Control device, denitrification apparatus, and boiler facility

Abstract

To provide a control device, a denitrification apparatus, and a boiler facility that can achieve a consistent quantitative ratio between nitrogen oxides and reducing agents in the exhaust gas entering a denitrification container, even under variable boiler loads.SOLUTION: A control device includes a valve control unit that determines NOx distribution response data, from the opening adjustment response data, that equalizes nitrogen oxide variations across a plurality of regions indicated by the load fluctuation NOx distribution data, and controls at least one valve's opening according to the opening adjustment pattern associated with the determined NOx distribution response data.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a control device for denitrifying exhaust gas flowing through a flue of a boiler facility, a denitrification device including the control device, and a boiler facility including the denitrification device. [Background technology]

[0002] The denitration device includes a plurality of reducing agent nozzles provided in the flue of the boiler facility, and a denitration reactor located downstream of the plurality of reducing agent nozzles in the flue. The plurality of reducing agents are sprayed into the flue gas flowing through the flue toward the denitration reactor. The exhaust gas is denitrified by a reduction reaction between the nitrogen oxides in the flue gas and the reducing agent in the denitration vessel.

[0003] In order to improve the denitration performance of a denitration device, it is necessary to make the ratio of the amount of nitrogen oxides to the amount of reducing agent uniform among the multiple sections that make up the inlet cross section of the denitration reactor. However, because the flow of exhaust gas from the multiple reducing agent nozzles to the denitration reactor is complex, even if the reducing agent is uniformly sprayed from each of the multiple reducing agent nozzles, the nitrogen oxides and the reducing agent are not necessarily mixed uniformly at the inlet of the denitration reactor.

[0004] There are several known methods for adjusting the supply amount of reducing agent aimed at solving the above problems. For example, the denitration device disclosed in Patent Document 1 uses a reducing agent flow model when determining the injection amount of reducing agent from each of a plurality of reducing agent nozzles. The reducing agent flow model is a model that shows the correlation between the injection amount of reducing agent from each of a plurality of reducing agent nozzles and the concentration distribution of the reducing agent on the inlet side of the denitration reactor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6470675 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the flow of the exhaust gas flowing inside the flue, which generally has a bent structure, is very complicated. Therefore, it is difficult to construct a reducing agent flow model that accurately shows the correlation between the injection amount of the reducing agent and the concentration distribution of the reducing agent at the inlet side of the denitration reactor. In particular, when the boiler load fluctuates, the flow state of the exhaust gas changes significantly, so that even if the above-mentioned reducing agent flow model is used, there is a risk that the denitration performance of the denitration device will not be improved.

[0007] An object of the present disclosure is to provide a control device, a denitration device, and a boiler facility that can uniformly maintain the ratio of nitrogen oxide amounts to reducing agent amounts in exhaust gas flowing into a denitration container even when the boiler load fluctuates. [Means for solving the problem]

[0008] A control device according to at least one embodiment of the present disclosure includes: A control device configured to control an opening degree of each of a plurality of valves for adjusting a supply amount of a reducing agent to an exhaust gas discharged from a boiler, a first acquisition unit for acquiring load fluctuation NOx distribution data in which a degree of change in the amount of nitrogen oxides caused by a change in boiler load is assigned to each of a plurality of regions constituting a cross section of the flue through which the exhaust gas flows; a second acquisition unit for acquiring opening degree adjustment response data in which a plurality of opening degree adjustment patterns, which are patterns for adjusting the opening degree of at least one of the plurality of valves, are associated in advance with a plurality of NOx distribution response data indicating a tendency of change in the amount of nitrogen oxides generated in each of the plurality of regions in response to the opening degree adjustment of the at least one valve; a valve control unit that identifies, from the opening degree adjustment response data, the NOx distribution response data for leveling out the degree of change in the amount of nitrogen oxide occurring in each of the plurality of regions indicated by the load fluctuation NOx distribution data, and controls the opening degree of the at least one valve in accordance with the opening degree adjustment pattern associated with the identified NOx distribution response data; Equipped with.

[0009] A denitration device according to an embodiment of the present disclosure includes: The control device; a plurality of reducing agent nozzles configured to inject the reducing agent into the exhaust gas flowing through the flue; a plurality of reducing agent supply passages for supplying the reducing agent to each of the plurality of reducing agent nozzles; the plurality of valves disposed in the plurality of reducing agent supply paths, respectively; a denitration reactor including a denitration catalyst disposed downstream of the plurality of reducing agent nozzles in the flue; Equipped with.

[0010] A boiler facility according to an embodiment of the present disclosure includes: Boiler and a flue through which exhaust gas generated in the boiler flows; The denitration device for denitrifying the exhaust gas flowing through the flue gas stream; Equipped with. Effect of the Invention

[0011] According to the present disclosure, it is possible to provide a control device, a denitration device, and a boiler facility that can uniformly maintain the ratio of the amount of nitrogen oxides to the amount of reducing agent in the exhaust gas flowing into the denitration container even when the boiler load fluctuates. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of a boiler facility according to an embodiment. [Diagram 2] FIG. 1 is a schematic diagram of a NOx measuring instrument according to one embodiment. [Diagram 3]FIG. 4 is a schematic diagram of opening adjustment response data according to an embodiment. [Figure 4] FIG. 2 is a schematic diagram of load change NOx distribution data according to one embodiment. [Diagram 5] FIG. 2 is a schematic diagram of pre-load change data according to an embodiment. [Figure 6] FIG. 13 is a schematic diagram of post-load change data according to an embodiment. [Figure 7] FIG. 2 is a schematic diagram of a control device according to an embodiment. [Figure 8] 4 is a flowchart of a denitration control process according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such a configuration, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained. On the other hand, the expressions "comprise", "include", or "have" a certain element are not exclusive expressions excluding the presence of other elements. In addition, the same components are denoted by the same reference numerals and the description thereof may be omitted.

