Waste treatment equipment and waste treatment methods

Abstract

To prevent corrosion in a heat exchanger disposed on an exhaust gas passage while increasing a temperature of a heat exchange gas obtained by heat exchange with a gas, to prevent severe restriction on a position of the heat exchanger at an upstream side on the exhaust gas passage, and further to prevent operating conditions of an incinerator from becoming severe.SOLUTION: A waste treatment plant 1 includes: a white smoke prevention preliminary heat exchanger 12 disposed at an upstream side of a wet type smoke washing device 14 on an exhaust gas passage 4 and heating the air by heat exchange between the exhaust gas before the wet smoke washing treatment and the air as a heat exchange gas; and a white smoke prevention main heat exchanger 8 disposed at an upstream side of the white smoke prevention preliminary heat exchanger 12 for further heating the air heated by the white smoke prevention preliminary heat exchanger 12 by the heat exchange with the exhaust gas. The white smoke prevention preliminary heat exchanger 12 has a corrosion preventing function portion 15 for preventing corrosion of a part defining a preliminary heat exchanger exhaust gas flow channel 47.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to waste treatment equipment and a waste treatment method.

Background Art

[0002] Conventionally, there is known waste treatment equipment configured to incinerate waste in an incinerator and recover heat from the exhaust gas generated by the incineration of the waste. Patent Document 1 below discloses an example of such waste treatment equipment.

[0003] The waste treatment equipment disclosed in Patent Document 1 below includes an incinerator, a combustion air preheater, a two-stage high-temperature heat exchanger, a wet flue gas treatment device, and a low-temperature heat exchanger. An exhaust gas path composed of a series of a plurality of gas ducts is connected to the gas outlet of the incinerator, and the exhaust gas discharged from the incinerator flows into this exhaust gas path. The incinerator, the combustion air preheater, the two-stage high-temperature heat exchanger, the wet flue gas treatment device, and the low-temperature heat exchanger are arranged in this order from the upstream side to the downstream side on the exhaust gas path.

[0004] In the low-temperature heat exchanger, exhaust gas treated by a wet flue gas treatment system and air supplied by a forced-air blower are introduced. Heat exchange takes place between the introduced air and the exhaust gas in the low-temperature heat exchanger. The air heated by this heat exchange is discharged from the low-temperature heat exchanger and introduced into the upstream of the two high-temperature heat exchangers. In the upstream high-temperature heat exchanger, heat exchange takes place between the introduced air and the exhaust gas. The air further heated by this heat exchange is discharged from the upstream high-temperature heat exchanger and introduced into the other high-temperature heat exchanger downstream. In the downstream high-temperature heat exchanger, heat exchange takes place between the introduced air and the exhaust gas. The air further heated by this heat exchange is discharged from the downstream high-temperature heat exchanger and introduced into the exhaust gas path at a position downstream of the low-temperature heat exchanger. The heated air introduced into this exhaust gas path raises the temperature of the exhaust gas, preventing the exhaust gas released into the atmosphere from the downstream end of the exhaust gas path from being cooled by the atmosphere and causing the water vapor in the exhaust gas to condense and turn into white smoke. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 52-74133 [Overview of the project] [Problems that the invention aims to solve]

[0006] By the way, in the equipment disclosed in Patent Document 1, in order to ensure a sufficient temperature rise in the air (heat-exchanged gas) obtained by heat exchange with the exhaust gas and to prevent corrosion in each of the two stages of high-temperature heat exchangers, there are significant restrictions on the location of the upstream high-temperature heat exchanger in the exhaust gas path, or the operating conditions of the equipment become stricter regarding the temperature of the exhaust gas discharged from the incinerator.

[0007] Specifically, in the equipment disclosed in Patent Document 1, exhaust gas whose temperature has been reduced by heat exchange in the upstream high-temperature heat exchanger is introduced into the downstream high-temperature heat exchanger of the two high-temperature heat exchangers located upstream of the wet flue gas treatment device. Therefore, the temperature of the air obtained after heat exchange in the downstream high-temperature heat exchanger is inevitably low. Consequently, in the equipment disclosed in Patent Document 1, the temperature of the air obtained by heat recovery from the exhaust gas decreases.

[0008] Furthermore, in the equipment disclosed in Patent Document 1, a wet flue gas treatment device is used in the low-temperature heat exchanger. Air heated by heat exchange with the exhaust gas after wet flue gas treatment is introduced into the upstream high-temperature heat exchanger. However, since the temperature of the exhaust gas is significantly reduced by the wet flue gas treatment, the temperature of the air that has exchanged heat with the treated exhaust gas in the low-temperature heat exchanger rises only slightly. When air at such a temperature is introduced from the low-temperature heat exchanger to the upstream high-temperature heat exchanger and exchanges heat with the exhaust gas in the upstream high-temperature heat exchanger, the surface temperature of the heat transfer section of the high-temperature heat exchanger decreases, and as a result, the high-temperature heat exchanger is more likely to corrode. Specifically, one of the causes of corrosion in heat exchangers is condensation of exhaust gas containing corrosive components. In order to reliably prevent corrosion in the upstream and downstream high-temperature heat exchangers, the temperature of the heat transfer surface of the heat exchanger (surface temperature of the heat transfer section) must be maintained in a temperature range higher than the temperature at which condensation of exhaust gas occurs, even if the temperature drops significantly. Since the temperature of the exhaust gas decreases as it moves downstream along the exhaust gas path, maintaining the surface temperature of the heat transfer section of the upstream and downstream high-temperature heat exchangers above the temperature at which condensation occurs in the exhaust gas imposes strict limitations on the location of the high-temperature heat exchangers along the exhaust gas path. In particular, if multiple heat recovery facilities are installed, the installation location and conditions of such facilities become restricted. Alternatively, even if the temperature of the exhaust gas decreases significantly in the upstream high-temperature heat exchanger as described above, it is necessary to control the temperature of the exhaust gas discharged from the incinerator so that the surface temperature of the heat transfer section remains above the temperature at which condensation occurs in the exhaust gas, which imposes strict operating conditions on the incinerator.

[0009] The object of the present invention is to provide a waste treatment facility and a waste treatment method using the waste treatment facility that can raise the temperature of the heat exchange gas obtained by heat exchange with exhaust gas, prevent corrosion in a high-temperature heat exchanger located in the exhaust gas path, prevent strict restrictions on the location of the upstream high-temperature heat exchanger in the exhaust gas path, and relax the operating conditions of the incinerator. [Means for solving the problem]

[0010] One aspect of the present invention provides a waste treatment facility for processing waste. This waste treatment facility comprises an incinerator for burning waste, an exhaust gas path through which exhaust gas discharged from the incinerator flows, a wet scrubbing device arranged in the exhaust gas path for wet scrubbing treatment of the exhaust gas, a preheat exchanger arranged upstream of the wet scrubbing device on the exhaust gas path for heating the heat exchange gas by exchanging heat between the exhaust gas and the heat exchange gas before the wet scrubbing treatment, and a main heat exchanger arranged upstream of the preheat exchanger on the exhaust gas path for introducing the heat exchange gas heated in the preheat exchanger and further heating the introduced heat exchange gas by heat exchange with the exhaust gas. The main heat exchanger has a main heat exchanger exhaust gas flow path through which the exhaust gas is introduced and flows. The aforementioned preheat exchanger has a preheat exchanger exhaust gas flow path through which the exhaust gas is introduced, and also has a corrosion prevention function that prevents corrosion of the portion of the preheat exchanger that defines the preheat exchanger exhaust gas flow path.

[0011] In this waste treatment facility, heat is recovered from the exhaust gas by passing the heat exchange gas through the heat exchange gas in the order of the main heat exchanger and the preheat exchanger, which is located downstream in the exhaust gas path, followed by the main heat exchanger which is located upstream. Therefore, the outlet temperature of the heat exchange gas after heat exchange in the main heat exchanger can be increased, and the surface temperature of the heat transfer part in the main heat exchanger can be prevented from dropping to the point where condensation of the exhaust gas occurs. By having a corrosion-preventive function that prevents corrosion in the part defining the exhaust gas flow path, corrosion can be prevented in both the main heat exchanger and the preheater. Furthermore, it is possible to avoid strict restrictions on the position of the main heat exchanger on the exhaust gas path in order to maintain the surface temperature of the heat transfer part of the main heat exchanger at a temperature range higher than the temperature at which condensation of the exhaust gas occurs. In addition, the operating conditions of the incinerator required to maintain the surface temperature of the heat transfer part of the main heat exchanger at a temperature range higher than the temperature at which condensation of the exhaust gas occurs can be relaxed.

[0012] Specifically, in the exhaust gas path, the temperature of the exhaust gas decreases as it moves downstream. Therefore, in this waste treatment facility, heat is first recovered from the exhaust gas by exchanging heat with a heat exchange gas in a downstream preheat exchanger. Then, the heat recovered from the heat exchange gas is introduced into the upstream main heat exchanger, where it further exchanges heat with the higher-temperature exhaust gas, thereby recovering even more heat from the exhaust gas and increasing the temperature of the heat exchange gas obtained through heat exchange with the exhaust gas.

[0013] Furthermore, in this waste treatment facility, although the temperature in the preheater is lower than on the upstream side, the exhaust gas, which is still at a relatively high temperature because it has not yet undergone wet scrubbing treatment, exchanges heat with the heat-exchanged gas. The heated heat-exchanged gas is then introduced into the main heat exchanger, where it further exchanges heat with the exhaust gas. This heat exchange in the main heat exchanger prevents the surface temperature of the heat transfer section of the main heat exchanger from dropping to a level where condensation of the exhaust gas occurs. Therefore, if condensation of the exhaust gas occurs in either the main heat exchanger or the preheater, it is limited to the preheater, which is located further downstream and where the temperature of the introduced exhaust gas and the introduced heat-exchanged gas are both lower than on the upstream side. Consequently, only the preheater has a corrosion prevention function to prevent corrosion in the part that defines the exhaust gas flow path of the preheater, and corrosion due to exhaust gas condensation can be prevented in either the main heat exchanger or the preheater.

[0014] Furthermore, since the temperature of the exhaust gas decreases as it moves downstream in the exhaust gas path, even if the temperature of the heat exchange gas introduced into the main heat exchanger is low and the temperature of the heat transfer section of the main heat exchanger decreases, it is necessary to restrict the position of the main heat exchanger to a location in the exhaust gas path such that the surface temperature of the heat transfer section is maintained in a temperature range higher than the temperature at which condensation of the exhaust gas occurs. However, in this waste treatment facility, as described above, the heat exchange gas that has been heated by heat exchange with the exhaust gas, which is maintained at a relatively high temperature before wet scrubbing treatment, in the preheater is introduced into the main heat exchanger, so the surface temperature of the heat transfer section in the main heat exchanger does not decrease to the extent that condensation of the exhaust gas occurs. Therefore, it is possible to prevent the restriction on the position of the main heat exchanger in the exhaust gas path from becoming too strict. In addition, the operating conditions of the incinerator regarding the temperature of the exhaust gas discharged from the incinerator can be relaxed in order to maintain the surface temperature of the heat transfer section in the main heat exchanger in a temperature range higher than the temperature at which condensation of the exhaust gas occurs.

