JPS6036818A - Denitrating controller for composite cycle power generating plant - Google Patents

Abstract

PURPOSE:To perform rational denitrating control, by a method wherein a flow rate of a reducing material being injected is controlled at each turbine system so that a deviation between a desired value and a detected value corresponding thereto is brought to zero. CONSTITUTION:A deviation signal (g) represents a deviation between a desired value at each turbine system and an actual value, and is inputted as a desired value signal for a flow rate of the injected reducing material to a subtractor 18 through a PI computer 15 and an upper limit value 16. An output signal (i) from a second detector 17 is inputted as an actual signal for a flow rate of the injected reducing material to the subtractor 18. From the two signals, the subtractor 18 computes a deviation between a desired value and an actual value, and a deviation signal (j) thereof is inputted to a PI computer 19. A flow rate of a reducing material, injected to each denitrating device through a regulator 20 for a flow rate of the injected reducing material, is controlled so that a deviation is brought to zero by means of an output signal (k) from the PI computer 19. Addition of a total amount control function to an individual control system enables the other control systems to compensate each other for the one control system which is happened to be forced into a condition in which it is deviated out of a control range.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention utilizes several gas turbines of approximately equal capacity and heat generated by the exhaust gas of the gas turbines. Composite cycle generation '1L norant, which removes nitrogen oxides from the combustion generated gas by injecting a reducing substance such as ammonia into the combustion generated gas in a complex cycle power generation ground that is connected to at least one steam turbine driven by steam. [Technology of the Invention (-19 Background and Problems thereof)] The above-mentioned type of combined cycle power generation granite using the exhaust heat recovery method can be roughly divided into single-shaft type and multi-shaft type.-shaft type This is a type in which the power turbine, steam turbine, and generator are connected by a common shaft.In the multi-shaft type, the gas turbine and steam turbine are separated into separate shafts, and each The present invention is of a type in which a generator is coupled to the shaft.If the present invention is to be described according to this classification, - a structure in which a plurality of shaft-type products are provided in series;
And multiple gas turbine systems as opposed to multiple steam turbine systems! This applies to both types of multi-axis configurations installed in QJs, and in any case, it is intended for glands with multiple gas turbines.

The combined cycle power generation gland is constructed as shown in FIG. 1, illustrating a negative axis type case. In FIG. 1, a CP 1, a GT 2, a generator 3, and a steam turbine 4 are connected to each other via a common shaft 5.

The fuel whose vIj amount is controlled by adjusting the opening V of the fuel adjustment valve 6 is supplied to the combustor 7 together with compressed air from the compressor 1, where it is mixed and combusted at equal pressure to generate high-temperature and high-pressure combustion gas. . The gas turbine 2 is driven by this combustion gas. Exhaust gas from the gas turbine 2 is led to an exhaust heat recovery boiler 8 and steamed. Steam generated in the exhaust heat recovery boiler 8 is guided to the steam turbine 4 via the steam control valve 9.
Drive this. The steam passing through the steam turbine 4 is led to a condenser 10, where it is dehydrated. This cycle acid generating gland supplies fuel to the combustor 7 as an input and obtains FE gas output from the generator 3 as a final output.

Now, during exhaust heat recovery, the exhaust gas released into the atmosphere from the tj heater 8, that is, the combustor 1 gas of the combustor 7, contains N.
O, No.2. It contains nitrogen oxides such as NO3, which are generally referred to as NOx. This nitrogen saponification product is considered harmful, and its permissible amount is legally regulated. Therefore, in order to remove the nitrogen saponified products contained in the combustion generated gas,
V heat recovery? A denitrification device is installed in the furnace 8. A denitrification device is a device that reacts combustion generated gas with a reducing substance such as ammonia in a catalyst to reduce and remove nitrogen oxides into nitrogen and water. In that case, unreacted nitrogen oxides will be directly discharged into the atmosphere. For example, when using ammonia as a reducing substance, if the amount supplied is too small, unreacted nitrogen saponification products will increase;
With a large number of plows, unreacted ammonia is often discharged. In the former case, it is inconvenient and of course it would be boring (
In the case of 'D', ammonia itself is not only harmful but also economical (and also wasteful). It will be necessary to supply

The device for controlling the supply meter to this reduced product is 1 ton of denitrification.
tll #device.

