JP2001335660A - Recycling method of organic waste materials including vinyl chloride resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recycling method of waste materials including much vinyl chloride resin (chloride compound) as the resource without separation by gasification via partial oxidation, where the washing water containing a large quantity of sodium chloride is converted into fresh water by a reverse osmosis membrane. SOLUTION: This recycling process comprises the steps of feeding organic waste materials without separation directly to a gasification device, gasifying by partial oxidation to obtain a synthetic gas containing hydrogen chloride, sending the gas to a scrubber to contact the gas with washing water containing NaOH to neutralize and remove the hydrogen chloride in the gas, adding NaOH to the water discharged from the scrubber to recycle as the circulating water, blowing down a part of washing water to keep the concentration of sodium chloride at the level of 0.1 to 1% while most part of washing water is recycled after adding a base such as NaOH, sending the blown down water to a reverse osmosis membrane device to separate into fresh water containing little NaCl and concentrated salt water, recycling the obtained fresh water to the scrubber as the circulating water, and electrolyzing the concentrated salt water by the diaphragm process electrolysis device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recycling technology for treating and recycling waste containing an organic chlorine compound such as vinyl chloride, and more particularly, to recycling organic waste such as vinyl chloride containing hydrogen chloride by partial oxidation. The present invention relates to a method for recycling organic waste containing vinyl chloride resin for producing synthesis gas and efficiently treating hydrogen chloride as a by-product.

[0002]

2. Description of the Related Art When organic chlorine compounds such as vinyl chloride are contained in waste, the recycling technology that treats the waste and turns it into resources generates hydrogen chloride in the process of processing, which causes problems such as corrosion of equipment and dioxin. There are various countermeasures. For example, in the technology of oiling waste plastic, vinyl chloride is separated by pretreatment or dehydrochlorination by thermal decomposition, and then oiling is performed without chlorine. In addition, in the technology of using waste plastics in steelmaking blast furnaces, the same plastics are introduced into steelmaking blast furnaces after dehydrochlorination.

[0003]

As described above, in the oiling technology and the technology of using vinyl chloride-containing waste plastic in the steelmaking blast furnace, the vinyl chloride is separated as a pretreatment,
Alternatively, after the dehydrochlorination treatment by thermal decomposition, the treatment is recycled. The cost required for such preprocessing accounts for a considerable portion of the cost of recycling, and a technique for recycling resources in an unsorted state is desired. The present invention is to recycle in an unsorted state by gasification. In this case, hydrogen chloride is generated when waste containing organic chlorine compounds such as vinyl chloride is partially oxidized and gasified in an unsorted state, but hydrogen chloride in the gas is highly corrosive and is generated with water containing alkali. The gas is neutralized and removed, but the alkali salt of hydrochloric acid (sodium chloride) generated by the neutralization is highly corrosive, has a limited solubility, and is discharged out of the system to minimize accumulation in cleaning water. There is a need to.

[0004] Therefore, in the case where waste containing a large amount of vinyl chloride resin (chlorine compound) is gasified by a partial oxidation method and recycled as resources, it is necessary to treat washing water containing a large amount of sodium chloride. At this time, it is not a preferable method to flow the water as wastewater into the public water area because wastewater treatment centering on COD removal is required and a large amount of make-up water corresponding to the wastewater treatment is required. On the other hand, salt (N
A method of crystallizing and separating aCl) and recycling water requires a large amount of heat energy to evaporate most of the water.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to convert a waste containing a large amount of vinyl chloride resin (chlorine compound) into a gas by a partial oxidation method in an unfractionated state to recycle resources. In the method, the washing water containing a large amount of sodium chloride is desalinated by a reverse osmosis membrane, and the resulting concentrated salt water is subjected to electrolytic treatment of a glass fiber membrane in a diaphragm type electrolysis tank, and chlorine ions in the concentrated salt water are treated. The present invention aims to provide a method for recycling organic waste containing vinyl chloride resin, in which chlorine is discharged out of the system as chlorine gas, and an electrolytic solution is recycled as alkaline aqueous solution into washing water.