[0015] Preferably, the corrosion prevention function is provided only in the pre-heat exchanger among the main heat exchanger and the pre-heat exchanger. This makes it possible to ensure reliable corrosion prevention by providing the corrosion prevention function to the pre-heat exchanger where the temperature of the flowing exhaust gas is low, while reducing costs by omitting the corrosion prevention function in the main heat exchanger where the temperature of the flowing exhaust gas is high and corrosion is less likely to occur.

[0016] The corrosion prevention function prevents corrosion of the portion of the preheat exchanger that defines the preheat exchanger exhaust gas flow path by using a material in that portion, and it is preferable that the material of that portion is more corrosion-resistant than the material of the portion of the main heat exchanger that defines the main heat exchanger exhaust gas flow path.

[0017] With this configuration, corrosion of the portion of the preheat exchanger that defines the preheat exchanger exhaust gas flow path can be prevented by the simple means of using a highly corrosion-resistant material in that portion of the preheat exchanger.

[0018] The material of the portion of the preheat exchanger that defines the exhaust gas flow path is preferably one of the following: a nickel alloy containing 40% by mass or more nickel, pure titanium, or a titanium alloy containing 50% by mass or more titanium. Examples of nickel alloys include Hastelloy®, ALLOY, and Inconel®, which contain 40% by mass or more nickel as the main component. Alternatively, pure titanium, a titanium alloy containing 50% by mass or more titanium may be selected instead of a nickel alloy, or weathering steel (Corten steel) with protective rust formed on its surface by copper or nickel may be selected.

[0019] Preferably, the waste treatment facility further includes a heated gas path, and the heated gas path connects the main heat exchanger and the downstream end of the exhaust gas path so that the heat exchange gas, which has been heated in the main heat exchanger and passed through the main heat exchanger, is guided to the downstream end of the exhaust gas path and the heat exchange gas is added to the exhaust gas at the downstream end.

[0020] This configuration prevents white smoke from forming when exhaust gas is released into the atmosphere from the downstream end of the exhaust gas path. Specifically, the exhaust gas reaches the downstream end of the exhaust gas path. When the temperature drops and the exhaust gas is released into the atmosphere from the downstream end of the exhaust gas path, it may be further cooled by the atmosphere, causing the water vapor in the exhaust gas to condense and turn into white smoke. In contrast, in this configuration, the heat exchange gas heated in the main heat exchanger is introduced into the downstream end of the exhaust gas path through the heated gas path and added to the exhaust gas. This heated heat exchange gas can raise the temperature of the exhaust gas, thus preventing it from turning into white smoke even when it is cooled by the atmosphere as it is released into the atmosphere from the downstream end of the exhaust gas path.

[0021] Preferably, the waste treatment facility further includes a power generation facility that generates electricity using the thermal energy of the heat-exchanged gas that has been heated in the main heat exchanger and passed through the main heat exchanger.

[0022] This configuration allows for the effective use of recovered thermal energy to generate electricity in a waste treatment facility that can raise the temperature of the heat exchange gas obtained by heat recovery from exhaust gas, as described above. Furthermore, the remaining thermal energy of the heat exchange gas after a portion of the thermal energy has been recovered in the power generation facility can be used to prevent white smoke.

[0023] The waste treatment facility further comprises a dust collector for collecting dust contained in the exhaust gas, and it is preferable that the dust collector is located upstream of the preheater on the exhaust gas path.

[0024] According to this configuration, it is possible to prevent the blockage of the preheating exchanger exhaust gas flow path and the promotion of the occurrence of corrosion in the preheating exchanger due to this blockage. Specifically, if the exhaust gas is introduced into the preheating exchanger exhaust gas flow path in a state containing dust, the dust may accumulate in the preheating exchanger exhaust gas flow path, and there is a risk of blockage in the preheating exchanger exhaust gas flow path. When such a blockage occurs, when condensation of the exhaust gas occurs in the preheating exchanger exhaust gas flow path, the condensate containing the corrosive components is difficult to escape from the preheating exchanger exhaust gas flow path. As a result, corrosion is likely to occur in the preheating exchanger. On the other hand, in this configuration, since the dust contained in the exhaust gas is collected by the dust collector located upstream of the preheating exchanger, the exhaust gas introduced into the preheating exchanger exhaust gas flow path does not contain dust. As a result, it is possible to prevent the blockage of the preheating exchanger exhaust gas flow path as described above. Therefore, it is possible to prevent the occurrence of corrosion in the preheating exchanger due to the blockage of the preheating exchanger exhaust gas flow path. In addition, since the blockage of the preheating exchanger exhaust gas flow path can be prevented as described above, it is possible to narrow the preheating exchanger exhaust gas flow path. As a result, it is also possible to make the preheating exchanger smaller.

[0025] It is preferable that the dust collector is arranged on the downstream side of the main heat exchanger on the exhaust gas path.

[0026] According to this configuration, since the exhaust gas whose temperature has decreased due to heating of the heat exchange gas in the main heat exchanger flows into the dust collector, it is possible to avoid the requirement for high heat resistance for the dust collector.

[0027] It is preferable that the corrosion prevention functional part has a cleaning device for cleaning the inside of the preheating exchanger exhaust gas flow path.

[0028] According to this configuration, the corrosive components in the exhaust gas attached to the inner wall surface of the preheating exchanger exhaust gas flow path can be washed away by the cleaning device, and the occurrence of corrosion in the preheating exchanger can be prevented.

[0029] Preferably, the cleaning device is provided only for the pre-heat exchanger among the main heat exchanger and the pre-heat exchanger. This allows for reliable corrosion prevention through cleaning by the cleaning device in the pre-heat exchanger where the temperature of the flowing exhaust gas is low, while reducing costs by omitting the cleaning device in the main heat exchanger where the temperature of the flowing exhaust gas is high and corrosion is less likely to occur.

[0030] Preferably, the waste treatment facility further comprises a combustion air supply device that supplies combustion air used for burning the waste in the incinerator to the incinerator, and the combustion air supply device is configured to heat the combustion air using the thermal energy of the exhaust gas at a position upstream of the main heat exchanger in the exhaust gas path, and to supply the heated combustion air to the incinerator.

[0031] This configuration reduces the energy consumed separately for heating and supplying combustion air to the incinerator, while also preventing corrosion caused by condensation of exhaust gas in the main heat exchanger. Specifically, if the combustion air used to burn waste in the incinerator is heated using energy unrelated to the thermal energy of the exhaust gas before being supplied to the incinerator, additional energy is consumed. In contrast, in this configuration, the combustion air supply device uses the thermal energy of the exhaust gas to heat the combustion air before supplying it to the incinerator, thus reducing the energy consumed separately. Furthermore, in this configuration, the combustion air supply device heats the combustion air by utilizing the thermal energy of the exhaust gas at a location upstream of the main heat exchanger in the exhaust gas path. As a result, the exhaust gas, whose temperature has been lowered by the use of the thermal energy of the exhaust gas by the combustion air supply device, is introduced into the main heat exchanger. In this case, there is concern that the surface temperature of the heat transfer section of the main heat exchanger may drop to a temperature range where condensation of the exhaust gas occurs. However, as mentioned above, the heat exchange gas introduced into the main heat exchanger is heated to a relatively high temperature by the exhaust gas before wet scrubbing treatment in the preheater. Therefore, the temperature of the exhaust gas that has exchanged heat with this heat exchange gas prevents the surface temperature of the heat transfer section of the main heat exchanger from dropping to a temperature where condensation of the exhaust gas occurs. Consequently, this configuration prevents condensation of the exhaust gas in the main heat exchanger and also prevents corrosion in the main heat exchanger caused by that exhaust gas condensation.

[0032] Another aspect of the present invention is a waste treatment method that uses the waste treatment equipment described above. In this waste treatment method, the waste is incinerated in the incinerator, and the exhaust gas generated by the incineration flows through the exhaust gas path and, before being subjected to wet scrubbing treatment by the wet scrubbing device, is heated by heat exchange with a heat exchange gas in the preheat exchanger, and the heat exchange gas heated in the preheat exchanger is introduced into the main heat exchanger and further heated by heat exchange with the exhaust gas in the main heat exchanger.

[0033] According to this waste treatment method, for the same reasons as those explained for the waste treatment equipment, the temperature of the heat exchange gas obtained by heat exchange with the exhaust gas can be increased while preventing corrosion in both the main heat exchanger and the auxiliary heat exchanger located in the exhaust gas path, preventing stricter restrictions on the location of the main heat exchanger in the exhaust gas path, and relaxing the operating conditions of the incinerator.

[0034] Preferably, the incinerator burns waste containing ammonia components, and the incineration of said waste generates exhaust gas containing ammonia components. The ammonia contained in the exhaust gas reacts with the acid also contained in the exhaust gas to suppress corrosion in the preheat exchanger, where the exhaust gas temperature is low and the acid is likely to be generated. This makes it possible to simplify the corrosion prevention function (for example, by reducing the amount of corrosion-resistant material used in the preheat exchanger) and reduce costs. [Effects of the Invention]

[0035] As described above, the present invention provides a waste treatment facility and a waste treatment method using the waste treatment facility that can raise the temperature of the heat exchange gas obtained by heat exchange with exhaust gas, prevent corrosion in the main heat exchanger and auxiliary heat exchanger located in the exhaust gas path, prevent strict restrictions on the position of the upstream main heat exchanger in the exhaust gas path, and relax the operating conditions of the incinerator. [Brief explanation of the drawing]

[0036] [Figure 1] This diagram schematically shows a waste treatment facility according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of a white smoke prevention preheat exchanger and cleaning device for a waste treatment facility according to one embodiment of the present invention. [Figure 3] Figure 2 shows a partial cross-sectional view of the preheater body of the white smoke prevention preheater. [Figure 4]This diagram schematically shows a waste treatment facility based on a comparative example. [Modes for carrying out the invention]

[0037] The following describes in detail a waste treatment facility 1 according to one embodiment of the present invention, based on the drawings.

[0038] Figure 1 schematically shows the waste treatment facility 1 according to this embodiment. The waste treatment facility 1 according to this embodiment comprises an incinerator 2, an exhaust gas path 4, a combustion air supply device 6, a white smoke prevention main heat exchanger 8, a dust collector 10, a white smoke prevention pre-heat exchanger 12, a wet smoke scrubbing device 14, a power generation facility 16, a blower 18, and a white smoke prevention air path 20. The white smoke prevention main heat exchanger 8 is an example of a "main heat exchanger," and the white smoke prevention pre-heat exchanger 12 is an example of a "pre-heat exchanger." The incinerator 2, the combustion air supply device 6, the white smoke prevention main heat exchanger 8, the dust collector 10, the white smoke prevention pre-heat exchanger 12, and the wet smoke scrubbing device 14 are arranged in this order from the upstream side in the direction of exhaust gas flow in the exhaust gas path 4. Hereinafter, the upstream side in the direction of exhaust gas flow in the exhaust gas path 4 will be simply referred to as the upstream side, and the downstream side in the same flow direction will be simply referred to as the downstream side.

