JP2017194225A - Waste treatment facility and waste treatment method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste treatment facility and waste treatment method in which a superheater is difficult to corrode.SOLUTION: A waste treatment facility 10 includes: an incinerator 3 configured to incinerate a waste 11 or combustible gas occurring from the waste 11; a superheater 54 configured to exchange heat between exhaust gas and steam occurring in the incinerator 3 to thereby cool the exhaust gas and superheat the steam; and a first recovery unit 53 configured to fly ash contained in the exhaust gas with a temperature less than 700°C from a position between the incinerator 3 and the superheater 54.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a waste treatment facility that suppresses corrosion of a superheater by exhaust gas generated when incinerating waste such as municipal waste, and a waste treatment method using the waste treatment facility.

  Waste power generation that effectively uses waste such as municipal waste as a countermeasure against global warming is known. Waste power generation is a power generation method that effectively utilizes unused energy by converting the heat of exhaust gas generated when burning waste into electric power using a boiler and a steam turbine. In the waste power generation, fly ash is generated together with exhaust gas when the waste is burned. When waste contains chlorine components, such as sodium chloride and potassium chloride, the exhaust gas obtained by burning it also contains chlorine components. Patent Document 1 discloses a technique for making fly ash contain no chlorine component by collecting fly ash generated by combustion of waste at a high temperature and effectively using the fly ash as a cement raw material or the like (patent). Document 1, paragraphs [0003] and [0009]).

  For example, Patent Document 2 discloses a technique for adsorbing heavy metals such as Pb, Cd, As, and Se contained in exhaust gas to the heavy metal adsorbent by bringing the exhaust gas generated when the waste is burned into contact with the heavy metal adsorbent. Is disclosed. Thus, since the fly ash does not contain heavy metal by removing the heavy metal in the exhaust gas with the heavy metal adsorbent, the post-treatment of the fly ash becomes easy.

JP-A-11-300312 JP 2001-212427 A

  As described above, when waste containing chlorine components is processed by the waste processing methods disclosed in Patent Documents 1 and 2, the exhaust gas also contains chlorine components. On the other hand, in the case where the boiler includes a superheat transfer tube that exchanges heat between the high-temperature steam that has already evaporated and the exhaust gas, the superheat transfer pipe is caused by the heat of the steam and the chlorine component contained in the exhaust gas. There is a problem that molten salt corrosion is likely to occur in the heat pipe, and the heat transfer pipe (hereinafter also referred to as “superheater”) is thinned by the corrosion.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a waste treatment facility and a waste treatment method in which a superheater is hardly corroded.

  Conventionally, in order to divert fly ash in exhaust gas to cement raw materials, etc., fly ash with a low content of chlorine components such as sodium chloride and potassium chloride was recovered. We investigated the suppression of molten salt corrosion in the superheater by collecting the fly ash that contains a large amount of ash and thereby reducing the chlorine component that reaches the superheater. When the composition of fly ash due to the high and low exhaust gas temperature was investigated by thermodynamic simulation, almost all of the chlorine components in the fly ash were gaseous when the exhaust gas temperature was 800 ° C., whereas the exhaust gas temperature was lowered from 800 ° C. As a result, the chlorine component of the gas gradually changes to a liquid or solid state, and when the temperature of the exhaust gas is less than 700 ° C., the knowledge that almost all of the chlorine component is precipitated as liquid or solid fly ash is obtained. It was. Based on this knowledge, fly ash containing a large amount of chlorine component is effectively recovered, and the waste treatment facility of the present invention shown below is completed by intensive studies on a configuration that can reduce the chlorine component reaching the superheater. I let you.

  That is, the waste treatment facility of the present invention cools the exhaust gas by exchanging heat between the incinerator for incinerating the waste or the combustible gas generated from the waste, and the exhaust gas generated in the incinerator and the steam. In addition, a superheater that superheats the steam and a first recovery unit that recovers fly ash contained in the exhaust gas of less than 700 ° C. from a position between the incinerator and the superheater.

