JPS6136160Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a scrap preheating device using electric furnace exhaust gas, which removes white smoke and strange odors that are hydrocarbon gases generated during scrap preheating, and
The present invention relates to the provision of an apparatus aimed at achieving highly efficient preheating treatment.

Conventionally, a scrap preheating device using electric furnace exhaust gas has a heat storage chamber that introduces high-temperature waste gas from the electric furnace through a primary duct; and a part or all of the high-temperature waste gas in the heat storage chamber that is also introduced through a preheater duct. and a preheater bucket charged with scrap for preheating; the preheater bucket is connected to the preheater bucket, and the preheated waste gas after heat exchanged with the scrap charged in the bucket is released into the atmosphere. It consists of a dust collector for discharging;

In the above configuration, the charged scrap is heated in direct contact with the waste gas in the preheater bucket, and foreign substances such as oil, rubber, and vinyl contained in the scrap are incompletely combusted.
The waste gas will inevitably contain white smoke and strange odors.

In response to the above problem, the following improvements have recently been made to the above conventional structure. That is, a recycle duct is provided to guide the preheated waste gas from the preheater bucket to the primary duct, and a recycle duct is formed near the confluence of the primary duct and the recycle duct to direct the combustion air of the preheated waste gas into the primary duct. It is provided with an air inlet for introducing air, and is further provided with an exhaust duct for discharging the high temperature waste gas in the heat storage chamber to the outside,
By circulating the waste gas after preheating the scrap into the heat storage chamber and burning it, the preheated waste gas is completely combusted, and a portion of the high-temperature waste gas in the heat storage chamber is released to the outside through the exhaust duct. .

However, even with this configuration, the following problems have been pointed out.

First, since cold air from the outside is introduced through the air inlet, the temperature of the waste gas flowing into the preheater bucket decreases, which is not preferable in terms of preheating treatment.

Further, this introduced air occupies, for example, half of the air volume processed by the exhaust gas blower, which is undesirable because it increases the load on the blower.

Second, because the temperature of the air introduced from the air inlet is low, white smoke in the preheated waste gas after preheating treatment,
It is not possible to obtain a sufficient temperature to burn off the off-flavor components.

Thirdly, since the introduced air and the preheated waste gas cannot be sufficiently mixed, the combustion of the preheated waste gas becomes insufficient.

Fourth, by introducing external air through the air inlet, the ability of the exhaust gas blower to suck high-temperature waste gas from the electric furnace decreases, which impedes high-efficiency operation of the electric furnace.

The present invention was devised to solve these conventional problems, and its features include: a heat storage chamber into which high-temperature waste gas from the electric furnace is introduced via a primary duct; and a preheater duct. A preheater bucket into which high-temperature waste gas in the heat storage chamber is introduced through and into which scrap for preheating is charged; a recycling duct which leads preheated exhaust gas from the preheater bucket to the primary duct; a primary duct; an air inlet that is formed near the confluence of the recycle duct and introduces combustion air for preheated waste gas into the primary duct; an exhaust duct that discharges high-temperature waste gas in the heat storage chamber to the outside; an injector that directs a flow of preheated waste gas in a direction that intersects and interferes with the air flow to regulate the amount of air introduced.

Embodiments of the present invention will be described below with reference to the drawings. High-temperature waste gas from the electric furnace 1 is introduced into the heat storage chamber 3 via the primary duct 2. The high-temperature waste gas in the heat storage chamber 3 is introduced into a preheater bucket 5 through a preheater duct 4 lined with a refractory for heat-resistant insulation, and the bucket 5 is charged with scrap for preheating. . The preheater bucket 5 is removably installed in a preheating pit 6, and a preheating waste gas duct 7 is connected to the preheating pit 6, that is, the preheater bucket 5. The preheated waste gas duct 7 is branched into a discharge duct 8 and a recycling duct 9, and the discharge duct 8 supplies the preheated waste gas from the preheated waste gas duct 7 to a dust collector 10 and an exhaust blower 1.
1 to the outside of the equipment, that is, to the atmosphere, and the recycling duct 9 is connected to the preheated waste gas duct 7
The preheated waste gas is guided from the duct to the primary duct 2, and a recycle fan 12 is provided in the middle of the duct.

