Incineration device

Abstract

To provide an incineration device capable of efficiently preventing corrosion of a waste heat boiler heat transfer pipe.SOLUTION: An incineration device 1 includes: an incinerator 10; a secondary combustion chamber 27; a waste heat boiler 20 having a waste heat boiler heat transfer pipe 21 exposed into a flue; a dust collecting device 40 that collects an ash content in combustion gas downstream of the waste heat boiler 20; a first addition section 51 that adds an additive including sulfur or a sulfur compound in the waste heat boiler 20 or upstream of the waste heat boiler 20; a second addition section 52 that adds an acidic gas treatment agent between the waste heat boiler 20 and the dust collecting device 40; and a control section 50 that controls the first addition section 51 and the second addition section 52. The control section 50 executes first control for adding the acidic gas treatment agent on the basis of a hydrogen chloride concentration and a sulfur oxide concentration in the combustion gas downstream of the first addition section 51, and switches the control to second control for adding the additive including sulfur or a sulfur compound and a predetermined amount of the acidic gas treatment agent in a predetermined condition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an incineration apparatus. [Background technology]

[0002] The waste heat boiler installed in the incineration system recovers the heat of the combustion gas generated by the incineration of the materials to be incinerated. When the materials to be incinerated contain chlorine compounds, the combustion of the materials generates gases derived from hydrogen chloride, heavy metals, and alkali chlorides, and these gases cause deposits containing chlorides to adhere to the surface of the waste heat boiler heat transfer tubes installed in the flue of the waste heat boiler, resulting in corrosion of the waste heat boiler heat transfer tubes.

[0003] Patent Document 1 describes a method for operating an incineration plant in which sulfur compounds are intermittently added (coexisted) at a higher concentration than the combustion atmosphere of the material to be incinerated in order to prevent corrosion of the heat transfer tubes of a waste heat boiler. The chlorides contained in the deposits react with the sulfur compounds to produce sulfates, which makes it possible to reduce the deposits that cause corrosion of the heat transfer tubes of the waste heat boiler. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-303743 Summary of the Invention [Problem to be solved by the invention]

[0005] The addition of sulfur compounds generates sulfates, and at the same time, acidic gases (such as hydrogen chloride gas and sulfur oxide gases) that are subject to emission regulations are generated. Combustion gases containing these gases are released as exhaust gas after being removed from the atmosphere by a dust collector, and therefore their concentrations must be reduced by adding an acidic gas treatment agent. In the incineration system operating method described in Patent Document 1, sulfur compounds are added intermittently, so the acidic gas concentration temporarily increases each time the sulfur compounds are added. However, Patent Document 1 does not describe a method for adding an acidic gas treatment agent to treat acidic gases whose concentrations have temporarily increased.

[0006] Furthermore, in a control system that measures the concentration of acid gases contained in exhaust gas and then adjusts the amount of acid gas treatment agent added, the intermittent addition of sulfur compounds could cause the acid gas concentration in the exhaust gas to temporarily exceed the emission regulation value. Therefore, the sulfur compounds had to be added in small amounts while checking the concentrations of hydrogen chloride gas and sulfur oxide gas in the exhaust gas, which made it impossible to effectively prevent corrosion of the waste heat boiler heat transfer tubes.

[0007] Therefore, there is a demand for an incineration apparatus that can efficiently prevent corrosion of the heat transfer tubes of the waste heat boiler. [Means for solving the problem]

[0008] The incineration apparatus according to the present invention is characterized by comprising: an incinerator for incinerating materials containing chlorine compounds; a secondary combustion chamber for generating combustion gas downstream of the incinerator; a waste heat boiler having waste heat boiler heat transfer tubes exposed in a flue; a dust collector for collecting ash from the combustion gas downstream of the waste heat boiler; a first adding unit for adding an additive containing sulfur or a sulfur compound in the waste heat boiler or upstream of the waste heat boiler; a second adding unit for adding an acid gas treatment agent between the waste heat boiler and the dust collector; and a control unit for controlling the operation of the first adding unit and the second adding unit, wherein the control unit executes a first control for adding the acid gas treatment agent based on the hydrogen chloride concentration and / or sulfur oxide concentration in the combustion gas downstream of the first adding unit, and switches to a second control under predetermined conditions for adding the additive containing sulfur or a sulfur compound and a predetermined amount of the acid gas treatment agent.

