JPH10235309A - Dechlorination treatment of plastic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of more harmful chlorine gas at a time of heat treatment even if a plastic material is heat-treated by converting harmful chlorine gas to form harmless chloride by reacting chlorine gas decomposed at temp. equal to or higher than the decomposition temp. of a chlorine component with a dechlorination agent. SOLUTION: When a plastic material is heat-treated, a dechlorination agent composed of a carbonate type alkali substance is added. Harmful chlorine gas generated at a time of heat treatment is reacted with the dechlorination agent and, for example, when sodium bicarbonate (NaHCO3 ) is added, it is reacted with hydrogen chloride (HCl) according to the reaction formula (NaHCO3 )+(HCl) → (NaCl)+(H2 O)+(CO2 ). If there are Na and CO components, a chlorine component becomes NaCl becoming a part of residue, moisture (H2 O) and gaseous CO2 , and chlorine gas being a cause of dioxine is not formed and the detoxification of exhaust gas and residue can be realized and reutilization becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to detoxify harmful chlorine-based gas generated when heat-treating a plastic material (plastic waste, etc.) which generates a large amount of chlorine-based gas by heating, and The present invention relates to a method for dechlorinating a plastic material that produces harmless chlorides.

[0002]

2. Description of the Related Art Conventionally, objects to be treated, such as plastic waste materials, which generate a large amount of chlorine-based gas (hydrogen chloride gas, chlorine gas) by heating, are incinerated in an incinerator or the like. At the time of this incineration, chlorine-based gas is generated. For the purpose of suppressing generation of chlorine-based gas, dechlorinated substances such as slaked lime and calcium carbonate are added.

[0003] In addition, after the object to be treated is incinerated in an incinerator, it is further subjected to various exhaust gas removal treatments (secondary combustion, bag filter, etc.) as necessary, so that harmful chlorine-based gas is removed from the atmosphere. To prevent it from being released.

[0004] Such a technique is disclosed, for example, in Japanese Patent Publication No. 2-10
341 and Japanese Patent Publication No. 4-68532.

[0005]

The problem with such incineration of plastic waste is the treatment of chlorine components contained in plastic materials, and the chlorine-based gas gasified during the incineration process. This may cause problems such as damaging the incinerator itself, corroding the steam pipe, and generating dioxin.

Accordingly, the generated chlorine-based gas is reacted with slaked lime or the like by a bag filter or the like so that the chlorine-based gas is not discharged into the atmosphere.

However, although a certain effect can be expected by purifying the gas after the incineration, it is difficult to completely remove the gas because it remains in the residue even if it can be prevented from diffusing into the atmosphere. At present, it is a cause of dioxin generation.

In addition, in the treatment process, slaked lime or calcium carbonate is generally added to suppress the generation of chlorine-based gas, but at present it is not enough.

[0009] Therefore, it is desired to quickly establish a technique for removing or preventing the generation of chlorine-based gas that causes dioxin.

[0010]

Means for Solving the Problems The inventors of the present invention have:
As a result of various experimental investigations, when degassing the gas generated by thermally treating an object containing a large amount of chlorine components, a carbonate-based alkaline substance that reacts with chlorine-based gas (hydrogen chloride gas, chlorine gas) It has been found that by adding and treating as a dechlorinating agent, they react with each other and harmful chlorine-based gases are replaced with harmless chlorides.

The present invention has been made based on this finding, and uses a dechlorinating agent made of a carbonate-based alkaline substance as an additive, and adds a chlorine-based gas and a dechlorinating agent added in a heated low oxygen atmosphere. And by reacting the same with each other to produce harmless chlorides, thereby dechlorinating the plastic material.

According to the dechlorination treatment method of the present invention, in a low-oxygen atmosphere, a dechlorinating agent is added to an arbitrary position in a series of treatment systems from the introduction of an object to be discharged to exhaustion (exhaust and removal of residues). By supplying it, dechlorination can be performed.
In other words, in addition to the above-mentioned processing furnace, the present invention can be applied to various existing apparatuses such as flue gas and exhaust gas treatment, and incinerators.

Here, a low oxygen atmosphere means that the oxygen component is small.

That is, in the case of a heat treatment furnace, a state in which an object to be treated is charged and the atmosphere remains inside with the entrance and the exit closed.

