JPH11262741A - Method and apparatus for treating waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dehydrate a waste slurry containing vinyl chloride and other chlorine resin after hydrothermal decomposition reaction to convert the same to a cake used as fuel and electrolyzing a filtrate to circulate the same to a reaction system as an alkali soln. to use the same. SOLUTION: Solid waste containing a large amt. of vinyl chloride and other chlorine resin is pretreated by a pretreatment means 10 to form a waste slurry which is, in turn, subjected to hydrothermal reaction by a reactor 14 to obtain a reaction raw slurry and this slurry is succeedingly dehydrated in succession to flashing to obtain cake-like dechlorinated raw fuel and a filtrate. The filtrate is electrolyzed to be recovered and circulated as an alkali aq. soln. and this soln. is supplied to the pretreatment means 10 as the neutralizing agent of the waste slurry.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to dewatering of organic solids such as municipal solid waste and industrial wastes, especially waste slurries containing a large amount of vinyl chloride and other chlorine-containing resins, after a hydrothermal decomposition reaction. The present invention relates to a method and an apparatus for treating waste, in which the cake is converted into a fuel and the filtrate is electrolytically treated to be circulated and used as an aqueous alkaline solution.

[0002]

2. Description of the Related Art Solid waste such as general waste such as municipal solid waste and industrial waste discharged from factories and the like is increasing year by year. I have. From such a point of view, after crushing solid waste in water and recovering useful materials such as iron, aluminum and glass that can be recycled in the form of a water slurry,
Dehydrate to a state having an appropriate moisture value, and then subject the high-temperature and high-pressure reaction slurry obtained by the hydrothermal reaction to a predetermined residence time under high-temperature and high-pressure conditions, and finally reduce the pressure to atmospheric pressure. To obtain the product slurry.

[0003]

However, when treating municipal waste or industrial waste containing a large amount of vinyl chloride or other chlorine-containing resin, there are the following problems. When municipal solid waste or industrial waste containing a large amount of vinyl chloride or other chlorine-containing resin is incinerated, dioxin, which is a highly toxic substance, may be generated, which poses a problem from the viewpoint of environmental protection. Further, when burning waste containing a large amount of vinyl chloride or other chlorine-containing resin, Cl ₂ or HCl is generated during the combustion, and corrosion problems are likely to occur in a subsequent air preheater, a waste heat recovery boiler, or the like. Waste containing organic chlorine compounds can be dechlorinated by hydrothermal reaction, but the resulting hydrochloric acid and alkali salts (sodium chloride) are highly corrosive and have a limited solubility. Must be discharged outside the system so that it does not accumulate. COD for draining the filtrate into public waters as wastewater
(Chemical oxygen demand) Wastewater treatment equipment mainly for removal and treatment costs are required, and thus the costs are high. Further, in the method of crystallizing and separating sodium chloride in the filtrate by evaporation and concentration, a large amount of heat energy is required because most of the water is evaporated.

[0004] The present invention has been made in view of the above problems, and an object of the present invention is to slurry a waste containing a large amount of vinyl chloride or other chlorine-containing resin, and then to dehydrate after a hydrothermal decomposition reaction. It is an object of the present invention to provide a method and an apparatus for treating waste, wherein the cake is converted into a raw material fuel and the filtrate is electrolytically treated to be recycled as an aqueous alkaline solution to a reaction system.

[0005]

In order to achieve the above object, according to a first aspect of the present invention, a solid waste containing a large amount of vinyl chloride or other chlorine-containing resin is treated by a pretreatment means. The slurry is subjected to hydrothermal reaction in a reactor to obtain a reaction product slurry, which is then dewatered after flashing to obtain a cake-like dechlorinated raw fuel and a filtrate. In the treatment method, the filtrate is electrolytically treated to recover and circulate as an aqueous alkaline solution. In the second invention mainly based on the first invention,
Chlorine gas and hydrogen gas generated when the filtrate is subjected to electrolytic treatment are taken out of the system, and the remaining alkaline aqueous solution is circulated and used as a neutralizing agent for the waste slurry. In the third invention, the cake-like fuel after the dechlorination is burned in a combustion furnace, a heat medium is heated by combustion heat at the time of the combustion, and the heat medium is disposed on a path leading to a reactor. The waste slurry was heated through a heat exchanger.

