JP5572934B2 - Vertical melting furnace exhaust gas treatment facility - Google Patents

Description

  The present invention relates to metal pieces, metal wires, coarse dust, plastics mixed in exhaust gas discharged from the top of a vertical melting furnace that produces pig iron using scrap and iron waste as a raw material. The present invention relates to an exhaust gas treatment facility having a function of removing foreign matters such as pieces in advance.

  Conventionally, in a vertical melting furnace, an iron source mainly composed of iron scrap, foundry scrap, pig iron, etc., which has a higher metallization rate than iron ore is melted to produce pig iron (Patent Documents 1 to 3, In recent years, however, there is a tendency to use a large amount of iron-making dust as an iron source. Steelmaking dust contains a lot of iron oxide and has a lower metallization rate than pig iron scrap. Therefore, in addition to the melting function to dissolve the iron source, the vertical melting furnace has a reduction function to reduce the iron oxide in the iron source. Is required.

  Against this background, in addition to iron sources that have a high metallization rate and do not require reduction, such as sintered process iron scrap, foundry scrap, pig iron, etc., dust agglomerates, self-reducing ores (carbon materials) Several methods of operating a vertical melting furnace using an iron source that has a low metallization rate and needs to be reduced, such as a high-content agglomerate), have been proposed (see Patent Documents 4 to 6).

  However, when the iron sources to be introduced into the vertical melting furnace are diversified, the substances that are mixed in unmelted in the exhaust gas discharged from the top of the furnace are diversified and the content thereof is increased. For example, a large amount of foreign matters such as metal pieces, metal wires, coarse dust particles, and plastic pieces are mixed in the exhaust gas. These foreign matters remain in the exhaust gas without being removed in the subsequent dust removal step, and inhibit the exhaust gas treatment. Therefore, a technique for efficiently removing these foreign substances is required.

  Patent Document 7 discloses a coke filling tank that allows exhaust gas to pass downstream of a temperature reducing tower that cools the exhaust gas discharged from the waste melting furnace, and a filtration type that collects the exhaust gas discharged from the coke filling tank. An exhaust gas treatment apparatus for a waste melting furnace in which a dust collector is disposed has been proposed.

  In the exhaust gas treatment apparatus described in Patent Document 7, coke in which dust in the exhaust gas is captured is supplied to the waste melting furnace as auxiliary fuel, and the dust is discharged from the waste melting furnace as slag. However, in the exhaust gas treatment apparatus, the amount of slag increases more than necessary, and hardly soluble dust accumulates in the exhaust gas treatment facility without being removed.

  Therefore, in recent years, in the operation of vertical melting furnaces, along with the diversification of iron sources, the exhaust gas is mixed with the exhaust gas, obstructing the exhaust gas treatment, and removing the foreign substances that cause the exhaust gas treatment equipment to break down or break down. Therefore, there is a need for a technology that removes it at an early stage.

Japanese Patent Application Laid-Open No. 07-109508 Japanese Patent Laid-Open No. 09-061058 JP-A-08-209111 Japanese National Publication No. 01-501401 Japanese Patent Application Laid-Open No. 10-036906 JP 09-203584 A JP 2003-28412 A

  The present invention is based on the fact that, in the operation of vertical melting furnaces, with the diversification of iron sources, there is a need for technology to remove foreign substances that are mixed in exhaust gas and impede exhaust gas treatment. It is an object of the present invention to provide an exhaust gas treatment facility having a function of efficiently removing foreign matters such as metal pieces, metal wires, coarse dust, and plastic pieces from an exhaust gas at an early stage.

  As described above, metal pieces, metal wires, coarse dust, plastic pieces, etc. cause exhaust gas treatment equipment failure or damage, clogging of circulating water channels in the dust removal equipment, and reduction of circulating water volume. It must be removed at an early stage of processing. Moreover, since the plastic piece causes generation of scum that gives off a bad odor, it is necessary to remove it at the initial stage of the exhaust gas treatment.

