JPH10237509A - Operation of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems as the necessity of a working equipment for pulverizing a synthetic resin into granular state or powdery state capable of being blown from a tuyere under carriable condition with the air as the pre-treatment to supply the synthetic resin as auxiliary fuel into a blast furnace, and the necessity of separating treatment of plastics, etc., in the case of using the plastics contained in the treated material of municipal waste and the treatment of chlorine base gas generated in a heating process. SOLUTION: Dechlorinating agent composed of an alkali metal hydroxide reactive with a harmful chlorine base gas and in a heated low-oxygen atmosphere, is added and reacted with the chlorine base gas and harmless chloride compounds are produced to execute the dechlorinating treatment, and the chlorine base gas as one factor of causing of dioxin is removed, and the harmlessness of both the exhaust gas and the residue is realized and this harmless gas is blown as the auxiliary fuel from a tuyere 15. As the dechlorinating agent, one or more kinds of single bodies or mixture of two or more kinds of single bodies selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide and cesium hydroxide, are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a blast furnace, and more particularly to a method for heating an object to be treated, such as waste containing chlorine components such as chlorine and chlorine compounds, to remove harmful chlorine gas generated at this time. The present invention relates to a method for operating a blast furnace, wherein the blast furnace is made harmless by reacting with a dechlorinating agent, and is blown from a tuyere of the blast furnace as an auxiliary fuel to be used as fuel.

[0002]

2. Description of the Related Art Conventionally, in a blast furnace, as an auxiliary fuel for coke, heavy oil or pulverized coal has been blown from a tuyere of the furnace to produce pig iron or the like.

[0003] In recent years, as this auxiliary fuel, synthetic resin waste (waste) such as plastic has been pulverized into granular or powdery form and injected into heavy oil, or directly blown into a tuyere to treat municipal waste. Technologies for effective use of resources have been developed. (Example: JP-A-7-228905, JP-B-51-33493) FIG. 2 is a conceptual diagram showing a method of operating a blast furnace using this plastic waste as an auxiliary fuel for pulverized coal. The plastic waste as a raw material is put into the receiving hopper 1, where drying is also performed to remove moisture. This receiving hopper part 1
The plastic waste supplied from is crushed in the crushing unit 2,
In the sieving section 3 in the next step, the particles are sieved to a preset particle size, and the particles having the set particle size are sent to the plastic powder supply hopper 4 and stored. Particles larger than the set particle size are returned from the sieving unit 3 to the crushing unit 2 again, and crushed again. The plastic powder stored in the supply hopper 4 is sent to the transport pipe 6 via the flow rate adjusting unit 5.

On the other hand, pulverized coal is stored in a hopper 7 for pulverized coal, and is sent to a transport pipe 6 via a flow rate adjusting unit 8. The carrier air is supplied to the carrier pipe 6 from the pneumatic pressure source 9 at a predetermined air volume and speed, and the plastic powder is mixed with the pulverized coal and the powder is distributed to each tuyere by the powder distributor 10. Then, a plurality of nozzles 13 inserted into the blast furnace air blow pipe 12 through the transfer pipe 11 are blown into the blast furnace 14 at high speed through tuyeres 15 provided in the blast furnace 14, and are burned in the combustion zone of the blast furnace. .

[0005]

In order to supply a synthetic resin to a blast furnace as an auxiliary fuel, as a pre-treatment, the synthetic resin is separated from waste and pulverized so that air can be conveyed. It is necessary to process it so that it can be blown from the mouth. For example, it is necessary to pulverize and granulate to a granular form (0.5 to 5 mm) or a powder form (less than 5 mm), and the processing requires a large-scale machine and the work is complicated.

Since the temperature of the tuyere is considerably high, the fine synthetic resin may melt and block the tuyere. In order to prevent this, it is necessary to supply at a considerably high pressure and at a high speed, and a very large supply means is required.

[0007] On the other hand, in the case of effectively utilizing garbage such as municipal waste, the to-be-treated material such as municipal garbage is generally discharged not only from industrial waste but also from general households and offices. However, there is a problem that it is troublesome because it is necessary to select a synthetic resin such as a plastic from these.