[0009] According to this configuration, when adding an additive containing sulfur or a sulfur compound under predetermined conditions, the first control, which adds an acid gas treatment agent based on the hydrogen chloride concentration and / or sulfur oxide concentration in the combustion gas downstream of the first addition section, is switched to the second control, which adds a predetermined amount of acid gas treatment agent. Here, the predetermined amount of acid gas treatment agent refers to an amount of acid gas treatment agent that sufficiently exceeds the amount of acid gas treatment agent required to neutralize the hydrogen chloride gas and sulfur oxide gas generated by the addition of the additive containing sulfur or a sulfur compound. This ensures that a sufficient amount of acid gas treatment agent is present in the hydrogen chloride gas and sulfur oxide gas, thereby efficiently promoting the neutralization reaction of the hydrogen chloride gas and sulfur oxide gas. Therefore, even if hydrogen chloride gas and sulfur oxide gas are generated in the combustion gas by adding the additive containing sulfur or a sulfur compound, the hydrogen chloride concentration and sulfur oxide concentration in the exhaust gas do not increase rapidly. Therefore, compared to, for example, adding an additive containing sulfur or a sulfur compound and then adding an acid gas treatment agent according to the hydrogen chloride concentration or sulfur oxide concentration in the combustion gas, the acid gas treatment agent required for the neutralization reaction can be added in advance, which makes it possible to avoid a situation in which the hydrogen chloride concentration or sulfur oxide concentration rises suddenly and the acid gas treatment agent required for the neutralization reaction becomes insufficient, and makes it possible to prevent these concentrations from temporarily exceeding the emission regulation values.

[0010] Furthermore, because emission regulations vary from one municipality to another, optimizing the amount and timing of addition of additives containing sulfur or sulfur compounds for each municipality makes it possible to more efficiently suppress corrosion of the waste heat boiler heat transfer tubes of each incineration device.

[0011] Another characteristic configuration is that the present invention further includes a measuring unit that measures at least one of the hydrogen chloride concentration and the sulfur oxide concentration in the combustion gas downstream of the first adding unit, and the predetermined condition is a case where the measurement value measured by the measuring unit is smaller than a predetermined reference value.

[0012] According to this configuration, when the measured values ​​of the hydrogen chloride concentration and sulfur oxide concentration in the combustion gas are lower than predetermined reference values, the control unit switches from the first control to the second control. According to this configuration, when the measured values ​​are equal to or higher than the predetermined reference values, the first control is executed and no additive containing sulfur or a sulfur compound is added, thereby preventing a sudden increase in the hydrogen chloride concentration and sulfur oxide concentration in the exhaust gas. Furthermore, when the measured values ​​are lower than the predetermined reference values, the control unit switches to the second control and adds an additive containing sulfur or a sulfur compound and a predetermined amount of acid gas treatment agent, thereby suppressing a sudden increase in the hydrogen chloride concentration and sulfur oxide concentration in the combustion gas by the acid gas treatment agent. Therefore, in either case, the hydrogen chloride concentration and sulfur oxide concentration in the exhaust gas do not exceed the emission reference values. This makes it possible to optimize the amount and timing of the additive containing sulfur or a sulfur compound to be added, thereby efficiently preventing corrosion of the waste heat boiler heat transfer tubes.

[0013] Another characteristic configuration is that the dust collector further includes a measurement unit that measures at least one of the hydrogen chloride concentration and the sulfur oxide concentration in the combustion gas downstream of the first addition unit, a memory unit that stores the measurement values ​​of the hydrogen chloride concentration and / or the sulfur oxide concentration measured by the measurement unit, and a calculation unit that calculates a predicted value of the hydrogen chloride concentration and / or the sulfur oxide concentration in the exhaust gas discharged from the dust collector, and the predetermined condition is a case where the predicted value calculated by the calculation unit is smaller than a predetermined reference value.

[0014] According to this configuration, when the predicted values ​​of the hydrogen chloride concentration and sulfur oxide concentration in the exhaust gas discharged from the dust collector are lower than predetermined reference values, the control unit switches from the first control to the second control. This allows the first control to be executed when the predicted values ​​are equal to or higher than the predetermined reference values, thereby preventing the addition of an additive containing sulfur or a sulfur compound, and thus preventing a sudden increase in the hydrogen chloride concentration and sulfur oxide concentration in the exhaust gas. Furthermore, when the predicted values ​​are lower than the predetermined reference values, the control unit switches to the second control, adding an additive containing sulfur or a sulfur compound and a predetermined amount of acid gas treatment agent. This prevents a sudden increase in the hydrogen chloride concentration and sulfur oxide concentration in the combustion gas by the acid gas treatment agent. Therefore, in either case, the hydrogen chloride concentration and sulfur oxide concentration in the exhaust gas do not exceed the emission reference values. This allows the amount and timing of the additive containing sulfur or a sulfur compound to be optimized, thereby efficiently preventing corrosion of the waste heat boiler heat transfer tubes.

[0015] Furthermore, by providing a measurement unit that measures the hydrogen chloride concentration and / or sulfur oxide concentration contained in the exhaust gas downstream of the dust collector and a memory unit that stores these measurement values, the calculation unit can calculate a predicted value based on the measurement values. This allows for accurate switching from the first control to the second control based on past performance, and makes it possible to optimize the amount and timing of addition of the additive containing sulfur or a sulfur compound.

[0016] Another characteristic configuration is that the calculation unit calculates an average value of each of the measurement values ​​in a predetermined first time period and the predicted value of the hydrogen chloride concentration and / or the sulfur oxide concentration in the flue gas discharged from the dust collector after a predetermined second time period based on the average value.

