JP2003103243A - Method for treating polluted soil containing volatile organic compound, method for producing cement, and heat treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating polluted soil containing volatile organic compounds (VOC) and a method and an apparatus for producing a cement, whereby the way by which facilities, such as cement kilns, provided in a cement production plant can be effectively used to treat VOC can be developed, the heating of polluted soil and the combustion of VOC can be performed at a low cost, and a large amount of the treated detoxified soil can be effectively utilized. SOLUTION: The method for treating polluted soil comprises thermally desorbing volatile organic compounds (VOC) from polluted soil in a heating treatment apparatus, desirably, a rotary kiln or a rotary drier and burning and decomposing the separated VOC in a cement firing kiln 102.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for treating contaminated soil containing a volatile organic compound, a method for producing cement, and a heat treatment apparatus.

[0002]

2. Description of the Related Art In recent years, pollution of soil and water quality by volatile organic compounds (VOC) such as trichlorethylene has become a problem. Therefore, many attempts have been made at present regarding a method for purifying contaminated soil containing VOC.
As one method, in Japanese Patent Laid-Open No. 2001-25757, a contaminated soil is heated by using a rotary kiln, and
A method is described in which OC is thermally desorbed and the VOC is further burned and decomposed in an incinerator. However, since the contaminated soil containing VOC is very large, there is a problem that a heat source for heating the contaminated soil requires a large cost. When VOC contains chlorine, it is necessary to decompose by combustion at a considerably high temperature in order to avoid the generation of dioxins.
There is a problem that the cost of the heat source becomes larger. Further, although a large amount of detoxified soil is generated, there is also a problem that there is no method for using the detoxified soil in large amounts. On the other hand, the operating condition of the cement manufacturing factory changes according to the demand for cement. When the demand for cement is low, the operation of some of the firing equipment may be stopped, and the utilization of these is an issue.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and the equipment provided in a cement manufacturing plant such as a cement kiln is used for treating volatile organic compounds (VOC). Contaminated soil containing VOCs, which can open the way to effectively utilize, can heat the contaminated soil and burn VOCs at low cost, and can effectively utilize a large amount of treated detoxified soil. An object of the present invention is to provide a method for treating the above, a method for producing cement and an apparatus.

[0004]

In order to achieve the above object, a method for treating a contaminated soil containing a volatile organic compound (VOC) according to the present invention is a heat treatment apparatus for removing a volatile organic compound in a contaminated soil. After thermal desorption, the separated volatile organic compound is combusted and decomposed in a cement burning kiln. Since the temperature inside the cement burning kiln is high at about 1450 ° C., even VOCs containing chlorine can be safely decomposed without generating dioxin and the like. Also,
A rotary kiln or a rotary dryer is preferably used as the heat treatment device. in this way,
By using the idle kiln, a large amount of contaminated soil can be desorbed by heat, and by using the heat source of the cement burning kiln, VOC combustion decomposition can be performed at low cost. In the present specification, the term “volatile organic compound” or “VOC” is a concept including VVOC, VOC and SVOC (according to WHO classification) in the narrow sense below, unless otherwise specified. Highly volatile organic compound (VVOC) in a narrow sense: 1,1-dichloroethane, dichloromethane, trichloromethane (chloroform), etc., boiling point: 50 to 100 ° C. or lower. Volatile organic compound (VOC) in a narrow sense: tetrachloroethene (PCE), dibromochloromethane, tribromomethane, and the like, having a boiling point in the range of 50 to 100 ° C and 240 to 260 ° C. Narrowly defined semi-volatile organic compound (SVOC): dioctyl phthalate, dibutyl phthalate, tributyl phosphate and the like, having a boiling point of 240 to 260 ° C or higher and 380 to 400 ° C or lower.