[0039] Incinerator 2 incinerates waste such as dewatered sludge. The incinerator 2 in this embodiment is a fluidized bed incinerator, but is not limited to this. Incinerator 2, exhaust gas is generated as waste is incinerated. This exhaust gas contains, for example, chlorine compounds such as hydrogen chloride and corrosive components such as sulfur oxides. Incinerator 2 has an air inlet 2a into which combustion air used for burning waste in the incinerator 2 is introduced, and an exhaust gas outlet 2b for discharging the exhaust gas generated in the incinerator 2.

[0040] The exhaust gas path 4 is the path through which the exhaust gas discharged from the incinerator 2 flows, and is connected to the exhaust gas outlet 2b of the incinerator 2. The exhaust gas path 4 has a first path section 21, a second path section 22, a third path section 23, a fourth path section 24, a fifth path section 25, and a sixth path section 26.

[0041] The first path section 21 connects the exhaust gas outlet 2b of the incinerator 2 to the exhaust gas inlet 28a of the combustion air heat exchanger 28, which will be described later, of the combustion air supply device 6, so as to guide the exhaust gas discharged from the exhaust gas outlet 2b of the combustion air heat exchanger 28, which will be described later, to the exhaust gas inlet 8a of the white smoke prevention main heat exchanger 8, so as to guide the exhaust gas discharged from the exhaust gas outlet 28b of the combustion air heat exchanger 28, which will be described later, to the exhaust gas inlet 8a of the white smoke prevention main heat exchanger 8, so as to guide the exhaust gas discharged from the exhaust gas outlet 8b of the white smoke prevention main heat exchanger 8 to the exhaust gas inlet 10a of the dust collector 10, so as to guide the exhaust gas discharged from the exhaust gas outlet 8b of the dust collector 10, so as to guide the exhaust gas inlet 10a of the dust collector 10. The fourth path section 24 connects the exhaust gas outlet 10b of the dust collector 10 to the exhaust gas inlet 12a of the white smoke prevention pre-heat exchanger 12 so as to guide the exhaust gas from the exhaust gas outlet 10b of the dust collector 10 to the exhaust gas inlet 12a of the white smoke prevention pre-heat exchanger 12. The fifth path section 25 connects the exhaust gas outlet 12b of the white smoke prevention pre-heat exchanger 12 to the exhaust gas inlet 14a of the wet-type fume scrubbing device 14 so as to guide the exhaust gas from the exhaust gas outlet 12b of the wet-type fume scrubbing device 14 to the exhaust gas inlet 14a of the wet-type fume scrubbing device 14. The sixth path section 26 is connected to the exhaust gas outlet 14b of the wet-type fume scrubbing device 14 and is the section through which the exhaust gas discharged from the exhaust gas outlet 14b flows. The exhaust gas is released into the atmosphere from the downstream end of this sixth path section 26, that is, from the downstream end of the exhaust gas path 4. The downstream end of this sixth path section 26 has, for example, a chimney for releasing the exhaust gas into the atmosphere, although it is not shown in the figure.

[0042] The combustion air supply device 6 is a device that heats the combustion air used for burning waste in the incinerator 2 using the thermal energy of the exhaust gas and supplies the heated combustion air to the incinerator 2. The combustion air supply device 6 includes a combustion air heat exchanger 28, a supercharger 30, and a combustion air path 32.

[0043] The combustion air heat exchanger 28 heats the combustion air with the heat from the exhaust gas discharged from the exhaust gas outlet 2b of the incinerator 2 by exchanging heat between the exhaust gas and the combustion air. The combustion air heat exchanger 28 is located downstream of the incinerator 2 on the exhaust gas path 4. The combustion air heat exchanger 28 has an exhaust gas inlet 28a, an exhaust gas outlet 28b, an air inlet 28c, and an air outlet 28d.

[0044] The exhaust gas inlet 28a receives the exhaust gas discharged from the exhaust gas outlet 2b of the incinerator 2 through the first path. This is the point where the air is introduced through section 21 and is connected to the downstream end of the first path section 21. The exhaust gas outlet 28b is the point where exhaust gas is discharged after heat exchange with combustion air in the combustion air heat exchanger 28. The air inlet 28c is the point where combustion air discharged from the compressor 34 of the supercharger 30 (described later) is introduced. The air outlet 28d is the point where combustion air heated by heat exchange with exhaust gas in the combustion air heat exchanger 28 is discharged.

[0045] The supercharger 30 compresses the combustion air and sends the compressed combustion air to the combustion air heat exchanger 28. The supercharger 30 includes a compressor 34 and a turbine 36.

[0046] The compressor 34 compresses the combustion air and discharges the compressed combustion air toward the air inlet 28c of the combustion air heat exchanger 28. The compressor 34 has a compressor inlet 34a, which is the intake port for the combustion air, and a compressor outlet 34b, which is the discharge port for the compressed combustion air.

[0047] The turbine 36 is driven by the pressure and thermal energy of combustion air, which is compressed by the compressor 34 and heated in the combustion air heat exchanger 28. The turbine 36 has a rotating body (not shown) that is rotated by the pressure and thermal energy of the introduced combustion air, and this rotating body is connected to the compressor 34 so that the rotational motion of the rotating body is transmitted to the compressor 34. The compressor 34 is driven by the rotational motion transmitted from the rotating body of the turbine 36 and compresses the combustion air as described above. The turbine 36 has a turbine inlet 36a, which is the intake port for combustion air, and a turbine outlet 36b, which is the exhaust port for the combustion air after the turbine 36 has been driven.

[0048] The combustion air path 32 is the path through which combustion air supplied to the incinerator 2 flows. The compressor 34, the combustion air heat exchanger 28, the turbine 36, and the incinerator 2 are connected so that the combustion air passes through the compressor 34, the combustion air heat exchanger 28, and the turbine 36 in that order before reaching the incinerator 2. The combustion air path 32 has an introduction path section 37, a first intermediate path section 38, a second intermediate path section 40, and a supply path section 42.

[0049] The intake path section 37 is the section that introduces combustion air to the compressor 34 and is connected to the compressor inlet 34a. In Figure 1, the upstream end of the intake path section 37 is open to the atmosphere, and air is drawn into the intake path section 37 as the compressor 34 rotates. However, the configuration is not limited to this, and for example, a blower or other ventilation device may be connected to the upstream end of the intake path section 37 to forcibly supply air. In this case, the intake path section 37 guides the combustion air sent out by the ventilation device to the compressor inlet 34a.

[0050] The first intermediate path section 38 is the section that guides the compressed combustion air discharged from the compressor 34 to the combustion air heat exchanger 28, and connects the compressor outlet 34b to the air inlet 28c of the combustion air heat exchanger 28.

[0051] The second intermediate path section 40 is the part that guides the combustion air, which is heated in the combustion air heat exchanger 28 and discharged from the combustion air heat exchanger 28, to the turbine 36, and connects the air outlet 28d of the combustion air heat exchanger 28 to the turbine inlet 36a.

[0052] The supply path section 42 is the part that guides the combustion air discharged from the turbine 36 to the incinerator 2, and connects the turbine outlet 36b to the air inlet 2a of the incinerator 2.

[0053] The white smoke prevention main heat exchanger 8 and the white smoke prevention auxiliary heat exchanger 12 each exchange heat between the exhaust gas and the white smoke prevention air, thereby heating the white smoke prevention air with the heat of the exhaust gas. The white smoke prevention air is released into the atmosphere from the downstream end of the exhaust gas path 4 (the downstream end of the sixth path section 26). To prevent the exhaust gas from becoming white smoke due to its low temperature, a substance is added to the exhaust gas at the downstream end of the exhaust gas path 4 to raise its temperature. Specifically, at the downstream end of the exhaust gas path 4, white smoke prevention air, which has a higher temperature than the exhaust gas at the downstream end of the exhaust gas path 4 due to being heated in the white smoke prevention preheat exchanger 12 and the white smoke prevention main heat exchanger 8, is introduced through the white smoke prevention air path 20 as described later. The white smoke prevention main heat exchanger 8 is an example of a main heat exchanger in this invention, and the white smoke prevention preheat exchanger 12 is an example of a preheat exchanger in this invention. The white smoke prevention air is an example of a heat exchange gas in this invention.

[0054] Of the white smoke prevention main heat exchanger 8 and the white smoke prevention pre-heat exchanger 12, the white smoke prevention pre-heat exchanger 12 is located further downstream on the exhaust gas path 4, and the white smoke prevention pre-heat exchanger 12 is located upstream of the wet-type smoke scrubbing device 14. Exhaust gas at a lower temperature than the exhaust gas introduced into the white smoke prevention main heat exchanger 8 is introduced into the white smoke prevention pre-heat exchanger 12. Furthermore, as will be described later, the white smoke prevention pre-heat exchanger 12 is located upstream of the white smoke prevention main heat exchanger 8 in the direction of the white smoke prevention airflow in the white smoke prevention air path 20.

[0055] The white smoke prevention preheat exchanger 12 has an exhaust gas inlet 12a, an exhaust gas outlet 12b, an air inlet 12c, and an air outlet 12d. The exhaust gas inlet 12a is where the exhaust gas is introduced and is connected to the downstream end of the fourth path section 24 of the exhaust gas path 4. The exhaust gas outlet 12b is where the exhaust gas that has exchanged heat with the white smoke prevention air in the white smoke prevention preheat exchanger 12 is discharged and is connected to the upstream end of the fifth path section 25 of the exhaust gas path 4. The air inlet 12c is where the white smoke prevention air is introduced. The air outlet 12d is where the white smoke prevention air that has been heated by heat exchange with the exhaust gas in the white smoke prevention preheat exchanger 12 is discharged.

[0056] The white smoke prevention preheat exchanger 12 has multiple preheat exchanger exhaust gas passages 47 and multiple preheat exchanger air passages 48 inside. In Figure 1, the preheat exchanger exhaust gas passages 47 and preheat exchanger air passages 48 are schematically represented, but in reality, multiple preheat exchanger exhaust gas passages 47 and multiple preheat exchanger air passages 48 are arranged in parallel inside the white smoke prevention preheat exchanger 12. The preheat exchanger exhaust gas passages 47 are passages through which exhaust gas is introduced and flows, and the preheat exchanger air passages 48 are passages through which white smoke prevention air is introduced and flows. The upstream end of each preheat exchanger exhaust gas passage 47 is connected to the exhaust gas inlet 12a, and the downstream end of each preheat exchanger exhaust gas passage 47 is connected to the exhaust gas outlet 12b. The upstream end of each preheater air passage 48 is connected to the air inlet 12c, and the downstream end of each preheater air passage 48 is connected to the air outlet 12d.

