JPS62227418A - Dust collecting method for molten iron pretreatment plant - Google Patents

Abstract

PURPOSE:To easily regenerate filter cloth collecting dust of dust-containing gas coming out of a molten iron pretreatment plant by adhering to the filter cloth a precoating agent to protect filter cloth from getting deliquenscence of collecting dust. CONSTITUTION:Dust-containing gas generated from a molten iron predetermined plant is guided into a guide duct 5. At that time, a precoating agent such as purple oxide or the like to protect filter cloths 3 of the primary dampers 6a-6d from getting deliquenscence of collecting dust is adhered beforehand to form a protecting layer. In guiding the precoating agent in, high-temperature clean air is guided out of a blower 14 through a guide duct 13 to form the precoating agent supplied from a storage tank 17 on the filter cloth 3. Therefore, provided dust containing calcium chloride is introduced in, sticky collected dust can be protected from adhering to the filter cloth, and heat of dust-containing gas is utilized effectively to prevent deliquenscence.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention is a method for filtering dust-containing gas generated from hot metal pretreatment equipment at a steel mill, etc., using a dust collector such as a bag filter using a filter cloth. This invention relates to a dust collection method for dust collection processing.

(Prior art) Generally, for the purpose of improving steelmaking technology and producing high-quality steel, a torpedo car that receives pig iron from a blast furnace is moved to a hot metal pretreatment facility, where it is passed through a lance to the torpedo car along with nitrogen gas and various Raw materials (calcium oxide, calcium chloride, calcium fluoride, powdered sintered ore, etc.) are injected to perform preliminary treatments such as desiliconization, dephosphorization, and desulfurization of hot metal. Since a large amount of high-temperature dust-containing gas is generated during such pretreatment of hot metal, it is necessary to introduce it into a dust collector through a smoke hood and collect the dust to purify the working environment.

(Issues to be Solved by the Invention) However, some of the auxiliary raw materials are scattered and mixed into the dust-containing gas generated from the hot metal pretreatment equipment during each of the above-mentioned pretreatments. In particular, calcium chloride, an auxiliary raw material used in the dephosphorization process, is extremely deliquescent, and if the content of calcium chloride in the dust-containing gas is high, it absorbs moisture from the surrounding area and becomes sticky. occurs violently. For this reason, in dust collectors such as bag filters that use filter cloth, a deliquescence phenomenon occurs on the filter cloth surface of the bag or inside the machine, and the filter cloth becomes sticky and sticky, resulting in severe accumulation of dust and clogging. It has been impossible to collect dust using a bag filter because it makes it impossible to regenerate the filter cloth, and it also makes it impossible to smoothly discharge and transport the dust from the lower hopper.

Therefore, the present invention was developed in view of the above circumstances, and can prevent problems such as moisture absorption and clogging of the filter cloth caused by deliquescence on the filter cloth surface, and can easily regenerate the filter cloth by brushing off the collected dust. It is an object of the present invention to provide a dust collection method that allows dust-containing gas from a hot metal pretreatment facility to be efficiently filtered and collected using a bag filter without any support.

[Structure of the invention]

(Means and effects for solving the problem) In order to achieve the above object, the dust collection method of the present invention uses calcium chloride in the collected dust when introducing dust-containing gas generated from hot metal pretreatment equipment. A pre-coat agent such as iron oxide powder to protect the filter cloth from deliquescence is introduced in advance and adhered to the surface of the filter cloth to form a protective layer, and then dust-containing gas from the hot metal pretreatment equipment is introduced. The protective layer on the surface of the filter cloth is used to collect dust by filtration.

(Example) An embodiment of this invention will be described below.

First, for convenience of explanation, the configuration of the dust collector, which is a bag filter used in this invention, will be explained with reference to FIG. Art room 2a.

Inside 2b, 2c, and 2d, a large number of cylindrical bugs 3 are arranged in parallel in a hanging state.

