Waste treatment facility

Abstract

To provide a waste treatment facility capable of preventing excessive heat-up of white smoke preventive air in a white smoke preventive apparatus while effectively utilizing steam generated in a waste heat boiler.SOLUTION: A waste treatment facility 1 comprises: a combustion furnace 10; an exhaust gas passage 50; a smokestack part 16; a waste heat boiler 12 disposed in the exhaust gas passage 50; an exhaust gas heat exchanger 14 disposed on the downstream side of the waste heat boiler 12 and including a heat transfer part for heating white smoke preventive air by transferring a heat of exhaust gas with a temperature decreased by passing through the waste heat boiler 12, to the white smoke preventive air; a white smoke preventive air supply passage 30 for supplying the white smoke preventive air to the exhaust gas heat exchanger 14 and supplying the white smoke preventive air heated by passing through the exhaust gas heat exchanger 14 to the smokestack part 16 or the outside of an outlet of the smokestack part 16; and an air supply part 38 for supplying the white smoke preventive air to the exhaust gas heat exchanger 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a waste treatment facility. [Background technology]

[0002] It is known that a white smoke prevention device is provided in facilities such as incinerators that emit exhaust gas (see Fig. 1 of Patent Document 1). In this facility, a waste heat boiler that uses exhaust gas as a heat source is arranged in the exhaust gas path from the incinerator to the chimney, and the heat of the steam generated in the waste heat boiler is used to heat the white smoke prevention air in the white smoke prevention device.

[0003] Specifically, the white smoke prevention device is disposed in an air supply path provided separately from the exhaust gas path. One end of this air supply path is connected to a blower, and the other end is connected to a chimney. The white smoke prevention device heats the white smoke prevention air by performing heat exchange between a portion of the steam generated in the waste heat boiler and the white smoke prevention air flowing through the air supply path. The heated white smoke prevention air is supplied to the chimney through the air supply path. The remaining steam generated in the waste heat boiler, excluding the steam supplied to the white smoke prevention device, drives an induced draft blower disposed in the exhaust gas path, and is then condensed by a condenser and circulated to the waste heat boiler.

[0004] On the other hand, the exhaust gas flowing through the exhaust gas path is cooled by passing through the waste heat boiler, and then sent to a dust collector such as a ceramic filter to remove dust. Next, sulfur oxides and the like in the exhaust gas are removed in a flue gas treatment tower, and the exhaust gas is supplied to a chimney where it merges with white smoke prevention air supplied from the air supply path and is released to the outside. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5897821 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, in a waste treatment facility such as that shown in Patent Document 1, in order to increase the efficiency of waste heat recovery, it is preferable to supply the heat of the steam generated in the waste heat boiler to other heat utilization equipment such as a steam turbine. Since it is necessary to increase the energy of the steam as much as possible in order to operate heat utilization equipment such as a steam turbine, the temperature of the steam generated in the waste heat boiler is usually quite high.

[0007] If the white smoke prevention air is heated by such high-temperature steam, the white smoke prevention air will be heated to a temperature excessively higher than the lower limit temperature at which the generation of white smoke from the chimney can be prevented. Since the white smoke prevention air is released to the outside after merging with the exhaust gas in the chimney, if the white smoke prevention air is excessively heated, the excess heat will be wasted to the outside, resulting in a problem of reduced waste heat recovery efficiency.

[0008] Furthermore, when the white smoke prevention air is heated by steam generated in the waste heat boiler as described above, the amount of steam used for heating is reduced by the amount of steam available for other heat utilization facilities, resulting in a problem that the scale and number of heat utilization facilities are limited.

[0009] The present invention has been made to solve the above-mentioned problems, and has an object to improve waste heat recovery efficiency in a waste treatment facility equipped with a waste heat boiler placed in an exhaust gas path leading from an incinerator to a chimney, and a white smoke prevention device for preventing the generation of white smoke from the chimney, by preventing excessive heating of the white smoke prevention air in the white smoke prevention device while making effective use of the steam generated in the waste heat boiler. [Means for solving the problem]

[0010] What is provided is a waste treatment facility for treating waste, comprising: an incinerator for incinerating the waste; an exhaust gas path through which exhaust gas discharged from the incinerator flows; a chimney section for discharging the exhaust gas to an external space; a waste heat boiler arranged in the exhaust gas path and using the exhaust gas flowing through the exhaust gas path as a heat source; an exhaust gas heat exchanger arranged downstream of the waste heat boiler in the exhaust gas path and including a heat transfer section for transferring heat of the exhaust gas, the temperature of which has been reduced by passing through the waste heat boiler, to white smoke prevention air to be heated, thereby heating the white smoke prevention air; a white smoke prevention air supply path for supplying the white smoke prevention air to be heated to the exhaust gas heat exchanger and for supplying the white smoke prevention air heated by passing through the exhaust gas heat exchanger to the chimney section; and an air supply section for supplying the white smoke prevention air to be heated to the exhaust gas heat exchanger via the white smoke prevention air supply path.

[0011] According to this waste treatment facility, an exhaust gas heat exchanger is disposed between the waste heat boiler and the chimney in the exhaust gas path, and the white smoke prevention air is heated in the heat exchanger by the heat of the exhaust gas whose temperature has been reduced by passing through the waste heat boiler, thereby preventing the white smoke prevention air from being excessively heated. That is, the high-temperature exhaust gas discharged from the incinerator is cooled by discharging heat by heating the boiler water in the waste heat boiler. In the exhaust gas heat exchanger, the white smoke prevention air is heated by exchanging heat between the cooled exhaust gas (exhaust gas whose temperature has been reduced) and the white smoke prevention air (to be heated) supplied from the air supply unit through the white smoke prevention air supply path. Therefore, compared to the conventional case where the white smoke prevention air is heated only by the high-temperature steam generated in the waste heat boiler, the excessive heating of the white smoke prevention air is suppressed. In addition, since the high-temperature steam generated in the waste heat boiler is not used to heat the white smoke prevention air, the amount of steam available in the heat utilization facility is increased accordingly. Therefore, while effectively utilizing the steam generated in the waste heat boiler, excessive heating of the white smoke prevention air by the white smoke prevention device can be prevented, thereby improving waste heat recovery efficiency.

[0012] The waste treatment facility may further include a heat transfer system temperature detection unit that detects the temperature of the heat transfer section of the exhaust gas heat exchanger itself or a temperature correlating with that temperature as a heat transfer system temperature, and an air supply control unit, and the air supply control unit may execute heat transfer system control that controls the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit so that the heat transfer system temperature detected by the heat transfer system temperature detection unit becomes a predetermined heat transfer system target temperature.

[0013] According to this configuration, the air supply control unit controls the flow rate of white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit so that the heat transfer system temperature, which is the temperature to be detected by the heat transfer system temperature detection unit, becomes a preset heat transfer system target temperature. This makes it possible to suppress an excessive drop in temperature of the heat transfer section of the exhaust gas heat exchanger, and to suppress the occurrence of corrosion of the heat transfer section and corrosion of the exhaust gas path downstream of the heat transfer section (the exhaust gas path from the heat transfer section to the chimney section) caused by the drop in temperature (hereinafter referred to as corrosion of the heat transfer section, etc.). Therefore, it is possible to realize heating of the white smoke prevention air using low-temperature exhaust gas after passing through the waste heat boiler, without causing corrosion of the heat transfer section, etc. of the exhaust gas heat exchanger.

[0014] Here, an example of the temperature of the heat transfer part itself is, for example, the surface temperature of the heat transfer part. Also, an example of a temperature having a correlation with the temperature of the heat transfer part itself is, for example, the temperature of the exhaust gas flowing through the exhaust gas path downstream of the heat transfer part. In this specification, "having a correlation" means a relationship in which a change in one changes the other, and does not necessarily require a two-way causal relationship (a relationship in which a change in one changes the other and a change in the other changes the one).

[0015] The waste treatment equipment further includes a combined exhaust gas system temperature detection unit that detects, as a combined exhaust gas system temperature, the temperature of the combined exhaust gas itself formed by combining the heated white smoke prevention air supplied from the white smoke prevention air supply path in the chimney section and the exhaust gas, or a temperature that is correlated with that temperature, and an air supply control unit, and the air supply control unit may be configured to execute combined exhaust gas system control that controls the flow rate of white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit so that the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection unit becomes a white smoke prevention target temperature that is set to be equal to or higher than a lower limit temperature at which white smoke can be prevented from being generated from the chimney section.

[0016] According to this configuration, the flow rate of white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit is controlled by the air supply control unit so that the combined exhaust gas system temperature, which is the temperature to be detected by the combined exhaust gas system temperature detection unit, becomes the white smoke prevention target temperature. Here, the white smoke prevention target temperature is set to a lower limit temperature or higher that can prevent the generation of white smoke from the chimney unit. Therefore, the generation of white smoke from the chimney unit is suppressed by controlling the combined exhaust gas system temperature to the white smoke prevention target temperature. Note that the lower limit temperature that can prevent the generation of white smoke from the chimney unit is defined as, for example, the minimum temperature (i.e., the saturated steam temperature) required to prevent the water vapor contained in the combined exhaust gas from condensing due to dilution and cooling in the atmosphere when the combined exhaust gas is discharged from the chimney unit. In addition, an example of the temperature of the combined exhaust gas itself is, for example, a temperature detected by a temperature sensor arranged in the combined exhaust gas. In addition, examples of temperatures that have a correlation with the temperature of the combined exhaust gas itself include the wall temperature of the chimney section and the temperature of the white smoke prevention air supplied to the chimney section (the white smoke prevention air that becomes part of the combined exhaust gas after being supplied to the chimney section).

[0017] The waste treatment equipment may further include a heat transfer system temperature detection unit that detects the temperature of the heat transfer section of the exhaust gas heat exchanger itself or a temperature correlating with that temperature as a heat transfer system temperature, and the air supply control unit may be configured to determine whether the heat transfer system temperature detected by the heat transfer system temperature detection unit is a preset heat transfer system target temperature each time before executing the combined exhaust gas system control, and if it is determined that the detected heat transfer system temperature is not the heat transfer system target temperature, to execute heat transfer system control that controls the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit so that the heat transfer system temperature becomes the heat transfer system target temperature, and to execute the combined exhaust gas system control after executing the heat transfer system control.

[0018] According to this, the air supply control unit executes the heat transfer unit system control every time before executing the combined exhaust gas system control, so that the combined exhaust gas system control can be executed while preventing corrosion of the heat transfer unit, etc., to prevent the generation of white smoke. That is, even if the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit increases due to the previous execution of the combined exhaust gas system control, causing the temperature of the heat transfer unit of the exhaust gas heat exchanger to fall below the heat transfer unit system target temperature, the heat transfer unit system control is executed without fail before the next execution of the combined exhaust gas system control, and the amount of white smoke prevention air supplied by the air supply unit is controlled so that the temperature of the heat transfer unit becomes the heat transfer unit system target temperature. Therefore, the combined exhaust gas system control can be executed while preventing an excessive temperature drop in the heat transfer unit of the exhaust gas heat exchanger and preventing corrosion of the heat transfer unit, etc.

[0019] The waste treatment equipment may further include a heat transfer system temperature detection unit that detects the temperature of the heat transfer section of the exhaust gas heat exchanger itself or a temperature that has a correlation with that temperature as a heat transfer system temperature, and the air supply control unit is configured to execute heat transfer system control in parallel with the combined exhaust gas system control, which controls the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit so that the heat transfer system temperature detected by the heat transfer system temperature detection unit becomes a predetermined heat transfer system target temperature, and may be further configured to be capable of executing a priority control process that causes the heat transfer system control to be executed in priority to the combined exhaust gas system control in order to avoid a situation in which the operation of the air supply unit based on the combined exhaust gas system control interferes with the operation of the air supply unit based on the heat transfer system control.

[0020] According to this configuration, the air supply control unit executes the heat transfer system control and the combined exhaust gas system control in parallel, so that even if the combined exhaust gas system control is being performed (in other words, even if the combined exhaust gas system temperature has not reached the white smoke prevention target temperature), if the heat transfer system temperature falls below the heat transfer system target temperature, the heat transfer system temperature can be quickly returned to the heat transfer system target temperature based on the heat transfer system control. Therefore, corrosion of the heat transfer unit and the like caused by an excessive temperature drop in the heat transfer unit can be more reliably suppressed. Furthermore, the heat transfer system control is executed with priority over the combined exhaust gas system control by the priority control process, so that interference between the operation of the air supply unit based on the combined exhaust gas system control and the operation of the air supply unit based on the heat transfer system control can be prevented.

