Development of a high-performance coal-fired power generating system with pyrolysis gas and char-fired high temperature furnace (HITAF). Progress report No. 12, September--December 1994

A concept for an advanced coal-fired combined-cycle power generating system is currently being developed. The first phase of this three-phase program consists of conducting the necessary research and development to define the system, evaluating the economic and technical feasibility of the concept, and preparing an R&D plan to develop the concept further. There are two basic arrangements of our HIPPS cycle. Both are coal-fired combined cycles. One arrangement is the 35% natural gas HIPPS. Coal is converted to fuel gas and char in a pyrolysis process, and these fuels are fired in separate parts of a high temperature advanced furnace (HITAF). The char-fired furnace produces flue gas that is used to heat gas turbine air up to 1400 F. Alloy tubes are used for these tube banks. After leaving the alloy tube banks, the gas turbine air goes through a ceramic air heater where it is heated from 1400 F to 1800 F. The flue gas that goes through the ceramic air heater comes from the combustion of the fuel gas that is produced in the pyrolysis process. This fuel gas is cleaned to remove particulates and alkalies that would corrode and plug a ceramic air heater. The air leaving the ceramic air heater needs to be heated further to achieve the efficiency goal of 47%, and this is done by firing natural gas in the gas turbine combustor. An alternative arrangement of the HIPPS cycle is called the All Coal HIPPS. With this arrangement, the char is used to heat the gas turbine air to 1400 F as before, but instead of then going to a ceramic air heater, the air goes directly to the gas turbine combustor. The fuel gas generated in the pyrolyzer is used as fuel in the gas turbine combustor. In both cycle arrangements, heat is transferred to the steam cycle in the HITAF and a heat recovery steam generator (HRSG)