JPH04124520A - Gas turbine combustor - Google Patents

Abstract

(57) [Summary] 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 fuel-air ratio control structure in a gas turbine combustor.

[Conventional technology]

An example of a combustor that controls the flow rate of air supplied to the inner cylinder is disclosed in Japanese Patent Application Laid-Open No. 63-217141, and a schematic diagram thereof is shown in FIG. The fuel from the fuel nozzle 104 and the air from the air hole 116 are mixed in the premixing chamber 114 to form a premixture, which is then combusted in the combustion chamber 115, so that the fuel-air ratio remains constant even when the fuel flow rate changes. A flow rate control valve 106 is provided in the air hole 116 in order to keep the amount approximately constant. Therefore, at partial load when the amount of fuel supplied to the fuel nozzle 104 is small, the air flow rate required to form a combustible premixture decreases, so the flow rate control valve 106 is throttled to reduce the passage area of the air hole 116. In this structure, the total area of the inner cylinder air holes is maximum at rated load, and reaches the maximum /J1 at low load when fuel nozzle 104 starts supplying fuel. Nitrogen oxides (
No. c) Fuel nozzle 10 to reduce the emission concentration of
If the ratio of fuel flow from fuel nozzle 3 is decreased and the ratio of fuel flow from fuel nozzle 104 is increased, the area ratio of air hole 116 to the total area of the inner cylinder air hole increases, and the passage area of air hole 116 increases at low load. When , decreases, the change in the total area of the inner cylinder air holes also increases, and the air inflow speed into the inner cylinder increases.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into account the fact that the combustor pressure loss increases when the gas turbine is under low load, and there is a problem in that the overall thermal efficiency under low load is significantly reduced.

An object of the present invention is to provide a gas turbine combustor that reduces NOx emission concentration and reduces pressure loss at low loads.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a flow rate control valve for air for forming a premixture with fuel, and.

A plurality of fuel nozzles that supply fuel are divided into multiple groups and each is provided with a fuel supply system, so that the number of supply systems that supply fuel, the fuel flow rate, and the air flow rate for forming a premixture can be controlled according to the load. did.

[Effect]

The fuel flow control valves provided in the plurality of fuel supply systems supply a total fuel flow rate according to the load, select a system that supplies fuel and a system that does not supply fuel, and control the fuel flow rate of each system. An air flow control valve at the inlet of the premixing chamber controls the air flow rate supplied to the premixing chamber. As a result, when the load is high, the fuel flow rate corresponding to the load can be flowed through all the fuel nozzles, and the flow rate ratio of fuel and air can be maintained at a predetermined value.

When the load is low, some fuel nozzles are used to flow the fuel at a flow rate corresponding to the load, so the overall flow rate is small.

Fuel nozzle - The actual fuel flow rate decreases at a small rate.The air supplied to the premixer also flows to the part that is not being supplied with fuel, so at low loads, the fuel and air in the part that is being supplied with fuel is reduced. The air flow rate flowing to maintain the flow rate ratio at a predetermined value decreases at a smaller rate than the air flow rate during high load.

When an air flow control valve is installed downstream of the inner cylinder or in the transition cylinder, a portion of the air supplied to the entire inner cylinder is bypassed depending on the load, mixed with combustion gas, and then flowed to the turbine. This controls the flow rate of air supplied to the premixer. Fuel is controlled in the same way as above, and the amount of air that needs to flow as a bypass in order to maintain the fuel-to-air flow rate ratio in the fuel supplying part at a predetermined value during low load is small compared to the overall air flow rate. It becomes a percentage.

When an air flow control valve is installed at the connection between the outer cylinder and the external low-pressure part of the combustor, a portion of the air supplied to the entire inner cylinder is bypassed and released outside the combustor, thereby improving premixing. Controls the flow rate of air supplied to the device. The fuel is controlled the same as above, and at low loads, the air flow rate that needs to be released through the flow control valve to maintain the fuel to air flow rate ratio of the fueled section at a predetermined value is the total air flow rate. It is a small percentage of the flow rate.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Air compressed by a compressor having guide vanes at the inlet that can control the flow rate of intake air flows through a passage 120 formed by the outer cylinder 102 and the inner cylinder 101 in the direction of the arrow 201.

In addition to cooling air holes (not shown), the inner cylinder lot has an air hole 108 for a pilot burner. Air hole 10 for main burner
7゜109, 110, 122 are provided, air hole 107゜1
22 communicates with a passageway 120 via an air hole 116 with a flow control valve 106.

