Exhaust gas treatment equipment and power generation equipment

Abstract

To appropriately remove NOX in exhaust gas while preventing leakage of unreacted NH3.SOLUTION: Oxidation means 9 for oxidizing an insoluble NOX in a gas phase into a water-soluble NOX is provided between a denitration device 4 and a desulfurization device 11, thereby: enabling denitration of NOX even on a downstream side of an air preheater 6; reducing an amount of ammonia (NH3) used for NOX removal treatment in the denitration device 4; preventing leakage of unreacted NH3 to the downstream side; and appropriately removing NOX in the exhaust gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas treatment facility that treats exhaust gas from a combustion means, and a power generation facility that has the exhaust gas treatment facility. [Background technology]

[0002] Boiler facilities using carbonaceous fuels, including coal, are equipped with boilers that generate steam by burning fuel to generate power. This type of boiler facility has a problem with nitrogen oxides (NO) in the exhaust gas emitted from the boiler. X The system is equipped with a denitration unit that removes NOx by reacting the exhaust gas with ammonia (NH3) in the presence of a denitration catalyst, and an air preheater (AH) that uses the heat of the exhaust gas that has passed through the denitration unit to preheat the combustion air in the boiler. Furthermore, a dust collector and desulfurization unit are also installed to treat impurities in the exhaust gas whose heat has been recovered by the air preheater.

[0003] In the denitrification equipment, (NH3 / NO X ) molar ratio, the denitrification rate can be increased, so NO X In order to properly remove sulfur oxides (SO ), a sufficient amount of NH3 is supplied to the denitration device. When the denitration catalyst deteriorates, it becomes necessary to supply an excess amount of NH3. If an excess amount of NH3 is supplied, there is a risk that unreacted NH3 will leak downstream of the denitration device. If NH3 leaks, it will increase the amount of sulfur oxides (SO ) in the exhaust gas. X ) and when the exhaust gas temperature drops in the air preheater, ammonium sulfate compounds such as acid ammonium sulfate are generated, which may condense in the air preheater flow path.

[0004] When condensate adheres to the air preheater and forms deposits, it causes an increase in the pressure loss (differential pressure) of the exhaust gas. For this reason, a technology has been proposed that measures the differential pressure of the air preheater downstream of the denitration unit and corrects the concentration of leaked NH3 (Patent Document 1). By measuring the differential pressure of the air preheater downstream of the denitration unit and correcting the concentration of leaked NH3, it is possible to minimize the leakage of NH3.

[0005] However, even if NH3 leakage is minimized, NO X A minimum amount of NH3 is required to clear the emission standards, and it has not been possible to eliminate NH3 leakage. In addition, a fundamental solution to the adhesion of condensate to the air preheater requires shutting down the plant to clean the air preheater, and adding or replacing the denitration catalyst in the denitration unit, which has resulted in high costs. For this reason, it has been necessary to develop a system that does not leak NH3 downstream of the denitration unit and that also reduces NO in the exhaust gas. X The reality is that there is a demand for technology that can adequately remove these substances. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 2710985 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above circumstances, and is a method for reducing nitrogen oxides (NO) in exhaust gases without the need to supply a large amount of ammonia (NH3) to increase the processing capacity of a denitration device, without leaking unreacted NH3. X The present invention aims to provide an exhaust gas treatment facility that can appropriately remove .