An air introduction port 13 for introducing combustion air for preheated waste gas into the primary duct 2 is formed near the confluence of the primary duct 2 and the recycling duct 9 . That is, the primary duct 2 connects to the furnace lid 14 of the electric furnace 1.
A water cooling duct 17 is separably connected to the elbow 15 via a sliding pipe 16, and a gap between the elbow 15 and the water cooling duct 17 is connected to the air inlet 13. The recycling duct 9 is connected to the sliding pipe 16 and the air inlet 1.
The outside air is introduced into the primary duct 2 through the gap between the hood 18 and the elbow 15 and the air inlet 13.

The sliding tube 16 is externally fitted onto both the elbow 15 and the water cooling duct 17 so as to be slidable in the axial direction, and is driven by a cylinder (not shown). is said to be adjustable. Further, the gap between the hood 18 and the elbow 15 is configured to be dimensionally adjustable, while the space between the hood 18 and the water cooling duct 17 is sealed. The discharge duct 8 and the recycling duct 9 are provided with dampers 19 and 20, respectively, which can be opened and closed, and the discharge duct 8 and the heat storage chamber 3 are connected by an extension of the discharge duct 8, and the preheater duct 4 and the discharge duct are connected to each other by an extension of the discharge duct 8. Dampers 22 and 23, which can be opened and closed, are respectively provided at the extensions of 8.

The dampers 19, 20, 22, 23 allow part or all of the waste gas to pass therethrough in an adjustable manner.
In order to regulate the amount of air introduced from the air inlet 13, an injector 25 directs the preheated waste gas flow in a direction that interferes with this air flow, that is, in a direction that crosses the primary duct 2 and the recycling duct 9.
It is formed at the confluence of the

The injector 25 has a hood 18 that covers the sliding tube 16 that is fitted onto the water cooling duct 17 so as to be slidable in the axial direction.
The recycling duct 9 is a cylindrical body provided on the same axis as the hood 18, and one end of the recycling duct 9 is connected to the outer circumference of the hood 18, and the hood 18 is connected to the elbow 15 in the axial direction.
At the end of the direction, a flange 15a at the free end of the elbow 15
A gas outlet 27 is formed which is oriented toward the surface and radially inward. In addition, the flange 15a
Air is introduced into the water cooling duct 17 from the gap between the gas outlet 27 and the air inlet 13 . A pair of baffle plates 28, 28 are installed at the connection between the recycle duct 9 and the hood 18, and distribute the preheated waste gas in the recycle duct 9 evenly in the circumferential direction of the hood 18. spout 27
distribute evenly.

Next, the operation of the above embodiment will be explained.

The high-temperature waste gas generated in the electric furnace 1 is transferred to the elbow 15,
It passes through the water cooling duct 17 into the heat storage chamber 3 and is distributed to the preheater duct 4 and the extension of the discharge duct 8. The waste gas introduced into the preheater duct 4 preheats the scrap charged in the preheater bucket 5, and then passes through the preheated waste gas duct 7, the recycling duct 9, and returns to the hood 18.

This refluxed preheated waste gas is mixed with external air necessary for combustion that enters through the gap between the hood 18 and the elbow 15, and is introduced into the primary duct 2, that is, the water cooling duct 17 through the air inlet 13. .