[0014] <Outline of boiler facility 1> 1 is a schematic diagram showing a boiler facility 1 according to an embodiment of the present disclosure. The boiler facility 1, which is incorporated in a power plant, includes a boiler 3. The boiler 3 is supplied with a fuel, such as coal, oil, natural gas, ammonia fuel, or hydrogen fuel, and air as an oxidant. Steam generated by utilizing heat produced by combustion of the fuel is supplied to a steam turbine (not shown) connected to a generator (not shown).

[0015] The boiler facility 1 further includes a flue 4 that forms a flow path for exhaust gas generated by the combustion of fuel, and a denitrification device 5 for denitrifying the exhaust gas flowing through the flue 4. The denitrified exhaust gas passes through an air heater 9 and the like disposed in the flue 4 and is discharged into the atmosphere. The air heater 9 is configured to heat air (outside air) to be supplied to the boiler 3, using the exhaust gas flowing through the flue 4 as a heat source. The outlet of the flue 4 is located downstream of the air heater 9 (detailed illustration is omitted in FIG. 1).

[0016] The denitration device 5 includes a plurality of reducing agent nozzles 51 configured to inject a reducing agent into the exhaust gas flowing through the flue 4, and a denitration reactor 57 including a denitration catalyst disposed downstream of the plurality of reducing agent nozzles 51 in the flue 4. The reducing agent injected from the reducing agent nozzle 51 mixes with nitrogen oxides in the exhaust gas. The exhaust gas including the reducing agent and nitrogen oxides flows into the denitration reactor 57, where a reduction reaction of the nitrogen oxides occurs. The reducing agent is a compound including ammonia or urea. The denitration catalyst is a catalyst for promoting the reduction reaction of the nitrogen oxides, and includes, for example, vanadium or tungsten.

[0017] The denitration device 5 further includes a storage section 59 that stores a reducing agent, a plurality of reducing agent supply passages 52 for supplying the reducing agent from the storage section 59 to each of the plurality of reducing agent nozzles 51, and a plurality of valves 55 arranged in each of the plurality of reducing agent supply passages 52. The plurality of reducing agent nozzles 51 are arranged to inject the reducing agent at different positions in the flue 4. Each of the valves 55 is a flow rate adjustment valve. By adjusting the opening degree of each of the valves 55, the amount of reducing agent supplied to each of the reducing agent nozzles 51 can be adjusted.

[0018] If the distribution of nitrogen oxides is uniform in the flow passage cross section of the outlet 57b of the denitration reactor 57, it is understood that the denitration device 5 exhibits high denitration performance. For this reason, in order to make the distribution of the amount of nitrogen oxides uniform in the flow passage cross section of the outlet 57b, it is necessary to make the ratio of the amount of nitrogen oxides to the amount of reducing agent uniform at the inlet 57a of the denitration reactor 57. More specifically, it is required that the ratio of the amount of nitrogen oxides to the amount of reducing agent is uniform among the multiple sections constituting the flow passage cross section of the inlet 57a. Since it is difficult to make the amount of nitrogen oxides uniform in the flow passage cross section of the inlet 57a, it is required that there is an amount of reducing agent corresponding to the amount of nitrogen oxides in each of the multiple sections constituting the flow passage cross section. In this example, the amount of nitrogen oxides is represented by the NOx concentration, and the amount of reducing agent is represented by the reducing agent concentration. Hereinafter, the ratio of the NOx concentration to the reducing agent concentration may be referred to as the "mixed concentration ratio".

[0019] According to the findings of the inventors of the present application, even if the mixture concentration ratio is maintained uniform at the inlet 57a, when the boiler load fluctuates, the flow state of the exhaust gas changes significantly and the mixture concentration ratio becomes non-uniform. Therefore, after the boiler load fluctuates, it is necessary to control the injection amount of the reducing agent from the reducing agent nozzle 51 so that the mixture concentration ratio at the inlet 57a becomes uniform.

[0020] Therefore, in this embodiment, when fluctuations in the boiler load occur during the rated operation of the boiler 3, the opening degrees of the respective valves 55, which are components of the denitration device 5, are controlled by the control device 10. In other words, when fluctuations in the boiler load occur, the supply amount of the reducing agent to the exhaust gas is adjusted through the control of the opening degrees of the plurality of valves 55 by the control device 10.

[0021] Here, the boiler load may be represented by the power generation amount, may be represented by the exhaust gas flow rate at a specific position in the flue 4, or may be represented by the amount of steam generated in the boiler 3. Also, before fluctuations in the boiler load occur, the boiler 3 has been performing rated operation for, for example, 6 hours or more or 12 hours or more. The time of the partial load operation of the boiler 3 executed along with the fluctuations in the boiler load may be, for example, 6 hours or more or 12 hours or more.

[0022] <NOx meter 60> As shown in FIG. 1, the denitration device 5 further includes a NOx meter 60. The NOx meter 60 is configured to measure the distribution of the NOx concentration at the cross section 6, which is the flow path cross section of the flue 4 located between the denitration reactor 57 and the air heater 9.

[0023] FIG. 2 is a schematic diagram of the NOx meter 60 according to an embodiment of the present disclosure. The cross section 6 includes a plurality of regions 7, and the NOx meter 60 is configured to measure the NOx concentration in each of the plurality of regions 7. In the example of this figure, the cross section 6 is virtually divided into three in the front - rear direction and also virtually divided into three in the left - right direction. That is, the number of the plurality of regions 7 is nine. However, FIG. 2 is merely an exemplary schematic diagram, and the cross section 6 may be divided into 10 or more in the left - right direction, for example.