[0006] In a fourth invention mainly based on the first invention,
The steam generated at the time of the flash is passed through a heat exchanger disposed in a path leading to the reactor to be used for heating the waste slurry, and a condensate discharged from the heat exchanger after the heat exchange is dewatered by the reaction slurry. In the fifth aspect of the invention, which is mainly based on the fourth aspect, the condensate is circulated and used in the system as washing water for dehydrating the reaction slurry. When the condensate runs short, make-up water is supplied from the outside.

[0007] In a sixth invention mainly based on the first invention,
The filtrate was electrolytically treated by an ion exchange membrane method or a diaphragm method, and the alkaline aqueous solution obtained by the electrolytic treatment was circulated. In a seventh aspect of the invention, which is based on the first aspect, the filtrate is subjected to electrolytic treatment by an ion exchange membrane method or a diaphragm method having an anode and a cathode to generate chlorine gas from the anode and hydrogen gas from the cathode. After that, the decomposed solution after electrolysis was circulated and used as an aqueous alkali solution.

[0008] In the eighth invention, solid waste containing a large amount of vinyl chloride or other chlorine-containing resin is converted into a waste slurry by a pretreatment means, and the slurry is hydrothermally reacted in a reactor to form a reaction slurry. After obtaining, a waste treatment apparatus in which dewatering is performed after flash to obtain cake-like dechlorinated raw fuel and a filtrate, and an electrolytic means capable of electrolytically treating the filtrate is provided, In a ninth invention mainly based on the eighth invention, the electrolysis means is an electrolysis means using an ion exchange membrane method or a diaphragm method having an anode and a cathode, respectively.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the method and apparatus for treating waste according to the present invention will be described with reference to FIGS.
This will be described in detail with reference to FIG.

FIG. 1 is a block diagram of a system configuration according to an embodiment of the present invention. FIG. 2 is a system block diagram in which a filtrate is subjected to electrolytic treatment using an electrolytic device using an ion exchange membrane. FIG. 3 uses an electrolytic device using a diaphragm. FIG. 4 is a system block diagram of an embodiment in which a small amount of vinyl chloride is contained in solid waste, FIG. 5 is a system block diagram of a second case, and FIG. FIG. 9 is a system block diagram of a third case.

FIG. 1 will be described in detail below. First, wastes containing organic solids that have been collected from various places and that are in an unsorted state are pretreated, and then supplied to the thermal decomposition process. In particular, in the present invention, waste containing a large amount of vinyl chloride and other chlorine-containing resins is supplied to the pretreatment step.

In the pretreatment step, when treating wastes containing a large amount of vinyl chloride and other chlorine-containing resins which are basically unsorted, useful materials such as iron, aluminum and glass which can be recycled are treated. Therefore, it is necessary to first recover the solid waste and slurry the solid waste to such an extent that the solid waste can be transported for continuous operation of the solid waste treatment system. Pre-processing means 10 for this is provided,
The pretreatment means 10 includes a crushing device, a separation device for useful materials, a dewatering device, and the like.

Therefore, in the pretreatment means 10, solid waste containing organic solid matter in an unsorted state is made into a water slurry by crushing in water, and in this slurrying step, non-combustible substances contained in the crushed material are formed. By utilizing the difference in specific gravity of materials, useful materials such as recyclable iron, aluminum, and glass are collected. Then, the water slurry containing the organic solid matter from which the incombustible matter has been removed is dehydrated to a solid matter content of about 8 to 20% by weight, and is adjusted to have a viscosity enough to be conveyed to the subsequent processing step. I have.

The waste slurry treated by the pretreatment means 10 is temporarily stored in a storage tank 12, where the waste slurry forms a buffer between the treatment by the pretreatment means 10 and the subsequent treatment step. The waste slurry discharged from the storage tank 12 contains an alkaline aqueous solution 2
8 has been added. The waste slurry in the storage tank 12 is supplied to the subsequent reactor 14 as a waste slurry mixed with a base by a pumping means such as a high-pressure pump 13 so that the hydrothermal reaction is performed while flowing through the reactor 14. Is caused.

