JP2016191507A - Combustion device, gas turbine and power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a nitrogen oxide (NOx) contained in a combustion exhaust gas discharged from a combustor more than before.SOLUTION: The combustion device includes: a predetermined fuel supply part; the combustor for combusting the fuel supplied from the fuel supply part using combustion air; a reductant supply part for supplying a predetermined reductant to the combustor; and a catalyst reduction part for receiving the combustion exhaust gas supplied from the combustor and removing the nitrogen oxide contained in the combustion exhaust gas using a reduction catalyst. The combustor includes: a combustion region for combusting the fuel; and a reduction region for reducing the nitrogen oxide generated in the combustion region using the reductant.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a combustion apparatus, a gas turbine, and a power generation apparatus.

  Patent Document 1 listed below describes a technique for reducing NOx (nitrogen oxide) contained in exhaust gas from a diesel engine or the like using a catalyst in the presence of ammonia gas. This technology reduces NOx (nitrogen oxide) using a reduction catalyst containing platinum and palladium in the presence of ammonia gas, and an aqueous urea solution upstream of the reduction catalyst with respect to exhaust gas exhausted from the engine By spraying, ammonia gas is directly generated in the exhaust pipe.

Special table 2010-519025 gazette

  By the way, in the said prior art, since urea aqueous solution is sprayed in a position comparatively close to a reduction catalyst in an exhaust pipe, the distance (mixing distance) for mixing ammonia gas with combustion exhaust gas cannot fully be ensured. That is, it is difficult to sufficiently (equally) mix ammonia gas with NOx before contacting with the reduction catalyst. Therefore, in the above-described conventional technology, a region where the reducing agent is concentrated or a region where the reducing agent is thick is generated. There is a problem that it cannot be reduced. In order to reduce the burden on the reduction catalyst, it is desirable to reduce nitrogen oxide (NOx) in the combustion exhaust gas discharged from the combustor as much as possible.

  This invention is made | formed in view of the situation mentioned above, and aims at reducing nitrogen oxide (NOx) in the combustion exhaust gas discharged | emitted from a combustor rather than before.

  In order to achieve the above object, according to the present invention, as a first solution means for a combustion apparatus, a predetermined fuel supply unit and a combustor that burns fuel supplied from the fuel supply unit using combustion air A reducing agent supply unit that supplies a predetermined reducing agent to the combustor; a catalyst reducing unit that receives the combustion exhaust gas supplied from the combustor and removes nitrogen oxides in the combustion exhaust gas using a reduction catalyst; And a combustor includes a combustion region in which fuel is combusted and a reduction region in which nitrogen oxides generated in the combustion region are reduced with a reducing agent.

  In the present invention, as a second solving means relating to the combustion apparatus, in the first solving means, a means is provided in which the fuel supply unit supplies natural gas and ammonia as fuel to the combustor.

  In the present invention, as a third solving means relating to the combustion apparatus, in the second solving means, the fuel supply unit is provided in the combustor so that a stoichiometric ratio of natural gas and ammonia to the combustion air is obtained. The means of supplying is adopted.

  In the present invention, as a fourth solving means related to the combustion apparatus, in any of the first to third solving means, the reducing agent supply unit supplies ammonia containing air as a reducing agent to the combustor. Adopt means.

  In the present invention, as a fifth solving means relating to the combustion apparatus, in any one of the first to fourth solving means, the combustor mixes fuel and combustion air and supplies them to the combustion region. The means of providing a part is adopted.

  In the present invention, as means for solving the gas turbine, a combustion apparatus according to any one of the first to fifth means, a compressor for supplying compressed air as combustion air to the combustion apparatus, and a supply from the combustion apparatus And a turbine that is rotationally driven by the combustion exhaust gas.

  In the present invention, means for driving the generator with the gas turbine according to the solution means is adopted as the solution means for the power generator.

According to the present invention, since the combustor includes the reduction region, it is possible to reduce nitrogen oxide (NOx) in the combustion exhaust gas discharged from the combustor as compared with the related art.
Further, according to the present invention, since the reducing agent is supplied to the combustor, the mixing distance between the reducing agent and the combustion exhaust gas is reduced when a catalytic reduction unit using a reduction catalyst is provided at the subsequent stage of the combustor as in the conventional case. Since it can be made longer than before, nitrogen oxides (NOx) discharged from the catalyst reduction unit can be reduced more than before.

