JP7653397B2 - Waste treatment equipment and waste treatment method - Google Patents

Description

The present invention relates to a waste treatment facility and a waste treatment method.

Some waste treatment facilities that incinerate waste are equipped with a heat exchanger that exchanges heat between exhaust gas and a heat transfer medium (see, for example, Patent Documents 1 and 2).

The pressurized fluidized furnace system disclosed in Patent Document 1 includes a pressurized fluidized furnace for burning materials to be treated, an air preheater for heating the combustion gas to be supplied to the pressurized fluidized furnace with the combustion exhaust gas discharged from the pressurized fluidized furnace, a dust collector for removing dust and the like in the combustion exhaust gas discharged from the pressurized fluidized furnace, a turbocharger driven by the combustion exhaust gas to supply combustion air to the pressurized fluidized furnace, a white smoke prevention heat exchanger for heating the white smoke prevention air with the combustion exhaust gas supplied from the turbocharger, and an exhaust smoke treatment device for removing impurities in the combustion exhaust gas. The white smoke prevention heat exchanger indirectly exchanges heat between the combustion exhaust gas discharged from the turbocharger turbine and the white smoke prevention air supplied from the white smoke prevention blower, thereby raising the temperature of the white smoke prevention air and lowering the temperature of the combustion exhaust gas.

The equipment disclosed in Patent Document 2 comprises a boiler or refuse incinerator (hereinafter referred to as "incinerator"), an air preheater, a high-temperature heat exchanger, a wet flue gas treatment device, and a low-temperature heat exchanger, which are connected in this order to a gas duct through which the combustion gas generated in the incinerator flows. The low-temperature heat exchanger and the high-temperature heat exchanger are connected by an air duct through which air supplied by a forced draft fan flows. The combustion gas passes through the gas duct and enters the high-temperature heat exchanger, where it exchanges heat with the air from the low-temperature heat exchanger. The combustion gas leaving the high-temperature heat exchanger is desulfurized or denitrified in the wet flue gas treatment device and is then led to the low-temperature heat exchanger.

JP 2019-15485 A Japanese Unexamined Patent Publication No. 52-74133

In a heat exchanger that exchanges heat between exhaust gas and a heat medium as disclosed in Patent Documents 1 and 2, there may be a portion where the temperature of the heat transfer surface between the exhaust gas and the heat medium is below the sulfuric acid dew point. In the portion where the temperature of the heat transfer surface of the heat exchanger is below the sulfuric acid dew point, sulfur trioxide and the like contained in the SOx in the exhaust gas condenses and adheres to the heat transfer surface of the heat exchanger. If this condensate adheres to the heat transfer surface of the heat exchanger, corrosion of the heat transfer surface of the heat exchanger becomes a problem. In particular, the exhaust gas generated when burning a combustible material whose properties are unstable, such as waste, contains various components, so condensates of various components adhere to the heat transfer surface, causing corrosion of the heat transfer surface of the heat exchanger. This phenomenon is likely to occur in relatively low-temperature exhaust gas that flows downstream of the dust collector in the exhaust gas flow direction.

For these reasons, it is desirable to suppress corrosion of heat exchangers using a simple configuration.

The waste treatment facility according to the present invention is characterized in that it comprises an incinerator for incinerating waste, a dust collector for collecting dust contained in the exhaust gas discharged from the incinerator, a smoke scrubber that is provided downstream of the dust collector in the exhaust gas flow direction of the exhaust gas and performs a smoke scrubbing process to purify the exhaust gas, and a low-temperature heat exchanger that is provided between the dust collector and the smoke scrubber and recovers heat from the exhaust gas by performing heat exchange between the exhaust gas and a heat exchange gas. The low-temperature heat exchanger has a plurality of partition members that separate a heat exchange gas passage through which the heat exchange gas flows and an exhaust gas passage through which the exhaust gas flows, and a cleaning device that cleans the partition members with a cleaning liquid, and the cleaning waste liquid after cleaning the partition members is led to the smoke scrubber.

With this configuration, the cleaning waste liquid is led to the smoke washing device, eliminating the need to provide a separate wastewater treatment facility for draining the cleaning waste liquid. Since the cleaning waste liquid contains condensate, it is possible to dispose of it all at once in the smoke washing device. As a result, the configuration of the waste treatment facility can be prevented from becoming too complicated.

In addition, with this configuration, the low-temperature heat exchanger is provided downstream of the dust collector in the exhaust gas flow direction, so that the thermal energy of the lower-temperature exhaust gas can be recovered. This allows the heat of the exhaust gas to be recovered without waste, improving the heat recovery rate of the exhaust gas. Moreover, because the low-temperature heat exchanger performs gas-to-gas heat exchange in which the low-temperature heat exchanger is heated by the heat of the exhaust gas via the partition member, the temperature of the clean heat exchange gas can be increased, making it possible to use it for various purposes such as power generation.

In addition, when heat is recovered from exhaust gas in a low-temperature heat exchanger, the temperature of the heat transfer surface of the partition member drops, and the drop in temperature of the heat transfer surface makes it easier for condensates of components contained in the exhaust gas to adhere to the partition member. With this configuration, the condensate adhering to the partition member is removed by washing it with a cleaning liquid by the washing device. Since this washing device is incorporated in the waste treatment facility, it is possible to wash the partition member with condensate adhering thereto during operation, and it is possible to prevent the condensate from adhering to the partition member for a long period of time. As a result, acid corrosion of the partition member can be suppressed. Therefore, corrosion of the heat exchanger can be suppressed with a simple configuration.

As another feature, the low-temperature heat exchanger may further have a flue connected to the smoke scrubbing device through which the exhaust gas is discharged toward the smoke scrubbing device, and the washing waste liquid may be guided to the smoke scrubbing device via the flue.