The operating temperature in the reactor 14 is from 250 to 350
The temperature is raised to an appropriate temperature of about
The slurry is fed while being pressurized to about 170 atm by step 3, and the temperature is raised in advance to the reaction temperature before the reactor 14. In the embodiment, the first heat exchanger 16 and the second heat exchanger are used. The temperature is raised stepwise to the reaction temperature at 18 before being fed to the reactor 14. As a result, the waste slurry whose temperature has been raised passes through the reactor 14 while maintaining the reaction temperature and at a pressure higher than the saturated steam pressure of the reaction temperature for a reaction time of several minutes to tens of minutes. Is thermally decomposed by a hydrothermal reaction.

In the present embodiment, the reaction slurry after the hydrothermal reaction in the reactor 14 uses a flash evaporator 20 as a cooling device and supplies steam generated by flash evaporation to the first heat exchanger 16. ing. That is, the temperature is raised stepwise to the reaction temperature, and then sent to the reactor 14, a hydrothermal reaction is performed under predetermined operating conditions, and steam flashed by isenthalpy expansion using the flash evaporator 20 is used. It is supposed to. In order to increase the efficiency of such heat recovery, it is desirable to reduce the flash pressure in several stages. Further, by compressing the flash steam (for example, by heat pump), the efficiency of heat recovery can be further improved.

Further, the reaction slurry from the reactor 14 is flushed to a flash evaporator 20 and reduced in pressure to the atmospheric pressure. At this time, steam is generated. In the process of concentrating the reaction slurry stored in the flash evaporator 20 by a centrifugal separator or the like constituting the separation means 24, a filtrate 29 containing dissolved gas, salt, and the like, and a dechlorinated fuel cake 27 are obtained. The product cake 27 is burned in the heating medium heating furnace 34, and the heat medium circulating between the first heat exchanger 18 and the heating medium heating furnace 34 is heated by the combustion heat. Since the flash steam after heating the waste slurry mixed with the base in the first heat exchanger 16 is condensed, the condensate is used as a washing liquid for the fuel cake 27 obtained by separation by the separation means 24. Is done.

The fuel cake 2 is washed by condensed liquid.
7. The mother liquor containing chloride ions in 7 is replaced with a condensate,
A fuel cake 27 containing a dechlorinated combustible water concentration of 20 to 60% by weight is obtained. The condensed liquid is used as a cleaning liquid for the fuel cake 27. In consideration of the case where the condensed liquid alone is insufficient as the cleaning liquid, a flash steam condensing line connected from the first heat exchanger 16 to the separating means 24 is taken into consideration. It is desirable to provide a supply line for makeup water in the middle of the process.

The slurry of the waste is hydrothermally reacted in the reactor 14, and the obtained reaction slurry is separated by the separating means 24 to obtain the fuel cake 27 and the filtrate 29. Among them, municipal solid waste and industrial waste ( In particular, when the proportion of the chlorine-based resin contained in the waste (the waste material used as the raw material for this treatment) is large, the filtrate 29
Is supplied to the electrolytic means 26 (see FIG. 1). Also,
When the ratio of the amount of chlorine-based resin contained in municipal solid waste or industrial waste (particularly, waste as raw material for the main treatment) is small, a part of the filtrate 29 (X in FIG. , And the remaining filtrate 29 (Y in FIG. 4) is circulated directly as water for slurry adjustment in the pretreatment step without being supplied to the electrolytic means 26. A case where the entire filtrate 29 is fed to the electrolytic means 26 will be described with reference to FIG. The filtrate 29 is decomposed into chlorine gas, hydrogen gas and an aqueous alkaline solution 28 by electrolytic treatment. As such electrolysis means 26, for example, an electrolysis method using an ion exchange membrane method or an electrolysis method using a diaphragm method can be considered.

First, an electrolytic apparatus using an ion exchange membrane will be described with reference to FIG. Reference numeral 36 denotes an electrolyzer, which comprises an ion exchange membrane 38, an anode 40 and a cathode 42, and is arranged in parallel with each other. An ion exchange membrane 38 is stretched from one end of the electrolysis device 36 to the other end so as to divide the electrolysis device 36 into two parts. The filtrate 29 is supplied to the electrolysis device 36.
A return pipe 44 having a U-shape communicating the anode chamber 46 and the cathode chamber 48 is provided at the other end opposite to the inlet to be introduced.
Is arranged.

