WO2021131089A1 - Exhaust gas treatment device for electric furnace - Google Patents

Abstract

The present invention is provided with: an electric furnace for melting scrap materials; a post-burning device for causing unburnt components included in an exhaust gas discharged from the electric furnace to be burnt; a cooling device for cooling the hot exhaust gas after the unburnt components have been burnt; a dust collecting device for removing dust included in the exhaust gas after being cooled; and a heat storage gas treatment device which is provided with two or more heat storage chambers that contain heat storage materials, and in which while the exhaust gas from which the dust has been removed is guided in a heated state to a burning unit through the heat storage chambers in which the heat storage materials are in a heated state, and burnt, and hazardous components in the exhaust gas are decomposed, the heat of the exhaust gas burnt in the burning unit is stored by the heat storage materials contained in the other heat storage chamber to discharge the exhaust gas.

Description

Exhaust gas treatment equipment for electric furnaces

The present invention relates to an exhaust gas treatment device for an electric furnace that treats exhaust gas discharged from the electric furnace. In particular, when scrap materials are melted in an electric furnace to produce recycled metals, the exhaust gas emitted from this electric furnace contains a large amount of dust, unburned components, odors, dioxins, and other harmful components. It is characterized in that it can be effectively processed at low cost.

Conventionally, scrap materials have been melted in an electric furnace to produce recycled metals.

Here, impurities such as paints, oils, and resins are present in the scrap material, and when the scrap material is dissolved in an electric furnace in this way, various harmful components are generated in the exhaust gas. It is included.

For this reason, when exhausting the exhaust gas generated in the electric furnace, conventionally, harmful components contained in the exhaust gas have been treated and discharged.

Here, in treating the harmful components contained in the exhaust gas discharged from the electric furnace, in the one shown in Patent Document 1, the combustion towers are in order from the upstream of the exhaust path for guiding the exhaust gas discharged from the electric furnace. , A burner deodorizing tower, a cooling tower, a bag house (bug filter) as a dust collector, and a mixing tower equipped with an activated carbon charging device are installed.

Then, in the case of Patent Document 1, after burning an unburned component such as CO contained in the exhaust gas with a burner in the combustion tower, the exhaust gas is swirled in the burner deodorizing tower. A plurality of burners are provided along the exhaust gas path to be sent so as to cause combustion, and the flame of each burner decomposes odorous components such as oil in the exhaust gas.

Next, the exhaust gas deodorized by the burner deodorizing tower is guided to the cooling tower to be cooled to a predetermined temperature, and the exhaust gas cooled in this way is guided to the bag house (bug filter), and the exhaust gas in the bag house (bug filter). After collecting the dust inside, this exhaust gas is guided to the mixing tower, and the activated carbon is blown into the swirling flow from the activated carbon input device while swirling in the mixing tower, and the burner deodorizing tower cannot completely decompose the exhaust gas. It is designed to adsorb and remove harmful components such as dioxin.

However, in Patent Document 1, as described above, unburned components such as CO contained in the exhaust gas are burned by the burner in the combustion tower, and a plurality of burners are burned in the burner deodorizing tower to cause odor. Although the components are decomposed, the exhaust gas discharged from the two furnaces is released to the atmosphere as it is, so that the heat at the time of combustion is not effectively used and the fuel cost is high.

Furthermore, since various odorous components that could not be completely decomposed in the burner deodorizing tower are removed by charging activated carbon from the activated carbon charging device in the mixing tower, the device as a whole becomes large and costly. As described above, there is a problem that it is necessary to dispose of activated carbon on which harmful components such as dioxins are adsorbed.

Japanese Unexamined Patent Publication No. 2005-138608

The present invention is an exhaust gas treatment device for an electric furnace that treats exhaust gas discharged from an electric furnace that melts scrap materials, and includes various types of dust, unburned components, odors, dioxin, etc. contained in the exhaust gas discharged from the electric furnace. It is an object of the present invention to enable effective treatment of harmful components of the above at low cost.

