JPH0286928A - gas turbine combustion system - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas turbine combustion system, and particularly to a gas turbine combustion system in which a plurality of types of fuels having different calorific values per unit amount, such as coal gasified fuel and oil or natural gas fuel, are selected. a fuel nozzle, a low calorific value fuel nozzle arranged around the outer periphery of the high calorific value fuel nozzle and injecting low calorific value fuel into the combustion chamber, and a low calorific value fuel nozzle arranged around the outer periphery of these fuel nozzles to inject combustion air into the combustion chamber. A gas turbine combustion system comprising: a jetting air nozzle.

10. The gas turbine combustion system according to claim 8 or 9, wherein the branch flow path is provided with a pressurizing means for pressurizing the air flowing through the flow path.

11.Claim 8 or 9 or 10
2. The gas turbine combustion system according to item 1, wherein the branch flow path is provided with a backflow prevention means.

12. In claim 8, the fuel supply system includes a low calorific value fuel supply system that supplies coal gasified fuel and a high calorific value fuel supply system that supplies fuel that has a higher calorific value per unit amount than the coal gasified fuel. The branch flow path relates to a gas turbine combustion system that can selectively use the extracted air when the fuel supply system supplies fuel with a large calorific value.

[Conventional Technique m1 A combustion system for a gas turbine that drives a generator is configured to be able to selectively use a plurality of types of fuel from the viewpoint of fuel economy and the like. Commonly used fuels are high calorific value fuels such as oils such as diesel oil and kerosene, and natural gas, and low calorific value fuels such as coal gasified fuels.

FIG. 11 is a system diagram of a gas turbine combustion system in a coal gasification combined cycle power generation system that uses oil fuel, which is a high calorific value fuel, and coal gasified fuel, which is a low calorific value fuel, as fuel.

A compressor 2 directly connected to a gas turbine 1 compresses atmospheric air and supplies it to a combustor 3 .

A portion of the air discharged from the compressor 2 is extracted, cooled by an air cooler 4, boosted by a booster compressor 5, preheated by an air preheater 6, and supplied to a coal gasifier 7. The auxiliary compressor 8 is used to supply air to the coal gasifier 7 until the oil air is supplied. The coal gasifier 7 reacts the air with the pulverized coal supplied from the coal supply device 9 to produce C○, H2, Co2. A coal gasification fuel supply system that generates a mixed gas such as H2O and supplies purified coal gasification fuel to the combustor 3 via the gas purification device 10 is configured.

The combustor 3 burns the coal gasified fuel supplied from the coal gasified fuel supply system or the oil fuel supplied from the oil fuel supply system 11 with the air supplied from the compressor 2 to produce combustion gas. Supplied to the gas turbine 1.

In such a gas turbine combustion system, at startup, first an external drive source (not shown) directly connected to the turbine 1 is activated.
The compressor 2 is driven to increase the speed to about 20% of the rated rotational speed of the gas turbine 1. Then, when the amount of air necessary for combustion is obtained from the compressor 2, oil fuel is started to be supplied to the combustor 3 from the oil fuel system 11, and ignition is performed. When combustion starts in the combustor 3 and combustion gas is supplied to the gas turbine 1, the rotational speed of the gas turbine 1 increases, and as the supply of coal gasified fuel starts, the supply amount of oil fuel is gradually reduced. This will eventually lead to a transition to the sole combustion of coal gasified fuel.

The gas turbine combustion system in such a coal gasification combined cycle power generation system was disclosed in the research report commissioned by Electric Power Development Co., Ltd., "Feasibility Study on the Practical Application of Coal Gasification Power Generation Equipment" (March 1980, P. 1-42). ing.

[Problems to be Solved by the Invention] However, in such a gas turbine combustion system, when the fuel used is oil fuel with a high calorific value and when the fuel used is coal gasified fuel with a low calorific value, The flow path of the discharged air changes, and the amount of air required by the combustor 3 also changes. However, the air output of the compressor 2 and the air flow path within the combustor 3 are generally designed for operation with low calorific value fuels, so when operating with high calorific value fuels, the air flow path within the combustor 3 is There is a problem that the pressure loss becomes large and the combustion state within the combustion chamber becomes unstable, resulting in a decrease in efficiency.

