JPH10235186A - Dechlorination agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dechlorination agent reacting with a component such as harmful chlorine gas generated when a material to be treated containing a chlorine component is thermally treated to form harmless gas and forming chloride free from a harmful component even in residue. SOLUTION: A dechlorination agent is fundamentally constituted of a carbonate type alkali substance reacting with chlorine gas in a heated low oxygen atmosphere to form harmless chloride. This dechlorination agent is selected from a carbonate type alkali substance alone, two or more kinds of carbonate type alkali substances and a mixture, of those alkali substances. Concretely, a dechlorination agent selected from a sodium carbonate single substance alone, two or more kinds of sodium carbonate type single substances and a mixture of those sodium carbonates. Corresponding to a use purpose, the dechlorination agent is brought into contact with chlorine gas in either one of lumpy, plate- shaped, porous, powdery, soln. and suspension forms.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chlorine-based gas (hydrogen chloride gas, chlorine gas) generated by heat-treating an object to be treated containing a chlorine component, for example, waste such as municipal waste or an industrially treated material. And a dechlorinating agent which produces a harmless gas and chloride by reacting with the dechlorinating agent.

[0002]

2. Description of the Related Art Recently, the amount of waste such as municipal garbage has been increasing year by year, and its disposal has become a problem. These municipal wastes are discharged as waste from ordinary households and offices, and are mainly combustible. These combustible wastes contain a wide variety of chemical substances, such as plastics containing a large amount of vinyl chloride resin and substances containing a large amount of chlorine, such as chlorine bleach for paper used in offices. ing.

[0003] As a means for treating these wastes, incineration is generally widely used. However, when an object to be treated containing a chlorine component is incinerated, chlorine gas (hydrogen chloride gas, chlorine gas) is generated by the incineration, causing problems such as environmental pollution and deterioration of the incineration facility due to the chlorine gas. For the purpose of suppressing the generation of such chlorine-based gas, there has been conventionally known a method of incineration treatment by adding a dechlorinating agent such as slaked lime or calcium carbonate.

[0004] Further, after the object to be treated put in the treatment furnace is incinerated, if necessary, purification treatment of various exhaust gases, for example, reaction with slaked lime by a bag filter does not release harmful chlorine-based gas into the atmosphere. Means for doing so are also known.
Such a technique is disclosed in Japanese Patent Publication No. 2-10341.

[0005]

A problem that arises when incinerating waste or the like is chlorine components such as chlorides and chlorine compounds contained in the material to be treated, which are generated during the incineration process. Chlorine-based gas damages the processing furnace itself, corrodes the steam pipe, and further causes problems such as generation of 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 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. And contribute to the generation of dioxin.

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.

Accordingly, the present invention provides a harmless gas by reacting with a harmful chlorine-based gas or the like generated by thermally treating an object to be treated, and a harmless gas containing no harmful components in the residue. It is an object of the present invention to provide a dechlorinating agent which produces chloride and can be used in any of various apparatuses such as a heat treatment furnace and an exhaust gas treatment.

[0011]

Means for Solving the Problems The inventors of the present invention have:
As a result of various experimental investigations, when chlorine-containing gas generated by thermally treating an object containing a large amount of chlorine components such as chlorides and chlorine compounds is dechlorinated, chlorine-based gas (hydrogen chloride gas, chlorine gas ) Was added and treated as an additive, thereby reacting with each other, and it was found that harmful chlorine gas was replaced with harmless chloride.

The present invention has been made based on this finding. By using a dechlorinating agent composed of a carbonate-based alkaline substance as an additive, the dechlorination added to a chlorine-based gas in a heated low-oxygen atmosphere is performed. Provided is a dechlorinating agent that can react with a chlorine agent to generate harmless chloride.

The supply point of the dechlorinating agent of the present invention is supplied at an arbitrary position in a series of processing systems from the introduction of the object to be discharged to the discharge (exhaust of smoke and removal of the residue) in a low oxygen atmosphere. be able to. Therefore, the present invention can be applied not only to the treatment furnace but also to various existing facilities such as a flue or exhaust gas treatment and an incinerator.

Here, the low oxygen atmosphere means that the oxygen component is small. In other words, in the case of a heat treatment furnace, a state in which an object to be treated is charged and the air remains inside with the inlet and outlet closed is allowed.

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.

The dechlorinating agent of the present invention is selected from (1) 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 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. To use as appropriate.

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. . At the time of use, use any of these or a combination of these, and further, charge, mix, spray, or use a solid or liquid or exhaust gas to be treated, or generate a gas And react with.

The amount of the dechlorinating agent used is preferably 0.05 to 10% by weight based on the starting weight of the material to be treated, but the material to be treated may be vinyl chloride, vinylidene chloride, synthetic resin, rubber,
When a chlorine component is contained in a large amount as in the case of, for example, 10 to 70% by weight of the starting weight is added. Alternatively, it is added in an amount equal to or more than the amount of chlorine-based gas generated from the object to be treated regardless of its weight. Alternatively, the addition amount is selected so as to be below the allowable chlorine gas emission standard.