  The present inventors diligently studied a method for removing foreign matters at the initial stage of exhaust gas treatment. This invention was made | formed based on the result of the said examination, and the summary is as follows.

( 1 ) In an exhaust gas treatment facility provided with a dust removal device that sprinkles and removes dust from an exhaust gas of a vertical melting furnace, the exhaust gas inflow side conduit of the dust removal device includes a foreign matter removal device that removes foreign matters mixed in the exhaust gas, foreign matter removing apparatus, foreign matter discharge port, with a barrier to direct the exhaust gas flux in the conduit wall in the middle of the exhaust gas inlet-side pipe diameter exhaust pipe connected to the passage and an exhaust gas conduit, the bottom of the filtration apparatus Comb-type dust remover having a purification device for purifying accumulated dust-containing wastewater, wherein the purification device has a drainage basin for receiving dusty wastewater collected at the bottom of the dust removal device, and the drainage basin collects and removes plastic pieces exhaust gas treatment system of the vertical melting furnace you comprising: a.

(2) provided with a water circulation passage for circulating the purified water in the purifier in the filtration apparatus, according to the above (1), characterized in that it comprises a dust collector in which the water circulation passage to remove fine suspended dust circulating water Exhaust gas treatment facility for vertical melting furnace.

  According to the present invention, foreign substances (metal pieces, metal wires, coarse dust, plastic pieces, etc.) can be removed from the exhaust gas of the vertical melting furnace at the initial stage of the exhaust gas treatment. Can be done efficiently. Furthermore, according to this invention, the purification process of the dust containing waste_water | drain generated in a dust removal process can be performed efficiently.

  The present invention will be described with reference to the drawings.

  FIG. 1 shows a part of a conventional exhaust gas treatment facility. The dust removing device 18 includes a gas cooler 5, a gas suction fan 7, and a mist separator 8. The exhaust gas generated in the vertical melting furnace 1 is sucked into the gas cooler 5 from the gas suction port 4 through the exhaust gas conduit 3 connected to the exhaust gas suction part 2.

  The exhaust gas is coarsely dust-removed and cooled in the gas cooler 5 by watering from a watering nozzle 6 connected to the circulation water channel 10. The exhaust gas after rough dust removal and cooling is further subjected to water sprinkling 6a while passing through the exhaust gas pipe line 3a, and fine dust is removed while sucking the exhaust gas by the gas suction fan 7, and the mist is removed by the mist separator 8. Is done.

  The exhaust gas from which the fine dust and mist have been removed is burned and diffused 9a into the atmosphere as it is from the exhaust port 9, or used as a fuel gas 9b for another device (for example, a hot stove). The dust collected by the watering is accumulated in the bottom part 11 of the gas cooler 5 as dust-containing wastewater together with surplus water, and is intermittently sent to the sedimentation / separation tank 21 which is a purification device via the drainage channel 12.

  However, there is a limit to the dust removing ability by watering, and the dust removing device 18 shown in FIG. 1 cannot sufficiently remove foreign matters (metal pieces, metal wires, coarse dust, plastic pieces, etc.) in the exhaust gas. Therefore, the present inventors have intensively studied means for removing foreign substances in the exhaust gas.

  FIG. 2 shows an aspect of the exhaust gas treatment facility of the present invention. In FIG. 2, the same reference numerals (numerals) as those in FIG. In the exhaust gas treatment facility shown in FIG. 2, a foreign substance removing device 13 is disposed in the middle of the exhaust gas pipe 3 connecting the gas suction part 2 of the vertical melting furnace 1 and the gas suction port 4 of the gas cooler 5. Yes.

  The foreign matter removing apparatus 13 includes (a) a foreign matter discharge port 17 and an enlarged exhaust gas pipeline 14 connected to the exhaust gas pipeline 3, and (b) an exhaust gas pipeline 3 b connected to the gas suction port 4 of the gas cooler 5. The bottom 16 of the expanded exhaust gas conduit 14 and (c) the barrier 15 disposed at the center of the expanded exhaust conduit 14.