Accordingly, an object of the present invention is to provide a technique in which an object to be treated containing combustible municipal waste other than plastic is heated without being sorted, and a gas generated at this time can be used as an auxiliary fuel for a blast furnace. It is assumed that.

[0009]

In general, municipal garbage is discharged as an object to be treated from general households or offices, and is mainly combustible. This combustible material contains a large variety of chemical substances, for example, a large amount of chlorine components such as chlorine bleach for plastics containing a large amount of vinyl chloride resin and paper used in offices. The substance is mixed.

Therefore, it is impossible to incinerate these objects as they are and to use the combustion gas generated during the incineration as fuel for the blast furnace.

As a method of dechlorinating the combustion gas generated during the heat treatment, the generated gas is treated by various means.
For example, although emphasis is placed on cleaning treatment such as adsorption treatment with a filter or the like, it is difficult to completely remove it.

The inventors of the present application have found that, as a result of various experiments and investigations, when degassing a gas generated by thermally treating an object containing a large amount of chlorine components, a chlorine-based gas (hydrogen chloride gas) is used. , Chlorine gas) as an additive, and then reacting with each other, and found that harmful chlorine-based gas is replaced with harmless chloride.

The present invention has been made based on this finding, and comprises an alkali metal hydroxide that reacts in a heated low-oxygen atmosphere with harmful chlorine-based gas generated during heat treatment of waste and the like. By adding a dechlorinating agent and reacting with the decomposed chlorine-based gas to generate harmless chloride, the harmful chlorine-based gas in the gas is removed to obtain a harmless gas. Characterized by being blown from the tuyere.

The dechlorinating agent can be supplied at an arbitrary position in a series of processing systems from the introduction of the material to be processed to the discharge (smoke emission and removal of the residue) as long as it is in a low oxygen atmosphere. .

Here, a 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, a heat treatment (either in the case where the treatment is carried out with or without the supply of the dechlorinating agent, in any case)
Thereafter, the detoxification treatment can be performed by supplying the exhaust gas or the residue in a low-oxygen atmosphere at an arbitrary position up to the discharge.

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

(2) A simple substance selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide and cesium hydroxide, 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 further mixed with, mixed with, or sprayed with a solid or liquid or a liquid to be processed, or used by a combination thereof to generate React with gas.

The dechlorinating agent is preferably used in an amount of 0.05 to 10% by weight based on the starting weight of the material to be treated. However, vinyl chloride, vinylidene chloride, synthetic resin, rubber,
When chloride 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 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 treated product under the above conditions, for example, sodium hydroxide (N
When aOH) is added, it reacts with hydrogen chloride (HCl) to give:

(NaOH) + (HCl) → (NaCl) + (H ₂ O) As described above, hydrogen chloride reacts with sodium hydroxide to form sodium chloride (NaCl), which is a part of the residue, and water (H). ₂ O), and does not generate hydrogen chloride gas which contributes to the cause of dioxin, and can make the exhaust gas and the residue harmless.

Therefore, even when used as a fuel in a blast furnace,
It does not cause air pollution by itself and can be used effectively.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram for explaining a method of operating a blast furnace according to the present invention. Note that the present invention is characterized by applying a waste treatment system instead of the conventional plastic waste supply system, and other blast furnaces and pulverized coal supply to the blast furnace are almost the same. The same reference numerals as those in 2 denote the same or corresponding parts, and a detailed description thereof will be omitted.

In FIG. 1, reference numeral 20 denotes a tank, which is made of, for example, an iron-based material (preferably a magnetic material) and has an openable / closable lid 21. Reference numeral 22 denotes a heating source, which is formed in a cylindrical shape such as a cylinder or a square tube.
Is inserted and removed. Then, the tank 20 is heated by supplying electric power to the heating source 22. 23 is an exhaust pipe with a valve, 24 is a valve, 25 is a pump, and 26 is a gas amount adjusting means.

Numerals 27 and 28 denote valves, and 29 denotes a gas storage tank.

The objects to be heated are waste, sludge,
Although any substance containing a chlorine component such as exhaust gas may be used, an example in the case of a general treatment (dust) treatment will be described.

In the heat treatment of the object to be treated, 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 this tank is inserted into a heating source 22 installed in advance. Then, electric power is supplied to the heating source to heat the entire tank, and the workpiece is subjected to dry distillation. After the heat treatment for a predetermined time, the tank is taken out of the heating source and cooled, and after the gas in the tank is extracted, the residue (processed ash) in the tank is removed.
Take out.