An anode 40 is provided in the anode chamber 46 communicating with the inlet of the filtrate 29 along the longitudinal direction of the anode chamber 46. When the filtrate 29 flows, chlorine gas is generated by an electrode reaction. I have. A cathode 42 is provided along the longitudinal direction of the cathode chamber 48 in the cathode chamber 48 having an outlet for the alkaline aqueous solution 28 generated after one electrolysis, and when the filtrate 29 flows, hydrogen gas is generated by an electrode reaction. It has become. On the other hand, as the ion exchange membrane 38, a cation-based one is usually used. After a chlorine gas is generated from the anode 40, alkali metal ions such as Na move to the cathode chamber 48 through the ion exchange membrane 38. As a result, sodium hydroxide (NaOH) is generated, and finally, the filtrate 29 is electrolyzed to become an alkaline aqueous solution 28 which is a decomposition solution. Note that, as described above, the alkali metal is not limited to the example of Na, and similar results can be obtained with K, for example.

As described above, the case where a cationic type is used as the ion exchange membrane 38 has been described. However, the present invention is not limited to the cationic type, and an anionic type may be used. When an anionic material is used, the filtrate 29 is supplied to the cathode chamber 48, unlike the case where the filtrate 29 is supplied to the anode chamber 46 as in the case of a cation type. The filtrate 29 supplied to the cathode chamber 48 generates hydrogen gas by an electrode reaction and generates chlorine gas from the anode 40, and then anions such as OH ⁻ (hydroxyl ions) pass through the ion exchange membrane 38. By moving to the anode chamber 46, sodium hydroxide (NaOH) is generated, and finally, the filtrate 29 undergoes an electrode reaction to become an alkaline aqueous solution 28 which is a decomposition solution.

Next, an electrolyzer using a diaphragm method will be described with reference to FIG. Reference numeral 50 denotes an electrolysis device, which is composed of a diaphragm 52 made of unglazed or asbestos, an anode 54 and a cathode 56, and is arranged in parallel. Electrolysis device 5 from one end to the other end of electrolysis device 50
The diaphragm 52 is stretched so as to divide 0 into two, and is divided into two to form an anode chamber 58 and a cathode chamber 60. Further, the anode chamber 58 constituting the electrolysis apparatus 50 has an inlet for the filtrate 29 at one end thereof, and the cathode chamber 60 has an outlet for the alkaline aqueous solution 28 on the side opposite to the inlet.

An anode 54 is provided along the longitudinal direction of the anode chamber 58 in the anode chamber 58 communicating with the inlet of the filtrate 29. When the filtrate 29 flows, chlorine gas is generated by an electrode reaction. I have. A cathode 56 is disposed along the longitudinal direction of the cathode chamber 60 having an outlet for the alkaline aqueous solution 28 generated after one electrolysis. On the other hand, with respect to the diaphragm 52, the filtrate 29 which has been introduced from the inlet and subjected to an electrode reaction at the anode 54 passes through the diaphragm 52, and subsequently moves to the cathode chamber 60, where hydrogen gas is generated by the electrode reaction and hydrogen ions are removed. Alkaline solution 2
8, and is discharged from the outlet of the cathode chamber 60.

Incidentally, raw material waste such as municipal waste contains a large amount of vinyl chloride and other chlorine-containing resins, and the chlorine compound generates hydrogen chloride upon thermal decomposition. For this reason, as described later, a slurry of waste to which a base has been added is formed, and the slurry obtained by hydrothermally reacting the slurry in the reactor 14 is separated by the separating means 24 to form a cake 27 and a filtrate 29. However, when the filtrate 29 is fed to the electrolysis means 26 and electrolyzed, the filtrate 29 is separated into chlorine gas, hydrogen gas and an aqueous alkaline solution 28. The alkaline aqueous solution 28 is temporarily stored in an alkaline aqueous solution tank 30 and neutralizes hydrogen chloride generated during the hydrothermal reaction by adding the alkaline aqueous solution 28 to the waste slurry subjected to the hydrothermal reaction.

An alkaline aqueous solution 28 which is an alkaline substance
Is added for the purpose of preventing corrosion of liquid-contacting parts such as reactors, heat exchangers, and other piping due to generation of hydrochloric acid and the like by the reaction. Alkaline aqueous solution tank 30
The alkaline substance supplied through the alkaline aqueous solution supply pump 32 is continuously injected, and the injection amount is an amount necessary for neutralizing the generated hydrogen chloride. It is necessary to increase the alkali concentration or the addition amount of the alkaline aqueous solution 28 according to the content.