[0021] The waste treatment facility may include a heat recovery exchanger that is disposed in the white smoke prevention air supply path and recovers heat from the heated white smoke prevention air flowing through the white smoke prevention air supply path and uses the recovered heat to heat a fluid to be heated, which is any one of supply boiler water to be supplied to the waste heat boiler, combustion air to be supplied to the incinerator, and a fluid for heating waste to be input to the incinerator, and a heat exchange amount variable mechanism that can change at least one of the flow rate of the white smoke prevention air, which is the subject of heat recovery flowing into the heat recovery heat exchanger, and the flow rate of the fluid to be heated.

[0022] According to this waste treatment facility, when the temperature of the white smoke prevention air after heating that has passed through the exhaust gas heat exchanger (an example of the temperature of the combined exhaust gas system) is higher than a preset white smoke prevention target temperature, for example, the excess heat held by the white smoke prevention air can be recovered by the recovery heat exchanger to lower the temperature of the white smoke prevention air. Therefore, it is possible to prevent the temperature of the white smoke prevention air supplied to the chimney from becoming higher than necessary and the held heat being wasted to the outside. In addition, the amount of heat recovered from the white smoke prevention air in the recovery heat exchanger can be adjusted by changing at least one of the inflow flow rate of the white smoke prevention air that is the object of heat recovery flowing into the recovery heat exchanger and the inflow flow rate of the fluid to be heated (either the supply boiler water, the combustion air, or the fluid for heating the waste) that flows into the recovery heat exchanger, using a heat exchange amount variable mechanism. Therefore, the temperature of the white smoke prevention air after passing through the exhaust gas heat exchanger can be appropriately controlled by adjusting the amount of heat recovered from the white smoke prevention air in the recovery heat exchanger by the heat exchange amount variable mechanism according to the temperature of the white smoke prevention air after passing through the exhaust gas heat exchanger.

[0023] The waste treatment facility further comprises a combined exhaust gas system temperature detection unit that detects, as a combined exhaust gas system temperature, a temperature that correlates with the temperature of the combined exhaust gas formed by combining the heated white smoke prevention air supplied from the white smoke prevention air supply path and the exhaust gas in the chimney section, and a heat exchange control unit, and it is preferable that the heat exchange control unit executes combined exhaust gas system control that controls, by the heat exchange amount variable mechanism, at least one of the flow rate of the white smoke prevention air, which is the object of heat recovery flowing into the heat recovery exchanger, and the flow rate of the fluid to be heated, so that the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection unit becomes a white smoke prevention target temperature that is set to be equal to or higher than a lower limit temperature at which white smoke can be prevented from being generated from the chimney section.

[0024] According to this configuration, at least one of the flow rate of the white smoke prevention air, which is the heat recovery target flowing into the heat recovery exchanger, and the flow rate of the fluid to be heated, is controlled by the heat exchange amount variable mechanism so that the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection unit becomes the white smoke prevention target temperature set to be equal to or higher than the lower limit temperature at which generation of white smoke from the chimney can be prevented under control of the heat exchange control unit. Therefore, when the temperature of the white smoke prevention air after passing through the exhaust gas heat exchanger (an example of the combined exhaust gas system temperature) is higher than the preset white smoke prevention target temperature, the operation of the heat exchange amount variable mechanism is controlled by the heat exchange control unit to recover excess heat held by the white smoke prevention air to the fluid to be heated in the heat recovery exchanger, thereby preventing the temperature of the white smoke prevention air supplied to the chimney from becoming excessively high, and preventing a decrease in waste heat recovery efficiency.

[0025] The waste treatment facility may include a bypass path branching off from the white smoke prevention air supply path and bypassing the exhaust gas heat exchanger to supply white smoke prevention air to the chimney portion, a steam heat exchanger provided in the bypass path and heating the white smoke prevention air by transferring heat of a portion of the steam generated in the waste heat boiler to the white smoke prevention air flowing through the bypass path, and a steam-side air amount variable mechanism capable of changing the flow rate of the white smoke prevention air flowing from the white smoke prevention air supply path through the bypass path to the steam heat exchanger.

[0026] According to this waste treatment facility, when the temperature of the white smoke prevention air after passing through the exhaust gas heat exchanger (an example of the combined exhaust gas system temperature) is lower than a preset white smoke prevention target temperature, a portion of the white smoke prevention air (the white smoke prevention air flowing into the bypass path) is heated by the steam heat exchanger, which has a higher air heating capacity than the exhaust gas heat exchanger, so that the temperature of the white smoke prevention air (the white smoke prevention air formed by the joining of the white smoke prevention air heated by the exhaust gas heat exchanger and the white smoke prevention air heated by the steam heat exchanger) finally supplied to the chimney can be raised to a temperature at which the generation of white smoke can be prevented.

[0027] The waste treatment facility may further include a combined exhaust gas system temperature detection unit that detects, as a combined exhaust gas system temperature, a temperature that correlates with the temperature of the combined exhaust gas formed by combining the heated white smoke prevention air supplied from the white smoke prevention air supply path and the bypass path and the exhaust gas in the chimney section, and a steam-side air amount control unit, and the steam-side air amount control unit may be configured to execute combined exhaust gas system control that controls the flow rate of white smoke prevention air flowing from the white smoke prevention air supply path through the bypass path to the steam heat exchanger, using the steam-side air amount variable mechanism, so that the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection unit becomes a white smoke prevention target temperature that is set to be equal to or higher than a lower limit temperature at which white smoke can be prevented from being generated from the chimney section.

[0028] According to this configuration, the flow rate of white smoke prevention air flowing from the white smoke prevention air supply path through the bypass path to the steam heat exchanger is controlled by the steam-side air amount variable mechanism so that the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection part becomes a white smoke prevention target temperature set to be equal to or higher than a lower limit temperature at which generation of white smoke from the chimney part can be prevented under control of the steam-side air amount control part. Therefore, when the temperature of the white smoke prevention air after passing through the exhaust gas heat exchanger is lower than a temperature necessary for preventing generation of white smoke, the steam-side air amount variable mechanism supplies a part of the white smoke prevention air to the steam heat exchanger, which has a higher air heating power than the exhaust gas heat exchanger, so that the temperature of the white smoke prevention air finally supplied to the chimney part (the white smoke prevention air obtained by joining the white smoke prevention air heated by the exhaust gas heat exchanger and the white smoke prevention air heated by the steam heat exchanger) can be raised to a temperature necessary for preventing white smoke. In this way, by heating only a portion of the white smoke prevention air supplied to the chimney section by the steam heat exchanger, and heating the remaining white smoke prevention air by the exhaust gas heat exchanger that uses low-temperature exhaust gas, excessive heating of the white smoke prevention air can be prevented and waste heat recovery efficiency can be improved compared to the conventional case in which all of the white smoke prevention air is overheated with high-temperature steam.

[0029] In the waste treatment facility, the steam generated in the waste heat boiler is preferably supplied to another heat utilization facility for an application other than that for heating the white smoke prevention gas.

[0030] According to this configuration, it is possible to effectively utilize the steam generated in the waste heat boiler, and to prevent the white smoke prevention air from being excessively heated by the high-temperature steam generated by the waste heat boiler. Effect of the Invention

[0031] As described above, according to the present invention, steam generated in a waste heat boiler can be effectively utilized, and excessive heating of white smoke prevention air by the white smoke prevention device can be prevented, thereby improving waste heat recovery efficiency. [Brief description of the drawings]

[0032] [Figure 1] 1 is a flow sheet of a waste treatment facility according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a configuration of a control system including a controller of the waste treatment facility in the first embodiment. [Diagram 3] 5 is a flowchart showing an overall flow of white smoke prevention control executed by a controller in the first embodiment. [Figure 4] 5 is a flowchart showing the content of heat transfer system control which is a part of white smoke prevention control in the first embodiment. [Diagram 5] 5 is a flowchart showing the content of a combined exhaust gas system control which is a part of the white smoke prevention control in the first embodiment. [Figure 6A] 5 is a flowchart showing an overall flow of white smoke prevention control executed by a controller in a modified example of the first embodiment. [Figure 6B] 10 is a flowchart showing the contents of a priority control process executed by a controller in a modified example of the first embodiment. [Figure 7] FIG. 2 is a view corresponding to FIG. 1 and showing a second embodiment of the present invention. [Figure 8] FIG. 3 is a view corresponding to FIG. 2 and showing the second embodiment. [Figure 9] FIG. 6 is a view corresponding to FIG. 5 and showing the second embodiment. [Figure 10] FIG. 8 (FIG. 1) is a view showing a first modified example of the second embodiment. [Figure 11] FIG. 11 is a view corresponding to FIG. 1 in a third embodiment of the present invention. [Figure 12] FIG. 11 is a view equivalent to FIG. 2 in the third embodiment. [Figure 13] FIG. 7 is a view equivalent to FIG. 5 in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] (First embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0034] As shown in FIG. 1, the waste treatment equipment 1A according to this embodiment includes an incinerator 10, a combustion air preheater 11, a waste heat boiler 12, a dust collector 13, an exhaust gas heat exchanger 14, a flue gas treatment tower 15, a chimney section 16, a drying device 17, a steam power generation device 18, a combustion air blower 19, a combustion air supply path 40, and an exhaust gas path 50.

[0035] The combustion air preheater 11, the waste heat boiler 12, the dust collector 13, the exhaust gas heat exchanger 14, the flue gas treatment tower 15 and the chimney section 16 are arranged in this order from the upstream side on the exhaust gas path 50.

[0036] The exhaust gas path 50 is arranged so as to allow the exhaust gas discharged from the incinerator 10 to flow through the exhaust gas path 50 and be discharged from the chimney portion 16. Specifically, the exhaust gas path 50 includes a first path portion 51, a second path portion 52, a third path portion 53, a fourth path portion 54, a fifth path portion 55, and a sixth path portion 56. The first path portion 51 connects the outlet of the incinerator 10 and the inlet of the combustion air preheater 11. The second path portion 52 connects the outlet of the combustion air preheater 11 and the inlet of the waste heat boiler 12. The third path portion 53 connects the outlet of the waste heat boiler 12 and the inlet of the dust collector 13. The fourth path portion 54 connects the outlet of the dust collector 13 and the inlet of the exhaust gas heat exchanger 14. The fifth path section 55 connects the outlet of the exhaust gas heat exchanger 14 and the inlet of the flue gas treatment tower 15. The sixth path section 56 connects the outlet of the flue gas treatment tower 15 and the inlet of the chimney section 16. An induction blower 21 that induces exhaust gas from the flue gas treatment tower 15 toward the chimney section 16 is disposed in the sixth path section 56. The temperature of the exhaust gas flowing through the first path section 51 is, for example, about 800°C to 850°C, the temperature of the exhaust gas flowing through the second path section 52 is, for example, about 600°C to 650°C, the temperature of the exhaust gas flowing through the third path section 53 and the fourth path section 54 is, for example, about 200°C to 300°C, the temperature of the exhaust gas flowing through the fifth path section 55 is, for example, about 100°C, and the temperature of the exhaust gas flowing through the sixth path section 56 is, for example, about 50°C.

[0037] The incinerator 10 incinerates waste materials such as dewatered sludge, dried sludge obtained by drying the dewatered sludge, etc. The incinerator 10 in this embodiment is a fluidized bed incinerator, but is not limited to this.

[0038] The combustion air preheater 11 heats the combustion air by the heat of the exhaust gas discharged from the incinerator 10. Specifically, the combustion air preheater 11 exchanges heat between the exhaust gas flowing into the combustion air preheater 11 through the first path section 51 and the combustion air supplied from the combustion air blower 19 through the combustion air supply path 40. The combustion air blower 19 supplies the combustion air heated by the combustion air preheater 11 to the lower part of the incinerator 10. Meanwhile, the exhaust gas flowing into the combustion air preheater 11 through the first path section 51 is cooled by heat exchange with the combustion air, and then flows into the waste heat boiler 12 through the second path section 52.

[0039] The waste heat boiler 12 heats the boiler water in the waste heat boiler 12 by exchanging heat between the exhaust gas flowing into the waste heat boiler 12 through the second path portion 52 and the boiler water in the waste heat boiler 12, thereby generating steam. A water supply path 22 for supplying the boiler water is connected to the waste heat boiler 12. A water supply pump 23 is connected to the upstream end of the water supply path 22, and the water supply pump 23 draws in supply boiler water (water used as boiler water in the waste heat boiler 12) stored in a water supply tank 24 and supplies it to the waste heat boiler 12.