[0017] According to this configuration, the calculation unit calculates an average value of the measured values ​​of the hydrogen chloride concentration and / or the sulfur oxide concentration during a predetermined first time period, and calculates a predicted value based on this average value. Therefore, switching from the first control to the second control can be performed with high accuracy based on the actual results during the predetermined first time period, and it becomes possible to optimize the amount and timing of addition of the additive containing sulfur or a sulfur compound.

[0018] Another characteristic feature is that the first adding section adds the additive containing sulfur or a sulfur compound to the secondary combustion chamber.

[0019] According to this configuration, by adding an additive containing sulfur or a sulfur compound to the secondary combustion chamber, the additive remains in the secondary combustion chamber and can react sufficiently with the combustion gas, thereby reducing the chloride concentration in the fly ash and suppressing corrosion of the heat transfer tubes of the waste heat boiler.

[0020] Another characteristic feature is that the first adding unit adds the additive containing sulfur or a sulfur compound in the incinerator.

[0021] According to this configuration, by adding an additive containing sulfur or a sulfur compound to an incinerator where the temperature of the combustion gas is high, it is possible to reduce chlorides adhering to the heat transfer tubes of the waste heat boiler, thereby suppressing corrosion of the heat transfer tubes of the waste heat boiler.

[0022] Another characteristic feature is that in the second control, the control unit starts adding the predetermined amount of the acid gas treatment agent after a predetermined time has elapsed after starting to add the additive containing sulfur or a sulfur compound.

[0023] According to this configuration, the acid gas treatment agent can be added at the timing when the hydrogen chloride concentration or sulfur oxide concentration starts to increase, which makes it possible to optimize the amount of acid gas treatment agent used and to efficiently cause the neutralization reaction.

[0024] Another characteristic feature is that the additive containing sulfur or a sulfur compound is sulfuric acid.

[0025] According to this configuration, sulfates can be efficiently produced by using sulfuric acid as an additive containing sulfur or a sulfur compound. In addition, since sulfuric acid is a liquid, the additive can be easily handled.

[0026] Another characteristic feature is that the control unit activates the first addition unit to add the sulfuric acid when the temperature of the combustion gas in the vicinity of the secondary combustion chamber is equal to or higher than a specified value.

[0027] According to this configuration, it is possible to suppress a (sudden) drop in the combustion gas temperature caused by the endothermic action of sulfuric acid, and to maintain a temperature at which harmful substances such as dioxins can be sufficiently decomposed.

[0028] Another characteristic feature is that the dust collector further includes a backwashing device that brushes off fly ash adhering to the dust collector, and a backwashing device control unit that controls the backwashing device in conjunction with the control unit's switching between the first control and the second control.

[0029] According to this configuration, by controlling the backwash device in conjunction with switching between the first control and the second control, for example, the operation timing of the backwash device can be optimized so that the backwash device is not operated during the second control and the unreacted acid gas treatment agent attached to the inside of the dust collector is allowed to react with the combustion gas flowing into the dust collector, thereby making it possible to effectively utilize the acid gas treatment agent in the fly ash attached to the dust collector. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a diagram showing the overall configuration of an incineration apparatus. [Figure 2] FIG. 4 is a flow diagram relating to switching between first control and second control. [Figure 3] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, an embodiment of the incineration apparatus according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications are possible without departing from the spirit of the invention.

[0032] [Overall structure] As shown in FIG. 1, the incineration apparatus 1 includes an incinerator 10, a waste heat boiler 20, a steam turbine generator 30, a dust collector 40, and a chimney 60.

[0033] In this embodiment, the incinerator 10 is configured as a rotary stoker-type incinerator in which the furnace body 11 is cylindrical and rotates around its axis. The furnace body 11 has an inlet 11a for the material to be incinerated W on the upstream side and an outlet 11b for the material to be incinerated W on the downstream side. The axis of the furnace body 11 is inclined relative to the horizontal so that the inlet 11a is higher than the outlet 11b. The furnace body 11 is formed using a metal such as carbon steel. The material to be incinerated W corresponds to sludge, garbage, etc. containing chlorine compounds.

[0034] The furnace body 11 is housed in a cover casing 12. A plurality of water pipes 13 extending along the axial direction are provided in the furnace body 11 at predetermined intervals in the circumferential direction. Metallic fins 14 extending along the axial direction are provided between two water pipes 13 adjacent to each other along the circumferential direction. Therefore, the water pipes 13 and the fins 14 are arranged alternately along the circumferential direction. The fins 14 have a plurality of air holes 15 penetrating in the radial direction. These water pipes 13 and fins 14 form a fire grate.

[0035] The furnace body 11 is provided with rotation transmission members (not shown) on the inlet 11a side and outlet 11b side of the furnace body 11, and these rotation transmission members are configured to be rotatable around their axis by a driving device (not shown). The furnace body 11 rotates in response to this rotation.

[0036] A hopper 5 is provided on the inlet 11a side of the furnace body 11. The materials to be incinerated W put into the hopper 5 are supplied to the furnace body 11 by a dust feeder 6. In this embodiment, the dust feeder 6 is of a pusher type.