  According to the above configuration, by setting the exhaust gas to less than 700 ° C., most of the chlorine component contained in the exhaust gas becomes liquid or solid and precipitates as fly ash, and the first recovery unit until the fly ash reaches the superheater. It is possible to reduce the chlorine component reaching the superheater by recovering with. Thereby, since it becomes difficult for a chlorine component to adhere to the surface of a superheater, molten salt corrosion of a superheater can be suppressed. In the current waste treatment facility, the temperature of the superheated steam obtained by overheating with the superheater is at most 400 ° C. However, according to the waste treatment facility of the present invention, even if the superheater is set to a high temperature exceeding 400 ° C, There is little concern that molten salt corrosion will occur, and it will be possible to further increase the temperature of superheated steam.

  The said structure WHEREIN: It is preferable to further have a 2nd collection | recovery part which collect | recovers the fly ash contained in the exhaust gas of 800 degreeC or more from the position between an incinerator and a 1st collection | recovery part.

  According to the above configuration, when the exhaust gas is 800 ° C. or higher, the fly ash is less likely to contain the chlorine component due to the vaporization of the chlorine component. Therefore, the fly ash with a low content of the chlorine component is recovered in the second recovery unit. can do. The fly ash recovered in the second recovery part in this way can be effectively used as a cement raw material because the content of chlorine component is small. That is, according to the said structure, the fly ash which can be effectively utilized for cement raw materials etc. is collect | recovered previously in a 2nd collection part, and the fly ash which contains a large amount of chlorine components in the 1st collection part downstream from a 2nd collection part. It is possible to separately collect fly ash that can be effectively used as a raw material for cement and fly ash containing a large amount of chlorine component.

  In the above configuration, the cooling mechanism further includes a cooling mechanism that cools the exhaust gas generated in the incinerator, and the cooling mechanism includes the incinerator and the incinerator so that the exhaust gas supplied to the first recovery unit is cooled to less than 700 ° C. It is preferable that it is provided between the first recovery unit.

  According to the above configuration, since the exhaust gas is cooled by the cooling mechanism before the exhaust gas reaches the first recovery unit, the chlorine component in the exhaust gas is likely to be precipitated as fly ash, so the first recovery unit includes the chlorine component. It becomes easy to collect fly ash. As a result, the exhaust gas supplied to the superheater becomes difficult to contain a chlorine component, so that the superheater is prevented from being corroded by the chlorine component.

  In the above configuration, the cooling mechanism is an evaporator that boiles the water by heat exchange between the exhaust gas generated in the incinerator and water to generate steam supplied to the superheater and cools the exhaust gas. It is preferable.

  According to the said structure, the heat | fever of the waste gas generated in the incinerator can be utilized with an evaporator, and it can be set as the vapor | steam which boiled water in the said evaporator and is supplied to a superheater. By installing the evaporator in this way, the heat of the exhaust gas can be effectively used to evaporate water rather than simply cooling the exhaust gas.

  The said structure WHEREIN: It is preferable that a said 1st collection | recovery part collect | recovers the fly ash contained in the waste gas of 600 degreeC or more.

  In the current waste treatment facility, when the temperature of the steam flowing in the superheater is set to 400 ° C. or higher, a problem of molten salt corrosion occurs. According to the above configuration, fly ash containing chlorine components is collected by the first recovery unit. Therefore, it is possible to supply a high-temperature exhaust gas that hardly causes corrosion to the superheater. Thereby, it is possible to suppress the occurrence of molten salt corrosion in the superheater and to set the superheated steam flowing in the superheater to 400 ° C. or higher.

  The waste treatment method of the present invention cools the exhaust gas by heat-exchanging the waste or the combustible gas generated from the waste and the exhaust gas and steam generated by the incineration step. A step of superheating the steam, and a first step of recovering fly ash contained in the exhaust gas of less than 700 ° C. before the overheating step.

  According to the said structure, the chlorine component in waste gas can be collect | recovered by collect | recovering the fly ash contained in the waste gas below 700 degreeC by the 1st process before the process of heating exhaust gas. Thereby, since the chlorine component content of the exhaust gas supplied to the overheating step is reduced, it is possible to suppress the superheater used in the overheating step from being subjected to molten salt corrosion by the chlorine component. By making the superheater less susceptible to molten salt corrosion in this way, it is difficult to reduce the thickness of the superheater even if the temperature of the exhaust gas supplied in the overheating process is increased. Can be planned.

  The above configuration preferably further includes a second step of collecting fly ash contained in the exhaust gas at 800 ° C. or higher before the first step.

