Pressurized fluidized bed combustion and gasification of coal using flue gas recirculation and oxygen injection

Abstract

A combined cycle incorporating pressurized fluidized bed combustion of coal with pure oxygen and recycled flue gas followed by pressurized combustion of the fuel gas using pure oxygen, is a process which produces electricity and heat with a high efficiency and a flue gas with a high CO2 concentration. CO2 recovery from this process can be done more easily than from conventional coal conversion processes. In this way a high efficiency coal conversion process can be realized with low CO2 emissions. The specific aim of the project is to assess the technical feasibility of this process. For this purpose a 1.6 MWth pressurized fluidized bed combustion test rig has been modified to study experimentally the gasification process and the pressurized combustion of the resulting low calorific value fuel gas. The objectives of the project, the modified test rig and the experimental results obtained from combustion experiments with coal, recirculated flue gas and pure oxygen are described. The conversion efficiencies and the emission of harmfull components measured during these experiments are analyzed and compared with values obtained during combustion and gasification using air.