The dechlorinating agent may be added at a temperature below the thermal decomposition temperature of the chlorine component (mixed from the beginning), during thermal decomposition (spray during heating), or after thermal decomposition (dry 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.

Under the above conditions, when a dechlorinating agent is added to the object to be treated and heated, for example, when sodium hydrogen carbonate (NaHCO ₃ ) is added, hydrogen chloride (HC
l) reacts with: (NaHCO ₃ ) + (HCl) → (NaCl) + (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.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When heat-treating an object containing a chlorine-based substance which generates a chlorine-based gas by heating, 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.

Hereinafter, based on specific examples, the results of an experiment on dechlorination of an object to be treated using the dechlorinating agent of the present invention will be described together with the experimental results of a comparative example.

1. [Dechlorination Treatment Using Polyvinylidene Chloride] A dechlorination experiment was conducted using polyvinylidene chloride containing a large amount of a chlorine component as an object to be treated. In the experiment, as shown in Table 1, Example 1 in which 20 g of sodium bicarbonate was added as a dechlorinating agent to each 4 g of the object to be treated, Comparative Example 1 in which no dechlorinating agent was used, and 20 g of slaked lime as a dechlorinating agent were used. The test was performed using each sample of Comparative Example 2 used and Comparative Example 3 using 20 g of calcium carbonate as a dechlorinating agent. Powder having an average particle size of 100 μm was used as a dechlorinating agent.

[0026]

[Table 1]

2. [Dechlorination treatment of objects to be treated simulating standard municipal waste] To simulate standard municipal waste and create a more severe situation, add the above-mentioned polyvinylidene chloride to the simulated trash to create an object to be treated. To conduct a dechlorination experiment. At the same time, water was added to the municipal waste and a dechlorination experiment was performed in the same manner.

As shown in Table 2, as shown in Table 2, 20 g of simulated garbage was treated with 1 g of polyvinylidene chloride, and 5 g of sodium bicarbonate was added as a dechlorinating agent to the material to be treated. Example 3 in which 2.5 g of sodium bicarbonate was added to the material to which 0.5 g was added, and Example 3 in which 0.5 g of sodium hydrogen carbonate was added to the material to be processed in which 0.1 g of polyvinylidene chloride was added to 20 g of simulated waste. Example 4 and Example 5 in which 5 g of sodium bicarbonate was added to an object to be treated in which 20 cc of water was added to 20 g of simulated waste.
Was carried out using each sample.

[0029]

[Table 2]

The simulated standard municipal garbage is obtained by crushing the following components.

20% by weight ・ Plastic (PE, PP, PS, PVDC) 50% by weight ・ Paper (tissue, newspaper, wrapping paper, box, beverage pack) 20% by weight ・ 10% by weight of cloth (such as cloth) ・ Kitchen above Each of the samples of Examples 1 to 5 and Comparative Examples 1 to 3 was put in a tank, sealed after adding a predetermined dechlorinating agent, and after shutting off the outside air, the tank was heated using a heating coil. Each sample was prepared at 250 ° C, 300 ° C, 350 ° C, 40 ° C shown in Table 3.
The temperature was divided into eight stages of 0 ° C., 450 ° C., 500 ° C., 550 ° C., and 600 ° C., held at each temperature for 5 minutes, and the hydrogen chloride gas concentration was measured at the time of temperature rise and at the time of keeping. Measurement of gas concentration is J
The measurement was performed using a detector tube specified in IS-K0804.

Table 3 shows the measurement results. The hydrogen chloride gas concentration is a measured value in ten experiments, and Examples 1 to 5 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.

[0034]

[Table 3]

From the above experimental results, it has been clarified by an experiment that a carbonic acid-based alkali substance as a dechlorinating agent replaces harmful chlorine-based gas with harmless chloride. In the experiment, first, a preliminary test was performed using only polyvinylidene chloride containing a large amount of a chlorine component. As a result, as shown in Comparative Example 1 in Table 3, it was found that a large amount of hydrogen chloride was generated by the heat treatment.

Next, an experiment was conducted by adding slaked lime and calcium carbonate, which are conventionally known as dechlorinating agents. As a result, as shown in Comparative Examples 2 and 3, it was found that although the production of hydrogen chloride was considerably suppressed, it was not yet sufficient.

Therefore, as a result of various studies and deliberation, an experiment was conducted by selecting sodium bicarbonate, focusing on a carbonate-based alkaline substance. Very good results were obtained as shown in Examples 1 to 5 in Table 3.

As a result, it was found that the production of hydrogen chloride was completely suppressed in any temperature range, and it was found that sodium hydrogen carbonate was the most effective substance as a dechlorinating agent.

Thus, when dechlorinating a chlorine gas generated from an object to be treated, a harmless treatment can be achieved by adding a carbonate-based alkali substance (particularly a sodium-based) which reacts with chloride as an additive. I found that I can do it.

3. [Consideration of Results] The results shown in Table 3 are considered as follows. 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 each temperature due to the heat treatment in Comparative Example 1 in which the dechlorinating agent is not added. In Comparative Example 2 in which slaked lime as a conventional dechlorinating agent was added to the object to be treated, and in Comparative Example 3 in which calcium carbonate was added as a dechlorinating agent, generation of hydrogen chloride gas was considerably suppressed as compared with Comparative Example 1. But still not enough.