With this configuration, the cleaning waste liquid is guided to the smoke washing device using the flue through which exhaust gas is discharged toward the smoke washing device, eliminating the need to provide a separate drainage channel for draining the cleaning waste liquid, which makes it possible to prevent the waste treatment facility from becoming too complicated.

As another feature, the low-temperature heat exchanger may have a tank for storing the cleaning waste liquid and a pump for transporting the cleaning waste liquid stored in the tank, and the cleaning waste liquid may be guided to the smoke washing device by the pump.

With this configuration, the cleaning waste liquid stored in the tank is transported by a pump and directed to the smoke washer, eliminating restrictions on the relative positions of the low-temperature heat exchanger and the smoke washer, improving the freedom of design of the waste treatment facility.

As another feature, the partition member may include a flat plate member having a flat heat transfer surface, the exhaust gas passage may be formed between a pair of the plate members, and the heat exchange gas passage may be formed between adjacent exhaust gas passages.

With this configuration, the heat of the exhaust gas and the heat of the heat exchange gas can be exchanged on the flat heat transfer surface of the flat plate member, improving the heat recovery rate of the low-temperature heat exchanger. In addition, the cleaning liquid flows smoothly and can come into uniform contact with the heat transfer surface, improving the cleaning efficiency.

The waste treatment method according to the present invention is characterized in that it is a waste treatment method in a waste treatment facility equipped with an incinerator for incinerating waste, and includes a dust collection step for collecting dust contained in exhaust gas discharged from the incinerator, a heat recovery step for recovering heat from the exhaust gas by performing heat exchange between the collected exhaust gas and a heat exchange gas, and a smoke washing step for purifying the exhaust gas from which the heat has been recovered, and the heat recovery step includes a cleaning step for cleaning a partition member that separates a heat exchange gas passage through which the heat exchange gas flows and an exhaust gas passage through which the exhaust gas flows, by a cleaning device, and in the cleaning step, the cleaning liquid after cleaning the partition member is led to a smoke washing device that performs the smoke washing step.

This method can achieve the same effects as the waste treatment facility described above.

1 is a schematic diagram of a waste treatment facility according to an embodiment; FIG. 2 is a schematic diagram showing a configuration of a white smoke prevention reserve heat exchanger according to the embodiment. 5A and 5B are diagrams illustrating configurations of a heat exchange section and a cleaning section according to the embodiment. FIG. 4 is a perspective view showing a plate member according to the embodiment. FIG. 2 is a diagram showing a configuration of a cleaning unit according to the embodiment. FIG. 2 is a block diagram showing a configuration of a white smoke prevention reserve heat exchanger according to the embodiment. FIG. 2 is a diagram showing the configuration of a white smoke prevention preliminary heat exchanger and a wet smoke washing device according to the embodiment. FIG. 11 is a diagram showing the configuration of a white smoke prevention preliminary heat exchanger and a wet smoke washing device according to another embodiment. FIG. 11 is a diagram showing the configuration of a white smoke prevention preliminary heat exchanger and a wet smoke washing device according to another embodiment. FIG. 11 is a diagram showing the configuration of a white smoke prevention preliminary heat exchanger and a wet smoke washing device according to another embodiment.

Below, an embodiment of a waste treatment facility and a waste treatment method equipped with a white smoke prevention spare heat exchanger as a low-temperature heat exchanger according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications are possible without departing from the spirit of the present invention.

[Outline of waste treatment facility]
As shown in FIG. 1 , the waste treatment facility 100 includes an incinerator 10, a combustion air supply device 20, a white smoke prevention main heat exchanger 30, a dust collection device 40, a white smoke prevention reserve heat exchanger 50 (an example of a low-temperature heat exchanger), a wet smoke washing device 60, and a power generation facility 70.

The waste treatment facility 100 further includes an exhaust gas passage R1 (an example of a flue) through which exhaust gas generated when the waste is burned in the incinerator 10 flows. The incinerator 10, the combustion air supply device 20, the white smoke prevention main heat exchanger 30, the dust collection device 40, the white smoke prevention reserve heat exchanger 50, the wet smoke washing device 60, and the chimney (not shown) are connected via the exhaust gas passage R1. Hereinafter, the flow direction of the exhaust gas flowing through the exhaust gas passage R1 is referred to as the "exhaust gas flow direction D1."

[Exhaust gas passage]
The incinerator 10 incinerates waste such as dewatered sludge. Exhaust gas generated by burning the waste is discharged toward the combustion air supply device 20 via an exhaust gas passage R1. The exhaust gas contains chlorine compounds such as hydrogen chloride and corrosive substances such as sulfur oxides. In this embodiment, the incinerator 10 is a fluidized bed incinerator. However, the incinerator 10 may be an incinerator other than a fluidized bed incinerator (for example, a stoker incinerator).

The combustion air supply device 20 supplies the incinerator 10 with combustion air that is used when burning waste in the incinerator 10. The combustion air supply device 20 is provided downstream of the incinerator 10 in the exhaust gas flow direction D1, and exhaust gas discharged from the incinerator 10 is introduced into the combustion air supply device 20.

The combustion air supply device 20 has a combustion air heat exchanger 21 and a turbocharger 22. The combustion air supply device 20 may have a fluidized bed blower instead of the turbocharger 22.

The combustion air heat exchanger 21 exchanges heat between the exhaust gas discharged from the incinerator 10 and the combustion air. This cools the exhaust gas and heats the combustion air. The combustion air heated by the combustion air supply device 20 is supplied to the incinerator 10 via the turbocharger 22.

The turbocharger 22 supplies compressed combustion air to the combustion air heat exchanger 21. The turbocharger 22 includes a turbine 221, a shaft 222, and a compressor 223. The turbine 221 rotates due to the pressure and thermal energy of the air heated by the combustion air heat exchanger 21. The shaft 222 transmits the rotational force of the turbine 221 to the compressor 223. The compressor 223 compresses the combustion air using the rotational force transmitted by the shaft 222. The combustion air compressed by the compressor 223 is introduced into the combustion air heat exchanger 21.