In the exhaust gas treatment device of the electric furnace according to the present invention, in order to solve the above-mentioned problems, an electric furnace for melting scrap materials and combustion for burning unburned components contained in the exhaust gas generated in the electric furnace are used. A means, a dust collecting device for removing dust contained in the exhaust gas after burning unburned components, and two or more heat storage chambers containing a heat storage material are provided, and the exhaust gas derived from the dust collecting device is provided. Is guided to the combustion part while being heated through the heat storage chamber where the heat storage material is heated to decompose the harmful components contained in the exhaust gas, while the heat of the exhaust gas burned in the combustion part is used for other parts. A heat storage type gas treatment device for discharging exhaust gas through another heat storage chamber is provided so that heat is stored in the heat storage material housed in the heat storage chamber.

Then, in the exhaust gas treatment device of the electric furnace in the present invention, after burning the unburned components contained in the exhaust gas generated in the electric furnace by the combustion means, the exhaust gas is guided to the dust collector and contained in the exhaust gas. The dust is removed by a dust collector, and the exhaust gas after removing the dust is guided to the above-mentioned heat storage type gas treatment device provided with two or more heat storage chambers containing a heat storage material and contained in the exhaust gas. Try to break down harmful components. In this way, by guiding the exhaust gas after removing the dust to the heat storage type gas treatment device to decompose the harmful components contained in the exhaust gas, it is possible to prevent the heat storage material contained in the heat storage chamber from being clogged with dust. At the same time, the exhaust gas guided from the dust collector is heated through the heat storage chamber in which the heat storage material is heated, and the exhaust gas heated in this way is guided to the combustion part and burned, and is contained in the exhaust gas. While the harmful components are sufficiently decomposed, the exhaust gas that is burned in this way and the harmful components are decomposed is guided to another heat storage chamber, and the harmful components are decomposed into the heat storage material housed in the other heat storage chambers. The heat of the exhaust gas is stored, and the heat of the exhaust gas after burning so that the harmful components contained in the exhaust gas are decomposed in the combustion part is effectively used, and the temperature of the exhaust gas from which the harmful components are decomposed is used. Will be able to be discharged into the atmosphere in a reduced state.

Here, in the exhaust gas treatment device of the electric furnace of the present invention, the exhaust gas guided to the dust collector is cooled at a position before the exhaust gas after burning the unburned component is guided to the dust collector. It is preferable to provide a cooling device. In this way, if a cooling device for cooling the exhaust gas after burning the unburned components is provided at a position before being guided to the dust collector, the temperature of the exhaust gas guided to the dust collector is lowered and the dust collector is provided. It is not necessary to use an expensive ceramic bag filter or the like, and it is also possible to absorb fluctuations in the temperature of exhaust gas from an electric furnace.

Here, in the exhaust gas treatment apparatus of the electric furnace of the present invention, as the combustion means for burning the unburned component contained in the exhaust gas generated in the electric furnace, the exhaust gas guided from the electric furnace through the exhaust gas guide pipe is used. A combustion device for burning can be provided.

Further, as the combustion means, an unburned component concentration sensor for measuring the concentration of unburned components contained in the exhaust gas guided from the electric furnace to the exhaust gas guide pipe, and at least oxygen gas supplied into the electric furnace to generate electricity. An internal combustion device for burning the unburned component contained in the exhaust gas in the furnace is provided, and the unburned component gas is supplied to the internal combustion device based on the concentration of the unburned component gas measured by the unburned component concentration sensor. The amount of oxygen gas can be controlled.

In the exhaust gas treatment device of the electric furnace in the present invention, after burning the unburned components contained in the exhaust gas generated in the electric furnace by the combustion means as described above, this exhaust gas is guided to the dust collector to exhaust gas. The dust contained in the exhaust gas is removed by a dust collector, and the exhaust gas after the dust is removed is guided to the above-mentioned heat storage type gas treatment device provided with two or more heat storage chambers containing a heat storage material, and is contained in the exhaust gas. The harmful components contained in the above are decomposed.