Accordingly, the rotational speed of the compressor 2 also increases. When the amount of oil fuel supplied is gradually increased, the rotational speed of the gas turbine 1 further increases and finally reaches the rated rotational speed. When the rated rotational speed is reached, the amount of air discharged from the compressor 2 becomes a substantially constant value.

In this state, a load is applied to a generator (not shown) directly connected to the gas turbine 1, and the amount of oil and fuel supplied is increased as the load increases.

If you are planning to switch to coal gasified fuel for operation,
When the load reaches 25% to 50% of the rated load, the flow of air discharged from the compressor 2 is started. The extracted air is cooled by an air cooler 4, boosted by a booster compressor 5, preheated by an air preheater 6, and then supplied to a coal gasifier 7. The auxiliary compressor 8 supplies air to the coal gasifier 7 until the oil/air is supplied. The coal gasifier 7 reacts the air with the pulverized coal supplied from the coal supply device 9 to produce Go, H2, Co2. A mixed gas such as H and O is generated, and the purified coal gasified fuel is started to be supplied to the combustor 3 via the gas purification device 10.

That is, when burning coal gasified fuel, a predetermined gas temperature is obtained by reducing the amount of air per unit amount compared to when burning oil fuel.

For example, the calorific value of coal gas produced from domestic coal in an entrained bed gasifier is 900kcal/Nm3 to 1000k.
cal/Nma, whereas the calorific value of ordinary oil and natural gas is 10,000 kcal/Nm3, which is approximately 1
Since there is a difference of 0 times, in order to obtain the same output as in the case of high calorific value fuel operation, a fuel flow rate that is 10 times the high calorific value fuel flow rate is required. On the other hand, during low calorific value fuel operation, the amount of air supplied to the combustor 3 is small by the amount of air used for coal gasification, which is the low calorific value fuel;
The air flow path is designed to effectively utilize this small amount of air to improve the cooling inside the vessel and the combustion efficiency of the high-velocity fuel. In particular, the flow path in the cooling section is narrowed to increase the flow rate and increase the cooling effect.

When the combustor 3 designed in this way is operated using oil fuel, which is a fuel with a high calorific value, there is no need for air in the coal gasification tank, so all the air discharged from the compressor 2 is transferred to the combustor 3. The supply amount increases, and the pressure loss in the cooling section where the flow path is constricted increases, resulting in a decrease in efficiency.

Further, even if combustion air is supplied at high speed to an oil fuel flow having a relatively low flow velocity from an air passage designed for high-speed fuel flow, efficient and stable combustion cannot be obtained.

Furthermore, since the low calorific value fuel supply system must supply a large amount of fuel to the combustion chamber of the combustor 3, a relatively large diameter low calorific value fuel nozzle opens into the combustion chamber.

Therefore, while operating with high calorific value fuel, there is a risk that combustion gas will flow backwards through the idle low calorific value fuel nozzle, resulting in unstable combustion and a combustion pressure difference between multiple combustors operating in parallel. This causes combustion gases to move between combustors, which is extremely dangerous.

Therefore, a first object of the present invention is to enable efficient combustion of any fuel in a gas turbine combustion system that selectively uses fuels with different calorific values per unit amount. In a gas turbine combustion system in which calcined air is supplied to a combustor to combust fuel and combustion gas is supplied to a gas turbine, a part of the compressed air supplied from the compressor to the combustor is combusted. A branch flow path is provided for extracting air from an upstream part of the cooling air passage of the combustor depending on the type of fuel and returning the extracted air to a position of the combustor with less pressure loss, In the invention, fuel is supplied to a combustor from a fuel supply system capable of supplying multiple types of fuel having different calorific values per unit amount, and compressed air is supplied from a compressor to a combustor to combust the fuel,
In a gas turbine combustion system that supplies combustion gas to a gas turbine, a part of the compressed air discharged from the compressor is extracted according to the type of the fuel to be combusted, and the extracted air is used to supply low calorific value fuel. The present invention is characterized by providing a branch flow path that returns to the combustor via the system.