The white smoke prevention main heat exchanger 30 is provided downstream of the combustion air supply device 20 in the exhaust gas flow direction D1, and the exhaust gas after heat exchange in the combustion air supply device 20 is introduced into the white smoke prevention main heat exchanger 30. The white smoke prevention main heat exchanger 30 is a type of heat exchanger, and is a multi-tube heat exchanger or a plate heat exchanger.

The white smoke prevention main heat exchanger 30 is provided to prevent the exhaust gas discharged from the chimney from being cooled in the atmosphere and turning into white smoke. The white smoke prevention main heat exchanger 30 exchanges heat between the exhaust gas introduced from the combustion air supply device 20 and air (hereinafter referred to as "white smoke prevention air"). This cools the exhaust gas and heats the white smoke prevention air. The white smoke prevention air is introduced by being pushed out from a blower B further provided in the waste treatment facility 100. The path through which the white smoke prevention air flows (hereinafter referred to as "white smoke prevention air path R2") will be described later.

The dust collector 40 is provided downstream of the white smoke prevention main heat exchanger 30 in the exhaust gas flow direction D1, and the exhaust gas after heat exchange in the white smoke prevention main heat exchanger 30 is introduced into the dust collector 40. The dust collector 40 collects dust contained in the exhaust gas (dust collection step). In this embodiment, the dust collector 40 is composed of a bag filter. However, the dust collector 40 is not limited to being composed of a bag filter, and may be composed of a ceramic filter or the like.

The white smoke prevention reserve heat exchanger 50 is provided downstream of the dust collector 40 in the exhaust gas flow direction D1, and exhaust gas after dust collection by the dust collector 40 is introduced into the white smoke prevention reserve heat exchanger 50. The white smoke prevention reserve heat exchanger 50 is a type of heat exchanger, and in this embodiment is a plate-type heat exchanger. Because the white smoke prevention reserve heat exchanger 50 is a plate-type heat exchanger, heat exchange is performed over a wide heat transfer surface.

The white smoke prevention reserve heat exchanger 50 is provided to prevent the exhaust gas discharged from the chimney from being cooled in the atmosphere and turning into white smoke. Exhaust gas at a lower temperature than the exhaust gas introduced into the white smoke prevention main heat exchanger 30 is introduced into the white smoke prevention reserve heat exchanger 50. For this reason, the white smoke prevention reserve heat exchanger 50 is sometimes called the "low-temperature heat exchanger" and the white smoke prevention main heat exchanger 30 is sometimes called the "high-temperature heat exchanger."

The white smoke prevention reserve heat exchanger 50 uses the thermal energy of the introduced exhaust gas to heat the white smoke prevention air (an example of a heat exchange gas). In detail, the white smoke prevention reserve heat exchanger 50 exchanges heat between the exhaust gas introduced from the dust collector 40, i.e., the exhaust gas after dust has been removed, and the white smoke prevention air. This cools the exhaust gas (recovers the heat of the exhaust gas) and heats the white smoke prevention air (heat recovery step). The temperature of the exhaust gas introduced into the white smoke prevention reserve heat exchanger 50 is 160 degrees or more and 250 degrees or less. By performing heat exchange in the white smoke prevention reserve heat exchanger 50, the temperature of the exhaust gas is reduced to 50 degrees or more and 150 degrees or less.

The wet smoke scrubbing device 60 is provided downstream of the white smoke prevention reserve heat exchanger 50 in the exhaust gas flow direction D1, and the exhaust gas after heat exchange in the white smoke prevention reserve heat exchanger 50 is introduced into the wet smoke scrubbing device 60. The wet smoke scrubbing device 60 (an example of a smoke scrubbing device) performs a smoke scrubbing process to purify the exhaust gas (smoke scrubbing step). In this embodiment, the wet smoke scrubbing device 60 purifies the exhaust gas by the wet smoke scrubbing process and removes moisture in the exhaust gas by dehumidification and cooling. Circulating water containing a chemical agent is used to purify the exhaust gas. Cooling water is used to dehumidify and cool the exhaust gas. The amount of exhaust gas is reduced by removing moisture in the exhaust gas by dehumidification and cooling. The purified exhaust gas flows toward a chimney (not shown).

[White smoke prevention air path]
The waste treatment facility 100 further includes a white smoke prevention air passage R2 through which the white smoke prevention air flows. Hereinafter, the flow direction of the white smoke prevention air flowing through the white smoke prevention air passage R2 will be referred to as an "air flow direction D2".

The white smoke prevention air path R2 connects the blower B, which sends out white smoke prevention air, the white smoke prevention reserve heat exchanger 50, the white smoke prevention main heat exchanger 30, the power generation equipment 70, and the chimney (not shown).

The white smoke prevention reserve heat exchanger 50 is provided downstream of the blower B in the air flow direction D2, and the white smoke prevention air sent out from the blower B is introduced into the white smoke prevention reserve heat exchanger 50. The temperature of the white smoke prevention air introduced into the white smoke prevention reserve heat exchanger 50 is the same as the outside air temperature, and is between 0 and 50 degrees. The temperature of the white smoke prevention air rises to between 50 and 220 degrees by exchanging heat with the exhaust gas.