[0057] It is preferable to install the white smoke prevention main heat exchanger 8 and the white smoke prevention auxiliary heat exchanger 12 such that the amount of heat recovered by the white smoke prevention main heat exchanger 8 is 1 to 5 times the amount of heat recovered by the white smoke prevention auxiliary heat exchanger 12. By making the amount of heat recovered by the white smoke prevention main heat exchanger 8 equal to or greater than the amount of heat recovered by the white smoke prevention auxiliary heat exchanger 12, it is possible to maximize the total amount of heat recovered by the white smoke prevention main heat exchanger 8 and the white smoke prevention auxiliary heat exchanger 12 while suppressing the size of the white smoke prevention auxiliary heat exchanger 12.

[0058] As shown in Figure 3, the white smoke prevention preheat exchanger 12 comprises a preheat exchanger body 13, which is a so-called plate heat exchanger having a plurality of first plates 49 and a plurality of second plates 50. Figure 3 partially shows a cross-section of the preheat exchanger body 13 in the direction along the thickness direction of the first plates 49 and second plates 50. The first plates 49 and second plates 50 are alternately stacked and joined to each other. A plurality of grooves are formed on the surface of each first plate 49, and the openings of these grooves are sealed by the second plates 50 joined to the surface of the plate, thereby forming a plurality of preheat exchanger exhaust gas passages 47. In addition, a plurality of grooves are formed on the surface of each second plate 50, and the openings of these grooves are sealed by the first plates joined to the surface of the plate. Multiple preheat exchanger air passages 48 are formed by sealing with plate 49. The exhaust gas flowing through the preheat exchanger exhaust gas passage 47 and the white smoke prevention air flowing through the preheat exchanger air passage 48 exchange heat via the first plate 49 or the second plate 50 between the preheat exchanger exhaust gas passage 47 and the preheat exchanger air passage 48.

[0059] The white smoke prevention preheater 12 has a corrosion prevention function section 15 that prevents corrosion of the first plate 49 and the second plate 50, which are parts of the preheater body 13 that define the preheater exhaust gas flow path 47. In this embodiment, the corrosion prevention function section 15 prevents corrosion of the first plate 49 and the second plate 50 by the material of the first plate 49 and the second plate 50. In other words, the first plate 49 and the second plate 50 themselves constitute the corrosion prevention function section 15 that prevents their corrosion. Specifically, these first plate 49 and the second plate 50 are made of a material with higher corrosion resistance than the part that defines the main heat exchanger exhaust gas flow path 51 described later in the white smoke prevention main heat exchanger 8. More specifically, the material of the first plate 49 and the second plate 50 is, for example, a nickel alloy containing 40% by mass or more nickel, pure titanium, or a titanium alloy containing 50% by mass or more titanium. The nickel alloy may, for example, be a Ni-Cr-Fe nickel alloy containing 30-76 mass% Ni, 12-23 mass% Cr, and 2-46 mass% Fe. Alternatively, the nickel alloy may be a Ni-Cr-Mo nickel-molybdenum alloy containing 40-71 mass% Ni, 1-30 mass% Cr, and 8-30 mass% Mo. Furthermore, examples of the nickel alloy include Hastelloy®, ALLOY, and Inconel®. Examples of Hastelloy include Hastelloy C-22 (3 mass% iron, 56 mass% nickel, 22 mass% chromium, 13 mass% molybdenum, 3 mass% tungsten), Hastelloy C-276 (5 mass% iron, 57 mass% nickel, 16 mass% chromium, 16 mass% molybdenum, 4 mass% tungsten), and other Hastelloy products.Other Hastelloy products include Hastelloy containing 43-71% by mass of nickel, such as Hastelloy C-4 (65% nickel, 16% chromium, 16% molybdenum), Hastelloy C-22HS (61% nickel, 21% chromium, 17% molybdenum), Hastelloy C-2000 (59% nickel, 23% chromium, 16% molybdenum, 1.6% copper), and Hastelloy HYBRID-BC1 (62% nickel, 15% chromium, 22% molybdenum, 0.25% manganese).

[0060] Examples of alloys include ALLOY22 (2-6% iron, approximately 56% nickel, 20-22.5% chromium, 12.5-14.5% molybdenum, 2.5-3.5% tungsten) and ALLOY C-276 (4-7% iron, approximately 57% nickel, 14.5-16.5% chromium, 15-17% molybdenum, 3-4.5% tungsten).

[0061] Examples of Inconel include Inconel 600 (6-10% iron, 72% nickel, 14-17% chromium), Inconel 625 (58% nickel, 20-23% chromium, 8-10% molybdenum, 3.15-4.15% niobium), and Inconel 718 (small amount of iron, 50-55% nickel, 17-21% chromium, 2.8-3.3% molybdenum, 4.75-5.5% niobium, 0.65-1.15% titanium, 0.2-0.8% aluminum).

[0062] Alternatively, pure titanium or a titanium alloy containing 50% or more by mass of titanium may be selected instead of nickel alloy, or weathering steel (Corten steel) with a protective rust formed on its surface using copper or nickel may be selected.

[0063] Furthermore, in this embodiment, the corrosion prevention function unit 15 includes a cleaning device 19 (see Figure 2). The cleaning device 19 cleans the inside of the preheat exchanger exhaust gas passage 47 and is attached to the preheat exchanger body 13. The cleaning device 19 is configured to clean the inside of each preheat exchanger exhaust gas passage 47 by passing water through it. The cleaning device 19 may be configured to automatically pass water through each preheat exchanger exhaust gas passage 47 at regular intervals, or it may be configured to pass water through each preheat exchanger exhaust gas passage 47 in response to operation by an operator. Corrosive components are washed away by cleaning with the cleaning device 19.

[0064] The main heat exchanger 8 for preventing white smoke is supplied with white smoke prevention air that has been heated by heat exchange with the exhaust gas in the pre-heat exchanger 12 for preventing white smoke. The main heat exchanger 8 is located upstream of the pre-heat exchanger 12 in the exhaust gas path 4, and the exhaust gas supplied to the main heat exchanger 8 is at a higher temperature than the exhaust gas supplied to the pre-heat exchanger 12.

[0065] The white smoke prevention main heat exchanger 8 has an exhaust gas inlet 8a, an exhaust gas outlet 8b, an air inlet 8c, and an air outlet 8d. The exhaust gas inlet 8a is where the exhaust gas is introduced and is connected to the downstream end of the second path section 22 of the exhaust gas path 4. The exhaust gas outlet 8b is where the exhaust gas that has exchanged heat with the white smoke prevention air in the white smoke prevention main heat exchanger 8 is discharged and is connected to the upstream end of the third path section 23 of the exhaust gas path 4. The air inlet 8c is where the white smoke prevention air that has been heated in the white smoke prevention preheating heat exchanger 12 and discharged from the white smoke prevention preheating heat exchanger 12 is introduced. The air outlet 8d is where the white smoke prevention air that has been heated by exchanging heat with the exhaust gas in the white smoke prevention main heat exchanger 8 is discharged.

[0066] The white smoke prevention main heat exchanger 8 has a main heat exchanger exhaust gas passage 51 and a main heat exchanger air passage 52 inside. Figure 1 schematically shows the main heat exchanger exhaust gas passage 51 and the main heat exchanger air passage 52 of the white smoke prevention main heat exchanger 8. The structure of the white smoke prevention main heat exchanger 8, and the structure and arrangement of the main heat exchanger exhaust gas passage 51 and the main heat exchanger air passage 52 inside it, are the same as those of various conventionally known heat exchangers and their internal passages. A multi-tube heat exchanger or a plate heat exchanger can be used as the white smoke prevention main heat exchanger 8. From the viewpoint of preventing blockage of the exhaust gas passage in heat exchange of exhaust gas containing dust, a multi-tube heat exchanger can be used as the white smoke prevention main heat exchanger 8. It is desirable to use a type heat exchanger. The main heat exchanger exhaust gas passage 51 is the passage through which exhaust gas is introduced and flows, and the main heat exchanger air passage 52 is the passage through which white smoke prevention air is introduced and flows. The upstream end of the main heat exchanger exhaust gas passage 51 is connected to the exhaust gas inlet 8a, and the downstream end of the main heat exchanger exhaust gas passage 51 is connected to the exhaust gas outlet 8b. The upstream end of the main heat exchanger air passage 52 is connected to the air inlet 8c, and the downstream end of the main heat exchanger air passage 52 is connected to the air outlet 8d.

[0067] The white smoke prevention air supplied to the white smoke prevention pre-heat exchanger 12 and the white smoke prevention main heat exchanger 8 is blown by a blower 18. The blower 18 is connected to the upstream end of the white smoke prevention air path 20.

[0068] The white smoke prevention air path 20 is a path through which white smoke prevention air flows. This white smoke prevention air path 20 has a first air path section 53, a second air path section 54, a third air path section 56, and a fourth air path section 58. The first air path section 53 connects the blower 18 and the air inlet 12c of the white smoke prevention pre-heat exchanger 12 so as to guide the white smoke prevention air sent from the blower 18 to the white smoke prevention pre-heat exchanger 12. The second air path section 54 connects the air outlet 12d of the white smoke prevention pre-heat exchanger 12 and the air inlet 8c so as to guide the white smoke prevention air discharged from the air outlet 12d of the white smoke prevention pre-heat exchanger 12 to the air inlet 8c of the white smoke prevention main heat exchanger 8. The third air path section 56 connects the air outlet 8d of the white smoke prevention main heat exchanger 8 to the air inlet 62a of the hot water boiler 62 of the power generation equipment 16, which will be described later, so as to guide the white smoke prevention air discharged from the air outlet 8d of the white smoke prevention main heat exchanger 8 to the air inlet 62a of the hot water boiler 62 of the power generation equipment 16, which will be described later, to the downstream end of the exhaust gas path 4 (the downstream end of the sixth path section 26). The third air path section 56 and the fourth air path section 58 are examples of heated gas paths in the present invention, in which white smoke prevention air that has been heated in the white smoke prevention main heat exchanger 8 and passed through the white smoke prevention main heat exchanger 8 is guided to the downstream side of the exhaust gas path 4, and the white smoke prevention air is added to the exhaust gas at the downstream end.

[0069] As described above, the white smoke prevention air sent from the blower 18 passes through the white smoke prevention air path 20, then through the white smoke prevention pre-heat exchanger 12, the white smoke prevention main heat exchanger 8, and the hot water boiler 62 of the power generation equipment 16 in that order, before being introduced to the downstream end of the exhaust gas path 4.