[0024] The NOx measuring instrument 60 is configured to measure the NOx concentration by sucking in the exhaust gas flowing through each of the regions 7. Specifically, the NOx measuring instrument 60 includes a plurality of guide pipes 61 provided corresponding to the plurality of regions 7, a plurality of on-off valves 62 arranged in each of the guide pipes 61, an analyzer 65 for measuring the concentration of nitrogen oxides contained in the exhaust gas, a connecting pipe 64 connecting each of the guide pipes 61 to the analyzer 65, and a suction pump 66 provided in the connecting pipe 64.

[0025] The measurement operation of the NOx measuring instrument 60 is as follows. When any one of the multiple regions 7 is set as the measurement target, the valve 55 corresponding to the one set region 7 is opened, and all other valves 55 are closed. When the suction pump 66 is driven, exhaust gas passing through the region 7 set as the measurement target flows through the guide pipe 61 and into the analysis device 65. This allows the NOx concentration of the exhaust gas flowing through this region 7 to be measured. If any one of the multiple valves 55 is selectively opened to guide the exhaust gas to the analysis device 65, the NOx measuring instrument 60 can measure the NOx concentration in each of the multiple regions 7. This allows the distribution of the NOx concentration in the cross section 6 to be determined.

[0026] The NOx measuring instrument 60 of the present disclosure is not limited to the configuration shown in Fig. 2. The NOx measuring instrument 60 may be configured to irradiate the exhaust gas with a laser beam in each region 7 and receive the laser beam that has passed through the exhaust gas. The NOx concentration in the exhaust gas can be identified by measuring the intensity of the received laser beam. In this case, it is necessary to arrange the optical path piping of the laser beam in the flue 4 so that the space through which the irradiated laser beam passes in the flue 4 is limited to a single region 7.

[0027] Returning to FIG. 1, the measurement result of the NOx measuring instrument 60 is sent to the above-mentioned control device 10. The control device 10 is configured by a computer and includes a processor, a memory (storage medium), and an external communication interface. The processor is a CPU, a GPU, an MPU, a DSP, or a combination thereof. The processor according to other embodiments may be realized by an integrated circuit such as a PLD, an ASIC, an FPGA, or an MCU. The memory is configured to temporarily or non-temporarily store various data, and is realized by at least one of a RAM, a ROM, and a flash memory, for example. The processor executes various control processes according to the instructions of the program loaded into the memory. The control device 10 may be incorporated in a single controller (control panel) constituting the boiler facility 1, or may be a DCS panel constituting one of a plurality of control panels constituting the power plant.

[0028] <Overview of Valve 55 Control> As described above, even if a fluctuation in the boiler load occurs, if the mixture concentration ratio at the inlet 57a of the denitrification reactor 57 is made uniform, the NOx concentration at the cross section 6 will become uniform. In this embodiment, even if the mixture concentration ratio at the inlet 57a becomes temporarily non-uniform after a fluctuation in the boiler load, the mixture concentration ratio at the inlet 57a is made uniform through control of the valve 55. When controlling the valve 55, the opening adjustment response data RD (see FIG. 3) and the load fluctuation NOx distribution data LD (see FIG. 4) are used.

[0029] 3 is a schematic diagram showing opening adjustment response data RD according to an embodiment of the present disclosure. In summary, the opening adjustment response data RD associates an adjustment pattern of the openings of the multiple valves 55 with a change tendency of the NOx concentration occurring in each of the multiple regions 7 constituting the cross-section 6 as a response result when the adjustment pattern is performed. In other words, the opening adjustment response data RD indicates how the NOx concentration distribution in the cross-section 6 changes when the opening of at least one of the multiple valves 55 is adjusted (changed).

[0030] 4 is a schematic diagram of load fluctuation NOx distribution data LD according to an embodiment of the present disclosure. In summary, the load fluctuation NOx distribution data LD indicates the degree of change in NOx concentration that occurs in each of a plurality of regions 7 with a change in boiler load. In other words, the load fluctuation NOx distribution data LD indicates the degree to which the NOx concentration in the cross section 6 changes with a change in boiler load.

[0031] In this embodiment, in order to level out the degree of change in the NOx concentration indicated by the load fluctuation NOx distribution data LD, an opening adjustment pattern that can cause a change tendency opposite to the degree of change is identified from the opening adjustment response data RD. If the identified opening adjustment pattern is reflected in the control of the multiple valves 55, the NOx concentration in the cross section 6 is leveled out.

[0032] Prior to describing the functional configuration of the control device 10 that executes the above-mentioned control, the opening adjustment response data RD and the load fluctuation NOx distribution data LD will be illustrated in detail below.

[0033] <Opening adjustment response data RD> 3, the opening adjustment response data RD includes an opening adjustment pattern that is a pattern for adjusting the opening of at least one of the multiple valves 55. The adjustment (change) of the opening of the valve 55 is a concept that includes increasing the opening, decreasing the opening, and maintaining the opening. The adjustment of the opening of the valve 55 indicated by the opening adjustment pattern does not need to include a specific adjustment amount of the opening.

[0034] The opening adjustment response data RD includes a plurality of the above-mentioned opening adjustment patterns. In Fig. 1, if a plurality of valves 55 are arranged in a row from the front of the paper to the back of the paper in three upper and lower stages, the opening adjustment pattern shown in Fig. 3 is expressed, for example, as follows:

[0035] The opening adjustment pattern "1" may indicate that the opening of only the uppermost valve 55 among all the valves 55 is increased. The opening adjustment pattern "2" may indicate that the opening of only the middle valve 55 among all the valves 55 is increased. The opening adjustment pattern "3" may indicate that the opening of only the valve 55 on the front side of the page among the uppermost valves 55 is decreased. In this way, the opening adjustment pattern includes data indicating adjustment of the opening of at least one of the multiple valves 55.