The white smoke prevention main heat exchanger 30 is provided downstream of the white smoke prevention reserve heat exchanger 50 in the air flow direction D2, and the white smoke prevention air after heat exchange in the white smoke prevention reserve heat exchanger 50 is introduced into the white smoke prevention main heat exchanger 30. The temperature of the white smoke prevention air introduced into the white smoke prevention main heat exchanger 30 is 50 degrees or more and 220 degrees or less (for example, around 125 degrees). The temperature of the white smoke prevention air increases to 220 degrees or more and 550 degrees or less by heat exchange in the white smoke prevention main heat exchanger 30. It is preferable that the heat recovery amount of the white smoke prevention main heat exchanger 30 is configured to be equal to or greater than the heat recovery amount of the white smoke prevention reserve heat exchanger 50 (for example, 1 to 5 times).

The power generation equipment 70 is provided downstream of the white smoke prevention main heat exchanger 30 in the air flow direction D2, and the white smoke prevention air that has been heat exchanged (heated) in the white smoke prevention main heat exchanger 30 is introduced into the power generation equipment 70. The power generation equipment 70 generates electricity by using the thermal energy of the white smoke prevention air that has been heated in the white smoke prevention main heat exchanger 30.

The power generation facility 70 includes a hot water boiler 71, a circulation path 72, and a power generation device 73.

The hot water boiler 71 uses the thermal energy of the white smoke prevention air to heat water. The heated water (hot water) is introduced into the power generation device 73 via the circulation path 72.

The circulation path 72 connects the hot water boiler 71 and the power generation device 73, and circulates water between the hot water boiler 71 and the power generation device 73.

The power generation device 73 generates power using water (hot water) introduced from the hot water boiler 71 via the circulation path 72 as a heat source. After being used for power generation, the water is introduced into the hot water boiler 71 via the circulation path 72. In this embodiment, the power generation device 73 is a binary power generation device.

The white smoke prevention air from which thermal energy has been recovered in the hot water boiler 71 is introduced downstream of the wet smoke scrubbing device 60 in the exhaust gas passage R1 and merges with the exhaust gas discharged from the wet smoke scrubbing device 60. The temperature of the white smoke prevention air that merges with the exhaust gas is between 100°C and 200°C.

The exhaust gas discharged from the wet smoke scrubbing device 60 is heated by merging with the white smoke prevention air. The exhaust gas heated by the white smoke prevention air is discharged into the atmosphere from a chimney (not shown). As described above, the exhaust gas is cooled stepwise by the white smoke prevention main heat exchanger 30 and the white smoke prevention reserve heat exchanger 50, and is finally cooled by the wet smoke scrubbing device 60, and then heated by the white smoke prevention air that has passed through the power generation equipment 70 before being discharged from the chimney. The effect of reducing the moisture content of the exhaust gas before being discharged from the chimney and increasing the temperature of the exhaust gas prevents the exhaust gas discharged from the chimney from becoming white smoke.

[White smoke prevention spare heat exchanger]
2, the white smoke prevention preliminary heat exchanger 50 has a housing 51, a heat exchange unit 52, and a cleaning unit 53 (an example of a cleaning device). The heat exchange unit 52 and a part of the cleaning unit 53 are accommodated in the housing 51.

[Heat exchange section]
The heat exchange section 52 includes a heat exchange unit 521 that exchanges heat between the exhaust gas and the white smoke prevention air. The heat exchange unit 521 includes a plurality of plate members 522 (an example of a partition member).

[Plate member]
3, the plate member 522 separates a heat exchange exhaust gas passage R51 (an example of an exhaust gas passage) through which exhaust gas flows and a heat exchange air passage R52 (an example of a heat exchange gas passage) through which white smoke prevention air flows inside the white smoke prevention reserve heat exchanger 50. Inside the white smoke prevention reserve heat exchanger 50, a plurality of heat exchange exhaust gas passages R51 and a plurality of heat exchange air passages R52 are formed in parallel, and the heat exchange exhaust gas passages R51 and the heat exchange air passages R52 are provided alternately. The heat exchange exhaust gas passage R51 is the exhaust gas passage R1 inside the white smoke prevention reserve heat exchanger 50, and the heat exchange air passage R52 is the white smoke prevention air passage R2 inside the white smoke prevention reserve heat exchanger 50.

As shown in Figures 3 and 4, the plate member 522 is flat and has a main surface 522s. The multiple plate members 522 are spaced apart so that the main surfaces 522s are parallel to each other. In this embodiment, the main surfaces 522s are flat, but at least one of the main surfaces 522s may have minute irregularities such as grooves or protrusions.

The heat exchange exhaust gas passage R51 is formed between opposing plate members 522. As shown in FIG. 4, the heat exchange exhaust gas passage R51 is formed, for example, by joining one end 522e (hereinafter referred to as the "first end 522e") of the opposing plate members 522 by welding or the like. Note that the dashed dotted line shown in FIG. 4 indicates the welded portion. Hereinafter, the two plate members 522 opposing each other across the heat exchange exhaust gas passage R51 are referred to as a "pair of plate members 522t."

3, the heat exchange air passage R52 is formed between the adjacent heat exchange exhaust gas passages R51. As shown in FIG. 4, the heat exchange air passage R52 is formed by joining the second end 522f of the first joining plate 522A and the second joining plate 522B of the pair of adjacent plate members 522t. The second end 522f is an end in a direction perpendicular to the first end 522e of the plate member 522, and is formed between the adjacent first end 522e in a plan view (viewed in a direction along the main surface 522s). The first joining plate 522A is one plate member 522 of the pair of plate members 522t. The second joining plate 522B is a plate member 522 of the pair of plate members 522t adjacent to the first joining plate 522A that faces the first joining plate 522A through the heat exchange air passage R52.

When viewed from a direction perpendicular to the main surface 522s of the plate member 522, the heat exchange exhaust gas passage R51 and the heat exchange air passage R52 overlap with each other so as to sandwich the main surface 522s. Therefore, the main surface 522s of the plate member 522 functions as a heat transfer surface for heat exchange between the exhaust gas flowing through the heat exchange exhaust gas passage R51 and the white smoke prevention air flowing through the heat exchange air passage R52.

