Pulverized coal drying system for pulverizer, pulverized coal drying method therefor, pulverized coal drying program, pulverizer, and integrated gasification combined cycle
An object of the present invention is to provide a pulverized coal drying system for a pulverizer, a pulverized coal drying method therefor, a pulverized coal drying program, a pulverizer, and an integrated gasification combined cycle capable of stably drying a carbonaceous feedstock irrespective of the type of the carbonaceous feedstock to be used. There is provided a controller ( 50 ) of a pulverizer ( 10 ) that dries a supplied carbonaceous feedstock by using a drying fluid and includes a flow rate controller that controls the flow rate of the drying fluid within upper and lower limits of the flow rate of the drying fluid that are set to dry a plurality of types of the carbonaceous feedstock having different moisture contents in such a way that the temperature of the drying fluid discharged from the pulverizer ( 10 ) approaches a target temperature.
1. A pulverized coal drying system for a pulverizer that dries a supplied carbonaceous feedstock by using a drying fluid, the pulverized coal drying system comprising:
a flow rate controller that controls a flow rate of the drying fluid within upper and lower limits of the flow rate of the drying fluid that are set to dry a plurality of types of the carbonaceous feedstock having different moisture contents in such a way that a temperature of the drying fluid discharged from the pulverizer approaches a target temperature, wherein
the drying fluid is a transport gas that transports the carbonaceous feedstock,
the upper and lower limits are set with respect to a predetermined amount of supplied carbonaceous feedstock in a state in which the drying fluid discharged from the pulverizer has the target temperature in such a way that the upper limit is the flow rate of the drying fluid for drying the carbonaceous feedstock containing a largest moisture content and the lower limit is the flow rate of the drying fluid for drying the carbonaceous feedstock containing a lowest moisture content, and
the target temperature is a temperature of the transport gas discharged from the pulverizer, the temperature being expected when the dried carbonaceous feedstock reaches a desired dryness.
2. The pulverized coal drying system according to claim 1 , further comprising a temperature setter that lowers the target temperature by a predetermined temperature when the flow rate of the drying fluid reaches the upper limit of the upper and lower limits and raises the target temperature by a predetermined temperature when the flow rate of the drying fluid reaches the lower limit of the upper and lower limits.
3. The pulverized coal drying system according to claim 1 , further comprising a temperature setter that changes the target temperature in such a way that a conversion ratio at which carbonyl sulfide is converted into hydrogen sulfide in a raw syngas generated when the carbonaceous feedstock is partially combusted into a gas approaches a predetermined reference conversion ratio.
4. The pulverized coal drying system according to claim 1 , further comprising a temperature setter that changes the target temperature in a raw syngas generated when the carbonaceous feedstock is partially combusted into a gas based on a flow rate of discharged water recovered from the raw syngas.
5. A pulverizer comprising the pulverized coal drying system according to claim 1 .
6. An integrated gasification combined cycle comprising:
a coal feeding unit including the pulverizer according to claim 5 ;
a gas turbine rotated by combusting at least part of a combustion gas generated in a gasification unit and purified;
a steam turbine rotated by steam generated in a heat recovery steam generator by using an exhaust gas discharged from the gas turbine; and
a generator linked to the rotary motion of the gas turbine and/or the steam turbine.
7. A pulverized coal drying method for a pulverizer that dries a supplied carbonaceous feedstock by using a drying fluid, the method comprising
a flow rate control step of controlling a flow rate of the drying fluid within upper and lower limits of the flow rate of the drying fluid that are set to dry a plurality of types of the carbonaceous feedstocks having different moisture contents in such a way that a temperature of the drying fluid discharged from the pulverizer approaches a target temperature, wherein
the drying fluid is a transport gas that transports the carbonaceous feedstock,
the upper and lower limits are set with respect to a predetermined amount of supplied carbonaceous feedstock in a state in which the drying fluid discharged from the pulverizer has the target temperature in such a way that the upper limit is the flow rate of the drying fluid for drying the carbonaceous feedstock containing a largest moisture content and the lower limit is the flow rate of the drying fluid for drying the carbonaceous feedstock containing a lowest moisture content, and
the target temperature is a temperature of the transport gas discharged from the pulverizer, the temperature being expected when the dried carbonaceous feedstock reaches a desired dryness.
8. A pulverized coal drying program for a pulverizer that dries a supplied carbonaceous feedstock by using a drying fluid, the program causing a computer to carry out a flow rate control process of controlling a flow rate of the drying fluid within upper and lower limits of the flow rate of the drying fluid that are set to dry a plurality of types of the carbonaceous feedstock having different moisture contents in such a way that a temperature of the drying fluid discharged from the pulverizer approaches a target temperature, wherein
the drying fluid is a transport gas that transports the carbonaceous feedstock,
the upper and lower limits are set with respect to a predetermined amount of supplied carbonaceous feedstock in a state in which the drying fluid discharged from the pulverizer has the target temperature in such a way that the upper limit is the flow rate of the drying fluid for drying the carbonaceous feedstock containing a largest moisture content and the lower limit is the flow rate of the drying fluid for drying the carbonaceous feedstock containing a lowest moisture content, and
the target temperature is a temperature of the transport gas discharged from the pulverizer, the temperature being expected when the dried carbonaceous feedstock reaches a desired dryness.