Control device and control method using fuel supply acceleration command value

Abstract

A control device for a power generation system whereby power is generated by a first power source that operates by burning a fuel. The control device identifies, on the basis of a pressure difference in a prior-stage mechanism that supplies the fuel to the first power source, a fuel capacity that compensates for the pressure difference in the prior-stage mechanism. The pressure difference is the difference between a pressure set for the fuel before a load change in the prior-stage mechanism and a pressure set for the fuel after the load change in the prior-stage mechanism. The control device calculates a fuel supply command value, which is a command value for adjusting the amount of fuel supplied to a fuel supply device that supplies the fuel to the first power source, and is output to the fuel supply device using a fuel supply acceleration command value.

Claims

1. A control device of a power generation system which is configured to generate power by a first power source which is configured to operate by burning a fuel, wherein the control device is configured to calculate a fuel supply acceleration command value, which is a command value to accelerate a fuel supply for compensation of a volume difference of the fuel based on a fuel pressure difference in a prior-stage mechanism, which is configured to supply the fuel to the first power source, between a pressure of the fuel which is set before a load change and a set value of a pressure of the fuel after the load change in the prior-stage mechanism which is calculated based on a load requested to the power generation system, the fuel supply acceleration command value being a command value for adjusting an amount of the fuel supplied to a fuel supply device which is configured to supply the fuel to the first power source, based on a relationship between the fuel pressure difference and the fuel supply acceleration command value associated with each other in advance and recorded in the control device, and the control device is configured to calculate a fuel supply command value for output to the fuel supply device using a value which is obtained by adding the fuel supply acceleration command value, a gasifier input command correction value which is calculated based on a deviation between the set value of the pressure of the fuel and a measurement value of the pressure of the fuel, and a base fuel supply command value calculated based on an output command value with respect to the first power source which is obtained by subtracting an output value of a second power source from the output command value with respect to the power generation system.

2. The control device according to claim 1, wherein the base fuel supply command value is corrected using atmospheric temperature.

3. A control method of a power generation system which is configured to generate power by a first power source which is configured to be driven by burning a fuel, the control method comprising: calculating a fuel supply acceleration command value, which is a command value to accelerate a fuel supply for compensation of a volume difference of the fuel based on a fuel pressure difference in a prior-stage mechanism, which is configured to supply the fuel to the first power source, between a pressure of the fuel which is set before a load change and a set value of a pressure of the fuel after the load change in the prior-stage mechanism which is calculated based on a load requested to the power generation system, the fuel supply acceleration command value being a command value for adjusting an amount of the fuel supplied to a fuel supply device which is configured to supply the fuel to the first power source, based on a relationship between the fuel pressure difference and the fuel supply acceleration command value associated with each other in advance and previously recorded, and calculating a fuel supply command value for output to the fuel supply device using a value which is obtained by adding the fuel supply acceleration command value, a gasifier input command correction value which is calculated based on a deviation between the set value of the pressure of the fuel and a measurement value of the pressure of the fuel, and a base fuel supply command value calculated based on an output command value with respect to the first power source which is obtained by subtracting an output value of a second power source from the output command value with respect to the power generation system.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is an example of a configuration diagram of an IGCC.

(2) FIG. 2 is a diagram showing one example of an output control of the IGCC in a first embodiment according to the present invention.

(3) FIG. 3 is a diagram for explaining a determination method of a gasifier input acceleration command in the first embodiment according to the present invention.

(4) FIG. 4 is a diagram showing an example of an output control of the IGCC in a second embodiment of the present invention.

(5) FIG. 5 is a diagram showing an example of an output control of the IGCC in a third embodiment of the present invention.

(6) FIG. 6 is a diagram showing an example of an output control of the IGCC in the related art.

DESCRIPTION OF EMBODIMENTS

First Embodiment

(7) Hereinafter, an output control of an IGCC according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. The configuration of the IGCC is the same as the configuration which is described with reference to FIG. 1. A power generation system (IGCC) of the present embodiment is a power generation system which includes a first power source (gas turbine) which operates by burning a fuel, and a second power source (steam turbine) in which an output response is slower than that of the first power source, and drives a generator by the first power source and the second power source to generate power. The present embodiment is a method by which a control device 50 determines a gasifier input command (GID) which indicates a supply amount of a fuel such as coal, oxygen, or air which is supplied to a fuel supply device (gasifier).