[0036] Furthermore, the opening adjustment response data RD includes NOx distribution response data indicating a tendency of change in the amount of nitrogen oxides generated in each of the multiple regions 7 of the cross section 6 when the opening of the valve 55 is controlled in accordance with the opening adjustment pattern. The NOx distribution response data is associated with each of the multiple opening adjustment patterns.

[0037] For example, the NOx distribution response data associated with the opening adjustment pattern "1" corresponds to the data surrounded by the two-dot chain line L1. This NOx distribution response data indicates the following (A1), (A2), and (A3). (A1): In all three regions 7 lined up one behind the other on the left side, the NOx concentration increases. (A2): In all three regions 7 arranged in a front-to-back fashion on the left-right central side, the NOx concentration decreases. (A3): In all three regions 7 lined up one behind the other on the right side, the NOx concentration increases.

[0038] Moreover, the NOx distribution response data associated with the opening adjustment pattern "4" corresponds to the data surrounded by the two-dot chain line L4. This NOx distribution response data indicates the following (B1), (B2), and (B3). (B1): Of the three regions 7 arranged in a longitudinal direction on the left side, the NOx concentration increases only in the front region 7, while the NOx concentration does not change in the front-rear central regions 7 and the rear region 7. (B2): Same as (A2). (B3): Same as (A3). Here, "the NOx concentration does not change" is a concept that includes both a case where the change in NOx concentration is zero and a case where the change in NOx concentration is very small.

[0039] The opening adjustment response data RD can be acquired through measurements by the NOx measuring instrument 60 while the boiler 3 is undergoing a test run under a constant load. For example, while the boiler 3 is undergoing a test run so that the boiler load is 100%, the opening of the valve 55 is controlled according to various opening adjustment patterns. If the measurement results of the NOx measuring instrument 60 are acquired while this control is being performed, the opening adjustment response data RD can be generated before the boiler 3 begins commercial operation.

[0040] The opening adjustment response data RD does not have to cover all of the opening adjustment patterns that can be adopted for the multiple valves 55. This is because it is practically difficult to secure time to measure the NOx concentration reflecting all of the opening adjustment patterns for the multiple valves 55 during the test operation of the boiler 3.

[0041] Furthermore, the opening adjustment pattern of the opening adjustment response data RD does not have to be based on the arrangement of the valves 55 shown in Fig. 1. That is, the multiple valves 55 are not limited to being arranged in the horizontal duct portion of the flue 4, and may be arranged in the flue 4 and the vertical duct portion. In any embodiment, the opening adjustment pattern only needs to include multiple patterns for adjusting the opening of the valves 55.

[0042] <Load Fluctuation NOx Distribution Data LD> As shown in Fig. 4, the load fluctuation NOx distribution data LD is data in which the degree of change in NOx concentration caused by the fluctuation in boiler load is assigned to each of a plurality of regions 7 constituting the cross section 6. The example of Fig. 4 shows the load fluctuation NOx distribution data LD when the load of the boiler 3 changes from 100% (full load) to 50% (partial load).

[0043] The load fluctuation NOx distribution data LD can be calculated from pre-load-fluctuation data BD (see FIG. 5) indicating the NOx concentration distribution in the multiple regions 7 while the boiler 3 is operated at full load, and post-load-fluctuation data AD (see FIG. 6) indicating the NOx concentration distribution in the multiple regions 7 while the boiler 3 is operated at partial load. More specifically, the load fluctuation NOx distribution data LD shown in FIG. 4 can be obtained by subtracting the NOx concentration in each of the multiple regions 7 indicated by the pre-load-fluctuation data BD from the NOx concentration in each of the multiple regions 7 indicated by the post-load-fluctuation data AD. Note that "A" on the vertical axis of the graphs in FIG. 5 and FIG. 6 is a value to be used as a guide when comparing the graphs in both figures.

[0044] The pre-load change data BD (see FIG. 5) is generated through the measurement results of the NOx measuring instrument 60 during the test operation of the boiler 3. On the other hand, the post-load change data AD (see FIG. 6) is generated through the measurement results of the NOx measuring instrument 60 after a boiler load change actually occurs during the commercial operation of the boiler 3.

[0045] Moreover, it is preferable that the boiler load indicated by the pre-load-fluctuation data BD is the same as the boiler load when the NOx distribution response data of the opening adjustment response data RD (see FIG. 3) is measured.

[0046] <Basic functions of the control device 10> 7 is a schematic diagram showing a functional configuration of a control device 10 according to an embodiment of the present disclosure. The control device 10 includes a load fluctuation determination unit 16 for determining whether a boiler load has occurred, a first acquisition unit 11 for acquiring load fluctuation NOx distribution data LD when it is determined that a boiler load has occurred, a second acquisition unit 12 for acquiring opening degree adjustment response data RD when it is determined that a boiler load has occurred, and a valve control unit 20 for controlling the opening degree of at least one valve 55.

[0047] As described above, the load change NOx distribution data LD is acquired by calculation using the pre-load change data BD and the post-load change data AD. The pre-load change data BD is stored in advance in a memory constituting the control device 10. The post-load change data AD is specified by the first acquisition unit 11 acquiring the measurement result of the NOx measuring instrument 60 after a boiler load change occurs.

[0048] The opening adjustment response data RD is stored in advance in a memory constituting the control device 10. The second acquisition unit 12 is configured to read out the opening adjustment response data RD from the memory. As described above, the opening adjustment response data RD in this example is based on the premise that the opening of the valve 55 is changed in various ways while the boiler load is a constant load. The memory may store a plurality of opening adjustment response data RD in association with a plurality of boiler loads, respectively. In this case, the second acquisition unit 12 selects the opening adjustment response data RD corresponding to the boiler load before the boiler load fluctuation occurs from the plurality of stored opening adjustment response data RD.