As a result, in the exhaust gas treatment device of the electric furnace in the present invention, by using the heat storage type gas treatment device and the dust collection device, it is possible to prevent the heat storage material housed in the heat storage chamber from being clogged with dust and to collect dust. The exhaust gas derived from the dust device is heated (preheated) through the heat storage chamber in which the heat storage material is heated, and the exhaust gas heated in this way is guided to the combustion part and burned, and is harmful contained in the exhaust gas. While the components are sufficiently decomposed, the exhaust gas that is burned in this way and the harmful components are decomposed is guided to another heat storage chamber, and the exhaust gas that the harmful components are decomposed into the heat storage material housed in the other heat storage chambers. The heat is stored and can be used for heating (preheating) the exhaust gas, and the temperature of the exhaust gas in which harmful components are decomposed is lowered and discharged in a state, and the harmful components contained in the exhaust gas in the combustion part The heat of the exhaust gas after burning it so that it can be decomposed will be effectively used.

It is a schematic explanatory drawing which showed the use state of the exhaust gas treatment apparatus of the electric furnace in one Embodiment of this invention. (A) and (B) show a state in which the heat storage type gas treatment device is used in the exhaust gas treatment device of the electric furnace in the above embodiment, and the heat storage material is heated with the exhaust gas guided from the dust collector. It is heated through one of the heat storage chambers in the state of being in a state and guided to the combustion part, and the heated exhaust gas is burned in the combustion part to decompose harmful components contained in the exhaust gas, while the heat of the exhaust gas burned in the combustion part is dissipated. It is the schematic explanatory drawing which showed the state which performed the operation which exhausts exhaust gas through a heat storage chamber alternately so that heat is stored in the heat storage material housed in the other heat storage chamber. It is the schematic explanatory drawing which showed the use state of the exhaust gas treatment apparatus of the electric furnace which concerns on other embodiment of this invention.

Hereinafter, the exhaust gas treatment device for the electric furnace according to the embodiment of the present invention will be specifically described with reference to the attached drawings. The exhaust gas treatment device for the electric furnace according to the present invention is not limited to the one shown in the following embodiment, and can be appropriately modified and implemented without changing the gist of the invention.

In the exhaust gas treatment device of the electric furnace according to the first embodiment, as shown in FIG. 1, the electric furnace 10 for melting the scrap material S and the exhaust gas generated in the electric furnace 10 are guided through the exhaust gas guide pipe P1. The post-combustion device 20, which is a combustion means for burning the unburned components contained in the exhaust gas, and the high-temperature exhaust gas after burning the unburned components are guided through the exhaust gas guide pipe P2 to control the temperature of the exhaust gas. A dust collecting device 40 including a cooling device 30 for lowering the temperature, an exhaust gas whose temperature has been lowered by the cooling device 30 is guided through an exhaust gas guide pipe P3, and a bag filter for removing dust contained in the exhaust gas, and the above-mentioned collecting device. The exhaust gas after the dust is removed by the dust device 40 is guided through the exhaust gas guide pipe P4, and a heat storage type gas treatment device 50 for decomposing various harmful components such as odor and dioxin contained in the exhaust gas is provided.

Here, in the electric furnace 10, as shown in FIG. 1, above the scrap supply pipe 11 extending upward so as to branch from the exhaust gas guide pipe P1 extending upward from the upper part of the electric furnace 10. Is provided with an input port 12 for supplying the scrap material S into the electric furnace 10, and an opening / closing member (not shown) provided under the input port 12 is opened / closed to supply the scrap material S from the inside of the input port 12. The scrap material S is charged into the electric furnace 10 through the scrap supply pipe 11 and the exhaust gas guide pipe P1 of the above, and the scrap material S thus charged is melted by the electrode 14 provided in the electric furnace 10 and carbon is charged into the electric furnace 10. Carbon is supplied through a supply pipe (not shown) to adjust the composition. Here, when the scrap material S in the charging port 12 is charged into the electric furnace 10 through the scrap supply pipe 11 and the exhaust gas guide pipe P1 extending upward from the upper part of the electric furnace 10 as described above, the scrap material is charged. While S is being charged into the electric furnace 10, it is preheated by the heat of the high-temperature exhaust gas generated in the electric furnace 10, and the electric power energy when the scrap material S is melted in the electric furnace 10 can be reduced. ..

Then, the exhaust gas generated when the scrap material S is melted in the electric furnace 10 as described above is guided to the post-combustion device 20 through the exhaust gas guide pipe P1, and then the combustion burner (FIG. (Not shown) is provided, and the unburned components contained in the exhaust gas guided from the electric furnace 10 through the exhaust gas guide pipe P1 are burned by this combustion burner to remove the unburned components from the exhaust gas.