[0037] A plurality of wind boxes 25 are provided below the furnace body 11, and communicate with the lower end of the cover casing 12. The primary gas (e.g., air) supplied to the wind boxes 25 is introduced into the furnace body 11 from the bottom of the furnace body 11 through the air holes 15. The amount of primary gas supplied to the furnace body 11 and the proportion of primary gas supplied to each combustion area in the furnace body 11 can be adjusted using the rotation speed of the forced draft fan and a flow control device (not shown) such as a damper. The amount of primary gas supplied and the proportion of primary gas supplied to each combustion area in the furnace body 11 can be changed depending on, for example, the composition, amount, and distribution of the material to be incinerated W in the furnace body 11.

[0038] The incineration material W is supplied into the furnace body 11 while the incinerator 10 is rotating at a low speed. The incineration material W supplied to the furnace body 11 is stirred by the rotation of the furnace body 11 and gradually moves downstream. Furthermore, while the incineration material W moves through the furnace body 11, primary gas is introduced into the furnace body 11 from the wind box 25. It is preferable to set the amount of primary gas supplied to maintain slow combustion of the incineration material W. During slow combustion, unburned gas is generated, and this unburned gas is introduced into the secondary combustion chamber 27 located downstream of the furnace body 11. A secondary gas, such as air, is supplied to the secondary combustion chamber 27 together with the unburned gas. This combusts the unburned gas. Furthermore, unburned components contained in the ash of the incineration material W discharged from the furnace body 11 are combusted in the post-combustion device 28.

[0039] The waste heat boiler 20 is provided downstream of and connected to the secondary combustion chamber 27, and generates steam by utilizing the heat of the combustion gas discharged from the furnace, post-combustion chamber 29, and secondary combustion chamber 27. The waste heat boiler 20 has waste heat boiler heat transfer tubes 21 exposed in the flue. Water is supplied to the waste heat boiler 20 from the water supply device 8, and steam is generated by heat exchange with the combustion gas.

[0040] The steam turbine generator 30 is supplied with steam generated by the waste heat boiler 20, which drives a turbine to generate electricity. The combustion gas from which heat has been recovered in the waste heat boiler 20 is cooled and subjected to dust removal treatment by a dust collector 40, such as a bag filter, installed on the combustion gas route between the waste heat boiler 20 and the chimney 60, before being discharged to the outside of the system via the chimney 60. The fly ash from which dust has been removed in the waste heat boiler 20 or the dust collector 40, etc., is returned to the incinerator 10 by a fly ash return conveyor 48 and may be incinerated again together with the materials W to be incinerated.

[0041] The water supply system 8 includes a condenser that cools and condenses the low-pressure wet steam discharged from the turbine outlet of the steam turbine generator 30, thereby returning it to saturated water and storing it, and a deaerator that degasses the saturated water that is returned from the condenser to the waste heat boiler 20 by a pump.

[0042] The incineration apparatus 1 of this embodiment is equipped with a first addition section 51 that adds an additive containing sulfur or a sulfur compound to the combustion gas flow passage downstream of the incinerator 10. More specifically, the first addition section 51 is arranged to add an additive containing sulfur or a sulfur compound to the secondary combustion chamber 27. Because the incineration target material W contains chlorine compounds, when fly ash containing chlorides such as metal chlorides generated by combustion adheres to the surface of the waste heat boiler heat transfer tubes 21, the deposits are oxidized and chlorinated, causing corrosion of the waste heat boiler heat transfer tubes 21. Therefore, by adding an additive containing sulfur or a sulfur compound to the secondary combustion chamber 27 and allowing it to react with the chlorides in the combustion gas, corrosion of the waste heat boiler heat transfer tubes 21 can be reduced.

[0043] The additive containing sulfur or a sulfur compound may be, for example, sulfur or sulfuric acid. In particular, sulfuric acid is liquid and therefore easy to handle, allowing the configuration of the incineration apparatus 1 to be simplified. The first adding unit 51 may also have a nozzle for adding the additive containing sulfur or a sulfur compound, a pump for pressure-feeding the additive, or the like, and the configuration of the apparatus is not particularly limited.

[0044] When an additive containing sulfur or a sulfur compound is added by the first adding unit 51, sulfates are produced and hydrogen chloride gas and sulfur oxide gas are also produced at the same time. The combustion gas containing hydrogen chloride gas and sulfur oxide gas is discharged as exhaust gas from the dust collector 40. Each municipality in which the incinerator 1 is installed sets emission control values ​​for the hydrogen chloride and sulfur oxide contained in the exhaust gas. Therefore, the incinerator 1 is equipped with a second adding unit 52 that adds an acid gas treatment agent to remove hydrogen chloride and sulfur oxides from the exhaust gas. The second adding unit 52 is provided in the combustion gas flow path between the waste heat boiler 20 and the dust collector 40.

[0045] The second adding section 52 supplies an acid gas treatment agent, such as baking soda, slaked lime, caustic soda, or dolomite, dispersed in the combustion gas. As a result, hydrogen chloride gas and sulfur oxide gases in the combustion gas are neutralized and removed by the acid gas treatment agent. The reaction products produced by this neutralization reaction are sent to the dust collector 40 along with the combustion gas flow, and are separated from the combustion gas together with fly ash and soot by the dust collection process in the dust collector 40.