When the gas is extracted directly from the pulverized coal hopper 7, the gas is mixed with the pulverized coal from the pulverized coal hopper 7 by closing the valve 28, opening the valves 24 and 27, and operating the pump 25 when supplying the gas directly to the blast furnace as auxiliary fuel. , A feed pipe 11, a nozzle 13, and a blast furnace air pipe 12 to supply the blast furnace 14 from the tuyere 15.

The gas may be supplied to the transfer pipe 11 through a gas supply pipe 30 indicated by a two-dot chain line.

When the gas is temporarily stored in the gas storage tank 29, the valve 27 is closed, the valves 24 and 28 are opened, the pump 25 is operated, the gas is stored in the storage tank 19, and the valve is appropriately operated after the storage. (Opened 27 and 28) to supply as auxiliary fuel in the same manner as above.

The gas may be extracted from the tank by removing the tank from the heating source immediately after the tank is removed and then cooling the same, or may be processed while the heating source is extracting the gas little by little. In this example, the case where the heating source is electric heating is described, but any of gas heating, induction heating, combustion heating, or microwave heating may be used,
In addition, the means for pyrolysis of chlorine components is either dry distillation or incineration,
Alternatively, a combination thereof may be used.

As the dechlorinating agent to be mixed into the object to be treated, an alkali metal hydroxide is used as described later. The dechlorinating agent and the object to be treated are charged into the tank 20, and electric power is supplied to the heating source 22 for heating. When the temperature exceeds the decomposition temperature (200 ° C. to 300 ° C.) of the chlorine component, the chlorine component is decomposed, and the decomposed chlorine-based gas reacts with a dechlorinating agent composed of an alkali metal hydroxide to form a gas. Contains no harmful chlorine gas. This gas is blown from the tuyere 15 of the blast furnace 14 as auxiliary fuel.

The following experimental investigation has revealed that the alkali metal hydroxide replaces harmful chlorine-based gas in the exhaust gas with harmless chloride.

Hereinafter, the experimental results of the dechlorination of the object to be treated when the dechlorination treatment method of the present invention is applied based on the examples will be described.
This will be described together with the result of the 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, a sample in which 20 g of ground sodium hydroxide was added as a dechlorinating agent to 4 g of polyvinylidene chloride as an object to be treated was used as Example 1, and the same object was subjected to dechlorination. A sample to which 20 g of ground potassium hydroxide was added as an agent was used as Example 2. Comparative Example 1
And Comparative Example 2 are samples in which a dechlorinating agent is not added to 1 g and 4 g of the same object to be treated, Comparative Example 3 is a sample in which 20 g of slaked lime which is a conventional dechlorinating agent is added to 4 g of the same object to be treated, Comparative Example 4
Was a sample obtained by adding calcium carbonate as a dechlorinating agent to 4 g of the same workpiece. Average particle size of 100 as dechlorinating agent
A μm powder was used.

[0042]

[Table 1]

Each of the samples of Examples 1 and 2 and Comparative Examples 1 to 4 was placed in a tank, a dechlorinating agent was added thereto, the tank was sealed, the outside air was shut off, and the tank was heated by a heating means. Each sample is shown in Table 1 at 250 ° C, 300 ° C, and 350 ° C.
℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600
C. and 9 stages of 600.degree. C. to 1000.degree. C., held at each temperature for 5 minutes, and measured the concentration of hydrogen chloride gas at the time of temperature rise and at the time of keeping. The gas concentration was measured using a detector tube specified in JIS-K0804.

Table 1 shows the measurement results. The concentration of hydrogen chloride gas is the highest value in Examples 1 and 2 and the lowest value in Comparative Examples 1 to 4 as measured values in 10 experiments.

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

From the above experimental results, it has been clarified by an experiment that an alkali metal hydroxide as a dechlorinating agent replaces a harmful chlorine-based gas with a 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 Examples 1 and 2 in the table, it can be seen 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 3 and 4, it was found that although the generation 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 hydroxide and potassium hydroxide, focusing on alkali metal hydroxides. As shown in Examples 1 and 2 in Table 1, very good results were obtained.