Next, a water spray device (not shown) is provided in the cooling device 30 in which the high-temperature exhaust gas thus removed by burning the unburned components by the post-combustion device 20 is guided through the exhaust gas guide pipe P2, and the water spray device is provided. Water is sprayed into the cooling device 30 to lower the temperature of the high-temperature exhaust gas guided into the cooling device 30, and the exhaust gas whose temperature is lowered by the cooling device 30 is discharged from the exhaust gas guide pipe P3. It is guided to the dust collecting device 40 through the dust collecting device 40, and the dust contained in the exhaust gas is removed by the dust collecting device 40. Here, in this embodiment, since the high-temperature exhaust gas obtained by burning and removing the unburned component is guided to the cooling device 30 for cooling, the dust collector 40 is made of an expensive ceramic having excellent heat resistance. It is not necessary to use a manufactured bag filter or the like, and an inexpensive filter can be used. When a ceramic bag filter having excellent heat resistance is used for the dust collector 40, the high-temperature exhaust gas can be guided as it is, or the cooling device 30 can be omitted.

Further, the cooling device 30 may be an air-cooled system instead of the water-cooled system that sprays water as described above.

Then, the exhaust gas from which the dust has been removed by the dust collector 40 as described above is guided to the heat storage type gas treatment device 50 through the exhaust gas guide pipe P4, and the odor contained in the exhaust gas is generated in the heat storage type gas treatment device 50. After decomposing various harmful components such as dioxin, the exhaust gas obtained by decomposing the harmful components is exhausted from the heat storage type gas treatment device 50 through the blower 60.

Here, in the heat storage type gas treatment device 50 in this embodiment, as shown in FIGS. 1 and 2 (A) and 2 (B), two heat storage chambers 51 and 52 in which the heat storage material X is housed, respectively. A combustion unit 54 provided with a combustion burner 53 is provided above the two heat storage chambers 51 and 52 so as to communicate with the heat storage chambers 51 and 52, and fuel gas is supplied to the combustion burner 53. A fuel gas supply pipe 53a to be supplied is connected, and an air supply flow path 53b for supplying combustion air is provided around the combustion burner 53.

Further, in the heat storage type gas treatment device 50 of this embodiment, the exhaust gas from which the dust guided through the exhaust gas guide pipe P4 has been removed is placed under the two heat storage chambers 51 and 52. Exhaust gas supply pipes 55a and 55b for supplying to the heat storage chambers 51 and 52 are provided, and damper type switching valves 56a and 56b for opening and closing these are provided inside the exhaust gas supply pipes 55a and 55b, respectively.

Then, the switching valves 56a and 56b provided inside the exhaust gas supply pipes 55a and 55b are alternately switched to open and close, and the exhaust gas from which the dust guided through the exhaust gas guide pipe P4 has been removed is replaced with the switching valve 56a. , 56b is guided through the exhaust gas supply pipes 55a and 55b on the open side to one of the heat storage chambers 51 and 52 in which the heat storage material X is housed as described above, and the exhaust gas thus guided is referred to the heat storage. The heat is heated by the heat storage material X stored in the chambers 51 and 52 and guided to the combustion unit 54, and the exhaust gas heated as described above is burned by the combustion burner 53 provided in the combustion unit 54 to be in the exhaust gas. It is designed to decompose harmful components such as odor and dioxin remaining in the air. Since the exhaust gas from which the dust has been removed is guided to the heat storage type gas treatment device 50, the heat storage material X housed in each of the heat storage chambers 51 and 52 is blocked by the dust contained in the exhaust gas. Never.

Further, as described above, the exhaust gas obtained by decomposing harmful components such as odor and dioxin remaining in the exhaust gas in the combustion unit 54 is exhausted through the heat storage chambers 51 and 52 in which the heat storage material X is housed as described above. In the heat storage type gas treatment device 50 of this embodiment, exhaust gas exhaust pipes 57a and 57b are provided under the heat storage chambers 51 and 52, respectively, and these are opened and closed inside the exhaust gas exhaust pipes 57a and 57b. The damper type switching valves 58a and 58b for performing the above are provided, respectively.