[0046] The operation of the first addition unit 51 and the second addition unit 52 is controlled by the control unit 50. The control unit 50 is equipped with a processor, and causes a memory unit (not shown) and a calculation unit (not shown) to function. The processor includes an ASIC, FPGA, CPU, or other hardware for executing applications stored in the memory unit (the same applies hereinafter). The control mode by the control unit 50 will be described below.

[0047] [Control mode of incineration device] The control unit 50 switches between the first control and the second control to control the operation of the first addition unit 51 and the second addition unit 52. First, the first control will be described. In the first control, the control unit 50 controls the second addition unit 52 to add the acid gas treatment agent based on the concentrations of hydrogen chloride and sulfur oxides contained in the combustion gas.

[0048] The concentrations of hydrogen chloride and sulfur oxides contained in the combustion gas are measured by the measurement unit 54. The measurement unit 54 is disposed downstream of the first addition unit 51 and upstream of the second addition unit 52. Specifically, the measurement unit 54 measures the hydrogen chloride concentration and the sulfur oxide concentration. The measured hydrogen chloride concentration X0 and the measured sulfur oxide concentration Y0 measured by the measurement unit 54 may be stored in the memory unit. In the first control, for example, the control unit 50 acquires these measured values ​​X0 and Y0 from the memory unit and compares them in the calculation unit with a predetermined reference value X for the hydrogen chloride concentration and a predetermined reference value Y for the sulfur oxide concentration of the combustion gas that can be discharged from the chimney 60. If the measured value X0 exceeds the predetermined reference value X or if the measured value Y0 exceeds the predetermined reference value Y, the control unit 50 controls the second addition unit 52 to add the acid gas treatment agent so that the hydrogen chloride concentration and the sulfur oxide concentration in the combustion gas become lower than the predetermined reference values ​​X and Y. The amount of acid gas treatment agent to be added may be the amount necessary to neutralize hydrogen chloride and sulfur oxides, and may be calculated in the calculation unit based on the measured values ​​X0 and Y0, or may be calculated based on average values ​​X1 and Y1 of the measured values ​​X0 and Y0 over a certain period of time. The predetermined standard values ​​X and Y may be set lower than the emission regulation values ​​for hydrogen chloride and sulfur oxide gases in each local government where the incineration apparatus 1 is installed, for example.

[0049] The measuring unit 54 may be disposed downstream of the second adding unit 52. The location of the measuring unit 54 is not important as long as it can measure the concentrations of hydrogen chloride and sulfur oxides contained in the combustion gas before it is discharged from the chimney 60.

[0050] In the second control, the control unit 50 controls the operation of the first and second adding units 51 and 52 so that the addition of the sulfur or sulfur compound-containing additive to the secondary combustion chamber 27 and the addition of a predetermined amount of acid gas treatment agent to the combustion gas are performed at approximately the same time. The predetermined amount of acid gas treatment agent is an amount that sufficiently exceeds the amount of acid gas treatment agent required to neutralize the hydrogen chloride and sulfur oxide gases generated by the addition of the sulfur or sulfur compound-containing additive. The predetermined amount of acid gas treatment agent may be, for example, 1 to 200 kg / ton of waste. This ensures that the amount of acid gas treatment agent is sufficient to counteract the hydrogen chloride and sulfur oxide gases generated by the addition of the sulfur or sulfur compound-containing additive, thereby allowing the neutralization reaction to proceed efficiently. The measured values ​​X0 and Y0 measured by the measurement unit 54 are expected to vary irregularly due to the addition of the sulfur or sulfur compound-containing additive by the first adding unit 51. Therefore, if the amount of acid gas treatment agent to be added is determined based on the measured values ​​X0 and Y0, it may not be possible to keep up with the sudden increase in hydrogen chloride and sulfur oxide concentrations, and the emission regulation values ​​may be temporarily exceeded. Therefore, by adding an additive containing sulfur or a sulfur compound and a predetermined amount of acid gas treatment agent at approximately the same time in the second control, it is possible to prevent the emission regulation values ​​from being temporarily exceeded.

[0051] The timing of adding the predetermined amount of acid gas treatment agent may be simultaneous with the timing of adding the additive containing sulfur or a sulfur compound, or may be before or after the addition of the additive. The timing of adding the predetermined amount of acid gas treatment agent may also be determined based on the measured hydrogen chloride concentration value X0 and the measured sulfur oxide concentration value Y0 measured by the measurement unit 54. For example, the predetermined amount of acid gas treatment agent may be added when the rate of increase of the measured values ​​X0 and Y0 exceeds a certain value.

[0052] Next, switching between the first control and the second control will be described with reference to Fig. 2. Fig. 2 is a flow diagram showing switching between the first control and the second control. The control unit 50 performs the first control in a steady state.

