JP3110558B2 - Combustor combustion method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of combustion combustor to reduce the concentration of nitrogen oxides in the exhaust gas (NO _X).

[0002]

In recent years, in consideration of environmental, although release into the atmosphere of nitrogen oxides generated by combustion (NO _X) is a major problem, conventional combustion device for a natural gas NO _X discharged from a so-called thermal NO _X which nitrogen in the air are oxidized in the high temperature region.

[0003] Considering a gas turbine combustor as one of the combustion devices, a conventional combustion combustor of this type employs diffusion combustion capable of obtaining stable combustion.
The combustion of the fuel / air mixture produces an adiabatic flame temperature of around 2000 ° C. This high-temperature combustion gas is mixed with the air to lower the temperature, NO _X amount unacceptable for the surface of the diffusion flame is high temperature is generated. However, since the generation of the thermal NO _X increases exponentially with the rise in temperature, the NO _X generation can be greatly reduced by slightly lowering the temperature of the combustion flame. As one of effective means for lowering the temperature of a combustion flame, a premixed combustion method in which fuel and combustion air are mixed before combustion and burned as a lean mixed gas is known.

[0004] However, in premixed combustion in which air of a constant edge is supplied, such as a combustor of a gas turbine engine,
When you adjust trying to achieve a complete combustion and NO _X in the vicinity of the rated, unburnt blow-off of the rapid increase and flame is generated in lowering the load.

[0005] The inventors of the present invention have proposed in Japanese Patent Application No. Hei.
No. 75, a combustion gas injection hole for ignition is provided in the center, and an injection hole for primary combustion mixed gas in which the mixing ratio of air and fuel gas is constant around the hole; And a combustion device having concentrically provided a secondary combustion mixed gas ejection hole having a variable mixing ratio with
Using this combustion device, at the time of startup, while igniting fuel gas is ejected from the ignition fuel gas ejection hole and burned,
A mixed gas of air and primary fuel gas is ejected from the primary combustion mixed gas ejection hole and burned, and after starting, air having a composition ratio corresponding to the load and secondary air are mixed from the secondary combustion mixed gas ejection hole. The present invention provides a combustion method in which a mixed gas with a fuel gas is ejected and burned, and then a fuel gas for ignition is narrowed down, and the mixed gas for primary combustion is supplied at a constant rate to continue the combustion.

[0006]

The combustion device and combustion method of the structure ## 0006], shown in the pre-mix combustion air for combustion is a certain amount supplied, together low emissions of exhaust and unburned components of the NO _X If it was possible to extend the range increases, which were both suppressed combustion emissions emissions and unburned components of the maximum load during the NO _X in the combustion device (CO), 6
As shown by A, the air ratio of the primary combustion mixed gas is set to 1.5.
In the case of a high air ratio as described above, if the load is reduced, a large amount of unburned components will be discharged at a certain load factor a or lower, and the efficiency of the combustor will be reduced. When the set mixing ratio of the primary combustion mixed gas is changed to a low air ratio (for example, 1.3) in order to widen the load range from the maximum load to the start of discharge of unburned components, B in FIG. low NO _X performance is impaired emissions of the NO _X in the vicinity at the highest load will be increased as shown.

In both cases A and B, if such a load range that can be operated with low NO _X and low unburned components is obtained,
Normal combustion equipment that controls both fuel gas and air according to the load does not cause much problem, but it is not sufficient for special applications that burn with a fixed amount of air, such as a gas turbine engine combustor. The efficiency of the system decreases.

[0008] The present invention has been made in view of the above problems, and an object thereof is unburned components from the maximum load while maintaining low NO _X performance (CO) extending the load range up begins to discharge.