The closure need not be completely closed,
Even if the inlet side is closed by the object to be treated, the pressure inside the furnace has increased due to heating, etc.
Almost no intrusion of outside air is allowed. Generally speaking, it is equivalent to "carbonization".

On the other hand, after the heat treatment (either in the case where the treatment is performed by supplying the dechlorinating agent of the present invention or in the case where the treatment is performed without supplying the dechlorinating agent), the heat treatment is performed in a low-oxygen atmosphere at an arbitrary position up to the discharge. It can be detoxified by supplying to the exhaust gas or the residue.

The exhaust gas detoxified by supplying the dechlorinating agent of the present invention does not contain any chlorine-based gas components, and is subjected to post-treatment (treatment such as heat treatment such as secondary combustion) for discharge. This can be done as needed. Of course, it may be discharged as it is.

As the dechlorinating agent used in the present invention, (1) a substance selected from a simple substance of a carbonate-based alkali substance, two or more simple substances, and a mixture of two or more simple substances.

(2) Carbonic acid-based sodium substance (3) A substance selected from a simple substance selected from sodium hydrogen carbonate, sodium carbonate, sodium sesquicarbonate, and natural soda, a mixture of two or more simple substances, and a mixture of two or more simple substances.

It is used by appropriately selecting from the following.

The shape of the dechlorinating agent may be any of a lump, a plate, a porous shape, a powder (powder, granules or a mixture thereof), a solution (aqueous solution, other solution) and a suspension.
In use, any one of these or a combination thereof is used, and furthermore, a solid or liquid, or an exhaust gas is charged into a material to be treated, mixed, sprayed, or used in combination or generated. React with gas.

The dechlorinating agent is used in an amount of 0.05 to 70% by weight based on the starting weight of the material to be treated. In addition, irrespective of the weight, it is added in the same amount or more as the amount of chlorine-based gas generated from the object to be treated. Alternatively, the amount to be added is selected so as to be equal to or less than the allowable chlorine gas emission standard.

The dechlorinating agent may be added at a temperature lower than the thermal decomposition temperature of the chlorine component (mixed from the beginning), during thermal decomposition (spraying during heating), or after thermal decomposition (dry distillation gas, exhaust gas). Or the combination is appropriately added. The heat treatment temperature is 1 degree from the decomposition temperature of the chlorine component (200 ° C to 300 ° C).
000 ° C.

When a heat treatment is performed by adding a dechlorinating agent to the object under the above conditions, for example, when sodium hydrogen carbonate (NaHCO ₃ ) is added, hydrogen chloride (HC
l) reacts with:

(NaHCO ₃ ) + (HCl) → (NaC
l) + (H ₂ O) + (CO ₂ ) From this, if there are Na and CO components, the chlorine component becomes
It becomes NaCl, water (H ₂ O), and gaseous CO _{2 as} a part of the residue, and does not generate a chlorine-based gas contributing to the cause of dioxin.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When an object to be treated containing all or a part of a plastic material is heat-treated in a low-oxygen atmosphere, a carbonate-based alkali substance is added as a dechlorinating agent. By adding the dechlorinating agent and heating, the chlorine component contained in the object to be treated is decomposed at a predetermined temperature, and the harmful chlorine-based gas generated by the decomposition reacts with the dechlorinating agent. To produce harmless chlorides.

[0027] The carbon dioxide-based alkali substance of the dechlorinating agent is formed by replacing harmful chlorine-based gas with harmless chloride.
The following experimental investigation revealed this.

In the experiment, a low-oxygen atmosphere was created in a closed vessel with an exhaust pipe and a door, and a sample was placed in the closed vessel, heated in an electric furnace, and heated from 250 ° C to 600 ° C.
The temperature was maintained at 0 ° C. intervals for 5 minutes at each temperature, and the concentration (ppm) of hydrogen chloride gas (HCl) was measured when the temperature was raised and when the temperature was kept.

The gas concentration was measured using a detector tube specified in JIS-K0804.

Table 1 shows the measurement results. The hydrogen chloride gas concentration is a measured value in ten experiments, Examples 1 and 2 show the highest values, and Comparative Examples 1 to 3 show the lowest values.

Note that "ND" represents "not detected",
It shows that none was detected in 10 experiments.

[0032]

[Table 1]

In the experiment, first, a preliminary test was performed using only polyvinylidene chloride containing a large amount of a chlorine component.
The results are shown in Comparative Example 1 of Table 1.