[0053] First, the control unit 50 acquires the measured hydrogen chloride concentration X0 and the measured sulfur oxide concentration Y0 measured by the measurement unit 54 and stores them in the memory unit (step #01 in FIG. 2 ). Then, the calculation unit calculates the average hydrogen chloride concentration X1 and the average sulfur oxide concentration Y1 for a predetermined first time period (step #02 in FIG. 2 ). The predetermined first time period may be, for example, 30 minutes or 1 hour. Then, the control unit 50 calculates the predicted hydrogen chloride concentration X3 and the predicted sulfur oxide concentration Y3 for a predetermined second time period by adding the predicted increase X2 in the hydrogen chloride concentration or the predicted increase Y2 in the sulfur oxide concentration due to the addition of the additive containing sulfur or a sulfur compound to the average values ​​X1 and Y1, respectively (step #03 in FIG. 2 ). The predicted increases X2 and Y2 may be based on the actual increase in the hydrogen chloride concentration or the sulfur oxide concentration due to the addition of the additive containing sulfur or a sulfur compound. The second time period may be two hours from the present time or two hours from a predetermined time point.

[0054] If the predicted value X3 calculated in this manner is below the predetermined reference value X and the predicted value Y3 is below the predetermined reference value Y (Yes in step #04 of FIG. 2 ), the control unit 50 switches from the first control to the second control (step #05 of FIG. 2 ). If the predicted value X3 is not below the predetermined reference value X or if the predicted value Y3 is not below the predetermined reference value Y (No in step #04 of FIG. 2 ), the control unit 50 continues to perform the first control (step #06 of FIG. 2 ). As described above, the predetermined reference values ​​X and Y can be set lower than the emission regulation values ​​for hydrogen chloride and sulfur oxide gases in each municipality where the incineration apparatus 1 is installed. Therefore, by setting the predetermined reference values ​​X and Y for each municipality where the incineration apparatus 1 is installed, additives containing sulfur or sulfur compounds can be efficiently added in each incineration apparatus 1, making it possible to prevent corrosion of the waste heat boiler heat transfer tubes 21.

[0055] In the second control, the control unit 50 controls the first adding unit 51 and the second adding unit 52 to add the additive containing sulfur or a sulfur compound and a predetermined amount of acid gas treatment agent (step #07 in FIG. 2). When the addition of the additive containing sulfur or a sulfur compound and the predetermined amount of acid gas treatment agent has been completed (Yes in step #08 in FIG. 2), the control unit 50 switches from the second control to the first control (step #09 in FIG. 2). When the addition of the additive containing sulfur or a sulfur compound and the predetermined amount of acid gas treatment agent has not been completed (No in step #08 in FIG. 2), the control unit 50 continues the second control. The control unit 50 controls the first adding unit 51 and the second adding unit 52 by repeating this cycle.

[0056] If the additive containing sulfur or a sulfur compound added in the first adding unit 51 is sulfuric acid, the temperature of the combustion gas in the secondary combustion chamber 27 is expected to decrease due to the endothermic action of the sulfuric acid. If the temperature of the combustion gas is low, harmful substances such as dioxins contained in the combustion gas will not be sufficiently decomposed. Therefore, to suppress temperature fluctuations in the secondary combustion chamber 27, the control unit 50 may switch from the first control to the second control when the combustion gas temperature near the secondary combustion chamber 27 is equal to or higher than a specified value (e.g., 700°C) and the predicted values ​​X3 and Y3 are lower than the predetermined reference values ​​X and Y. This suppresses the decrease in the temperature of the combustion gas due to the endothermic action of the sulfuric acid and maintains a temperature at which harmful substances such as dioxins can be sufficiently decomposed. In this case, a thermometer for measuring the combustion gas temperature may be provided near the secondary combustion chamber 27.

[0057] [Dust collector, fly ash return conveyor] 3 is a cross-sectional view of the dust collector 40. The dust collector 40 includes a cylindrical container 41 that has a rectangular cross section, extends in the vertical direction, and has a hopper-shaped lower portion. Combustion gas that has flowed through the waste heat boiler 20 flows in through an inlet 42, moves from the bottom to the top of the container 41, and flows out through an outlet 43. Inside the container 41, multiple elongated bag-shaped filter cloths 46 are suspended from the top of the container 41 so as to form a cylindrical shape. The top end of the filter cloths 46 is open, and the inside of the filter cloths 46 communicates with the upper space of the container 41. Above the filter cloths 46, a backwashing device 47 is provided for backwashing the filter cloths 46.

[0058] In the dust collector 40, the combustion gas flowing in through the inlet 42 passes through the filter cloth 46 from the outside to the inside. As a result, solid particles such as fly ash and soot contained in the combustion gas are captured by the filter cloth 46. In this way, the exhaust gas purified by removing the fly ash and the like through the filter cloth 46 flows out from the outlet 43 and flows into the chimney 60.

[0059] When the filter cloth 46 continues to remove fly ash and the like, the fly ash and the like accumulates on the outer surface of the filter cloth 46. Therefore, in the dust collector 40, in order to prevent an increase in pressure loss due to the accumulated fly ash and the like, the filter cloth 46 is backwashed by the backwashing device 47, and the deposits adhering to the outer surface of the filter cloth 46 are brushed off.