[0040] The steam generated in the waste heat boiler 12 is supplied to the drying device 17 and the steam power generation device 18 (both are examples of heat utilization equipment) via steam supply paths 25a and 25b, respectively. The supply flow rate of the steam to each of the steam supply paths 25a and 25b is controlled by a damper (not shown) driven by a controller 100A described later. The control of the supply flow rate of the steam to the heat utilization equipment is not limited to the control by the damper. For example, the supply flow rate of the steam to the steam supply path 25a for supplying the steam to the drying device 17 may be controlled by providing a steam trap downstream of the heat exchanger in the drying device 17, so that a part of the steam recovered from the heat exchanger is condensed and discharged as drain, and the steam discharged is replenished as it goes along. The drying device 17 is provided upstream of the waste supply port 10a of the incinerator 10, and is a device that evaporates the moisture of the waste input from the waste supply port 10a into the incinerator 10. The white arrow in FIG. 1 indicates the input path of this waste. The condensed water after the steam is used in the drying device 17 is returned (circulated) to the water supply tank 24 via the return path 41. This return (circulation) of the condensed water via the return path 41 is not necessarily required. The steam power generation device 18 has a steam turbine that is driven by the energy of steam, and generates electricity by transmitting the rotational motion of the steam turbine to a generator. The steam power generation device 18 is, for example, a binary power generation device that boils a working medium with a boiling point lower than that of water by using the energy of steam, and rotates a steam turbine with the steam of the working medium.

[0041] The exhaust gas that flows into the waste heat boiler 12 through the second path section 52 is cooled (reduced in temperature) by heating the boiler water in the waste heat boiler 12, and the cooled exhaust gas flows into the dust collector 13 through the third path section 53.

[0042] The dust collector 13 is configured with a bag filter that collects soot and the like contained in the exhaust gas that flows into the dust collector 13 through the third path portion 53. The dust collector 13 is not limited to a bag filter, and may be configured with, for example, a ceramic filter or the like. In addition, when the temperature of the exhaust gas flowing into the dust collector 13 is higher than the heat resistance temperature of the dust collector 13, a cooling device (not shown) may be separately provided. The exhaust gas that has passed through the dust collector 13 flows into the exhaust gas heat exchanger 14 through the fourth path portion 54.

[0043] The exhaust gas heat exchanger 14 heats the white smoke prevention air by performing heat exchange between the exhaust gas flowing into the exhaust gas heat exchanger 14 through the fourth path section 54 and the white smoke prevention air (air to be heated) supplied to the exhaust gas heat exchanger 14 through the white smoke prevention air supply path 30 as described below. The white smoke prevention air heated in the exhaust gas heat exchanger 14 is supplied to the chimney section 16 (inside the chimney section 16 in this example) to prevent the generation of white smoke from the chimney section 16. On the other hand, the exhaust gas that has heated the white smoke prevention air in the exhaust gas heat exchanger 14 is cooled by the heating (by providing heat to the white smoke prevention air) and is supplied to the lower end of the flue gas treatment tower 15 through the fifth path section 55.

[0044] The flue gas treatment tower 15 purifies the exhaust gas flowing into the flue gas treatment tower 15 through the fifth path section 55. In this first embodiment, the flue gas treatment tower 15 adopts a wet type as an exhaust gas purification method. That is, the flue gas treatment tower 15 removes fine particles and harmful substances (hydrogen chloride, sulfur oxides, etc.) in the exhaust gas by injecting water or chemicals (e.g., alkaline chemicals such as caustic soda) into the exhaust gas passing through the tower using a spray device provided inside the flue gas treatment tower 15. The exhaust gas rises from the lower end to the upper end of the flue gas treatment tower 15, and is then guided to the chimney section 16 through the sixth path section 56. Note that the method of purifying the exhaust gas in the flue gas treatment tower 15 is not limited to a wet type, and may be, for example, a dry type or another purification method.

[0045] The chimney portion 16 is located at the downstream end of the exhaust gas passage 50. In this first embodiment, the chimney portion 16 is fixed to the upper end of the flue gas treatment tower 15. The chimney portion 16 allows the exhaust gas that flows into the chimney portion 16 through the sixth passage portion 56 to be discharged to the outside space (atmosphere) through the chimney portion 16. Here, the downstream end of the white smoke prevention air supply passage 30 described later is connected to the chimney portion 16, and the exhaust gas that flows into the chimney portion 16 is discharged to the outside from the chimney portion 16 after merging with the white smoke prevention air that flows in through the white smoke prevention air supply passage 30. This white smoke prevention air is heated by the exhaust gas heat exchanger 14, and in this first embodiment, the heat of the white smoke prevention air is used to increase the temperature of the combined exhaust gas to prevent the generation of white smoke.

[0046] The chimney portion 16 may have any configuration as long as its end portion has an opening communicating with the outside space, and may be simply a duct that constitutes the exhaust gas path 50.

[0047] Referring to FIG. 1, the waste treatment facility 1A further includes the air supply path 30 and an air supply unit .

[0048] The white smoke prevention air supply path 30 is an air supply path for supplying white smoke prevention air to the chimney portion 16, and is provided separately and independently from the exhaust gas path 50 and the combustion air supply path 40.

[0049] The white smoke prevention air supply path 30 is an air supply path for supplying white smoke prevention air to the exhaust gas heat exchanger 14, and for supplying the white smoke prevention air after passing through the exhaust gas heat exchanger 14 (after being heated) to the chimney section 16. Specifically, the white smoke prevention air supply path 30 has a white smoke prevention upstream path section 30a located upstream of the exhaust gas heat exchanger 14, and a white smoke prevention downstream path section 30b located downstream of the exhaust gas heat exchanger 14.

[0050] The white smoke prevention blower 20 is disposed at the upstream end of the white smoke prevention upstream path section 30a, and an upstream damper 31 is provided upstream of the white smoke prevention blower 20 in the white smoke prevention upstream path section 30a, and a downstream damper 32 is disposed downstream. The white smoke prevention upstream path section 30a has an upstream end connected to the upstream damper 31 and a downstream end connected to the air inlet of the exhaust gas heat exchanger 14. The white smoke prevention downstream path section 30b has an upstream end connected to the air outlet of the exhaust gas heat exchanger 14 and a downstream end connected to the chimney section 16. The white smoke prevention air that has passed through the exhaust gas heat exchanger 14 is supplied to the chimney section 16 via the white smoke prevention downstream path section 30b, and merges with the exhaust gas in the chimney section 16. In the following description, the mixture of the white smoke prevention air and the exhaust gas in the chimney section 16 is referred to as the merged exhaust gas.

[0051] The air supply unit 38 is capable of changing the flow rate of the white smoke prevention air that flows through the white smoke prevention air supply path 30 and is supplied to the exhaust gas heat exchanger 14. The air supply unit 38 in this embodiment includes the white smoke prevention blower 20 that sends out white smoke prevention air, the upstream damper 31 that is arranged upstream of the white smoke prevention blower 20 and capable of adjusting the amount of air on the suction side of the white smoke prevention blower 20, and the downstream damper 32 that is arranged downstream of the white smoke prevention blower 20 and capable of adjusting the amount of air discharged from the white smoke prevention blower 20. Each of the "dampers" described in this specification is an opening / closing member having an opening degree that can be changed according to a command signal input to the damper, and is configured to allow a fluid to flow through the damper at a flow rate corresponding to the opening degree.

[0052] Referring to FIG. 1, the waste treatment facility 1A further includes a combined exhaust gas system temperature detector 70 and a heat transfer system temperature detector 71.

[0053] The combined exhaust gas system temperature detection unit 70 detects a temperature that has a correlation with the temperature of the combined exhaust gas (gas in which the white smoke prevention air and the exhaust gas have merged) flowing through the chimney 16 as the combined exhaust gas system temperature. Here, "having a correlation" means a relationship in which one is related to the other such that a change in one changes the other, and does not necessarily require a bilateral causal relationship (a relationship in which a change in one changes the other and a change in the other changes the other). In this embodiment, as an example of the combined exhaust gas system temperature, the temperature of the white smoke prevention air (white smoke prevention air flowing through the white smoke prevention downstream path 30b) flowing downstream of the exhaust gas heat exchanger 14 is detected. The temperature of the white smoke prevention air flowing through the white smoke prevention downstream path 30b corresponds to a temperature that has a correlation with the temperature of the combined exhaust gas because a change in the temperature (one side) of the white smoke prevention air also changes the temperature of the combined exhaust gas (the other side) flowing through the chimney 16. Here, in the white smoke prevention air downstream path section 30b, the further downstream the white smoke prevention air flows, the stronger its effect on the temperature of the combined exhaust gas (i.e., the correlation). Therefore, in this embodiment, in order to further strengthen the correlation with the temperature of the combined exhaust gas, the combined exhaust gas system temperature detection section 70 is configured to detect the temperature of the downstream end of the white smoke prevention air downstream path section 30b (i.e., the portion adjacent to the upstream side of the supply port of the white smoke prevention air in the chimney section 16). The combined exhaust gas system temperature detection section 70 then transmits information on the detected combined gas system temperature to the controller 100A, which will be described later.

[0054] In this embodiment, the temperature of the white smoke prevention air is used as the temperature having a correlation with the temperature of the combined exhaust gas, but the present invention is not limited to this, and for example, the temperature of the wall surface of the chimney section 16 may be used. In this case, when the temperature (one side) of the combined exhaust gas flowing through the chimney section 16 changes, the temperature of the wall surface (the other side) of the chimney section 16 also changes, so it can be said that there is a correlation between the temperature of the wall surface of the chimney section 16 and the temperature of the combined exhaust gas.

[0055] In this embodiment, the combined exhaust gas system temperature is a temperature that has a correlation with the temperature of the combined exhaust gas flowing through the chimney section 16, but is not limited to this and may be the temperature of the combined exhaust gas itself. In this case, the combined exhaust gas system temperature detection section 70 directly detects the temperature of the combined exhaust gas flowing through the chimney section 16 and transmits information on the detected temperature to a controller 100A (see FIG. 2) described later.

[0056] The heat transfer system temperature detection unit 71 is provided in the exhaust gas heat exchanger 14 and detects the temperature of the heat transfer section of the exhaust gas heat exchanger 14 itself (in this example, the surface temperature of the heat transfer section) as the heat transfer system temperature, and transmits the detected temperature information to the controller 100A described later.

[0057] In this embodiment, the heat transfer section temperature is the temperature of the heat transfer section of the exhaust gas heat exchanger 14 itself, but is not limited thereto and may be a temperature having a correlation with the temperature. The correlation is defined as a relationship in which one changes when the other changes, as explained in the definition of the combined exhaust gas system temperature above, and does not necessarily require a bilateral causal relationship. An example of a temperature having a correlation with the temperature of the heat transfer section is, for example, the temperature of the exhaust gas at the exhaust gas outlet side (exhaust gas downstream side) of the exhaust gas heat exchanger 14, in other words, the temperature of the exhaust gas flowing through the fifth path section 55.

[0058] The waste treatment facility 1A further includes a controller 100A (see FIG. 2) for controlling the operation of the air supply unit 38 (in this embodiment, the white smoke prevention blower 20, the upstream damper 31, and the downstream damper 32).

[0059] The controller 100A executes white smoke prevention control for preventing the generation of white smoke from the chimney 16, based on the respective temperatures to be detected by the combined exhaust gas system temperature detection section 70 and the heat transfer system temperature detection section 71.

[0060] White smoke prevention control is broadly divided into heat transfer system control and combined exhaust gas system control (see Figure 3, described later).

[0061] In the heat transfer system control, the flow rate of white smoke prevention air supplied by the air supply unit 38 is controlled so that the temperature detected by the heat transfer system temperature detection unit 71 (heat transfer system temperature) becomes the heat transfer system target temperature, which is the target temperature.

[0062] In the combined exhaust gas system control, the flow rate of white smoke prevention air supplied by the air supply unit 38 is controlled so that the temperature detected by the combined exhaust gas system temperature detection unit 70 (combined exhaust gas system temperature) becomes the white smoke prevention target temperature, which is the target temperature.

[0063] 2, the controller 100A includes a CPU (Central Processing Unit) (not shown), a reception unit 101, and a storage unit 110, and the CPU realizes a predetermined function by executing a program stored in the storage unit 110. The predetermined function includes a determination unit 102 and a flow rate adjustment unit 103. The storage unit 110 is configured by a storage device such as a memory.

[0064] The receiving unit 101 receives input of temperature information transmitted from the combined exhaust gas system temperature detecting unit 70 and the heat transfer system temperature detecting unit 71 to the controller 100A.

[0065] The storage unit 110 stores the heat transfer system target temperature and the white smoke prevention target temperature in advance. In this embodiment, the heat transfer system target temperature is set to a lower limit temperature or higher that can prevent corrosion of the heat transfer section of the exhaust gas heat exchanger 14 caused by an excessive temperature drop of the heat transfer section. The heat transfer system target temperature may be set to a lower limit temperature or higher that can prevent corrosion of the piping downstream of the heat transfer section of the exhaust gas heat exchanger 14. The heat transfer system target temperature is not limited to a specific temperature, and may be a temperature range having a finite width above and below, or may be a temperature range having only a lower threshold temperature. In this embodiment, the heat transfer system target temperature is set to a temperature range having a width above and below (for example, a temperature range of 70°C to 110°C).

