Assessment of retrofitting possibility of an Indian pulverized coal boiler for operation with Indian coals in oxy-coal combustion mode with CO2 sequestration

Coal is the mainstay of electrical power generation in India. In this study, an experimental and theoretical assessment is made of the possibility of retrofitting an existing pulverized coal boiler for operation in oxy-coal mode. Experiments have been conducted using non-isothermal thermogravimetric analysis for a typical Indian coal to assess its reactivity under simulated oxy-coal combustion. Computational fluid dynamics simulations of a tangentially fired, 210MWe pulverized coal boiler of a typical Indian design have been carried out with a typical Indian coal composition to study the relative effect of oxy-coal mode operation on the flow and heat transfer characteristics within the boiler. A process flow diagram has been developed for a 662MWt power plant to include a retrofitted boiler and CO2 sequestration. It is concluded that a 70: 30 volumetric mix of CO2 to O-2 in the oxidizer composition will leave the essential features of the flow, temperature and heat transfer characteristics more or less unchanged, thus enabling retrofitting. An overall thermal efficiency loss of 11% is estimated for a retrofitted plant which delivers a flue gas which does not require chemical means of CO2 sequestration.