[Function] The air flow distribution in the combustor changes according to the calorific value per unit amount of fuel to be combusted, and which fuel can be used for coal gasification with low calorific value in the gas turbine combustion system of the combined cycle power generation system. The object of the present invention is to enable a combustor designed to efficiently burn fuel to also efficiently burn high calorific value fuels such as oil or natural gas.

A second object of the present invention is to enable safe combustion of any fuel in a gas turbine combustion system that selectively uses fuels with different calorific values per unit amount. To enable the safe combustion of high calorific value fuels such as oil or natural gas in combustors designed to burn low calorific value coal gasified fuels in gas turbine combustion systems in gasification combined cycle power generation systems. More specifically, the objective is to prevent combustion gas from flowing back into the low calorific value fuel supply system during combustion of high calorific value fuel.

[Means for Solving the Problem] In order to achieve this object, the first invention supplies fuel from a fuel supply system capable of supplying a plurality of types of fuel having different calorific values per unit amount, and also from a compressor. The pressure also burns efficiently.

Further, when high calorific value fuel is burned, extracted air is supplied from the low calorific value fuel supply system to the combustion chamber, so that combustion gas does not flow back into the low calorific value fuel system.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 10.

FIG. 1 shows a combustor section of a gas turbine main body, a fuel supply system, and a return system for oil and air and the extracted air in a coal gasification combined cycle power generation system.

As shown in FIGS. 2 to 5, in the combustor section 3, compressed air discharged from the compressor 2 is supplied into a vehicle interior 312 from an air intake 311 formed in a vehicle exterior frame 310. Cabin 3
12 includes a transition piece 330 coupled to the rear end of the combustor liner 320, and a rear part of the combustor liner 320 and the transition piece 33.
There is a transition pipe cooling flow sleeve 314 located so as to surround the outer periphery of the 0 via an air flow path 313.
The air supplied to the combustor liner 320 flows through the air passage 313 and reaches the combustor outer cylinder chamber 315 on the outer periphery of the combustor liner 320.

Air in the combustor outer cylinder chamber 315 passes through a ventilation hole 341 formed in a liner cooling flow sleeve 340 provided surrounding the outer periphery of the head of the combustor liner 320 and reaches the outer periphery of the head of the combustor liner 320. .

The combustor liner 320 is part of the fuel nozzle assembly 3
50, and forms a combustion chamber 321 therein. A part of the air around the combustor liner 320 passes through a vent hole 322 formed in the peripheral wall of the combustor liner 320 and is supplied to the combustion chamber 321, and another part is supplied to the fuel nozzle assembly 350.
The air is supplied into the combustion chamber 321 from a swirling jet nozzle 352 formed in the nozzle head portion 351 .

The fuel nozzle assembly 350 is shown in FIGS.
As shown in detail in the figure, the nozzle head section 35
An oil fuel supply path 354 and an atomizing air supply path 355 that supply oil and air jetted from an oil fuel jet nozzle 353 formed at the center of The gas is supplied to the gas purification device 10. The gas purifier 10 refines the gas and supplies it to the coal gasification fuel passage 20 , and supplies it to the coal gasification fuel supply passage 358 of the fuel nozzle assembly 350 via the on-off valve 21 and the flow rate regulating valve 22 .

Furthermore, an air flow path 23 is branched from the air flow path 12 downstream of the booster compressor 5, and a part of the pressurized air is transferred to the coal gasified fuel flow through a flow rate adjustment valve 24 and a check valve 25. 20 downstream of the flow regulating valve 22. The upstream side of the flow rate adjustment valve 22 is connected to an inert gas supply device 28 via an on-off valve 27 by an inert gas passage 26 .

In the above configuration, a case where this coal gasification combined cycle power generation system is operated using coal gasification fuel will be explained.

At startup, first, compressed air obtained by driving a compressor directly connected to a turbine by an external drive source is supplied to the air supply 311 and the atomizing air supply path 355.

Then, oil fuel is supplied to the oil fuel supply path 354 to ignite the fuel jetted from the oil fuel jetting nozzle 353, thereby supplying coal gasified fuel with a low calorific value which is spouted swirlingly from several coal gasified fuel jetting nozzles 356 and 357. A coal gasification fuel supply path 358 is provided. In addition, the arrangement of each nozzle in the nozzle head part 351 is as follows: an oil/fuel jet nozzle 353 in the center;
A large number of coal gasified fuel injection nozzles 356 are arranged in an annular manner on the outside, and a large number of air swirling injection nozzles 352 and coal gasified fuel injection nozzles 357 are further arranged in an annular manner on the outside.