Then, the switching valves 58a provided inside the exhaust gas exhaust pipes 57a and 57b provided under the heat storage chambers 51 and 52 different from the heat storage chambers 51 and 52 to which the exhaust gas from which the dust has been removed as described above are supplied. , 58b were opened, and the opening and closing of the switching valves 58a and 58b provided inside the exhaust gas exhaust pipes 57a and 57b were alternately switched, and combustion treatment was performed to decompose harmful components such as odor and dioxin. The exhaust gas is guided to the heat storage chambers 51 and 52, which are different from the heat storage chambers 51 and 52 to which the exhaust gas is supplied, and is guided to the stored heat storage material X to store the heat of the combustion-treated exhaust gas, and the temperature of the exhaust gas is described. The exhaust gas guided through the exhaust gas exhaust pipes 57a and 57b in which the switching valves 58a and 58b are opened is exhausted by the blower 60 through the exhaust pipe 57 to which the exhaust gas exhaust pipes 57a and 57b merge. I am trying to do it.

In this way, the combustion treatment by the combustion burner 53 provided in the combustion unit 54 allows the harmful components such as odor and dioxin remaining in the exhaust gas to be sufficiently decomposed, and the harmful components such as odor and dioxin are sufficiently decomposed. It is possible to prevent the exhaust gas from being exhausted while remaining in the exhaust gas, and the heat during the combustion process that decomposes harmful components such as odor and dioxin remaining in the exhaust gas is stored in the heat storage chambers 51 and 52 described above. The heat is stored in the heat storage material X and is effectively used, and the temperature of the exhaust gas exhausted by the blower 60 can be lowered.

In the heat storage type gas treatment apparatus 50 of this embodiment, only two heat storage chambers 51 and 52 in which the heat storage material X is housed are provided as described above, but more heat storage chambers (FIG. FIG. It is also possible to provide (not shown).

Next, the exhaust gas treatment device of the electric furnace in another embodiment will be described.

In the exhaust gas treatment device of the electric furnace according to the other embodiment, the exhaust gas treatment device of the electric furnace according to the first embodiment and the combustion means for burning the unburned components contained in the exhaust gas generated in the electric furnace 10. I'm just changing.

Here, in the exhaust gas treatment device of the electric furnace in this embodiment, as shown in FIG. 3, at least oxygen gas is supplied as a combustion means for burning the unburned components contained in the exhaust gas generated in the electric furnace 10. An internal combustion device 70 for burning the unburned components contained in the exhaust gas in the electric furnace 10 is provided, and the upper part of the electric furnace 10 merged with the scrap supply pipe 11 for supplying the scrap into the electric furnace 10. In addition to the exhaust gas guide pipe P1 extending to the above, a bypass guide pipe 71 is provided to guide the exhaust gas in the electric furnace 10 to the portion of the exhaust gas guide pipe P1 branched from the scrap supply pipe 11, and this bypass guide is provided from the inside of the electric furnace 10. The concentration of the unburned component gas contained in the exhaust gas guided to the exhaust gas guide pipe P1 through the pipe 71 is measured by the unburned component concentration sensor 72.

Then, the concentration of the unburned component gas contained in the exhaust gas guided from the inside of the electric furnace 10 measured by the unburned component concentration sensor 72 to the exhaust gas guide pipe P1 through the bypass guide pipe 71 as described above is output to the combustion gas control device 73. Then, the combustion gas control device 73 controls the amount of oxygen gas in the gas supplied to the internal combustion device 70 in accordance with the concentration of the unburned component gas measured by the unburned component concentration sensor 72. A gas having a controlled amount of oxygen gas is supplied to the internal combustion device 70 and burned in the electric furnace 10, and the unburned component gas contained in the exhaust gas is burned in the electric furnace 10.

Further, as the internal combustion device 70, in this embodiment, a combustion burner that forms a flame is shown, but an oxygen lance that supplies only oxygen gas may be used.

Therefore, in the exhaust gas treatment device of the electric furnace in this embodiment, the post-combustion device 20 in the first embodiment is eliminated, and the exhaust gas from which the unburned component gas is eliminated as described above is guided to the exhaust gas. It is designed to lead directly to the cooling device 30 through the pipe P1.