[0006]

In order to achieve the above object, according to a first aspect of the present invention, an organic waste containing a large amount of vinyl chloride or other chlorine-containing resin is directly separated in an unsorted state. The gas is supplied to a gasifier and gasified by the partial oxidation method to obtain a synthesis gas containing hydrogen chloride generated by the decomposition of an organic chlorine compound into a synthesis gas mainly composed of hydrogen, carbon monoxide, carbon dioxide, and water. Sending the gas out of the gasifier to a scrubber and bringing it into gas-liquid contact with washing water containing a base such as NaOH to neutralize and remove hydrogen chloride in the gas;
Simultaneously with obtaining a synthesis gas containing no hydrogen chloride gas, a base was added to the water leaving the scrubber and used as circulating water for gas-liquid contact. Blowdown is performed to maintain the water content from 1% to 1%, and the blown-down circulating water is sent to the reverse osmosis membrane equipment to separate the NaCl-reduced fresh water and the concentrated salt water. The concentrated brine was subjected to electrolytic treatment in a diaphragm electrolysis apparatus.

[0007] In the second invention according to the first invention,
The concentrated brine was electrolytically treated by a diaphragm method using a borosilicate glass fiber diaphragm, and the alkaline aqueous solution obtained by the electrolytic treatment was mixed with circulating water for circulating use.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The recycling method of organic waste containing vinyl chloride resin 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 method for recycling an organic waste containing a vinyl chloride resin according to the present invention, and FIG. 2 is a system block diagram in which a filtrate is treated using an electrolytic device using a diaphragm.

Hereinafter, FIG. 1 will be described in detail. First, the raw material to be treated is organic chlorine compound 1 such as vinyl chloride.
Organic waste containing a large amount of 0 and having a calorific value of 3000
It is about Kcal / Kg or more. When the calorific value is low, it can be used as a raw material by using it together with coal or the like. After pretreatment of the waste 10 containing organic solids in an unsorted state collected from various places, the waste 10 is supplied to a gasification step. In particular, in the present invention, the waste 10 containing a large amount of vinyl chloride or other chlorine-containing resin is supplied to the pretreatment step.

In the pretreatment step, when treating waste 10 containing a large amount of unpurified vinyl chloride or other chlorine-containing resin, useful materials such as recyclable iron, aluminum, and glass can be used. If so, it must be recovered first and crushed to an extent that solid waste can be transported for continuous operation of the gasification facility.
Pretreatment means for this purpose is provided, and this pretreatment means comprises a separation device and a crushing device for useful substances.

Therefore, in this pretreatment means, the solid waste 10 containing the organic solids in an unsorted state is separated into incombustibles and combustibles by the principle of a wind sieve, or crushed materials are produced by using a liquid cyclone. Utilizing the difference in specific gravity of incombustible substances contained therein, useful materials such as iron, aluminum and glass which can be recycled are collected. In the case of a separation device using a hydrocyclone, since the organic waste 10 is in a wet state with water, a scrubber 30 described later is used.
A part of the gas discharged from the organic waste 10 may be returned for drying, and the wet organic waste 10 may be dried using the sensible heat of the gas.

The organic waste 10 pulverized by the pretreatment means is supplied to a gasification facility 20 through a lock hopper (not shown) in an unsorted state. The organic waste 10 can be gasified by using any one of a fixed bed, a fluidized bed, a spouted bed, and a molten bed gasification facility as the gasification facility 20 here. Waste 10 containing chlorine compounds,
0.5 to 8 MPa (for example, 4 MPa) pressure and 120
Under a high temperature condition of 0 to 1500 ° C. (for example, 1400 ° C.), a synthesis gas composed of H 2, CO, CO 2, H 2 O, or the like can be obtained by a partial oxidation reaction. At this time, hydrogen chloride gas is generated from an organic chlorine compound such as a vinyl chloride resin.