At the center of the interior is a fuel nozzle 103 that supplies fuel for the pilot burner, and around its outer periphery are three main burners 104 and 105 for premix combustion. 111. Fuel supply system 112 to fuel nozzle 104. The fuel supply systems 11 and T to the fuel nozzle 105 are each provided with a fuel control valve (not shown).

The fuel supplied from the fuel nozzle 103 into the inner cylinder 101 burns in the combustion chamber 115 while swirling and mixing with the air flowing in from the air hole 108 .

On the other hand, the fuel supplied from the fuel nozzle 104 into the premixing chamber 114 is mixed with air that swirls and flows in from the air hole 109 and air that flows in from the air hole 107 via the air hole 116 having the flow rate control valve 106. The mixture becomes a combustible premixture, which is combusted in the 1M combustion chamber 115. fuel nozzle 1
The fuel supplied from 05 to the inside of the premixing chamber 119 swirls and flows through the air hole 110 and flows into the flow control valve 106.
It mixes with the air flowing in from the air hole 122 via the air hole 116 having a combustible premixture.

It burns in the combustion chamber 115.

The fuel distribution for each output of this combustor is shown in FIG. 3, and the air distribution is shown in FIG. 4. From startup ignition with an output of 0% or less to self-sustaining operation and rated rotation speed operation, fuel is supplied from the fuel nozzle 103 of the pilot burner and burned in the combustion chamber 115. Fuel is not supplied from the fuel nozzles 104 and 105, and the same is true from 0% to 8% of the output. Fuel is supplied only from the fuel nozzle 103, and the 6th output a, indicated by P in FIG. 3, is the same. % and b%, the fuel is supplied from the fuel nozzle 103 of the pilot burner and at the same time, it is also supplied from the fuel nozzle 104 of the main burner, and the fuel flow rate of the fuel nozzle 104 is indicated by M-1. 8 power b%
In the above description, fuel is supplied from all the fuel nozzles, and the fuel flow rate from the fuel nozzle 105 is indicated by M-2. As for air distribution, as shown in Fig. 4, the flow rate from the air hole 108 that supplies the pilot burner is indicated by P, and the air flow rate from the air holes 107 and 109 that supplies the main burner is indicated by M-1.
Air holes 110, 1 shown in and supplied to other main burners
The air flow rate from No. 22 is shown as M-2, and the air flow rate for cooling the inner cylinder wall surface is shown as C. When the output is less than a%, the air flow control valve 106 is operated in the closing direction as the output increases so that the pilot burner can perform stable and highly efficient combustion, thereby reducing the area of the air holes 116 and reducing the overall area of the air holes. .

By relatively increasing the proportion of P and decreasing the proportion of M, at output a%, M-1, which is a part of the main burner, has a fuel-air ratio that allows premix combustion, and the pilot burner is also stable. The air flow rate and fuel flow rate are controlled to maintain a fuel-air ratio that allows combustion. Note that only air flows in the premixer 119, and no fuel flows. At an output of b% or higher, fuel is also flowed through the fuel nozzle 105 so that premix combustion is possible even in the main burner M-2, and the air flow control valve is set so that all the main burners have a fuel-air ratio that allows premix combustion. 1
Operate 06.

According to this embodiment, operation based on premixed low-temperature combustion with low NOx emission concentration is possible in the output range of a% or more, and in particular, the fuel flow rate of the pilot burner can be reduced in the output range of 8% or more. By using the remaining fuel, constant premixed low-temperature combustion is possible, so there is little change in NOx emission concentration, and the fuel supply system for the main burner for premixed combustion is reduced at low output. The rate of change in air flow rate required for premix combustion has been reduced, combustor pressure loss at low output has been reduced, and reductions in thermal efficiency have been reduced.

Note that the present invention is effective for gas fuel and liquid fuel.

FIG. 6 shows an example in which the air flow control valve 121 is provided in the transition piece 116. FIG. 7 shows a cross section taken along line 1--2 in FIG. 6. Air that does not participate in combustion at low load is bypassed through the air hole 120 between the downstream part of the inner cylinder 101 where the combustion reaction is completed and the exit of the transition piece 116, and mixes with the combustion gas.
The same amount of combustion gas as in the structure shown in FIG. 1 is supplied to the six-outlet turbine. The fuel distribution for each output of this combustor is shown in FIG. 8, and the air distribution is shown in FIG. 9. When the output is below a%, fuel is supplied only from the fuel nozzle 103, and in the range of 0-order output a% and b%, which is indicated by P in FIG. The fuel is also supplied from the fuel nozzle 104, and the fuel flow rate from the fuel nozzle 104 is indicated by M-1. At an output of b% or higher, fuel is supplied from all fuel nozzles, and the fuel flow rate from the fuel nozzle 105 is indicated by M-2.