The plate member 522 can be made of a material selected from pure titanium, titanium alloy, stainless steel, nickel alloy, etc. Nickel alloys include, for example, Hastelloy (registered trademark) (Hastelloy C-22, Hastelloy C-276, Hastelloy C-4, Hastelloy C-22HS, Hastelloy C-2000, Hastelloy HYBRID-BC1, other Hastelloys), ALLOY (ALLOY 22, ALLOY C-276), Inconel (registered trademark) (Inconel 600, Inconel 625, Inconel 718), etc. Nickel alloys are suitable as materials for the plate member 522 because of their excellent resistance to acid corrosion.

[Cleaning section]
As shown in Fig. 3, the cleaning unit 53 cleans the plate member 522 with a cleaning liquid L1 (cleaning step). The cleaning liquid L1 is a liquid for removing deposits (condensate) attached to the plate member 522, and in this embodiment, is water (tap water, industrial water, sand filtration water, sewage treatment water, etc.). The cleaning liquid L1 may be an alkaline aqueous solution containing sodium hydroxide or the like. The cleaning unit 53 cleans the plate member 522 at a predetermined interval (preset frequency). This removes deposits attached to the plate member 522, and acid corrosion of the plate member 522 can be suppressed.

As shown in FIG. 5, the cleaning section 53 includes a cleaning liquid supply section 532 and a cleaning unit 533.

The cleaning liquid supply unit 532 is supplied with cleaning liquid L1. The cleaning liquid supply unit 532 is connected to the cleaning unit 533 and supplies the cleaning liquid L1 to the cleaning unit 533.

The cleaning unit 533 includes a nozzle pipe 535, a plurality of nozzles 536, and a control valve 537. The nozzle pipe 535 and the plurality of nozzles 536 are provided inside the housing 51, and the control valve 537 is provided outside the housing 51.

The nozzle pipe 535 is connected to the cleaning liquid supply unit 532 via the control valve 537, and cleaning liquid L1 is supplied from the cleaning liquid supply unit 532.

As shown in FIG. 3, the nozzle pipe 535 extends in a direction perpendicular to the main surface 522s of the plate member 522, and multiple nozzles 536 are provided along the extension direction.

The nozzle 536 sprays the cleaning liquid L1. In this embodiment, the nozzle 536 sprays the cleaning liquid L1 at high pressure. However, the nozzle 536 may be a nozzle that sprays the cleaning liquid L1 at low pressure.

The control valve 537 controls the flow rate of the cleaning liquid L1 flowing through the nozzle pipe 535. The control valve 537 controls the amount of cleaning liquid L1 supplied from the nozzle 536 to the plate member 522 (hereinafter referred to as the "supply amount") by controlling the flow rate of the cleaning liquid L1 flowing through the nozzle pipe 535. In this embodiment, the control valve 537 is configured by combining a manual valve whose valve opening can be adjusted to a predetermined opening between fully open and fully closed, and an electromagnetic valve that switches ON (fully open)/OFF (fully closed) by timer operation.

The supply amount here is the amount of cleaning liquid L1 supplied to the heat exchange unit 521 per unit time (e.g., 24 hours) from the multiple nozzles 536 constituting the cleaning unit 533 corresponding to that heat exchange unit 521. Specifically, the supply amount is calculated based on a value obtained by multiplying the number of nozzles 536 constituting the cleaning unit 533, the amount of cleaning liquid L1 sprayed from one nozzle 536 at a time (L/piece), and the frequency at which the nozzles 536 spray the cleaning liquid L1 per unit time (e.g., 24 hours) (hereinafter referred to as the "spray frequency"). The spray amount (L/piece) is calculated by multiplying the amount of cleaning liquid L1 sprayed from one nozzle 536 per unit time (L/min.piece) by the spray time (min) of one nozzle 536.

The injection conditions (supply amount) such as injection frequency, injection amount, and injection time may be predetermined constant conditions, or may be set by a control device 55 further provided in the white smoke prevention reserve heat exchanger 50, as shown in FIG. 6.

The control device 55 controls the operation of the cleaning unit 53 (control valve 537). The control device 55 is, for example, a programmable logic controller (sequencer) or part of a distributed control system (DCS). Alternatively, the control device 55 may be a hard timer that measures the cleaning time or other time. The control device 55 may include a memory area that is made up of a processor such as a central processing unit (CPU) and a semiconductor memory such as a read only memory (ROM). A control program for controlling the operation of the cleaning unit 53 may be stored in the memory area.

[Cleaning solution]
As shown in Fig. 7, the cleaning liquid L1 (hereinafter referred to as "cleaning waste liquid L11") after cleaning the plate member 522 is led to the wet smoke scrubbing apparatus 60. In this embodiment, the cleaning waste liquid L11 is led to the wet smoke scrubbing apparatus 60 via an exhaust gas passage R15. The exhaust gas passage R15 is the exhaust gas passage R1 that connects the white smoke prevention reserve heat exchanger 50 and the wet smoke scrubbing apparatus 60 (see Fig. 1). The exhaust gas passage R15 is inclined downward toward the wet smoke scrubbing apparatus 60.

The wet smoke washing device 60 has a first smoke washing and cleaning liquid supply section 61 (cooling water line), a second smoke washing and cleaning liquid supply section 62 (circulating water line), a housing 63, a spraying device 64, a drainage tank 65, a neutralizing agent introduction section 66, a waste liquid drainage section 67, and a drainage tank 68. In this embodiment, the spraying device 64 includes a first spraying section 641 and a second spraying section 642.

The first smoke washing and cleaning liquid supply unit 61 has a cleaning liquid tank 611 that stores cleaning liquid L. Cleaning liquid L is stored in the cleaning liquid tank 611. The cleaning liquid L is water such as treated sewage water.