It is a block diagram which shows the structure of the electric power generating apparatus which concerns on one Embodiment of this invention. It is a characteristic view which shows the nitrogen oxide (NOx) density | concentration of the combustion apparatus which concerns on one Embodiment of this invention, and a gas turbine. It is a characteristic view which shows the reducing agent density | concentration discharged | emitted from the combustion apparatus and gas turbine which concern on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the power generator according to this embodiment includes a gas turbine 1, a generator 2, and a waste heat recovery boiler 3.

  That is, this power generator is configured to drive the generator 2 using the gas turbine 1 as a power source. The gas turbine 1 is an internal combustion engine that generates rotational power by high-pressure exhaust gas obtained by burning fuel as is well known. The generator 2 is driven to rotate by the gas turbine 1 to generate AC power having a predetermined specification (for example, three-phase AC power). Moreover, the waste heat recovery boiler 3 is provided in the middle path of the exhaust gas (combustion exhaust gas) of the gas turbine 1, and generates water vapor using the exhaust heat (waste heat) of the exhaust gas.

  The gas turbine 1 will be described in more detail. As shown in FIG. 1, the gas turbine 1 includes a compressor (compressor) 1a, a premixing unit 1b, a combustion chamber 1c, a turbine 1d, a natural gas supply unit 1e (fuel supply unit). ), An ammonia supply unit 1f (reducing agent supply unit), a mixer 1g, and a reduction catalyst chamber 1h.

  Of these components, the premixing portion 1b and the combustion chamber 1c constitute the combustor C in the present embodiment. Of these components, the combustor C, the natural gas supply unit 1e, the ammonia supply unit 1f, the mixer 1g, and the reduction catalyst chamber 1h constitute a combustion apparatus (reference number omitted) in the present embodiment. Further, among the above components, the ammonia supply unit 1f and the reduction catalyst chamber 1h constitute a catalyst reduction unit in the present embodiment.

  The compressor 1a is an axial flow type rotary compressor in which a rotating shaft is axially coupled to an output shaft of the turbine 1d. The compressor 1a compresses air taken in from the atmosphere by rotating using the turbine 1d as a power source. The obtained air (compressed air) is supplied to the premixing part 1b. That is, the compressor 1a generates primary combustion air (compressed air) to be used for combustion of fuel in the combustor C and supplies it to the premixing unit 1b. Note that the compression ratio of air in the compressor 1 a is appropriately set according to the specifications of the combustor C.

  The combustor C includes a premixing portion 1b in the front stage of the combustion chamber 1c. The premixing unit 1b is a functional unit that mixes the primary combustion air supplied from the compressor 1a with the fuel supplied from the natural gas supply unit 1e and the ammonia supply unit 1f, and a mixed gas obtained by the mixing. Is supplied to the combustion chamber 1c. The fuel in the combustor C is the natural gas supplied from the natural gas supply unit 1e and the ammonia for fuel supplied from the ammonia supply unit 1f. The premixing unit 1b is used for the fuel composed of natural gas and fuel ammonia. The primary combustion air is mixed at a stoichiometric ratio or at a ratio in the vicinity of the stoichiometric ratio to generate a mixed gas.

  The combustion chamber 1c has an internal space (combustion space) having a combustion region R1 and a reduction region R2. The combustion region R1 is a space located upstream in the flow direction of the mixed gas supplied from the premixing unit 1b, and burns the mixed gas supplied from the premixing unit 1b. That is, in the combustion region R1, the fuel is burned by the primary combustion air, so that high-temperature and high-pressure combustion exhaust gas is generated while containing nitrogen oxides (NOx).

  The reduction region R2 is a space adjacent to the downstream side of the combustion region R1, and reduces the nitrogen oxide (NOx) by primary reduction ammonia supplied from the ammonia supply unit 1f via the mixer 1g. That is, in this reduction region R2, nitrogen oxides (NOx) contained in the combustion exhaust gas are decomposed into nitrogen gas and water (water vapor). In addition to the primary reduction ammonia, secondary combustion air is supplied from the mixer 1g to the reduction region R2. Therefore, in the reduction region R2, in addition to the reduction reaction of nitrogen oxide (NOx), the unburned portion of the fuel contained in the combustion exhaust gas burns.

  Here, ammonia is generally known as a substance that combusts but has low combustibility (difficult to combust). However, in the combustion region R1, the fuel is in a stoichiometric ratio or in the vicinity of the stoichiometric ratio, and ammonia for fuel. Is burned in a state where it is mixed with natural gas, it is possible to stably burn (oxidize) the fuel ammonia as fuel. Ammonia is well known as a reducing substance for nitrogen oxides (NOx). In the reduction region R2, nitrogen oxide (NOx) is decomposed by using primary reducing ammonia as a reducing agent.