(8) FIG. 2 is a diagram showing an example of the output control of the IGCC in the present embodiment.

(9) With reference to FIG. 2, an output control which is performed by the control device 50 in the present embodiment will be described.

(10) The control device 50 acquires a demand of a load, and determines a generator output command value (MWD) according to the load (S100). For example, the control device 50 acquires an output value of a generator 9 which is measured by an output meter included in the generator 9 (S101), and calculates a deviation between a generator output command and the output value of the generator 9 (S102). Next, the control device 50 controls the gas turbine such that the output of the generator 9 coincides with the generator output command (S103). Specifically, the control device 50 determines an opening degree of a gas turbine governor (GT GOV) 14 for correcting the deviation of the calculated output value, and controls the gas turbine governor 14 by the determined opening degree (S104). Accordingly, the control device 50 adjusts a fuel supplied to the combustor 5, and controls the output of the generator 9. For example, tables associated with the deviation of the output value and the opening degree of the gas turbine governor are recorded in a storage unit (not shown) included in the control device 50 in advance, and the opening degree of the gas turbine governor may be determined by reading the values.

(11) In addition, the control device 50 acquires a set value of a system gas pressure after a load change corresponding to the generator output command by a function FX. Next, the control device 50 calculates a difference between the system gas pressure set value before the load change and the system gas pressure set value after the load change. In addition, the system gas pressure set value before the load change is recorded in the storage unit in advance, and the control device 50 reads the value. Moreover, the control device 50 determines a gasifier input acceleration command (GIR) corresponding to the calculated difference (S105). In order to obtain the gasifier input acceleration command, a gas pressure difference and the gasifier input acceleration command (GIR) are associated with each other in advance and are recorded in the storage unit, the control device 50 may obtain the gasifier input acceleration command by reading the value from the storage unit, or may obtain the gasifier input acceleration command by interpolation calculation using the read value. In addition, the system gas pressure is a pressure of fuel gas in a gas pipe system of an outlet side of the gasifier 2. In addition, system gas is the fuel gas. In the present embodiment, on the basis of a pressure difference or a pressure ratio between the pressure of the fuel gas which is set before the load change in a prior-stage mechanism (gas pipe system) of the gas turbine and the pressure of the fuel gas which is set after the load change, the control device 50 identifies a volume of fuel which is required to maintain the pressure of the fuel gas which is set after the load change. In addition, the control device 50 calculates the gasifier input acceleration command of compensating for the required volume of fuel, and determines the supply amount of the fuel considering the calculated gasifier input acceleration command. The set fuel gas pressure may be a planned value which is calculated by simulation or the like, or may be a value which is measured in an actual machine. Moreover, the gasifier input acceleration command considering the volume of fuel is described below with reference to FIG. 3.

(12) Moreover, the control device 50 acquires the output value of the steam turbine which is measured by a predetermined method (S106), and calculates a difference between the output value and the generator output command (S107). For example, the output value of the steam turbine may be obtained through calculation by measuring pressures, temperatures, and flow rates at the inlet and outlet of the steam turbine. The calculated difference is an output command (GT MWD, gas turbine output command) with respect to the gas turbine. Sequentially, the control device 50 determines a base gasifier input command (GIDO) based on the gas turbine output command (S108). The base gasifier input command associated with the gas turbine output command is recorded in the storage unit in advance, the control device 50 may determine the base gasifier input command by reading the corresponding base gasifier input command using the gas turbine output command, or may determine the base gasifier input command by performing interpolation calculation on the read value.

(13) Moreover, the control device 50 determines the set value of the system gas pressure determined according to the generator output command using the function FX (S109). In addition, the control device 50 acquires the pressure (system gas pressure) which is measured by the pressure gauge 15 (S110). Moreover, the control device 50 calculates a deviation between the system gas pressures set value and the system gas pressure (S111). The control device 50 calculates gasifier input command correction which performs the system gas pressure control, based on the calculated deviation (S112). In addition, in order to calculate the gasifier input command correction, a method of a feedback control such as PI control is used.

(14) Finally, the control device 50 sums the gasifier input acceleration command (GIR), the base gasifier input command (GIDO), and the gasifier input command correction (S113). The summed value is the gasifier input command (GID) (S114). The control device 50 calculates each of a coal flow rate command (S115), an air flow rate command (S116), and an oxygen flow rate command (S117) based on the summed gasifier input command, and outputs each calculated value to each control point. In addition, the gasifier input command (GID) is an index for determining a flow rate of materials input to the gasifier, and the GID is used in a function set for each material to calculate a fuel flow rate (for example, coal) and an oxidizer flow rate (for example, air and oxygen).

