JPH11267698A - Treatment of waste and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce running cost without needing a large quantity of heat energy for the evaporation of water by dewatering a mixed waste slurry after hydrothermal reaction to obtain a cake-like dechlorinated fuel and raw material and a filtrate and electrolyzing the filtrate to recover and circulate as an aq. alkali solution. SOLUTION: A raw material waste such as municipal refuse contains a large quantity of vinyl chloride and other chlorine-containing resins, which forms hydrogen chloride with the pyrolysis. Then, a base is added to make a waste slurry, the slurg is allowed to hydrothermally react in a reactor 14 and the resultant reacting slurry is separated into a cake 27 and a filtrate 29 by a filtrating means. The filtrate 29 therein is fed to a electrolytic means to be electrolyzed. The aq. alkali solution 28 is once stored in an aq. alkali solution tank 30 and hydrogen chloride generated in the hydrothermal reaction is neutralized by adding the aq. alkali solution 28 in the waste slurry to cyclically use.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a waste slurry containing a large amount of organic solids such as municipal solid waste and industrial waste, especially vinyl chloride and other chlorine-containing resins, and a waste slurry such as industrial wastewater or municipal wastewater. The waste slurry mixed with the organic sludge obtained by the treatment of the wastewater that dissolves the organic matter is converted into a cake that has been converted into a fuel by dehydration after the hydrothermal decomposition reaction, and the filtrate is electrolytically treated to dissolve the alkaline aqueous solution. The present invention relates to a method and an apparatus for treating waste, which are to be recycled and used.

[0002]

2. Description of the Related Art As organic sludge, sewage sludge discharged in large quantities from domestic wastewater treatment is representative in addition to sludge discharged from industrial wastewater treatment of pulp, fiber, chemical, food and the like. . The sewage sludge discharged from the sewage treatment plant has a high water content of 98%, is enormous, and is increasing year by year. Conventionally, about 80% of such sewage sludge treatment is dewatered and landfilled.
However, in this case, there is a problem of securing a landfill, and the development of urbanization has made it difficult to secure the landfill year by year. Sewage sludge can also be incinerated, but this method is incinerated ash whose treatment product is significantly reduced in volume compared to the amount of sewage sludge that is the raw material to be treated.
This is a very effective method from the viewpoint of reducing the volume of the raw material to be processed.

On the other hand, so-called 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, and conventional disposal methods such as landfills cannot be used. I have. From this perspective,
After crushing solid waste in water and collecting useful materials such as iron, aluminum, glass, etc. that can be recycled in the form of a water slurry, dehydrate it to a state with an appropriate moisture value, and then under high temperature and high pressure conditions A high-temperature and high-pressure reaction product slurry obtained by a hydrothermal reaction at a predetermined residence time is finally reduced to atmospheric pressure to obtain a product slurry.

[0004]

However, in the case of the former sewage treatment method, since a large amount of water is contained in the cell membrane of the sludge, even a cake having a high dehydration degree has a high water content of 80% and has a high self-combustibility. In addition, incineration requires not only a combustion aid but also a large amount of heat energy for evaporating water, which results in high running costs and is not economical.

Further, the latter has the following problems when treating municipal waste or industrial waste containing a large amount of vinyl chloride or other chlorine-containing resin. When municipal waste and industrial waste containing a large amount of vinyl chloride and other chlorine-containing plastics are incinerated, there is a possibility that dioxin, a highly toxic substance, is generated, and there is 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 alkali salt with hydrochloric acid (sodium chloride) is highly corrosive and has limited solubility. It must be discharged outside the system so that it does not accumulate inside. 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.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic expanded sludge slurry obtained by pressurizing and heating an organic sludge, a vinyl-slurried slurry containing vinyl chloride or another chlorine-containing system. A solid waste slurry containing a large amount of resin is mixed to form a mixed waste slurry, and the slurry is converted into a cake made into a fuel by dehydration after the hydrothermal decomposition reaction, and the filtrate is subjected to electrolytic treatment to form an aqueous alkaline solution. It is an object of the present invention to provide a method and an apparatus for treating waste which are used in a reaction system in a circulating manner.