[0066] The white smoke prevention target temperature is set to a lower limit temperature or higher that can prevent the generation of white smoke from the chimney portion 16 (condensation of water vapor in the combined exhaust gas formed by the joining of the white smoke prevention air and the exhaust gas). The white smoke prevention target temperature is not limited to one specific temperature, but may be a temperature range having a finite width above and below, or may be a temperature range having only a lower limit threshold temperature. In this embodiment, the white smoke prevention target temperature is set to a temperature range having a width above and below (for example, a temperature range of 70°C to 90°C).

[0067] The determination unit 102 determines whether the heat transfer system temperature detected by the heat transfer system temperature detection unit 71 is greater than, less than, or equal to the heat transfer system target temperature stored in the storage unit 110, and outputs the determination result to the flow rate adjustment unit 103. Note that "equal" here does not necessarily mean that the detected heat transfer system temperature and the heat transfer system target temperature are exactly the same value, but may have some margin of error above and below.

[0068] Furthermore, the determination unit 102 determines whether the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection unit 70 is greater than, smaller than, or equal to the white smoke prevention target temperature stored in the memory unit 110, and outputs the determination result to the flow rate adjustment unit 103. Note that "equal" here does not necessarily mean that the detected combined exhaust gas system temperature and the white smoke prevention target temperature are exactly the same value, but may also have some error range above and below.

[0069] When the heat transfer system control is executed, the flow rate adjustment unit 103 controls the operation of the air supply unit 38 based on the output result of the judgment unit 102 so that the temperature detected by the heat transfer system temperature detection unit 71 becomes the above-mentioned heat transfer system target temperature, and when the combined exhaust gas system control is executed, the flow rate adjustment unit 103 controls the operation of the air supply unit 38 so that the temperature detected by the combined exhaust gas system temperature detection unit 70 becomes the above-mentioned white smoke prevention target temperature.

[0070] Hereinafter, the white smoke prevention control executed by the controller 100A will be described in detail with reference to FIGS.

[0071] 3 shows the overall flow of the white smoke prevention control. In this white smoke prevention control, the controller 100A first executes the heat transfer section system control (step SA1), and after the heat transfer section system control is completed, executes the combined exhaust gas system control (step SA2), repeating the process.

[0072] Fig. 4 is a flow chart showing details of the heat transfer section control. In this heat transfer section control, during continuous operation of the incinerator 10, the temperature of the heat transfer section of the exhaust gas heat exchanger 14 is detected by the heat transfer section temperature detection unit 71, and the detected temperature information is received by the reception unit 101 (step SA101). Then, the detection data including the temperature information of the heat transfer section is input to the judgment unit 102 (see Fig. 2) through the reception unit 101.

[0073] The determination unit 102 determines whether or not the temperature related to the detection data, that is, the temperature of the heat transfer section (an example of the heat transfer system temperature) detected by the heat transfer system temperature detection unit 71, is the heat transfer system target temperature (step SA102).

[0074] When the determination unit 102 determines that the detected temperature of the heat transfer section is not the heat transfer section target temperature (NO in step SA102), the determination unit 102 further determines whether the detected temperature of the heat transfer section is lower than the heat transfer section target temperature (step SA103). When the determination unit 102 determines that the detected temperature of the heat transfer section is lower than the heat transfer section target temperature (YES in step SA103), the flow rate adjustment unit 103 reduces the opening degree of the upstream damper 31 or the downstream damper 32 (see FIG. 1) arranged on both sides of the white smoke prevention blower 20, or reduces the rotation speed of the white smoke prevention blower 20 (step SA104). As a result, the flow rate of the white smoke prevention air supplied to the heat transfer section of the exhaust gas heat exchanger 14 is reduced to reduce the amount of heat recovered from the heat transfer section to the white smoke prevention air, thereby increasing the temperature of the heat transfer section. After executing step SA104, the process returns to step SA101. If the determination unit 102 determines that the detected temperature of the heat transfer section is higher than the heat transfer section target temperature (NO in step SA103), the flow rate adjustment unit 103 increases the opening of the upstream damper 31 or downstream damper 32, or increases the rotation speed of the white smoke prevention blower 20 (step SA105). This increases the flow rate of the white smoke prevention air supplied to the heat transfer section of the exhaust gas heat exchanger 14, thereby increasing the amount of heat dissipated from the heat transfer section to the white smoke prevention air, thereby lowering the temperature of the heat transfer section. Then, after executing step SA105, the process returns to step SA101.

[0075] On the other hand, in step SA102, if the judgment unit 102 judges that the detected temperature of the heat transfer section is the heat transfer section target temperature (YES in step SA102), the flow rate adjustment unit 103 maintains the opening degrees of the upstream damper 31 and the downstream damper 32 and the rotation speed of the white smoke prevention blower 20 as they are, terminates the heat transfer section system control (processing of steps SA101 to SA105), and proceeds to step SA201 (see Figures 3 and 5) for executing the combined exhaust gas system control.

[0076] Fig. 5 is a flow chart showing details of the combined exhaust gas system control. In this combined exhaust gas system control, the temperature of the white smoke prevention air flowing through the white smoke prevention downstream path portion 30b, which is the downstream portion of the exhaust gas heat exchanger 14 in the white smoke prevention air supply path 30 (see Fig. 1) (an example of the combined exhaust gas system temperature), i.e., the temperature of the white smoke prevention air heated by passing through the exhaust gas heat exchanger 14, is detected by the combined exhaust gas system temperature detection unit 70, and the detected temperature information is received by the reception unit 101 (step SA201). Then, detection data including information on the temperature of the white smoke prevention air is input to the determination unit 102 through the reception unit 101.

[0077] The determination unit 102 determines whether or not the temperature related to the detection data, i.e., the temperature of the white smoke prevention air detected by the junction exhaust gas system temperature detection unit 70, is the white smoke prevention target temperature (step SA202). When the determination unit 102 determines that the detected temperature of the white smoke prevention air is not the white smoke prevention target temperature (NO in step SA202), the determination unit 102 further determines whether or not the detected temperature of the white smoke prevention air is lower than the white smoke prevention target temperature (step SA203). When the determination unit 102 determines that the detected temperature of the white smoke prevention air is lower than the white smoke prevention target temperature (YES in step SA203), the flow rate adjustment unit 103 increases the opening degree of the upstream damper 31 or downstream damper 32 arranged on both sides of the white smoke prevention blower 20, or increases the rotation speed of the white smoke prevention blower 20 (step SA204). As a result, the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger 14 is increased, and the amount of heat recovered from the exhaust gas to the white smoke prevention air in the exhaust gas heat exchanger 14 is increased, thereby compensating for the insufficient heat recovery by the white smoke prevention air. On the other hand, if the detected temperature of the white smoke prevention air is higher than the white smoke prevention target temperature (NO in step SA203), the flow rate adjustment unit 103 reduces the opening degree of the upstream damper 31 or the downstream damper 32, or reduces the rotation speed of the white smoke prevention blower 20 (step SA205). As a result, the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger 14 is reduced, and the amount of heat recovered from the exhaust gas to the white smoke prevention air in the exhaust gas heat exchanger 14 is reduced, thereby suppressing excessive heat recovery to the white smoke prevention air. At the same time, the power consumption of the white smoke prevention blower 20 is also reduced. Then, after the processing of step SA204 or step SA205 is completed, the process returns to step SA201. The above operation is repeated until the detected temperature of the white smoke prevention air reaches the white smoke prevention target temperature (until step SA202 returns YES). If the determination unit 102 determines in step SA202 that the detected temperature of the white smoke prevention air reaches the white smoke prevention target temperature (step SA202 returns YES), the combined exhaust gas system control (the processing of steps SA201 to SA205) is terminated, and the process returns to step SA101 (see FIGS. 3 and 4) to execute heat transfer system control.

[0078] [Effects] As described above, according to the waste treatment facility 1A of this embodiment, the exhaust gas heat exchanger 14 is disposed between the waste heat boiler 12 and the chimney 16 in the exhaust gas passage 50, and the white smoke prevention air is heated by the heat of the relatively low-temperature exhaust gas after passing through the waste heat boiler 12 in the exhaust gas heat exchanger 14, so that the white smoke prevention air can be prevented from being excessively heated. Therefore, compared to the conventional case where the white smoke prevention air is heated by the high-temperature steam generated in the waste heat boiler 12, the white smoke prevention air is prevented from being excessively heated. In addition, since the waste heat boiler 12 is not used to heat the white smoke prevention air, the amount of steam available for other heat utilization facilities such as the drying device 17 and the steam power generation device 18 is increased accordingly. Therefore, while effectively utilizing the steam generated in the waste heat boiler, the white smoke prevention air is prevented from being excessively heated by the white smoke prevention device, and the waste heat recovery efficiency can be improved.

[0079] Furthermore, in this embodiment, the controller 100A executes combined exhaust gas system control for controlling the flow rate of white smoke prevention air supplied to the exhaust gas heat exchanger 14 by the air supply unit 38 (the white smoke prevention blower 20, the upstream damper 31, and the downstream damper 32 in this example) so that the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection unit 70 becomes a white smoke prevention target temperature that is set to be equal to or higher than a lower limit temperature at which generation of white smoke from the chimney section 16 can be prevented.

[0080] According to this configuration, the combined exhaust gas control is executed by the controller 100A, so that the combined exhaust gas system temperature is controlled to the white smoke prevention target temperature. This white smoke prevention target temperature is set to a lower limit temperature at which the generation of white smoke from the chimney section 16 can be prevented (the minimum temperature required to prevent condensation of water vapor in the combined exhaust gas passing through the chimney section 16). Therefore, the generation of white smoke from the chimney section 16 can be reliably suppressed.

[0081] In addition, the controller 100A is capable of executing heat transfer system control to control the flow rate of white smoke prevention air supplied to the exhaust gas heat exchanger 14 by the air supply unit 38 (in this example, the white smoke prevention blower 20, the upstream damper 31, and the downstream damper 32) so that the temperature of the heat transfer section of the exhaust gas heat exchanger 14 detected by the heat transfer system temperature detection unit 71 becomes the heat transfer system target temperature, and is configured to execute the heat transfer system control every time before the air supply unit 38 executes the combined exhaust gas control.

[0082] According to this, under the control of the controller 100A, the heat transfer section control is executed with priority every time before the combined exhaust gas system control is executed. Therefore, even if the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger 14 by the air supply unit 38 increases due to the execution of the previous combined exhaust gas system control, and the temperature of the heat transfer section of the exhaust gas heat exchanger 14 falls below the heat transfer section target temperature, the heat transfer section control is always executed before the next combined exhaust gas system control is executed, and the supply amount of the white smoke prevention air by the air supply unit 38 is controlled so that the temperature of the heat transfer section becomes the heat transfer section target temperature. Therefore, the combined exhaust gas system control related to the temperature control of the white smoke prevention air can be executed while preventing an excessive temperature drop of the heat transfer section of the exhaust gas heat exchanger 14 and preventing corrosion of the heat transfer section, etc. It is not necessary to provide either the upstream damper 31 or the downstream damper 32. Moreover, without providing both the upstream damper 31 and the downstream damper 32, control may be performed only by changing the rotation speed of the white smoke prevention blower 20.

[0083] (Modification of the first embodiment) 6A is a flowchart showing an overall flow of white smoke prevention control in a modified example of the first embodiment. This white smoke prevention control differs from the first embodiment in that the controller 100A executes heat transfer section system control (step SB1) and combined exhaust gas system control (step SB2) in parallel. Here, "executing in parallel" means that the heat transfer section system control and the combined exhaust gas system control are executed in parallel independently of each other, rather than waiting for the end of the heat transfer section system control as in the first embodiment before executing the combined exhaust gas system control.

[0084] When the heat transfer section system control and the combined exhaust gas system control are executed in parallel in this way, there is a risk of interference between the operation of the air supply unit 38 based on the heat transfer section system control and the operation of the air supply unit 38 based on the combined exhaust gas system control. In this modified example, in order to avoid such interference in the operation of the air supply unit 38 and to protect (prevent corrosion) the heat transfer section and the like of the exhaust gas heat exchanger 14 by the heat transfer section system control, the controller 100A is configured to execute a priority control process that prioritizes the heat transfer section system control over the combined exhaust gas system control. This priority control process is executed in parallel with the heat transfer section system control and the combined exhaust gas system control.

[0085] 6B is a flowchart showing details of the priority control process. In this priority control process, during continuous operation of the incinerator 10, the temperature of the heat transfer section of the exhaust gas heat exchanger 14 is detected by the heat transfer section temperature detection unit 71, and the detected temperature information is received by the reception unit 101 (step SB3). Then, the detection data including the information on the temperature of the heat transfer section is input to the judgment unit 102 through the reception unit 101.