(15) Next, the gasifier input acceleration command which is determined by the processing of S105 will be described.

(16) FIG. 3 is a diagram for explaining a difference of system gas holding amounts due to the difference of the system gas pressures before and after the load change when a load increases.

(17) First, the left drawing indicates a volume of a system gas when the pressure of the gas pipe system (prior-stage mechanism) before the load change is a. The right drawing indicates the volume of the system gas existing in the gas pipe system from before an increase of a load when the system gas pressure is increased so as to be b in a state where the system gas having a volume indicated by a reference numeral 21 is added at the time of the increase of the load. At this time, the volume of the system gas originally existing in the gas pipe system becomes a/b (reference numeral 22). In the related art, particularly without considering that the volume of the system gas is compressed at the time of the increase of the load, the feedback control (S112) which corrects the deviation between the measurement value of the system gas pressure and the set value is performed based on the base gasifier input command (S108) corresponding to the generator output command. Accordingly, time is required until the output value of the generator is settled.

(18) In the present embodiment, for example, in the example of FIG. 3, a feed forward control is performed using the gasifier input acceleration command (S105) in which the command value compensating for the system gas having the volume indicated by the reference numeral 21 is taken into consideration in advance. Accordingly, it is possible to decrease the deviation between the set value of the system gas pressure and the measurement value of the system gas pressure, and it is possible to decrease the time until the change of the system gas pressure is settled. Therefore, it is possible to stably operate the entire power generation plant even though the load change occurs.

(19) In addition, the gasifier input acceleration command at this time is the gasifier input acceleration command (GIR) considering the volume difference of the fuel gas based on the pressure difference of the fuel gas before and after the load change in the prior-stage mechanism of the gas turbine, that is, the gas pipe system on the outlet side of the gasifier 2 included in the pressure gauge 15. The gasifier input acceleration command is adjusted and determined by simulation and a trial operation in an actual machine.

Second Embodiment

(20) Moreover, in the first embodiment, in FIG. 2, the output command value with respect to the gas turbine is calculated by subtracting the output of the steam turbine from the generator output command. However, a method (second embodiment) is considered, in which the base gasifier input command is not determined based on the gas turbine output command, and is determined based on the generator output command. The second embodiment will be described with reference to the FIG. 4. FIG. 4 is a diagram showing an example of an output control of the IGCC in the second embodiment according to the present invention. In the present embodiment, as described above, the base gasifier input command is determined based on the generator output command (S108). Accordingly, not only the value which compensates for the change in the volume of the fuel gas due to the pressure change described with reference to FIG. 3 but also the value compensates for the change in the system gas pressure due to acceleration of the operation of the gas turbine is added to the gasifier input acceleration command (GIR) of the present embodiment. In the IGCC, in order to compensate for the delayed output response of the steam turbine and cause the output of the plant to follow the generator output command, the operation of the gas turbine is accelerated. However, at this time, the operation of the gas turbine is likely to generate the change in the system gas pressure. In the gasifier input acceleration command (GIR) in the present embodiment, a value (a power generation system acceleration command value) is used, which is calculated based on the output acceleration command value which is the command value input so as to suppress the change in the system gas pressure and the gasifier input acceleration command in the first embodiment. The output acceleration command value is a command value for suppressing the change in the system gas pressure generated by the operation of the gas turbine, and is adjusted and determined by simulation and a trial operation in an actual machine.

(21) In addition, the acceleration of the operation of the gas turbine is indicated by a in the following descriptions. In a case where the generator output command which is the load change of the entire plant is changed by X %/min, rates of change in the loads of the gas turbine and the steam turbine are also changed by X %/min. However, delay in the response in the output of the steam turbine occurs due to heat transfer to steam or the like. If the delay state is defined as a %/min, the rate of change in the load of the steam turbine becomes X-a %/min. At this time, in order to match the rate of change in the load to the rate of change in the generator output command of the entire plant, the rate of change in the load of the gas turbine is set to X+a %/min.