[0009]

An outer container and an inner container are provided, and an air inlet through which air is supplied from the outside is formed between the outer container and the inner container. An ignition fuel gas ejection hole is provided, and the fuel gas ejection hole is provided around the ignition fuel gas ejection hole, and the fuel gas is ejected when air flows in from the air introduction port. A primary combustion premixed gas ejection hole for ejecting a primary combustion premixed gas premixed with water is provided concentrically, and further communicates with the air inlet, and a load is applied when air flows in from the air inlet. The supply amount of the fuel gas is controlled in accordance with the pressure, and the fuel gas is blown out, and the premixed gas for secondary combustion in which the air and the fuel gas are mixed in advance and the mixing ratio is variable is blown out.
The secondary combustion premixed gas ejection hole is provided concentrically on the outer periphery of the primary combustion premixed gas ejection hole in the same ejection direction as the primary combustion premixed gas ejection hole and across a partition wall. The fuel gas for ignition is ejected from the fuel gas ejection hole and burned, and at the same time, the mixing ratio of air and fuel gas whose air inflow is constant by the shape of the combustion device stabilizes the flame in the combustion chamber. The primary combustion premixed gas having a mixing ratio necessary to maintain the primary combustion premixed gas is ejected from the primary combustion premixed gas ejection hole and burned, and after the primary combustion premixed gas is ignited, the ignition fuel The supply of gas is stopped or reduced as necessary, and then the premixed gas for secondary combustion is composed of fuel gas that increases or decreases according to the load and air whose inflow is constant depending on the shape of the combustion device regardless of the load. Ejection from the secondary combustion premixed gas injection hole The fuel is burned, and then the ratio of the fuel gas in the mixed gas for secondary combustion is controlled in accordance with the fluctuation of the load. The flame of the premixed gas for primary combustion acts as a pilot flame to perform premixing for secondary combustion. In the combustion method in the combustor configured to burn integrally with the gas, the injection amount of the fuel gas of the primary combustion premixed gas and the emission amount of the primary combustion premixed gas are set so that the emission amount of NOx is minimized at the time of the maximum load. When the amount of fuel gas of the secondary combustion premixed gas and the amount of fuel gas to be injected are set and burned, when the load reaches a predetermined value or less, the fuel gas in the primary combustion premixed gas is increased by a predetermined amount. At the same time, the fuel gas in the secondary combustion premixed gas is reduced by a predetermined amount.

[0010]

[Action] it is possible to widen the flammable range exhibiting such both low discharge of emissions and unburned components of the NO _X control only the supply amount of the simple fuel gas according to the combustion method.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is an axial sectional view of one embodiment of a gas turbine combustor to which the present invention is applied, and FIG. 2 is an end view of the combustor.

In the combustor, a combustion gas ejection block 10 is supported at a position (left side in the figure) of the inside of a flanged cylinder 100 in the axial direction substantially at the center thereof, and is connected to the combustion gas ejection block 10 to form a combustion cylinder 20. Is arranged and the combustion cylinder 2
0 forms a combustion chamber 20a.

As can be clearly understood from FIG. 2, an ignition fuel gas ejection hole 1 is formed at the center of the combustion gas ejection block 10, and an annular primary combustion mixed gas ejection hole 2 is formed therearound.
Are formed, and an annular mixed gas ejection hole for secondary combustion 3 is formed around the periphery thereof. Partition walls of the mixed gas ejection hole 2 for primary combustion and the mixed gas ejection hole 3 for secondary combustion are respectively provided on the partition walls. A collar 4 is provided to prevent the flame formed in the nozzle hole from affecting each other at its root. The flange 4 forms a small combustion space S in front of the primary combustion mixed gas ejection hole 2.

An ignition fuel gas is supplied to the ignition fuel gas ejection hole 1 via a conduit 11, and a primary fuel gas is ejected from the tip of the conduit 12 to a primary combustion mixed gas ejection hole 2. The secondary fuel gas is jetted from the tip of the conduit 13 to the mixed gas jetting hole 3 for the next combustion. Swirlers (swirlers) 14 and 15 are attached to the opposite ends of the primary and secondary combustion mixed gas discharge holes 2 and 3 from the discharge ends.

On the other hand, an air inlet 100a is formed at the rear (right side in the figure) of the cylindrical body 100, from which combustion air is supplied. Also, the ends of the primary and secondary combustion mixed gas injection holes 2 and 3 opposite to the injection ends communicate with the inside of the cylindrical body 100 via the swirlers 14 and 15, and air can be introduced. It has become.