Next, an experiment was conducted by adding powders of calcium carbonate and slaked lime, which are conventionally known as dechlorinating agents. The results are shown in Comparative Examples 2 and 3.

Next, an experiment was conducted by selecting sodium bicarbonate from the dechlorinating agent for a carbonate-based alkali substance of the present invention. The results are shown in Example 2.

Further, using vinyl chloride as an object to be treated,
The experiment was performed with the addition of sodium bicarbonate powder. The results are shown in Example 1.

The following is considered from the experimental results shown in Table 1.

First, when polyvinylidene chloride containing a large amount of a chlorine component is used as an object to be treated, a large amount of hydrogen chloride gas is generated over various temperatures due to heat treatment in Comparative Example 1 in which a dechlorinating agent is not added. . In Comparative Example 2 in which calcium carbonate as a conventional dechlorinating agent was added to the object to be treated, and in Comparative Example 3 in which slaked lime was added, generation of hydrogen chloride gas was considerably suppressed as compared with Comparative Example 1. Not yet enough.

On the other hand, in Example 2 in which sodium hydrogencarbonate was added as a dechlorinating agent to the object to be treated, hydrogen chloride gas was not detected over the entire temperature range, and very good results were obtained.

In addition, even when sodium chloride is added using vinyl chloride as an object to be treated, as shown in Example 1, the production of hydrogen chloride is completely suppressed in any temperature range.

Thus, when a plastic material is dechlorinated by thermal treatment, it reacts with chlorine-based gas.
It has been found that harmless treatment can be achieved by adding a carbonate-based alkali substance (especially a sodium-based substance) as an additive.

According to the above experimental investigation, when a plastic material containing a chlorine component is thermally treated, a carbonate-based alkali substance (particularly, a sodium-based) reacting with a chlorine-based gas.
It was confirmed that the detoxification treatment can be performed by adding and treating as an additive.

Although the same effect was obtained by conducting experiments at a temperature of 600 ° C. or higher, the maximum temperature is preferably 1000 ° C. in consideration of the fact that the equipment becomes larger at higher temperatures.

When a carbonic acid-based alkali substance, in particular, a sodium-based substance reacts with a chlorine-based gas, the detoxification of exhaust gas and residues can be realized as follows. By being generated.

(1) In the case of sodium hydrogen carbonate When sodium hydrogen carbonate (NaHCO ₃ ) is added, it reacts with aqueous chloride (HCl) to give the following.

(NaHCO ₃ ) + (HCl) → (NaC
l) + (H ₂ 0) + (CO ₂ ) When water is present (NaHCO ₃ ) + (H ₂ O) → (NaOH) + (H ₂ C)
O ₃ ) (NaOH) + (H ₂ CO ₃ ) + (HCl) → (NaC
1) + (H ₂ O) + (CO ₂ ).

(2) In the case of sodium carbonate When sodium carbonate (Na ₂ CO ₃ ) is added, it reacts with hydrogen chloride (HCl) to give the following.

(Na ₂ CO ₃ ) + (2HCl) → (2Na
Cl) + (H ₂ O) + (CO ₂ ) (3) In the case of sodium sexquicarbonate represented by the chemical formula Na ₂ CO ₃ .NaHCO ₃ .2H ₂ O, the same reaction as in the above (1) and (2) Then, harmful hydrogen chloride (HCl) is replaced with harmless chloride (NaCl) to generate.

When the obtained residue was analyzed, no harmful chlorine-based gas component was detected, and harmless chloride, sodium chloride (NaCl), was detected. Further, the residue was
By washing with water while stirring for a minute, sodium chloride was dissolved in water and carbide remained, but no chlorine-based gas component was detected in the carbide.

Therefore, the chlorine component becomes sodium chloride (NaCl), which is a part of the residue, water (H ₂ O), and gaseous CO ₂ , and it is difficult to generate hydrogen chloride which is a cause of dioxin. Harmless exhaust gas and residue can be realized.

From the above, the following substances showing the same reaction as described above can be used as the dechlorinating agent.

(1) A substance selected from a simple substance of a carbonate-based alkali substance, two or more kinds of simple substances, and a mixture of two or more simple substances.

(2) Carbonic acid-based sodium substance (3) A substance selected from a simple substance selected from sodium bicarbonate, sodium carbonate, sodium sesquicarbonate, and natural soda, a mixture of two or more simple substances, and a mixture of two or more simple substances .