(22) According to the present embodiment, since the gasifier input acceleration command (GIR) considering the acceleration of the gas turbine operation is further used in addition to the gasifier input acceleration command in the first embodiment, even in a case where the steam turbine having a delayed output response is included in the plant, it is possible to suppress the change in the system gas pressure at the time of the load change. Accordingly, it is possible to stably operate the entire power generation plant even though the load change occurs.

Third Embodiment

(23) Hereinafter, an output control according to a third embodiment of the present invention will be described with reference to FIG. 5.

(24) FIG. 5 is a diagram showing an example of an output control of the IGCC in the third embodiment of the present invention.

(25) In FIG. 5, in the processing in the third embodiment, only portions of performing processing different from the processing of the first embodiment are shown. The processing which is not included in FIG. 5 is the same as the processing of FIG. 2.

(26) The control device 50 determines the generator output command corresponding to the demand load (S100). In addition, the control device 50 calculates the gas turbine output command (GT_MWD) by acquiring the output value of the steam turbine and subtracting the output value of the steam turbine from the generator output command (S107). Next, the control device 50 acquires the atmospheric temperature from a thermometer which is provided in the vicinity of the gas turbine compressor 7. Next, using a function, a table, or the like indicating a correlation between the base gasifier input command for each atmospheric temperature recorded in the storage unit in advance, and the gas turbine output command, the control device 50 calculates a base gasifier input command GIDO Tx which performs an atmospheric temperature correction with the acquired atmospheric temperature and the gas turbine output command as the conditions. The subsequent processing is similar to that of the first embodiment. That is, in the present embodiment, the control device 50 calculates the gasifier input command by adding the base gasifier input command GIDO Tx which performs the atmospheric temperature correction, the gasifier input acceleration command, and the system gas pressure correction value.

(27) According to the present embodiment, since the base gasifier input command is corrected according to the atmospheric temperature, it is possible to calculate a coal flow rate command value, an air flow rate command value, and an oxygen flow rate command value which are subjected to the atmospheric temperature correction. Accordingly, in addition to the effects of the first embodiment, it is possible to stably operate the entire power generation plant without being influenced by the atmospheric temperature. In the present embodiment, the first embodiment and the second embodiment can be combined.

(28) In addition, the gas turbine is an example of the first power source. In addition, the system gas pressure is an example of the fuel pressure which is set before the load change in the prior-stage mechanism. Moreover, the gasifier is an example of the fuel supply device which supplies the fuel to the first power source. In addition, the steam turbine is an example of the second power source having a delayed output response. Moreover, the gasifier input command is an example of the fuel supply command values. In addition, the base fuel supply command value is an example of the base fuel supply command values. In addition, the gasifier input acceleration command is an example of the fuel supply acceleration command values.

(29) In addition, a computer system is provided inside the above-described control device 50. Moreover, the process of each processing in the above-described control device 50 is stored in a computer readable recording medium of a program format, and the processing is performed by reading and performing the program using a computer. Here, the computer readable recording medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

(30) In addition, the computer program is distributed to a computer by a communication channel, and the computer which receives the distribution may carry out the program.

(31) In addition, the program may realize a portion of the above-described functions.

(32) In addition, the program may be a so-called difference file (a difference program) in which the above-described functions can be realized by a combination of the program and a program recorded in a computer system in advance.

(33) Moreover, the components in the above-described embodiments may be appropriately replaced by the well-known components within a scope which does not depart from the gist of the present invention. Moreover, the technical scope of the present invention is not limited to the above-described embodiments, and for example, the control device according to the present invention may be applied to a plant such as a Poly-Generation or an Integrated coal Gasification Fuel cell Combined cycle (IGFC) including a gasifier or a gas turbine. In addition, various modifications may be applied within a scope which does not depart from the gist of the present invention.

INDUSTRIAL APPLICABILITY

(34) According to the above-described control device and control method, the balances of the pressure and the temperature of the entire power generation plant are adjusted, and it is possible to stably operate the entire power generation plant even though the load is changed.

REFERENCE SIGNS LIST

(35) 1: coal supply equipment

(36) 2: gasifier

(37) 3: high temperature filter

(38) 4: gas purification unit

(39) 5: combustor

(40) 6: gas turbine

(41) 7: gas turbine compressor

(42) 8: steam turbine

(43) 9: generator

(44) 10: air separation device

(45) 11: air booster

(46) 12: HRSG

(47) 13: stack

(48) 14: gas turbine governor

(49) 15: pressure gauge