In addition, a hopper 4 is provided at the bottom of each compartment 2a to 2d.
a, 4b, 4c, and 4d are provided, and high-temperature dust-containing gas generated from hot metal pretreatment equipment (not shown) is sucked and conducted to these lower hoppers 4a to 4d via a collection hood, etc. The gas introduction ducts 5 each have a secondary damper 5a, 5
b, 6c, and B'd. On the other hand, an exhaust duct 7 is connected to the upper part of each compartment 2a to 2d, and the terminal side of the exhaust duct 7 is connected to a suction blower 8 to exhaust the secondary side J run air to the outdoors or the like. In addition, a backwashing type dust collecting mechanism 9 is provided at the top, and this is used to remove the collected dust from the compartments 2 on both sides.
Circulation dampers 10a and 10d on a and 2d
The backwashing duct 11 of the brushing-off mechanism 9 is connected to the secondary dampers 12a and 1, respectively.
2 b, 12 c.

It is connected to the upper part of each compartment 2a to 2d via 12d.

Further, a secondary side high temperature clean air outlet duct 13 is connected to each of the compartments 2a to 2d, and a precoat agent supply duct 15 is connected to this via a blower 14. A precoat agent storage tank 17 is connected via the body cutting device 16, and its supply duct 15 is connected to each of the lower hoppers 4a to 4a.
4d respectively pre-coated dampers 18a, 18b, 18c
.

18d. In addition, each lower hopper 4
A to 4d have a discharge valve or the like at the lower end for discharging the dust to the outside of the machine.

To describe a method for filtering and collecting dust-containing gas generated from hot metal pre-treatment equipment using the bag filter having the above-mentioned configuration, first, iron oxide powder is introduced into the storage tank 17 as a pre-coating agent. Leave it there. This iron oxide powder is the easiest and most stable supply within the steelworks, and is collected and recovered through steelmaking converter ventilation dust collection, blast furnace cast bed dust collection, etc.

When starting up the dust collection equipment, first open each secondary damper 6a to 6d of the introduction duct 5, and then open the secondary damper 12a.
~12d is closed, the circulation damper 10a,
10d and open the precoat dampers 18a to 18d. In this state, the suction blower 8 is operated to introduce outside air from the end hood side (not shown) of the introduction duct 5 by this suction. In parallel with this, the blower 14 is operated,
Air from the secondary clean side of the machine is led out from the outlet duct 13 and sent to the supply duct 15, and on the way there, the powder cutting device 16 mixes iron oxide powder, which is a pre-coating agent, in the storage tank 17. The iron oxide powder is introduced into each of the lower hoppers 4a to 4d by air conveyance. The precoat agent thus introduced into each of the lower hoppers 4a to 4d is mixed and conveyed with the outside air from the introduction duct 5 to form a protective layer on the filter cloth surface of each bag 3 in each of the compartments 2a to 2d.

In this way, when a protective layer is sufficiently formed on the filter cloth surface of each bag 3, the system enters the state of sucking and collecting the high temperature dust-containing gas from the hot metal pretreatment equipment. In other words, each pre-coat damper 13a~
18d is closed and the powder cutting device 16 and blower 1 are closed.
Stop 4. Further, the secondary dampers 6a to 6d are opened, and the secondary dampers 12a to 12d and the circulation dampers 10a and 10d are closed. In this state, high-temperature dust-containing gas generated from the hot metal pretreatment equipment is introduced from the duct 5 to each lower hopper 4a through the suction blower 8.
4d into each of the compartments 2a to 2d. In this way, the dust-containing gas containing calcium chloride is filtered and collected on the surface of the protective layer formed on the filter cloth surface of each bag 3. The air purified by the filtration and dust collection is suctioned from the upper part through the exhaust duct 7 to the suction blower 8 and discharged outdoors as secondary clean air.