  In the state where the exhaust gas is 800 ° C. or higher, the chlorine component is vaporized, so that it becomes difficult to be recovered as fly ash. According to the second step, fly ash with a low chlorine component content can be recovered, and since the fly ash has a low chlorine component content, it can be effectively used as a cement raw material.

  In the above configuration, preferably, the method further includes a step of cooling the exhaust gas generated by the incineration step before the first step.

  According to the said structure, since the fly ash contained in the waste gas cooled at the process to cool can be collect | recovered at a 1st process, it becomes easy to collect | recover fly ash with much content of a chlorine component at a 1st process. By collecting fly ash with a high chlorine component content in the first step, the chlorine component content of the exhaust gas supplied to the overheating step is reduced, so the superheater used in the overheating step is a molten salt by the chlorine component. Corrosion can be suppressed.

  In the above configuration, preferably, the first step is a step of collecting fly ash contained in exhaust gas at 600 ° C. or higher.

  By collecting fly ash contained in the exhaust gas at 600 ° C. or higher in the first step, it is possible to supply high temperature exhaust gas that is unlikely to cause corrosion to the superheater. Thereby, it is possible to suppress the occurrence of molten salt corrosion in the superheater and to set the superheated steam flowing in the superheater to 400 ° C. or higher.

  ADVANTAGE OF THE INVENTION According to this invention, the waste processing equipment and waste processing method which a superheater cannot corrode easily can be provided.

It is the schematic which shows the whole structure of the waste disposal facility which concerns on embodiment of this invention. It is the graph obtained by simulating with thermodynamic equilibrium calculation software the temperature of exhaust gas, and the production amount (mol) of each component in the fly ash (condensed phase) contained in the exhaust gas at that temperature.

  A preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of a waste treatment facility 10 according to an embodiment of the present invention. First, the processing point of the waste 11 in the waste processing facility 10 will be described.

  As shown in FIG. 1, the waste treatment facility 10 of the present embodiment includes a waste pit 1, a dust feeder 2, an incinerator 3, a second recovery unit 52, a cooling mechanism 51, in order from the upstream side. The first recovery unit 53, the superheater 54, the temperature reducing tower 6, the bag filter 7, the denitration device 8, and the chimney 9 are provided. In this waste treatment facility 10, first, waste stored in the garbage pit 1 is put into the dust feeder 2, and quantitatively supplied from the dust feeder 2 to the incinerator 3. By incinerating waste in the incinerator 3, exhaust gas is generated. Due to the high temperature combustion in the incinerator 3, exhaust gas of 800 ° C. or higher and 1000 ° C. or lower is discharged. This exhaust gas is introduced into the second recovery unit 52, and fly ash contained in the exhaust gas is recovered by the second recovery unit 52. Thereafter, exhaust gas is supplied to the cooling mechanism 51, and the exhaust gas is cooled by the cooling mechanism 51, whereby fly ash contained in the exhaust gas is further precipitated. The fly ash deposited here is collected by the first collection unit 53. Thereafter, the exhaust gas is supplied to the superheater 54, and after the waste heat is recovered by the superheater 54, it is cooled by the temperature reducing tower 6. The heat recovered by the superheater 54 is used for steam superheating. The superheated steam superheated by the superheater 54 is used, for example, for starting a turbine (not shown) and contributes to power generation. As a model case, for example, the temperatures of the exhaust gas immediately before passing through the second recovery unit 52, the cooling mechanism 51, the first recovery unit 53, and the superheater 54 are 1000 ° C., 850 ° C., 690 ° C., and 600 ° C., respectively. The installation positions of the cooling mechanism 51 and the second recovery unit 52 are merely examples, and the order may be reversed. The exhaust gas cooled by the temperature reducing tower 6 is dedusted by the bag filter 7 and discharged from the chimney 9 through the denitration device 8.

  The incinerator 3 includes a gasification furnace that generates pyrolysis gas by pyrolyzing (gasifying) waste, and a melting furnace that generates exhaust gas by burning the pyrolysis gas generated in the gasification furnace. And may be configured.