  The turbine 1d is an axial flow turbine that uses combustion exhaust gas (high-temperature high-pressure exhaust gas) supplied from the combustion chamber 1b as a driving fluid. The output shaft of the turbine 1d is axially coupled to the rotating shaft of the compressor 1a and the rotating shaft of the generator 2. The turbine 1 d is a power source that generates rotational power by combustion exhaust gas, and drives the generator 2.

  Here, although the pressure and temperature of the combustion exhaust gas are recovered by power recovery by the turbine 1d, it still has exhaust heat of about 500 ° C. and is supplied to the waste heat recovery boiler 3. The waste heat recovery boiler 3 generates steam by using the exhaust heat of such combustion exhaust gas as a heat source, and supplies the combustion exhaust gas contributing to the generation of the steam to the reduction catalyst chamber 1h.

  The reduction catalyst chamber 1h is a chamber filled with a reduction catalyst that assists in the reduction of nitrogen oxides (NOx). The reduction catalyst chamber 1h receives the combustion exhaust gas supplied from the combustor C, and converts the nitrogen oxides in the combustion exhaust gas. Remove using reducing catalyst. This reduction catalyst is a well-known thing containing platinum and palladium.

  As shown in the drawing, secondary reduction ammonia is supplied as a reducing agent from the ammonia supply section 1f to the passage path of the combustion exhaust gas connecting the waste heat recovery boiler 3 and the reduction catalyst chamber 1h. In the reduction catalyst chamber 1h, nitrogen oxide (NOx) in the combustion exhaust gas is reduced by the action of the secondary reduction ammonia and the reduction catalyst. That is, nitrogen oxides (residual nitrogen oxides) that have not been reduced in the reduction region R2 in the combustion chamber 1c are finally reduced in the reduction catalyst chamber 1h.

  The natural gas supply unit 1e is a fuel supply unit that supplies a predetermined amount of natural gas as fuel to the premixing unit 1b. The ammonia supply unit 1f supplies a predetermined amount of fuel ammonia to the premixing unit 1b as fuel, and supplies primary reduction ammonia as a reducing agent to the reduction region R2 in the combustion chamber 1c, and the waste heat recovery boiler 3 Secondary reduction ammonia is supplied to the passage of the combustion exhaust gas between the catalyst and the reduction catalyst chamber 1h. The flow rate of natural gas in the natural gas supply unit 1e and the flow rates of fuel ammonia, primary reduction ammonia, and secondary reduction ammonia in the ammonia supply unit 1f are appropriately controlled by a control device (not shown).

  The mixer 1g mixes the primary reducing ammonia supplied from the ammonia supply unit 1f and the secondary combustion air supplied from the compressor 1a to form a second mixed gas, and the second mixed gas is used as a combustion chamber. It is a gas mixer supplied to 1c. The mixer 1g is provided with a stirring mechanism (a baffle plate or a stirring blade) in the passage path of the second mixed gas in order to improve the mixing state of the primary reducing ammonia and the secondary combustion air. ing.

  Next, the operation of the power generation apparatus configured as described above, particularly the operation of the combustion apparatus and the gas turbine 1, will be described in detail with reference to FIG. 2 and FIG.

  In the gas turbine 1 according to the present embodiment, the compressed air (primary combustion air) generated by the compressor 1a is in a stoichiometric ratio or amount with fuel (natural gas and fuel ammonia) in the premixing section 1b of the combustor C. A mixed gas is generated by mixing in the vicinity of the stoichiometric ratio. And this mixed gas is supplied to the combustion area | region R1 of the combustion chamber 1c from the premixing part 1b, and combusts by being ignited by the burner in the said combustion area | region R1.

  Since the above mixed gas is a mixture of primary combustion air and fuel (natural gas and fuel ammonia) in a stoichiometric ratio or a proportion close to the stoichiometric ratio, almost no unburned matter is generated in the combustion region R1. The fuel burns but some unburned fuel may remain. The combustion exhaust gas generated in the combustion region R1 is a high-temperature and high-pressure exhaust gas containing nitrogen oxides (NOx) and some unburned fuel. The temperature of the combustion exhaust gas is, for example, 800 to 1500 ° C., and the pressure of the combustion exhaust gas is, for example, about 20 atmospheres (about 2 MPa).

  Such combustion exhaust gas is subjected to a reduction process and a two-stage combustion process in a reduction region R2 to which primary reduction ammonia and secondary combustion air are supplied. In other words, nitrogen oxides (NOx) in combustion exhaust gas are reduced by primary reduction ammonia in a high-temperature and high-pressure atmosphere and thermally decomposed into nitrogen gas and water vapor (water). Combustion treatment (oxidation treatment) is performed by the working air. Therefore, the combustion exhaust gas exhausted from the combustor C is a high-temperature and high-pressure exhaust gas from which most of nitrogen oxides (NOx) and unburned fuel have been removed.