[0007]

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 supplied to the mixing tank, and the organic sludge is pressurized and heated, and then instantaneously depressurized to expand the sludge, thereby producing an expanded sludge slurry. The slurry is subjected to a hydrothermal reaction in a reactor to obtain a reaction slurry, and then dewatered after flashing to obtain a cake-like dechlorinated raw fuel and a filtrate. So,
The filtrate was electrolytically treated to recover and circulate as an aqueous alkaline solution.

In the second invention, which is 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 contained in the waste slurry. In the third aspect of the invention, which is mainly based on the first aspect, the cake-like fuel after the dechlorination is burned in a combustion furnace. The medium was heated and the mixed medium slurry was heated by passing the heat medium through a heat exchanger provided in a path leading to the reactor.

[0009] 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 provided in a path leading to the reactor to heat the mixed waste slurry, and the condensate discharged from the heat exchanger after the heat exchange is dehydrated by the reaction slurry dehydrating means. In the fifth invention, which is mainly based on the fourth invention, the condensed liquid is circulated in the system as the washing water for the dehydrating means of the reaction slurry, and the condensate is used as the washing water. When the liquid is insufficient, make-up water is supplied from outside.

[0010] In a sixth invention mainly based on the first invention,
The filtrate is electrolytically treated 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. I made it. In the seventh invention mainly based on the first invention, when solid waste contains a large amount of vinyl chloride or other chlorine-containing resin,
The entire amount of the filtrate is subjected to electrolytic treatment by electrolytic means, and when the solid waste contains a medium amount of vinyl chloride or other chlorine-containing resin, a part of the filtrate is subjected to electrolytic treatment to obtain an alkaline aqueous solution. , The remaining filtrate is fed to the pretreatment means by bypassing the electrolysis means at the same time as being fed to the pretreatment means or the downstream side of the mixing tank, and furthermore, vinyl chloride and other chlorine-containing resins are contained in the solid waste. Is contained in a small amount, the amount required for neutralization is supplied to the downstream side of the mixing tank from the alkaline aqueous solution tank storing the alkaline aqueous solution.

In the eighth invention, solid waste containing a large amount of vinyl chloride or other chlorine-containing resin is converted into waste slurry by a pretreatment means and supplied to the mixing tank, and the organic sludge is pressurized. After heating, the pressure is released and the sludge is expanded to generate an expanded sludge slurry, which is supplied to the mixing tank to obtain a mixed waste slurry, and the slurry is hydrothermally reacted in a reactor to obtain a reaction slurry. After the flushing, the wastewater was dewatered after dehydration to obtain a cake-like dechlorinated raw fuel and a filtrate, and an electrolytic means capable of electrolytically treating the filtrate was provided.

[0012] In a ninth invention mainly based on the eighth invention,
The electrolysis means was an electrolysis means using an ion exchange membrane method or a membrane method having an anode and a cathode, respectively.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of the method and apparatus for treating waste according to the present invention will be described below with reference to FIGS.
This will be described in detail with reference to FIG.

FIG. 1 is a block diagram of a system configuration of an embodiment in which a large amount of vinyl chloride is contained in solid waste according to the present invention. FIG. 2 shows an example in which a filtrate is subjected to electrolytic treatment using an electrolytic apparatus by an ion exchange membrane method. System block diagram, Figure 3
Is a system block diagram in which a filtrate is subjected to electrolytic treatment using an electrolysis device by a diaphragm method, FIG. 4 is a system configuration block diagram of an embodiment in a case where a small amount of vinyl chloride is contained in solid waste according to the present invention, and FIG. FIG. 6 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 or other chlorine-containing resin is pretreated in a pretreatment step.

In the pretreatment step, when treating wastes containing a large amount of unseparated vinyl chloride and other chlorine-containing resins, useful materials such as iron, aluminum and glass which can be recycled are included. Therefore, it is necessary to collect the waste first and to make the solid waste into a slurry that can be transported for the continuous operation of the solid waste treatment system. A pretreatment means 10 for this purpose is provided, and this pretreatment means 10 is composed of a crushing device, a separation device for useful materials, a dewatering device, and the like.