[0049] The valve control unit 20 is configured to control the opening degree of at least one valve 55 based on the load fluctuation NOx distribution data LD and the opening degree adjustment response data RD. The specific control contents are as follows.

[0050] First, the degree of change in NOx concentration occurring in each of the multiple regions 7, which is indicated by the load fluctuation NOx distribution data LD, is identified (see FIG. 4). Then, NOx distribution response data for leveling out the degree of change among the multiple regions 7 is identified from the opening adjustment response data RD. As a specific example, in order to level out the distribution of NOx concentration shown in FIG. 4, it is necessary for the NOx concentration in the multiple regions 7 constituting the cross section 6 to satisfy at least one of the following conditions (C1), (C2), and (C3). (C1): In all three regions 7 arranged one behind the other on the left side, the NOx concentration is maintained. (C2): In all three regions 7 arranged front to back on the left and right central sides, the NOx concentration decreases. (C3): In all three regions 7 arranged one behind the other on the right side, the NOx concentration increases.

[0051] The valve control unit 20 identifies, from the opening adjustment response data RD, NOx distribution response data that satisfies at least one of the conditions (C1) to (C3). For example, in the example of FIG. 3, the two NOx distribution response data enclosed by the two-dot chain lines L1 and L4, respectively, both satisfy (C2) and (C3). The valve control unit 20 identifies the opening adjustment patterns "1" and "4" that correspond to these NOx distribution response data, and controls the opening of the valve 55 according to one of the opening adjustment patterns. In this way, the conditions (C2) and (C3) among (C1) to (C3) are satisfied, and the distribution of the NOx concentration can be expected to be leveled out.

[0052] In addition, when a plurality of opening degree adjustment patterns are specified as described above, a pattern having a smaller pattern number may be preferentially reflected in the control of the valve 55. Alternatively, a pattern that more closely matches the conditions (C1) to (C3) may be selectively adopted among the plurality of opening degree adjustment patterns. In the example of FIG. 3, the opening degree adjustment pattern "4" is more suitable for satisfying (C1) than the opening degree adjustment pattern "1". Therefore, the opening degree adjustment pattern "4" may be preferentially reflected in the control of the valve 55. Regardless of whether the opening degree adjustment pattern "1" or "4" is adopted, the valve control unit 20 gradually increases or decreases the opening degree of at least one valve 55 according to the adopted opening degree adjustment pattern to search for an optimal opening degree of the valve 55.

[0053] The above-described (C1) to (C3) are merely examples. The conditions for leveling out the degree of change in NOx concentration among the multiple regions 7 may be more detailed.

[0054] According to the above configuration, even if the NOx concentration changes among the multiple regions 7 due to the fluctuation of the boiler load, the valve control unit 20 controls the aperture of at least one valve 55 according to the aperture adjustment pattern for leveling the change among the multiple regions 7. Leveling the NOx concentration among the multiple regions 7 means that the ratio between the NOx concentration and the amount of reducing agent in the exhaust gas flowing into the denitrification reactor 57 becomes constant. Therefore, by the valve control unit 20 controlling the valve 55 according to the above aperture adjustment pattern, the mixture concentration ratio can be made uniform in the exhaust gas flowing into the denitrification reactor 57 even if the boiler load fluctuates. In addition, since the mixture concentration ratio can be made uniform without using a model in which the flow state of the exhaust gas is converted into an algorithm, the calculation process executed by the control device 10 can be simplified.

[0055] Additional Components of Controller 10 Returning to FIG. 1 , additional components that may be included in the control device 10 will be described. The control device 10 may further include a first determination unit 13. The first determination unit 13 is configured to determine whether the amount of discharged NOx, which is the amount of nitrogen oxides discharged from the flue 4, falls below a permissible value when the valve control unit 20 is controlled. The amount of discharged NOx may be measured by the above-mentioned NOx measuring instrument 60, or may be measured by another NOx measuring instrument disposed at the outlet of the flue 4. The permissible value may be a value determined in the area in which the boiler equipment 1 is installed, or may be a value set by a designer of the boiler equipment 1.

[0056] Furthermore, the valve control unit 20 gradually increases or decreases the opening of at least one valve 55 according to the above-mentioned specified opening adjustment pattern until it is determined that the amount of exhaust NOx falls below the permissible value. More specifically, if the specified opening adjustment pattern indicates to "increase" the opening of a specific valve 55, the valve control unit 20 gradually and continuously increases the opening of the corresponding valve 55. When the first determination unit 13 eventually determines that the amount of exhaust NOx falls below the permissible value, the valve control unit 20 stops increasing the opening of the valve 55.

[0057] According to the above configuration, even if the amount of discharged NOx exceeds the allowable value due to a change in the boiler load, the valve control unit 20 can identify the opening degree of the valve 55 appropriate for making the amount of discharged NOx below the allowable value. This makes it possible to prevent the reducing agent supplied to the multiple valves 55 from becoming excessive.

[0058] The description of the configuration of the control device 10 will be continued. The control device 10 may further include a load fluctuation acquisition unit 15 configured to acquire the amount of fluctuation in the boiler load. The load fluctuation acquisition unit 15 acquires the amount of fluctuation in the boiler load by acquiring a command (signal) for changing the boiler load issued in the boiler facility 1. For example, if a command is issued to reduce the boiler load to 50% during rated operation of the boiler 3, the load fluctuation acquisition unit 15 acquires 50% as the amount of fluctuation in the boiler load. In addition, the valve control unit 20 decreases the amount of adjustment of the opening degree of the valve 55 as the amount of fluctuation in the boiler load decreases, and increases the amount of adjustment of the opening degree of the valve 55 as the amount of fluctuation in the boiler load increases.