[0086] The determination unit 102 determines whether the temperature related to the detection data, i.e., the temperature of the heat transfer unit (one example of the heat transfer system temperature) detected by the heat transfer system temperature detection unit 71, is the heat transfer system target temperature (step SB4). If the determination unit 102 determines that the detected temperature of the heat transfer unit is not the heat transfer system target temperature (NO in step SB4), the flow rate adjustment unit 103 prohibits the operation of the air supply unit 38 based on the combined exhaust gas system control (step SB6), and the heat transfer Only the operation of the air supply unit 38 based on the combined exhaust gas system control is permitted. As a result, the operation of the air supply unit 38 based on the heat transfer system control is executed with priority over the operation of the air supply unit 38 based on the combined exhaust gas system control. On the other hand, if the determination unit 102 determines that the detected temperature of the heat transfer unit is the heat transfer system target temperature (YES in step SB4), the flow rate adjustment unit 103 permits the operation of the air supply unit 38 based on the combined exhaust gas system control (step SB5), and the operation of the air supply unit 38 based on the combined exhaust gas system control becomes executable.

[0087] [Effects] In this modified example, the controller 100A executes operation control of the air supply unit 38 based on combined exhaust gas system control and heat transfer unit system control, so that, as in the first embodiment, it is possible to prevent corrosion of the heat transfer units of the exhaust gas heat exchanger 14, while preventing the generation of white smoke caused by condensation of moisture in the combined exhaust gas.

[0088] Moreover, in this modification, the controller 100A executes the combined exhaust gas system control and the heat transfer section system control in parallel. Therefore, if the temperature of the heat transfer section of the exhaust gas heat exchanger 14 deviates from the heat transfer section system target temperature during the execution of the combined exhaust gas system control, the operation control of the air supply section 38 based on the combined exhaust gas system control is immediately prohibited and the operation control of the air supply section 38 based on the heat transfer section system control is executed preferentially. Therefore, compared with the case where the heat transfer section system control is executed after waiting for the completion of the currently executed combined exhaust gas system control as in the first embodiment, the execution timing of the heat transfer section system control when the temperature of the heat transfer section deviates from the heat transfer section system target temperature can be advanced. Therefore, the corrosion of the heat transfer section of the exhaust gas heat exchanger 14 can be more reliably suppressed.

[0089] Second embodiment Next, a second embodiment of the present invention will be described with reference to FIGS.

[0090] Fig. 7 shows a waste treatment facility 1B according to the second embodiment. The waste treatment facility 1B includes components corresponding to those included in the waste treatment facility 1A shown in Fig. 1, but differs from the first embodiment in the following points.

[0091] 1. Differences in the configuration of waste treatment facilities The waste treatment facility 1B further includes a heat recovery exchanger 60 and a heat exchange amount varying mechanism 39, unlike the first embodiment.

[0092] [Heat recovery exchanger and configuration related to the heat recovery exchanger] The heat recovery exchanger 60 is disposed in the white smoke prevention air downstream path section 30b of the white smoke prevention air supply path 30, and recovers heat from the white smoke prevention air after passing through the exhaust gas heat exchanger 14, i.e., the white smoke prevention air flowing through the white smoke prevention air downstream path section 30b, and uses the recovered heat to heat the supply boiler water to be supplied to the waste heat boiler 12.

[0093] The white smoke prevention air supply path 30 has a white smoke prevention upstream path section 30a and a white smoke prevention downstream path section 30b, as well as a recovery heat exchange bypass air path section 30c that bypasses the recovery heat exchanger 60. The recovery heat exchange bypass air path section 30c allows the white smoke prevention air sent from the white smoke prevention blower 20 to be supplied to the chimney section 16 without passing through the recovery heat exchanger 60.

[0094] Specifically, the upstream end of the heat recovery exchange bypass air passage section 30c is connected to an upstream connection section 30d provided upstream of the heat recovery exchanger 60 in the downstream passage section 30b, and the downstream end is connected to a downstream connection section 30e provided downstream of the heat recovery exchanger 60 in the downstream passage section 30b. An upstream damper 33 is disposed between the upstream connection section 30d and the heat recovery exchanger 60, a downstream damper 34 is disposed between the downstream connection section 30e and the heat recovery exchanger 60, and a bypass damper 35 is disposed in the heat recovery bypass air passage section 30c. The upstream damper 33, downstream damper 34, and bypass damper 35 constitute a part of a heat exchange amount variable mechanism 39, as described later.

[0095] The feedwater path 22 of the boiler water for supply to the waste heat boiler 12 has an upstream feedwater path section 22a located upstream of the heat recovery exchanger 60 and a downstream feedwater path section 22b located downstream. The upstream feedwater path section 22a connects the discharge port of the feedwater pump 23 and the water inlet of the heat recovery exchanger 60. The downstream feedwater path section 22b connects the water outlet of the heat recovery exchanger 60 and the water supply port of the waste heat boiler 12. The feedwater path 22 further has a bypass feedwater path section 22c that bypasses the heat recovery exchanger 60. The bypass feedwater path section 22c allows the supply boiler water sent from the feedwater pump 23 to be supplied to the waste heat boiler 12 without passing through the heat recovery exchanger 60. Specifically, the upstream end of the bypass water supply path section 22c is connected to an upstream connection section 22d provided at an intermediate position of the upstream water supply path section 22a, and the downstream end is connected to a downstream connection section 22e provided at an intermediate position of the downstream water supply path section 22b. An upstream water supply valve 27 is provided between the upstream connection section 22d and the heat recovery exchanger 60 in the upstream water supply path section 22a, a downstream water supply valve 28 is provided between the downstream connection section 22e and the heat recovery exchanger 60 in the downstream water supply path section 22b, and a bypass water supply valve 29 is provided at an intermediate portion of the bypass water supply path section 22c. The upstream water supply valve 27, the downstream water supply valve 28, and the bypass water supply valve 29 constitute a part of a heat exchange amount variable mechanism 39, as described later. All "valves" described in this specification are on-off valves having an opening that can be changed in response to a command signal input to the valve, and are configured to allow fluid to flow through the valve at a flow rate that corresponds to the opening.

[0096] [Configuration of variable heat exchange mechanism] The heat exchange volume variable mechanism 39 has an air volume change mechanism 39a for changing the flow rate of white smoke prevention air, which is the high-temperature fluid (heat recovery target) flowing into the heat recovery exchanger 60, and a heating target flow rate variable mechanism 39b for changing the flow rate of the supply boiler water, which is the low-temperature fluid (heat target fluid) flowing into the heat recovery exchanger 60.

[0097] The air amount change mechanism 39a has the upstream damper 33 and downstream damper 34 arranged on either side of the heat recovery exchanger 60 in the white smoke prevention downstream path section 30b, and the bypass side damper 35 arranged in the heat recovery bypass air path section 30c. The air amount change mechanism 39a is configured to change the ratio of the flow rate of the white smoke prevention air flowing into the heat recovery exchanger 60 and the flow rate of the white smoke prevention air flowing into the heat recovery bypass air path section 30c, among the white smoke prevention air that has passed through the exhaust gas heat exchanger 14, by changing the opening degree of the upstream damper 33, the downstream damper 34, and the bypass side damper 35 under the control of a controller 100B described later. This ratio is ultimately determined by the opening degree of each damper 33 to 35, and in this embodiment, the control signal transmitted from the controller 100 to each damper 33 to 35 of the air amount change mechanism 39a is a control signal related to the opening degree of each damper 33 to 35, not a control signal related to this ratio. Note that a control signal related to this ratio may be adopted as the control signal, and in this case, for example, the opening degree of each of the dampers 33 to 35 may be calculated backward from the ratio.

[0098] The heating target flow rate varying mechanism 39b has the upstream side feedwater valve 27 arranged in the upstream side feedwater path section 22a of the above-mentioned supply boiler water supply path 22, the downstream side feedwater valve 28 arranged in the downstream side feedwater path section 22b, and the bypass side feedwater valve 29 arranged in the bypass feedwater path section 22c. The heating target flow rate varying mechanism 39b is configured to be able to change the ratio of the flow rate of the supply boiler water flowing into the heat recovery exchanger 60 and the flow rate of the supply boiler water flowing into the bypass feedwater path section 22c, among the supply boiler water sent from the feedwater pump 23, by changing the opening degrees of the upstream side feedwater valve 27, the downstream side feedwater valve 28, and the bypass side feedwater valve 29 under the control of a controller 100B described later. This ratio is ultimately determined by the opening degree of each of the water supply valves 27 to 29, and in this embodiment, the control signal transmitted from the controller 100 to the heating target flow rate varying mechanism 39b is not a control signal related to this ratio, but a control signal related to the opening degree of each of the water supply valves 27 to 29. Note that a control signal related to this ratio may be adopted as the control signal, and in this case, for example, the opening degree of each of the water supply valves 27 to 29 may be calculated backwards from the ratio.

[0099] 2. Differences in control systems The waste treatment facility 1B according to the second embodiment includes a controller 100B shown in FIG. 8 instead of the controller 100A shown in FIG.

[0100] The controller 100B executes white smoke prevention control based on the respective temperatures detected by the combined exhaust gas system temperature detection unit 70 and the heat transfer system temperature detection unit 71, as in the first embodiment, but the content of the combined exhaust gas system control included in the white smoke prevention control is different from that in the first embodiment. That is, the combined exhaust gas system control of this embodiment does not adjust the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger 14 as in the first embodiment, but rather controls the temperature of the white smoke prevention air supplied to the chimney section 16 to the white smoke prevention target temperature by adjusting the amount of heat recovered from the white smoke prevention air in the recovery heat exchanger 60. The controller 100B in this embodiment corresponds to a heat exchange control unit.

[0101] The controller 100B further includes a heat exchange amount adjuster 104 (see FIG. 8) in addition to the reception unit 101, the determination unit 102, the flow rate adjuster 103, and the storage unit 110, which are similar functional units to those of the controller 100A in FIG.

[0102] In this embodiment, the heat transfer section system control is performed by the reception unit 101, the determination unit 102, and the flow rate adjustment unit 103, and the combined exhaust gas system control is performed by the reception unit 101, the determination unit 102, and the heat exchange amount adjustment unit 104. In this respect, the controller 100A of the first embodiment executes both the heat transfer section system control and the combined exhaust gas system control by the reception unit 101, the determination unit 102, and the flow rate adjustment unit 103.

[0103] That is, in the heat transfer system control of this embodiment, the flow rate adjusting unit 103 controls the operation of the air supply unit 38 so that the temperature detected by the heat transfer system temperature detecting unit 71 becomes the heat transfer system target temperature based on the output result of the determining unit 102. This heat transfer system control is similar to that of the first embodiment, and therefore a detailed description thereof will be omitted.

[0104] In the combined exhaust gas system control of the present embodiment, a heat exchange amount adjustment unit 104 controls the operation of the heat exchange amount variable mechanism 39 based on the output result of the determination unit 102 so that the temperature detected by the combined exhaust gas system temperature detection unit 70 becomes the white smoke prevention target temperature. Unlike the first embodiment, in this combined exhaust gas system control, the amount of white smoke prevention air supplied by the air supply unit 38 is maintained constant. Note that, unless the flow rate of the white smoke prevention air is restricted by the heat transfer system control, it is preferable to set the amount of white smoke prevention air supplied by the air supply unit 38 to the maximum flow rate (i.e. the rotation speed of the white smoke prevention blower 20 is maximum and the openings of the upstream damper 31 and downstream damper 32 are maximum).

[0105] The controller 100B repeats the process of executing the combined exhaust gas system control after executing the heat transfer section system control, as in the first embodiment. The content of the heat transfer section system control is the same as that in the first embodiment, so a detailed description thereof will be omitted, and the combined exhaust gas system control, the content of which is different from that in the first embodiment, will be described.

[0106] 9 is a flow chart showing details of the combined exhaust gas system control executed by the controller 100B. In this combined exhaust gas system control, during continuous operation of the incinerator 10, the temperature of the white smoke prevention air flowing in the downstream portion of the white smoke prevention air supply path 30 from the heat recovery exchanger 60 (one example of the combined exhaust gas system temperature) is detected by the combined exhaust gas system temperature detection unit 70, that is, the temperature of the white smoke prevention air after being heated in the exhaust gas heat exchanger 14 and then subjected to heat recovery processing in the heat recovery exchanger 60, and the detected temperature information is received by the reception unit 101 (step SC201). Then, the detection data including the information on the temperature of this white smoke prevention air is input to the judgment unit 102 through the reception unit 101.

[0107] The determination unit 102 determines whether or not the temperature related to the detection data, i.e., the temperature of the white smoke prevention air detected by the combined exhaust gas system temperature detection unit 70, is the white smoke prevention target temperature (step SC202). If the determination unit 102 determines that the detected temperature of the white smoke prevention air is not the white smoke prevention target temperature (NO in step SC202), the determination unit 102 further determines whether or not the detected temperature of the white smoke prevention air is lower than the white smoke prevention target temperature (step SC203).