Therefore, in the pretreatment means 10, the solid waste containing the organic solid matter in an unsorted state is made into a water slurry by crushing in water, and in this slurrying step, the non-combustible material contained in the crushed material is 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 solid waste slurry treated by the pretreatment means 10 is a room temperature slurry, and is once mixed in the mixing tank 6.
8 is stored. Here, a buffer between the processing of the pre-processing means 10 and the subsequent processing is formed. To the mixed waste slurry discharged from the mixing tank 68, an alkaline aqueous solution 28 to be circulated is added. The mixed waste slurry in the mixing tank 68 is supplied to the subsequent reactor 14 as a mixed waste slurry in which a base is mixed by a pumping means such as a high-pressure pump 13, and water is supplied while flowing through the reactor 14. A thermal reaction is caused.

Next, expansion treatment of the other organic sludge will be described. In FIG. 1, organic sludge generated as a residue of the treatment of industrial wastewater or domestic wastewater is dehydrated for transport handling in a wastewater treatment facility, and is usually in the form of a cake having a water content of 78 to 83% by weight. It has become. This dehydrated sludge is mostly composed of microbial cells, and the sludge is covered with a cell membrane containing water. This cell membrane is not destroyed by a simple dehydration treatment, so that it is difficult to dehydrate sludge below the above-mentioned water content.

The organic sludge showing such a cake form is temporarily stored in a bunker (not shown), and is supplied by pressure to a downstream processing system by a screw pump 70 attached to the bunker. A preheater 74 is interposed in the sludge feed line 72 from the screw pump 70 to raise the temperature in advance before introducing the conveyed sludge into the sludge expansion reactor 76 to reduce the heat load in the sludge expansion reactor 76. I'm making it smaller.

The sludge expansion reactor 76 pressurizes and heats the introduced preheated sludge, and is configured as a closed vessel. A pressure regulating valve (about 7 kg / cm 2) is used to maintain the pressure at about 7 kg / cm 2. (Not shown). In the sludge expansion reactor 76, the sludge is uniformly heated to 160 to 170 ° C., and the sludge cell membrane is destroyed by thermal alteration, and at the same time, a part of the water in the sludge evaporates to obtain a pressure in a gas-liquid equilibrium state. I can do it. Here, a flash valve (not shown) is provided between the sludge expansion reactor 76 and the flash evaporator 78 for instantaneously flashing the pressurized heated sludge into the flash evaporator 78 and opening it to atmospheric pressure. It is provided on the provided pipe 80.

Therefore, the heated sludge in the pressurized state is instantaneously released to the atmospheric pressure by passing through the flash valve, and a part of the water present in the sludge cell membrane is rapidly vaporized and expanded by the depressurization. Then steam is generated. This action promotes the destruction of the cell membrane of the sludge particles, and elutes water and makes the sludge cell membrane finer, thereby producing an expanded sludge slurry having an extremely high fluidity, and the piping 8
2 and stored in the mixing tank 68. The mixed waste slurry stored in the mixing tank 68 is fed 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 in the reactor 14. It is trying to happen.

The operating temperature in the reactor 14 is from 250 to 350
The temperature is raised to an appropriate temperature of about
The mixed waste slurry obtained by mixing the base while being pressurized to about 170 atm by step 3 is fed, and the temperature is raised in advance to the reaction temperature in the preceding stage of the reactor 14. In the embodiment, the first heat exchanger is used. 16 and the second heat exchanger 18
Then, the temperature is raised stepwise to the reaction temperature and then fed to the reactor 14. As a result, the mixed 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 several minutes to tens of minutes. In time, it is pyrolyzed by a hydrothermal reaction.

In the present embodiment, the reaction slurry after the hydrothermal reaction in the reactor 14 uses the flash evaporator 20 as a cooling device, and the steam generated by the flash evaporation is converted into the first heat exchanger 16 and the sludge expansion reactor 56. Supply system. That is, the temperature is raised stepwise to the reaction temperature and then sent to the reactor 14 to cause a hydrothermal reaction under predetermined operating conditions, and the steam flashed by isenthalpy expansion using the flash evaporator 20 is used as the first steam. 1 The heat exchanger 16 and the sludge expansion reactor 56 are used for heating. 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.