[0008] The present invention has been made in view of the above circumstances, and is a method for reducing nitrogen oxides (NO) in exhaust gases without the need to supply a large amount of NH3 in order to increase the processing capacity of a denitration device, without leaking unreacted NH3. X The present invention aims to provide a power generation facility having an exhaust gas treatment facility capable of appropriately removing . [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides an exhaust gas treatment facility according to claim 1, which is provided downstream of a combustion means that discharges exhaust gas by combustion of a carbon-based fuel, and which is supplied with ammonia (NH3) from an NH3 supply means to treat nitrogen oxides (NO X a treatment means provided downstream of the treatment means for treating the exhaust gas; and an oxidizing agent supply means provided downstream of the treatment means for supplying an oxidizing agent to the treatment means, thereby removing insoluble NOx mainly containing NOx insoluble in water from the exhaust gas. X In the gas phase, water-soluble NO X and an oxidation means provided downstream of the oxidation means for oxidizing the water-soluble NO oxidized by the oxidation means. X is dissolved and oxidized in the liquid phase, and the sulfur oxides (SO X and a desulfurization device for desulfurizing the slag.

[0010] In the present invention according to claim 1, insoluble NO X In the gas phase, water-soluble NO X By providing an oxidation means for oxidizing NOx, NOx can be generated downstream of the treatment means. X In order to improve the processing capacity of the denitration equipment, X There is no need to supply a large amount of NH3 to increase the molar ratio of NO X This reduces the amount of NH3 in the exhaust gas, preventing unreacted NH3 from leaking downstream. X can be appropriately removed.

[0011] This significantly reduces the impact of NH3 on the treatment means. For example, the deposition of deposits due to condensation of ammonium sulfate, acid ammonium sulfate, etc. on the flow path of the air preheater can be significantly reduced.

[0012] Therefore, there is no need to supply a large amount of NH3 to increase the processing capacity of the denitration equipment, and there is no leakage of unreacted NH3, and the NO in the exhaust gas is X can be appropriately removed.

[0013] The exhaust gas treatment equipment of the present invention according to claim 2 is characterized in that in the exhaust gas treatment equipment described in claim 1, the treatment means is an air preheating means that uses the heat of the exhaust gas to preheat the air for combustion in the combustion means.

[0014] In the present invention according to claim 2, NO X This reduces the amount of NH3 in the treatment means and prevents unreacted NH3 from leaking downstream, significantly reducing the impact of NH3 on the treatment means. It also significantly reduces the adhesion of deposits due to condensation of ammonium sulfate, acid ammonium sulfate, etc. to the flow path of the air preheating means (air preheater), thereby suppressing an increase in pressure loss (differential pressure).

[0015] As the treatment means, a dust collector that separates and removes extremely fine suspended matter such as dust and mist in the exhaust gas, and a heat exchanger that recovers heat from the exhaust gas can be applied.

[0016] The exhaust gas treatment equipment of the present invention according to claim 3 is the exhaust gas treatment equipment according to claim 2, characterized in that the oxidant supply means is an ozone supply means that supplies ozone.

[0017] In the present invention according to claim 3, ozone is supplied as an oxidizing agent to reduce insoluble NO in exhaust gas, which mainly contains NO that is insoluble in water. X In the gas phase, water-soluble NO X Water-soluble NO oxidized in the gas phase can be oxidized to N2O5 (e.g., N2O5). X (e.g., N2O5) is converted into NO in the liquid phase by a downstream desulfurization device. X is oxidized to (NO3 - and then treated, for example, in wastewater.

[0018] The exhaust gas treatment system of the present invention according to claim 4 is the exhaust gas treatment system according to claim 3, wherein NO 2 is present upstream of the oxidation means. X The present invention is characterized by comprising a control means for controlling the amount of ozone supplied from the ozone supply means based on the amount of ozone.

[0019] In the present invention according to claim 4, the amount of NH3 is suppressed to suppress the leakage of NH3, and NO that was not completely denitrified by the denitration device is removed. X Based on the amount of ozone delivered, water-soluble NO X Therefore, NO X can be processed.

[0020] Furthermore, in the exhaust gas treatment equipment of the present invention according to claim 5, in the exhaust gas treatment equipment according to claim 4, the control means controls the NOx removal device upstream of the NOx removal device. X The supply of NH3 from the NH3 supply means is controlled based on the amount of NH3, thereby suppressing leakage of unreacted NH3 downstream of the denitration device.

