JPS6267241A - Control device of gas turbine - Google Patents

Abstract

PURPOSE:To reduce the density of exhaust gas, by furnishing plural fuel feeding systems and feeding the premixed fuels in turn to a combustion tube, while controlling the premixing ratio of fuels to get an adequate exhaust gas density value. CONSTITUTION:At the passage to feed the first system fuel f1 to a burner 2, a flow adjusting valve 9 is furnished, while at the passage to feed the second system fuel f2 to the burner 2, a flow adjusting valve 9a is furnished. At the exhaust of the turbine 12, an exhaust temperature sensor 17 and an exhaust gas NOx sensor 18 are furnished, and, the temperature signal and the NOx quantity signal are fed as a feedback to a controller 16. The opening of the valve 9a is adjusted to control the premixing ratio in order to keep the NOx quantity at an adequate value. Therefore, the exhaust gas density of NOx and the like can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control device for a gas turbine, and more particularly to control equipment for controlling NOx pollution emissions from a gas turbine. This invention relates to a gas turbine control system that enables 1I11 control.

[Technical background of the invention and its problems] FIG. 5 is a block diagram of a basic gas turbine device, in which air compression II
The compressed air becomes high-pressure air and flows into the combustor 2. - the combustor 2 has a cylindrical combustion tube 3;
An outer cylinder 5 is disposed concentrically to form an annular region 4 on the outer periphery of the combustion cylinder 3, and a fuel nozzle 6 is provided at one end of the combustion cylinder 3. Therefore, the high-pressure air that has flowed into the combustor 2 passes through the annular region 4 formed by the combustion tube 3 and the outer tube 5, and cools the combustion tube 3 by forced convection while cooling the outer peripheral wall of the combustion tube 3. The air flows into the combustion tube 3 through an air hole 7 formed in the air hole 7 and a swirler 8 formed on the outer periphery of the fuel nozzle 6 . On the other hand, the flow rate of the fuel is controlled by the fuel 18 regulating valve 9 in accordance with the gas turbine load λ1, the fuel is injected into the vicinity of the backflow region 1o in the combustion cylinder 3 by the fuel v1 nozzle 6, and is ignited by the ignition device 11. The swirler 8 and the high 1F air flowing in through the air holes 7 are combusted together, constant volume and constant pressure combustion continues, and fringe gas is generated. But this? The third gas is guided to the gas turbine 12 to generate power, and a part of this power is consumed as driving power for the air compressor 1, and the remaining power is used to drive a driven 1113 such as a generator. Consumed as power.

However, in the combustor 2, the fuel nozzle 6 is
11IIIJ, or even in the case of multiple J
, the so-called thermal N
A large amount of NOx, called OX, is generated.

In order to reduce this NOx, it is necessary to inject water or steam.
method is widely used. In other words, by injecting water into the combustor, the combustion temperature is lowered and the generation of thermal NOX is prevented.A water injection &+ curve is set for the normal fuel flow rate (), and the furnace fuel flow rate is With the increase in water jet 04 crystal, appropriate exhaust gas NOx
I am trying to make it so that

Furthermore, the predicted amount of exhaust gas NOx is calculated from the air flow rate and fuel a1 in the 111 control system, and the water injection 1f) control r
Control the water jet OA section to adjust the iF plowing gas N.
Optimal control to achieve Ox W+! There are 7J laws that apply. , 1, I, Special Publication No. 57-27971, 2
As shown, directly detects exhaust gas NOx,
The NOx value of a is determined and appropriate (1 gas NOx I
A method has been proposed for adjusting the amount of water jetted so as to achieve the I standard.

However, all of these NOx reductions use water or steam, and their effectiveness is limited.
1. It doesn't look good, and combustion vibrations are likely to occur. Furthermore, in the case of a waste heat recovery boiler, etc., it is customary to obtain steam for injection using a waste heat recovery boiler. If steam cannot be obtained, the flow rate of fuel Fl is kept small until the steam condition f1 is established, and A-mink of the long reIrEJ waste heat recovery boiler is continued. As μ increases, the a-1 limit of operation 1 and 6 become (there are.