After that, also in this embodiment, the temperature of the exhaust gas obtained by burning the unburned component gas by the cooling device 30 is lowered in the same manner as the exhaust gas treatment device of the electric furnace in the first embodiment. The exhaust gas whose temperature has been lowered is guided to the dust collecting device 40 through the exhaust gas guide pipe P3, the dust contained in the exhaust gas is removed by the dust collecting device 40, and then the exhaust gas from which the dust has been removed is exhaust gas. It is guided to the heat storage type gas treatment device 50 through the guide pipe P4, and in this heat storage type gas treatment device 50, various harmful components such as odor and dioxin contained in the exhaust gas are decomposed, and the exhaust gas obtained by decomposing the harmful components in this way is decomposed. The heat storage type gas treatment device 50 is exhausted through the blower 60.

Here, also in this embodiment, as in the first embodiment, the dust collector 40 is used to guide the high-temperature exhaust gas from which the unburned components are burned and removed to the cooling device 30 for cooling. It is not necessary to use an expensive ceramic filter or the like having excellent heat resistance, an inexpensive filter can be used, and when a ceramic filter having excellent heat resistance is used for the dust collector 40. It is also possible to guide the high-temperature exhaust gas as it is and not to provide the cooling device 30.

10: Electric furnace 11: Scrap supply pipe 12: Input port 14: Electrode 20: Post-combustion device (combustion means)
30: Cooling device 40: Dust collecting device 50: Heat storage type gas processing device 51: Heat storage chamber 52: Heat storage chamber 53: Combustion burner 53a: Fuel gas supply pipe 53b: Air supply flow path 54: Combustion unit 55a: Exhaust gas supply pipe 55b : Exhaust gas supply pipe 56a: Switching valve 56b: Switching valve 57: Exhaust gas 57a: Exhaust gas exhaust pipe 57b: Exhaust gas exhaust pipe 58a: Switching valve 58b: Switching valve 60: Blower 70: Internal combustion device (combustion means)
71: Bypass guide pipe 72: Unburned component concentration sensor 73: Combustion gas control device P1: Exhaust gas guide pipe P2: Exhaust gas guide pipe P3: Exhaust gas guide pipe P4: Exhaust gas guide pipe S: Scrap material X: Heat storage material

Claims (4)

An electric furnace that melts scrap materials, a combustion means that burns unburned components contained in the exhaust gas generated in the electric furnace, and a dust collector that removes dust contained in the exhaust gas after burning the unburned components. Then, two or more heat storage chambers in which the heat storage material is housed are provided, and the exhaust gas derived from the dust collector is guided to the combustion unit in a state of being heated through the heat storage chamber in which the heat storage material is heated. While burning and decomposing harmful components contained in the exhaust gas, the heat of the exhaust gas burned in the combustion part is stored in the heat storage material housed in the other heat storage chamber, and the exhaust gas is discharged through the other heat storage chamber. An exhaust gas treatment device for an electric furnace, which is characterized by being equipped with a heat storage type gas treatment device for combustion. In the exhaust gas treatment device of the electric furnace according to claim 1, cooling for cooling the exhaust gas guided to the dust collector at a position before guiding the exhaust gas after burning the unburned component to the dust collector. An exhaust gas treatment device for an electric furnace, which is characterized by being provided with a device. In the exhaust gas treatment apparatus of the electric furnace according to claim 1 or 2, the exhaust gas guided from the electric furnace through the exhaust gas guide pipe as a combustion means for burning the unburned components contained in the exhaust gas generated in the electric furnace. An exhaust gas treatment device for an electric furnace, which is characterized by being provided with a combustion device for combusting. In the exhaust gas treatment apparatus of the electric furnace according to claim 1 or 2, as a combustion means for burning unburned components contained in the exhaust gas generated in the electric furnace, the exhaust gas guided from the electric furnace to the exhaust gas guide pipe is used. An unburned component concentration sensor that measures the concentration of unburned components contained and an internal combustion device that supplies at least oxygen gas into the electric furnace to burn the unburned components contained in the exhaust gas in the electric furnace are provided. An exhaust gas treatment device for an electric furnace, characterized in that the amount of oxygen gas supplied to the internal combustion device is controlled based on the concentration of the unburned component gas measured by the unburned component concentration sensor.

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