[0021] In the present invention according to claim 5, NO exhausted from the combustion means X For example, NH3 / NO X The amount of NH3 supplied is controlled so that the molar ratio becomes a predetermined value (for example, molar ratio <1).

[0022] In order to achieve the above object, the power generation equipment of the present invention according to claim 6 is characterized by comprising an exhaust gas treatment equipment according to any one of claims 1 to 5, and an electric power generation means for expanding a high-temperature, high-pressure fluid obtained by the combustion means of the exhaust gas treatment equipment to obtain electric power generation power.

[0023] In the present invention according to claim 6, it is not necessary to supply a large amount of NH3 to increase the processing capacity of the denitration device, and a state in which there is no leakage of NH3 is maintained, and further, the NO in the exhaust gas is reduced. X The power generation facility can be provided with an exhaust gas treatment facility that can appropriately remove the above.

[0024] Furthermore, the power generation facility of the present invention according to claim 7 is the power generation facility according to claim 6, wherein the combustion means is a boiler that obtains high-temperature, high-pressure steam by burning a carbonaceous fuel including coal and discharges exhaust gas, and the power generation means has a steam turbine into which the steam obtained in the boiler is introduced and expanded to obtain driving force, and power generation means that obtains electric power by driving the steam turbine.

[0025] In the present invention according to claim 7, in a power generation facility that generates electricity by expanding high-temperature, high-pressure steam obtained in a boiler with a steam turbine, there is no need to supply a large amount of NH3 to increase the processing capacity of the denitrification device, and there is no leakage of unreacted NH3, and the NO in the exhaust gas is reduced. X can be appropriately removed. [Effects of the Invention]

[0026] The exhaust gas treatment equipment of the present invention does not need to supply a large amount of ammonia (NH3) to increase the treatment capacity of the denitration device, and it is possible to prevent the leakage of unreacted NH3, and further to reduce nitrogen oxides (NO X ) can be appropriately removed.

[0027] The power generation equipment of the present invention does not need to supply a large amount of NH3 to increase the processing capacity of the denitration equipment, and it is possible to eliminate the leakage of unreacted NH3 and further reduce the NO in the exhaust gas. X Therefore, it is possible to provide a power generation facility having an exhaust gas treatment facility that can appropriately remove the above-mentioned substances. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a schematic system diagram of a power generation facility having an exhaust gas treatment facility according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram of a control means. DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 shows a schematic diagram of the overall system of equipment in a power generation facility having an exhaust gas treatment facility according to one embodiment of the present invention, and FIG. 2 shows a block diagram of a control means for controlling the supply of NH3 and an oxidizing agent (ozone).

[0030] As shown in FIG. 1, pulverized coal is supplied from a mill 2 to a boiler 1, which serves as combustion means for discharging exhaust gas by burning a carbonaceous fuel. A denitration device 4 is provided downstream of the boiler 1 via an exhaust passage 3, and ammonia (NH3) is supplied to the denitration device 4 from an ammonia (NH3) supply means 5 via the exhaust passage 3. By supplying NH3 to the denitration device 4, nitrogen oxides (NO X ) is removed.

[0031] An air preheater 6 serving as a treatment means (air preheating means) is provided downstream of the denitration device 4 via the exhaust passage 3. Furthermore, a dust collector 8 for removing soot and dust is provided downstream of the air preheater 6. The air preheater 6 uses the residual heat of the exhaust gas that has passed through the denitration device 4 to preheat the combustion air in the boiler 1 and the air for transporting pulverized coal sent to the mill 2.

[0032] Downstream of the dust collector 8, NO in the exhaust gas X In the gas phase, water-soluble NO X The oxidation means 9 is provided with ozone as an oxidant supplied from an oxidant supply means 10.