By the way, it is known that a premixing method is effective as a method for realizing a local reduction in flame temperature. In other words, Figure 6 shows the change in NOx with respect to the fuel-air ratio.
This figure shows that when there is no premixing, the NOx generation at 1F is as shown in curve A, whereas when premixing is performed under lean conditions, for example, NOx generation increases according to the premixing. becomes like curve B, which makes it possible to lower the local flame temperature and reduce NOx.

FIG. 7 is a schematic diagram illustrating the basic configuration of a combustor using the premixing method, in which a premixing chamber 14 is formed on the outside of the combustion tube 3. The second fuel flow 18 regulating valve 9a allows the fuel whose flow rate is adjusted to be transferred to the mixing chamber 14.
It is premixed with high air before flowing into the combustion cylinder 3, and burns through the plurality of holes 15 provided in the premixing cylinder 14! ! 13. Then, τ is present in the combustion tube 3 and is ignited by the high temperature gas generated by combustion of the fuel injected from the fuel nozzle 6, and is combusted at a low combustion temperature, suppressing the generation of NOx 1F.

The exhaust gas levels corresponding to the NOX and COW gas turbine loads in such a device are as shown in Figure 8.
During gas turbine load operation near the rated load, NO
It is possible to sufficiently clear x criterion f, II value a, and CO criterion i, 11 value. However, as can be seen from this figure, during partial load operation, NOx,
Both CO levels greatly exceed regulation values a and b.

(Objective of the Invention) In view of these points, the present invention provides a plurality of fuel systems, supplies premixture in stages over multiple stages, and adjusts the premixing ratio to achieve an appropriate exhaust gas NOx value. It is an object of the present invention to provide a gas turbine control device which effectively reduces NOx by controlling the amount of NOx and which does not have the above-mentioned problems.

(Summary of the Invention) The present invention includes a plurality of fuel systems, each of which can control the fuel flow rate to a combustor, and a fuel system other than the fuel system that injects fuel from a fuel nozzle, premixing each fuel with high-pressure air, Controls the sum of the fuel flow rates of multiple systems according to the multiple mixing chambers that supply premixed fuel into the combustion cylinder and the turbine load, and sequentially switches from the fuel system A to the multiple fuel systems. The premixed fuel is supplied in stages, and the exhaust gas values such as NOx are adjusted to an appropriate level.
Combustion 1. Controlling the ratio of the above premixing so as to produce clay. I
It is characterized by having the following features:

[Embodiments of the invention]

An embodiment of the present invention will be described below using an example of a system using two systems of fuel, that is, a system using a premix combustor shown in FIG. 7.

In FIG. 7, the fuel f1 of the first system is supplied to the fuel nozzle 6 provided at one end of the combustion tube 3 via the fuel flow m regulating valve 9, and a part of the fuel is compressed by air. It is supplied into the combustion tube 3 through the swirler 8 along with a portion of the high-pressure air fed from the machine 1, and combustion is performed there.

By the way, an independent premixing chamber 14 is provided on the outer periphery of the combustion tube 3, and the premixing chamber 14 is filled with the fuel of the second system. After being premixed with a portion of the high-pressure air discharged from the air compressor 111, the air is injected into the combustion cylinder 3 through the hole 15 provided in the premixing chamber 14. and burned in the relevant section.

Incidentally, as shown in FIG. 2, the fuel flow rate regulating valves 9 and 9a are operated and controlled by output signals from the combustion mi controller 16, respectively.
The fAvJ increase/decrease signal is input to 6, and the exhaust temperature sensor 1 installed at the exhaust part of the turbine 12 is inputted to 6.
Exhaust temperature signal from exhaust gas NOx sensor 18, NOxffi signal from exhaust gas NOx sensor 18, and gas turbine speed sensor 1
The na signal from 9 is fed back, and furthermore, the valve opening signals from the valve opening detectors 20 and 21 provided in each fuel flow (iltJ!l regulating valve 9, 9a) are fed back.