  The waste 11 used in the waste treatment facility 10 of this embodiment is preferably municipal waste. Municipal waste is a low-calorie waste with a relatively low calorific value. In general, municipal waste is subject to large fluctuations in its properties, so the calorific value of the generated combustible gas tends to fluctuate. Waste plastic that does not vary in character compared to municipal waste may be mixed and used. Thereby, the calorific value of the combustible gas produced | generated can be made hard to fluctuate. The processing target is not limited to municipal waste, and various types of general waste, industrial waste, and the like may be processed. In addition to waste plastic, dehydrated sludge, waste tires, waste paper, rubber, waste oil, waste oil sludge, woody biomass, and the like may be used as high-heat waste to be mixed with municipal waste.

  The second recovery unit 52 recovers fly ash contained in the exhaust gas at 800 ° C. or higher and 1000 ° C. or lower. For example, a heat-resistant ceramic filter or cyclone can be used. Since the chlorine component is in a gaseous state in the exhaust gas at 800 ° C. or higher and 1000 ° C. or lower, the fly ash recovered by the second recovery unit 52 has a low chlorine component content and is effectively used as a cement raw material. can do.

  The cooling mechanism 51 cools the exhaust gas that has passed through the second recovery part 52. As the exhaust gas passes through the cooling mechanism 51, the heat of the exhaust gas is deprived and the temperature of the exhaust gas decreases, and the chlorine component contained in the exhaust gas is deposited as the temperature of the exhaust gas decreases. By cooling the exhaust gas that has passed through the second recovery unit 52 to below 700 ° C. with the cooling mechanism 51, the chlorine component in the exhaust gas is precipitated as fly ash, and the fly ash is recovered by the subsequent first recovery unit 53. Can do.

  As the cooling mechanism 51, it is more preferable to use an evaporator. The evaporator generates water to be boiled by heat exchange between the exhaust gas generated in the incinerator 3 and water and supplies steam to the superheater 54, and cools the exhaust gas. The evaporator is provided with a heat transfer tube having a cavity for allowing water and steam to pass therethrough, and the water flowing in the heat transfer tube is heated by the heat of the exhaust gas to become steam. This steam is sent to the superheater 54.

  Although the exhaust gas that passes through the evaporator is hotter than the exhaust gas that passes through the superheater 54, the heat of the exhaust gas in contact with the evaporator is used for the heat of vaporization of the water flowing inside the evaporator, so the evaporator itself Is less likely to be higher than 100 ° C., which is the boiling point of water. Moreover, since the exhaust gas at the time of passing through the evaporator is over 800 ° C., the chlorine component in the exhaust gas is difficult to deposit, and even if it deposits on the surface of the evaporator, the deposit becomes an exhaust gas exceeding 800 ° C. It is easy to be vaporized again after being exposed. In this way, the evaporator itself does not reach a very high temperature, and the chlorine component hardly deposits on the surface of the evaporator, so that molten salt corrosion of the evaporator hardly occurs.

  As the cooling mechanism 51, in addition to the evaporator, a water-cooled wall or a boiler radiation heat transfer surface can be used alone or in combination with an evaporator. The water-cooled wall has an inner wall and an outer wall that is spaced apart from the inner wall, and boiles the water by exchanging heat between the water that flows between the inner wall and the outer wall and the exhaust gas that contacts the inner wall. Steam is generated and exhaust gas is cooled. The steam generated in the water cooling wall is sent to the superheater 54.

  The boiler radiant heat transfer surface has a channel through which water or the like passes and is made of a material that absorbs the radiant heat of the exhaust gas. The radiant heat of the exhaust gas can boil water in the flow path to generate steam and cool the exhaust gas. The steam generated on the boiler radiation heat transfer surface is sent to the superheater 54.

  The first recovery unit 53 recovers fly ash contained in the exhaust gas of less than 700 ° C. after being cooled by the cooling mechanism 51, and is similar to the various dust collectors exemplified in the second recovery unit 52. Things can be used. Since the first recovery unit 53 is provided on the downstream side of the cooling mechanism 51, the fly ash contained in the exhaust gas after being cooled by the cooling mechanism 51 can be recovered. As described above, fly ash containing a large amount of chlorine component is recovered by the first recovery unit 53, thereby reducing the chlorine component content of the exhaust gas supplied to the superheater 54, and thus the molten salt of the superheater 54. Thinning due to corrosion can be suppressed.

  It is preferable that the 1st collection | recovery part 53 collect | recovers the fly ash contained in the waste gas of 600 degreeC or more. By setting the exhaust gas passing through the first recovery part 53 to 600 ° C. or higher, high-temperature exhaust gas that is unlikely to be corroded can be supplied to the superheater 54. Thereby, molten salt corrosion hardly occurs in the superheater 54, and the superheated steam flowing in the superheater 54 can be set to 400 ° C. or higher.