In this embodiment, the cleaning liquid L stored in the cleaning liquid tank 611 is supplied to the white smoke prevention reserve heat exchanger 50 and the wet smoke washing device 60. The liquid of the cleaning liquid L supplied to the white smoke prevention reserve heat exchanger 50 corresponds to the cleaning liquid L1, and the liquid supplied to the wet smoke washing device 60 corresponds to the smoke washing cleaning liquid L2. In the configuration shown in FIG. 7, the cleaning liquid supply unit 532 includes a supply pump 532a that transfers the cleaning liquid L1 from the cleaning liquid tank 611, and a cleaning liquid supply path 532b through which the cleaning liquid L1 transferred by the supply pump 532a flows and supplies the cleaning liquid L1 to the nozzle pipe 535, and the cleaning liquid L stored in the cleaning liquid tank 611 is transferred to the cleaning liquid supply path 532b as the cleaning liquid L1 by the supply pump 532a.

The first smoke scrubbing liquid supply unit 61 further includes a first smoke scrubbing pump 612 that transfers the scrubbing liquid L stored in the scrubbing liquid tank 611 as the smoke scrubbing liquid L2, and a first smoke scrubbing liquid supply path 613 through which the smoke scrubbing liquid L2 transferred by the first smoke scrubbing pump 612 flows. The first smoke scrubbing liquid supply unit 61 may also include a valve that adjusts the flow rate of the smoke scrubbing liquid L2 flowing through the first smoke scrubbing liquid supply path 613.

The first smoke cleaning liquid supply passage 613 is connected to the first spraying section 641 of the spraying device 64, and the smoke cleaning liquid L2 that flows through the first smoke cleaning liquid supply passage 613 is supplied to the first spraying section 641. The first spraying section 641 sprays the smoke cleaning liquid L2 supplied from the first smoke cleaning liquid supply section 61 into the housing 63 to dehumidify and cool the exhaust gas.

The first smoke scrubbing liquid supply unit 61 further includes a first smoke scrubbing liquid drainage unit 614 that drains the smoke scrubbing liquid L2 after spraying (hereinafter referred to as "post-spray smoke scrubbing liquid L21"). The post-spray smoke scrubbing liquid L21 is guided to the drainage tank 65 by the first smoke scrubbing liquid drainage unit 614. The drainage tank 65 receives the cleaning waste liquid L11 from the white smoke prevention reserve heat exchanger 50 via the exhaust gas passage R15, and the cleaning waste liquid L11 and the post-spray smoke scrubbing liquid L21 join in the drainage tank 65.

The neutralizing agent introduction section 66 introduces a neutralizing agent such as sodium hydroxide into the drainage tank 65. By introducing the neutralizing agent into the drainage tank 65, the cleaning waste liquid L11 and the post-spray smoke washing liquid L21 introduced into the drainage tank 65 are neutralized.

A portion of the neutralized cleaning waste liquid L11 and the post-spray smoke washing cleaning liquid L21 is discharged to the drain tank 68 by the waste liquid drain section 67. In addition, the remaining portion of the neutralized cleaning waste liquid L11 and the post-spray smoke washing cleaning liquid L21 can be reused as the smoke washing cleaning liquid L2.

The second smoke scrubbing liquid supply unit 62 circulates the smoke scrubbing liquid L2 between the drain tank 65 and the spray device 64 (second spray unit 642). The second smoke scrubbing liquid supply unit 62 includes a second smoke scrubbing pump 621 that transfers the neutralized cleaning liquid L in the drain tank 65 as the smoke scrubbing liquid L2, and a second smoke scrubbing liquid supply path 622 through which the smoke scrubbing liquid L2 transferred by the second smoke scrubbing pump 621 flows. The second smoke scrubbing liquid supply unit 62 may include a valve that adjusts the flow rate of the smoke scrubbing liquid L2 flowing through the second smoke scrubbing liquid supply path 622. The second smoke scrubbing liquid supply path 622 is connected to the second spray unit 642 of the spray device 64, and the smoke scrubbing liquid L2 that has flowed through the second smoke scrubbing liquid supply path 622 is supplied to the second spray unit 642.

The second spraying section 642 sprays the smoke cleaning liquid L2 supplied from the second smoke cleaning liquid supply section 62 into the housing 63. This purifies the exhaust gas in the housing 63. The second smoke cleaning liquid supply section 62 further includes a second smoke cleaning liquid drainage section 623 that drains the smoke cleaning liquid L2 (post-spray smoke cleaning liquid L21) after spraying. The post-spray smoke cleaning liquid L21 is led to the drainage tank 65 by the second smoke cleaning liquid drainage section 623.

[Effects of the embodiment]
As described above, according to this embodiment, since the white smoke prevention reserve heat exchanger 50 is provided downstream of the dust collector 40 in the exhaust gas flow direction D1, it is possible to recover thermal energy from lower temperature exhaust gas. As a result, the heat of the exhaust gas can be recovered without waste, and the heat recovery rate of the exhaust gas is improved. Moreover, since the white smoke prevention reserve heat exchanger 50 performs gas-to-gas heat exchange between the exhaust gas and the white smoke prevention air via the plate member 522, it is possible to increase the temperature of the clean white smoke prevention air and use it for various purposes such as power generation.

In addition, during exhaust gas heat recovery, the temperature of the heat transfer surface (main surface 522s) of the plate member 522 drops, and the drop in temperature of the heat transfer surface makes it easier for condensates of components contained in the exhaust gas to adhere to the plate member 522. According to this embodiment, the condensates adhering to the plate member 522 are removed by washing with the washing liquid L1 by the washing unit 53. Since this washing unit 53 is incorporated in the waste treatment equipment 100, it is possible to wash the plate member 522 to which the condensates are attached during operation, and it is possible to prevent the condensates from continuing to adhere to the plate member 522 for a long period of time. As a result, acid corrosion of the plate member 522 can be suppressed.