FIG. 1 is a block diagram of the combustion control unit 16, in which the gas turbine load increase/decrease signal is controlled by the combustion control unit II.
When inputted to the load setting device 22 of the device 16, the negative 61 setting device 22 is activated and a load command is output, and this load command is 3! Speed signal obtained from degree hinter 19 and comparator 23
The difference signal is input to the low value priority circuit 25 via the speed tU load control section 24. The low value priority circuit 25 has the output of the exhaust temperature 1!111I control section 26 which inputs the exhaust temperature signal from the exhaust temperature L sensor 17, and the output of the start-up control section 27, which are also manually operated. A fuel request command signal Q is output depending on the low values of the three signals.

The low value priority circuit 25 is used to take advantage of the exhaust temperature 11111+ signal for gas turbine protection in priority over the fast-generating load signal, and to perform fuel control at startup, and is normally used even if the exhaust temperature is within the limit. For example, a fuel request command signal Q is output in response to a load command.

By the way, the fuel demand command signal 9 is generated by the first function? A28 is input to the second function generator 29, and the first
The function generator 28 outputs a flow rate command signal of the first system fuel Flf1 corresponding to the fuel demand command signal Q,
The bias signal from the bias setting device 31 is subtracted from this signal by a subtracter 30, and the deviation signal becomes a valve lift signal by a flow rate-valve lift converter 32, and the fuel flow m The fuel flow m is inputted to the regulating valve 9, and the opening degree of the fuel flow m regulating valve 9 is controlled. Moreover, the opening speed of the fuel flow rate regulating valve 9 is the valve Ili! @Detected by the detector 20 and fed back to the subtracter 33.

On the other hand, in the second function generator 29, when the turbine load reaches a predetermined value in the low load range, the fuel request command signal 0
A flow rate command signal for the fuel f2 in the second system is output in response to this, and the bias signal from the bias setting device 31 is added to this signal in the converter 35, and the output signal is converted to the flow rate command signal in the valve lift converter 36. It became a lift signal, and 37 each of the towers were reduced.
It is input to the fuel flow m regulating valve 9a via the power amplifier 38, and the opening degree of the fuel flow m regulating valve 9a is set to f, II lit. The opening of the fuel flow regulating valve 9a is detected by the valve opening detector 21 and fed back to the n reducer 37.

Here, the function generators 28 and 29 are configured in advance to
Car 1 set to keep II output within the appropriate value
This determines the share of the second fuel flow regulating valve 9a that performs 1'J of premixing with respect to the fuel flow rate command signal q.
Further, the bias setting device 31 is used to smoothly control the fuel when the second fuel flow rate control valve starts to open.

On the other hand, the NOx value obtained by the NOx sensor +j-18 is compared with the NOx set value by the reducer 39, and a control command for eliminating the NOx amount deviation is calculated by a III controller 41 such as a proportional integrator. Q is applied as a bias signal to the filter 30 and 35. Therefore, this bias signal acts to modify the function curve 28.29 determined based on the fuel flow part 0 by NOx i),
For example, if the weather conditions (wet garden, atmospheric temperature, etc.) change from the expected NOx generation, the premixing ratio can be changed, and NOx
It is possible to control l to an appropriate value.

FIGS. 3(a) and 3(b) are diagrams showing the state of the first control, respectively, and the lines a and [) in FIG. 3(a) respectively indicate the preset leap number shots/1. This is a curve for the negative A of the fuel flow rate obtained by the fuel flow control valve 9.98 J, which is accommodated by the valves 28 and 29. So, for example, NOx
If Kō has one arm as shown in d in Figure 3<8), NO
x') A deviation occurs between planting and NOx hanging, and the controller 41
, the repair bias signal is output, and the fuel flow adjustment valve 9
The fuel flow rate caused by a is increased as indicated by f in FIG.
ffiq is held constant. However, at -), the premixing ratio increases and NOxffi is controlled in a decreasing direction so that it approaches the NOX set value, and finally the NOx concentration decreases to NOx.
Controlled by the X setting value.