[0108] Then, if the determination unit 102 determines that the temperature of the detected white smoke prevention air is lower than the white smoke prevention target temperature (YES in step SC203), the heat exchange amount adjustment unit 104 reduces the flow rate of the white smoke prevention air, which is the high-temperature fluid (heat recovery target) flowing into the recovery heat exchanger 60, by reducing the opening of the upstream damper 33 or the downstream damper 34 (see FIG. 7) on both sides of the recovery heat exchanger 60 and increasing the opening of the bypass damper 35 that bypasses the recovery heat exchanger 60, or reduces the flow rate of the supply boiler water, which is the low-temperature fluid (fluid to be heated) flowing into the recovery heat exchanger 60, by reducing the opening of the upstream feed water valve 27 or the downstream feed water valve 28 of the recovery heat exchanger 60 and increasing the opening of the bypass feed water valve 29 of the recovery heat exchanger 60 (step SC204). This reduces the amount of heat recovered from the white plume prevention air to the supply boiler water in the heat recovery exchanger 60, thereby increasing the temperature of the white plume prevention air.

[0109] On the other hand, when the judgment unit 102 judges that the temperature of the detected white smoke prevention air is higher than the white smoke prevention target temperature (NO in step SC203), the heat exchange amount adjustment unit 104 increases the opening degree of the upstream side damper 33 or downstream side damper 34 on both sides of the recovery heat exchanger 60 and decreases the opening degree of the bypass side damper 35 that bypasses the recovery heat exchanger 60 to increase the flow rate of the white smoke prevention air, which is a high-temperature side fluid (a target for heat recovery) flowing into the recovery heat exchanger 60, or increases the opening degree of the upstream side feed water valve 27 or downstream side feed water valve 28 of the recovery heat exchanger 60 and decreases the opening degree of the bypass side feed water valve 29 of the recovery heat exchanger 60 to increase the flow rate of the supply boiler water, which is a low-temperature side fluid (a fluid to be heated) flowing into the recovery heat exchanger 60 (step SC205). As a result, the amount of heat recovered from the white smoke prevention air to the supply boiler water in the recovery heat exchanger 60 is increased, and the temperature of the white smoke prevention air is lowered.

[0110] Then, after the processing of step SC204 or step SC205 is completed, the process returns to step SC201. The above operations are repeated until the detected temperature of the white smoke prevention air reaches the white smoke prevention target temperature (until a YES determination is made in step SC202). If the determination unit 102 determines in step SC202 that the detected temperature of the white smoke prevention air reaches the white smoke prevention target temperature (YES in step SC202), the combined exhaust gas system control (the processing of steps SC201 to SC205) is terminated, and the process returns to a step for executing heat transfer system control (corresponding to step SA1 in the first embodiment).

[0111] As an example of changing the opening degree of each damper 33-35, the opening degree of only the upstream damper 33 and the bypass side damper 35 may be changed, the downstream damper 34 may be always fully open, and the downstream damper 34 may be fully closed only when the upstream damper 33 is fully closed (when the entire amount of white smoke prevention air that has passed through the exhaust gas heat exchanger 14 and been supplied to the upstream connection portion 30d flows into the bypass air path portion 30c). As another example of changing the opening degree of each damper 33-35, the opening degree of only the downstream damper 34 and the bypass side damper 35 may be changed, the upstream damper 33 may be always fully open, and the upstream damper 33 may be fully closed only when the downstream damper 34 is fully closed (when the entire amount of white smoke prevention air that has passed through the exhaust gas heat exchanger 14 flows into the bypass air path portion 30c).

[0112] As an example of changing the opening degree of each of the feedwater valves 27-29, the opening degree of only the upstream side feedwater valve 27 and the bypass side feedwater valve 29 may be changed, the downstream side feedwater valve 28 may be kept fully open at all times, and the downstream side feedwater valve 28 may be fully closed only when the upstream side feedwater valve 27 is fully closed (when the entire amount of the supply boiler water sent from the feedwater pump 23 and supplied to the upstream side connection part 22d flows into the bypass feedwater path part 22c). As another example of changing the opening degree of each of the feedwater valves 27-29, the opening degree of only the downstream side feedwater valve 28 and the bypass side feedwater valve 29 may be changed, the upstream side feedwater valve 27 may be kept fully open at all times, and the upstream side feedwater valve 27 may be fully closed only when the downstream side feedwater valve 28 is fully closed (when the entire amount of the supply boiler water sent from the feedwater pump 23 and supplied to the upstream side connection part 22d flows into the bypass feedwater path part 22c).

[0113] [Effects] As described above, according to the waste treatment facility 1B of the second embodiment, as in the first embodiment, the exhaust gas heat exchanger 14 is disposed between the waste heat boiler 12 and the chimney portion 16 in the exhaust gas passage 50, and the white smoke prevention air is heated in the exhaust gas heat exchanger 14 by the heat of the relatively low temperature exhaust gas after passing through the waste heat boiler 12, thereby making it possible to prevent the white smoke prevention air from being excessively heated. Therefore, it is possible to prevent a decrease in waste heat recovery efficiency caused by the white smoke prevention air being excessively heated.

[0114] Moreover, according to the waste treatment facility 1B of the second embodiment, a recovery heat exchanger 60 is disposed in the white smoke prevention air supply path 30. The recovery heat exchanger 60 is configured to recover heat from the heated white smoke prevention air flowing through the white smoke prevention air supply path 30 and heat the supply boiler water to be supplied to the waste heat boiler 12 with the recovered heat, and the waste treatment facility 1B includes a heat exchange amount variable mechanism 39 that can change the inflow flow rate of the white smoke prevention air, which is the target of heat recovery flowing into the white smoke prevention air supply path 30, and the inflow flow rate of the supply boiler water, which is the target of heating. The waste treatment facility 1B further includes a controller 100B, and the controller 100B is configured to execute combined exhaust gas system control for controlling, by the heat exchange amount variable mechanism 39, the flow rate of the white smoke prevention air, which is the object of heat recovery flowing into the recovery heat exchanger 60, and the flow rate of the supply boiler water, which is the object of heating, so that the temperature of the white smoke prevention air downstream of the recovery heat exchanger 60 detected by the combined exhaust gas system temperature detection unit 70 (an example of the combined exhaust gas system temperature) becomes a white smoke prevention target temperature that is set to be equal to or higher than a lower limit temperature at which the generation of white smoke from the chimney section 16 can be prevented.

[0115] According to this configuration, when the temperature of the white smoke prevention air after passing through the exhaust gas heat exchanger 14 is higher than the temperature necessary to prevent the generation of white smoke, the controller 100B controls the operation of the heat exchange amount variable mechanism 39 to recover the excess heat held by the white smoke prevention air to the supply boiler water in the heat recovery exchanger 60, thereby preventing a decrease in waste heat recovery efficiency caused by the white smoke prevention air being supplied to the chimney section 16 at an excessively high temperature. In addition, because the temperature of the supply boiler water is raised, the amount of steam generated in the waste heat boiler 12 increases.

[0116] In the second embodiment, the controller 100B is configured to execute the heat transfer system control every time before the air supply control unit executes the combined exhaust gas control, similarly to the first embodiment.

[0117] Therefore, similarly to the first embodiment, it is possible to prevent the generation of white smoke from the chimney portion 16 while preventing corrosion of the heat transfer portion of the exhaust gas heat exchanger 14 and the like.

[0118] (First modified example of the second embodiment) Fig. 10 is a view corresponding to Fig. 8 (Fig. 1) showing a first modified example of the second embodiment. In this modified example, the fluid to be heated in the heat exchange amount variable mechanism 39 is combustion air, and the configuration of the heated object flow rate variable mechanism 39b, which is a part of the heat exchange amount variable mechanism 39, is different from that of the second embodiment.

[0119] That is, in this modified example, the heating target flow rate varying mechanism 39b is configured to have a first damper 42, a second damper 43, and a third damper 44 arranged in the combustion air supply path 40.

[0120] Specifically, the combustion air supply path 40 has an upstream air path section 40a located upstream of the heat recovery exchanger 60 and a downstream air path section 40b located downstream, unlike the second embodiment. The upstream air path section 40a connects the discharge port of the combustion air blower 19 and the air inlet of the heat recovery exchanger 60. The downstream air path section 40b connects the air outlet of the heat recovery exchanger 60 and the air inlet of the combustion air preheater 11. The combustion air supply path 40 further has a combustion air bypass path section 40c that bypasses the heat recovery exchanger 60. The combustion air bypass path section 40c allows the combustion air supplied from the combustion air blower 19 to be supplied to the combustion air preheater 11 without passing through the heat recovery exchanger 60. Specifically, the combustion air bypass path section 40c has an upstream end connected to an upstream connection section 40d provided at an intermediate position of the upstream air path section 40a, and a downstream end connected to a downstream connection section 40e provided at an intermediate position of the downstream air path section 40b. A first damper 42 is provided between the upstream connection section 40d and the heat recovery exchanger 60 in the upstream air path section 40a, a second damper 43 is provided between the downstream connection section 40e and the heat recovery exchanger 60 in the downstream air path section 40b, and a third damper 44 is provided at an intermediate portion of the combustion air bypass path section 40c. The first damper 42, the second damper 43, and the third damper 44 constitute the heating target flow rate varying mechanism 39b, and each damper 42 to 44 is controlled by a heat exchange amount adjusting section 104.

[0121] The specific details of the processing content of the combined exhaust gas control in this modified example are similar to the processing in steps SC204 and SC205 of Figure 9, in which the "upstream or downstream water supply valve of the recovery heat exchanger" is replaced with the "first or second damper" and the "bypass side water supply valve" is replaced with the "third damper", and therefore detailed explanations will be omitted here to avoid duplication.

[0122] According to this modified example, the only difference from the second embodiment is that the fluid to be heated in the heat exchange amount variable mechanism 39 is combustion air, and the other control processes are the same as those of the second embodiment, so that the same effects as those of the second embodiment can be obtained.

[0123] (Second modified example of the second embodiment) In a second modification of the second embodiment, the fluid to be heated in the heat exchange amount variable mechanism 39 is hot water (or air) for heating the dewatered sludge to be fed into the incinerator 10. In this modification, in order to heat the dewatered sludge, the pipe wall of the piping through which the dewatered sludge flows is made to have a double structure, and hot water is circulated between the outer pipe wall and the inner pipe wall. The heated target flow rate variable mechanism 39b is configured to be able to change the inflow amount of the hot water into the recovery heat exchanger 60. The control in this case is the same as that of the second embodiment, except that the boiler water in the second embodiment is replaced with hot water for heating the dewatered sludge, and therefore the same action and effect as that of the second embodiment can be obtained.

[0124] (Another modification of the second embodiment) As another modification of the second embodiment, the controller 100B may be configured to execute the heat transfer section system control by the air supply unit 38 and the combined exhaust gas system control by the heat exchange amount variable mechanism 39 in parallel. In this case, there is no need to separately execute the priority control process as in the modification of the first embodiment. That is, the control actuator of the heat transfer section system control executed by the controller 100B of this modification is the air supply unit 38, whereas the control actuator of the combined exhaust gas system control is the heat exchange amount variable mechanism 39, and the control actuators are different between the heat transfer section system control and the combined exhaust gas system control. Therefore, even if the heat transfer section system control and the combined exhaust gas system control are executed in parallel, conflicting operation commands are not issued to the same control actuator. Therefore, the combined exhaust gas system control and the heat transfer section system control can be executed in parallel without separately executing the priority control process.

[0125] [Effects] According to this modified example, under the control of the controller 100B, the heat transfer system control by the air supply unit 38 and the combined exhaust gas system control by the heat exchange amount variable mechanism 39 are executed, so that the same action effects as those of the second embodiment can be obtained.

[0126] In addition, in this modification, the heat transfer section control and the combined exhaust gas system control are executed in parallel by the controller 100B, so that the execution timing of the heat transfer section control when the temperature of the heat transfer section of the exhaust gas heat exchanger 14 deviates from the heat transfer section target temperature can be made earlier than the case where the heat transfer section control is executed after waiting for the completion of the combined exhaust gas system control as in the second embodiment. Therefore, corrosion of the heat transfer section of the exhaust gas heat exchanger 14 can be more reliably suppressed.

[0127] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS.

[0128] Fig. 11 shows a waste treatment facility 1C according to the third embodiment. The waste treatment facility 1C includes components corresponding to those included in the waste treatment facility 1A shown in Fig. 1, but differs from the first embodiment in the following points.

[0129] 1. Differences in the configuration of waste treatment facilities The waste treatment facility 1C further includes a steam heat exchanger 65 and a steam-side air amount varying mechanism 37, unlike the first embodiment.