[0070] The dust collector 10 is positioned upstream of the white smoke prevention preheating heat exchanger 12 on the exhaust gas path 4 and is a device that removes dust from the exhaust gas by capturing dust such as soot contained in the exhaust gas. In this embodiment, the dust collector 10 is located upstream of the white smoke prevention preheating heat exchanger 12 and downstream of the white smoke prevention main heat exchanger 8 on the exhaust gas path 4. That is, the dust collector 10 removes dust from the exhaust gas after heat exchange in the white smoke prevention main heat exchanger 8, before it is introduced into the white smoke prevention preheating heat exchanger 12. Therefore, the exhaust gas that has had dust removed by the dust collector 10 is introduced into the white smoke prevention preheating heat exchanger 12.

[0071] In this embodiment, the dust collector 10 is a so-called bag filter. A bag filter has a filter cloth and removes dust from the exhaust gas by capturing dust contained in the exhaust gas with the filter cloth as the exhaust gas passes through the cloth. The dust collector 10 has an exhaust gas inlet 10a, which is the point where the exhaust gas is introduced, and an exhaust gas outlet 10b, which is the point where the exhaust gas is discharged after the dust has been removed in the dust collector 10. The exhaust gas inlet 10a is connected to the downstream end of the third path portion 23 of the exhaust gas path 4. The exhaust gas outlet 10b is connected to the upstream end of the fourth path portion 24 of the exhaust gas path 4.

[0072] The wet scrub device 14 is a device that performs wet scrub treatment on exhaust gas, and on the exhaust gas path 4 It is located downstream of the white smoke prevention preheat exchanger 12. This wet fume scrubbing device 14 has a tower-shaped housing, and by spraying a cleaning solution such as water into the housing and bringing the sprayed cleaning solution into contact with the exhaust gas introduced into the housing from the bottom of the housing, harmful components such as chlorine compounds such as hydrogen chloride and sulfur oxides contained in the exhaust gas are dissolved into the cleaning solution and harmful components are removed from the exhaust gas through a wet fume scrubbing treatment. Since the temperature of the cleaning solution is lower than the temperature of the exhaust gas introduced into the wet fume scrubbing device 14, the temperature of the exhaust gas that has undergone wet fume scrubbing treatment is lower than the temperature of the exhaust gas before wet fume scrubbing treatment introduced into the wet fume scrubbing device 14.

[0073] The wet fume scrubbing device 14 has an exhaust gas inlet 14a into which exhaust gas is introduced, and an exhaust gas outlet 14b into which the exhaust gas that has been treated with wet fume scrubbing in the wet fume scrubbing device 14 is discharged. The exhaust gas inlet 14a is connected to the downstream end of the fifth path section 25 of the exhaust gas path 4. The exhaust gas outlet 14b is connected to the upstream end of the sixth path section 26 of the exhaust gas path 4.

[0074] The power generation equipment 16 is a device that generates electricity using the thermal energy of the smoke-preventing air that has been heated in the smoke-preventing main heat exchanger 8. In other words, smoke-preventing air that has been heated in the smoke-preventing main heat exchanger 8 and passed through the smoke-preventing main heat exchanger 8 is introduced into the power generation equipment 16, and the power generation equipment 16 is configured to generate electricity using the thermal energy of the introduced smoke-preventing air. This power generation equipment 16 includes a hot water boiler 62, a power generation device 64, and a circulation circuit 66.

[0075] The hot water boiler 62 heats water and produces hot water by utilizing the thermal energy of the smoke-preventing air that has been heated in the smoke-preventing main heat exchanger 8 and passed through the smoke-preventing main heat exchanger 8. The hot water boiler 62 is located downstream of the smoke-preventing main heat exchanger 8 in the direction of the smoke-preventing air flow on the smoke-preventing air path 20. The hot water boiler 62 has an air inlet 62a into which the smoke-preventing air is introduced, and an air outlet 62b into which the smoke-preventing air is discharged after heating the water in the hot water boiler 62. The air inlet 62a is connected to the downstream end of the third air path section 56. The air outlet 62b is connected to the upstream end of the fourth air path section 58.

[0076] The power generation device 64 generates electricity using hot water produced by the hot water boiler 62 as a heat source. The power generation device 64 is connected to the hot water boiler 62 by a circulation circuit 66. Hot water produced by the hot water boiler 62 is introduced into the power generation device 64 through this circulation circuit 66, and after being used for power generation in the power generation device 64, the hot water discharged from the power generation device 64 is returned to the hot water boiler 62.

[0077] In this embodiment, the power generation device 64 is a so-called binary power generation device. Specifically, although not shown in the figures, the power generation device 64 includes a circulation circuit through which a working medium, which is a low-boiling-point refrigerant, circulates, an evaporator, an expander, a condenser, and a working medium pump arranged in the circulation circuit, and a generator connected to the expander. Hot water introduced from the hot water boiler 62 to the power generation device 64 is introduced into the evaporator. The working medium pump circulates the working medium in the circulation circuit, and in the evaporator, heat exchange takes place between the introduced hot water and the working medium, causing the working medium to evaporate and generate steam. This steam is introduced into the expander, which rotates the expander. This rotational motion of the expander is transmitted to the generator connected to the expander, which then operates and generates electricity. The steam of the working medium discharged from the expander is introduced into the condenser, where it condenses into a liquid, and this liquid working medium is returned to the evaporator. Furthermore, the type of expander used in a binary power generation system is not limited; for example, radial turbines, screw turbines, or other types may be employed.

[0078] Next, a waste treatment method using the waste treatment equipment 1 according to this embodiment will be described.

[0079] In the waste treatment method according to this embodiment, waste is incinerated in an incinerator 2, and the exhaust gas generated by the incineration of the waste is discharged from the exhaust gas outlet 2b of the incinerator 2 to the first path section 21 of the exhaust gas path 4. This discharged exhaust gas is then introduced from the first path section 21 to the combustion air heat exchanger 28 of the combustion air supply device 6.

[0080] Furthermore, combustion air is introduced into the combustion air heat exchanger 28 through the combustion air path 32. In the combustion air heat exchanger 28, heat exchange takes place between the introduced exhaust gas and the combustion air, and the resultingly heated combustion air exits the combustion air heat exchanger 28 and is introduced into the turbine 36. The combustion air introduced into the turbine 36 drives the turbine 36, and the compressor 34 operates in conjunction with the driving of the turbine 36. As a result, the compressor 34 compresses the combustion air, and the compressed combustion air is sent from the compressor outlet 34b through the first intermediate path section 38 of the combustion air path 32 to the combustion air heat exchanger 28. In the combustion air heat exchanger 28, heat exchange takes place between the introduced compressed combustion air and the exhaust gas, and the compressed combustion air is heated by the heat of the exhaust gas. This heated, compressed combustion air, i.e., heated and pressurized combustion air, is introduced from the combustion air heat exchanger 28 to the turbine 36 to drive the turbine 36, and then from the turbine 36 through the supply path section 42 of the combustion air path 32 to the incinerator 2. In the incinerator 2, the introduced combustion air is used to burn the waste.

[0081] Heat exchange between the exhaust gas and the combustion air in the combustion air heat exchanger 28 lowers the temperature of the exhaust gas, and the exhaust gas after heat exchange is discharged from the exhaust gas outlet 28b of the combustion air heat exchanger 28 to the second path section 22 of the exhaust gas path 4. The temperature of the exhaust gas at the exhaust gas outlet 28b of the combustion air heat exchanger 28 is, for example, 400°C to 650°C. The exhaust gas discharged to the second path section 22 is guided through the second path section 22 to the exhaust gas inlet 8a of the white smoke prevention main heat exchanger 8, and from the exhaust gas inlet 8a it is introduced into the main heat exchanger exhaust gas flow path 51. The temperature of the exhaust gas at the exhaust gas inlet 8a of the white smoke prevention main heat exchanger 8 is similar to the temperature of the exhaust gas at the exhaust gas outlet 28b of the combustion air heat exchanger 28, for example, 400°C to 650°C.

[0082] In the white smoke prevention main heat exchanger 8, heat exchange takes place between the white smoke prevention air flowing through the main heat exchanger air passage 52 and the exhaust gas flowing through the main heat exchanger exhaust gas passage 51, as described later. This heat exchange in the white smoke prevention main heat exchanger 8 lowers the temperature of the exhaust gas. After heat exchange with the white smoke prevention air in the white smoke prevention main heat exchanger 8, the exhaust gas is discharged from the downstream end of the main heat exchanger exhaust gas passage 51 through the exhaust gas outlet 8b to the third path section 23 of the exhaust gas path 4. The temperature of the exhaust gas at the exhaust gas outlet 8b of the white smoke prevention main heat exchanger 8 is, for example, 180°C to 300°C, more preferably 200°C to 250°C.

[0083] The exhaust gas discharged from the exhaust gas outlet 8b of the white smoke prevention main heat exchanger 8 to the third path section 23 is introduced to the dust collector 10 through the third path section 23. In the dust collector 10, dust is removed from the introduced exhaust gas. The dust-free exhaust gas is discharged from the exhaust gas outlet 10b of the dust collector 10 to the fourth path section 24 of the exhaust gas path 4.

[0084] The exhaust gas discharged from the exhaust gas outlet 10b of the dust collector 10 to the fourth path section 24 is guided through the fourth path section 24 to the exhaust gas inlet 12a of the white smoke prevention pre-heat exchanger 12, and from the exhaust gas inlet 12a it is introduced into the exhaust gas flow paths 47 of each pre-heat exchanger. The temperature of the exhaust gas at the exhaust gas inlet 12a of the white smoke prevention pre-heat exchanger 12, in other words, the temperature of the exhaust gas at the upstream end of the exhaust gas flow path 47 of each pre-heat exchanger is similar to the temperature of the exhaust gas at the exhaust gas outlet 8b of the white smoke prevention main heat exchanger 8, for example, 180°C to 300°C, more preferably 200°C to 250°C.

[0085] In the white smoke prevention preheat exchanger 12, heat exchange takes place between the white smoke prevention air flowing through each preheat exchanger air passage 48 and the exhaust gas flowing through each preheat exchanger exhaust gas passage 47, as described later. This heat exchange in the white smoke prevention preheat exchanger 12 lowers the temperature of the exhaust gas. After heat exchange with the white smoke prevention air in the white smoke prevention preheat exchanger 12, the exhaust gas is discharged from the downstream end of each preheat exchanger exhaust gas passage 47 through the exhaust gas outlet 12b to the fifth passage section 25 of the exhaust gas path 4. The temperature of the exhaust gas at the exhaust gas outlet 12b of the white smoke prevention preheat exchanger 12 is, for example, 50°C to 150°C, more preferably 80°C to 120°C.