By the way, if you want to control h of C0IJl more actively than NOx emission, you can control CO
It is sufficient to provide a sensor and control the NOx control section as if it were a CO control section. That is, since the reduction in NOx and the increase in CO are in an inverse relationship, if it is desired to control CO, the increase in CO can be suppressed by slowing down the NOx reduction rate. In addition, if you want to control λCO in addition to NOx, you can install a NOx control section, a COII, and an IJ control section (), and a control circuit that selects the minimum value of the output of both control sections with a low value priority device and adds it as a bias signal. do it.

In other words, as shown in FIG. 4, the CO set value 44 and CO
Based on the deviation signal from the CO amount signal from the sensor 45, a control command for eliminating the deviation is processed by the controller 46, and the control command signal is input to the low Mi priority device 47. On the other hand, the control command signal from the tIII controller 41 is also input to the low value priority device 47, and the low value of both control command signals, that is, the ljl timl output that has reached the control target of either NOx or CO. is selected and multiplier 4
At step 8, a flow rate command signal to be sent to the fuel flow control valve 9 is created from the fuel flow rate command signal q. On the other hand, based on this signal and the fuel flow rate command signal Q, a fuel flow rate command signal for premixing is created in the attenuator 49, and the opening degree of the second fuel flow regulating valve 9a is controlled.

Although two systems of fuel control have been described in the above embodiment, three systems or the like may be used depending on the NOx emission ω, etc. Further, the exhaust gas ll& may be an expected exhaust gas value obtained from an oil cylinder based on air flow rate, fuel flow environment, etc.

(Effects of the Invention) As explained above, in the present invention, a plurality of fuel systems are provided to sequentially supply premixed fuel into the combustion cylinder in stages, and the premix ratio is adjusted to Since the exhaust gas concentration is controlled by m'1J, it is possible to reliably prevent the exhaust gas concentration from exceeding the regulated supply in the entire load range, and it is possible to operate the high-efficiency B gas turbine. Moreover, since it does not inject water or steam, there is no reduction in efficiency.

[Brief explanation of drawings]

Figure 1 shows the features of the present invention! Combustion controller in control shield 7
Figure 2 is a schematic system diagram of the f and II control devices of the present invention, and Figures 3 (a) and (b) are the fl-IJ of the present invention, respectively.
J explanatory diagram, FIG. 4 is a control block [-1] of another embodiment of the present invention.
Figure 5 is a configuration diagram of the basic gas turbine equipment.
FIG. 6 is a NOx change diagram with respect to fuel-air ratio, FIG. 7 is a configuration diagram of a premixing type low NOX turbine, and FIG. 8 is an exhaust gas characteristic diagram of the gas turbine shown in FIG. 7. 1...Air f [compressor, 2...Combustor, 6...Fuel nozzle, 9.9a...Fuel Fl flow rate adjustment valve, 14...
Premixing chamber, 16... Combustion suppressor, 18... Exhaust gas N
Ox top-128...first function generator, 29...
- Second function generator, 31...bias setting device. Applicant Raccoon Person Sato - Male Figure 2 0 (%) - (b) Figure 3 Soot Sky Ratio

Claims (1)

[Scope of Claims] 1. A plurality of fuel systems each capable of controlling the fuel flow rate to the combustor, and a fuel system other than the fuel system that injects fuel from a fuel nozzle are premixed with high-pressure air,
Multiple mixing chambers supply the premixed fuel into the combustion cylinder, and the total fuel flow rate of multiple systems is controlled according to the turbine load, and a single fuel system is sequentially switched to multiple fuel systems. A gas turbine control device comprising a combustion controller that supplies the premixed fuel in stages and controls the ratio of the premixing so that the exhaust gas concentration becomes an appropriate value. . 2. The gas turbine control device according to claim 1, wherein the exhaust gas concentration is detected by an exhaust gas sensor. 3. The gas turbine control device according to claim 1, wherein the exhaust gas concentration is an expected exhaust gas value obtained by calculating based on air flow rate, fuel flow rate, etc.