JPS6173808A - Operating method of waste gas treating device for converter - Google Patents

Abstract

PURPOSE:To stabilize a converter operation in a waste gas treating device for a converter by determining preliminarily plural set values corresponding to the gaseous pressure in the converter, measuring periodically the pressure in the converter during the actual operation and making the process for restoring the pressure in the converter so as not to exceed the set values. CONSTITUTION:The body of the converter 1 and a skirt 4 for waste gas are brought into tight contact with each other by an outside seal 5. Pure oxygen is blown through a top blowing lance 3 to the molten iron 2 to oxidize and refine the molten iron 2 by which the molten steel is produced. The pressure of the waste gas in the hood 4 is periodically detected at specified periods by an in-furnace pressure detector 6. Pural stages of the set values are prelimiarily provided to the gaseous pressure in the converter and when the value detected by the detector 6 exceeds each stage of the set value, various adjusting devices including an electro-hydraulic controller 13 are operated to restore the pressure near the atm. pressure so as to meet the set values by which the unstability in the converter condition owing to the increase or decrease in the gaseous pressure in the furnace is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to Which the Invention Pertains] The present invention relates to a furnace pressure compensation method in a converter waste gas treatment device (OG).

[Prior art and its problems]

Conventional converter waste gas treatment equipment operates without bringing the skirt located above the furnace mouth into close contact with the furnace mouth. Therefore, the furnace pressure is approximately positive.

It was within the range of minus number va H20 (water column).

However, when operating with the skirt lowered and the furnace mouth in close contact, or in a similar manner, if large disturbances occur for some reason, the furnace pressure can reach plus or minus several hundred 1 Hz O, and as a result, the converter waste gas treatment equipment This is also an unfavorable result from the standpoint of protecting the main body. For example, this may cause the gas seal device to break, or excessive stress may be applied to the duct body.

[Purpose of the invention]

This invention has been made in view of this point, and when the furnace internal pressure falls outside the range of each set value, it compensates the furnace internal pressure to fall within a predetermined range by performing corresponding processing, The purpose is to ensure its safety.

[Key points of the invention]

This invention provides a converter waste gas treatment system in which a plurality of set values corresponding to the furnace pressure are determined in advance in order to suppress the furnace internal pressure within a predetermined range, and the furnace internal pressure is monitored at regular intervals. When this exceeds each set value, the corresponding furnace pressure recovery process is performed.

[Embodiments of the invention]

The figure is a configuration diagram showing an example of a converter waste gas treatment apparatus for which the present invention will not be explained in detail. In the figure, ■ is a converter, 2 is hot metal and scrap, 3 is a top blowing lance, 4 is a skirt, 5 is an outer seal, 6 is a furnace pressure transmitter, 7 is a hood, and 8 is N2 (nitrogen) for control. Valve, 9 is air intake valve, 1
0 is the upper safety valve, 11-1 is the primary dust collector, 11-2 is the 2
12 is a damper, 13 is an electrohydraulic control device, 4 is a bypass valve, 15 is a induced fan ([DF), 16 is a furnace internal pressure control device, and 17 is an emergency N2 valve.

Scrap and hot metal 2 are charged as main raw materials into a converter 1, and high pressure oxygen is blown into the top of the converter using a lance 3 to refine the hot metal into /8 steel. This is called blowing. During blowing, oxygen combines with carbon in the hot metal to generate waste gas mainly composed of CO gas. This waste gas has a temperature of approximately 1200℃
It has a high temperature of 150 g/Nm, and contains a large amount of iron oxide dust. Since this waste gas is high temperature,
In order to protect the main body of the apparatus, the hood part 7 is water-cooled with a water-cooled pipe. On the other hand, in order to remove dust from this waste gas, a primary dust collector (IDr, ) + 1-1. A secondary dust collector (2DC) 11-2 is provided.

Since these dust collectors use dust collecting water, the waste gas is rapidly cooled down to a temperature of about 70°C.

In order to remove dust from waste gas, it is necessary to pass the gas at high speed through the two dust collectors mentioned above, and each dust collector 11-1, 11-2 is equipped with a damper 12, It is a mechanism. In addition, gas suction is done using an induced fan (IDF).
It is carried out by 15. The gas pressure at the furnace mouth is called furnace pressure (furnace pressure), and is detected by the furnace pressure detector 6, and is also detected by the furnace pressure control device 16 to the secondary collector B 11-2.
It is controlled by moving the damper 12 inside. In addition,
An electro-hydraulic control machine 13 is normally used as a drive device for this damper. This furnace pressure is usually controlled close to atmospheric pressure,
Gas may blow out from the gap between the furnace mouth and the skirt 4,
The amount of air sucked in is minimized as much as possible. Usually, the gap between skirt 4 and furnace mouth is 200+
If it is in the n position, the furnace pressure is plus or minus several m++ H
It is controlled between 20. However, when the skirt 4 is lowered and a device called the outer seal 5 that brings the skirt into close contact with the furnace body is operated, there is almost no gap at the furnace mouth. increases, and during abnormalities, it increases to plus or minus several hundred mm Hz.
It can be O. For this reason, it is common for the furnace internal pressure control device 16 to be devised in various ways to improve controllability. However, if there is a very large disturbance, such as a sudden increase or decrease in the gas m generated in the furnace, the pressure in the furnace will suddenly increase or decrease.

Therefore, in this invention, the abnormal positive pressure in the furnace,
In order to prevent abnormal negative pressure, several set values (hereinafter also referred to as hand widths) are set for the pressure in the furnace, and when this hand width is exceeded, the furnace is stopped by performing processing corresponding to each hunt width. Allow the internal pressure to return to the atmospheric pressure level.

An example of the pressure recovery operation method of the present invention will be described below. Note that symbols PHH3 to PLL3 indicate respective setting values.

(a) When the pH exceeds (becomes) 83, open the upper safety valve 10 provided in the OG duct, release the gas in the duct to the outside, and lower the pressure inside the furnace.

(b) When PHH2 is exceeded, the skirt 4 is raised by I am, the gas inside the furnace is released to the outside, and the pressure inside the furnace is lowered.

(c) When PHHI is exceeded, the skirt 4 is raised by Ham (H<I), the gas inside the furnace is released to the outside, and the pressure inside the furnace is lowered.

(d) When the pH exceeds 3, open the shutoff valve 14 provided in the duct that bypasses the secondary dust collector (2DC) 11-2, and allow the gas before the secondary dust collector to flow after the secondary dust collector ( By bypassing), the gas at the furnace mouth is reduced and the pressure inside the furnace is lowered. Note that the same operation can be performed in the primary dust collector 11-1 instead of the secondary dust collector 11-2.

(E) When PH2 is exceeded, the operating end (2DC damper) 12 that controls the furnace internal pressure is set to Δ
Open by the opening of KI4H to release the gas in front of the secondary precipitator and lower the pressure inside the furnace.

(to) When PH1 is exceeded, ΔK11 (ΔKll<ΔK, In) as with PH2
Open the furnace by the opening degree of , lowering the pressure inside the furnace.

(g) When PLl is exceeded (below), PH2, P
Contrary to the process H1, the 20C damper 12 is closed by the opening degree Δ, the flow path of the secondary dust collector 11-2 is narrowed, and the furnace pressure is increased.

(H) When PL2 is exceeded, similarly to PLI, close □ to □ to increase the furnace pressure.

(S'') When PL3 is exceeded, the control N2 valve 8 is opened at the furnace mouth through piping with a relatively narrow flow path, and NZ (nitrogen gas) is blown into the furnace mouth to increase the amount of gas inside the furnace mouth.
Increase the furnace pressure.

(v) When the PLLO is exceeded, the outer seal 5 is opened, air is sucked into the furnace mouth from the outside, the amount of gas inside the furnace mouth is increased, and the pressure inside the furnace is raised.

(l) When the PLLI is exceeded, the skirt 4 is raised by Hm, air is sucked into the furnace mouth from the outside, the amount of gas inside the furnace mouth is increased, and the pressure inside the furnace is raised.

(E) When PLL2 is exceeded, the skirt 4 is raised by lam, air is sucked into the furnace mouth from the outside, the amount of gas inside the furnace mouth is increased, and the pressure inside the furnace is raised.

In addition, the emergency N2 valve 17 of the piping with a relatively wide flow path provided above the furnace mouth is opened and N2 is blown in to raise the pressure inside the furnace. Furthermore, the air suction valve 9 at the top of the furnace mouth is opened to suck in air from outside and increase the pressure inside the furnace.

(W) When PLL3 is exceeded, the induced fan (IDF) 15 is stopped to prevent a decrease in gas in the furnace mouth and duct, and to suppress a drop in furnace pressure.

In this way, depending on the value of the pressure inside the furnace, the gas inside the furnace mouth and inside the duct is increased or decreased as appropriate to restore the pressure. The table below summarizes the correspondence between the furnace internal pressure set value and the pressure recovery process as described above.

〔Effect of the invention〕

According to this invention, when the pressure in the furnace becomes abnormally high or low, depressurization treatment is performed according to each stage from treatment with low depressurization capacity to treatment with high depressurization capacity, depending on the value of the pressure in the furnace at that time. As a result, the operation of the plant (converter waste gas treatment equipment) can be continued as much as possible, and damage to the plant can be prevented.

[Brief explanation of drawings]

The figure is a plant explanatory diagram of a converter waste gas treatment apparatus for explaining the present invention in detail. Code explanation 1... Converter, 2... Scrap, hot metal, 3... Top blowing lance, 4... Skirt, 5... Outer seal, 6
... Furnace pressure transmitter, 7 ... Hood section, 8 ... N2 valve for control, 9 ... Air intake valve, 10 ... Upper safety valve, 11-1 ... Primary dust collector , 11-2...Secondary dust collector, 12...Damper, 13...Electro-hydraulic control machine, 14.
...2DC bypass valve, 15...induced blower, 16.
...Furnace pressure control device, 17...Emergency N2 valve.

Claims (1)

[Claims] In a converter waste gas treatment system that collects and processes waste gas from a converter by keeping the converter mouth and skirt sealed or in a substantially equivalent state, the pressure inside the converter is monitored at predetermined intervals. On the other hand, multiple set values for the furnace internal pressure are set in advance in stages, the detected furnace pressure is compared with each set value, and depending on which set value the detected furnace internal pressure exceeds, a corresponding action is taken. 1. A method of operating a converter waste gas treatment apparatus, characterized in that a predetermined furnace pressure recovery process is performed to adjust the increase or decrease of waste gas.