JPS6229708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scrap preheating device that recovers high-temperature exhaust gas heat from a steelmaking furnace and utilizes it for scrap preheating.

Conventionally, the exhaust gas that has undergone scrap heating using the heat of the high-temperature exhaust gas from a steelmaking furnace is sent to a dust collector via a cooling tower, and the gas separated from fine dust is released into the atmosphere. However, when preheating the scrap,
It may contain hydrogen sulfide, acetaldehyde, styrene, and other strong-smelling harmful gas components generated from low-grade scrap, and if these are released into the atmosphere as they are, there is a risk of secondary pollution.

For this reason, for example, as shown in Figure 1, the fan
The first containing unburned gas components from the arc furnace AF at F ₁
The secondary high-temperature exhaust gas (hereinafter referred to as primary exhaust gas) is sent to the combustion tower.
The low-temperature secondary exhaust gas (hereinafter referred to as secondary exhaust gas) containing the harmful gas components absorbed into the BT and recovered from the scrap preheater SPH by the fan F ₂ is sent again to the combustion tower BT, where it is deodorized by combustion. There is an example in which the gas is sent through a gas cooling tower CT to a dust collector S, where it is separated from fine dust, and the gas is released into the atmosphere.

In this case, for example, from the arc furnace AF to the combustion tower BT
absorbs primary exhaust gas of approximately 800 to 1200℃ and sends half of it to the scrap preheating device SPH to preheat the scrap to approximately 200 to 400℃.The secondary exhaust gas recovered from the scrap preheating device SPH is approximately 150 to 300℃. The temperature has fallen to ℃. When the secondary exhaust gas heated in this way is sent to the combustion tower BT again, the 1
This results in lowering the exhaust gas temperature, making it impossible to ensure the reaction temperature required for combustion deodorization of the harmful gas components, such as approximately 350°C or higher for hydrogen sulfide, approximately 400°C or higher for acetaldehyde, and approximately 600°C or higher for styrene. Complete deodorization is difficult. Discharging such gas into the atmosphere through the gas cooling tower CT and dust collector S is not effective in completely preventing secondary pollution.

In this invention, the secondary exhaust gas containing the harmful gas components generated by scrap preheating is mixed with the primary exhaust gas to which oxygen-containing gas is added, and then completely combusted to deodorize the harmful gas components and released into the atmosphere. The purpose of the present invention is to provide a scrap preheating device for discharging.

The gist of this invention is that (a) a combustion tower, a gas cooling tower, and a fan are arranged in this order between a steelmaking furnace and a dust collector;
These are connected by pipes, (b) an oxygen-containing gas source pipe is connected to the pipe connecting the steelmaking furnace and the combustion tower, and (c) a pipe is connected between the combustion tower and the gas mixing tower. A scrap preheating device is provided and these are connected by pipes, and (d) a pipe branched from the pipe connecting the steelmaking furnace and the combustion tower is connected to the gas cooling tower via the gas mixing tower. The scrap preheating device is characterized in that it is configured with a pipe opening/closing means for changing the route of the exhaust gas from the steelmaking furnace.

The configuration of this inventive device will be explained below with reference to the embodiment shown in FIG. In the figure, AF is an arc furnace, A is an oxygen-containing gas source (hereinafter referred to as an oxygen source),
BT is combustion tower, CT is gas cooling tower, S is exhaust tower ET
SPH is a scrap preheating device, M is a gas mixing tower equipped with an auxiliary burner MB,
F ₁ and F ₂ are a large fan and a small fan, respectively.

Next, connect the pipe T ₀ branched from the pipe T ₁ connecting the arc furnace AF and the combustion tower BT to the oxygen source A, and similarly connect the pipe T ₁₀ to the gas mixing tower M, and connect the pipe T 1 to the combustion tower BT. Scrap preheating device SPH, small fan
Between F ₂ and gas mixing tower M are pipes T ₆ ,
Connected at T ₇ , T ₈ , and T ₉ . Also, gas mixing tower M
and the gas cooling tower CT are connected by a conduit _T11 , and the conduit _T8 and the conduit _T11 are connected by a conduit _T12 . Furthermore, the combustion tower BT and the gas cooling tower
The CT, large fan F ₁ , and dust collector S are connected through pipes T ₂ , T ₃ , and T ₄ , respectively.