The flash liquid which has been flashed from the reactor 14 to the flash evaporator 20 and stored therein is dechlorinated with the filtrate 29 containing dissolved gas, salt and the like by using a separation means 24 such as a centrifuge. Separated into the fuel cake 27. The fuel cake 27 is burned in the heating medium heating furnace 34, and the heat medium circulating between the second heat exchanger 18 and the heating medium heating furnace 34 is heated by the combustion heat. First heat exchanger 16
The flash steam after heating the mixed waste slurry mixed with the base and the flash steam after heating the organic sludge in the sludge expansion reactor 76 are condensed. It is used as a washing liquid for the fuel cake 27 obtained by the separation. When washed with the condensate, the mother liquor containing chlorine ions in the fuel cake 27 is replaced with the condensate, and the 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 mixed waste slurry 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. When the proportion of the chlorine-based resin contained in the industrial waste is large, the entire filtrate 29 is supplied to the electrolytic means 2.
6 (see FIG. 1). When the amount of chlorinated resin contained in municipal solid waste or industrial waste is medium, a part of the filtrate 29 (X in FIG. 4) is sent to the electrolytic means 26 and the remaining amount The filtrate 29 (Y in FIG. 4) is
6, the water is directly recycled as slurry adjusting water in the pretreatment step. A case where the entire filtrate 29 is fed to the electrolytic means 26 will be described with reference to FIG. The filtrate 26 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 device 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 into the chamber.
Is arranged.

An anode 40 is provided in the anode chamber 46 leading to 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 type is usually used. After generating chlorine gas 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.

The case where a cationic type is used as the ion exchange membrane 38 has been described above. 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 42 generates hydrogen gas by an electrode reaction and generates chlorine gas from the anode 40, and then alkali metal ions such as OH move to the anode chamber 46 through the ion exchange membrane 38. By doing so, sodium hydroxide (NaOH) will be generated,
Eventually, the filtrate 29 undergoes an electrode reaction to become an alkaline aqueous solution 28 which is a decomposition solution.

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.

Incidentally, the raw material waste such as municipal solid waste, which is the raw material of the present invention, contains a large amount of vinyl chloride and other chlorine-containing resins, and the chlorine compound generates hydrogen chloride upon thermal decomposition. I do. For this reason, as described later, a waste slurry in which a base is mixed is formed, and the slurry is hydrothermally reacted in the reactor 14 and the reaction slurry obtained is separated by the separation means 24 to obtain the cake 27 and the filtrate 29. However, when the filtrate 29 is fed to the electrolytic 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 supplied in a continuous injection system, and the injection amount is an amount necessary for neutralizing the generated chlorine compound. When the content is large, it is necessary to increase the alkali concentration or the addition amount of the alkaline aqueous solution 28.

The alkaline concentration of the alkaline aqueous solution 28, which is an alkaline substance, is controlled by the amount of electric current for electrolysis, and the injection position is such that it is injected immediately below the mixing tank 68. Mixing tank 68
It may be supplied directly to. 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.

Municipal waste and industrial waste containing a large amount of vinyl chloride and other chlorine-containing resins in the organic solid matter are introduced into the treatment system in a mixed unsorted state. The unsorted waste is mixed with the aqueous alkali solution 28 or the filtrate 29 in the first pretreatment means 10 and pulverized to form an aqueous slurry, from which useful inorganic substances such as iron and aluminum are separated to contain waste containing organic solids. Produce a slurry. The pulverization treatment may be performed so that the solid matter is reduced to about several mm by underwater crushing, thereby forming an aqueous slurry and separating and removing iron and the like during the underwater crushing. The aqueous slurry is then charged into a cyclone where useful materials such as aluminum and glass are separated, and the slurry containing organic solids is solidified to a solid concentration (approximately 1) within a range that can be pumped through a dehydrator.
(4% by weight) and put into the mixing tank 68.

On the other hand, in the treatment of organic sludge, the cake obtained by dehydrating the organic sludge generated by the treatment of industrial wastewater or domestic wastewater until it has a water content of 78 to 83% by weight is received. Then, after being preheated from the screw pump 70 by the preheater 74 on the way, it is fed to the sludge expansion reactor 76 and further pressurized and heated. The organic sludge pressurized and heated in the sludge expansion reactor 76 is introduced into a flash evaporator 78 and instantaneously released to the atmospheric pressure to become an expanded sludge slurry, which is sent to the mixing tank 68.