  FIG. 2 is a characteristic diagram showing the nitrogen oxide concentration (NOx concentration) of the combustion exhaust gas at the outlet of the combustor C. In this characteristic diagram, the horizontal axis represents the ratio of the calorific value (ammonia calorific value) of the ammonia for fuel and the ammonia for primary reduction to the total input fuel calorie of natural gas, fuel ammonia and primary reducing ammonia in the combustor C, and the vertical axis. Is the nitrogen oxide concentration (NOx concentration). According to this characteristic diagram, it is possible to significantly reduce the nitrogen oxide concentration (NOx concentration) of the combustion exhaust gas by increasing the flow rate of the primary reducing ammonia supplied to the reduction region R2.

  That is, according to this embodiment, it is possible to improve the reduction performance of NOx (nitrogen oxide) in the combustion exhaust gas by supplying ammonia for primary reduction to the combustor C in a high temperature and high pressure environment, Therefore, it is possible to greatly reduce nitrogen oxide (NOx) in the combustion exhaust gas exhausted from the combustor C.

  Such combustion exhaust gas (high-temperature high-pressure exhaust gas) is supplied to the turbine 1d, whereby thermal energy is converted into kinetic energy, and the generator 2 is driven. That is, the thermal energy of the combustion exhaust gas (high-temperature high-pressure exhaust gas) is recovered as kinetic energy in the turbine 1d. The combustion exhaust gas (high-temperature high-pressure exhaust gas) whose energy has been recovered by the turbine 1d is still a high-temperature high-pressure exhaust gas having a temperature close to 500 ° C., which is supplied from the turbine 1d to the waste heat recovery boiler 3 to recover the waste heat and generate steam. generate.

  Further, the combustion exhaust gas (high-temperature high-pressure exhaust gas) whose energy has been recovered by the waste heat recovery boiler 3 is still a high-temperature exhaust gas having a temperature close to 300 °, and is supplied from the waste heat recovery boiler 3 to the reduction catalyst chamber 1h for reduction treatment. The

  On the other hand, since the ammonia for secondary reduction is supplied from the ammonia supply unit 1f to the flow path of the combustion exhaust gas connecting the reduction catalyst chamber 1h and the waste heat recovery boiler 3, the combustion exhaust gas is separated from the ammonia for secondary reduction. The mixed catalyst is supplied to the reduction catalyst chamber 1h. Then, the residual nitrogen oxide (residual NOx) in the combustion exhaust gas is reduced by secondary reduction ammonia and a reduction catalyst.

  Here, the combustion exhaust gas exhausted from the combustor C may contain primary reducing ammonia (residual ammonia) that has not contributed to the reduction treatment of nitrogen oxides (NOx) in the reduction region R2. That is, when the secondary combustion air is supplied to the reduction region R2 of the combustor C, the unburned portion of the fuel ammonia is combusted and the residual amount of the fuel ammonia is sufficiently reduced, but the reduction region R2 Depending on the flow rate of the primary reducing ammonia supplied to the combustion exhaust gas, the combustion exhaust gas exhausted from the combustor C may contain residual ammonia.

  FIG. 3 is a characteristic diagram showing the ammonia concentration in the combustion exhaust gas at the outlet of the combustor C. In this characteristic diagram, the horizontal axis represents the ratio of the amount of ammonia heat to the total input fuel heat amount, as in FIG. 2, and the vertical axis represents the ammonia concentration. According to this characteristic diagram, the ammonia concentration in the combustion exhaust gas increases by increasing the flow rate of the primary reducing ammonia supplied to the reduction region R2, and the ammonia concentration also increases by increasing the ratio of the combustion ammonia in the combustion region R1. Can be seen to rise.

  That is, residual nitrogen oxide (residual NOx) in the combustion exhaust gas is supplied to the reduction catalyst chamber 1h via the waste heat recovery boiler 3 in a state already mixed with residual ammonia in the reduction region R2 of the combustor C. . Therefore, the flow rate of the ammonia for secondary reduction to be supplied to the combustion exhaust gas flow path connecting the reduction catalyst chamber 1h and the waste heat recovery boiler 3 is reduced.

  Further, the mixing distance of the residual nitrogen oxide (residual NOx) with the residual ammonia is from the combustor C to the reduction catalyst chamber 1h, and is longer than the secondary reduction ammonia supplied to the flow path. Further, since the combustion exhaust gas supplied from the combustor C to the waste heat recovery boiler 3 passes through the turbine 1d, residual nitrogen oxide (residual NOx) and residual ammonia (primary reduction ammonia) are sufficiently mixed.