[0033] In the oxidation means 9, ozone is supplied to oxidize insoluble NO in the exhaust gas, which mainly contains NO that is insoluble in water. X are oxidized to water-soluble nitrogen oxides (containing at least one of NO2, N2O3, N2O4, and N2O5: for example, nitrogen oxides containing mainly N2O5: N2O5).

[0034] NO by oxidation method 9 X After oxidation, the exhaust gas is sent to the desulfurization device 11. In the desulfurization device 11, water-soluble nitrogen oxides (e.g., N2O5) are dissolved to produce NO3 -(Water-soluble nitrogen oxides are dissolved and oxidized in the liquid phase), and sulfur oxides (SO X ) is removed.

[0035] Nitrogen oxides (NO3 - ) is treated appropriately and utilized as nitrate, ammonium salt, or NH3 as needed. The amount of NH3 supplied from the NH3 supply means 5 to the denitration device 4 is controlled by the control means 12. In addition, the amount of ozone supplied from the oxidizing agent supply means 10 to the oxidation means 9 is controlled by the control means 12.

[0036] The exhaust passage 3 upstream of the denitration device 4 is provided with NO X Detects the amount of upstream NO X A quantity detection means 13 is provided, and the upstream NO X NO detected by the amount detection means 13 X Amount (NO of exhaust gas from boiler 1 X The information on the amount of NH3 to be supplied to the denitration device 4 is input to the control means 12. The control means 12 is provided with an NH3 adjustment function 21 (see FIG. 2), and the amount of NH3 to be supplied to the denitration device 4 is adjusted.

[0037] The amount of NH3 supplied from the NH3 supply means 5 to the denitration device 4 is adjusted (controlled) by the control means 12, thereby reducing the amount of NOx discharged from the boiler 1. X For example, NH3 / NO X The amount of NH3 supplied can be controlled so that the molar ratio becomes a predetermined value (for example, a molar ratio <1).

[0038] The exhaust passage 3 upstream of the oxidation means 9 contains NO X Detecting downstream NO levels X A downstream NO amount detection means 14 is provided. X NO detected by the amount detection means 14 X Amount (NO in exhaust gas after soot and dust are removed by dust collector) X The information on the amount of ozone to be supplied to the oxidation means 9 is input to the control means 12. The control means 12 is provided with an oxidizing agent adjusting function 22 (see FIG. 2), which adjusts the amount of ozone to be supplied to the oxidation means 9.

[0039] The amount of ozone supplied from the oxidizing agent supply means 10 to the oxidation means 9 is adjusted (controlled) by the control means 12, so that the amount of NH3 is suppressed to suppress the leakage of NH3 (to make it a state where there is no leakage of NH3), and the NOx that was not completely denitrified by the denitration device 4 is removed. X Based on the amount of ozone supplied, NO X can be converted into water-soluble nitrogen oxides (e.g., N2O5) and treated in the desulfurization device 11. X can be processed.

[0040] In the exhaust gas treatment equipment described above, insoluble NO X By providing an oxidation means 9 for oxidizing NO to water-soluble nitrogen oxides (e.g., N2O5) in the gas phase, NO X In order to increase the processing capacity of the denitration device 4, that is, NH3 / NO X In order to increase the molar ratio of NH3, it is not necessary to supply a large amount of NH3.

[0041] This can significantly reduce the influence of NH3 on the air preheater 6. For example, the adhesion of deposits due to condensation of ammonium sulfate, acid ammonium sulfate, etc. to the flow path of the air preheater 6 can be significantly reduced.

[0042] Therefore, there is no need to supply a large amount of NH3 to increase the processing capacity of the denitration device 4, and NO X By reducing the amount of NH3 in the exhaust gas, there is no leakage of unreacted NH3. X can be appropriately removed.

[0043] In the boiler 1 equipped with the above-mentioned exhaust gas treatment equipment, high-temperature, high-pressure steam is generated by burning coal (pulverized coal), and the high-temperature, high-pressure steam is expanded in the steam turbine 25 to generate driving force. Driving the steam turbine 25 operates the power generation means 26, and electric power is generated.