[0086] The exhaust gas discharged from the exhaust gas outlet 12b of the white smoke prevention preheat exchanger 12 to the fifth path section 25 is guided through the fifth path section 25 to the exhaust gas inlet 14a of the wet scrubbing device 14, and introduced into the wet scrubbing device 14 from the exhaust gas inlet 14a. The temperature of the exhaust gas at the exhaust gas inlet 14a of the wet scrubbing device 14 is similar to the temperature of the exhaust gas at the exhaust gas outlet 12b of the white smoke prevention preheat exchanger 12, for example, 50°C to 150°C, more preferably 80°C to 120°C.

[0087] In the wet fume scrub device 14, the exhaust gas is subjected to wet fume scrub treatment, removing harmful components contained in the exhaust gas. This wet fume scrub treatment lowers the temperature of the exhaust gas. After the wet fume scrub treatment, the exhaust gas is discharged from the exhaust gas outlet 14b of the wet fume scrub device 14 to the sixth path section 26 of the exhaust gas path 4. The temperature of the exhaust gas at the exhaust gas outlet 14b of the wet fume scrub device 14 after the wet fume scrub treatment is, for example, 30°C to 70°C, more preferably 30°C to 50°C. The exhaust gas discharged to the sixth path section 26 is released into the atmosphere from the downstream end of the sixth path section 26.

[0088] Meanwhile, the smoke-preventing air sent from the blower 18 is guided through the first air path section 53 to the air inlet 12c of the smoke-preventing preheat exchanger 12, and from there it is introduced into the air passages 48 of each preheat exchanger. The temperature of the smoke-preventing air at the air inlet 12c of the smoke-preventing preheat exchanger 12, in other words, the temperature of the smoke-preventing air at the upstream end of each preheat exchanger air passage 48, is, for example, the same as the ambient temperature, which is 20°C to 30°C.

[0089] In the white smoke prevention preheat exchanger 12, heat exchange takes place between the white smoke prevention air flowing through each preheat exchanger air passage 48 and the exhaust gas flowing through each preheat exchanger exhaust gas passage 47, and the white smoke prevention air is heated by the heat of the exhaust gas. The white smoke prevention air heated in the white smoke prevention preheat exchanger 12 is discharged from the downstream end of each preheat exchanger air passage 48 through the air outlet 12d to the second air passage section 54. The temperature of the white smoke prevention air at the air outlet 12d of the white smoke prevention preheat exchanger 12, in other words, the temperature of the white smoke prevention air at the downstream end of each preheat exchanger air passage 48, is, for example, 50°C to 220°C.

[0090] The smoke-preventing air discharged from the air outlet 12d of the smoke-preventing preheat exchanger 12 to the second air path section 54 is guided through the second air path section 54 to the air inlet 8c of the smoke-preventing main heat exchanger 8, and from the air inlet 8c is introduced into the main heat exchanger air passage 52. The temperature of the smoke-preventing air at the air inlet 8c of the smoke-preventing main heat exchanger 8, in other words, the temperature of the smoke-preventing air at the upstream end of the main heat exchanger air passage 52, is similar to the temperature of the smoke-preventing air at the air outlet 12d of the smoke-preventing preheat exchanger 12, for example, between 50°C and 220°C.

[0091] In the white smoke prevention main heat exchanger 8, heat exchange takes place between the white smoke prevention air flowing through the main heat exchanger air passage 52 and the exhaust gas flowing through the main heat exchanger exhaust gas passage 51, and the white smoke prevention air is further heated by the heat of the exhaust gas. The white smoke prevention air heated in the white smoke prevention main heat exchanger 8 is discharged from the downstream end of the main heat exchanger air passage 52 through the air outlet 8d to the third air passage section 56. The temperature of the white smoke prevention air at the air outlet 8d of the white smoke prevention main heat exchanger 8, in other words, the temperature of the white smoke prevention air at the downstream end of the main heat exchanger air passage 52, is, for example, 300°C to 550°C.

[0092] The white smoke prevention air discharged from the air outlet 8d of the white smoke prevention main heat exchanger 8 to the third air path section 56 is introduced into the hot water boiler 62 of the power generation equipment 16 via the third air path section 56. In the hot water boiler 62, the water is heated by the introduced white smoke prevention air to produce hot water. This hot water produced in the hot water boiler 62 is introduced into the power generation device 64. The power generation device 64 uses the introduced hot water as a heat source to generate electricity. The hot water used for power generation in the power generation device 64 returns to the hot water boiler 62, where it is heated again by the white smoke prevention air. In other words, water circulates between the hot water boiler 62 and the power generation device 64.

[0093] In the hot water boiler 62, the white smoke prevention air, which has been heated by heating the water, cools down and is discharged from the air outlet 62b of the hot water boiler 62 to the fourth air path section 58. The temperature of the white smoke prevention air at the air outlet 62b of the hot water boiler 62 is, for example, 100°C to 150°C.

[0094] The white smoke prevention air discharged from the air outlet 62b of the hot water boiler 62 to the fourth air path section 58 passes through the fourth air path section 58 and is introduced into the exhaust gas path 4 downstream of the wet scrubbing device 14, specifically at the downstream end of the exhaust gas path 4 (the downstream end of the sixth path section 26), and added to the exhaust gas. The temperature of this white smoke prevention air introduced into the exhaust gas path 4 is the same as the temperature of the white smoke prevention air at the air outlet 62b of the hot water boiler 62, and is higher than the temperature of the exhaust gas at the downstream end of the exhaust gas path 4. Therefore, this white smoke prevention air raises the temperature of the exhaust gas, thereby preventing the water vapor in the exhaust gas from condensing into white smoke even if the exhaust gas released into the atmosphere from the downstream end of the exhaust gas path 4 is cooled by the atmosphere.

[0095] The waste treatment method according to this embodiment is carried out by the series of processes described above. In this waste treatment method, after the start of waste treatment, the preheat exchanger exhaust gas flow path 47 is cleaned by the cleaning device 19 at regular intervals. Specifically, water is passed through the preheat exchanger exhaust gas flow path 47 by the cleaning device 19, thereby cleaning the inside of the preheat exchanger exhaust gas flow path 47.

[0096] In this embodiment, heat can be recovered from the exhaust gas into the white smoke prevention air by passing it through the white smoke prevention air in the order of the white smoke prevention pre-heat exchanger 12, which is located downstream of the white smoke prevention pre-heat exchanger 12, followed by the white smoke prevention main heat exchanger 8, which is located upstream of the wet smoke scrubbing device 14 on the exhaust gas path 4. This makes it possible to raise the temperature of the white smoke prevention air.

[0097] Specifically, in the waste treatment facility 101 according to the comparative example shown in Figure 4, exhaust gas discharged from the incinerator 102 flows through the exhaust gas path 104 in the following order: combustion air heat exchanger 106, white smoke prevention first main heat exchanger 108, white smoke prevention second main heat exchanger 109, wet smoke scrubbing device 110, and white smoke prevention pre-heat exchanger 112. Air sent from the blower 120 is first introduced to the white smoke prevention pre-heat exchanger 112 downstream of the wet smoke scrubbing device 110, where it is heated by heat exchange with the exhaust gas. After that, the air is introduced to the white smoke prevention first main heat exchanger 108, where it is heated by heat exchange with the exhaust gas, and then introduced to the white smoke prevention second main heat exchanger 109 downstream of the white smoke prevention first main heat exchanger 108, where it is further heated by heat exchange with the exhaust gas. In the exhaust gas path 104, the temperature of the exhaust gas decreases as you move downstream. Therefore, as in the waste treatment facility 101 in this comparative example, heat is recovered from the exhaust gas into the air by exchanging heat between the exhaust gas and air in the first main heat exchanger 108, which is located upstream of the first main heat exchanger 108 for preventing white smoke fumes 108 and the second main heat exchanger 109 for preventing white smoke fumes 109. Then, this air is introduced into the second main heat exchanger 109 for preventing white smoke fumes 109, where heat is further exchanged with the exhaust gas to recover heat into the air. In this case, the air that has first recovered heat through heat exchange with high-temperature exhaust gas is then exchanged with even lower-temperature exhaust gas to recover heat, resulting in the recovery of heat from the white smoke fumes air. The temperature will decrease.

[0098] In contrast, in this embodiment, heat is first recovered from the exhaust gas into the white smoke prevention air by exchanging heat between the exhaust gas and the white smoke prevention air in the downstream white smoke prevention preliminary heat exchanger 12, and then the white smoke prevention air from which the heat has been recovered is introduced into the upstream white smoke prevention main heat exchanger 8, where it further exchanges heat with the higher temperature exhaust gas, thereby recovering even more heat from the exhaust gas into the white smoke prevention air. As a result, the temperature of the white smoke prevention air obtained through heat exchange with the exhaust gas can be increased.

[0099] Furthermore, in this embodiment, since it is possible to prevent the surface temperature of the heat transfer section in the white smoke prevention main heat exchanger 8 from dropping to the point where condensation of exhaust gas occurs, by simply using highly corrosion-resistant materials for the first plate 49 and the second plate 50 that define the exhaust gas flow path 47 of the preheater heat exchanger 12, it is possible to prevent corrosion caused by exhaust gas condensation in both the white smoke prevention main heat exchanger 8 and the white smoke prevention preheater heat exchanger 12.

[0100] Specifically, in the waste treatment facility 101 according to the comparative example shown in Figure 4, the white smoke prevention preheat exchanger 112 exchanges heat between the exhaust gas after wet scrubbing treatment by the wet scrubbing device 110 and the air. Therefore, the temperature rise of the air heated by heat exchange with the exhaust gas, whose temperature has been significantly reduced by this wet scrubbing treatment, is minimal. Consequently, when this air is introduced from the white smoke prevention preheat exchanger 112 to the white smoke prevention first main heat exchanger 108 upstream, the temperature of the exhaust gas in the white smoke prevention first main heat exchanger 108 decreases significantly due to heat exchange between the air and the exhaust gas. If the temperature of the exhaust gas introduced into the white smoke prevention first main heat exchanger 108 is not very high to begin with, the heat exchange in the white smoke prevention first main heat exchanger 108 may lower the temperature of the exhaust gas to a temperature at which condensation occurs, potentially causing condensation of the exhaust gas. Furthermore, in the second main heat exchanger 109, which is located downstream of the first main heat exchanger 108 for preventing white smoke, the exhaust gas temperature is lower. Therefore, if condensation of exhaust gas occurs in the first main heat exchanger 108, condensation of exhaust gas will also occur in the second main heat exchanger 109. Consequently, in the waste treatment facility 101 according to this comparative example, condensation of exhaust gas may occur in both the first main heat exchanger 108 and the second main heat exchanger 109, which are located upstream of the wet scrubbing device 110, and there is a risk that corrosion may occur due to this condensation of exhaust gas.