[0060] The dust collector 40 further includes a backwashing device control unit 47a that controls the backwashing device 47. The backwashing device control unit 47a is equipped with a processor and operates the backwashing device 47 periodically or at set intervals. During the second control period, a predetermined amount of acid gas treatment agent is added. Unreacted acid gas treatment agent that does not react with hydrogen chloride gas and sulfur oxide gases in the combustion gas is transported to the dust collector 40 by the flow of combustion gas and collected by the filter cloth 46 along with fly ash. The combustion gas passing through the filter cloth 46 contains unreacted hydrogen chloride gas or sulfur oxide gas. The reaction between these gases and the unreacted acid gas treatment agent attached to the surface of the filter cloth 46 reduces the hydrogen chloride and sulfur oxide concentrations in the exhaust gas. Therefore, the backwashing device control unit 47a may change the operation frequency of the backwashing device 47 during the second control period to promote the neutralization reaction in the filter cloth 46.

[0061] The dust collector 40 may be provided with a measuring device that measures the pressure of the exhaust gas discharged from the dust collector 40. The backwashing device control unit 47a may, for example, compare the value measured by the measuring device with the pressure value of the combustion gas flowing into the dust collector 40 and operate the backwashing device 47 when the pressure loss exceeds a certain value. This allows the neutralization reaction in the filter cloth 46 to proceed when the pressure loss is lower than the certain value, thereby reducing the hydrogen chloride concentration and sulfur oxide concentration in the exhaust gas. Note that the backwashing device control unit 47a may operate the backwashing device 47 when switching to the second control to brush off fly ash and the like adhering to the filter cloth 46. This allows the filter cloth 46 to capture unreacted acid gas treatment agent added after the second control, thereby accelerating the neutralization reaction in the filter cloth 46.

[0062] The fly ash and other deposits removed from the filter cloth 46 by the backwashing device 47 are discharged from a discharge port 45 by a fly ash discharger 44 provided at the bottom of the container 41. The fly ash discharger 44 may be of a screw conveyor type. The fly ash and other deposits discharged from the discharge port 45 are returned to the incinerator 10 by a fly ash return conveyor 48 (see FIG. 1).

[0063] The fly ash return conveyor 48 returns fly ash to the incinerator 10 periodically or at set intervals controlled by the conveyor control unit 48a. The conveyor control unit 48a is equipped with a processor, and it is preferable to change the return frequency of the fly ash return conveyor 48 depending on the operation frequency of the backwashing device 47. The conveyor control unit 48a, for example, communicates with the backwashing device control unit 47a to obtain operation information of the backwashing device 47, and then operates the fly ash return conveyor 48 a predetermined time after the backwashing device 47 has started operating. This allows the operation timing of the backwashing device 47 and the fly ash return conveyor 48 to be synchronized, thereby more efficiently returning fly ash and the like to the incinerator 10.

[0064] Other Embodiments (a) In the above embodiment, the first adding unit 51 adds an additive containing sulfur or a sulfur compound to the secondary combustion chamber 27. However, the first adding unit 51 may add the additive in the post-combustion device 28. This makes it possible to suppress a decrease in the temperature of the combustion gas in the vicinity of the secondary combustion chamber 27.

[0065] (b) In the above embodiment, the measuring unit 54 is arranged upstream of the dust collecting device 40, but it may also be arranged downstream of the dust collecting device 40, or the measuring unit 54 may be arranged either upstream or downstream of the dust collecting device 40.

[0066] (c) In the above embodiment, the first adding unit 51 adds an additive containing sulfur or a sulfur compound to the secondary combustion chamber 27, but the additive may also be added in the incinerator 10.

[0067] (d) In the above embodiment, when the predicted values ​​X3, Y3 of the hydrogen chloride concentration and sulfur oxide concentration are lower than the predetermined reference values ​​X, Y, the control unit 50 switches from the first control to the second control. However, the control unit 50 may also switch from the first control to the second control when the measured values ​​X0, Y0 of the hydrogen chloride concentration and sulfur oxide concentration are equal to or lower than the predetermined reference values, or when the average values ​​X1, Y1 are equal to or lower than the predetermined reference values, etc.

[0068] (e) In the above embodiment, the predicted values ​​X3 and Y3 were calculated by adding the expected increases X2 and Y2 in the hydrogen chloride concentration or sulfur oxide concentration due to the addition of the additive containing sulfur or a sulfur compound to the average values ​​X1 and Y1, but a moving average of the hydrogen chloride concentration or sulfur oxide concentration over a predetermined first time period may be used instead of the average values ​​X1 and Y1. Also, the actual values ​​of the increase in the hydrogen chloride concentration or sulfur oxide concentration due to the addition of the additive containing sulfur or a sulfur compound, or the measured values ​​of the combustion gas components at the time of addition, may be stored in the memory unit, and the expected increases X2 and Y2 may be calculated by the calculation unit using these actual values ​​and the measured values.

[0069] (f) In the above embodiment, the backwashing device control unit 47a changes the operation frequency of the backwashing device 47 during the second control, but the backwashing device 47 may be controlled not to operate during the second control. This allows the neutralization reaction in the filter cloth 46 to proceed, thereby reducing the hydrogen chloride concentration and sulfur oxide concentration in the exhaust gas.