Returning to FIG. 1, the vehicle interior 31 is formed on the exterior frame 310 of the vehicle interior.
The air bleed port 316 that opens to the compressor 2 is connected to the compartment 31 from the compressor 2.
A part of the compressed air supplied to the air flow path 12 is extracted and
branch to. A part of the air bled into the air passage 12 is returned to the combustor outer cylinder chamber 315 from the bleed air return port 317 via the air passage 13 and the on-off valve 14. In addition, air flow path 1
The air of No. 2 is pressurized by the booster compressor 5, and is supplied to the coal gasifier 7 via the check valve 18 and the flow rate regulating valve 19.

The coal gasifier 7 reacts this air with the pulverized coal supplied from the coal supply device 9 to generate gas, which is trowel-combusted. When the amount of oil fuel supplied is gradually increased, the rotational speed of the turbine increases and reaches the rated rotational speed. On the other hand, a part of the air extracted from the casing 312 through the bleed port 316 is supplied to the coal gasifier 7 via the boost compressor 5, check valve 18, and flow rate adjustment valve 19 in the air passage 12. Used for coal gasification. Combustion using oil fuel continues until the amount of coal gas generated reaches a predetermined amount.

During this time, a part of the air compressed by the booster compressor 5 is ejected from the air flow path 23 through the flow rate adjustment valve 24 and the check valve 25 from the coal gasification fuel supply path 358 of the fuel nozzle assembly 350. Nozzle 356, 357
and is injected into the combustion chamber 321. Since this ejected air forms a swirling flow of fuel ejected from the oil-fuel ejection nozzle 353, mixing with the fuel ejected from the oil-fuel ejection nozzle 353 is promoted, improving combustion efficiency. Further, combustion gas does not flow back from the coal gasified fuel injection nozzles 356, 357 to the coal gasified fuel supply path 358. From the coal gasification fuel injection nozzle 356°357 to the combustion chamber 32
The flow rate of air ejected into the fuel tank 1 is adjusted by a flow rate regulating valve 24 according to the amount of oil and fuel supplied.

When the amount of coal gasified fuel generated reaches a predetermined amount,
The fuel is switched from oil fuel to coal gasified fuel. In this switching, first, the on-off valve 21 is closed and the on-off valve 27 is closed.
open. Then, the inert gas is supplied from the inert gas supply device 28 while adjusting the flow rate with the flow rate adjustment valve 22,
Air remaining downstream of the coal gasification fuel channel 20 and in the coal gasification fuel supply channel 358 is replaced with the inert gas. Thereafter, the on-off valve 27 is closed and the on-off valve 21 is opened to transfer the coal gasified fuel from the gas purification device 10 to the coal gasified fuel flow path 2.
0 to the coal gasification fuel supply path 358,
The supply of oil fuel to the oil fuel supply path 354 is stopped. A check valve 25 provided in the air flow path 23 prevents inert gas and coal gasified fuel from entering the air flow path 23 .

Incidentally, since the coal gasifier is operated independently using high calorific value fuel, an increase in pressure loss can be prevented without stopping the intake of air into the coal gasifier 7 or reducing the amount of air supplied to the large amount of combustion chamber 321. If the ventilation resistance of this branch flow path is large and a sufficient flow rate cannot be obtained, it is preferable to branch the air flow path 13 from downstream of the boost compressor 5 to obtain a sufficient branch flow rate. Further, this branch flow path can be similarly configured by forming a communication hole in the partition wall between the casing 312 and the combustor outer cylinder chamber 315, and providing an on-off valve in the communication hole. Incidentally, the amount of air extracted from the air bleed port 316 is about 30% of the amount of air supplied to the vehicle compartment 312.

FIG. 6 shows the pressure loss characteristics in this example. In combustion using coal gasified fuel, the total pressure loss rate at the combustor outlet 331 is 1.6%, but if the fuel is switched directly to oil fuel, it becomes 4.5%. However, if an oil/air branch channel is provided to separate the air as in this example,
The total pressure drop is improved to 1.9%.