As a result, it was found that the production of hydrogen chloride was completely suppressed in any temperature range, and that the alkali metal hydroxide was an effective substance as a dechlorinating agent.

In this way, when the chlorine-based gas generated from the object to be treated is dechlorinated, an alkali metal hydroxide which reacts with chloride is added as an additive and treated.
It has been found that harmless treatment can be performed.

2. [Consideration of Results] The results shown in Table 1 are considered as follows. First, as in Comparative Examples 1 and 2, polyvinylidene chloride containing a large amount of a chlorine component was used as an object to be treated, and when heat treatment was performed without adding a dechlorinating agent, a large amount of hydrogen chloride gas was generated over each temperature. ing. Therefore, in Comparative Examples 3 and 4 in which slaked lime and calcium carbonate, which are conventional dechlorinating agents, were added to this object and heat treatment was performed, the generation of hydrogen chloride gas was considerably suppressed as compared with Comparative Examples 1 and 2. , Not yet enough.

On the other hand, 4 g of polyvinylidene chloride as an object to be treated was mixed with 20 g of sodium hydroxide as a dechlorinating agent.
In the case of Example 1 in which 20 g of potassium hydroxide was added as the dechlorinating agent to the same workpiece,
Although slight hydrogen chloride gas generation was observed in Example 1 when the temperature was raised at 350 ° C. and 450 ° C. and in Example 2 when the temperature was kept at 450 ° C. for 5 minutes, chloride gas was generated over the entire temperature range. No hydrogen gas was detected, and very good results were obtained. Therefore, according to the present embodiment, Comparative Example 1
Very good results were obtained as compared to # 4.

From the above experimental investigations, it can be confirmed that when a substance containing chloride is thermally treated, harmless treatment can be achieved by adding an alkali metal hydroxide which reacts with a chlorine component as an additive. Was.

An experiment was conducted at a temperature of 600 ° C. to 1000 ° C., and the same effect was obtained.

When the alkali metal hydroxide reacts with the chloride, the harmlessness of the exhaust gas and the residue can be realized because the harmful chlorine-based gas is replaced with a harmless chloride as follows.

Here, when sodium hydroxide (NaOH) is used as a dechlorinating agent and added to an object to be treated, as described above, sodium hydroxide is converted to hydrogen chloride (HC).
The following reaction formula proceeds with 1).

(NaOH) + (HCl) → (NaCl) + (H ₂ O) Thus, sodium hydroxide reacts with hydrogen chloride to produce harmless sodium chloride and water.

When potassium hydroxide (KOH) is used, the reaction formula is as follows: (KOH) + (HCl) → (KCl) + (H ₂₀ ) Potassium hydroxide reacts with hydrogen chloride and is harmless potassium chloride And become water.

When the obtained residue was analyzed, no harmful chlorine gas was detected, and harmless chlorides sodium chloride (NaCl) and potassium chloride (KCl) were detected. Further, the residue was washed with water while stirring for 10 minutes, so that sodium chloride and potassium chloride were both dissolved in water, and a carbide remained, but no chlorine-based gas component was detected in the carbide.

Therefore, if the dechlorinating agent contains an alkali metal hydroxide which reacts with a chlorine component to form a harmless chloride, it becomes a part of the residue as sodium chloride or potassium chloride, which is one of the causes of dioxin generation. Hydrogen chloride, which is one of the above, is not generated, and it is possible to make these residues and exhaust gas harmless. Similar results can be obtained by using other dechlorinating agents such as lithium hydroxide, rubidium hydroxide and cesium hydroxide.

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

(1) An alkali metal hydroxide selected from a simple substance, two or more simple substances, and a mixture of two or more simple substances.

(2) A simple substance selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide and cesium hydroxide, a mixture of two or more simple substances, and a mixture of two or more simple substances.

On the other hand, NaCl and KCl are produced by the reaction, and the produced NaCl and KCl are harmless chlorides, which can be effectively removed by a washing treatment with a solution such as water, and can be reused after washing. The remaining carbonized material remains.

Therefore, depending on the characteristics of the residue, the residue can be separated into each substance 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 to rivers or oceans as it is.