[0130] [Steam heat exchanger and configuration related to the steam heat exchanger] The steam heat exchanger 65 is disposed in a main bypass air path 36 (an example of a bypass path) that is connected to the white smoke prevention air supply path 30 and bypasses the exhaust gas heat exchanger 14. The steam heat exchanger 65 is connected to the waste heat boiler 12 via a steam supply path 25c, and a portion of the steam generated in the waste heat boiler 12 is supplied to the steam heat exchanger 65 through the steam supply path 25c. The steam heat exchanger 65 transfers the heat of the steam supplied from the waste heat boiler 12 to the white smoke prevention air flowing through the main bypass air path 36, thereby heating the white smoke prevention air.

[0131] The main bypass air path 36 has an upstream air path section 36a located upstream of the steam heat exchanger 65 and a downstream air path section 36b located downstream of the steam heat exchanger 65. The upstream end of the upstream air path section 36a is connected to a connection section 36c located between the downstream damper 32 in the bypass air supply path 30 and an exhaust gas heat exchanger side damper 37b described later, and the downstream end is connected to the air inlet of the steam heat exchanger 65. A steam heat exchanger side damper 37a described later is provided in the middle of the upstream air path section 36a. The downstream air path section 36b has an upstream end connected to the air outlet of the steam heat exchanger 65 and a downstream end connected to a connection section 30f provided in the bypass downstream path section 30b.

[0132] The steam-side air amount varying mechanism 37 is a mechanism for changing the flow rate of the white smoke prevention air flowing from the white smoke prevention air supply path 30 to the steam heat exchanger 65 provided in the main bypass air path 36, and is constituted by the steam heat exchange side damper 37a in this embodiment. In addition, an exhaust gas heat exchange side damper 37b is disposed downstream of a connection portion 36c with the upstream end of the upstream air path portion 36a in the white smoke prevention upstream path portion 30a. In this embodiment, the opening degree of the exhaust gas heat exchange side damper 37b is maintained constant at a maximum, for example, but is not limited thereto. For example, the opening degree of the exhaust gas heat exchange side damper 37b may be changed to change the flow rate of the white smoke prevention air flowing into the steam heat exchanger 65. In this case, the exhaust gas heat exchange side damper 37b and the steam heat exchange side damper 37a constitute the steam-side air amount varying mechanism 37.

[0133] The opening degree of the steam heat exchange side damper 37a is changed by a controller 100C described later. When the steam heat exchange side damper 37a is open, a part of the white smoke prevention air flowing through the white smoke prevention air supply path 30 flows into the main bypass air path 36, passes through the steam heat exchange side damper 37a, and is then supplied to the steam heat exchanger 65. The white smoke prevention air supplied to the steam heat exchanger 65 is heated in the steam heat exchanger 65, reaches the connection portion 30f, and merges with the white smoke prevention air after passing through the exhaust gas heat exchanger 14 (i.e., the white smoke prevention air flowing through the white smoke prevention downstream path portion 30b) at the connection portion 30f. Here, the temperature of the steam used as the high-temperature side fluid in the steam heat exchanger 65 is higher than the temperature of the exhaust gas used as the high-temperature side fluid in the exhaust gas heat exchanger 14, so the steam heat exchanger 65 has a higher heating capacity for the white smoke prevention air than the exhaust gas heat exchanger 14. Therefore, the more the opening degree of the steam heat exchange side damper 37a is increased, the more the amount of white smoke prevention air inflowing into the steam heat exchanger 65, which has a high heating capacity, increases compared to the amount of white smoke prevention air inflowing into the exhaust gas heat exchanger 14, which has a low heating capacity, and as a result, the temperature of the white smoke prevention air after merging at the connection part 30f increases.

[0134] 2. Differences in control systems The waste treatment facility 1C according to the third embodiment includes a controller 100C shown in FIG. 12 instead of the controller 100A shown in FIG.

[0135] The controller 100C executes white smoke prevention control based on the respective detection target temperatures of the combined exhaust gas system temperature detection unit 70 and the heat transfer system temperature detection unit 71, as in the first embodiment, but the content of the combined exhaust gas system control constituting a part of the white smoke prevention control is different from that in the first embodiment. That is, in the combined exhaust gas system control of this embodiment, the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger 14 is not adjusted as in the first embodiment, but the flow rate of the white smoke prevention air to the steam heat exchanger 65 arranged in the main bypass air path 36 is adjusted to control the temperature of the white smoke prevention air supplied to the chimney unit 16 (an example of the combined exhaust gas system temperature) to the white smoke prevention target temperature. The controller 100C in this embodiment corresponds to a steam side air amount control unit.

[0136] Specifically, the controller 100C includes functional units similar to those of the controller 100A in FIG. 2, namely, a reception unit 101, a judgment unit 102, a flow rate adjustment unit 103, and a memory unit 110 (see FIG. 12), but differs from FIG. 2 in that a steam heat exchanger side damper 37a is further added as a control actuator by the flow rate adjustment unit 103.

[0137] In this embodiment, similarly to the first embodiment, the heat transfer section system control and the combined exhaust gas system control are executed by the reception unit 101, the determination unit 102, and the flow rate adjustment unit 103. The content of the heat transfer section system control is similar to that of the first embodiment, but the content of the combined exhaust gas system control is different from that of the first embodiment.

[0138] That is, in the combined exhaust gas system control of this embodiment, the flow rate adjustment unit 103 controls the opening of the steam heat exchange side damper 37a based on the output result of the determination unit 102 so that the temperature detected by the combined exhaust gas system temperature detection unit 70 becomes the white smoke prevention target temperature. In addition, the flow rate adjustment unit 103 controls the rotation speed of the white smoke prevention blower 20 or the opening of the upstream damper 31 so that the flow rate of white smoke prevention air supplied to the exhaust gas heat exchanger 14 is constant even if the opening of the steam heat exchanger side damper 37a is changed.

[0139] The controller 100C repeats the process of executing the combined exhaust gas system control after executing the heat transfer system control, as in the first embodiment. In the following, the combined exhaust gas system control, which is different from the first embodiment, will be described, and the heat transfer system control will not be described because it is the same as the first embodiment.

[0140] 13 is a flow chart showing details of the combined exhaust gas system control in the third embodiment. In this combined exhaust gas system control, during continuous operation of the incinerator 10, the temperature of the white smoke prevention air flowing in the downstream portion of the connection portion 30f in the white smoke prevention air supply path 30 (one example of the combined exhaust gas system temperature), that is, the temperature of the white smoke prevention air obtained by combining the white smoke prevention air heated in the steam heat exchanger 65 and the white smoke prevention air heated in the exhaust gas heat exchanger 14, is detected by the combined exhaust gas system temperature detection unit 70, and the detected temperature information is received by the reception unit 101 (step SD201). Then, the detection data including the information on the temperature of this white smoke prevention air is input to the judgment unit 102 through the reception unit 101.

[0141] The determination unit 102 determines whether or not the temperature related to the detection data, i.e., the temperature of the white smoke prevention air detected by the combined exhaust gas system temperature detection unit 70, is the white smoke prevention target temperature (step SD202). If the determination unit 102 determines that the detected temperature of the white smoke prevention air is not the white smoke prevention target temperature (NO in step SD202), the determination unit 102 further determines whether or not the detected temperature of the white smoke prevention air is lower than the white smoke prevention target temperature (step SD203).

[0142] Then, when the determination unit 102 determines that the detected temperature of the white smoke prevention air is lower than the white smoke prevention target temperature (YES in step SD203), the flow rate adjustment unit 103 increases the opening degree of the steam heat exchange side damper 37a to increase the flow rate of the white smoke prevention air flowing into the steam heat exchanger 65 (step SD204). This increases the flow rate of the white smoke prevention air passing through the steam heat exchanger 65, which has a higher air heating capacity than the exhaust gas heat exchanger 14, and thus increases the temperature of the white smoke prevention air in the downstream portion of the connection portion 30f (the temperature of the white smoke prevention air immediately before being supplied to the chimney portion 16). Note that in step SD204, the opening degree of the exhaust gas heat exchange side damper 37b may be decreased together with the increase in the opening degree of the steam heat exchange side damper 37a.

[0143] On the other hand, when the determination unit 102 determines that the detected temperature of the white smoke prevention air is higher than the white smoke prevention target temperature (NO in step SD203), the flow rate adjustment unit 103 reduces the opening degree of the steam heat exchange side damper 37a to reduce the flow rate of the white smoke prevention air flowing into the steam heat exchanger 65 (step SD205). This reduces the flow rate of the white smoke prevention air passing through the steam heat exchanger 65, which has a higher air heating capacity than the exhaust gas heat exchanger 14, and thus reduces the temperature of the white smoke prevention air in the downstream portion of the connection portion 30f (the temperature of the white smoke prevention air immediately before being supplied to the chimney portion 16). Note that in step SD205, the opening degree of the exhaust gas heat exchange side damper 37b may be increased together with the reduction in the opening degree of the steam heat exchange side damper 37a. After the processing of step SD204 or step SD205, the rotation speed of the white smoke prevention blower 20 is changed so as to compensate for the change in the inflow flow rate of the white smoke prevention air to the exhaust gas heat exchanger 14 caused by the change in the opening degree of the steam heat exchange side damper 37a, in other words, so that the flow rate of the white smoke prevention air to the exhaust gas heat exchanger 14 is maintained at a preset set flow rate (step SD206). After the processing of this step SD206, the process returns to step SD201. The above operation is repeated until the temperature of the detected white smoke prevention air reaches the white smoke prevention target temperature (until YES is determined in step SD202). In step SD202, when the determination unit 102 determines that the temperature of the detected white smoke prevention air reaches the white smoke prevention target temperature (YES in step SD202), the combined exhaust gas system control (processing of steps SD201 to SD206) is terminated, and the process returns to the step for executing the heat transfer system control (corresponding to step SA1 in the first embodiment).

[0144] [Effects] As described above, according to the waste treatment facility 1C of the third embodiment, as in the first embodiment, the exhaust gas heat exchanger 14 is disposed downstream of the waste heat boiler 12 in the exhaust gas passage 50, and the white smoke prevention air is heated in the exhaust gas heat exchanger 14 by the heat of the relatively low-temperature exhaust gas after passing through the waste heat boiler 12, thereby making it possible to prevent the white smoke prevention air from being excessively heated. This makes it possible to prevent a decrease in waste heat recovery efficiency caused by the white smoke prevention air being excessively heated.

[0145] In the third embodiment, the waste treatment facility 1C includes a main bypass air path 36 that branches off from the white smoke prevention air supply path 30 through which the white smoke prevention air flows, bypassing the exhaust gas heat exchanger 14 and supplying the white smoke prevention air to the chimney section 16, a steam heat exchanger 65 disposed in the main bypass air path 36, and a steam heat exchanger side damper 37a (an example of a steam side air amount variable mechanism 37) that can change the flow rate of the white smoke prevention air flowing from the white smoke prevention air supply path 30 into the steam heat exchanger 65. The steam heat exchanger 65 is configured to transfer a portion of the heat of the steam generated in the waste heat boiler 12 to the white smoke prevention air flowing through the main bypass air path 36, thereby heating the white smoke prevention air. The waste treatment facility 1C further includes a controller 100C, and the controller 100C is configured to control the flow rate of white smoke prevention air flowing from the white smoke prevention air supply path 30 through the main bypass air path 36 to the steam heat exchanger 65, by the steam heat exchanger side damper 37a, so that the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection unit 70 becomes a white smoke prevention target temperature that is set to be equal to or higher than a lower limit temperature at which generation of white smoke from the chimney section 16 can be prevented.

[0146] According to this configuration, when the temperature of the white smoke prevention air after passing through the exhaust gas heat exchanger 14 is lower than the white smoke prevention target temperature, the opening of the steam heat exchanger side damper 37a is increased under the control of the controller 100C, so that part of the white smoke prevention air is guided to the steam heat exchanger 65, which has a higher air heating power than the exhaust gas heat exchanger 14, and the temperature of the white smoke prevention air after the white smoke prevention air heated by the steam heat exchanger 65 and the white smoke prevention air heated by the exhaust gas heat exchanger 14 join (i.e., the white smoke prevention air immediately before being supplied to the chimney section 16) can be raised to the white smoke prevention target temperature. In other words, by heating part of the white smoke prevention air supplied to the chimney section 16 by the steam heat exchanger 65 and heating the remaining white smoke prevention air by the exhaust gas heat exchanger 14 using low-temperature exhaust gas, excessive heating of the white smoke prevention air can be prevented and waste heat recovery efficiency can be improved compared to the conventional case in which all of the white smoke prevention air is overheated with high-temperature steam.

