Bruce Clements

Next Generation Oxy-Fired Systems: Potential for Energy Efficiency Improvement Through Pressurization

Oxy-fired combustion has been identified as a key technology needed for greenhouse gas mitigation because it is capable of producing a concentrated CO2 stream suitable for sequestration. This technology as applied to pulverized coal systems has recently been brought to a near-commercial status with several key world-wide demonstrations. A barrier to its adoption has been the large additional auxiliary power required for oxygen production and CO2 compression which results in low overall system efficiency. There have been various strategies proposed to address these efficiency issues. A very promising concept is the use of pressurized combustion in order to increase the system efficiency. The use of pressure increases the power requirement of the air separation system. However, pressurization increases the boiler and steam side efficiencies while decreasing the power requirement for the CO2 compression system. The use of pressure will also affect the performance and size of each piece of equipment within the system. This paper describes the efficiency benefit of using pressure as compared with a baseline ambient pressure oxy-fired system and a typical air-fired system. The technical aspects of various system layouts are presented, the overall efficiency is evaluated and the merits of specific configurations are discussed. Design issues of equipment associated with the fuel supply, furnace, ash removal, heat transfer and flame moderation systems are presented.Copyright

High pressure oxy-fuel (HiPrOx) combustion systems

Abstract: High pressure oxy-fuel (HiPrOx) is a derivative of basic oxy-fuel technology that has the potential to overcome some issues associated with ambient pressure oxy-fuel systems. It has application both in the power generation and the industrial sectors. Its development and interest have been sparked by requirements for CO2 capture and storage. This chapter describes the motivation and efficiency benefits of using pressure and technical approaches that are currently being considered. The central thrust of this chapter is to present the key concepts and focus on coal-fired Rankine and Brayton cycle power systems.