Near the rear end of the fuel cylinder 20, cooling air for diluting the combustion exhaust gas discharged from the combustion cylinder 20 and lowering the temperature to a temperature suitable for a turbine (not shown) connected to the next stage is provided. An air hole 5 for blowing is provided.

FIG. 3 is a block diagram of a combustion control circuit of the combustor having the above configuration.

In the drawing, reference numeral 30 denotes a combustor according to the present invention shown in FIG. 1, reference numeral 41 denotes an adjusting valve for adjusting a supply amount of an ignition fuel gas supplied to the combustor 30, and reference numeral 42 denotes a supply of a primary fuel gas. An adjusting valve for adjusting the amount, an adjusting valve 43 for adjusting the supply amount of the secondary fuel gas, a compressor 50 for supplying a substantially constant amount of compressed air to the combustor 30, and a combustion exhaust gas 51 from the combustor 30. The turbine to be operated, 60 is the turbine 5
1, a load such as a generator driven by 1; 61, an output detector for detecting the output of the load (for example, the amount of generated power when the load is a generator); 70, a gas based on the output of the output detector 61; It is a controller that determines the supply amount and controls the opening of the regulating valves 42 and 43 to adjust the gas supply amount to the combustor 30.

Next, the combustion control by the combustion control circuit shown in FIG. 3 will be described with reference to FIG.

First, at the time of startup, the regulating valve 41 is adjusted to supply the ignition fuel gas from the conduit 11 to the ignition fuel gas ejection hole 1 to cause diffusion combustion. The flame from the ejection hole 1 plays a role of stably igniting and burning the premixed combustion flame generated by the primary fuel gas thereafter. Next, a fixed amount of primary fuel gas is supplied from the conduit 12 and supplied to the primary combustion mixed gas outlet 2 at an air ratio of about 1.3 to stably burn. The supply of the secondary fuel gas to the gas ejection holes 3 is started, and premix combustion is performed. Since the premixed flame acts like a pilot flame by the primary fuel gas and promotes the combustion of the premixed flame by the secondary fuel gas, the flow rate of the ignition fuel gas is reduced or the supply is stopped at this point. Thereafter, the required amount of combustion is obtained by gradually increasing the supply amount of the secondary fuel gas.

When the combustion exhaust gas generated in the combustor 30 and discharged to the rear is supplied to the turbine 51, the power is generated by a generator 60 as a load and supplied to an electric load (not shown). The power generation amount is thus detected. The controller 70 monitors the output of the output detector 61, and determines from the output that the engine load factor is a predetermined value C.
%, The opening degree of the regulating valve 42 is decreased and thereafter kept constant irrespective of the size of the load, and the opening degree of the regulating valve 43 is increased and thereafter changed according to the load. As a result, the supply amount of the primary fuel gas is reduced by a certain amount (for example, about 87% of the previous amount), and the supply amount of the secondary fuel gas is increased by a certain amount (for example, the previous 114%).
%). The engine load factor C at the time of switching the supply amount of the primary fuel gas and the secondary fuel gas can be determined according to the structure of the combustor and the type of the fuel gas. Has proven to be suitable.

[0023] FIGS. 5 (a) and (b) the emissions of emissions and unburned components of the NO _X on the basis of the results obtained by experiments of the present inventors showed in comparison with the conventional combustion method It is a performance comparison figure.

As can be seen, the engine load factor is 1
In the range from 00% to the predetermined value C, the conventional low N
O _X performance is maintained, the discharge significantly suppressed as compared with the conventional the unburned component (Co) while suppressing the slight increase emissions of the NO _X in the range from the load factor C to d, NO
_The combustion range in which both the emission of _{X and} the emission of unburned components can be suppressed to low values has been widened from conventional (a-b) to (ad).

The dashed line shown in the figure, typical NO _X emissions conventional diffusion combustion type gas turbine combustor (300Pp
m (O ₂ % conversion)). According to experiments, when the supply amount of the primary fuel gas has increased by 15% in the range predetermined load factor C, a range satisfying the low NO _X and low unburned resistance (to d) is conventional range It was confirmed that (a-b) was increased by 60%.