[0059] According to the above configuration, when the amount of fluctuation in the boiler load is relatively small, the valve control unit 20 adjusts the opening degree of the valve 55 by a small amount. This makes it easier to identify the optimal opening degree of the valve 55 for keeping the amount of discharged NOx below the allowable value. On the other hand, when the amount of fluctuation in the boiler load is relatively large, the valve control unit 20 adjusts the opening degree of the valve 55 by a large amount. This makes it possible to shorten the time required to identify the optimal opening degree of the valve 55 for keeping the amount of discharged NOx below the allowable value.

[0060] The description of the configuration of the control device 10 will be continued. The control device 10 may further include a second determination unit 14 for determining whether the amount of exhaust NOx is reduced by controlling the valve 55. The method of acquiring the amount of exhaust NOx is as described above. The valve control unit 20 has a first valve control unit 21 and a second valve control unit 22.

[0061] The first valve control unit 21 is configured to control the opening of the valve 55 according to a first opening adjustment pattern corresponding to the identified first NOx distribution response data when multiple pieces of NOx distribution response data for leveling out the degree of change in the NOx concentration are identified. For example, when the opening adjustment patterns "1" and "4" shown in Fig. 3 are identified, the first valve control unit 21 controls the opening of the valve 55 according to the opening adjustment pattern "1".

[0062] The second valve control unit 22 is configured to control the opening of the valve 55 according to the opening adjustment pattern associated with the identified second NOx distribution response data when the second determination unit 14 determines that the amount of exhaust NOx does not decrease after the first valve control unit 21 starts control. For example, even if the first valve control unit 21 controls the opening of the valve 55 according to the opening adjustment pattern "1", the amount of exhaust NOx may increase due to the influence of (A1) above. In this case, even if the NOx concentration in the cross section 6 becomes uniform, the supply control of the reducing agent according to the opening adjustment pattern is inappropriate. Therefore, in this case, the opening control of the valve 55 by the first valve control unit 21 is stopped, and the second valve control unit 22 executes the control of the opening of the valve 55 according to the opening adjustment pattern "4".

[0063] As described above, the multiple opening adjustment patterns for leveling out the degree of change in NOx concentration caused by fluctuations in boiler load among the multiple regions 7 may include an opening adjustment pattern that is not suitable for reducing the amount of discharged NOx. In this regard, according to the above configuration, when the second determination unit 14 determines that the amount of discharged NOx does not decrease even if the control of the valve 55 is executed according to the first opening adjustment pattern, the control of the valve 55 is executed according to the second opening adjustment pattern instead of the first opening adjustment pattern. This makes it possible to adopt an opening adjustment pattern that is more suitable for reducing the amount of discharged NOx.

[0064] <Denitrification control process> The denitration control process executed by the processor of the control device 10 will be described with reference to Fig. 8. When the denitration control process is started, the boiler 3 is steadily operated at a rated load. The rated load in this example corresponds to a boiler load of 100%. In the following, the processor of the control device 10 may be abbreviated simply as "processor" and "step" may be abbreviated as "S".

[0065] First, the processor determines whether a boiler load fluctuation has occurred (S11). If a load fluctuation signal (load fluctuation command) indicating a boiler load fluctuation is not input to the processor (S11: NO), the processor ends the denitration control process. On the other hand, if a load fluctuation signal is input (S11: YES), the processor acquires the amount of load fluctuation by acquiring the boiler load after the fluctuation indicated by the load fluctuation signal (S13). The processor that executes S11 is an example of the load fluctuation determination unit 16, and the processor that executes S13 is an example of the load fluctuation amount acquisition unit 15.

[0066] Next, the processor acquires load fluctuation NOx distribution data LD (S15), and acquires opening adjustment response data RD (S17). The processor that executes S15 is an example of the first acquisition unit 11, and the processor that executes S17 is an example of the second acquisition unit 12. In this example, in S17, "1" is acquired as the first opening adjustment pattern, and "4" is acquired as the second opening adjustment pattern (see FIG. 3).

[0067] Next, the processor controls the opening of the valve 55 according to the opening adjustment pattern "1" of the two opening adjustment patterns identified in S17 (S19). At this time, the processor increases or decreases the opening of the valve 55 once by the adjustment amount according to the load fluctuation amount acquired in S13.

[0068] Next, the processor judges whether the amount of discharged NOx has decreased (S21). The processor that executes S21 is an example of the second judgment unit 14. If it is judged that the amount of discharged NOx has decreased (S21: YES), the processor judges whether the amount of discharged NOx is below the allowable value (S23). The processor that executes S23 is an example of the first judgment unit 13. If it is judged that the amount of discharged NOx is equal to or greater than the allowable value (S23: NO), the processor continues the opening control of the valve 55 executed in S19 (S27). That is, the control of increasing or decreasing the opening of the valve 55 executed in S19 is additionally executed once more. The processor repeatedly executes S27 until it is judged that the amount of discharged NOx is below the allowable value (S23: NO). When it is judged that the amount of discharged NOx is below the allowable value (S23: YES), the processor ends the denitrification control process. In this case, the processor that executes S19 and S27 is an example of the first valve control unit 21.

[0069] On the other hand, if it is determined that the amount of exhaust NOx does not decrease after the execution of S19 (S21: NO), the processor controls the opening of the valve 55 according to the opening adjustment pattern "4" (S25). More specifically, the opening of the valve 55 is increased or decreased once by the adjustment amount according to the load fluctuation amount acquired in S13. After the execution of S25, the processor returns the process to the above-mentioned S21. If it is determined that the amount of exhaust NOx decreases (S21: YES), the processor repeats the above-mentioned S23 and S27. Then, if it is determined that the amount of exhaust NOx falls below the allowable value (S23: YES), the processor ends the denitrification control process. In this case, the processor that executes S25 and S27 is an example of the second valve control unit 22.