Note that sodium hydrogen carbonate (NaHC)
O ₃ ) is also referred to as (a) sodium acid carbonate (b) sodium bicarbonate (c) sodium bicarbonate, and is also commonly referred to as baking soda.

As another name, sodium carbonate (Na ₂ CO ₃ ) is called sodium carbonate, or simply soda. Further, anhydrous salt is also called soda ash, and decahydrate is also called washing soda or crystal soda.

Sodium sequicarbonate (Na ₂ CO ₃ .Na
HCO ₃ .2H ₂ O) is also referred to as (a) sodium monohydrogen dicarbonate (b) sodium sodium bicarbonate (c) sodium sesquicarbonate, and is naturally produced as trona (natural soda).

On the other hand, NaCl is produced by the reaction, and the produced NaCl is a harmless chloride.
Cl can be effectively removed by a washing treatment with a solution such as water, and after washing, a reusable carbonized substance remains.

Therefore, depending on the characteristics of the residue, the residue can be separated into various substances by a separation means or the like, and the separated substance can be dried and solidified to be used effectively as fuel or other materials.

Since the treatment liquid after washing contains almost no harmful substances, it can be discharged directly to rivers or oceans.

The residual chlorine component in the solidified residue was measured by ion chromatography to find that
What was ppm was 5 ppm or less, which was almost equal to nothing.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual view of a first embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a tank, which is made of, for example, an iron-based material (preferably a magnetic material) and which can be opened and closed freely. Having. Reference numeral 13 denotes a heating source, which is formed in a cylindrical or rectangular tube shape to constitute a heating source, and into which the tank 11 is inserted. The tank 21 is heated by supplying electric power to the heating source 13. 14 is an exhaust pipe, 15 is a valve, 16 is a pump, and 17 is a gas container.

In the heat treatment of the object to be treated, the plastic material of the object to be treated and the dechlorinating agent are filled in a tank, sealed with a sealing lid to shut off the outside air, and the tank is placed in a heating source installed in advance. When the heating source is an electric furnace, power is supplied to heat the entire tank, and the object to be treated is carbonized. Then, after the heat treatment for a predetermined time, the tank is taken out of the heating source and cooled, the gas in the tank is drawn out, and the residue in the tank is taken out.

The gas may be extracted by taking out the tank immediately after taking out the tank from the heating source and then cooling it. Alternatively, the gas may be extracted while being gradually heated by the heating source.

By this dry distillation treatment, the chlorine component in the object to be treated is decomposed to generate harmful chlorine-based gas. At this time, it reacts with a dechlorinating agent composed of a carbonic acid-based alkali substance to produce harmful chlorine-based gas. Gas (HCl) is harmless chloride (NaC
Substitution is generated in l).

The heating source may be any of electric heating, combustion heating, gas heating, microwave heating, induction heating and the like, or a combination thereof.

FIG. 2 is a conceptual diagram of a second embodiment of the present invention, showing a case where a plastic material is heat-treated in a heat treatment furnace. A plastic material or an object to be treated containing a large amount of plastic material is charged into a heat treatment furnace 20 from a plastic material charging hopper 21. When the plastic material is charged, the dechlorinating agent is supplied from the dechlorinating agent supply unit 22 and mixed with the object to be processed in the mixing unit 23. The mixing of the dechlorinating agent may be performed in the plastic material input hopper 21, or may be supplied to the heat treatment furnace 20 without the mixing unit 23 by a different route from the plastic material.

When the object to be treated and the dechlorinating agent are dry-distilled in the heat treatment furnace 20, the chlorine-based gas decomposed at a temperature higher than the decomposition temperature of chloride reacts with the dechlorinating agent to cause harmful chlorine-based gas. Are produced by substitution with harmless chlorides. Therefore, since no harmful chlorine-based gas is present in the generated gas, the exhaust heat may be used as it is in the heat exchanger 24 and then discharged to the atmosphere from the chimney 25 or temporarily stored in the gas container 26. Alternatively, it can be used as fuel as it is, and further used as heating gas for heating or the like.

Reference numeral 27 denotes a hot water supply system which circulates a liquid such as water in the heat exchanger 24 and uses it as hot water.

