Utilization of coal in a combined cycle powerplant

Claim 1

A method for producing power from coal in a combined cycle powerplant using a gas turbine engine formed of a compressor, a combustion chamber, and a turbine connected to a power output device, using a steam turbine engine including a boiler and a steam turbine connected to a power output device and using an auxiliary combustor, comprising the steps of: feeding coal having a total heating value Q t into a partial gasifier; converting the coal into combustible fluids and combustible char in the partial gasifier such that the amount of combustible fluids produced has a heating value which lies in a range of sixty to eighty percent (60-80%) of the total heating value Q t and the amount of char produced has a heating value Q char equal to a percentage of the heating value of the coal fed into the partial gasifier; burning the combustile fluids with the oxygen containing working medium gas of the gas turbine engine in the combustion chamber of the 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 output device of the gas turbine engine; exhausting the working medium gas expanded through the turbine into the auxiliary combustor to provide oxygen and an amount of heat Q e to the auxiliary combustor; burning all of the char from the partial gasifier in an auxiliary combustor using the oxygen and the heat Q e from the exhausted working medium gases to produce a high temperature gas; transferring an amount of heat from the high temperature gas of the auxiliary combustor to the working medium fluid in the boiler of the steam turbine engine to raise steam, the amount of heat being equal to the summation of a first amount of heat Q w which is less than Q e , (Q w <Q e ) and a second amount of heat Q sf such that the amount of heat (Q sf +Q w ) transferred to the working medium fluid in the boiler maximizes the efficiency of the combined cycle through supplementary firing; expanding the working medium fluid through the turbine of the steam engine to power the output device of the steam turbine engine; wherein the amount of char produced has a heating value Q char equal to the amount of heat Q sf transferred from the high temperature gas of the auxiliary combustor to the working medium fluid in the boiler of the steam turbine engine to raise steam (Q char =Q sf ); wherein the coal is consumed to produce energy and the turbine is isolated by the auxiliary combustor from harmful particulates produced by burning the char.

Claim 2

A method for producing power from coal in a combined cycle powerplant using a gas turbine engine formed of a compressor, a combustion chamber, and a turbine connected to a power output device, using a steam turbine engine including a boiler and a steam turbine connected to a power output device and using an auxiliary combustor, comprising the steps of: feeding coal having a total heating value Q t into a partial gasifier; converting the coal into combustible fluids and combustible char in the partial gasifier such that the amount of combustible fluids produced has a heating value which lies in a range of sixty to eighty percent (60-80%) of the total heating value Q t and the amount of char produced has a heating value Q char equal to a percentage of the heating value of the coal fed into the partial gasifier; burning the combustile fluids with the oxygen containing working medium gas of the gas turbine engine in the combustion chamber of the 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 output device of the gas turbine engine; exhausting the working medium gas expanded through the turbine into the auxiliary combustor to provide oxygen and an amount of heat Q e to the auxiliary combustor; burning all of the char from the partial gasifier in an auxiliary combustor using the oxygen and the heat Q e from the exhausted working medium gases to produce a high temperature gas; transferring an amount of heat from the high temperature gas of the auxiliary combustor to the working medium fluid in the boiler of the steam turbine engine to raise steam, the amount of heat being equal to the summation of a first amount of heat Q w which is less than Q e , (Q w <Q e ) and a second amount of heat Q sf such that the amount of heat (Q sf +Q w ) transferred to the working medium fluid in the boiler maximizes the efficiency of the combined cycle through supplementary firing; expanding the working medium fluid through the turbine of the steam engine to power the output device of the steam turbine engine; wherein the amount of char produced has a heating value Q char equal to the amount of heat Q sf transferred from the high temperature gas of the auxiliary combustor to the working medium fluid in the boiler of the steam turbine engine to raise steam (Q char =Q sf ); wherein the coal is consumed to produce energy and the turbine is isolated by the auxiliary combustor from harmful particulates produced by burning the char.