Furthermore, when it is notified that the dust dust removal time has come by a signal from the timer or the pressure loss resistance detector of the bug 3 during the above-mentioned dust collection operation, the backwash type collecting dust removal mechanism 9
Thus, each of the compartments 2a to 2d is sequentially switched to the backwash mode one by one, and the dust collected from the bugs 3 is backwashed off.

For example, when backwashing is performed from the first compartment 2a, the other compartments 2b to 2d are left in the same dust collection operation as described above, and the dust collection operation is continued as shown in FIG. By closing the primary damper 6a of the first compartment, opening the circulation damper 10d, and intermittently opening the secondary damper 12a multiple times, the compartment 2a is closed.
The collected dust is brushed off by repeatedly contracting and expanding each bag 3 inside. As the air source for this backwashing, high-temperature clean air from the secondary side of the machine taken out from the circulation damper 10d to the backwashing duct 11 is used. This backwashing air blows off the dust collected on the filter cloth of the bag 3 together with the protective layer, and discharges it out of the machine from the lower hopper 4a.

In this way, the first compartment 2a, in which the bug 3 has been regenerated by blowing off the collected dust, introduces the dust-containing gas again to perform filtration and dust collection. The method at this time is to use the circulation damper 1 together with the secondary damper 12a after the above-mentioned backwashing is completed.
0d is closed, the pre-coat damper 18a is opened, and in this state, the blower 14 is operated to take out the high temperature clean air on the secondary side inside the machine to the outlet duct 13 and send it to the supply duct 15. 16 supplies iron oxide powder, which is a pre-coating agent, to the compartment 2.
At the same time, the primary damper 6a is opened to suck and introduce the high-temperature dust-containing gas into the lower hopper 4a from the introduction duct 5, and the high-temperature dust-containing gas and iron oxide powder are conveyed into the lower hopper 4a. is supplied into the compartment 2a for about 1 to 2 minutes in a wrapped state with secondary clean air mixed with iron oxide. Create a protective layer on the filter cloth surface of Bug 3. After this, the cutting device 16 and the blower 14 are stopped, the precoat damper 18a is closed, and the high-temperature dust-containing gas is continuously sucked and introduced to resume filtration and dust collection.

Thereafter, backwash filter cloth regeneration and protective layer generation in the second, third, and fourth compartments 2b to 2d, and dust-containing gas filtration and dust collection restart are repeated in the same manner one after another.

The above protective layer was formed by a mixed dilution method in which the dust-containing gas was wrapped and introduced together with clean air mixed with a pre-coat agent, but the above-mentioned method was performed without introducing the dust-containing gas with the damper closed. It is also possible to carry out the process by introducing only clean air mixed with a pre-coating agent.

Incidentally, the dust-containing gas generated from the hot metal pretreatment equipment contains highly deliquescent calcium chloride, which is an auxiliary raw material, in the dephosphorization process of the hot metal pretreatment, as described above. This dust containing calcium chloride deliquesces over time. That is, it absorbs moisture from its surroundings, increasing its weight and becoming sticky. In particular, the higher the content of calcium chloride, the more severe the deliquescence phenomenon is, and the temperature also has a considerable effect on the deliquescence, which is more likely to occur as the temperature drops from high temperature to room temperature. However, the content of calcium chloride in the dust-containing gas generated from the hot metal preliminary equipment is usually quite high, about 10 to 30% per dust content of 2 g/N77Z3.

The gas generation temperature at this time is several hundred degrees, which is very high and does not immediately cause deliquescence, but when it comes to the dust collector body 1, it ranges from 130 degrees Celsius to room temperature, and the processing time of the dust gas is - This process takes approximately 20 to 80 minutes, and depending on the production plan, this process may be continuous, or may be performed after a certain period of time, and may also be stopped for a long time during periodic inspections of the dust collector. Therefore, if the dust is filtered and collected in the bag 3 without forming the above-mentioned protective layer, the collected dust will cause a deliquescent phenomenon and stick to the filter cloth of the bag 3, resulting in severe clogging of the filter cloth and Not only is it difficult to shake off the collected dust, making it impossible to regenerate the filter cloth, but it is also difficult to discharge the collected dust outside the machine, making it impossible to collect dust using a bag filter.