Furthermore, the cleaning waste liquid L11 is led to the wet smoke washing device 60. This eliminates the need to provide a separate wastewater treatment facility for draining the cleaning waste liquid L11, thereby preventing the waste treatment facility 100 from becoming too complicated in configuration.

[Another embodiment]
The present invention may be configured as follows other than the above-described embodiment (common numbers and symbols as in the embodiment are used for components having the same functions as in the embodiment).

(1) As shown in FIG. 8, the white smoke prevention reserve heat exchanger 50 may further include a waste liquid tank 538 for storing the cleaning waste liquid L11, and a cleaning waste liquid drainage section 539 for introducing the cleaning waste liquid L11 stored in the waste liquid tank 538 into the drainage tank 65. The cleaning waste liquid drainage section 539 includes a drainage pump 539a for transferring the cleaning waste liquid L11 stored in the waste liquid tank 538, and a waste liquid drainage channel 539b for guiding the cleaning waste liquid L11 transferred by the drainage pump 539a to the drainage tank 65. In this case, the waste liquid drainage channel 539b is connected to the drainage tank 65 provided at the bottom of the wet smoke washing device 60, so that the cleaning waste liquid L11 transferred by the drainage pump 539a is guided to the wet smoke washing device 60.

(2) Alternatively, as shown in FIG. 9, the white smoke prevention reserve heat exchanger 50 may further have a neutralizing agent introduction section 530 that introduces a neutralizing agent such as sodium hydroxide into the waste liquid tank 538 to neutralize the cleaning waste liquid L11. The cleaning waste liquid L11 neutralized in the waste liquid tank 538 is discharged from the drain tank 65 to the drain tank 68 by the waste liquid drain section 67 that discharges the smoke cleaning liquid L21 after spraying. In this case, the waste liquid drainage path 539b merges with the drain tank 68 of the wet smoke cleaning device 60, so that the cleaning waste liquid L11 transferred by the drain pump 539a is led to the wet smoke cleaning device 60.

In the configurations of Figures 8 and 9, the cleaning waste liquid L11 stored in the waste liquid tank 538 is transported by the drain pump 539a and directed to the wet smoke washing device 60, eliminating restrictions on the positional relationship between the white smoke prevention reserve heat exchanger 50 and the wet smoke washing device 60, improving the freedom of design of the waste treatment facility 100.

(3) Also, as shown in FIG. 10, the first smoke washing cleaning liquid supply passage 613 of the wet smoke washing device 60 may further include a first main passage 615 and a first branch flow passage 616 branched from the first main passage 615. The smoke washing cleaning liquid L2 branched from the first main passage 615 flows in the first branch flow passage 616 as cleaning liquid L1. The first branch flow passage 616 is connected to the cleaning liquid supply section 532 of the cleaning section 53 of the white smoke prevention reserve heat exchanger 50. The smoke washing cleaning liquid L2 branched from the first main passage 615, i.e., the cleaning liquid L1, is supplied to the nozzle pipe 535 via the first branch flow passage 616 and the cleaning liquid supply passage 532b. In other words, in this embodiment, the cleaning liquid L1 used to clean the cleaning unit 53 includes the smoke cleaning liquid L2 supplied from the wet smoke cleaning device 60 to the cleaning unit 53, and the smoke cleaning liquid L2 is branched from the first main passage 615 and supplied to the cleaning unit 53. Note that the smoke cleaning liquid L2 branched from the first main passage 615, i.e., the cleaning liquid L1, may be supplied directly to the nozzle pipe 535 from the first branch flow passage 616 without passing through the cleaning liquid supply passage 532b of the cleaning liquid supply unit 532.

(4) In the configuration of FIG. 10, the cleaning liquid supply unit 532 may further include a supply pump 532a (see FIG. 7) that transfers the cleaning liquid L1 from the cleaning liquid tank 611 as described with reference to FIG. 7. The configuration shown in FIG. 10 may also be combined with the configuration described with reference to FIG. 8 and FIG. 9. Specifically, the first smoke washing cleaning liquid supply path 613 shown in FIG. 8 and FIG. 9 may further include the first main passage 615 shown in FIG. 10 and the first branch flow path 616 branching from the first main passage 615, and the smoke washing cleaning liquid L2 branched from the first main passage 615 may be supplied to the cleaning liquid supply path 532b or the nozzle pipe 535 of the cleaning unit 53 via the first branch flow path 616 and used as the cleaning liquid L1.

(5) In addition, the cleaning liquid L1 guided to the drain tank 65 of the wet smoke cleaning device 60 may be used to neutralize the post-spray smoke cleaning liquid L21 after it has been sprayed by the spraying device 64 (after the exhaust gas has been purified).

(6) In the present embodiment, the white smoke prevention reserve heat exchanger 50 is a cross-flow plate-type heat exchanger. However, the white smoke prevention reserve heat exchanger 50 may be a counterflow, parallel flow, or other plate-type heat exchanger. In addition, the exhaust gas inlet 50a, exhaust gas outlet 50b, white smoke prevention air inlet 50c, and white smoke prevention air outlet 50d (see FIG. 2) in the white smoke prevention reserve heat exchanger 50 are not limited to those described in the embodiment and can be changed as appropriate. In this case, the flow direction of the exhaust gas and white smoke prevention air in the white smoke prevention reserve heat exchanger 50 can be changed as appropriate.

(7) In this embodiment, the case where there is one white smoke prevention main heat exchanger 30 has been described, but there may be multiple white smoke prevention main heat exchangers 30.

(8) In this embodiment, the white smoke prevention main heat exchanger 30 and the white smoke prevention reserve heat exchanger 50 are configured to heat the white smoke prevention air to prevent white smoke. However, the white smoke prevention main heat exchanger 30 and the white smoke prevention reserve heat exchanger 50 may be heat exchangers provided simply to recover heat from exhaust gas.