The calorific value of the generated gas is obtained by heating the organic waste 10 to, for example, 1400 ° C. and subtracting the calorific value required for gasification. In this case, in order for the cold gas efficiency (the cold gas efficiency means the calorific value of the generated gas / the calorific value of the raw material waste) to be high and meaningful of recycling, at least the organic waste is required. The calorific value of 10 is preferably about three times or more the calorific value required for gasification. The combustion products of the organic waste 10 are roughly water, CO2
And soil and the like. The amount of heat required to heat the combustion products of these organic wastes 10 from 0 ° C. to 1400 ° C. is as follows. Water (liquid → gas) 1294 Kcal / Kg CO2 (gas → gas) 396 Kcal / Kg Soil (solid → liquid) 350 Kcal / Kg

In the case of the organic waste 10, since the amount of water contained is large, the amount of generated heat is small as a whole, and the amount of heat required for heating this to 1400 ° C. is often 1000 Kcal / Kg. Since it is assumed to be a degree, the above-mentioned 3000 Kcal / Kg is a standard.
When gasifying the water-containing organic waste 10, the water content of the organic waste 10 is reduced in advance, so that it is also effective to dry and increase the calorific value.

The synthesis gas generated in the gasification facility 20 contains carbon and hydrogen chloride gas generated from organic compounds such as vinyl chloride. For this reason, the synthesis gas introduced from the bottom of the scrubber and the water introduced from the top of the scrubber are brought into countercurrent contact to remove carbon and hydrogen chloride contained in the gas. In this case, caustic soda is added to the water side to neutralize hydrogen chloride in the gas and fix it as sodium chloride.

The water containing sodium chloride that has exited the scrubber 30 is sent to the washing water treatment step through the washing water line 60. In this case, the water that has exited the scrubber 30 is depressurized to atmospheric pressure in multiple stages, After the steam is collected, it enters the thickener 40, in which slag, carbon, etc. entrained at this time are settled and separated. Thereafter, the supernatant obtained by adding NaOH for neutralization to the supernatant of the thickener 40 was used as circulating water,
The water is circulated to the scrubber 30 through the circulating water line 70. An aqueous solution of sodium chloride obtained by neutralizing hydrogen chloride gas with caustic soda has the property of being highly corrosive under conditions of high concentration and high temperature.

For this reason, a part of the circulating water is extracted in order to keep the concentration of sodium chloride in the washing water sent from the thickener 40 to the scrubber 30 at, for example, 0.5%. However, a large amount of vinyl chloride resin is contained in the organic waste. , The amount of water to be extracted becomes very large. For example, when treating vinyl chloride resin (purity 100%) at 10 tons / day, the amount of generated sodium chloride is 9.36 tons / day, and to make the concentration of sodium chloride in the washing water 0.5%, 18
It is necessary to drain 72 tons / day of water.

The blow-down circulating water 85 is supplied to a reverse osmosis membrane facility 50 using a reverse osmosis membrane method to reduce the amount of wastewater.
Then, most of the wastewater is recycled so that it can be recycled. Reverse osmosis membrane equipment 50 is divided into a pretreatment step and a desalination step. In the pretreatment step, since the heat resistance of the reverse osmosis membrane is usually about 45 ° C., the circulating water blown down in advance is cooled to 35 to 40 ° C. by the cooling tower. Since small amounts of fine particles such as slag and carbon are contained in the washing water, they are removed by microfiltration.

Pretreated water (salt 0.5%, 5000 m
g / lit) to about 4 MPa to permeate the reverse osmosis membrane. As the reverse osmosis membrane, a commercially available one for desalination of saline water is used. By this treatment, fresh water having a salt content (NaCl) of about 300 mg / lit is obtained, and this fresh water is returned to the circulation line 70. The concentrated brine obtained when the circulating water is treated by the reverse osmosis membrane equipment 50 is supplied to the electrolysis device 90 in the next step at a concentration of about 5% (50,000 mg / lit) (10-fold concentration).