On the other hand, in Example 1 in which sodium hydrogencarbonate was added as a dechlorinating agent to the above-mentioned object, hydrogen chloride gas was not detected over the entire temperature range, and very good results were obtained. Further, in the case of Example 2.3.4 in which the amount of sodium bicarbonate added as a dechlorinating agent was changed for the object to be treated in which polyvinylidene chloride was added to the simulated garbage, over the entire temperature range. No hydrogen chloride gas was detected.

In the case of the fifth embodiment in which sodium bicarbonate was added to the simulated object by adding moisture to the simulated garbage, the temperature was raised at 450 ° C., kept at 450 ° C., and kept at 5 ° C.
Although a slight generation of hydrogen chloride gas was observed when the temperature was raised to 00 ° C., it was almost completely unaffected even in the presence of moisture, and was compared with Comparative Example 2 using slaked lime as a dechlorinating agent. Very good results were obtained.

According to the above experimental investigation, when a substance containing a chlorine component is thermally treated, a harmful treatment can be achieved by adding a carbonate-based alkali substance (particularly, a sodium-based substance) reacting with the chlorine component as an additive. I can confirm that I can do it.

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

When a carbonate-based alkali substance, particularly a sodium-based substance, reacts with chloride, the harmlessness of exhaust gas and residue can be realized because harmful chloride is replaced with harmless chloride as follows. It depends.

(1) In the case of sodium hydrogen carbonate When sodium hydrogen carbonate (NaHCO ₃ ) is added, it reacts with hydrogen chloride (HCl) to give the following. (NaHCO ₃ ) + (HCl) → (NaCl) + (H
₂₀ ) + (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 carbon dioxide (CO ₂ ), and hydrogen chloride which is a cause of dioxin is converted. There is no generation, and detoxification of exhaust gas and residues 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, 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 properties 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 as fuel or other effective material.

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

Next, sodium chloride (NaCl), which is a harmless chloride, is produced in the residue taken out of the tank. In order to remove the carbide, the residue is placed in a water tank and stirred for a predetermined time to dissolve sodium chloride in water. Next, this is separated by dehydration, dried and solidified. The separated wastewater is treated by separate wastewater treatment means.

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

[0061]

As described above, by using the dechlorinating agent according to the present invention, no chlorine-based gas is generated over the entire temperature range as compared with the conventional dechlorinating agent using slaked lime or calcium carbonate. In addition, it produces a chloride having no harmful components in the residue, and can exhibit a sufficient function as a dechlorinating agent, particularly for an object to be treated containing a large amount of a chlorine component such as municipal waste.

The dechlorinating agent according to the present invention reacts with a chlorine-based gas in a heated low-oxygen atmosphere to produce harmless gas and chloride, and is discharged from a heat treatment furnace (smoke exhaust,
Until the removal of the residue), it can be used in any department in a series of processing steps. In other words, the flue,
The present invention can be applied to various existing devices such as an exhaust gas treatment device and an incinerator.

Further, even after the object to be treated is subjected to a heat treatment irrespective of the addition or non-addition of a dechlorinating agent, the dechlorinated gas of the present invention is added to the exhaust gas or residue in a low oxygen atmosphere at any point up to the discharge. The agent can be supplied for detoxification treatment.

At the time of application, damage to the processing furnace or incinerator itself due to chlorine-based gas and corrosion of the steam pipe are prevented, so that the life of the apparatus and the facility is prolonged. Dioxin is not generated, and safety on the environment and in treating residues is improved.

Further, even in the case of an object to be treated containing water, it is hardly affected in function.

Since no harmful chlorine-based gas is present in the exhaust gas, secondary combustion can be carried out as a post-treatment means for the exhaust gas, if necessary.

Claims (5)

[Claims] 1. A dechlorinating agent that reacts with a harmful chlorine-based gas in a heated low oxygen atmosphere, wherein the dechlorinating agent reacts with the harmful chlorine-based gas to form a harmless chloride. Become a dechlorinating agent. 2. The dechlorinating agent according to claim 1, wherein the dechlorinating agent is selected from a mixture of a simple substance of a carbonate-based alkali substance, two or more simple substances, and a mixture of two or more simple substances. 3. The dechlorinating agent according to claim 1, wherein the dechlorinating agent is selected from a simple substance of a carbonate-based sodium substance, two or more simple substances, and a mixture of two or more simple substances. 4. As a dechlorinating agent, sodium hydrogen carbonate,
The dechlorinating agent according to claim 1, wherein the dechlorinating agent is selected from a simple substance selected from sodium carbonate, sodium sesquicarbonate, and natural soda, a mixture of two or more simple substances, and a mixture of two or more simple substances. 5. The dechlorination agent according to claim 1, wherein the dechlorination agent is brought into contact with a harmful chlorine-based gas in any state of a lump, a plate, a porous form, a powder, a solution, and a suspension. Chlorine.