Therefore, as mentioned above, a protective layer of iron oxide powder is always formed on the filter cloth surface of the bag 3 before introducing the dust-containing gas, and then the dust-containing gas is introduced and filtered and collected. The iron oxide powder in the protective layer absorbs moisture generated by the deliquescence of calcium chloride in the dust, preventing it from coming into direct contact with the filter cloth. This prevents the collected dust from sticking to the filter cloth in a sticky state, reduces clogging of the filter cloth, and allows the collected dust to be easily blown off by introducing backwash air. , filter cloth can be regenerated. Furthermore, the dust that has been brushed off can be smoothly discharged and transported from the lower hopper to the outside of the machine.

Furthermore, since the above-mentioned deliquescence phenomenon is likely to occur due to a drop in temperature, keeping the inside of the machine as warm as possible is effective in preventing deliquescence. However, in the method described above, the heat of the dust-containing gas introduced at high temperature is used for the forward motion to keep the inside of the machine warm, which is also effective in preventing deliquescence.

In other words, when introducing the precoat agent, without using outside air,
The secondary side high temperature clean air inside the machine is led out by the blower 14 through the outlet duct 13, and the high temperature clean air is loaded with the deliquescent inhibitor supplied from the storage tank 17 and sent back into the machine, and then the filter cloth surface of each bag 3 is delivered. By forming a protective layer on the air, cold air from the outside does not enter the cabin, keeping each bug and the inside of the cabin warm. Also, when the collected dust is brushed off by backwashing air, the dust removal mechanism 9 is used to measure the secondary height inside the machine.
Since iA clean air is extracted and inserted as backwash air, dust can be removed without cooling the bugs or the inside of the machine while keeping it warm, which helps prevent deliquescence.

Next, another embodiment of the present invention will be described with reference to FIGS. 3 and 4. Here, unlike the suction type dust collector of the above embodiment, a push type dust collector is used. Components having the same configuration as those in the above embodiment are given the same reference numerals to simplify the explanation. However, in the case of this embodiment, the dust-containing gas from the hot metal pretreatment equipment is transferred to the inlet duct 5 by the suction blower 8.
It is fed into each of the lower hoppers 4a to 4d through the hoppers 4a to 4d, and from there, it is introduced into the bag 3 in each of the compartments 2a to 2d, where it is filtered and collected on the protective layer of the filter cloth surface of the bag 3. The dust collected on the filter cloth of each bag 3 is sequentially backwashed into the lower hoppers 4a to 4d and discharged from each compartment 2a to 2d. The backwashing is done in each lower hopper 4a~
4d is provided with a suction duct 20 connected via secondary dampers 12a to 12d, and the end of this suction duct is connected to the upstream side of the suction blower 8 of the dust-containing gas introduction duct 5, and for example, the first When it is time to dust off the collected dust in the compartment 2a, the secondary damper 12a and the primary damper 6a are alternately opened and closed multiple times as shown in FIG. 4 to remove each bug 3 in the compartment 2a. By repeatedly contracting and expanding, the collected dust is brushed off.

After the collected dust is brushed off, the secondary damper 12a is closed, the pre-coat damper 18a is opened together with the secondary damper 6a, and the secondary high-temperature clean air inside the machine is drawn out via the duct 13 by the blower 14. ,
Iron oxide powder, which is a pre-coating agent, is supplied from the storage tank 17 by the cut-out device 16 and conveyed by air from the supply duct 15 into the lower hopper 4a. It is wrapped and collected on the filter cloth surface of each bag 3 in the compartment 2a, thereby forming a protective layer on the filter cloth surface of the bag 3. After that, the cutting device 16 and blower 14 are stopped, and the precoat damper 18
Close a, continue to introduce high-temperature dust-containing gas, and restart filtration and dust collection.