[0070] <Other> The post-load-change data AD at a boiler load of 50% does not have to be directly obtained through the measurement of the NOx measuring instrument 60, and may be estimated by calculation. For example, first load change data (not shown) indicating NOx concentrations in a plurality of regions 7 at a boiler load of 30% is directly obtained in advance through the measurement of the NOx measuring instrument 60. Then, when the boiler load changes from 100% to 50%, the pre-load-change data BD at a boiler load of 50% may be calculated by calculation using the pre-load-change data BD and the first load change data.

[0071] The control device 10 may further include a software module that stores a learning model. In the process of continuous commercial operation of the boiler 3, the arithmetic processing executed by each of the first acquisition unit 11, the second acquisition unit 12, and the valve control unit 20 may be accumulated as teacher data, and machine learning may be performed on the learning model based on the teacher data. The learning model that has completed the machine learning acquires at least the load fluctuation amount as input data. After acquiring the input data, the learning model outputs the valve 55 that should be controlled in opening degree among the multiple valves 55 and the specific opening degree that should be set for the valve 55 as output data. After such a learning model is constructed, control by the first acquisition unit 11, the second acquisition unit 12, and the valve control unit 20 can be eliminated.

[0072] <Summary> The contents described in the above-mentioned embodiments can be understood, for example, as follows.

[0073] 1) A control device (10) according to at least one embodiment of the present disclosure includes: A control device (10) configured to control an opening degree of each of a plurality of valves (55) for adjusting an amount of a reducing agent supplied to an exhaust gas discharged from a boiler (3), a first acquisition unit (11) for acquiring load fluctuation NOx distribution data (LD) in which a degree of change in the amount of nitrogen oxides caused by a change in boiler load is assigned to each of a plurality of regions (7) constituting a cross section (6) of the flue (4) through which the exhaust gas flows; a second acquisition unit (12) for acquiring opening adjustment response data (RD) in which a plurality of opening adjustment patterns, which are patterns for adjusting the opening of at least one of the plurality of valves, are associated in advance with a plurality of NOx distribution response data indicating a tendency of change in the amount of nitrogen oxide generated in each of the plurality of regions in response to the opening adjustment of the at least one valve; a valve control unit (20) for identifying, from the opening degree adjustment response data, NOx distribution response data for leveling out the degree of change in the amount of nitrogen oxide occurring in each of the plurality of regions indicated by the load fluctuation NOx distribution data, and for controlling the opening degree of the at least one valve in accordance with the opening degree adjustment pattern associated with the identified NOx distribution response data; Equipped with.

[0074] According to the above configuration 1), even if the amount of nitrogen oxides varies among the multiple regions due to fluctuations in the boiler load, the valve control unit controls the aperture of at least one valve according to an aperture adjustment pattern for leveling out the variation among the multiple regions. Leveling out the amount of nitrogen oxides among the multiple regions means that the ratio of the amount of nitrogen oxides to the amount of reducing agent in the exhaust gas flowing into the denitration container becomes constant. Therefore, by the valve control unit controlling the valve according to the above aperture adjustment pattern, the ratio of the amount of nitrogen oxides to the amount of reducing agent in the exhaust gas flowing into the denitration container can be made uniform even if the boiler load varies. In addition, since the above ratio can be made uniform without using a model that represents the flow state of the exhaust gas as an algorithm, the calculation process performed by the control device can be simplified.

[0075] 2) In some embodiments, the control device according to 1) above, The flue gas control device further includes a first determination unit (13) for determining whether an amount of nitrogen oxide discharged from the flue is below a permissible value when the valve control unit is controlled, The valve control unit gradually adjusts the opening of the at least one valve according to the opening adjustment pattern until it is determined that the amount of nitrogen oxides discharged falls below the permissible value.

[0076] According to the configuration of 2) above, even if the amount of nitrogen oxide discharged exceeds the allowable value due to a change in the boiler load, the valve control unit can identify the valve opening degree appropriate for keeping the amount of nitrogen oxide discharged below the allowable value. This makes it possible to prevent the reducing agent supplied to the multiple valves from becoming excessive.

[0077] 3) In some embodiments, the control device according to 2) above, The boiler load control system further includes a load fluctuation acquisition unit (15) configured to acquire a fluctuation amount of the boiler load, The valve control unit is configured to reduce the adjustment amount of the opening of the at least one valve as the fluctuation amount of the boiler load is smaller, and to increase the adjustment amount of the opening of the at least one valve as the fluctuation amount of the boiler load is larger.

[0078] According to the configuration of 3) above, when the fluctuation amount of the boiler load is relatively small, the valve opening adjustment amount by the valve control unit is small. This makes it easier to identify the optimal valve opening amount for keeping the amount of nitrogen oxide emissions below the allowable value. On the other hand, when the fluctuation amount of the boiler load is relatively large, the valve opening adjustment amount by the valve control unit is large. This makes it possible to shorten the time required to identify the optimal valve opening amount for keeping the amount of nitrogen oxide emissions below the allowable value.

[0079] 4) In some embodiments, the control device according to 1) or 3) above, a second determination unit (14) for determining whether an amount of exhaust nitrogen oxides, which is the amount of the nitrogen oxides exhausted from the flue, is reduced by control of the valve control unit, The valve control unit is a first valve control unit (20) for controlling an opening degree of the at least one valve in accordance with a first opening degree adjustment pattern associated with a first identified NOx distribution response data when a plurality of pieces of NOx distribution response data for leveling out the degree of change in the amount of nitrogen oxides are identified; a second valve control unit (20) for controlling an opening degree of the at least one valve in accordance with a second opening degree adjustment pattern associated with the specified second NOx distribution response data when the second determination unit determines that the amount of exhaust nitrogen oxides has not decreased after the start of control of the first valve control unit; Includes.