  After the exhaust gas flux entering the expanded exhaust gas pipe 14 from the exhaust gas pipe 3 collides with the barrier 15, the flux is pushed to the peripheral wall side of the expanded exhaust gas pipe 14. Thereafter, at this time, the foreign matter in the exhaust gas travels between the outer periphery of the exhaust gas conduit 3b and the peripheral wall of the expanded exhaust gas conduit 14 by inertia, collides with the bottom portion 16 and loses kinetic energy and falls. The exhaust gas discharged from the discharge port 17 and from which foreign matters have been removed is discharged toward the gas suction port 4 through the exhaust gas pipe line 3b (see arrows in the figure).

  Metal pieces, metal wires, coarse dust particles, plastic pieces, etc. are heavy and are completely removed by the foreign matter removing device 13. That is, the foreign substance removing device 13 can completely remove foreign substances that hinder the subsequent exhaust gas treatment and cause the failure or damage of the exhaust gas treatment apparatus at the initial stage of the exhaust gas treatment. This is a feature of the present invention.

  Light plastic pieces and fine dust may enter the dust removing device 18 without being removed by the foreign matter removing device, but are removed by watering in the dust removing device 18.

  FIG. 3 shows one mode of an exhaust gas treatment facility including a foreign substance removal device, a dust removal device, and a series of purification devices. The foreign matter removal in the foreign matter removing device 13 and the dust removal in the dust removing device 18 are as described above (see FIG. 2 and the description thereof). Here, the purification treatment of the dust-containing wastewater that accumulates in the bottom 11 of the gas cooler 5 will be described. In FIG. 3, the same reference numerals (numerals) as those in FIG.

  The dust-containing wastewater is continuously sent from the bottom 11 of the gas cooler 5 through the drainage channel 12 to the drainage basin 19. The drainage basin 19 is provided with a dust remover 19a (for example, a comb-type dust remover) that mechanically collects and removes plastic pieces captured by the dust remover 18. Therefore, the plastic that causes scum can be almost completely removed while the dust-containing waste water passes through the drain 19.

  The dust-containing waste water is accommodated in the aggregation tank 20. Here, a flocculant 20b (for example, an inorganic flocculant or a polymer flocculant) is added and stirred by the stirrer 20a, and dust components in the dust-containing wastewater are agglomerated. The drainage slurry containing the agglomerated dust component is sent to the next sedimentation tank 21 where the agglomerated dust component is settled and separated. The settled aggregated dust component is sent to the treatment preparation tank 24 by the discharge rotary blade 21b, and is sent to the filter press device 25 through the tank.

  If there is an agglomerated dust component due to plastic in the agglomerated dust component, it floats on the surface of the drainage as scum in the sedimentation separation tank 21. The floating scum is removed by the scum removing rotary blade 21a.

  In the case of an exhaust gas treatment facility that does not include the foreign substance removal device 13, a large amount of scum floats in the sedimentation separation tank 21, and the removal and treatment after removal is not easy. However, in the exhaust gas treatment facility of the present invention, the foreign matter removal device 13 is provided, the amount of scum that floats in the sedimentation tank 21 is reduced. Therefore, the scum removal rotary blade 21a may be rotated as necessary, and the processing after the removal is easy.

  The waste water from which the agglomerated dust component has been removed in the settling tank 21 is sent to the purification tank 22. Here, the water temperature of the waste water is lowered by the cooling device 26.

  The purified water is further processed in another purification treatment tank 23 to be used for another purpose, or is used as water for water spraying in the dust removing device 18 through the circulating water channel 10. It is desirable that the circulating water channel 10 is further provided with a dust remover in order to remove minute floating dust in the circulating water before watering.

  The exhaust gas treatment facility shown in FIG. 3 is an example, and the exhaust gas treatment facility of the present invention is not limited to this example.