The conduit _T2 is provided with a conduit opening/closing means _V1 capable of opening and closing the conduit T2, the conduit _T10 is provided with a conduit opening/closing means _V2 , and the conduit _T12 is provided with a conduit opening/closing means _V2 . road opening/closing means
V ₃ , and a pipe opening/closing means V ₄ between pipe T ₈ and pipe T ₉
is provided. In addition, each pipe opening/closing means V ₁ to _{V 4}
consists of a valve or damper. Then, each pipe opening/closing means is opened and closed in accordance with the case where the scrap is not preheated, when the high grade scrap is preheated, and when the low grade scrap is preheated.
It is possible to form an exhaust gas path suitable for each.

Next, the operation of this inventive device will be explained.

1 If the scrap is not preheated, open the pipe opening/closing means _V1 and
By closing V ₂ , V ₃ and V ₄ , the steelmaking furnace AF
From combustion tower BT, gas cooling tower CT, large fan F ₁
A path leading to the dust collector S is formed.

As a result, oxygen-containing gas is transferred from the oxygen source A to the primary exhaust gas containing unburned gas components, such as CO, which is being sucked through the pipe line 1 from the electric arc furnace AF operating with the large fan _{F1 .} and add. Next, this primary exhaust gas is transferred to the total combustion tower BT.
and is completely combusted within this combustion tower BT. Thereafter, this primary exhaust gas is cooled in the cooling tower CT, passes through the large fan F ₁ , the dust collector S, and the exhaust tower ET and is released into the atmosphere.

2 When preheating high-grade scrap Open the pipeline opening/closing means V ₂ and V ₃ and close the pipeline opening/closing means V ₁ and V ₄ to connect the steelmaking furnace AF to the combustion tower BT, the scrap preheating device SPH, and the gas cooling Tower CT, large fan F ₁ and dust collector S
A path from the steelmaking furnace AF to the gas mixing tower M to the gas cooling tower CT is formed.

As a result, oxygen-containing gas is transferred from the oxygen source A to the primary exhaust gas containing unburned gas components, such as CO, which is being sucked through the pipe line 1 from the electric arc furnace AF operating with the large fan _{F1 .} and add. Next, a part of this primary exhaust gas is sucked in by a small fan _F2 , introduced into the combustion chamber BT, and after complete combustion, passes through the pipe _T6 to the scrap preheating device.
The high-grade scrap, which is introduced into the SPH and does not generate harmful gas components, is preheated to a predetermined temperature range.
At this time, the primary exhaust gas corresponding to the difference between the amount of primary exhaust gas sucked by the large fan F ₁ and the amount of primary exhaust gas sucked by the small fan F ₂ via the combustion tower BT is transferred to the pipe T _{10 .} The gas is introduced into the gas mixing column M from there. On the other hand, since the secondary exhaust gas sucked from the scrap preheating device SPH by the small fan F ₂ does not contain the harmful gas components, it is guided to the pipe T ₁₁ through the pipes T ₇ , T ₈ , and T ₁₂ , It is mixed with the primary exhaust gas derived from the gas mixing tower M and introduced into the gas cooling tower CT. Next, the mixed gas of the primary exhaust gas and the secondary exhaust gas is cooled in a gas cooling tower CT, and is cooled by a large fan F ₁ ,
It passes through the dust collector S and the exhaust tower ET and is released into the atmosphere.

3 When preheating low-grade scrap Open the pipe opening/closing means V ₂ and V ₄ and close the pipe opening/closing means V ₁ and V ₃ to connect the steelmaking furnace AF to the combustion tower BT, the scrap preheating device SPH, and the gas mixture. A path leading to the dust collector S via the tower M, the gas cooling tower CT, and the large fan _F1 , and a path leading from the steelmaking furnace AF to the gas mixing tower M are formed.