[0080] According to the inventor's findings, the multiple opening adjustment patterns for leveling out the degree of change in the amount of nitrogen oxides caused by fluctuations in the boiler load among multiple regions may include an opening adjustment pattern that is not suitable for reducing the amount of nitrogen oxides discharged. In this regard, according to the configuration of 4) above, when the second determination unit determines that the amount of nitrogen oxides discharged does not decrease even if the valve control is performed according to the first opening adjustment pattern, valve control is performed according to the second opening adjustment pattern instead of the first opening adjustment pattern. This makes it possible to adopt an opening adjustment pattern that is more suitable for reducing the amount of nitrogen oxides discharged.

[0081] 5) At least one embodiment of the denitrification device (5) according to the present disclosure includes: A control device (10) according to any one of 1) to 4) above; a plurality of reducing agent nozzles (51) configured to inject the reducing agent into the exhaust gas flowing through the flue gas passage; a plurality of reducing agent supply passages (52) for supplying the reducing agent to each of the plurality of reducing agent nozzles; the plurality of valves (55) arranged in the plurality of reducing agent supply paths, respectively; a denitration reactor (57) including a denitration catalyst, the denitration reactor (57) being disposed downstream of the plurality of reducing agent nozzles in the flue; Equipped with.

[0082] According to the above configuration 5), the same technical advantages as those of the above configuration 1) can be obtained.

[0083] 6) The boiler facility (1) according to at least one embodiment of the present disclosure is A boiler (3), a flue (4) through which exhaust gas generated in the boiler flows; a denitration device (5) according to 5) above for denitrifying the exhaust gas flowing through the flue; Equipped with.

[0084] According to the above configuration 6), the same technical advantage as that of the above configuration 1) can be obtained. [Explanation of symbols]

[0085] 1: Boiler equipment 3: Boiler 4: Flue 5:Denitration equipment 6: Cross section 7 :Area 9: Air heater 10: Control device 11:First acquisition part 12:Second acquisition part 13:1st judgment part 14:Second judgment part 15: Load fluctuation acquisition section 16: Load fluctuation judgment section 20: Valve control section 21: First valve control section 22: Second valve control section 51: Reducing agent nozzle 52: Reducing agent supply channel 55: Valve 57:Denitrification reactor 57a: Entrance 57b: Exit 59: Storage section 60: NOx measuring instrument 61: Guide tube 62: Opening and closing valve 64: Connecting pipe 65: Analyzer 66: Suction pump AD: Data after load change BD: Data before load change LD: Load fluctuation NOx distribution data RD: Opening adjustment response data

Claims

1. A control device configured to control an opening degree of each of a plurality of valves for adjusting a supply amount of a reducing agent to an exhaust gas discharged from a boiler, A first acquisition unit for acquiring load fluctuation NOx distribution data in which a degree of change in the amount of nitrogen oxides caused by a change in boiler load is assigned to each of a plurality of regions constituting a cross section of the flue through which the exhaust gas flows; a second acquisition unit for acquiring opening adjustment response data in which a plurality of opening adjustment patterns, which are patterns for adjusting an opening of at least one of the plurality of valves, are associated in advance with a plurality of NOx distribution response data indicating a tendency of a change in the amount of nitrogen oxide generated in each of the plurality of regions in response to the opening adjustment of the at least one valve; a valve control unit that identifies, from the opening degree adjustment response data, the NOx distribution response data for leveling out the degree of change in the amount of nitrogen oxide occurring in each of the plurality of regions indicated by the load fluctuation NOx distribution data, and controls the opening degree of the at least one valve in accordance with the opening degree adjustment pattern associated with the identified NOx distribution response data; A control device comprising:

2. A first determination unit is further provided for determining whether an amount of exhaust nitrogen oxides, which is the amount of the nitrogen oxides exhausted from the flue, is below a permissible value when the valve control unit is controlled, The valve control unit gradually adjusts the opening of the at least one valve according to the opening adjustment pattern until it is determined that the amount of exhaust nitrogen oxides is below the permissible value. The control device according to claim 1 .

3. A load fluctuation acquisition unit configured to acquire a fluctuation amount of the boiler load, The valve control unit is configured to reduce an adjustment amount of the opening degree of the at least one valve as the fluctuation amount of the boiler load is smaller, and to increase an adjustment amount of the opening degree of the at least one valve as the fluctuation amount of the boiler load is larger. The control device according to claim 2.

4. A second determination unit is further provided for determining whether an amount of exhaust nitrogen oxides, which is the amount of the nitrogen oxides exhausted from the flue, is reduced by control of the valve control unit, The valve control unit is a first valve control unit for controlling an opening degree of the at least one valve in accordance with a first opening degree adjustment pattern associated with a first identified NOx distribution response data when a plurality of NOx distribution response data for leveling out the degree of change in the amount of nitrogen oxides are identified; a second valve control unit for controlling an opening degree of the at least one valve in accordance with a second opening degree adjustment pattern associated with the specified second NOx distribution response data when the second determination unit determines that the amount of exhaust nitrogen oxides does not decrease after the start of control of the first valve control unit; Includes A control device according to any one of claims 1 to 3.

5. A control device according to any one of claims 1 to 3; a plurality of reducing agent nozzles configured to inject the reducing agent into the exhaust gas flowing through the flue; a plurality of reducing agent supply passages for supplying the reducing agent to each of the plurality of reducing agent nozzles; the plurality of valves disposed in the plurality of reducing agent supply paths, respectively; a denitration reactor including a denitration catalyst disposed downstream of the plurality of reducing agent nozzles in the flue; A denitrification device equipped with the above structure.

6. Boiler and a flue through which exhaust gas generated in the boiler flows; A denitration device according to claim 5 for denitrifying the exhaust gas flowing through the flue gas passage; A boiler facility equipped with:

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