[0101] In contrast, in this embodiment, the white smoke prevention preheat exchanger 12, located upstream of the wet fume scrubbing device 14, heats the white smoke prevention air, which is heated by heat exchange with the exhaust gas that, although lower in temperature than further upstream, maintains a relatively high temperature because it is before the wet fume scrubbing treatment. This heated white smoke prevention air is then introduced to the white smoke prevention main heat exchanger 8 further upstream, where it exchanges heat with the even higher temperature exhaust gas. This prevents the surface temperature of the heat transfer section from dropping to the point where condensation of the exhaust gas occurs due to the heat exchange in the white smoke prevention main heat exchanger 8. Therefore, if condensation of the exhaust gas occurs between the white smoke prevention main heat exchanger 8 and the white smoke prevention preheat exchanger 12, it is limited to the white smoke prevention preheat exchanger 12, which is located further downstream and where the temperature of the introduced exhaust gas and the temperature of the introduced white smoke prevention air are both lower than those on the upstream side. Therefore, by using a highly corrosion-resistant material for the first plate 49 and second plate 50 that define the exhaust gas flow path 47 of the white smoke prevention preheat exchanger 12, compared to the portion that defines the exhaust gas flow path 51 of the main heat exchanger in the white smoke prevention main heat exchanger 8, that is, by using a highly corrosion-resistant material for the first plate 49 and second plate 50 that define the exhaust gas flow path 47 of the preheat exchanger in the white smoke prevention preheat exchanger 12, corrosion caused by exhaust gas condensation can be prevented in both the white smoke prevention main heat exchanger 8 and the white smoke prevention preheat exchanger 12.

[0102] Furthermore, in this embodiment, in the white smoke prevention main heat exchanger 8, the surface temperature of the heat transfer section is determined by the exhaust gas Since it is possible to prevent the temperature from dropping to the point where dew forms, it is possible to avoid having to restrict the position of the main heat exchanger 8 on the exhaust gas path 4 in order to maintain the surface temperature of the heat transfer section of the main heat exchanger 8 in the white smoke prevention main heat exchanger 8 in a temperature range higher than the temperature at which condensation of the exhaust gas occurs, and the operating conditions of the incinerator 2 can be relaxed.

[0103] Specifically, in the exhaust gas path 4, the temperature of the exhaust gas decreases as you move downstream. Therefore, even if the temperature of the white smoke prevention air introduced into the white smoke prevention main heat exchanger 8 is low and the temperature of the heat transfer section of the white smoke prevention main heat exchanger 8 decreases, it is necessary to restrict the position of the white smoke prevention main heat exchanger 8 on the exhaust gas path 4 so that the surface temperature of the heat transfer section is maintained in a temperature range higher than the temperature at which condensation of the exhaust gas occurs. In contrast, in this embodiment, as described above, the white smoke prevention air heated by heat exchange with the exhaust gas, which maintains a relatively high temperature before wet scrubbing treatment, in the white smoke prevention preheating heat exchanger 12 is introduced into the white smoke prevention main heat exchanger 8. As a result, the surface temperature of the heat transfer section in the white smoke prevention main heat exchanger 8 does not decrease to the extent that condensation of the exhaust gas occurs. Therefore, it is possible to prevent the position of the white smoke prevention main heat exchanger 8 on the exhaust gas path 4 from becoming too restrictive. Furthermore, in order to maintain the surface temperature of the heat transfer section of the white smoke prevention main heat exchanger 8 at a temperature higher than the temperature at which condensation of exhaust gas occurs, the operating conditions of the incinerator 2 regarding the temperature of the exhaust gas discharged from the incinerator 2 can be relaxed.

[0104] Furthermore, in this embodiment, the white smoke prevention air, which has been heated in the white smoke prevention main heat exchanger 8 and passed through the white smoke prevention main heat exchanger 8, is introduced to the downstream end of the exhaust gas path 4 through the third air path section 56 and the fourth air path section 58 of the white smoke prevention air path 20. As a result, the white smoke prevention air introduced to the downstream end of the exhaust gas path 4 raises the temperature of the exhaust gas, preventing it from turning into white smoke when it is released into the atmosphere from that downstream end.

[0105] Furthermore, in this embodiment, the smoke-preventing air that has been heated in the smoke-preventing main heat exchanger 8 and passed through the smoke-preventing main heat exchanger 8 is introduced into the power generation equipment 16, and the power generation equipment 16 uses the thermal energy of the introduced smoke-preventing air to generate electricity. Therefore, in the waste treatment facility 1, which is capable of raising the temperature of the smoke-preventing air obtained by heat recovery from exhaust gas as described above, the recovered thermal energy can be effectively utilized to generate electricity.

[0106] Furthermore, in this embodiment, since dust contained in the exhaust gas is removed by the dust collector 10 located upstream of the white smoke prevention preheat exchanger 12 on the exhaust gas path 4, the exhaust gas introduced into the preheat exchanger exhaust gas passage 47 of the white smoke prevention preheat exchanger 12 does not contain dust, and thus it is possible to prevent the preheat exchanger exhaust gas passage 47 from being blocked by the dust. Moreover, even if condensation of exhaust gas occurs in the preheat exchanger exhaust gas passage 47, it is possible to avoid a situation where condensation containing corrosive components has difficulty escaping from the preheat exchanger exhaust gas passage 47 due to the aforementioned blockage, and in this way it is possible to prevent the acceleration of corrosion in the white smoke prevention preheat exchanger 12 caused by the aforementioned blockage. In addition, since it is possible to prevent the preheat exchanger exhaust gas passage 47 from being blocked as described above, it is possible to narrow the preheat exchanger exhaust gas passage 47, and as a result it becomes possible to make the white smoke prevention preheat exchanger 12 smaller.

[0107] Furthermore, since the dust collector 10 is located downstream of the white smoke prevention main heat exchanger 8 on the exhaust gas path 4, the exhaust gas that has been heated by the white smoke prevention air in the white smoke prevention main heat exchanger 8 and whose temperature has been reduced flows into the dust collector 10. Therefore, it is possible to avoid requiring the dust collector 10 to have high heat resistance.

[0108] Furthermore, in this embodiment, the cleaning device 19 can clean the inside of the preheat exchanger exhaust gas passage 47, so that corrosive components in the exhaust gas that have adhered to the inner wall surface of the preheat exchanger exhaust gas passage 47 can be washed away. Therefore, the occurrence of corrosion in the white smoke prevention preheat exchanger 12 can be prevented more reliably.

[0109] Furthermore, in this embodiment, the combustion air supply device 6 is configured to heat the combustion air using the thermal energy of the exhaust gas and supply it to the incinerator 2. If the combustion air were heated using an energy source unrelated to the thermal energy of the exhaust gas and supplied to the incinerator 2, additional energy would be consumed. However, in this embodiment, as described above, the combustion air supply device 6 heats the combustion air using the thermal energy of the exhaust gas and supplies it to the incinerator 2, thus reducing the amount of additional energy consumed.

[0110] Furthermore, the combustion air supply device 6 heats the combustion air by utilizing the thermal energy of the exhaust gas at a location upstream of the white smoke prevention main heat exchanger 8 on the exhaust gas path 4. As a result, the exhaust gas, whose temperature has been lowered by the utilization of the thermal energy of the exhaust gas by the combustion air supply device 6, is introduced into the white smoke prevention main heat exchanger 8. In this case, there is concern that the surface temperature of the heat transfer section of the white smoke prevention main heat exchanger 8 will drop to a temperature range where condensation of the exhaust gas occurs. However, as described above, the white smoke prevention air introduced into the white smoke prevention main heat exchanger 8 is heated to a relatively high temperature by the exhaust gas before wet scrubbing treatment in the white smoke prevention preheater 12. Therefore, the temperature of the exhaust gas that has exchanged heat with this white smoke prevention air prevents the surface temperature of the heat transfer section of the white smoke prevention main heat exchanger 8 from dropping to a temperature range where condensation of the exhaust gas occurs. Accordingly, in this embodiment, it is possible to reduce the energy separately consumed for heating the combustion air and supplying it to the incinerator 2, while also preventing corrosion caused by condensation of exhaust gas in the white smoke prevention main heat exchanger 8.

[0111] The type of waste incinerated in the incinerator 2 is not particularly limited, but it is preferable that the incinerator 2 incinerates waste containing ammonia components, and that the incineration of such waste generates exhaust gas containing ammonia components. Examples of waste containing ammonia components include sludge. Examples of sludge include dewatered sludge obtained by dewatering sludge produced from the treatment of sewage and wastewater, and dried sludge obtained by drying sludge, but are not limited to these. The ammonia contained in the exhaust gas reacts with acids, which are also contained in the exhaust gas and cause corrosion, thereby suppressing the occurrence of corrosion, especially in the preheat exchanger where the exhaust gas temperature is low and acids are easily generated. This makes it possible to simplify the corrosion prevention function (for example, by reducing the amount of corrosion-resistant material used in the preheat exchanger) and reduce costs.

[0112] For example, when the incineration of the aforementioned waste generates exhaust gas containing SOx or HCl, the SOx or HCl can become sulfuric acid or hydrochloric acid at relatively low temperatures, which can cause corrosion. However, the incineration of the aforementioned waste containing sludge generates ammonia that can undergo neutralization reactions as shown in (Chemical Formula 1) and (Chemical Formula 2) below, and this neutralization reaction can suppress acid-induced corrosion in the preheater (especially at low exhaust gas temperatures).

[0113] H2SO4 + 2NH3 → (NH4)2SO4 (Chemical Formula 1)

[0114] HCl+NH3→NH4Cl (chemical formula 2)

[0115] If ammonia is not present in the exhaust gas, high-temperature, high-concentration acids (e.g., 140°C; 60 wt% sulfuric acid) may adhere to the heat transfer parts of the heat exchanger (e.g., heat transfer plates and heat transfer tubes), potentially accelerating thinning due to corrosion (e.g., about 20 mm / year). However, ammonia contained in the exhaust gas generated by the incineration of waste containing sludge can effectively suppress the aforementioned thinning due to corrosion, dramatically improving the lifespan of the heat transfer parts. This also makes it possible to reduce costs by reducing the amount of highly corrosion-resistant materials used in the heat transfer parts.

[0116] (modified version) The waste treatment equipment and waste treatment method using the present invention are not necessarily limited to those described above. For example, the following configurations can be adopted in the waste treatment equipment and waste treatment method according to the present invention.

[0117] Instead of a bag filter, a ceramic filter or cyclone may be used as a dust collector. A ceramic filter uses a ceramic filter material to capture dust from exhaust gas and has high heat resistance. When using a bag filter, a gas cooler may be installed before the bag filter.

[0118] The dust collector may be positioned upstream of the main heat exchanger in the exhaust gas path to remove dust from the exhaust gas before it is introduced into the main heat exchanger. In this case, the temperature of the exhaust gas introduced into the dust collector will be higher than the temperature of the exhaust gas introduced into the dust collector 10, which is positioned downstream of the white smoke prevention main heat exchanger 8 and upstream of the white smoke prevention pre-heat exchanger 12, as in the above embodiment. For this reason, when the dust collector is positioned upstream of the main heat exchanger in this manner, it is preferable to use a ceramic filter with high heat resistance as the dust collector.