Therefore, according to the present embodiment, since the combustor C includes a reduction region, that is, primary reduction ammonia is supplied to the combustor C, nitrogen oxides in the combustion exhaust gas discharged from the combustor C to the turbine 1d. (NOx) can be reduced as compared with the prior art.
Further, according to the present embodiment, since the primary reduction ammonia is supplied to the combustor C, the mixing distance between the combustion exhaust gas and the primary reduction ammonia can be made longer than before, and thus the reduction catalyst chamber 1h. Thus, nitrogen oxides (NOx) in the combustion exhaust gas released from the atmosphere to the atmosphere can be reduced as compared with the prior art.
Further, since the turbine 1d and the waste heat recovery boiler 3 function as a mixer for the combustion exhaust gas and primary reduction ammonia supplied from the combustor C to the reduction catalyst chamber 1h, the combustion exhaust gas and primary reduction ammonia are good. To be mixed. Thereby, the amount of unreacted ammonia exhausted from the reduction catalyst chamber 1h to the atmosphere can be sufficiently reduced.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, the fuel is a mixed gas of natural gas and fuel ammonia, but the present invention is not limited to this. Other single fuel (natural gas) or composite fuel may be used as the fuel.

(2) In the above embodiment, the combustion region R1 and the reduction region R2 are formed in the combustion chamber 1c, but the present invention is not limited to this. For example, a second combustion region may be formed between the combustion region (first combustion region) and the reduction region, natural gas may be combusted in the first combustion region, and fuel ammonia may be combusted in the second combustion region. . In this case, since the flame-retardant ammonia for fuel is burned under the high-temperature environment generated in the first combustion region, it is possible to improve the combustibility of the fuel-use ammonia and reduce the unburned content.

(3) Although the primary reducing ammonia and the secondary reducing ammonia are used as the reducing agent in the above embodiment, the present invention is not limited to this. Instead of ammonia, other reducing agents such as urea may be used.

(4) In the above embodiment, the waste heat recovery boiler 3 is provided and the waste heat recovery is performed, but the present invention is not limited to this. If necessary, the waste heat recovery boiler 3 may be deleted, and the turbine 1d and the reduction catalyst chamber 1h may be directly connected.

(5) Although the premixing portion 1b is provided in the combustor C in the above embodiment, the present invention is not limited to this. You may employ | adopt the structure which supplies the air for secondary combustion and ammonia for primary reduction to a combustor separately. In the above embodiment, the mixer 1g is provided with a stirring mechanism. However, this stirring mechanism has a demerit of generating a pressure loss, and may be omitted.

C Combustor 1 Gas turbine 1a Compressor 1b Premixing unit 1c Combustion chamber 1d Turbine 1e Natural gas supply unit (fuel supply unit)
1f Ammonia supply part (reducing agent supply part)
1g Mixer 1h Reduction catalyst chamber (catalyst reduction part)
2 Generator R1 Combustion zone R2 Reduction zone 3 Waste heat recovery boiler

Claims (7)

A predetermined fuel supply unit;
A combustor for combusting the fuel supplied from the fuel supply unit using combustion air;
A reducing agent supply unit for supplying a predetermined reducing agent to the combustor;
A catalytic reduction unit that receives the combustion exhaust gas supplied from the combustor and removes nitrogen oxides in the combustion exhaust gas using a reduction catalyst;
The combustor includes a combustion region in which the fuel is combusted, and a reduction region in which nitrogen oxides generated in the combustion region are reduced with the reducing agent.   The combustion apparatus according to claim 1, wherein the fuel supply unit supplies natural gas and ammonia as fuel to the combustor.   The combustion apparatus according to claim 2, wherein the fuel supply unit supplies the natural gas and the ammonia to the combustor in a stoichiometric ratio with respect to combustion air.   The combustion apparatus according to any one of claims 1 to 3, wherein the reducing agent supply unit supplies ammonia including air to the combustor as the reducing agent.   The combustion apparatus according to any one of claims 1 to 4, wherein the combustor includes a premixing unit that mixes the fuel and combustion air and supplies the fuel and the combustion air to the combustion region. A combustion apparatus according to any one of claims 1 to 5;
A compressor for supplying compressed air as the combustion air to the combustion device;
A gas turbine comprising: a turbine that is rotationally driven by combustion exhaust gas supplied from the combustion device. A generator is driven by the gas turbine according to claim 6.

Images