Figure 7 shows the CO emission concentration during combustion of oil fuel, and Figure 8 shows the CO emission concentration during combustion of coal gasified fuel.
1, the air flow path 313 in the combustor 3
The air flow rate increases and the pressure loss increases. That is, since the combustor liner 320 and transition piece 330 of this type of combustor 3 are heated by radiant heat and convection from the combustion gas,
It is necessary to cool efficiently. For this reason, the combustor liner 320 uses film cooling to form an air layer along its inner wall to reduce the inflow heat, but the transition piece 330 uses impingement cooling, convection cooling, etc. because it is difficult to form a film. Thermal barrier coatings are used to cool or insulate the inner surface. Therefore, the pressure loss in the air flow path 313 is large, especially the loss at the outlet thereof.

In order to prevent an increase in pressure loss in the air flow path 313, in this embodiment, in addition to a branch flow path that returns air extracted from the casing 312 to the combustion chamber 321 via the coal gasification fuel supply system, The extracted air is passed through the air flow path 13 and the on-off valve 1.
4 from the bleed air return port 317 to the combustor outer cylinder chamber 31
A branch flow path is provided to return the flow to No. 5. This shows the combustion chamber. It can be seen that good combustion is obtained with low CO emission concentration within the turbine operating range in any fuel combustion.

FIGS. 9 and 10 are characteristic diagrams showing this in terms of combustion efficiency. FIG. 9 shows the case when oil fuel is burned, and FIG. 10 shows the case when coal gasified fuel is burned. Almost 100 in any combustion
% combustion efficiency.

The control of each of the flow rate adjustment valves and on-off valves described above is automatically performed with reference to electrical signals from the fuel control system and the pressure sensor.

[Effects of the Invention] As described above, the present invention can efficiently burn any fuel by changing the air flow distribution in the combustor according to the calorific value per unit amount of fuel to be combusted. In addition, since extracted air is supplied from the low calorific value fuel supply system to the combustion chamber during high calorific value fuel combustion, combustion gas does not flow back into the low calorific value fuel supply system, making it possible to achieve safe combustion.

Therefore, for example, in a gas turbine combustion system in a coal gasification combined cycle power generation system, a combustor designed to efficiently burn coal gasified fuel with a low calorific value can efficiently and safely burn high calorific value fuels such as oil or natural gas. can be burned.

[Brief explanation of the drawing]

Figures 1 to 10 show an embodiment of the present invention.
Figure 1 is a system diagram showing the combustor section of the gas turbine main body, fuel supply system, extraction air, and return system for the extracted air in a coal gasification combined cycle power generation system, and Figure 2 is a longitudinal section around the combustion chamber in the combustor. A perspective view, FIG. 3 is a vertical perspective view of the nozzle head, FIG. 4 is an mV-IV sectional side view of FIG. 3, FIG. 5 is a front view of the nozzle head, and FIG. 6 is a pressure loss characteristic of the combustor. Figures 7 and 8 are CO emission concentration characteristic diagrams, Figures 9 and 10 are combustion efficiency characteristic diagrams, and Figure 11 shows conventional fuels such as oil fuel, which is a high calorific value fuel, and low calorific value fuel. 1 is a system diagram of a gas turbine combustion system in a coal gasification combined cycle power generation system that uses coal gasification fuel as fuel. 3... Combustor, 7... Coal gasification furnace,
12゜13...Air flow path, 10...Gas purification device, 14...Opening/closing valve, 20...
- Coal gasification fuel flow path, 26... Inert gas flow path, 28... Inert gas supply device, 310...
....Vehicle compartment outer frame, 311...Air inlet, 31
2... Vehicle interior, 313... Air flow path, 3
14...Flow sleeve for tail tube cooling, 315.
...Combustor outer cylinder chamber, alg...Air bleed port,
317... Bleed air return) A 320... Combustor liner, 321... Combustion chamber, 330...
... Transition tube, 350 ... Fuel nozzle assembly, 351 ... Nozzle head section, 352 ...
... Air swirl jet nozzle, 353 ... Oil fuel jet nozzle, 354 ... Oil fuel supply path, 355
...Eruption air supply channel, 356,357...
... Coal gasification fuel injection nozzle, 358 ... Coal gasification fuel supply path. Fig. 6 31I 3/3/l outlet 33/ Fig. 7 Gas turbine load (%) Fig. 8 Caster L gong 1 3/3/l exit 33/ Fig. 8