On the other hand, the processing ash (residue) processed in the heat processing furnace 20 is taken out to the processing ash extracting section 28. Harmless chloride (sodium chloride) is generated and present in the treated ash, but the harmless chloride can be easily washed and removed with water or the like. Alternatively, it can be solidified and used as fuel, and does not require complicated dechlorination equipment as in the past.

[0071]

As described above, according to the present invention, when a plastic material which generates a chlorine-based gas by heating is heated, a chlorine-containing component is decomposed by adding a dechlorinating agent made of a carbonic acid-based alkali substance. Since the chlorine-based gas decomposed at a temperature higher than the temperature reacts with the dechlorinating agent to replace and generate harmful chlorine-based gas with harmless chloride, the following effects are obtained.

(1) Harmless exhaust gas containing no harmful chlorine-based gas can be obtained, and even if released directly into the atmosphere, it conforms to the Air Pollution Control Law and does not generate dioxins.

Further, since the desalted gas is harmless, it can be reused as it is for various uses such as fuel for a gas engine, a heat source for a water heater, and a heating gas for heating or the like.

(2) It can be applied without any change to existing treatment equipment, and is more efficient than conventional slaked lime dechlorinating agents used in existing equipment, and can be dechlorinated with a small amount of use. Can be realized.

(3) Harmless chloride (Nac) is contained in the residue.
Although l) is produced and present, this harmless chloride can be easily removed by washing with a solution such as water.

Further, since the treated liquid after washing contains no harmful substances, it can be discharged to rivers and oceans as it is.

It is, of course, optional to take measures to remove other harmful substances.

Most of the material after cleaning is carbide, and can be effectively reused as fuel.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Tank 12 ... Opening / closing lid 13 ... Heating source 14 ... Exhaust pipe 15 ... Valve 16 ... Pump 17 ... Gas container 20 ... Heat treatment furnace 21 ... Plastic material charging hopper 22 ... Dechlorinating agent supply part 23 ... Mixing part 24 ... Heat Exchanger 25: Chimney 26: Gas container 27: Hot water supply facility 28: Processing ash extraction unit.

Claims (12)

[Claims] 1. A dechlorination method for a plastic material which generates a large amount of harmful chlorine-based gas by heating, wherein the harmful chlorine-based gas and a dechlorinating agent comprising an added carbonate-based alkali substance are heated. A method for dechlorination of plastics, characterized in that harmful chlorine gas is replaced with harmless chloride by reacting in a low oxygen atmosphere. 2. The dechlorination treatment of a plastic material according to claim 1, wherein the dechlorination agent is selected from a mixture of a simple substance of a carbonate-based alkaline substance, two or more simple substances, and a mixture of two or more simple substances. Method. 3. The method according to claim 1, wherein the dechlorinating agent is a carbonate-based sodium substance. 4. The dechlorinating agent is selected from a simple substance selected from sodium hydrogen chloride, sodium carbonate, sodium sesquicarbonate and natural soda, a mixture of two or more simple substances, and a mixture of two or more simple substances. The method for dechlorination of a plastic material according to claim 1. 5. The dechlorinating agent may be in the form of a block, a plate, a porous,
The method for dechlorination of plastic material according to any one of claims 1 to 4, wherein the method is formed in any of a powder, a solution, and a suspension. 6. The plastic material according to claim 1, wherein the dechlorinating agent is added in an amount of 0.05 to 70% by weight based on the starting weight of the material to be treated. Dechlorination treatment method. 7. The method for dechlorinating plastic material according to claim 1, wherein the dechlorinating agent to be added is added in an amount equal to or more than the same amount as the amount of chlorine-based gas generated by the object to be treated. 8. The method according to claim 1, wherein the dechlorinating agent is added at a time lower than the thermal decomposition temperature of the chlorine component contained in the plastic material, or during or after the thermal decomposition, or in combination. The method for dechlorination of plastic material according to 1. 9. The plastic material according to claim 1, wherein the chlorine agent to be added is added so as to have an emission amount of a chlorine-based gas which meets an allowable emission standard or less. Dechlorination treatment method. 10. The dechlorination treatment of a plastic material according to claim 1, wherein the use of the dechlorinating agent is any of charging, mixing, and spraying, or a combination thereof. Method. 11. The method according to claim 1, wherein the means for thermally decomposing the chlorine component is dry distillation. 12. The method for dechlorinating plastic material according to claim 1, wherein a temperature range of the heat treatment in a low oxygen atmosphere is 200 ° C. to 1000 ° C.