(9) In this embodiment, the dust collector 40 is provided downstream of the white smoke prevention main heat exchanger 30 in the exhaust gas flow direction D1, but the dust collector 40 may be provided upstream of the white smoke prevention main heat exchanger 30 in the exhaust gas flow direction D1.

(10) In this embodiment, the case where there is one heat exchange unit 521 has been described, but there may be two or more heat exchange units 521. When there are two or more heat exchange units 521, the cleaning units 533 are provided according to the number of heat exchange units 521.

(11) The number of nozzle pipes 535 included in the cleaning unit 533 can be changed as desired. In addition, the number of nozzles 536 provided on the nozzle pipes 535 can also be changed as desired. In addition, the number of nozzle pipes 535 connected to one control valve 537 can also be changed as desired.

(12) In this embodiment, the control valve 537 is a combination of a manual valve and a solenoid valve. However, the control valve 537 may be any valve whose valve opening degree can be controlled.

(13) In this embodiment, the case where the spray conditions (cleaning conditions) of the nozzle 536 are set by the control device 55 has been described, but the spray conditions may be set manually. For example, in a periodic inspection that is performed periodically, such as once a year or every six months, an engineer may set the spray conditions of the nozzle 536 based on the degree of corrosion of the plate member 522, etc. Note that the spray conditions are not limited to being set by an engineer, and may also be set by an operator, a worker, or the like.

(14) In this embodiment, the flat plate member 522 is used as a partition member. However, instead of the flat plate member 522, a plate member having a bent portion, such as a plate member bent in an uneven shape, may be used.

(15) In this embodiment, the cleaning unit 53 cleans the plate member 522 with the cleaning liquid L1 by spraying the cleaning liquid L1 from the multiple nozzles 536, but the method by which the cleaning unit 53 cleans the plate member 522 is not limited to this. For example, the cleaning unit 53 may clean the plate member 522 by dripping the cleaning liquid L1 from a hole provided in a pipe.

(16) In this embodiment, the pair of plate members 522t are arranged in parallel with a space between them so that the opposing main surfaces 522s are parallel to each other. However, the opposing main surfaces 522s of the pair of plate members 522 may be arranged at an incline so that they approach each other downstream in the exhaust gas flow direction D1. This allows, for example, the cleaning liquid L1 to remain on the downstream side of the opposing main surfaces 522s in the exhaust gas flow direction D1, and as a result, deposits attached to the main surfaces 522s can be more reliably removed.

(17) In this embodiment, the power generation equipment 70 includes a hot water boiler 71, a circulation path 72, and a power generation device 73. However, the power generation equipment 70 may also include a steam boiler, a water supply pump, a water supply tank, etc.

The present invention can be used in waste treatment facilities and waste treatment methods.

10: Incinerator 40: Dust collector 50: White smoke prevention spare heat exchanger (low-temperature heat exchanger)
53: Cleaning section (cleaning device)
60: Smoke cleaning device (wet type smoke cleaning device)
100: Waste treatment equipment 522: Plate member (partition member)
538: Waste liquid tank (tank)
539a: Drainage pump (pump)
D1: exhaust gas flow direction L1: cleaning liquid L11: cleaning waste liquid R15: exhaust gas passage (flue)
R51: Heat exchange exhaust gas passage (exhaust gas passage)
R52: Exchanger air passage (heat exchange gas passage)

Claims (5)

an incinerator for incinerating waste;
A dust collector that collects dust contained in the exhaust gas discharged from the incinerator;
a smoke washing device that is provided downstream of the dust collecting device in a flow direction of the exhaust gas and performs a smoke washing process to purify the exhaust gas;
a low-temperature heat exchanger provided between the dust collector and the smoke scrubbing device, for recovering heat from the exhaust gas by performing heat exchange between the exhaust gas and a heat exchange gas;
the low-temperature heat exchanger includes a plurality of partition members that separate a heat exchange gas passage through which the heat exchange gas flows and an exhaust gas passage through which the exhaust gas flows, and a cleaning device that cleans the partition members with a cleaning liquid,
The waste cleaning liquid after cleaning the partition member is guided to the smoke washing device. The low-temperature heat exchanger further includes a flue connected to the smoke scrubbing device, through which the exhaust gas is discharged toward the smoke scrubbing device;
The waste treatment facility according to claim 1 , wherein the scrubbing waste liquid is conducted to the smoke scrubbing device via the flue. The low-temperature heat exchanger includes a tank for storing the cleaning waste liquid;
a pump for transporting the cleaning waste liquid stored in the tank,
2. The waste treatment facility of claim 1, wherein the scrubbing waste liquid is conducted to the smoke scrubbing device by the pump. The partition member includes a flat plate member having a flat heat transfer surface,
The exhaust gas passage is formed between the pair of plate members,
The waste treatment facility according to any one of claims 1 to 3, wherein the heat exchange gas passage is formed between adjacent ones of the exhaust gas passages. A waste treatment method in a waste treatment facility equipped with an incinerator for incinerating waste, comprising:
A dust collection step of collecting dust contained in exhaust gas discharged from the incinerator;
a heat recovery step of recovering heat from the exhaust gas by performing heat exchange between the exhaust gas from which dust has been collected and a heat exchange gas;
A scrubbing step of purifying the exhaust gas from which heat has been recovered,
the heat recovery step includes a cleaning step of cleaning a partition member that separates a heat exchange gas passage through which the heat exchange gas flows and an exhaust gas passage through which the exhaust gas flows, by a cleaning device;
A waste treatment method, wherein in the cleaning step, the cleaning waste liquid after cleaning the partition member is guided to a smoke cleaning device that performs the smoke cleaning step.

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