As a result, the same effects as in the above embodiment can be obtained, and efficient dust collection by the bag filter can be achieved.

In addition, in the case of this push-in type dust collector, as in the above embodiment, the protective layer is formed on the filter cloth surface of each bag 3 by introducing only clean air mixed with a pre-coating agent, without wrapping the dust-containing gas. It is possible to do so.

In addition to the above, each bag 3 uses a long-fiber filter cloth that has a good effect of removing collected dust, and further includes lower hoppers 4a to 4d for discharging the removed dust to the outside of the machine, and a It is also effective to forcibly insulate the conveyor (not shown) that transports the dust to the location using steam or other means to smoothly discharge and transport the dust.

Furthermore, in order to prevent the temperature inside the machine from dropping when the dust collector is stopped,
It is also effective to install a damper or shutter to block the intrusion of external cold air to the secondary side from the machine or the exit of the bug, or to cover the dust collector unit 1 and peripheral equipment (various ducts, etc.) with heat insulating material to keep them warm. It is.

〔Effect of the invention〕

As described above, when introducing dust-containing gas generated from hot metal pretreatment equipment, a pre-coating agent such as iron oxide powder is introduced in advance to protect the filter cloth from deliquescence caused by the dust-containing gas. A protective layer was formed by adhering it to the filter cloth surface, and then the dust-containing gas from the hot metal pretreatment equipment was introduced and filtered and collected by the protective layer on the filter cloth surface. It is possible to reliably prevent malfunctions such as moisture absorption and clogging of the filter cloth caused by deliquescence phenomenon, and it is possible to easily wipe off the collected dust and regenerate the filter cloth. Gas filtering and dust collection using a bag filter can be performed efficiently.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing one embodiment of a dust collector used in the dust collection method of the present invention, Fig. 2 is a time chart showing the operation of the same dust collector, and Fig. 3 is a diagram showing another embodiment of the dust collector. FIG. 4 is a time chart showing the operation of the dust collector. 1... Main body of the dust collector, 2a to 2d... Compartment chamber, 3.
...Bug (a cloth), 4a-4d...lower hopper, 5
...Dust-containing gas introduction duct, 6a to 6d... - next damper, 7... Exhaust duct, 8... Suction blower, 9... Backwash type collection dust removal mechanism, 10a
. 10d... Circulation damper, 11...
Backwash duct, 12a to 12d...Secondary damper, 1
3... Derivation duct, 14... Blower, 15... Supply duct, 16 Powder cutting device, 17... Precoat agent storage tank, 18a to 18d... Precoat damper, 20... 1 and Pull duct.

Claims (4)

[Claims] (1) In a method of filtering and collecting dust-containing gas generated from hot metal pretreatment equipment using a filter cloth, a pre-coat agent is introduced in advance to protect the filter cloth from the deliquescence phenomenon of the collected dust and adheres to the surface of the filter cloth. A method for collecting dust in a hot metal pretreatment facility, characterized in that the dust-containing gas from the hot metal pretreatment facility is introduced and filtered to collect the dust. (2) A dust collection method in a hot metal pretreatment facility according to claim 1, characterized in that iron oxide powder is used as a precoat agent. (3) The dust collection method in a hot metal pretreatment facility according to claim 2, wherein the iron oxide powder is collected by ventilation dust collection in a steelmaking converter or blast furnace cast bed dust collection. (4) The pre-coat agent is characterized in that high-temperature clean air from the secondary side of the dust collector is led out so as not to cool the filter cloth surface, and the pre-coat agent is introduced into the air to be supplied to the filter cloth surface. A method for collecting dust in hot metal pretreatment equipment according to claim 1 or 2.