In the present invention, it is preferable to use a rotary kiln or a rotary dryer from which the lining bricks have been removed. This facilitates the movement of waste, and has the advantage of reducing the energy consumption for rotating the rotary kiln. In the present invention, the rotary kiln is preferably a cement kiln, and the rotary dryer is preferably a rotary dryer for cement production. Further, in the present invention, as a heat source for thermally desorbing the volatile organic compounds in the contaminated soil,
It is preferable to utilize the waste heat of the cement firing kiln.
Thereby, a large amount of contaminated soil can be heated at low cost, and energy saving can be achieved. The heat treatment temperature is preferably set to a temperature higher than the boiling point of the target VOC, preferably 20 ° C. higher than the boiling point.

Then, it is preferable to use the soil from which the volatile organic compounds have been removed (detoxified soil) as a cement raw material. In particular, it is preferable to add the detoxified soil as a cement raw material to the cement burning kiln. As a result, the large amount of detoxified soil obtained can be effectively reused. In particular, since it is reused in the attached cement firing kiln, conventional equipment can be used as equipment for transporting a large amount of soil, and equipment investment and transportation cost can be kept low. Further, the detoxified soil can also be used as horticultural soil.

Further, the present invention is, as another form, a method for producing cement, in which the volatile organic compound-removed soil (detoxified soil) obtained by the above treatment method is used as a cement raw material. It is characterized in that it is put into a cement firing kiln as.

[0008] Furthermore, the present invention is, in another aspect, a heat treatment apparatus for contaminated soil containing a volatile organic compound, wherein the heat treatment apparatus heats and desorbs the volatile organic compound in the contaminated soil. It is characterized by using a kiln or a rotary dryer for cement production.
In the cement kiln or the rotary dryer for producing cement, it is preferable that the lining brick is removed.

The present invention can also be implemented as a cement manufacturing factory equipped with the above heat treatment apparatus.
In this case, it is preferable that the heat treatment device is provided in the vicinity of the cement burning kiln of the cement manufacturing facility in terms of piping and the like. As a result, V generated in the heat treatment device
It becomes easy to introduce the OC-containing exhaust gas or the detoxified soil into the cement burning kiln. The "raw material" in the production of cement in the present invention is a concept including what is used as a part of the raw material used in the production of cement.

[0010]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
Embodiments of a method for treating contaminated soil containing a volatile organic compound, a method for producing cement, and a heat treatment apparatus according to the present invention will be described. FIG. 1 shows an outline of an embodiment of a cement manufacturing plant for carrying out the method for treating contaminated soil containing a volatile organic compound and the method for manufacturing cement according to the present invention. In this cement manufacturing plant, a contaminated soil heat treatment equipment 200 is attached to the cement manufacturing equipment 100. The cement manufacturing facility 100 includes a cement firing kiln (rotary kiln) 102, a clinker cooler 103,
The calcining furnace 104 and the suspension preheater 106 are included as main equipment.

The cement burning kiln 102 is a burner 10.
8 is provided. The burner 108 includes a blower wind turbine (not shown) for supplying exhaust gas containing a volatile organic compound (VOC) described later, a supply pump 110 for supplying liquid fuel such as heavy oil, and an air blower (not shown) for supplying air. An air supply means such as a windmill is provided. The cement burning kiln 102 supports a cylindrical drum by a supporting roller (not shown) and can be rotated by a rotating means such as an electric motor (not shown). Further, the cement raw material (also referred to as a cement compound raw material) is installed so as to be inclined with a gentle gradient from the portion where the cement raw material is fed in toward the outlet of the cement clinker.
The cement raw material is cyclone 107 at the bottom of the preheater.
After being collected by the above, it is put into the cement firing kiln 102, lifted while rotating on the coating attached to the lining brick on the inner wall of the cement firing kiln 102, lowered, and repeated. Then, the cement raw material is fired by the radiant heat of the flame formed by the burner 108. Further, the cement burning kiln 102 is provided with a supply means for supplying a VOC-containing exhaust gas described later into the atmosphere. The introduction point of the VOC-containing exhaust gas is preferably the end of the cement burning kiln 102 on the side where the burner 108 is located. The VOC-containing exhaust gas is used as a combustion gas for burning the cement firing kiln 102, and the VOC in the exhaust gas is combusted and decomposed. Here, the VOC-containing exhaust gas is supplied by the burner 108.
Or directly in the atmosphere or both.