The alkali concentration of the alkaline aqueous solution 28 is controlled by the amount of electric current for electrolysis. The injection position is such that when the amount of the solution is large, it is supplied to the pretreatment step as water forming a slurry, but when the amount is small, May be injected directly downstream of the storage tank 12 between the pretreatment or storage tank 12 and the high-pressure pump 13 or supplied directly to the storage tank 12. The alkaline aqueous solution supply pump 32 is a variable pump that can be adjusted according to the pH value of the reaction product.

The specific contents of a treatment method using such a waste treatment system will be described.

A so-called solid waste containing a large amount of vinyl chloride or other chlorine-containing resin in an organic solid such as municipal solid waste or industrial waste is introduced into a treatment system in a mixed unsorted state. The unsorted waste is mixed with the alkaline aqueous solution 28 or the filtrate 29 in the first pretreatment means 10, and
The slurry is pulverized to form an aqueous slurry, from which useful inorganic substances such as iron and aluminum are separated to produce a waste slurry containing organic solids.

In the pulverization process, several m of solid matter is obtained by crushing in water.
m, so that an aqueous slurry is obtained, and iron and the like are separated and removed during crushing in water. Next, this aqueous slurry is put into a cyclone,
Here, a useful material such as aluminum or glass is separated, and a slurry containing an organic solid is adjusted so as to increase the solid concentration (about 14% by weight) within a range that can be pumped through a dehydrator, and the storage tank is adjusted. Put into 12. The waste slurry having been subjected to the pretreatment is sent to the reactor 14 by the high-pressure pump 13.

In the present invention, solid waste is allowed to contain a large amount of an organic chlorine-based resin such as vinyl chloride which generates hydrogen chloride upon thermal decomposition. Hydrogen chloride generated in the reactor 14 is an alkaline aqueous solution 28 as an alkaline substance.
To perform a neutralization treatment.

The alkaline aqueous solution 28 is supplied to the reactor 1
The pH of the reaction product slurry at the outlet of No. 4 is slightly acidic pH =
The amount of addition (alkaline concentration in alkaline water) may be adjusted so as to be 3 to 6, preferably 4 to 6. As described above, by controlling the electrolytic current so that the pH of the reaction product slurry at the outlet of the reactor 14 becomes weakly acidic, continuous operation of the treatment of the composite waste becomes possible. Further, by detecting the outlet pH of the reactor 14 and adjusting the alkali concentration and the addition amount of the alkali aqueous solution so as to maintain the pH at a predetermined value, the amount of vinyl chloride or other chlorine-containing resin in the solid waste to be treated can be adjusted. Thus, the alkali concentration and the amount of the alkali aqueous solution 28 can be changed.

The waste slurry into which the alkaline aqueous solution 28 has been injected into the waste slurry fed by the high-pressure pump 13 is heated to the reaction temperature before the supply to the reactor 14, and the temperature is raised from room temperature. Reaction temperature of 250 to
Heat to 350 ° C. Therefore, the first heat exchanger 1
6, the second heat exchanger 18 is disposed in front of the reactor 14,
The temperature of the first heat exchanger 16 and the second heat exchanger 18 is increased stepwise. First heat exchanger 16, second heat exchanger 18
Is preheated by the heat of the flash steam generated when the waste slurry is flashed from the reactor 14 to the flash evaporator 20, and then the waste slurry is passed between the heating medium heating furnace 34 and the second heat exchanger 18. The temperature is raised to a reaction temperature of 250 to 350 ° C., desirably about 325 ° C. by a circulating heat medium, and is introduced into the reactor 14.

The slurry is held for several tens of minutes in the reactor 14, and the liquid pressure is set to be higher than the saturated vapor pressure at that temperature to prevent boiling. The reaction slurry from the reactor 14 is flushed to the flash evaporator 20 and reduced in pressure to atmospheric pressure, at which time steam is generated. In the process of concentrating the reaction slurry stored in the flash evaporator 20 by a centrifugal filter or the like forming the separation means 24,
Fuel cake 27 and filtrate 2 washed with flash condensate
And 9 are separated.