In this case, the water cooling duct 1 passes through the air inlet 13 from the gap between the flange 15a and the gas outlet 27.
7, the air introduced into the gas outlet 27 crosses and interferes with the preheated waste gas ejected from the gas outlet 27, and the amount of air introduced is regulated to the minimum necessary amount, and the preheated waste gas and air are sufficiently mixed. A good mixture can be obtained. Since only the required amount of low-temperature outside air (about 25°C) can be introduced, the inlet temperature of the preheater bucket 5 is maintained at about 500 to 600°C. In addition, the temperature at the mixed combustion position of the preheated waste gas and the waste gas from the electric furnace is approximately 600 to 800 degrees Celsius, and this temperature increases the hydrocarbon gas that is the component of the odor and white smoke after preheating the scrap. This is the temperature at which complete combustion and removal is achieved.

Furthermore, by reusing preheated waste gas and regulating the introduction of external air to a minimum, the exhaust suction capacity of waste gas from the electric furnace remains almost unchanged, which has a significant impact on the high efficiency operation of electric furnace 1. Never. Therefore, the highly efficient and completely combusted waste gas is again distributed to the preheater duct 4 and the extension of the exhaust duct 8 for preheating, and the waste gas in the extension of the exhaust duct 8 is passed through the dust collector 10. and is released into the atmosphere. In this case, since the waste gas released into the atmosphere finally passes through the heat storage chamber 3, the combustion is more complete and the generation of secondary pollution is prevented.

Please note that the scrap for preheating is of good quality, i.e.
If it does not contain flammable substances such as oil or rubber, the dampers 20 and 23 on the extensions of the recycling duct 9 and discharge duct 8 are closed, and the preheater duct 4 is closed.
The dampers 22 and 19 of the exhaust duct 8 are opened, and the entire amount of high-temperature waste gas discharged from the electric furnace 1 is introduced into the preheater bucket 2, thereby achieving highly efficient heat recovery without causing secondary pollution. You can also.

Figure 4 is a graph showing the components of the preheated waste gas immediately after preheating the scrap in a 50Ton electric furnace.02% is at least ₁₆ % or more, and this preheated waste gas can be used sufficiently for combustion. That is understood. Therefore, as described above, when the preheated waste gas is returned to the primary duct 2, the combustion of combustible substances in the waste gas can be promoted instead of or together with the external air.

According to the present invention, the injector 25 allows
The amount of air introduced from the air inlet 13 is regulated, and the preheated waste gas is reused for preheating the scrap, preventing the temperature of the waste gas from flowing into the preheater bucket 5 and reducing heat. Recovery is achieved with high efficiency. In addition, since the introduced air and the waste gas from the recycling duct 9 intersect and are sufficiently mixed, combustion efficiency is increased, preheating treatment is effective, and white smoke and odor components are sufficiently combusted. This will prevent secondary pollution from occurring. Furthermore, since the amount of air introduced from the outside is reduced, the power of the exhaust blower can also be reduced, which is beneficial.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, FIG. 1 is a schematic explanatory view of the whole, FIG. 2 is a partially enlarged sectional view of FIG. 1,
FIG. 3 is a sectional view taken along the - line arrow in FIG. 2, and FIG. 4 is a graph showing the components of the preheated waste gas immediately after preheating the scrap. 1... Electric furnace, 2... Primary duct, 3... Heat storage chamber, 4... Preheater duct, 5... Preheater bucket, 8... Discharge duct, 9... Recycling duct, 13... Air Inlet port, 25...injector.

Claims (1)

[Scope of utility model registration request] A heat storage chamber 3 into which high-temperature waste gas from the electric furnace 1 is introduced through a primary duct 2;
A preheater bucket 5 loaded with scrap for preheating; a recycling duct 9 that leads preheated exhaust gas from the preheater bucket 5 to the primary duct 2; the primary duct 2 and the recycling duct 9.
An air inlet 13 is formed near the confluence of the two and introduces the combustion air of the preheated waste gas into the primary duct 2.
and an exhaust duct 8 that discharges high-temperature waste gas in the heat storage chamber 3 to the outside; and a preheated exhaust gas flow in a direction that intersects and interferes with this air flow in order to regulate the amount of air introduced from the air inlet 13. A scrap preheating device using electric furnace exhaust gas, comprising: an injector 25 for directing;