  Next, examples of the present invention will be described. The conditions of the examples are one example of conditions adopted for confirming the feasibility and effects of the present invention, and the present invention is limited to this one example of conditions. Is not to be done. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

(Example)
Table 1 shows the results of treating the exhaust gas from the vertical melting furnace with the exhaust gas treatment facility of the present invention example shown in FIG. Table 1 also shows the results of treating the exhaust gas from the vertical melting furnace with a conventional (comparative) exhaust gas treatment facility that does not include a foreign substance removing device.

  In the invention example, before the exhaust gas treatment by the dust removing device, the foreign matter in the exhaust gas is removed by the foreign matter removing device, so that the cleaning frequency for removing the foreign matter in the dust removing device is reduced as compared with the comparative example not having the foreign matter removing device. Moreover, the fall of the circulating water amount by a foreign material obstruct | occluding a circulating water channel is also eliminated.

  In the present invention, since the frequency of cleaning for removing foreign matters in the dust removing device is reduced to once every two weeks, the operation of the vertical furnace for cleaning is eliminated, so The production rate has improved. Moreover, it turns out that the amount of scum (floating matter) and the amount of slurry dust (precipitate) which generate | occur | produce in a sedimentation-separation tank are reduced in the invention example compared with a comparative example.

  As described above, according to the present invention, foreign substances (metal pieces, metal wires, coarse dust, plastic pieces, etc.) can be removed from the exhaust gas of the vertical melting furnace at the initial stage of exhaust gas treatment. Subsequent exhaust gas treatment can be performed efficiently. Furthermore, according to this invention, the purification process of the dust containing waste_water | drain generated in a dust removal process can be performed efficiently. Therefore, the present invention has great applicability in the steel industry and the waste treatment industry.

It is a figure which shows the one part aspect of the conventional waste gas processing equipment. It is a figure which shows the one part aspect of the waste gas processing equipment of this invention. It is a figure which shows the one aspect | mode of the waste gas processing equipment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vertical melting furnace 2 Gas suction part 3, 3a, 3b Exhaust gas pipe 4 Gas suction port 5 Gas cooler 6 Sprinkling nozzle 6a Sprinkling 7 Suction fan 8 Mist separator 9 Exhaust port 9a Combustion discharge 9b Fuel gas 10 Circulation water channel DESCRIPTION OF SYMBOLS 11 Bottom part of gas cooler 12 Drainage channel 13 Foreign material removal apparatus 14 Expanded exhaust gas channel 15 Barrier 16 Exhaust gas channel bottom 17 Foreign material outlet 18 Dust removal device 19 Drainage tank 19a Dust remover 20 Aggregation tank 20a Stirrer 20b Aggregation Agent 21 Sedimentation separation tank 21a Scum removal rotor blade 21b Discharge rotor blade 22, 23 Purification treatment tank 24 Treatment preparation tank 25 Filter press device 26 Cooling device

Claims (2)

In an exhaust gas treatment facility equipped with a dust removal device that sprinkles and removes dust from the exhaust gas of a vertical melting furnace, a foreign matter removal device that removes foreign matter mixed in the exhaust gas is provided in the exhaust gas inflow side line of the dust removal device, and the foreign matter removal The apparatus includes a foreign substance discharge port, a large- diameter exhaust gas pipe connected to the exhaust gas inflow side pipe, and a barrier that directs the exhaust gas flux toward the pipe peripheral wall at the center of the exhaust gas pipe , and collects dust containing at the bottom of the dust removal apparatus comprising a purifying device for purifying waste water, comprising a gutter for receiving the dust-containing waste water the purifying device is accumulated on the bottom of the filtration apparatus, Ru includes a comb teeth type filtration apparatus which drainage gutter is removed by collecting the plastic pieces An exhaust gas treatment facility for a vertical melting furnace. 2. The vertical melting furnace according to claim 1 , further comprising a circulation water channel that circulates water purified by the purification device to a dust removal device, and the circulation water channel includes a dust remover that removes minute floating dust in the circulation water. Exhaust gas treatment equipment.

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