[0119] The power generation equipment may have a steam turbine that is driven by air that has been heated in a main heat exchanger and passed through the main heat exchanger, and power generation may be performed by driving the steam turbine. If a hot water boiler is used in the power generation equipment, the hot water heated by the hot water boiler may be hot water at 100°C or higher. Alternatively, the power generation equipment may be configured to generate power by supplying white smoke prevention air directly to the power generation device as a heat source, without using a hot water boiler or steam turbine. Or, it is also possible to use the remaining thermal energy of the heat exchange gas after a portion of the thermal energy has been recovered in the power generation equipment to prevent white smoke.

[0120] In the present invention, the combustion air supply device may be configured such that the turbine is driven by exhaust gas. Specifically, the turbine may be placed on the exhaust gas path and exhaust gas may be introduced from the exhaust gas path, the turbine may be driven by the introduced exhaust gas, and the compressor may be operated in conjunction with the driving of the turbine. Furthermore, the combustion air supply device does not have to use a supercharger, and may be composed of a fluid blower and an air preheater.

[0121] The main heat exchanger in the present invention may include a plurality of heat exchangers arranged in a line along the exhaust gas path, and the plurality of heat exchangers may be configured to sequentially exchange heat between air and exhaust gas.

[0122] Furthermore, the preheat exchanger and main heat exchanger in the present invention are not necessarily limited to those used for heating white smoke prevention air. That is, the preheat exchanger and main heat exchanger are not limited to those that exchange heat between the exhaust gas and air added to the exhaust gas at the downstream end of the exhaust gas path in order to raise the temperature of the exhaust gas at the downstream end in order to prevent the exhaust gas released into the atmosphere from becoming white smoke, but may simply be those that exchange heat between a heat exchange gas and the exhaust gas in order to recover heat from the exhaust gas.

[0123] The preheat exchanger exhaust gas passage and preheat exchanger air passage, which are installed inside the preheat exchanger, are not limited to a straight shape, but may also be meandering or have other shapes. Furthermore, the preheat exchanger exhaust gas passage and preheat exchanger air passage only need to be a space through which fluid can flow from the inlet to the outlet, and are not limited to elongated shapes in which the passage length is significantly larger than the passage width.

[0124] Furthermore, in a plate heat exchanger used as a preheater, grooves for forming flow channels may be formed on only one of the stacked first and second plates, while grooves are not formed on the other. That is, plates with grooves for forming flow channels and flat plates without grooves may be stacked alternately, with flat plates without grooves interposed between adjacent flow channels in the stacking direction.

[0125] Furthermore, the corrosion prevention function in the present invention does not necessarily require that the material of the portion of the preheat exchanger that defines the preheat exchanger exhaust gas flow path be used to prevent corrosion of that portion. That is, the material of the portion of the preheat exchanger that defines the preheat exchanger exhaust gas flow path may be a material having corrosion resistance equal to or less than that of the portion of the main heat exchanger that defines the main heat exchanger exhaust gas flow path. In this case, the corrosion prevention function may prevent corrosion of the portion that defines the preheat exchanger exhaust gas flow path by other means, for example, a cleaning device that cleans the inside of the preheat exchanger exhaust gas flow path.

[0126] Conversely, the corrosion prevention function in the present invention may prevent corrosion of the portion of the preheat exchanger that defines the preheat exchanger exhaust gas flow path solely through the high corrosion resistance of the material in that portion. In this case, the corrosion prevention function does not need to have a cleaning device.

[0127] Furthermore, the heat exchange gas sent to the preheat exchanger is not necessarily limited to white smoke prevention air consisting of outside air blown by a blower or other ventilation device. For example, exhaust gas after wet scrubbing treatment in a wet scrubbing device (flue treatment tower) may be supplied to the preheat exchanger as the heat exchange gas. Generally, an induction fan is provided downstream of the wet scrubbing device to draw in exhaust gas after wet scrubbing treatment, so it is sufficient to use this induction fan to supply some or all of the exhaust gas after wet scrubbing treatment drawn in from the wet scrubbing device to the preheat exchanger as the heat exchange gas. In this case, it is not necessary to provide a separate ventilation device to send the heat exchange gas to the preheat exchanger. Then, the exhaust gas after wet scrubbing treatment supplied to the preheat exchanger as the heat exchange gas is heated in the preheat exchanger, and then supplied to the main heat exchanger, where it is further heated. If a portion of the exhaust gas after wet scrubbing treatment is supplied to the main heat exchanger via a preheat exchanger as a heat exchange gas, the exhaust gas after wet scrubbing treatment, heated in the main heat exchanger, may be added to the exhaust gas at the downstream end of the exhaust gas path to prevent the exhaust gas discharged from that downstream end from becoming white smoke. In this case, the thermal energy contained in the exhaust gas after wet scrubbing treatment, heated in the main heat exchanger, may be used to generate electricity in the same manner as described in the above embodiment. Furthermore, if all of the exhaust gas after wet scrubbing treatment is supplied to the main heat exchanger via a preheat exchanger as a heat exchange gas, the exhaust gas after wet scrubbing treatment may be heated in the preheat exchanger and the main heat exchanger so that the exhaust gas discharged from the main heat exchanger does not produce white smoke. The heated exhaust gas may then be released directly into the atmosphere, or the heated exhaust gas may be maintained at a temperature that does not produce white smoke, heat may be recovered from the exhaust gas, and then released into the atmosphere. [Explanation of Symbols]

[0128] 1. Waste treatment facilities 2 Incinerator 4. Exhaust gas path 6. Combustion air supply device 8 White smoke prevention main heat exchanger (main heat exchanger) 10. Dust collector 12. White smoke prevention auxiliary heat exchanger (auxiliary heat exchanger) 14 Wet smoke cleaning equipment 15. Corrosion prevention function part 16 Power generation facilities 19. Washing device 47. Exhaust gas flow path for auxiliary heat exchanger 51 Main heat exchanger exhaust gas flow path 56 Third air passage section (heated gas passage) 58. Fourth air passage section (heated gas passage)

Claims

1. A waste treatment facility that processes waste, An incinerator for burning the aforementioned waste, An exhaust gas path through which exhaust gas discharged from the incinerator flows, A wet scrubbing device is arranged in the exhaust gas path and performs wet scrubbing treatment on the exhaust gas, A preheat exchanger is located upstream of the wet scrubbing device in the exhaust gas path and heats the heat exchange gas by exchanging heat between the exhaust gas and the heat exchange gas before the wet scrubbing treatment. The system includes a main heat exchanger located upstream of the preheater on the exhaust gas path, into which the heat exchange gas heated in the preheater is introduced and which is further heated by heat exchange with the exhaust gas, The main heat exchanger has a main heat exchanger exhaust gas passage through which the exhaust gas is introduced and flows. The aforementioned preheat exchanger has a preheat exchanger exhaust gas passage through which the exhaust gas is introduced and flows, and also has a corrosion prevention function that prevents corrosion of the portion of the preheat exchanger that defines the preheat exchanger exhaust gas passage. The corrosion prevention function unit is a waste treatment facility having a cleaning device for cleaning the exhaust gas flow path of the preheat exchanger.

2. The waste treatment equipment according to claim 1, wherein the corrosion prevention function is provided only in the pre-heat exchanger among the main heat exchanger and the pre-heat exchanger.

3. The corrosion prevention function part prevents corrosion of the portion of the preheat exchanger that defines the exhaust gas flow path of the preheat exchanger by using the material of that portion, and the material of that portion is a material with higher corrosion resistance than the material of the portion of the main heat exchanger that defines the exhaust gas flow path of the main heat exchanger, as described in claim 2.

4. The waste treatment equipment according to claim 3, wherein the material of the portion of the preheat exchanger that defines the preheat exchanger exhaust gas flow path is one of the following: a nickel alloy containing 40% by mass or more nickel, pure titanium, or a titanium alloy containing 50% by mass or more titanium.

5. Further equipped with a heating gas path, The waste treatment facility according to claim 1, wherein the heating gas path connects the main heat exchanger and the downstream end of the exhaust gas path, so that the heat exchange gas heated in the main heat exchanger and passing through the main heat exchanger is guided to the downstream end of the exhaust gas path and the heat exchange gas is added to the exhaust gas at the downstream end.

6. The waste treatment facility according to claim 1, further comprising a power generation facility that generates electricity using the thermal energy of the heat-exchanged gas that has been heated in the main heat exchanger and passed through the main heat exchanger.

7. The system further comprises a dust collector for collecting dust contained in the exhaust gas, The waste treatment facility according to claim 1, wherein the dust collector is located upstream of the preheater on the exhaust gas path.

8. The waste treatment facility according to claim 6, wherein the dust collector is located downstream of the main heat exchanger in the exhaust gas path.

9. The waste treatment facility according to claim 1, wherein the cleaning device is provided only for the pre-heat exchanger among the main heat exchanger and the pre-heat exchanger.

10. A waste treatment facility for treating waste, An incinerator for burning the aforementioned waste, An exhaust gas path through which exhaust gas discharged from the incinerator flows, A wet scrubbing device is arranged in the exhaust gas path and performs wet scrubbing treatment on the exhaust gas, A preheat exchanger is located upstream of the wet scrubbing device in the exhaust gas path and heats the heat exchange gas by exchanging heat between the exhaust gas and the heat exchange gas before the wet scrubbing treatment. A main heat exchanger is located upstream of the preheater on the exhaust gas path, and into which the heat exchange gas heated in the preheater is introduced and further heated by heat exchange with the exhaust gas. The incinerator includes a combustion air supply device that supplies combustion air used for burning the waste to the incinerator, The main heat exchanger has a main heat exchanger exhaust gas passage through which the exhaust gas is introduced and flows. The aforementioned preheat exchanger has a preheat exchanger exhaust gas passage through which the exhaust gas is introduced and flows, and also has a corrosion prevention function that prevents corrosion of the portion of the preheat exchanger that defines the preheat exchanger exhaust gas passage. A waste treatment facility comprising a combustion air supply device configured to heat the combustion air using the thermal energy of the exhaust gas located upstream of the main heat exchanger in the exhaust gas path, and to supply the heated combustion air to the incinerator.

11. A method for treating waste using a waste treatment facility described in any one of claims 1 to 10, A waste treatment method comprising: incinerating the waste in the incinerator, the exhaust gas generated by the incineration flowing through the exhaust gas path and, before being subjected to wet scrubbing treatment by the wet scrubbing device, being heated by heat exchange with a heat exchange gas in the preheat exchanger, and the heat exchange gas heated in the preheat exchanger being introduced into the main heat exchanger and further heated by heat exchange with the exhaust gas in the main heat exchanger.

12. The waste treatment method according to claim 11, wherein the incinerator incinerates waste containing ammonia components, and exhaust gas containing ammonia components is generated by the incineration of the waste.

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