In the mixing tank 68, the solid waste slurry and the expanded sludge slurry are stirred by a stirrer (not shown) to obtain a uniform mixed waste slurry. The mixed waste slurry is fed to the reactor 14 by the high-pressure pump 13. At the outlet of the mixing tank 68, the alkaline aqueous solution 28 is continuously mixed from the alkaline aqueous solution tank 30 through the alkaline aqueous solution supply pump 32. A part of the alkaline aqueous solution 28 is injected into the waste slurry,
May be sent to

The alkaline aqueous solution 28 is supplied to the reactor 1
The pH of the reaction slurry at the outlet of No. 4 is a weakly acidic pH = 3 to
6, preferably 4 to 6, the amount of addition (alkaline concentration in alkaline water) may be adjusted. By controlling the electrolysis current so that the pH value of the reaction slurry at the outlet of the reactor 14 becomes weakly acidic, continuous operation of the treatment of the composite waste becomes possible. Further, by changing the alkali concentration and the addition amount of the alkali aqueous solution 28 according to the amount of vinyl chloride or other chlorine-containing resin in the solid waste to be treated, the outlet pH value of the reactor 14 is detected,
The pH value can be adjusted to a predetermined value.

The mixed waste slurry in which the alkaline aqueous solution 28 has been injected into the mixed waste slurry fed by the high-pressure pump 13 is heated to the reaction temperature before being supplied to the reactor 14, Is the reaction temperature 2
Heat to 50-350 ° C. For this reason, the first heat exchanger 16 and the second heat exchanger 18 are arranged in front of the reactor 14, and the first heat exchanger 16 and the second heat exchanger 18 gradually increase the temperature. I have. The mixed waste slurry sent through the first heat exchanger 16 and the second heat exchanger 18 is first preheated by the heat of the steam generated by the subsequent flash, and then the second heat exchange with the heat medium heating furnace 34. The reaction medium is heated to a reaction temperature of 250 to 350 ° C., desirably about 325 ° C. by a heat medium circulating between the vessels 18 and 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. The reaction slurry stored in the flash evaporator 20 is separated into a fuel cake 27 and a filtrate 29 which have been washed with a condensate of flash steam in a process of being concentrated through a centrifugal filter or the like constituting a separation means 24.

Here, when the filtrate 29 separated by the separation means 24 is fed to the electrolytic device 50 depending on the amount of vinyl chloride in the municipal solid waste or industrial waste as the raw material of the present invention, the filtrate 29 A decision is made whether to send some or all. First, if the amount of vinyl chloride in municipal solid waste and industrial waste is large,
As shown in (2), the whole of the 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 generates chlorine gas by the anode 40 and, for example, an alkali such as Na ion. The metal is passed through the ion exchange membrane 38 and the cathode 42
To the cathode chamber 48 having 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, since alkali metal (Na) ions enter the cathode chamber 48 through the ion exchange membrane 38 from the anode chamber 46, the base (N
aOH) is generated, the alkaline aqueous solution 28 is discharged from the outlet of the cathode chamber 48, and is supplied to the alkaline aqueous solution tank 30.

On the other hand, when the amount of vinyl chloride in the municipal solid waste or industrial waste is medium, a part (X) of the filtrate 29 is fed to the electrolytic means 26 as shown in FIG. The alkaline aqueous solution 28 that has been processed and generated by electrolysis is once supplied to an alkaline aqueous solution tank 30. Thereafter, the required amount is supplied from the alkaline aqueous solution tank 30 to the feed line of the mixed waste slurry via the alkaline aqueous solution supply pump 32, and the remaining filtrate 29 (Y) is passed through the electrolytic unit 26 without passing through the electrolytic unit 26. After forming the bypass line of 26, it is directly recycled as water for adjusting waste slurry in the pretreatment step. The ratio of X and Y in the filtrate 29 is determined so that the amount of sodium chloride in the system is maintained at a predetermined value. Further, when the amount of vinyl chloride in the municipal solid waste or industrial waste is small, the required amount of the alkaline aqueous solution 28 is supplied from the alkaline aqueous solution tank 30 through the alkaline aqueous solution supply pump 32 without supplying the same to the pretreatment means 10. The mixed waste slurry is supplied to the feed line.