[0026] In the above embodiment, the primary fuel gas and secondary fuel gas is switched to the gas supply amount is once, may be a plurality of times, whereby NO _X emissions increase and the unburned components low NO _X and combustion range of the low unburned component can be further reduced increase can be further widened.

[0027]

As described above, according to the present invention, the supply amount of the primary fuel gas is increased by a certain amount and the supply amount of the secondary fuel gas is decreased by a certain amount at a predetermined load factor or less. Therefore, it is possible to maintain the low NO _X property at the time of high load, suppress the increase of the NO _X emission amount at the time of low load, and widen the combustion range in which the emission of unburned components does not occur. According to the present invention, only by controlling the supply amount of the fuel gas, low NO _X and the low unburned component can be extended combustible range, or change the structure of the combustor Therefore, another device There is no need to add

[Brief description of the drawings]

FIG. 1 is an axial view of an embodiment of a combustor to which a combustion method according to the present invention is applied.

FIG. 2 is an end view of the combustor shown in FIG. 1;

FIG. 3 is a block diagram of a fuel control circuit that implements the combustion method according to the present invention.

FIG. 4 shows a change in fuel gas supply amount with respect to a load change in the fuel method according to the present invention.

FIG. 5 is a diagram showing NO _X emissions and unburned component emissions in a combustion method according to the present invention in comparison with a conventional combustion method.

6 is a diagram showing the relative NO _X emissions and (b) the engine load factor to unburned components for (a) an engine load factor for explaining the combustion circuit by conventional combustion control method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ignition fuel gas ejection hole 2 Primary combustion mixed gas ejection hole 3 Secondary combustion mixed gas ejection hole 5 Premixing pipe 11, 12, 13 Pipe 20 Combustion cylinder 20a Combustion chamber 30 Combustor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-124522 (JP, A) JP-A-3-175211 (JP, A) JP-A-61-179914 (JP, A) JP-A-59-1979 202324 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02C 9/28 F23R 3/28 F23R 3/34

Claims (1)

(57) [Claims] 1. An outer container comprising an outer container and an inner container.
Air that is supplied externally between the vessel and the inner container
An ignition port is formed at the center of the inner container.
A gas outlet is provided and communicates with the air inlet around the fuel gas outlet for ignition.
And the fuel gas is supplied when air flows in from the air inlet.
For primary combustion in which air and the fuel gas are premixed
Premixed gas injection holes for primary combustion to eject premixed gas
Provided concentrically, further communicating with the air inlet, and from the air inlet.
Controls the supply of fuel gas according to the load when air flows in.
And the air and fuel gas are premixed and
Inject premixed gas for secondary combustion with variable mixing ratio
The secondary combustion premixed gas outlet is connected to the primary combustion premixed gas.
The primary direction in the same jet direction as the
A fuel gas for ignition is ejected from the fuel gas ejection hole for ignition , provided concentrically around the periphery of the combustion premixed gas ejection hole.
And burn, and at the same time, the inflow
Is constant, and the mixing ratio of air and fuel gas is combustion
Primary mixing ratio required to maintain stable flame in the chamber
The premixed gas for combustion is discharged from the premixed gas injection hole for primary combustion.
And ignited the premixed gas for primary combustion
After that, the supply of the ignition fuel gas may be stopped if necessary.
Fuel gas, which decreases and then increases or decreases according to the load.
Air whose inflow is constant depending on the combustion device shape regardless of the load
The premixed gas for secondary combustion is composed of
The gas is blown out from the gas outlet and burned, and then the load fluctuates.
Controls the ratio of fuel gas in the secondary combustion mixed gas according to
The flame of the premixed gas for primary combustion is
Acts as a flame and is integrated with the premixed gas for secondary combustion
Combustion method in a combustor configured to burn
Te, so that emissions of NOx becomes the lowest at the time of maximum load
Next, the injection amount of fuel gas of the premixed gas for primary combustion and
And the amount of fuel gas injected from the premixed gas for secondary combustion
When the load reaches the specified value or less
Increases the fuel gas in the primary combustion premixed gas by a predetermined amount.
And the fuel in the secondary combustion premixed gas.
A method for burning a combustor, comprising reducing a predetermined amount of gas .