As shown in FIG. 1, the whole of the concentrated salt water 100 is fed to the electrolyzer 90 to be subjected to an electrolysis reaction. Here, the concentrated salt water 100 separates chlorine gas from the anode in the electrolysis device 90, electrolyzes into an aqueous solution containing caustic soda, and is recycled into the washing water 55 as alkaline water 110 for neutralization.

Next, the electrolytic apparatus 90 using the diaphragm method will be described with reference to FIG. The concentrated brine 100 generated by performing the pretreatment by the reverse osmosis membrane device 50 is separated into chlorine gas by the anode 92 in the electrolysis device 90 in the next step, and is electrolyzed into the alkaline aqueous solution 110 containing caustic soda (NaOH) to be neutralized. And mixed with circulating water 85 circulating from the thickener 40 to the scrubber 30 as an alkaline solution for use.

A filter cloth or filter paper made of borosilicate glass fiber is used for the diaphragm. In the electrolytic device 90 using the diaphragm method,
The diaphragm 93 divides the electrolytic cell into an anode chamber 91 and a cathode chamber 94. The concentrated brine 100 introduced into the anode chamber 91 constituting the electrolysis device 90 generates chlorine gas by the anode 92. The remaining liquid (a liquid from which most of the chloride ions have been removed from the concentrated brine 100) passes through the diaphragm 93 and moves to the cathode chamber 94. At this time, the hydrogen gas is generated by the cathode 95 in the cathode chamber 94 by the cathode 95. The alkaline aqueous solution 110 is discharged from the outlet of the cathode chamber 94, and is supplied from the alkaline line 105 to the scrubber 30 through the circulating water line 70.

Although electrolysis by the ion exchange membrane method is technically possible, divalent metal ions must be almost completely removed from the wastewater in order to prevent clogging of the ion (cation) exchange membrane. , Its operation is expensive and impractical. Further, asbestos has been conventionally used for the diaphragm, but asbestos is a substance causing environmental problems and is not preferred. Although a fluororesin diaphragm is also used as an electrolytic diaphragm, as shown in the examples, in the case of electrolysis of a saline solution having a high concentration such as concentrated saline solution 100, a diaphragm made of borosilicate glass fiber is used. However, both current efficiency and potential difference are excellent in performance.

[Embodiment] FIG. 3 shows a small electrolyzer 90 for electrolyzing concentrated brine 100. The electrolytic cell is made of vinyl chloride, and both the cathode chamber 94 and the anode chamber 91 have a capacity of four.
It is about 50 ml. A metal mesh iridium oxide-coated titanium electrode 0.3 dm 2 is used for the anode 92, and a metal mesh nickel electrode 0.3 dm 2 is used for the cathode 95. Here, the distance between the cathode 95 or the anode 92 and the diaphragm 93 is 3 mm.

In the electrolysis apparatus 90 shown in the embodiment, a test was conducted using two types of diaphragms 93 made of the following materials. That is, one of them is a glass fiber diaphragm, and the other is a fluororesin diaphragm. Table 1 shows a comparison of the performance of the two diaphragms 93. Table 1 Performance comparison of diaphragms

In this test, a sheet filter made of ultrafine borosilicate glass fiber was used as the glass fiber diaphragm. As the fluororesin diaphragm, a sheet-shaped filter made of tetrafluoroethylene resin (PTFE) as a raw material was used.

The following electrolysis test was performed using the electrolysis apparatus 90 described above. First, 200m 2% saline
It is supplied to the anode chamber 92 at 1 / hr, moved to the cathode chamber 94 through the diaphragm 93, and continuously extracted from the cathode chamber 94.
Next, a current of 3 A flows between the anode 92 and the cathode 95 to perform electrolysis. In this case, in the cathode chamber 94 and the anode chamber 92, stirring was performed with the stirrer placed in the electrolytic cell.

Electrolysis was carried out for about 7 hours using Teflon (registered trademark) and borosilicate glass fiber as the diaphragm 93. As a result, the results shown in Table 2 were obtained. Table 2 Comparison of electrolysis by difference of diaphragm That is, rather than using a fluororesin diaphragm from Table 2,
It can be seen that the use of a borosilicate glass fiber diaphragm can more efficiently electrolyze a high-concentration saline solution. As described above, the example using Na (sodium) as the alkali is shown, but the same effect can be obtained with K (potassium) and ammonia.