The clinker cooler 103 is a means for cooling the cement clinker discharged from the cement burning kiln 102. The clinker cooler 103 is divided into several chambers, and is cooled by the air supplied by the cooling wind turbine 112 installed in the lower air chamber of each chamber.

The calcining furnace 104 is a device for calcining the cement raw material, and includes a burner 114 for calcining the cement raw material. The burner 114 is a VO described later.
Blowing wind turbine (not shown) for supplying C-containing exhaust gas, supply pump 11 for supplying liquid fuel such as heavy oil
6 and air supply means such as an air blowing wind turbine (not shown). The calcination furnace 104 improves the decarboxylation rate by calcining the cement raw material and reduces the heat load of the cement calcination kiln 102 to ensure the calcination and to protect the cement calcination kiln 102 itself. Contribute. At the same time, the cement firing kiln 102
Effectively utilize the waste heat from the plant to improve the thermal efficiency of the entire cement manufacturing plant. Furthermore, cement burning kiln 102
Similarly, the VOC in the VOC-containing exhaust gas can be combusted and decomposed.

The suspension preheater 106 is a device for preheating the cement raw material, and is a cyclone 10
7 is stacked in multiple stages. In each cyclone 107, the gas component and the solid component are separated,
The cement raw material is preheated by suspending the cement raw material in the air flow in the duct and exchanging heat between the cement raw material and the gas.

On the other hand, the contaminated soil heat treatment equipment 200 is intended to effectively utilize contaminated soil containing a volatile organic compound (VOC) as a raw material for cement production.
It is equipment for thermally desorbing VOCs in the contaminated soil to render the contaminated soil harmless, and includes a heat treatment device 201 and its associated devices 202 to 208. The heat treatment apparatus 201 utilizes a rotary kiln (idle kiln) which is not in operation. This heat treatment device 201
Also, similarly to the cement burning kiln 102 described above, a cylindrical drum is supported by a supporting roller (not shown) and rotated by a rotating means (not shown).

Generally, in the rotary kiln used for cement production, the inner wall is protected by a brick lining in order to maintain the fire resistance during cement firing. However, in the heat treatment apparatus 201 according to this embodiment, this lining brick is removed. By removing this lining brick,
When the contaminated soil is put into the heat treatment apparatus 201 for treatment, the contaminated soil is easily moved and the energy consumption is significantly reduced. Further, it becomes easy to attach the stirring equipment and the partition plate. In the heat treatment device 201, the inner diameter of the cement kiln after removing the lining brick is 2 to 7 m, and 1.
It is suitable to install it with an inclination of 0 to 6.0%, preferably 1.2 to 1.6%.

The inlet of the heat treatment device 201 is separated from the existing suspension preheater. And
There, an inlet 202 for polluted soil containing a volatile organic compound (VOC) and an outlet 203 for an exhaust gas containing a volatile organic compound (VOC) are provided. A ventilation wind turbine 206 is provided as an exhaust means for the outlet 203 of the VOC-containing exhaust gas, whereby the heat treatment apparatus 2 is provided.
The VOC-containing exhaust gas in 01 can be extracted and sent to the cement manufacturing facility 100.

The outlet of the heat treatment apparatus 201 is separated from the existing clinker cooler to remove the detoxified soil 2
05 is provided. The detoxified soil extracted from the outlet 205 can be supplied to the cement manufacturing facility 100 via the belt conveyor 208. In addition, the exhaust heat inlet 2
No. 04 is provided, and the exhaust heat blowing port 204 is provided with an exhaust heat blowing wind turbine 207 as an air supply means, whereby air can be supplied.

The inlet and outlet of the heat treatment device 201 are
It may be the same as the existing state or the opposite. In addition, the above-mentioned inlet 202 of the heat treatment apparatus 201 is closed except when the contaminated soil is introduced, and the VOC gas outlet 203,
The air inlet 204 is also closed except when ventilation is performed, and the heat treatment apparatus 201 basically has a closed structure.

Next, the operation when the method for treating contaminated soil containing a volatile organic compound and the method for producing cement according to the present invention are carried out using the cement production plant having the above-mentioned structure will be described. In the present embodiment, the above-mentioned contaminated soil heat treatment facility 2 installed in the cement manufacturing plant is used.
At 00, the contaminated soil containing volatile organic compounds (VOC) is rendered harmless. The VOC-contaminated soil is introduced into the heat treatment apparatus 201 of the contaminated soil heat treatment equipment 200 through the input port 202. The target volatile organic compound is not particularly limited, but the volatile organic compounds and highly volatile organic compounds shown in Table 1 below are preferable.

[0021]

[Table 1]

Exhaust gas from the cement firing kiln 102 is previously blown into the heat treatment apparatus 201 through the exhaust heat blowing port 204, and the temperature inside the heat treatment apparatus 201 is equal to or higher than the boiling point of the VOC to be treated due to the exhaust heat of the exhaust gas. Is higher than the boiling point by 20 ° C. or more. As the extraction position of the exhaust gas, for example, the suspension preheater exhaust gas line 120, the exhaust gas introduction line 307 or the exhaust line 308 to the electrostatic precipitator (EP), the clinker cooler 1
The exhaust gas line from 03, etc. are mentioned. As described above, the heat treatment device 201 is installed with an inclination of 1.0 to 6.0%, and the rotation of the heat treatment device 201 easily moves the contaminated soil during the heat treatment. During the heat treatment, the heat treatment apparatus 201 preferably rotates at a speed of 0.5 to 3.0 rpm, for example, with the inner diameter of the lining brick removed from 4 to 5 m. Volatile organic compounds (VOC) in the contaminated soil are thermally desorbed in the heat treatment apparatus 201, separated from the contaminated soil and gasified. Then, as exhaust gas containing VOC, the outlet 203 is provided by the wind turbine 206 for ventilation.
And sent to the cement manufacturing facility 100.

In the cement manufacturing facility 100, the cement raw material is treated in parallel with the operation of the contaminated soil heat treatment facility 200. That is, the suspension preheater 10
Preheating of cement raw material at each cyclone 107 in 6,
Calcination is performed in the calcination furnace 104, and calcination is performed in the cement calcination kiln 102. Then, the VOC-containing exhaust gas introduced into the cement burning kiln 102 is fully exposed to a high temperature atmosphere and completely combusted and decomposed. At this time, since the cement firing kiln 102 is constantly kept at about 1450 ° C. in continuous operation, it is possible to prevent generation of dioxin due to combustion of VOC.

On the other hand, the outlet 205 of the heat treatment apparatus 201
The soil obtained is detoxified by removing VOC. The detoxified soil collected by the belt conveyor 208 is supplied to the cement manufacturing facility 100 as a raw material for cement manufacturing. The detoxified soil is added to the manufacturing process of the cement compound raw material as a part of the cement compound raw material. Further, the suspension preheater 106, the calcination furnace 104, and the cement firing kiln 102 can be charged into the charging site. Moreover, the boiling point of the volatile organic compound to be treated is less than 180 ° C., and the detoxified soil obtained when the heat treatment is performed at 200 ° C. or less does not destroy organic components necessary for horticultural soil, It can be used as a horticultural soil as it is or after an aggregate treatment by a conventional technique using a pan pelletizer or the like.

Other Embodiments Although the method for treating contaminated soil containing a volatile organic compound and the method for producing cement according to the present invention have been described with reference to the embodiment shown in FIG.
The present invention is not limited to such an embodiment, and modifications, changes and additions obvious to those skilled in the art are all included in the technical scope of the present invention.

In the above embodiment, the rotary kiln (cement kiln) was used as the heat treatment apparatus, but a rotary dryer for cement production can also be used in the same form as the heat treatment apparatus. This rotary dryer is used for drying raw materials in cement production. FIG. 2 shows a part of an embodiment of a cement manufacturing factory including a rotary dryer. Rotary dryer 300 is VO
Contaminated soil containing C is supplied from the supply line 302 to heat it. The heating is performed by the exhaust heat of the exhaust gas from the cement firing kiln 102 or the like supplied from the supply line 304. The exhaust gas from the rotary dryer 300 is
The dust is removed by the electric dust collector 306 and the cement firing kiln 10
Sent to 2. The heated detoxified soil is pulverized by the raw material pulverizer 310, and after the particles having a predetermined particle size are separated by the separator 312, the subsequent steps of homogenization, preheating, calcination and firing through a line 314. Sent to. Like the cement kiln (rotary kiln), such a rotary dryer 300 can also be used if it is idle. In addition, these may be used in combination, if necessary.

[0027]

As is apparent from the above, according to the present invention, the equipment provided in a cement manufacturing plant such as a cement kiln can be effectively utilized for the treatment of volatile organic compounds (VOC). Of the polluted soil containing volatile organic compounds, which can open the soil, can heat the polluted soil and burn VOCs at low cost, and can effectively utilize a large amount of the treated detoxified soil. A treatment method, a cement manufacturing method and an apparatus are provided.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating an embodiment of a cement manufacturing plant for carrying out a heat treatment method and a cement manufacturing method according to the present invention.

FIG. 2 is a conceptual diagram for explaining a part of a cement manufacturing factory for explaining a rotary dryer for cement manufacturing.

[Explanation of symbols]

100 cement production equipment 102 Cement firing kiln (rotary kiln) 103 Clinker Cooler 104 Calciner 106 Suspension preheater 107 cyclone 108, 114 burners 110 supply pump 112 Cooling windmill 116 Supply pump 200 Contaminated soil heat treatment equipment 201 heat treatment equipment 202 Contaminated soil inlet containing VOC 203 VOC-containing exhaust gas outlet 204 Exhaust heat inlet 205 Detoxification of detoxified soil 206 Windmill for ventilation 207 Exhaust heat blown wind turbine 208 belt conveyor 300 rotary dryer 306 Electric dust collector 310 Raw material crusher 312 separator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Saito             3-8-1, Nishikanda, Chiyoda-ku, Tokyo Pacific Ocean             Inside Cement Co., Ltd. (72) Inventor Utama Tamashige             3-8-1, Nishikanda, Chiyoda-ku, Tokyo Pacific Ocean             Inside Cement Co., Ltd. F-term (reference) 4D004 AA41 AB05 AB06 BA02 CA12                       CA22 CA27 CA28 CB09 CB31                       CB34 CB36

Claims (10)

[Claims] 1. A volatile organic compound characterized in that the volatile organic compound in contaminated soil is thermally desorbed by a heat treatment apparatus, and then the separated volatile organic compound is burned and decomposed in a cement burning kiln. How to treat contaminated soil. 2. The method for treating contaminated soil containing a volatile organic compound according to claim 1, wherein the heat treatment device is a rotary kiln or a rotary dryer. 3. The method for treating contaminated soil containing a volatile organic compound according to claim 2, wherein a rotary kiln or a rotary dryer from which an inner brick is removed is used. 4. The volatilization according to claim 1, wherein exhaust heat of the cement burning kiln is used as a heat source for thermally desorbing volatile organic compounds in the contaminated soil. Method for treating contaminated soil containing organic compounds. 5. The method for treating contaminated soil containing a volatile organic compound according to claim 1, wherein the soil from which the volatile organic compound has been removed is used as a cement raw material. 6. The soil from which the volatile organic compounds have been removed is used as horticultural soil.
5. A method for treating contaminated soil containing the volatile organic compound according to any one of 4 above. 7. A method for producing cement, characterized in that the volatile organic compound-removed soil obtained by the treatment method according to any one of claims 1 to 4 is put into a cement firing kiln as a cement raw material. . 8. A heat treatment apparatus for a contaminated soil containing a volatile organic compound, which comprises using a cement kiln or a rotary dryer for cement production to thermally desorb the volatile organic compound in the contaminated soil. 9. The heat treatment apparatus for contaminated soil containing a volatile organic compound according to claim 8, wherein the cement kiln or the rotary dryer for producing cement has lining bricks removed. 10. A cement manufacturing plant, wherein the heat treatment device according to claim 8 or 9 is attached in the vicinity of a cement firing kiln.