Here, the simulation result of the relationship between the temperature of exhaust gas and the weight of each component of fly ash contained in the exhaust gas at that temperature will be described. FIG. 2 is a graph obtained by simulating the temperature of exhaust gas and the generation amount (mol) of each component of fly ash (condensed phase) contained in the exhaust gas at that temperature with thermodynamic equilibrium calculation software, The relationship between the temperature of exhaust gas and the production amount (mol) of each component of fly ash contained in 1 m ³ of exhaust gas at that temperature is shown. The horizontal axis in FIG. 2 is the exhaust gas temperature (° C.), and the vertical axis is the production amount (mol) of each component.

Fly ash contains each composition shown in the column of the item of FIG. 2 as a main component, specifically, potassium chloride (KCl), sodium chloride (NaCl), calcium carbonate (CaCO ₃ ), calcium sulfate ( CaSO ₄ ), calcium chloride (CaCl ₂ ), chromium oxide (Cr ₂ O ₃ ), iron oxide (Fe ₂ O ₃ ), potassium sulfide (K ₂ SO ₄ ), sodium sulfide (Na ₂ SO ₄ ), etc. In the eutectic state.

Since the phase transition point from gas to liquid or solid is different depending on each composition shown in FIG. 2, the proportion of each component contained in the fly ash varies depending on the temperature of the exhaust gas as shown in FIG. As a general tendency of fly ash, as the temperature of exhaust gas becomes lower, each component becomes liquid or solid and becomes easier to collect as fly ash. For example, as shown in the graph of FIG. 2, the fly ash in 1 m ³ of exhaust gas at 1000 ° C. contains about 0.011 mol of CaSO ₄ and 0.0018 mol of Fe ₂ O ₃ , whereas the exhaust gas at 600 ° C. Fly ash in 1 m ³ is about 0.011 mol NaCl, 0.011 mol CaSO ₄ , 0.006 mol Fe ₂ O ₃ , 0.006 mol KCl, 0.0043 mol CaCO ₃ , and Containing 0.0043 mol of CaCl ₂ .

  Paying attention to the chlorine component in the graph of FIG. 2, as the temperature of the exhaust gas becomes higher than 700 ° C., the ratio of the chlorine component (KCl, NaCl) in the fly ash gradually decreases and is recovered from the exhaust gas at 800 ° C. or higher. It is understood that fly ash contains almost no chlorine component. On the contrary, when the temperature of the exhaust gas is less than 700 ° C., almost all of the chlorine components are precipitated in a liquid or solid state, and thus the chlorine component in the exhaust gas is efficiently recovered by recovering fly ash from the exhaust gas of less than 700 ° C. It becomes possible.

  In the waste treatment facility 10 of the present embodiment, the installation positions of the first and second recovery units 53 and 52 are determined based on the simulation result of FIG. That is, the 2nd recovery part 52 is provided in the position where the exhaust gas of 800 ° C or more and 1000 ° C or less passes, and the 1st recovery part 53 is provided in the position where the exhaust gas of less than 700 ° C passes. By installing the first and second recovery units 53 and 52 at such positions, the second recovery unit 52 can recover fly ash with a low content of chlorine components, and the subsequent first recovery unit In 53, fly ash containing a large amount of chlorine component can be recovered. The fly ash recovered by the second recovery unit 53 can be effectively used as a raw material for cement or the like without performing post-treatment because the weight ratio of chlorine to the entire fly ash is 1% by mass or less. Further, since the concentration of the chlorine component in the exhaust gas that has passed through the first recovery unit 53 is low, it is possible to suppress the superheater 54 described later from being exposed to the chlorine component, and to suppress the molten salt corrosion of the superheater 54. It becomes possible.

