(42b) Feasibility Analysis of Precombustion CO2 Capture in IGCC Power Plants Using MgO-Based Solid Sorbent

Climate Change, which has been associated with increasing concentration of greenhouse gases is regarded as one of the key environmental issues in the 21^st century. Carbon dioxide (CO₂) is the primary greenhouse gas emitted through human activities. Coal-fired power plants  still generate a major portion of electricity in the  U.S. and globally.and  national and global reliance on coal for electricity generation is expected to continue to be significant in the next several decades. Advanced coal based power generation technologies, such as Integrated Gasification Combined Cycles (IGCC) processes, are expected to be among the leading contenders for power generation because of their higher efficiencies, flexible products and potential environmental advantages compared to conventional coal combustion (pulverized coal) processes. The three general categories of CO₂ capture technologies that can be applied to coal-based power plants are pre-combustion, post combustion, and oxy-combustion. Pre-combustion technologies in IGCC processes involve separating CO₂ before the fuel is combusted. The high temperature of syngas in the outlet of gasifier suggests that MgO-based sorbents can be a good candidate for Carbon capture processes because its temperature-pressure equilibrium is in the operating range of industrial power plants. The syngas leaving the gasifier is cleaned up of other contaminants (Sulfur, particulates etc.) and then enters the carbon capture unit before entering to the turbines. This paper addresses the process design and economic feasibility of a Carbon Capture and Storage (CCS) process involving regenerable MgO-based sorbents for an IGCC power plant. The process consists of several circulating fluidized beds (CFB) operating at elevated temperature and pressure, to capture CO₂ in a carbonator reactor and regenerate the sorbent in a fluidized bed regenerator.  A make-up stream also enters the system to compensate the sorbent degradation as it goes through carbonation/regeneration cycles. Cost analysis demonstrate the make-up flow rate is the major source of operating cost in such a system.