Here, depending on the amount of vinyl chloride in the municipal solid waste and industrial waste, it is determined whether or not a part or all of the filtrate 29 separated by the separation means 24 is to be sent to the electrolytic device 50. It does. First, when the amount of vinyl chloride in the raw material waste such as municipal waste and industrial waste is large, as shown in FIG. 1, the entire filtrate 29 is fed to the electrolytic means 26 and subjected to the electrolytic reaction. In the electrolysis device 36 using the ion exchange membrane 38 as the electrolysis means 26, the filtrate 29 introduced into the anode chamber 46 constituting the electrolysis device 36 is used.
Generates chlorine gas by the anode 40 and moves an alkali metal such as Na ion through the ion exchange membrane 38 to the cathode chamber 48 having the cathode 42. Thus, the remaining filtrate 29 in the anode chamber 46 from which sodium chloride (NaCl) has been removed is introduced into the cathode chamber 48 having the cathode 42 through the return pipe 44.

At the cathode 42, hydrogen gas is generated from hydrogen ions, and hydroxyl ions remain in the anode chamber 46. As described above, alkali metal (Na) ions enter the cathode chamber 48 through the ion exchange membrane 38 from the anode chamber 46, so that a base (NaOH) is generated, and the alkaline aqueous solution 28 is discharged from the outlet of the cathode chamber 48. It is fed to the alkaline aqueous solution tank 30.

On the other hand, when the amount of vinyl chloride in the raw material waste such as municipal waste and industrial waste is small, a part (X) of the filtrate 29 is supplied to the electrolytic means 26 as shown in FIG. And the remaining filtrate 29 (Y) is supplied to the electrolytic means 2
The waste water is directly recycled as water for adjusting the waste slurry in the pretreatment step without passing through Step 6. The X of the filtrate 29
And the ratio of Y are determined so as to maintain the amount of sodium chloride in the system at a predetermined value.

On the other hand, an electrolyzer using a diaphragm method will be described with reference to FIG. In the electrolysis device 50 using the diaphragm method,
The filtrate 29 introduced into the anode chamber 58 constituting the electrolysis device 50 generates chlorine gas by the anode 54. The remaining filtrate 29 passes through the diaphragm 52 and moves to the cathode chamber 60,
At this time, the alkaline aqueous solution 28 after the hydrogen gas has been generated by the cathode 56 in the cathode chamber 60 is discharged from the outlet of the cathode chamber 60 and fed to the alkaline aqueous solution tank 30.

In the above example, the steam generated by flash evaporation of the reaction slurry from the reactor 14 by the flash evaporator 20 is supplied to the first heat exchanger 16 for preheating the slurry, and the second heat exchanger 18 And heating medium heating furnace 3
While the waste slurry is preheated by the heated heat medium while circulating between the four heat exchangers, the first heat exchanger 16 is divided into multiple stages, while the flash is performed in multiple stages to obtain steam having different pressures. And the first heat exchanger 1 having a multi-stage structure
It is also possible to increase the amount of heat recovery by supplying to each stage of No. 6. Further, by providing a vapor compressor and pressurizing the flash steam, it is possible to increase the condensation temperature and increase the heat recovery. Further, as shown in FIG. 5, it can be used as a system obtained by adding a self-heat exchange system to the system shown in FIG.

Further, as shown in FIG. 6, based on the system shown in FIG. 1, the reaction slurry is once passed through a cooler 31 in order to effectively use the sensible heat of the reaction product slurry at the outlet of the reactor 14. A system in which a cooler 31 is disposed downstream of the reactor 14 and the heat medium is circulated and heated by the heat medium circulation pump 25 between the third heat exchangers 19 in order to utilize the heat medium for heating and energizing. Good.

[0041]

As apparent from the above description, the present invention has the following advantages. That is, since an aqueous alkaline solution for making the pH of the slurry discharged from the reactor weakly acidic is generated in the system, N 2 is newly added from the outside.
There is no need to supply a base such as aOH, and the cost of waste disposal is reduced. In contrast, a commercially available caustic soda solution requires transporting an alkaline aqueous solution generated by electrolysis to a user after evaporating and condensing, but the method does not require these operations and uses less energy. Since the decomposition reaction is remarkably accelerated, the solid waste is carbonized, the calorific value during combustion increases, and the fuel can be effectively used as an alternative fuel or a gasification source. In addition, by using part of the system as a heating source, the amount of heat supplied from the outside can be reduced. Chlorine gas as a useful substance can be collected and recycled as a chemical raw material or hydrochloric acid, and hydrogen gas can be obtained as a by-product, thereby expanding the range of applications to other uses. The amount of wastewater becomes zero or small, and the cost of wastewater treatment can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a system configuration block diagram of an embodiment according to the present invention.