On the other hand, an electrolyzer according to the 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 centrifuged by the separation means 24. The fuel cake 27 obtained as described above was circulated between the second heat exchanger 18 and the heating medium heating furnace 34 to preheat the mixed waste slurry with the heated heating medium. While the heat exchanger 16 is divided into multiple stages, flash is performed in multiple stages to obtain steam with different pressures, and the steam is supplied to each stage of the first heat exchanger 16 configured in multiple stages to increase the amount of heat recovery. Is also possible. 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 utilize the sensible heat of the reaction slurry at the outlet of the reactor 14. In order to use the medium for heating and energizing, a system may be provided in which a cooler 31 is disposed downstream of the reactor 14 and the heat medium is circulated and heated between the third heat exchangers 19 by the heat medium circulation pump 64. .

[0047]

As apparent from the above description, the present invention has the following advantages. That is, since an alkaline aqueous solution for making the pH of the slurry discharged from the reactor weakly acidic is generated in the system, it is not necessary to newly supply NaOH for neutralization from the outside, and the waste disposal cost is reduced. . Since the decomposition reaction is remarkably accelerated, the solid waste is converted to solid carbon, and the effective use as an alternative fuel or a gasification source becomes possible due to an increase in heat generation due to dechlorination and a decrease in the water content. 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 recovered and used as a chemical raw material such as hydrochloric acid, and hydrogen gas can be obtained as a by-product, thereby expanding the range of use for other uses. The amount of wastewater becomes zero or small, and the cost of wastewater treatment can be greatly reduced. Sludge can be converted to a self-burning combustion cake.

[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 configuration block diagram of an embodiment when a small amount of vinyl chloride is contained in solid waste according to the present invention.

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 13 High-pressure pump 14 Reactor 16 First heat exchanger 18 Second heat exchanger 19 Third heat exchanger 20 Flash evaporator 24 Separation means 26 Electrolysis means 27 Fuel cake 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 Separator 54 Anode 56 Cathode 58 Anode chamber 60 Cathode chamber 64 Heat medium circulation pump 68 Mixing tank 70 Screw pump 72 Sludge feed line 74 Preheater 76 Sludge expansion reactor 78 Flash evaporator 80, 82 Piping

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 supplied to a mixing tank, and the organic sludge is pressurized and heated. The slurry is depressurized and the sludge is expanded to generate an expanded sludge slurry, which is supplied to the mixing tank to form a mixed waste slurry, and the slurry is hydrothermally reacted in a reactor to obtain a reaction slurry. A waste disposal method for obtaining a cake-like dechlorinated raw fuel and a filtrate by subsequently dehydrating the filtrate, wherein the filtrate is electrolytically treated to recover and circulate as an aqueous alkaline solution. 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 waste treatment method according to claim 1, wherein the mixed waste slurry is heated through an exchanger. 4. The mixed waste slurry is heated by passing the steam generated at the time of the flash through a heat exchanger disposed in a path leading to a reactor, and reacting a condensate discharged from the heat exchanger after the heat exchange. 2. The method according to claim 1, wherein the slurry is circulated and used in the system as washing water for the dehydrating means.
Waste treatment method as described. 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 electrolytic treatment of the filtrate 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. The waste disposal method according to claim 1, wherein the waste is recycled. 7. When the solid waste contains a large amount of vinyl chloride or another chlorine-containing resin, the entire amount of the filtrate is subjected to electrolytic treatment by electrolytic means, and the solid waste contains vinyl chloride or another chlorine-containing resin. When the system resin is contained in an intermediate amount, a part of the filtrate is subjected to electrolytic treatment to obtain an alkaline aqueous solution, and then the remaining filtrate is supplied to the downstream side of the pretreatment means or the mixing tank and the remaining filtrate is bypassed through the electrolytic means. When the solid waste contains a small amount of vinyl chloride or other chlorinated resin, the amount necessary for neutralization is mixed from the alkaline aqueous solution tank storing the alkaline aqueous solution. 2. The method for treating waste according to claim 1, wherein the waste is supplied to a downstream side of the tank. 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 supplied to a mixing tank. The expanded sludge slurry is generated by pressurizing and expanding the sludge, supplied to the mixing tank to form a mixed waste slurry, and the slurry is hydrothermally reacted in a reactor to obtain a reaction slurry. What is claimed is: 1. A waste treatment apparatus comprising a dewatered cake-like dechlorinated raw fuel and a filtrate, wherein an electrolytic means capable of electrolytically treating the filtrate is provided. apparatus. 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.