Claims (1)

[Scope of Claims] 1. The fuel is combusted by supplying fuel from a fuel supply system capable of supplying multiple types of fuel with different calorific values per unit amount and compressed air from a compressor to a combustor, respectively; In a gas turbine combustion system that supplies combustion gas to a gas turbine, a portion of the compressed air supplied from the compressor to the combustor is placed upstream of the cooling air passage of the combustor depending on the type of the fuel to be combusted. A gas turbine combustion system, characterized in that a branch flow path is provided for extracting air from the combustor and returning the extracted air to a position of the combustor with less pressure loss. 2. The gas turbine combustion system according to claim 1, wherein the branch flow path is provided with a pressurizing means for pressurizing the air flowing through the flow path. 3. The gas turbine combustion system according to claim 1 or 2, wherein the branch flow path is provided with a backflow prevention means. 4. In claim 1, the fuel supply system includes a fuel supply system that supplies coal gasification fuel and a fuel supply system that supplies fuel that has a higher calorific value per unit amount than the coal gasification fuel. The branch flow path bleeds a portion of the compressed air supplied from the compressor to the combustor from an upstream portion of the cooling air passage of the combustor when the fuel supply system supplies fuel with a large calorific value. , A gas turbine combustion system characterized in that the extracted air is returned to a position in the combustor where pressure loss is low. 5. In one of claims 1 to 4, the branch flow path is characterized in that the bleed air is returned to the combustor via a low calorific value fuel supply system. Gas turbine combustion system. 6. Claim 5, further comprising an inert gas supply system that supplies inert gas to a region of the low calorific value fuel supply system through which the bleed air passes, and where fuel and air are mixed in the region. 1. A gas turbine combustion system, comprising: control means for controlling the supply of fuel, air, and inert gas to the region to prevent 7. The gas turbine combustion system according to claim 6, wherein the control means supplies inert gas to the region before supplying the low calorific value fuel. 8. Fuel is supplied from a fuel supply system that can supply multiple types of fuel with different calorific values per unit amount, and compressed air is supplied from a compressor to a combustor, the fuel is combusted, and the combustion gas is sent to a gas turbine. In the gas turbine combustion system, a part of the compressed air discharged from the compressor is extracted depending on the type of the fuel to be combusted, and the extracted air is supplied to the combustion source via a low calorific value fuel supply system. A gas turbine combustion system characterized by having a branch flow path returning to the vessel. 9. Claim 8, wherein the combustor includes a high calorific value fuel nozzle that injects high calorific value fuel into a combustion chamber;
A low calorific value fuel nozzle arranged around the outer periphery of the high calorific value fuel nozzle and injecting low calorific value fuel into the combustion chamber; and an air nozzle arranged around the outer periphery of these fuel nozzles and injecting combustion air into the combustion chamber. A gas turbine combustion system comprising: 10. The gas turbine combustion system according to claim 8 or 9, wherein the branch flow path is provided with a pressurizing means for pressurizing the air flowing through the flow path. 11.Claim 8 or 9 or 10
2. The gas turbine combustion system according to item 1, wherein the branch flow path is provided with a backflow prevention means. 12. In claim 8, the fuel supply system includes a low calorific value fuel supply system that supplies coal gasified fuel and a high calorific value fuel supply system that supplies fuel that has a higher calorific value per unit amount than the coal gasified fuel. and a calorific value fuel supply system, and the branch flow path is characterized in that when the fuel supply system supplies fuel with a large calorific value, the extracted air is returned to the combustor via a low calorific value fuel supply system. Gas turbine combustion system. 13. In one of claims 8 to 12, an inert gas supply system that supplies an inert gas to a region of the low calorific value fuel supply system through which the bleed air passes; A gas turbine combustion system comprising a control means for controlling the supply of fuel, air, and inert gas to the region so that the fuel and air do not mix in the region. 14. The gas turbine combustion system according to claim 13, wherein the control means supplies inert gas to the region before supplying the low calorific value fuel.