FIG. 2 is a system block diagram in which a filtrate is subjected to electrolytic treatment using an electrolytic device using an ion exchange membrane.

FIG. 3 is a system block diagram in which a filtrate is subjected to electrolytic treatment using an electrolytic device using a diaphragm.

FIG. 4 is a system mechanism block diagram of an embodiment in a case where a small amount of vinyl chloride is contained in solid waste.

FIG. 5 is a system block diagram of a second case.

FIG. 6 is a system block diagram of a third case.

DESCRIPTION OF SYMBOLS 10 Pretreatment means 12 Storage tank 13 High pressure pump 14 Reactor 16 First heat exchanger 18 Second heat exchanger 19 Third heat exchanger 20 Flash evaporator 24 Separation means 25 Heat medium circulation pump 26 Electrolysis Means 27 Cake 28 Alkaline aqueous solution 29 Filtrate 30 Alkaline aqueous solution tank 31 Cooler 32 Alkaline aqueous solution supply pump 34 Heat medium heating furnace 36 Electrolyzer 38 Ion exchange membrane 40 Anode 42 Cathode 44 Return pipe 46 Anode chamber 48 Cathode chamber 50 Electrolyzer 52 Diaphragm 54 Anode 56 Cathode 58 Anode compartment 60 Cathode compartment

Claims (9)

[Claims] 1. A solid waste containing a large amount of vinyl chloride or other chlorine-containing resin is converted into a waste slurry by a pretreatment means, and the slurry is hydrothermally reacted in a reactor to obtain a reaction slurry. A method for treating waste which is obtained by obtaining a cake-like dechlorinated raw fuel and a filtrate by dehydration subsequent to flashing, wherein said filtrate is subjected to electrolytic treatment to recover and circulate as an aqueous alkaline solution. Characteristic waste treatment method. 2. The method according to claim 1, wherein chlorine gas and hydrogen gas generated when the filtrate is subjected to electrolytic treatment are taken out of the system, and the remaining alkaline aqueous solution is circulated and used as a neutralizing agent for the waste slurry. The method for treating waste according to claim 1. 3. The cake-like fuel after the dechlorination is burned in a combustion furnace, a heat medium is heated by combustion heat at the time of the combustion, and the heat medium is provided in a path leading to a reactor. The method for treating waste according to claim 1, wherein the waste slurry is heated through an exchanger. 4. The steam generated at the time of said flashing is passed through a heat exchanger provided in a path leading to a reactor to be used for heating waste slurry, and a condensate discharged from the heat exchanger after heat exchange is used. 2. The method for treating waste according to claim 1, wherein the slurry is circulated and used as washing water in a dehydrating means of the reaction slurry. 5. The method according to claim 1, wherein the condensed liquid is circulated in the system as washing water for the dehydrating means of the reaction slurry, and replenishing water is supplied from outside when the condensed liquid is insufficient. Item 6. The waste disposal method according to Item 4. 6. The waste treatment according to claim 1, wherein the filtrate is subjected to electrolytic treatment by an ion exchange membrane method or a diaphragm method, and an alkaline aqueous solution obtained by the electrolytic treatment is recycled. Method. 7. The filtrate is subjected to electrolytic treatment by an ion exchange membrane method or a diaphragm method having an anode and a cathode to generate chlorine gas from the anode and hydrogen gas from the cathode. 2. The method for treating waste according to claim 1, wherein the waste is circulated and used as an aqueous solution. 8. A solid waste containing a large amount of vinyl chloride or other chlorine-containing resin is converted into a waste slurry by a pretreatment means, and the slurry is hydrothermally reacted in a reactor to obtain a reaction slurry. What is claimed is: 1. A waste treatment apparatus for obtaining a cake-like dechlorinated raw fuel and a filtrate by dehydration following a flash, wherein electrolytic means capable of electrolytically treating the filtrate is provided. Equipment for processing objects. 9. The apparatus for treating waste according to claim 8, wherein said electrolysis means is an electrolysis means using an ion exchange membrane method or a membrane method having an anode and a cathode, respectively.