Next, since harmless chlorides such as sodium chloride (NaCl) and potassium chloride (KCl) are generated in the residue taken out of the tank, the residue is put in a water tank and stirred for a predetermined time to dissolve in water. Then, the water is separated by centrifugal dehydration and drained, and the remainder is dried and solidified. The separated wastewater is treated by separate wastewater treatment means. The carbon component in the solidified residue is used as fuel, and the inorganic material can be reused as glass or cement material.

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 used effectively as a fuel or other material.

[0069]

As described above, the present invention decomposes a chlorine component contained in an object to be treated at a temperature not lower than the decomposition temperature of the chlorine component, and decomposes a harmful chlorine gas and a dechlorinating agent. Is reacted to form harmless chlorides, and harmless gas is obtained, and this gas is used as an auxiliary fuel for the blast furnace.

(1) Since harmless gas that does not contain harmful chlorine-based gas is used, effective resource recycling activities can be actually realized. Compatible and will not release dioxin from the blast furnace.

(2) Pretreatment (separation, fine pulverization) of waste is not required, which can contribute to reduction of production cost.

(3) General municipal garbage can also be subjected to heat treatment to use its exhaust gas, thereby realizing waste treatment and resource reuse (recycling), and also helping to activate the steelmaking industry. It has the effect of two birds with one stone.

(4) In addition, no harmful chlorine component is present in the residue, and harmless chloride is produced and present. This harmless chloride can be easily washed and removed with a solution such as water. .

Further, since the treated liquid after cleaning does not contain a harmful chlorine component, it can be discharged to rivers and oceans as it is.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the configuration of the present invention.

FIG. 2 is a conceptual diagram of a configuration of a conventional blast furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Receiving hopper part 2 ... Pulverizing part 3 ... Sieving part 4 ... Supply hopper 5 ... Flow rate adjusting part 6 ... Conveyance piping 7 ... Pulverized coal hopper 8 ... Flow rate adjusting part 9 ... Air generation source 10 ... Powder distributor 11 ... Conveying piping 12 ... Blast furnace blowing branch pipe 13 ... Nozzle 14 ... Blast furnace 15 ... Tuyere 20 ... Tank 21 ... Sealed lid 22 ... Heating source

Claims (10)

[Claims] An object to be treated is heat-treated to decompose a chlorine component contained in the object to be treated, and a harmful chlorine-based gas generated by the decomposition and a dechlorinating agent comprising an alkali metal hydroxide are formed. Reacts in a low-oxygen atmosphere and replaces harmful chlorine-based gas with harmless chloride to produce harmless gas.This harmless gas is blown from the tuyere of the blast furnace as auxiliary fuel. Operating method of blast furnace. 2. The method for operating a blast furnace according to claim 1, wherein said dechlorinating agent is selected from a simple substance of an alkali metal hydroxide, two or more simple substances, and a mixture of two or more simple substances. 3. The dechlorinating agent is selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, and cesium hydroxide.
The method for operating a blast furnace according to claim 1, wherein the blast furnace is selected from at least one kind of a mixture of simple substances. 4. The method according to claim 1, wherein the dechlorinating 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. The method for operating a blast furnace according to any one of claims 1 to 3. 5. The blast furnace according to claim 1, wherein the dechlorinating agent to be added is 0.05 to 10% by weight of the starting weight of the object. Operating method. 6. The dechlorinating agent to be added is 10 to 10% by weight of the starting material when the material to be treated is a substance containing a large amount of chlorine, such as vinyl chloride, vinylidene chloride, synthetic resin or rubber.
The method for operating a blast furnace according to any one of claims 1 to 4, wherein the content is 70% by weight. 7. The method for operating a blast furnace according to claim 1, wherein the dechlorinating agent to be added has the same equivalent or more as the chlorine component generated from the object to be treated. . 8. The method according to claim 1, wherein the dechlorinating agent is added so that the amount of the chlorine-based gas conforming to an allowable discharge standard is equal to or less than the discharge amount. Operating method of the blast furnace described. 9. The operation of a blast furnace according to claim 1, wherein the dechlorinating agent is added by one of charging, mixing, and spraying, or a combination thereof. Method. 10. The method for operating a blast furnace according to claim 1, wherein a temperature range of the heat treatment in the low oxygen atmosphere is 200 ° C. to 1000 ° C.