[0044] Therefore, in a power generation facility where high-temperature, high-pressure steam obtained in the boiler 1 is expanded by the steam turbine 25 to generate electricity, there is no need to supply a large amount of NH3 to increase the processing capacity of the denitration device 4, and there is no leakage of unreacted NH3, and the NO in the exhaust gas is also reduced. X can be appropriately removed.

[0045] The above-described exhaust gas treatment equipment does not need to supply a large amount of NH3 to increase the treatment capacity of the denitration device 4, and is in a state where there is no leakage of unreacted NH3, and further, the NO in the exhaust gas is X can be properly removed.

[0046] The power generation facility described above does not need to supply a large amount of NH3 to increase the processing capacity of the denitration device 4, and does not leak unreacted NH3, and further, can reduce the amount of NO in the exhaust gas. X Therefore, it is possible to provide a power generation facility having an exhaust gas treatment facility that can appropriately remove the above-mentioned substances. [Industrial Applicability]

[0047] The present invention can be used in the industrial fields of exhaust gas treatment equipment and power generation equipment. [Explanation of symbols]

[0048] 1 boiler 2 mil 3 Exhaust passage 4 Denitration equipment 5 NH3 supply means 6. Air preheater 8 Dust collector 9. Oxidation Methods 10. Oxidant supply means 11 Desulfurization equipment 12 Control Means 13 Upstream No. X Amount detection means 14 Downstream No. X Amount detection means 21 NH3 adjustment function 22 Oxidant adjustment function

Claims

1. The exhaust gas is discharged from the combustion means downstream of the combustion means. ３ Ammonia (NH ３ ) is supplied to the exhaust gas, and nitrogen oxides (NO Ｘ a denitration device for denitrifying the a treatment means provided downstream of the denitration device for treating the exhaust gas; and an oxidant supply means provided downstream of the treatment means for supplying an oxidant to the exhaust gas, thereby removing insoluble NOx mainly containing NOx insoluble in water from the exhaust gas. Ｘ in the gas phase with water-soluble NO Ｘ an oxidation means for oxidizing The oxidation means is provided downstream of the oxidation means, and the water-soluble NO oxidized by the oxidation means Ｘ is dissolved and oxidized in the liquid phase, and the sulfur oxides (SO Ｘ and a desulfurization device for desulfurizing the An exhaust gas treatment facility characterized by:

2. The exhaust gas treatment equipment according to claim 1, The processing means air preheating means for preheating the air for combustion in the combustion means by utilizing the heat of the exhaust gas; An exhaust gas treatment facility characterized by:

3. The exhaust gas treatment equipment according to claim 2, The oxidant supply means It is an ozone supplying means for supplying ozone. An exhaust gas treatment facility characterized by:

4. The exhaust gas treatment equipment according to claim 3, NO upstream of the oxidation means Ｘ A control means for controlling the amount of ozone supplied from the ozone supply means based on the amount of ozone. An exhaust gas treatment facility characterized by:

5. The exhaust gas treatment equipment according to claim 4, The control means The NOx upstream of the denitration device Ｘ Based on the amount, NH ３ NH from the supply means ３ and control the supply of unreacted NH to the downstream side of the denitration device. ３ Suppressing leaks An exhaust gas treatment facility characterized by:

6. The exhaust gas treatment equipment according to any one of claims 1 to 5; and a power generating means for expanding the high-temperature, high-pressure fluid obtained by the combustion means of the exhaust gas treatment facility to generate power. A power generation facility characterized by:

7. The power generation facility according to claim 6, The combustion means is A boiler that produces high-temperature, high-pressure steam by burning carbonaceous fuels, including coal, and emits exhaust gas. The power generating means a steam turbine into which the steam obtained in the boiler is introduced and expanded to obtain driving force; a power generation means for obtaining electric power by driving the steam turbine; A power generation facility characterized by:

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