[0070] (g) In the above embodiment, the measurement unit 54 measures the hydrogen chloride concentration and the sulfur oxide concentration, but it may measure either the hydrogen chloride concentration or the sulfur oxide concentration. When the measurement unit 54 measures only the hydrogen chloride concentration, the calculation unit may calculate the average value X1 and predicted value X3 of the hydrogen chloride concentration, and the control unit 50 may switch from the first control to the second control when the predicted value X3 of the hydrogen chloride concentration falls below the predetermined reference value X. The same may be true for the sulfur oxide concentration.

[0071] (h) In the above embodiment, the second adding unit 52 adds a predetermined amount of acid gas treatment agent, but the amount of acid gas treatment agent added may be a variable determined based on the measured values ​​X0, Y0 or predicted values ​​X3, Y3 of at least one of the hydrogen chloride concentration and the sulfur oxide concentration. Similarly, the amount of additive added by the first adding unit 51 may be a variable determined based on the measured values ​​X0, Y0 or predicted values ​​X3, Y3 of at least one of the hydrogen chloride concentration and the sulfur oxide concentration. [Industrial Applicability]

[0072] The present invention can be used in an incinerator that can efficiently prevent corrosion of heat transfer tubes in a waste heat boiler. [Explanation of symbols]

[0073] 1: Incinerator 10: Incinerator 20: Waste heat boiler 21: Waste heat boiler heat transfer tube 27: Secondary combustion chamber 40: Dust collector 47: Backwash equipment 47a: Backwash device control section 50: Control unit 51:First addition part 52:Second addition part 54: Measuring part W: Incinerated material X: Predetermined reference value X0: Measurement value X1: Average value X3: Predicted value Y: Predetermined standard value Y0: Measurement value Y1: Average value Y3: Predicted value

Claims

1. an incinerator for incinerating materials containing chlorine compounds; a secondary combustion chamber downstream of the incinerator for generating combustion gases; a waste heat boiler having a waste heat boiler heat transfer tube exposed in a flue; a dust collector that collects ash in the combustion gas downstream of the waste heat boiler; a first adding section that adds an additive containing sulfur or a sulfur compound in the waste heat boiler or upstream of the waste heat boiler; a second adding section that adds an acid gas treatment agent between the waste heat boiler and the dust collector; a control unit that controls the operation of the first addition unit and the second addition unit, The control unit a first control is executed to add the acid gas treatment agent based on a hydrogen chloride concentration and / or a sulfur oxide concentration in the combustion gas downstream of the first addition section; The incineration apparatus is configured to switch to a second control under predetermined conditions, in which the additive containing sulfur or a sulfur compound and a predetermined amount of the acid gas treatment agent are added.

2. a measuring unit that measures at least one of the hydrogen chloride concentration and the sulfur oxide concentration in the combustion gas downstream of the first adding unit, 2. The incineration apparatus according to claim 1, wherein the predetermined condition is a condition in which the measurement value measured by the measurement unit is smaller than a predetermined reference value.

3. a measuring unit that measures at least one of the hydrogen chloride concentration and the sulfur oxide concentration in the combustion gas downstream of the first adding unit; a memory unit that stores the measured values ​​of the hydrogen chloride concentration and / or the sulfur oxide concentration measured by the measurement unit; a calculation unit that calculates a predicted value of a hydrogen chloride concentration and / or a sulfur oxide concentration in the exhaust gas discharged from the dust collector, 2. The incineration apparatus according to claim 1, wherein the predetermined condition is a case where the predicted value calculated by the calculation unit is smaller than a predetermined reference value.

4. The calculation unit an average value of each of said measurements at a predetermined first time; and 4. The incineration apparatus according to claim 3, wherein the predicted value of the hydrogen chloride concentration and / or the sulfur oxide concentration in the exhaust gas discharged from the dust collector after a predetermined second time is calculated based on the average value.

5. The incineration apparatus according to claim 1 , wherein the first adding unit adds the additive containing sulfur or a sulfur compound to the secondary combustion chamber.

6. The incineration apparatus according to claim 1 , wherein the first adding unit adds the additive containing sulfur or a sulfur compound in the incinerator.

7. 2. The incineration apparatus according to claim 1, wherein the control unit, in the second control, starts adding the predetermined amount of the acid gas treatment agent after a predetermined time has elapsed since the start of addition of the additive containing sulfur or a sulfur compound.

8. 8. The incineration apparatus according to claim 1, wherein the additive containing sulfur or a sulfur compound is sulfuric acid.

9. The incineration apparatus according to claim 8, wherein the control unit activates the first addition unit to add the sulfuric acid when the temperature of the combustion gas in the vicinity of the secondary combustion chamber is equal to or higher than a specified value.

10. The incineration apparatus according to claim 1, further comprising a backwashing device that brushes off fly ash adhering to the dust collecting device, and a backwashing device control unit that controls the backwashing device in conjunction with switching between the first control and the second control by the control unit.

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