Air distribution is 9th r! ! As shown in I, the flow rate from the air hole 108 supplied to the pilot burner is indicated by P, and the flow rate of air from the air holes 107 to 109 supplied to the main burner is indicated by M-1, which is supplied to the other main burners. The air flow rate from the air holes 110 and 122 is indicated by M-2, the inner cylinder wall surface cooling air flow rate is indicated by C, and the bypass air flow rate from the air hole 120 is indicated by B. When the output is less than a%, the air flow rate control valve 121 is closed and the bypass air from the air hole 120 is zero. When the output reaches a%, the air flow rate and the fuel flow rate are controlled so that M-1, which is a part of the main burner, can perform premix combustion, and the pilot burner also maintains a fuel-air ratio that allows stable combustion. In addition, the premixer 11
Only air is flowing inside 9, not fuel. At an output of b% or more, fuel is also flowed through the fuel nozzle 105 so that premix combustion is possible in the main burner M-2, and the air flow control valve is set so that all the main burners have a fuel-air ratio that allows premix low-temperature combustion. Operate 121.

According to this embodiment, operation based on premixed low-temperature combustion with low NOx emission concentration is possible in the output range of output a% or higher, and in particular, in the output range of output b% or higher, the pilot burner fuel flow rate can be reduced. Since the remaining fuel can be premixed and burned at a low temperature in a nearly constant manner, there is little change in the NOx emission concentration. In addition, by reducing the fuel supply system of the main burner for premix combustion at low output, the rate of change in air flow rate required for premix combustion is reduced, and the decrease in combustor pressure loss at low output is small. This made it possible to prevent a rise in the wall surface temperature of the upstream portion of the inner cylinder. Note that the present invention is also effective for gas fuel and liquid fuel.

〔Effect of the invention〕

According to the present invention, from low load to high load, the rate of change in air flow rate is reduced and NO is mainly used for premixed low temperature combustion.
Since it is possible to achieve operation with low x emission concentration,
It is possible to reduce the increase in combustor pressure loss during low load and to reduce the decrease in thermal efficiency.

In addition, when air unnecessary for combustion is bypassed, it is possible to reduce the rate of change in air flow rate from low to high loads and achieve operation with low NOx emission concentration mainly based on premixed low-temperature combustion. .

It is possible to reduce the decrease in combustor pressure loss during low load and to reduce the rise in wall surface temperature at the upstream portion of the inner cylinder.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the continuous burner section of an embodiment of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, Fig. 3 is a detailed explanatory view of the present invention, and Fig. 4 is Detailed explanatory diagrams of the present invention, FIG. 5 is a sectional view of a combustor part of a conventional example, FIG. 6 is a sectional view of a combustor part of a second embodiment of the present invention, and FIG. 7 is a - ■ Line cross section, No. 8
FIG. 9 is an explanatory diagram of fuel distribution according to a modification of the present invention, and FIG. 9 is an explanatory diagram of air distribution according to a modification of the present invention. 101... Inner cylinder, 102... Outer cylinder, 103... Fuel nozzle, 104... Fuel nozzle, 105... Fuel nozzle, 106... Air flow control valve, 114... Premixing Container, 116... Tail piece, 119... Premixing chamber, 1
21... Air flow control valve. Figure Figure Figure Figure Figure 6 Figure 18 Figure 9

Claims (1)

[Claims] 1. An inner cylinder that mixes and burns high-pressure air from a compressor and fuel supplied from a separate system in its internal space, and a fuel nozzle that supplies fuel into the inner cylinder; In a gas turbine combustor that includes a transition pipe that guides combustion gas generated in the inner cylinder to a downstream turbine and an outer cylinder that houses these, an air flow rate control valve for forming a premixture with the fuel is provided. A fuel nozzle provided at the entrance of the inner cylinder flow path and supplying fuel for forming a premixture with air is divided into a plurality of groups, and a supply system having a fuel flow rate control mechanism is provided for each group, A gas turbine combustor characterized in that it is possible to supply and stop fuel supply to the fuel nozzle and to control the fuel-air ratio. 2. The gas turbine combustor according to claim 1, wherein the air flow rate control valve is provided downstream of the inner cylinder or in the transition piece. 3. The gas turbine combustor according to claim 1, wherein the air flow control valve is provided at a connecting portion between the outer cylinder and the external low pressure section of the combustor section.