[0147] (Modification of the third embodiment) As a modification of the third embodiment, the controller 100C may be configured to execute the heat transfer section system control and the combined exhaust gas system control in parallel. In this case, as in the modification of the first embodiment, the controller 100C must separately execute a priority control process. That is, the control actuator of the heat transfer section system control executed by the controller 100C in this modification is the air supply unit 38, and the control actuator of the combined exhaust gas system control includes the white smoke prevention blower 20 (see step SD206) constituting the air supply unit 38. Therefore, when the heat transfer section system control and the combined exhaust gas system control are executed in parallel, there is a risk that conflicting operation commands are issued to the white smoke prevention blower 20 of the air supply unit 38 that is used in common in both controls. In this modification, the controller 100C executes a priority control process to avoid such a situation and prioritize the protection of the heat transfer section by the heat transfer section system control. In this priority control process, as in the modified example of the first embodiment, if the judgment unit 102 determines that the temperature of the heat transfer section is not the heat transfer section target temperature, the execution of the combined exhaust gas system control is prohibited, and if the judgment unit 102 determines that the temperature of the heat transfer section is the heat transfer section target temperature, the execution of the combined exhaust gas system control is permitted.

[0148] [Effects] According to this modified example, under the control of the controller 100C, heat transfer system control by the air supply unit 38 and combined exhaust gas system control by the steam side air amount variable mechanism 37 are executed, so that the same action effects as those of the third embodiment can be obtained.

[0149] Moreover, in this modification, the heat transfer section control and the combined exhaust gas system control are executed in parallel by the controller 100C, so that the execution timing of the heat transfer section control when the temperature of the heat transfer section of the exhaust gas heat exchanger 14 deviates from the heat transfer section target temperature can be made earlier than the case where the heat transfer section control is executed after waiting for the combined exhaust gas system control to be completed as in the third embodiment. Therefore, corrosion of the heat transfer section of the exhaust gas heat exchanger 14 can be more reliably suppressed.

[0150] (Other embodiments) The waste treatment facility according to the present invention is not necessarily limited to the above-mentioned configuration. For example, the following configuration may be adopted for the waste treatment facility according to the present invention.

[0151] (1) In each of the above-described embodiments and modifications, the waste treatment facilities 1A to 1C are configured to include the combustion air preheater 11, the dust collector 13, and the flue gas treatment tower 15 in addition to the incinerator 10, the waste heat boiler 12, and the chimney section 16, but are not limited to such a configuration. The combustion air preheater 11, the dust collector 13, and the flue gas treatment tower 15 are not necessarily required, and any configuration may be used as long as the incinerator 10, the waste heat boiler 12, and the chimney section 16 are included.

[0152] (2) In each of the above-described embodiments and modified examples, the white smoke prevention air is supplied to the chimney section 16, but the present invention is not limited to this and may be supplied, for example, to the outside of the outlet of the chimney section 16. In this case, if the supply position of the white smoke prevention air is far from the outlet of the chimney section 16, moisture in the exhaust gas will condense before the white smoke prevention air joins with the exhaust gas discharged from the outlet, causing white smoke, so the supply position of the white smoke prevention air is set within a predetermined range from the outlet of the chimney section 16 so as to prevent the generation of such white smoke. This predetermined range may be determined, for example, by conducting an operational test in advance.

[0153] (3) In each of the above embodiments and modified examples, the white smoke prevention air is supplied directly to the chimney section 16, but it is not necessarily required to supply it directly. For example, the white smoke prevention air may be introduced into the sixth path section 56 connecting the flue gas treatment tower 15 and the chimney section 16, and the white smoke prevention air may be supplied to the chimney section 16 via the sixth path section 56.

[0154] (4) In each of the above-described embodiments and modified examples, PID control may be performed when controlling the temperature of the heat transfer section of the exhaust gas heat exchanger 14 (an example of a heat transfer section temperature) to a heat transfer section target temperature. Similarly, PID control may be performed when controlling the temperature of the white smoke prevention air (an example of a combined exhaust gas system temperature) to a white smoke prevention target temperature.

[0155] (5) In the second embodiment and its modified example, the heat exchange amount varying mechanism 39 is configured to be able to change both the inflow flow rate of the white smoke prevention air, which is the heat recovery target flowing into the recovery heat exchanger 60, and the inflow flow rate of the supply boiler water, which is the heat recovery target. However, this is not limited to this, and it is sufficient that the heat exchange amount varying mechanism 39 is configured to be able to change at least one of them. That is, for example, the air amount changing mechanism 39a may be eliminated and only the inflow flow rate of the supply boiler water, which is the heat recovery target, may be eliminated and only the inflow flow rate of the white smoke prevention air, which is the heat recovery target, may be eliminated. It goes without saying that the configurations of the air amount changing mechanism 39a and the heating target flow rate varying mechanism 39b are not limited to the configurations of FIG. 7 described above. That is, for example, for the air amount changing mechanism 39a, either one of the upstream damper 33 and the downstream damper 34 may be eliminated. Also, for example, for the heating target flow rate varying mechanism 39b, either one of the upstream feed water valve 27 and the downstream feed water valve 28 may be eliminated.

[0156] (6) In the third embodiment and its modified examples, the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger 14 is kept constant by executing the process of step S206D, but the present invention is not limited to this. For example, the process of step SD206 may be eliminated and the flow rate of the white smoke prevention air supplied to the chimney portion 16 (i.e., the sum of the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger 14 and the flow rate of the white smoke prevention air supplied to the steam heat exchanger 65) may be kept constant. In this case, the rotation speed of the white smoke prevention blower 20 may be kept constant (for example, the maximum rotation speed), and the opening degrees of the upstream damper 31 and the downstream damper 32 may also be kept constant.

[0157] (7) The present invention includes any combination of the above-described embodiments and modifications.

[0158] The embodiments disclosed herein are illustrative in all respects and should not be construed as limiting. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0159] 1A Waste treatment facility 1B Waste treatment facility 1C Waste treatment facility 10 Incinerator 12 Waste heat boiler 14 Exhaust gas heat exchanger 16 Chimney section 20 White smoke prevention blower (air supply unit) 30 White air supply channel 37 Steam side air volume variable mechanism 37a Steam heat exchange side damper (steam side air volume variable mechanism) 38 Air supply section 31 Upstream damper (air supply section) 32 Downstream damper (air supply section) 39 Variable heat exchange mechanism 39a Air volume change mechanism (variable heat exchange mechanism) 39b Water volume change mechanism (variable heat exchange mechanism) 50 Exhaust gas route 60 Recovery heat exchanger 65 Steam heat exchanger 70 Combined exhaust gas temperature detector 71 Heat transfer system temperature detection unit 100A Controller (Air supply control unit) 100B Controller (air supply control unit, heat exchange control unit) 100C Controller (Air supply control unit, Steam side air volume control unit)

Claims

1. A waste treatment facility for treating waste, comprising: an incinerator for incinerating the waste; An exhaust gas path through which exhaust gas discharged from the incinerator flows; A chimney portion that discharges the exhaust gas to an external space; a waste heat boiler disposed in the exhaust gas passage and using the exhaust gas flowing through the exhaust gas passage as a heat source; an exhaust gas heat exchanger that is disposed downstream of the waste heat boiler in the exhaust gas path and includes a heat transfer unit that transfers heat of the exhaust gas, the temperature of which has been reduced by passing through the waste heat boiler, to white smoke prevention air that is to be heated, thereby heating the white smoke prevention air; a white smoke prevention air supply path for supplying the white smoke prevention air to be heated to the exhaust gas heat exchanger and supplying the white smoke prevention air heated by passing through the exhaust gas heat exchanger to the chimney section; An air supply unit that supplies the white smoke prevention air to be heated to the exhaust gas heat exchanger through the white smoke prevention air supply path; A waste treatment facility equipped with the following:

2. The waste treatment facility according to claim 1, a heat transfer system temperature detection unit that detects a temperature of the heat transfer section of the exhaust gas heat exchanger itself or a temperature having a correlation with the temperature as a heat transfer system temperature; An air supply control unit; The air supply control unit executes heat transfer system control to control the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit so that the heat transfer system temperature detected by the heat transfer system temperature detection unit becomes a preset heat transfer system target temperature.

3. The waste treatment facility according to claim 1, a combined exhaust gas system temperature detection unit that detects a temperature of the combined exhaust gas itself obtained by combining the heated white smoke prevention air supplied from the white smoke prevention air supply path in the chimney unit with the exhaust gas or a temperature that is correlated with the temperature of the combined exhaust gas system; An air supply control unit; The air supply control unit performs combined exhaust gas system control to control the flow rate of white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit so that the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection unit becomes a white smoke prevention target temperature that is set to be higher than or equal to a lower limit temperature at which white smoke can be prevented from being generated from the chimney.

4. The waste treatment facility according to claim 3, A heat transfer system temperature detection unit detects a temperature of the heat transfer section of the exhaust gas heat exchanger itself or a temperature having a correlation with the temperature as a heat transfer system temperature, The air supply control unit determines whether the heat transfer system temperature detected by the heat transfer system temperature detection unit is a preset heat transfer system target temperature each time before executing the combined exhaust gas system control, and if it determines that the detected heat transfer system temperature is not the heat transfer system target temperature, executes heat transfer system control to control the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit so that the heat transfer system temperature becomes the heat transfer system target temperature, and executes the combined exhaust gas system control after executing the heat transfer system control.

5. The waste treatment facility according to claim 3, A heat transfer system temperature detection unit detects a temperature of the heat transfer section of the exhaust gas heat exchanger itself or a temperature having a correlation with the temperature as a heat transfer system temperature, The air supply control unit is configured to execute heat transfer unit system control, which controls the flow rate of the white smoke prevention air supplied to the exhaust gas heat exchanger by the air supply unit, so that the heat transfer unit system temperature detected by the heat transfer unit system temperature detection unit becomes a predetermined heat transfer unit system target temperature, in parallel with the combined exhaust gas system control, and the waste treatment equipment is further configured to be capable of executing priority control processing for executing the heat transfer unit system control in priority to the combined exhaust gas system control to avoid a situation in which the operation of the air supply unit based on the combined exhaust gas system control interferes with the operation of the air supply unit based on the heat transfer unit system control.

6. The waste treatment facility according to claim 1 or 2, a heat recovery exchanger disposed in the white smoke prevention air supply path, recovering heat from the heated white smoke prevention air flowing through the white smoke prevention air supply path, and using the recovered heat to heat a fluid to be heated, which is one of the supply boiler water to be supplied to the waste heat boiler, the combustion air to be supplied to the incinerator, and a fluid for heating the waste to be fed into the incinerator; a heat exchange amount varying mechanism capable of changing at least one of a flow rate of the white smoke prevention air, which is a heat recovery target flowing into the heat recovery exchanger, and a flow rate of the fluid to be heated.

7. The waste treatment facility according to claim 6, a combined exhaust gas system temperature detection unit that detects a temperature that is correlated with a temperature of a combined exhaust gas obtained by combining the heated white smoke prevention air supplied from the white smoke prevention air supply path in the chimney unit and the exhaust gas as a combined exhaust gas system temperature; A heat exchange control unit; The heat exchange control unit performs combined exhaust gas system control by controlling at least one of the flow rate of white smoke prevention air, which is a heat recovery target flowing into the heat recovery exchanger, and the flow rate of the fluid to be heated, using the heat exchange amount variable mechanism, so that the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection unit becomes a white smoke prevention target temperature that is set to be equal to or higher than a lower limit temperature at which white smoke can be prevented from being generated from the chimney.

8. The waste treatment facility according to claim 1 or 2, A bypass path that branches off from the white smoke prevention air supply path and bypasses the exhaust gas heat exchanger to supply white smoke prevention air to the chimney section; a steam heat exchanger provided in the bypass path and configured to transfer heat of a portion of the steam generated in the waste heat boiler to the white smoke prevention air flowing through the bypass path, thereby heating the white smoke prevention air; a steam-side air amount varying mechanism capable of changing a flow rate of the white smoke prevention air flowing from the white smoke prevention air supply path through the bypass path to the steam heat exchanger.

9. The waste treatment facility according to claim 8, a combined exhaust gas system temperature detection unit that detects a temperature that is correlated with a temperature of a combined exhaust gas obtained by combining the heated white smoke prevention air supplied from the white smoke prevention air supply path and the bypass path and the exhaust gas in the chimney as a combined exhaust gas system temperature; A steam side air amount control unit is provided. The steam-side air volume control unit executes combined exhaust gas system control to control the flow rate of white smoke prevention air flowing from the white smoke prevention air supply path through the bypass path to the steam heat exchanger, using the steam-side air volume variable mechanism, so that the combined exhaust gas system temperature detected by the combined exhaust gas system temperature detection unit becomes a white smoke prevention target temperature that is set to be equal to or higher than a lower limit temperature at which white smoke can be prevented from being generated from the chimney.

10. The waste treatment facility according to claim 1, The steam generated in the waste heat boiler is supplied to another heat utilization facility for a purpose other than the purpose of using the steam for heating the white smoke prevention air.

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