Utilization of coal in a combined cycle powerplant

Claim 1

A method for producing power from coal in a combined cycle powerplant employing a gas turbine engine formed of a compressor, a combustion chamber, and a turbine connected to a power output device, employing a steam turbine engine including a boiler and a steam turbine connected to a power output device and employing an auxiliary combustor, comprising the steps of: feeding coal into a partial gasifier; converting the coal into combustible fluids and combustible char in the partial gasifier such that the amount of char produced has a heating value less than the heating value of the coal fed into the partial gasifier; burning the char from the partial gasifier in an auxiliary combustor to produce a high temperature gas containing essentially all of the heating value of all of the char formed in the partial gasifier; transferring a first portion of the heat from the high temperature gas of the auxiliary combustor to the working medium gas of the gas turbine engine to raise the temperature of the working medium gas; transferring a second portion of the heat from the high temperature gas of the auxiliary combustor to the working medium fluid of the steam turbine engine to raise steam; transferring a third portion of the heat from the high temperature gas of the auxiliary combustor to the partial gasifier for converting the coal into combustible char and combustible fluids; burning the combustible fluid with the working medium gas of the gas turbine engine in the combustion chamber of the gas turbine engine to produce a high temperature working medium gas; expanding the working medium gases through the turbine of the gas turbine engine to power the gas turbine engine; exhausting the working medium gas expanded through the turbine into the auxiliary combustor to provide heat and oxygen to the auxiliary combustor; and expanding the working medium fluid through the turbine of the steam engine to power the steam turbine engine.

Claim 2

A method for producing power from coal in a combined cycle powerplant employing a gas turbine engine formed of a compressor, a combustion chamber, and a turbine connected to a power output device, employing a steam turbine engine including a boiler and a steam turbine connected to a power output device and employing an auxiliary combustor, comprising the steps of: feeding coal into a partial gasifier; converting the coal into combustible fluids and combustible char in the partial gasifier such that the amount of char produced has a heating value less than the heating value of the coal fed into the partial gasifier; burning the char from the partial gasifier in an auxiliary combustor to produce a high temperature gas containing essentially all of the heating value of all of the char formed in the partial gasifier; transferring a first portion of the heat from the high temperature gas of the auxiliary combustor to the working medium gas of the gas turbine engine to raise the temperature of the working medium gas; transferring a second portion of the heat from the high temperature gas of the auxiliary combustor to the working medium fluid of the steam turbine engine to raise steam; transferring a third portion of the heat from the high temperature gas of the auxiliary combustor to the partial gasifier for converting the coal into combustible char and combustible fluids; burning the combustible fluid with the working medium gas of the gas turbine engine in the combustion chamber of the gas turbine engine to produce a high temperature working medium gas; expanding the working medium gases through the turbine of the gas turbine engine to power the gas turbine engine; exhausting the working medium gas expanded through the turbine into the auxiliary combustor to provide heat and oxygen to the auxiliary combustor; and expanding the working medium fluid through the turbine of the steam engine to power the steam turbine engine.