  The superheater 54 cools the exhaust gas by exchanging heat between the exhaust gas and the steam, and further superheats the steam. In the superheater 54, the steam exceeding 100 ° C. is further superheated to become superheated steam of 300 ° C. or more and 600 ° C. or less, and the superheated steam is supplied to a turbine (not shown) to generate electric power. The pressure of the superheated steam is, for example, 40 bar or more and 60 bar or less. Since the superheater 54 superheats the steam flowing inside, the superheater 54 tends to have a higher temperature than the evaporator that evaporates the water flowing inside. For this reason, if a chlorine component adheres to the surface of the superheater 54, the surface of the superheater 54 is liable to cause molten salt corrosion, but in this embodiment, the fly ash containing the chlorine component is exhausted before the exhaust gas reaches the superheater 54. Since the recovery is performed by the one recovery unit 53, it is possible to suppress the precipitation of chlorine components on the surface of the superheater 54, and it is possible to suppress the molten salt corrosion of the superheater 54. For this reason, the temperature of the exhaust gas supplied to the superheater 54 can be further increased, and the temperature of the superheated steam obtained by the superheater 54 can be increased. By using an evaporator as the cooling mechanism 51, the heat of the exhaust gas cooled by the cooling mechanism 51 can be used to evaporate water, and by supplying the steam generated by the evaporator to the superheater 54 The heat of exhaust gas can be used effectively.

<Waste treatment method>
In the waste treatment method using the waste treatment facility 10 of the above embodiment, first, as shown in FIG. 1, the waste 11 in the garbage pit 1 is thrown into the dust feeder 2 and the dust feeder 2 is concerned. Is quantitatively supplied to the incinerator 3. Exhaust gas is discharged by incinerating the waste 11 in the incinerator 3 (incineration process). A swirl flow is formed in the incinerator 3, and, for example, exhaust gas at 800 ° C. to 1000 ° C. is second recovered by performing high-temperature combustion at about 1000 ° C. under conditions of a total air ratio of 1.3 to 1.5. It is discharged to the part 52. In the waste treatment facility 10 of the present embodiment, the high temperature exhaust gas is taken out by directly incinerating the waste, but the pyrolysis gas is taken out by pyrolyzing the waste, and the pyrolysis gas is incinerated. The exhaust gas may be taken out by doing so.

  Next, the fly ash contained in the exhaust gas at 800 ° C. or higher is recovered by the second recovery unit 52 (second step). When the temperature of the exhaust gas is 800 ° C. or higher, almost all of the chlorine component contained in the exhaust gas is a gas. Therefore, in the second recovery unit 52, the weight ratio of chlorine to the entire fly ash is 1% by mass or less. can do. The fly ash collected in the second step can be used as a cement raw material without post-treatment.

  Next, fly ash contained in the exhaust gas of less than 700 ° C. is recovered by the first recovery unit 53 (first step). Since the exhaust gas that passes through the first recovery part 53 is less than 700 ° C., the chlorine component contained in the exhaust gas becomes liquid or solid and is deposited as fly ash. For this reason, the first recovery unit 53 can recover fly ash containing a large amount of chlorine components.

  Finally, in the superheater 54, the exhaust gas that has passed through the first recovery unit 53 and the steam are subjected to heat exchange to cool the exhaust gas and superheat the steam to form superheated steam. Thus, by heating the steam with the superheater 54, high-temperature superheated steam that does not corrode the superheater 54 can be obtained, and the power generation efficiency of the turbine supplied with the superheated steam can be increased.

  Further, since fly ash containing a large amount of chlorine component is recovered by the first recovery unit 53, the chlorine component content of the exhaust gas supplied to the superheater 54 can be reduced. That is, high-temperature exhaust gas that is unlikely to corrode can be supplied to the superheater 54. Thereby, it is possible to suppress the superheater 54 from being subjected to molten salt corrosion by the chlorine component, and the superheated steam flowing in the superheater 54 can be set to 400 ° C. or higher.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to this Example. In this example, the waste 11 was treated using the waste treatment facility 10 shown in FIG. Further, an evaporator was used as the cooling mechanism 51 in FIG. First, the waste 11 stored in the garbage pit 1 was put into the dust feeder 2 and quantitatively supplied from the dust feeder 2 to the incinerator 3. And the waste gas was burned in this incinerator 3, and about 800-1000 degreeC exhaust gas was generated.

The fly ash contained in the exhaust gas was recovered by passing the exhaust gas through the ceramic filter (second recovery part 52). The second recovery unit 52 was able to recover 1.70 g of fly ash for 1 m ³ of exhaust gas at 833 ° C. When the weight ratio of chlorine contained in the fly ash was measured by ion chromatography, the mass ratio of chlorine was 0.50% by mass.