Claim 3

A method for producing power from coal in a combined cycle powerplant using a gas turbine engine formed of a compressor, a combustion chamber, and a turbine connected to a power output device, using a steam turbine engine including a boiler and a steam turbine connected to a power output device and using an auxiliary combustor comprising the steps of: feeding coal having a total heating value Q t into a partial gasifier; converting the coal into combustilble fluids and combustible char in the partial gasifier such that the amount of combustible fluids produced has a heating value and the amount of char produced has a heating value Q char equal to a percentage of the heating value of the coal fed into the partial gasifier; burning the combustible fluids with the heated working medium gas of the gas turbine engine in the combustion chamber of the 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 output device of the gas turbine engine; exhausting the working medium gases expanded through the turbine into the auxiliary combustor to provide oxygen and an amount of heat Q e to the auxiliary combustor; burning all of the char from the partial gasifier in an auxiliary combustor using the oxygen and the heat Q e from the exhausted working medium gases to produce a high temperature gas; transferring an amount of heat from the high temperature gas of the auxiliary combustor to the working medium fluid in the boiler of the steam turbine engine to raise steam, the amount of heat being equal to the summation of a first amount of heat Q w which is less than the amount of heat Q e ,i.e. (Q w <Q e ) and a second amount of heat Q 1 such that the amount of heat (Q 1 +Q w ) transferred to the working medium fluid in the boiler maximizes the efficiency of the combined cycle through supplementary firing; transferring an amount of heat Q 2 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 after the working medium gas passes through the compressor; expanding the working medium fluid through the turbine of the steam engine to power the output device of the steam turbine engine; wherein the amount of char produced has a heating value Q char , the sum of the heating value of the char Q char and the amount of heat Q e being greater than the sum of the amount of heat (Q 1 +Q w ) transferred from the high temperature gas of the auxiliary combustor to the working medium fluid in the boiler of the steam turbine engine to raise steam and the amount of heat Q 2 transferred from the high temperature gas of the auxiliary combustor to the working medium gas of the gas turbine engine Q char +Q e >Q 1 +Q w +Q 2 ); wherein the heating value of the combustible fluids produced and the amount of heat Q 2 transferred from the high temperature gas of the auxiliary combustor to the working medium gas of the gas turbine engine lies in the range of sixty to eighty percent (60-80%) of the total heating value Q t ; and wherein the coal is consumed to produce energy and the turbine is isolated by the auxiliary combustor from harmful particulates produced by burning the char.

Claim 4

A method for producing power from coal in a combined cycle powerplant using a gas turbine engine formed of a compressor, a combustion chamber, and a turbine connected to a power output device, using a steam turbine engine including a boiler and a steam turbine connected to a power output device and using an auxiliary combustor comprising the steps of: feeding coal having a total heating value Q t into a partial gasifier; converting the coal into combustilble fluids and combustible char in the partial gasifier such that the amount of combustible fluids produced has a heating value and the amount of char produced has a heating value Q char equal to a percentage of the heating value of the coal fed into the partial gasifier; burning the combustible fluids with the heated working medium gas of the gas turbine engine in the combustion chamber of the 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 output device of the gas turbine engine; exhausting the working medium gases expanded through the turbine into the auxiliary combustor to provide oxygen and an amount of heat Q e to the auxiliary combustor; burning all of the char from the partial gasifier in an auxiliary combustor using the oxygen and the heat Q e from the exhausted working medium gases to produce a high temperature gas; transferring an amount of heat from the high temperature gas of the auxiliary combustor to the working medium fluid in the boiler of the steam turbine engine to raise steam, the amount of heat being equal to the summation of a first amount of heat Q w which is less than the amount of heat Q e ,i.e. (Q w <Q e ) and a second amount of heat Q 1 such that the amount of heat (Q 1 +Q w ) transferred to the working medium fluid in the boiler maximizes the efficiency of the combined cycle through supplementary firing; transferring an amount of heat Q 2 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 after the working medium gas passes through the compressor; expanding the working medium fluid through the turbine of the steam engine to power the output device of the steam turbine engine; wherein the amount of char produced has a heating value Q char , the sum of the heating value of the char Q char and the amount of heat Q e being greater than the sum of the amount of heat (Q 1 +Q w ) transferred from the high temperature gas of the auxiliary combustor to the working medium fluid in the boiler of the steam turbine engine to raise steam and the amount of heat Q 2 transferred from the high temperature gas of the auxiliary combustor to the working medium gas of the gas turbine engine Q char +Q e >Q 1 +Q w +Q 2 ); wherein the heating value of the combustible fluids produced and the amount of heat Q 2 transferred from the high temperature gas of the auxiliary combustor to the working medium gas of the gas turbine engine lies in the range of sixty to eighty percent (60-80%) of the total heating value Q t ; and wherein the coal is consumed to produce energy and the turbine is isolated by the auxiliary combustor from harmful particulates produced by burning the char.