Pinch technology. Capital cost of plant and utility cost of the process is calculated before and after energy optimization and then compared both costs. There are three types of gasifiers that are used for Coal gasification Process. First is Fluidized bed gasifiers here feed raw materials suspended the feed stock in an Oxygen rich gas which makes a bed in gasifier which act as fluid, efficiency of these gasifiers depends upon the reaction between feed stock and materials already going gasification process. Second is Moving bed gasifiers which are mainly used for gasification of biomass due to their lower operating temperature and flexibility in raw materials dimension. The last one is Entrained flow gasifiers, in this type of gasifiers feed stock, air or Oxygen and steam are fed at same time into the gasifiers. This study focused the process of Coal gasification using Entrained flow gasifiers is modelled and simulated in Aspen Plus ®. Nonconventional type of coal is defined and “enthalpy model” is “HCOALGEN,” which calculates the enthalpy of streams comprising coal. By simulated research, we calculate the behaviour of the actual process. After process simulation, it has been concluded that process can be controlled by controlling concentration of Oxygen and reactor temperature. When oxygen concentration increases in the reactor, Carbon is oxidized completely and produces useless by- products such as carbon dioxide, water and products of sulphur to enhance production. To produce SYNGAS, it is necessary that Carbon must partially be oxidized that is generating our desired product SYNGAS. Energy optimization of SYNGAS production process is done using Pinch analysis technique and using Pinch Technology recovered process energy which were iv wasted before and save 20.7 million $ per year which were consumed before for cooling and heating of streams.