Next, the exhaust gas that passed through the second recovery unit 52 was supplied to the evaporator that is the cooling mechanism 51. The heat of the exhaust gas was gradually taken away by this evaporator, and the temperature of the exhaust gas after passing through the evaporator was 639 ° C. The heat recovered by the evaporator boiled water flowing through the evaporator to generate steam. The steam generated here was passed through the superheater 54. By collecting this exhaust gas from the nozzle (first recovery unit 53), fly ash contained in the exhaust gas at 639 ° C. was recovered. The first recovery unit 53 recovered 4.29 g of fly ash for 1 m ³ of exhaust gas at 639 ° C. When the mass% of chlorine contained in the fly ash was measured by an ion chromatography method, the mass ratio of the chlorine was 6.39 mass%.

  Finally, the superheated steam at about 580 ° C., which is higher than the conventional 400 ° C., can be obtained by superheating the steam flowing in the superheater 54 using the exhaust gas that has passed through the first recovery part 53. By generating electric power by supplying this superheated steam to the turbine, it was possible to improve the power generation efficiency. The exhaust gas was cooled by the temperature reducing tower 6, removed by the bag filter 7, and discharged from the chimney 9 through the denitration device 8.

  According to the present embodiment, the exhaust gas having a temperature of less than 700 ° C. is allowed to pass through the first recovery unit 53, whereby fly ash containing a large amount of chlorine components can be recovered by the first recovery unit 53. It was clarified that the chlorine component can be prevented from adhering to the superheater and the molten salt corrosion of the superheater 54 can be suppressed, and the effect of the present invention was shown. As a result, it has become clear that the temperature of the exhaust gas that can be supplied to the superheater 54 can be increased, and higher-temperature superheated steam can be obtained.

  Moreover, according to the said Example, it also becomes clear that the fly ash whose mass ratio of chlorine is 1 mass% or less can be collect | recovered by passing the exhaust gas 800 degreeC or more and 1000 degrees C or less to the 2nd collection | recovery part 52. It was. The fly ash collected here can be effectively used as a cement raw material without post-treatment.

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Garbage pit 2 Dust feeder 3 Incinerator 6 Temperature reduction tower 7 Bag filter 8 Denitration device 9 Chimney 10 Waste disposal equipment 11 Waste 51 Cooling mechanism 52 2nd collection part 53 1st collection part 54 Superheater

Claims (9)

An incinerator for incinerating waste or combustible gas generated from the waste;
A superheater that cools the exhaust gas by heat-exchanging the exhaust gas and steam generated in the incinerator and superheats the steam;
A waste treatment facility comprising: a first recovery unit that recovers fly ash contained in exhaust gas of less than 700 ° C. from a position between the incinerator and the superheater.   The waste treatment facility according to claim 1, further comprising a second recovery unit that recovers fly ash contained in the exhaust gas at 800 ° C or higher from a position between the incinerator and the first recovery unit. A cooling mechanism for cooling the exhaust gas generated in the incinerator;
3. The cooling mechanism according to claim 1, wherein the cooling mechanism is provided between the incinerator and the first recovery unit so that the exhaust gas supplied to the first recovery unit is cooled to less than 700 ° C. 4. Waste treatment facility.   4. The evaporator according to claim 3, wherein the cooling mechanism is an evaporator for boiling the water by heat exchange between the exhaust gas generated in the incinerator and water to generate steam supplied to the superheater and cooling the exhaust gas. The listed waste treatment facility.   The waste treatment facility according to any one of claims 1 to 3, wherein the first recovery unit recovers fly ash contained in exhaust gas at 600 ° C or higher. Incineration of waste or combustible gas generated from the waste; and
Cooling the exhaust gas by heat-exchanging the exhaust gas and steam generated by the incineration step, and superheating the steam;
And a first step of collecting fly ash contained in the exhaust gas of less than 700 ° C. before the overheating step.   The waste treatment method according to claim 6, further comprising a second step of collecting fly ash contained in the exhaust gas at 800 ° C. or higher before the first step.   The waste disposal method according to claim 6 or 7, further comprising a step of cooling the exhaust gas generated by the incineration step before the first step.   The waste treatment method according to any one of claims 6 to 8, wherein the first step is a step of collecting fly ash contained in exhaust gas at 600 ° C or higher.

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