Gas Turbine Uses Coal Fuel With Indirect Heat Transfer via Circulating Ceramic Beads

This paper defines a gas turbine power system in which the heat from coal combustion is transferred to a clean working gas by contact with a recirculated stream of hot ceramic beads. The beads are first heated by direct contact in a pressurized coal combustion zone and then the hot beads are separated, freed of coal ash and contacted directly with a pressurized gas such as air going to a gas turbine. Separate zones are used for combustion and for contact with the clean gas to be heated, and these two zones are kept separated by an intermediate column of beads at each transfer point. Similar technology is well known and used commercially in the petroleum industry, for example, in catalytic cracking of oil to make gasoline. Hot clean gas from the operation is used to generate power in an expander, while the products from coal combustion are handled by conventional methods for environmental control. The system offers the simplicity and efficiency typical of gas turbines and avoids the large use of water typical of steam power systems. Low investment is expected, together with minimal environmental impact.