As a result, oxygen-containing gas is transferred from the oxygen source A to the primary exhaust gas containing unburned gas components, such as CO, which is being sucked through the pipe line 1 from the arc furnace AF operating with the large fan _F1 . ₀ and add. Next, a part of this primary exhaust gas is sucked by a small fan F ₂ and introduced into the combustion chamber BT, and after complete combustion, it is introduced into the scrap preheating device SPH through the pipe T ₆ , and the harmful gas components are removed. Preheat the generated low-grade scrap to a predetermined temperature range.
At this time, the primary exhaust gas corresponding to the difference between the amount of primary exhaust gas suctioned by the large fan F ₁ and the amount of primary exhaust gas suctioned via the combustion tower BT sucked by the small fan F ₂ is transferred from the pipe T ₁₀ . Gas mixing tower M
will be introduced in If the temperature of the primary exhaust gas passing through the pipe _T10 is lower than the predetermined temperature range, it is combusted by the auxiliary burner MB. On the other hand, the secondary exhaust gas sucked from the scrap preheating device SPH by the small fan F ₂ contains the harmful gas components, so it passes through the pipes T ₇ , T ₈ , and T ₉ to the gas mixing tower M.
Guide to. Therefore, as a result of mixing and burning the primary exhaust gas and the secondary exhaust gas in the gas mixing tower M, the harmful gas components contained in the secondary exhaust gas are also deodorized by combustion. This mixed gas is then passed through the pipe
After passing through T ₁₁ , it is introduced into the gas cooling tower CT and its temperature is lowered.
It passes through the large fan F ₁ , the dust collector S, and the exhaust tower ET and is released into the atmosphere.

In addition, in the above embodiment, a small fan F ₂ is installed in the pipe T ₇ .
Instead, a flow rate adjustment valve was installed at the connection position between pipe T ₁ and pipe T ₁₀ to create a negative pressure difference between pipe T ₁ and pipe T ₁₀ . However, this invention is effective. Further, although a pipe line 12 was provided for passing the secondary exhaust gas only during preheating of high-grade scrap, there is no problem even if this pipe line _T12 is abolished and the gas is guided to the gas mixing tower M.

As described above, the device of the present invention has the configuration of the pipe lines between each device element and the pipe opening/closing means, and is therefore ideal for not preheating scrap, for preheating high grade scrap, and for preheating low grade scrap. The equipment configuration can be implemented to allow efficient equipment operation and scrap preheating without passing exhaust gas through unnecessary equipment. Furthermore, by providing the oxygen-containing gas source, complete combustion of the primary exhaust gas can be ensured regardless of the amount of unburned gas components in the primary exhaust gas. The secondary exhaust gas containing harmful gas components generated in the scrap preheating device and the primary exhaust gas containing unburned gas components such as CO are mixed in a gas mixing tower, and then completely combusted and deodorized. This gas mixture is then released into the atmosphere from the gas cooling tower, dust collector, and exhaust tower, but it is characterized by the fact that no secondary pollution occurs.

[Brief explanation of the drawing]

Figure 1 is a layout diagram of a conventional scrap preheating device.
FIG. 2 is a layout diagram of the scrap preheating device of the present invention. AF... Steelmaking furnace, S... Dust collector, BT... Combustion tower, CT... Gas cooling tower, F... Fan, A...
...Oxygen-containing gas source, SPH...scrap preheater, M...gas mixing tower, T...pipe line.

Claims (1)

[Claims] 1 (a) A combustion tower, a gas cooling tower, and a fan are arranged in this order between the steelmaking furnace and the dust collector, and these are connected through pipes, and (b) The steelmaking furnace and the combustion tower are connected. A pipe line for an oxygen-containing gas source is connected to the pipe line, (c) a scrap preheating device is provided between the combustion tower and the gas mixing tower and these are connected to each other by a pipe line, and (d) the steel manufacturing tower A pipe branching from a pipe connecting the furnace and the combustion tower is connected to the gas cooling tower through a gas mixing tower, and a pipe opening/closing means is provided for changing the exhaust gas route from the steelmaking furnace. A scrap preheating device characterized by: