JPH085257A - Exhaust gas treatment method for sintering machine - Google Patents

Abstract

(57) Abstract: without using Objective scrubber, to provide a technique for effectively capturing collection also of the order of 0.3μm fine dust. [Structure] Coarse dust contained in the exhaust gas from the front wind box group 11 is electrified by the electrostatic precipitator 14, the charged coarse dust is sent to the cyclone 24, and a large amount of fine dust from the rear wind box group 21 is separately added. This is a treatment method in which exhaust gas containing the same is sent to the cyclone 24, and the fine dust is aggregated in the coarse dust in the cyclone 24. Since fine dust of about 0.3 μm can be removed very easily without using a scrubber or a bag filter, equipment costs and operating costs for exhaust gas treatment can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment technology for a sintering machine.

[0002]

2. Description of the Related Art It is well known that iron ore, coke, lime and other auxiliary materials are charged into a blast furnace (blast furnace) to produce pig iron in the blast furnace. For example, from the viewpoint of reaction in the blast furnace, yield as a raw material, etc., the iron ore is not preferable to have a small diameter or powder. Therefore, a sintering machine for increasing the diameter of these small-diameter or powdered iron ores is required. Since the iron ore is heated to the sintering reaction temperature in the sintering machine, the exhaust gas cannot be released to the atmosphere as it is because the sulfur (S) and other components contained in the iron ore are gasified. Therefore, it becomes necessary to treat the exhaust gas of the sintering machine.

FIG. 2 is a layout view of an exhaust gas treatment equipment of a conventional sintering machine. The exhaust gas treatment equipment of the sintering machine 100 electrically discharges the exhaust gas through a wind box group 101, a communicating pipe 102 and a collecting pipe 103. The dust is removed to the dust collector 104, the dust is removed by the electric dust collector 104, and the exhaust gas after that is sent to the desulfurization device 106 through the blower 105, where SO ₂ is removed, and the exhaust gas after that is discharged from the chimney 107 to the atmosphere. is there.
Since this type of exhaust gas treatment equipment treats the entire amount of exhaust gas, the equipment becomes bulky and the electrostatic precipitator 104
Due to its ability to remove fine dust of about 0.3 μm,
There is a disadvantage that colored exhaust gas from the chimney is often emitted. This is because fine dust of 0.3 μm becomes colored due to a light confusion phenomenon.

Therefore, as a more improved exhaust gas treatment technique, for example, Japanese Patent Application Laid-Open No. 54-107804 "Exhaust gas processing method in DL type sintering machine" and Japanese Patent Application Laid-Open No. 52-351.
No. 64 “Method and apparatus for removing harmful substances from waste gas of sintering apparatus” has been proposed. The above is the main exhaust gas of the sintering machine, which uses the relatively low temperature gas from the former stage (feeding side) as air for cooling the product, and then uses it again as the supply air to the latter stage of the sintering machine (exhaust side). This is the technology to be offered.
As a result of effective use of heat, the total amount of exhaust gas is reduced and the burden of exhaust gas treatment can be reduced.

Among the main exhaust gas of the sintering machine, the above is to remove the exhaust gas in the preceding stage only by the electrostatic precipitator and remove the exhaust gas in the subsequent stage by the electrostatic precipitator and the scrubber. Fine dust of 0.3 μm is generated by the scrubber. It can be collected and the treatment cost can be reduced compared to the case where all the exhaust gas is treated by a scrubber.

[0006]

However, in order to achieve so-called energy saving, the above requires a heat exchanger and a cooler, which complicates the equipment. Although the amount of exhaust gas is reduced, the treatment of exhaust gas is not easy because the treatment of exhaust gas is not particularly considered. In addition, since the above scrubber removes dust, maintenance of the scrubber is not easy and operating costs increase.

Therefore, an object of the present invention is to provide a technique capable of effectively collecting even fine dust of about 0.3 μm without using a scrubber.

[0008]

Means and Actions for Solving the Problems In order to achieve the above object, the present invention provides a wind box group attached to a sintering machine for adjusting a small diameter or powder iron ore to a desired size. The exhaust gas is treated in the next step in a sintering machine which is divided into a pre-stage wind box group and a post-stage wind box group along the flow direction of 1. First step: The exhaust gas is extracted from the front wind box group and sent to the electrostatic precipitator, and the exhaust gas is extracted from the rear wind box group and sent to the cyclone. Second step: The electric dust collector separates dust from the exhaust gas from the pre-wind box group and sends the charged dust to the cyclone, while sending the exhaust gas to the exhaust gas treatment device. Third step: the cyclone is mixed with the charged dust and the exhaust gas from the rear wind box group, and then centrifuged.
The dust is extracted, while the exhaust gas is sent to the exhaust gas treatment device. Fourth step: The exhaust gas treatment device collectively processes the exhaust gas from the electrostatic precipitator and the exhaust gas from the cyclone, and discharges them to the outside through the chimney.

Further, it is preferable to add the following steps. The dust extracted from the cyclone in the third step is treated with another electrostatic precipitator, and the generated dust is further wet treated to be a sintering raw material.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a layout view of an exhaust gas treatment facility of a sintering machine according to the present invention. First, the sintering machine 1 ignites a raw material supply machine 2 for dropping a raw iron ore at an inlet 1a and a raw iron ore. Ignition device 3 and a conveyor 4 that horizontally conveys the supplied iron ore
And a drive pulley 5 and a driven pulley 6 for driving and guiding the conveyor 4. The raw iron ore dropped from the raw material feeder 2 is raised to the sintering temperature during the movement from the inlet side to the outlet side at a predetermined speed as indicated by the arrow to be sintered, that is, to be bonded and increased in diameter, and exit 1b. At, the desired sintered iron ore is cut out. Exhaust gas containing a large amount of dust of 10 μm or more (referred to as “coarse dust”) was generated in the first half 1F of the sintering machine 1 because the temperature of the raw iron ore was gradually raised.
Further, in the latter half 1R, exhaust gas containing a large amount of dust of about 0.3 μm (referred to as “fine dust”) and a large amount of SO ₂ is generated.

Next, the exhaust gas treatment facility 10 will be described.
The exhaust gas treatment facility 10 is arranged below the conveyor 4 and is provided with a front air box group 11 for sucking the exhaust gas generated in the first half 1F.
A communication pipe 12 and a front collection pipe 13 for guiding the exhaust gas of the front wind box group 11, and a first pipe connected to the front collection pipe 13.
An electric dust collector 14, a collecting pipe 15, a blower 16, a desulfurization device 17 as an exhaust gas treatment device, and a chimney 18, which are sequentially arranged from a gas outlet 14a of the first electric dust collector 14, and a rear half 1R arranged below the conveyor 4. Of the rear wind box group 21 for sucking the generated exhaust gas, a communication pipe 22 and a rear collecting pipe 23 for guiding the exhaust gas of the rear wind box group 21, and a cyclone 24 connected to the rear collecting pipe 23, A connecting pipe 25 connecting the gas outlet 24a of the cyclone 24 to the collecting pipe 15, and the dust outlet 1 of the first electrostatic precipitator 14.
A first dust extraction pipe 26 connecting 4b to the inlet side of the cyclone 24, and a dust outlet 24b of the cyclone 24.
And a second dust extraction pipe 27 for taking out dust from the. The first dust extraction pipe 26 is a lining pipe whose inner surface is coated with an insulating material such as resin or ceramic.

Further, in the present embodiment, the third dust extraction pipe 31 is branched from the second dust extraction pipe 27, and the third dust extraction pipe 31 is provided with the second electrostatic precipitator 32 and the wet treatment device 3.
It is characterized in that it is extended to the raw material feeder 2 through 3. The first and second electrostatic precipitators 14 and 32 are dry separators, and are separators of a type that charges a dust in a gas by applying a strong electrostatic field to exhaust gas and separates the dust in an electric field. The equipment cost is the most expensive among the separators. Further, the cyclone 24 introduces the exhaust gas into the conical chamber in a tangential direction to rotate the same, and separates the heavy gas to the outside by the centrifugal force with the light gas as the swirling center. The equipment cost is low and the pressure loss is small. . However, the limit of the dust that can be separated is 5 μm. The cyclone is preferably a multi cyclone composed of a plurality of cyclones.

Although not shown in FIG. 1, a double valve is provided in the first dust extraction pipe 26 to prevent blow-through, and each upstream of the confluence of the collecting pipe 15 and the connecting pipe 25. A pressure adjusting damper is provided on each of the collecting pipe 15 and the connecting pipe 25 on the side to balance the pressure. In addition, a check valve, a damper, and an on / off valve will be installed in the pipeline if necessary.

The operation of the exhaust gas treatment equipment of the sintering machine having the above construction will be described step by step. First step: In FIG. 1, the exhaust gas is extracted from the front air box group 11, the exhaust gas is sent to the first electric dust collector 14, and the exhaust gas is extracted from the rear air box group 21, and the exhaust gas is sent to the cyclone 24.

Second step: The first electrostatic precipitator 14 separates dust from the exhaust gas from the pre-stage wind box group 11 and sends charged dust to the cyclone 24, while
The exhaust gas is directed to the desulfurization device 17. Specifically, sintering machine 1
The exhaust gas generated in the first half 1F contains a relatively large amount of coarse dust of 10 μm or more, and fine dust is added to this. Therefore, such exhaust gas is discharged from the first electrostatic precipitator 1
When the treatment is carried out in 4, the electric dust collector generally performs the treatment in a laminar flow state, so that the fine dust is less likely to be aggregated in the coarse dust, and the charge chamber (previous charging chamber) in the vicinity of the exhaust gas introduction side of the electric dust collector 14 is coarse. Dust easily settles by gravity and is easily collected in a charged state. Therefore, the charged coarse dust collected in the pre-charge chamber of the first electrostatic precipitator 14 can be sent to the cyclone 24 through the first dust extraction pipe 26. Since the first dust extraction pipe 26 is an insulating material lining pipe, it maintains a good charged state of coarse dust.

Third step: At the inlet of the cyclone 24,
The charged dust and the exhaust gas from the rear wind box group 21 are mixed. Since the exhaust gas from the rear wind box group 21 contains a large amount of fine dust of about 0.3 μm, by mixing this with the charged dust (coarse dust), the fine dust aggregates with the charged coarse dust. That is, in the cyclone 24, the swirling flow is a turbulent flow, so that the dust particles frequently come into contact with each other, and since the coarse dust particles are charged, suction and agglomeration are active. As a result, the dust after coagulation becomes at least 10 μm and is sufficiently separated by the cyclone. Meanwhile, the exhaust gas is removed fine dust things S0 ₂ containing is sent to the desulfurizer 17 through a collecting pipe 15.

Fourth step: In the desulfurization device 17, the exhaust gas from the first electrostatic precipitator 14 and the exhaust gas from the cyclone 24 are collectively subjected to a process such as desulfurization, and discharged through the chimney 18 to the outside.

Attaching step: The dust extracted from the cyclone 24 in the third step is treated by the second electrostatic precipitator 32, and the generated dust is further treated by the wet treatment device 33 to be used as a sintering raw material. In addition, in FIG. 1, the attached process is performed in series with the third dust extraction pipe 31, but this process does not necessarily need to be continuously processed with the pipe 31, and, for example, the dust extracted from the second electrostatic precipitator 32 is Batch processing may be carried out in which the sintering raw material is conveyed to the raw material feeder 2 by a conveyor, a truck, or the like, and the sintering raw material after the treatment is carried there.

Next, the results of comparative experiments between the method of the present invention and the conventional method will be described. The "Invention Example" and "Comparative Example 1" were tested with the sintering machine 1 and the exhaust gas treatment facility 10 shown in FIG.
"Comparative Example 2" was tested on the sintering machine 100 of. “Comparative Example 1” corresponds to the equipment of FIG. 1 in which the insulating material of the first dust extraction pipe 26 is removed. Total exhaust gas amount 1.2 × 1
0 ⁶ m ³ / Hr, the charging chamber is the first with an electrostatic precipitator with 4 chambers
The experiment was carried out by setting the chamber to 50 kV continuous charge, the total number of wind box groups was 28, and in the present invention example, boxes 1 to 16 were front wind box groups and boxes 17 to 28 were rear wind box groups. Evaluation is chimney 1
A measurement hole was opened at an intermediate position in the height direction of 8,107, and a "type 1 dust sampler" was inserted into this hole to quantitatively measure the amount of fine dust collected on the filter paper, and the chimney 18,1
It was decided to visually judge the degree of coloring of the exhaust gas emitted from 07.

[0020]

[Table 1]

As shown in Table 1, the "Comparative Example 2" tested by the conventional equipment shown in FIG. 2 has a fine dust amount of 15 mg / m ³ N.
Since the exhaust gas was colored, the evaluation was x. Note that m ³ N means a standard cubic meter, and is also described as Nm ³ . On the other hand, in the “invention example” tested by the equipment of FIG. 1, the amount of fine dust was significantly reduced to 5 mg / m ³ N,
Moreover, since the exhaust gas was colorless, the evaluation was ◯. In addition, in "Comparative Example 1" in which the connection pipe 25 was replaced with a non-insulated pipe from the equipment of FIG. 1, the amount of fine dust was as high as 12 mg / m ³ N, and the exhaust gas was colored. Therefore, the evaluation was x. Therefore, it has been found that there is a special action and effect in that the coarse dust is charged into the cyclone 24 while being charged and the fine dust is aggregated in the charged dust.

A desulfurization device is suitable for the exhaust gas treatment device 17, but a denitrification device may be added to the desulfurization device, which means that the exhaust gas treatment device 17 is a whole of treatment devices according to exhaust gas emission standards. Further, in FIG. 1, the boundary between the pre-stage air box group 11 and the post-stage air box group 21 is set to the substantially center of the sintering machine 1, but this position may be changed before or after.

[0023]

The present invention has the following effects due to the above configuration. According to claim 1, the coarse dust contained in the exhaust gas from the pre-wind box group is charged by an electrostatic precipitator, the charged coarse dust is sent to a cyclone, and the exhaust gas containing a large amount of fine dust from the post-wind box group separately. To the cyclone,
The fine dust is agglomerated with the coarse dust in the cyclone, and the fine dust of about 0.3 μm can be easily removed from the exhaust gas. That is, according to the first aspect, the fine dust can be removed very easily without using a scrubber or a bag filter, so that the facility cost and the operating cost related to the exhaust gas treatment can be reduced.

Since the dust from the cyclone is used as a sintering raw material, the yield of the raw material can be improved.

[Brief description of drawings]

FIG. 1 is a layout view of an exhaust gas treatment facility of a sintering machine according to the present invention.

[Fig. 2] Layout of exhaust gas treatment equipment for conventional sintering machines

[Explanation of symbols]

1 ... Sintering machine, 2 ... Raw material feeder, 10 ... Exhaust gas treatment facility,
11 ... Front air box group, 14 ... Electrostatic precipitator (first electric precipitator), 17 ... Exhaust gas treatment device (desulfurization device), 18 ... Chimney, 21 ... Rear air box group, 24 ... Cyclone, 32 ... Another electric precipitator ( Second electrostatic precipitator), 33 ... Wet processing apparatus.

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[Procedure amendment]

[Submission date] June 30, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

An object of the present invention is without using scrubber is to provide a technique capable <br/> current effectively capturing also 0.3μm about fine dust.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Next, the exhaust gas treatment facility 10 will be described.
The exhaust gas treatment facility 10 is arranged below the conveyor 4 and is provided with a front air box group 11 for sucking the exhaust gas generated in the first half 1F.
When, a communicating pipe 12 and the front catching Atsumarikan 13 guides the exhaust gas of the preceding stage wind box group 11, the coupling to the front catching Atsumarikan 13 1
The electric dust collector 14, the collecting pipe 15, the blower 16, the desulfurization device 17 and the chimney 18 as exhaust gas treatment devices, which are sequentially arranged from the gas outlet 14a of the first electric dust collector 14, and the latter half 1R disposed below the conveyor 4. and subsequent wind box group 21 for sucking generation exhaust gas, the communicating pipe 22 and the rear catching Atsumarikan 23 for guiding the exhaust gas of the subsequent wind box group 21, a cyclone 24 connected to the rear catching Atsumarikan 23, this A connecting pipe 25 connecting the gas outlet 24a of the cyclone 24 to the collecting pipe 15, and the dust outlet 1 of the first electrostatic precipitator 14.
A first dust extraction pipe 26 connecting 4b to the inlet side of the cyclone 24, and a dust outlet 24b of the cyclone 24.
And a second dust extraction pipe 27 for taking out dust from the. The first dust extraction pipe 26 is a lining pipe whose inner surface is coated with an insulating material such as resin or ceramic.

Claims (2)

[Claims] 1. A wind box group attached to a sintering machine for adjusting a small-diameter or powdered iron ore to a desired size is divided into a front wind box group and a rear wind box group along the iron ore flow direction. An exhaust gas treatment method for a sintering machine, which comprises treating the exhaust gas in the following steps in separate sintering machines. First step: The exhaust gas is extracted from the front wind box group and sent to the electrostatic precipitator, and the exhaust gas is extracted from the rear wind box group and sent to the cyclone. Second step: The electric dust collector separates dust from the exhaust gas from the pre-wind box group and sends the charged dust to the cyclone, while sending the exhaust gas to the exhaust gas treatment device. Third step: the cyclone is mixed with the charged dust and the exhaust gas from the rear wind box group, and then centrifuged.
The dust is extracted, while the exhaust gas is sent to the exhaust gas treatment device. Fourth step: The exhaust gas treatment device collectively processes the exhaust gas from the electrostatic precipitator and the exhaust gas from the cyclone, and discharges them to the outside through the chimney. 2. The sintering raw material according to claim 1, wherein the dust extracted from the cyclone in the third step is treated by another electrostatic precipitator, and the generated dust is further wet treated to be a sintering raw material. Exhaust gas treatment method for sintering machine.