[0030]

As apparent from the above description, the present invention has the following advantages. That is, when incinerating waste containing an organic chlorine compound such as vinyl chloride, dioxin may be generated, but this treatment method does not cause dioxin. Waste containing organic chlorine compounds such as vinyl chloride can be gasified without separating and recycled into synthesis gas. Unlike the conventional case, a large amount of neutralized wastewater does not occur, the amount of wastewater can be reduced, and the cost of wastewater treatment is greatly reduced. There is no need to externally accept a base such as caustic soda as a raw material. Commercially available caustic soda concentrates about 30% of the electrolytic product to about 48% for transportation. However, in the present invention, since the alkaline aqueous solution produced by electrolysis is used as it is, the energy required for the concentrated transportation is unnecessary, resulting in a greenhouse effect. Gas emissions can also be reduced. Hydrogen gas is obtained as a by-product and chlorine gas can be recycled.

[Brief description of the drawings]

FIG. 1 is a block diagram of a method for recycling organic waste containing a vinyl chloride resin according to the present invention.

FIG. 2 is a system block diagram in which a filtrate treatment is performed using an electrolytic device using a diaphragm.

FIG. 3 is an electrolysis apparatus diagram for electrolyzing concentrated brine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Organic waste containing vinyl chloride 20 Gasification equipment 30 Scrubber 40 Thickener 50 Reverse osmosis membrane equipment 55 Washing water 60 Washing water line 70 Circulating water line 80 Fresh water 81 Electrolyzer 85 Circulating water 87 Blowdown water 90 Electrolyzer (Electrolysis) Apparatus) 91 Anode chamber 92 Anode 93 Separator 94 Cathode chamber 95 Cathode 100 Concentrated salt water 105 Alkaline line 110 Alkaline aqueous solution

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C02F 1/46 B01D 53/34 134B 1/469 C02F 1/46 103 // C08L 27:06 F term (reference ) 4D002 AA19 AC04 BA02 DA02 DA12 EA07 EA14 EA20 FA04 HA02 HA08 4D006 GA03 GA07 GA17 GA47 HA95 JA02Z KA01 KA12 KA72 KB01 KB14 KB19 MB02 MB07 MC04 MC04X PA01 PA02 PB07 PB08 PB27 PB28 PB70 EB80 EB13 EB35 FA01 FA09 FA11 FA13 FA20 GC05 4F301 AA17 CA25 CA26 CA41 CA52 CA72

Claims (2)

[Claims] 1. An organic waste containing a large amount of vinyl chloride or other chlorine-containing resin is directly supplied to a gasifier in an unsorted state and gasified by a partial oxidation method, and hydrogen, carbon monoxide, carbon dioxide gas is discharged. A synthesis gas containing hydrogen chloride generated by the decomposition of an organochlorine compound in a synthesis gas containing water as a main component, and a gas discharged from the gasifier being sent to a scrubber for washing water containing a base such as NaOH. And gas-liquid contact to neutralize and remove hydrogen chloride in the gas to obtain a synthesis gas containing no hydrogen chloride gas, and at the same time add a base to the water leaving the scrubber and use it as circulating water for gas-liquid contact At the same time, some of the circulating water is blown down in order to maintain the sodium chloride concentration at 0.1 to 1%, and the blown down circulating water is sent to a reverse osmosis membrane facility, and the NaCl-containing light water is reduced. After separating water and concentrated brine, the fresh water is recycled as a circulating water to a scrubber, and the concentrated brine is subjected to electrolytic treatment in a diaphragm electrolysis apparatus. 2. The concentrated brine is electrolytically treated by a diaphragm method using a borosilicate glass fiber diaphragm, and an alkaline aqueous solution obtained by the electrolytic treatment is mixed with circulating water for circulating use. The recycling method of organic waste containing vinyl chloride resin according to 1.