A pre-injection method of steam (or water) into the flame plane of the combustor is also known as a method for reducing the amount of nitrogen saponide emissions. However, this method alone is insufficient.

Particularly, during the startup of a gas turbine, for example, the time delay in steam generation makes it impossible to obtain steam for steam injection, and this steam injection method cannot be applied. On the other hand, when the gas turbine is started, the temperature of the catalyst in the denitrification device is low, and the reduction reaction is insufficiently carried out, resulting in a transient increase in the amount of saponified nitrogen produced.

Conventionally, denitrification control was carried out for each individual gas turbine series, but due to the reasons mentioned above, the waiting W gas turbine series sometimes deviated from the 1i111 instantaneous yoke range or fell into a 6+ state close to it. There was a risk that the entire ground would emit nitrogen oxides exceeding the standard 1.1.

[Purpose of the invention]

The present invention considers the above points! 1. (Summary of the Invention) To achieve this purpose, the present invention is a denitrification control system that can perform more rational denitrification control during transient periods such as when starting a specific gas turbine. The invention provides a group of detectors for detecting the nitrogen oxide exhaust flow rate for each gas turbine series, an adding means for calculating the sum of the nitrogen oxide exhaust flow rates detected by the detector group, and a nitrogen oxide exhaust flow rate for the entire plant. total exhaust flow setting means for setting a target value of a nitrogen oxide discharge flow rate; and arithmetic control means for forming a target value of a nitrogen oxide discharge flow rate for each gas turbine series based on a deviation between the target value and the sum total. , a control unit group for controlling the injection flow rate of the reducing substance for each turbine series so as to make the deviation between the target value given by the arithmetic control means and the corresponding detected value of the detector to zero; It is characterized by having the following.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the present invention. In this embodiment, three cast turbines are used as an example of the number of turbines.
The first, second, and third individual controls are configured to perform denitrification control individually for the denitrification equipment provided in the exhaust heat recovery villa arranged in the exhaust gas system of each gas turbine. Device 11A.

This is an example of a case where 11B and IIC are provided, and the details will be explained below based on this.

Each individual flt control unit 11A, 118, 11C+
have the same internal +4 configuration, and although only the internal configuration of device 41A is shown in detail in the figure,
11C shall also be constructed in the same way as the device impression.
11B, IIC includes a detector 12 for detecting the nitrogen oxides produced in the exhaust gas of the gas turbine system, and a reducing substance injected into the denitration equipment, 171J, and An i2 detector 17 for detecting the near flow rate is provided. Each system of carbon dioxide j
The output signal al of the detector 12 of each phase 1 representing the non-flow ridge
, a2, and a3 are led to an adder 21, where the total discharge flow rate of the entire ground is calculated, and the total discharge flow rate is output.

This total discharge flow rate signal S is manually inputted to the subtractor O together with the crab accumulation oxide total discharge flow rate target Ilk signal C set by the setting device 4, and here the deviation between the two human input signals is expressed (G d
1, i.e., a signal d representing the deviation between the actual value of the quantity and the set target value is formed.

This signal d is led to the P1 computing unit B via the upper limit limiter 274, where it is connected to each individual control unit 11A, IIB.
, IJ, and C, a feed discharge flow rate target value signal e is formed. If so, the individual discharge flow rate target 11α is set to be equal to the total discharge flow rate target value. This signal e is transmitted to each turbine/
Regardless of the load condition, the upper limit (H7l) is commonly input to the subtractor 14 of each individual control device 11A, LIB, IIG via the silverware 13. In each of the individual control devices znA, IIB, and JIC, in addition to the (fi) from the upper limit limiter I3, the output 'lrU''ia l of the J-th detector 12 is also input to the subtracter 14. Here, an internal input deviation signal g is formed. This deviation signal g represents the deviation between the target value and the actual value for each turbine system, and is input to the Pi calculator 15 and the upper limiter 1.
The input signal is inputted to the subtracter 18 through the subtractor 18 as a target value signal for the injection flow rate of the reducing substance for denitrification.

Is the subtractor 18K injected with a 61-element substance (for example, Anne Sevenia)? jf :Ractual direct signal as second detector 17
Output 1, M'r4i7riEλ勺-IX? One person? ED
'ea Shiyo IQIr To r + 柘1@11- Sea LJ1, r
- Calculates the deviation between the target value and the actual first shift, and inputs the deviation signal j to the PI calculator 19; According to the output signal k of the PI controller 19, the flow rate of the reducing material injected into each denitrification device through the reducing material injection flow adjustment 8:20i is adjusted to 1 liter II so that the deviation becomes zero.

In the equipment shown in Fig. 2, when each gas turbine series is in stable operation, each individual 1liI side and 1 unit are in stable operation, and the total exhaust flow rate of the entire plant is set by the setting 8S22. Each individual f1il1 image device 11A, 11 so as to match the vIC claw target value.
B.

Individual Hi control is performed by JIC. For example, the amount of nitrogen oxide emissions σ1L from the turbine series consisting of:
ψ1'' is a case where the amount of nitrogen detected by the first detector 12 increases significantly and exceeds the control range due to excessive increase in the amount of nitrogen detected by the first detector 12. It greatly exceeded the target value of profit; - the sum of the output currents of 11゛, and the output of the calculator, in other words, P.
! Valley-side separate control device 11 given via q operator 2!5
A, 11+3, human power target value e for IIC is suppressed in the decreasing direction, temporary suppression n1il is normally 1
The same operation is performed in the control system operating ljll Mni, and each individual control is performed toward a smaller target value. This control operation is performed so that the deviation between the actual total discharge flow rate f value and the total discharge flow rate target value becomes zero. The above-described control operation is characterized in that a mutual assistance operation is performed in which the control of the series that deviates from the control range is supplemented by the control of other healthy series.

In the illustrated embodiment, the output signal e of the P11 arithmetic unit is sent to each individual control device LIA, IIB, IIG.
However, depending on the situation, it may be distributed according to an appropriate predetermined ratio.

In addition, although the above embodiment is illustrated on the premise of an analog city 1j control circuit, the calculation 8tl excluding the detection end and the operation end
The l mU circuit portion can also be realized by software using a computer.

〔Effect of the invention〕

As described above, according to the present invention, by adding all the overall control functions to the individual control system, the individual control system can perform the following operations such as when starting a specific gas turbine: 1ill rj
Even if a critical condition occurs that deviates from the 1 range, other healthy control systems will compensate by mutual aiding operation, making it possible to satisfy regulation values over a wider range, making this a more rational composite cycle photoelectric ground. The denitrification control device 4 can be provided.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an example of zero combined cycle power generation, and Fig. 2 is a system diagram showing an example of zero combined cycle power generation. FIG. 2 is a block diagram illustrating an example of one type of device. 1°゛° compressed length, 2... gas kubin, 3...
・Photoelectric machine, 4...Steam turbine, 5...411.5
...Fuel adjustment valve, 7...Combustor, 8...Exhaust heat recovery boiler, 9...Steam control valve, 10...Condenser, Ii
A, 11B, Il, C...Individual control device, 1
2...Nitrogen oxide discharge outflow, detector, +4, 18
, 23... Subtractor, l-5, 19, 25... P1 computing unit, 17... Reducing substance injection bIL amount detector, 20-mount reducing substance injection flow rate regulator, 21... Adder , 22...
・Chamber, A total oxide discharge flow rate setting device.

Claims (1)

[Claims] Combustion in a combined cycle power plant having a plurality of gas turbines and at least one steam turbine driven by steam generated using heat contained in the exhaust gas of these gas turbines. In a denitrification control device for a combined cycle power plant, which removes nitrogen oxides from generated gas by injecting reducing substances such as ammonia,
A group of detectors for detecting the nitrogen oxide discharge flow rate for each gas turbine series, an addition means for calculating the sum of the nitrogen oxide discharge flow rate for each nitrogen detected by the detector group, and an initial nitrogen oxide flow rate for the entire gland. a total exhaust flow rate setting means for setting a target value for the total exhaust flow rate, an arithmetic control means for forming a target value for the amount of oxidized oxides discharged from each gas turbine series, and a target value given from the arithmetic control means and the detection corresponding thereto. +3 for each turbine series to reduce the deviation from the detected value to zero! J'jj self-reduction (fli control of the injection flow rate of flesh, etc.), and a composite Nycle snake electric diode which is fully equipped. Runt denitrification!ti control device.