JPS61257410A - Operating method for converter waste gas treatment device - Google Patents

Abstract

PURPOSE:To expedite the time for recovering of gaseous CO and to increase the recovery rate thereof by starting the control in a converter and lowering the skirt thereof after the flow rate of the converter waste gas having the components of the specific value or below of the concns. of CO or O2 therein attains a prescribed flow rate. CONSTITUTION:The skirt 1 is raised and the CO in the waste gas is burned to generate the inert gaseous CO2 in the stage of starting refining by blowing oxygen through an oxygen blowing lance 12 to the molten iron introduced into the converter in a converter waste gas treatment device which sucks the waste gaseous CO generated from the converter 1 by an induced draft fan 7 and recovers the same as a valuable gas through a hood 3, a cooler 4 and dust removers 5, 6 via a duct 9 into a gas holder (not shown). <=12.5% concn. of CO or 5.5% concn. of O2 in the waste gas is thereafter detected by a gas analyzing instrument 13 in the outlet of the cooler 4 and a damper 16 is adjusted to start the control of the pressure in the furnace after the flow rate of the gas having the above-mentioned components attains the prescribed flow rate. The lowering operation of the skirt 2 is executed at the same instant to start recovering the gaseous CO.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method of operating a converter exhaust gas treatment apparatus that increases the total recovery amount of CO gas generated during blowing.

(Prior art and its problems) During refining, a large amount of high-temperature CO gas is generated from the converter. This CO gas is an extremely dangerous gas because there is a risk of explosion if it comes into contact with the outside air, and furthermore, it can cause carbon monoxide poisoning if it leaks outside. Further, this CO gas is recovered as a valuable gas by a converter exhaust gas treatment device.

To explain the outline of the converter exhaust gas treatment device using FIG. 2, the CO gas generated from the converter 1 is drawn into the hood 3 by the induced fan 7, cooled by the cooler 4, and then passed through the dust remover. 5 and 6, and is passed through the duct 9 and collected as valuable gas into a gas boulder (not shown).

In this converter exhaust gas treatment device, the converter operation is performed as follows.

First, hot metal produced in a blast furnace (not shown) is charged into a converter 1. That is, the skirt 2 is raised, the converter 1 is tilted, and hot metal is charged into the converter 1 (hereinafter referred to as the pig iron receiving process). After this pig iron receiving process is completed, the converter 1 is stood upright, the skirt 2 is lowered, and the space between the converter 1 and the hood 3 is sealed.

Next, pure oxygen is blown into the converter l from the oxygen injection lance 12 (hereinafter referred to as blowing) to start refining. Through this blowing, carbon (C) in the hot metal and pure oxygen (0)
As a result, high-temperature COO20 is generated and the carbon in the hot metal is decarburized, resulting in high-quality steel.

In addition, since the CO concentration is low at the beginning of blowing and at the end of blowing, the damper 10 is switched, the CO passes through the entire stripping tower 8, and is combusted and diffused at the top. What is recovered is the part with high CO concentration at the peak of blowing.

The blowing is performed in this manner, and the refined molten steel is taken out of the converter 1 (hereinafter referred to as tapping). In the case of this tapping, the skirt 2 is raised and the converter 1 is tilted, as in the case of receiving pig iron.

In the above-mentioned pig iron receiving and tapping processes, the lower end of the hood 3 is opened, so outside air is sucked in by the induced blower 7, and the exhaust gas treatment device is filled with outside air. If full blowing is started in this state, an explosion will occur due to contact with the outside air filling the COO20 device, so this explosion is usually prevented as follows. That is, at the start of blowing, the skirt 2 is raised to create a certain gap between it and the furnace opening of the converter 1, and the outside air is sucked through this gap, and the gas with a low CO concentration at the initial stage of blowing is removed. Burns to produce inert CO2 gas.

By generating inert CO2 gas in this way,
First, CO2 gas is interposed between the outside air that filled the device and the COO20 generated by blowing, and a gas layer in the form of CO gas → CO2 gas → outside air is formed in the exhaust gas device, COO20 prevents explosions by preventing direct contact with outside air. Below C above
The 02 gas (inert) layer is called an inert gas layer.

Also, in the final stage of blowing, in order to avoid contact with the preceding COO 20 and the subsequently sucked in outside air, the gas with a low CO concentration at the final stage of blowing is combusted to generate an inert gas layer.

In the converter operation mentioned above, the risk of explosion has been
Therefore, the timing of the rise of the skirt (at the end of blowing) or the time of fall of the skirt (in the beginning of blowing) was controlled with sufficient empirical timing to generate inert gas. That is, in the early stage of blowing, the skirt was lowered several seconds after the start of blowing, and the core 14 was raised several seconds before the end of blowing to generate an inert gas layer.

However, recently there has been a demand for recovering as much COO20 as possible. For these reasons, the amount of inert gas should be reduced as much as possible, and C
The reality is that there is an urgent need to develop operating methods for converter exhaust gas treatment equipment to increase the amount of OO20 recovered.

(Object of the invention) The present invention has been made in view of the above circumstances, and is
It is an object of the present invention to provide a method for operating a converter exhaust gas treatment device that can increase the recovery amount.

(Structure of the Invention) The operating method of the converter exhaust gas treatment equipment of the present invention is that, at the start of blowing, the skirt is not completely lowered in anticipation of safety based on the timing based on experience, as is the case in the past. Therefore, the minimum amount of inert gas necessary for this purpose is determined, and from the moment the determined desired amount of inert gas is reached, the inside of the furnace is controlled to recover COO20. At the outlet of the cooler, the CO concentration or 02 concentration in the exhaust gas is analyzed and the gas flow rate is measured, and the flow rate of an inert gas with a CO concentration of 12.5% or less and an 02 concentration of 5.5% or less reaches a predetermined flow rate. After reaching this point, the skirt is completely lowered and the pressure inside the furnace is controlled to recover 20 COO.

(Example) An example of the operating method of the converter exhaust gas treatment apparatus of the present invention will be described in detail. Figure 1 shows the amount of gas generated at the furnace mouth at the start of blowing (A), the 02 concentration at that time (D), and C.
The relationship between the O concentration (E) and the induced gas amount of the induced blower 7 is shown.

In the figure, at the same time as blowing starts, the amount of gas at the furnace mouth (converter mouth) (
02 concentration (D) decreases as A) increases, while C
O concentration (E) increases 0 No explosion 02 concentration and CO concentration are experimentally determined to be 5.5% or less for 02 and 12.5% for CO.
It is known that the following is sufficient. .

Lines c and c' in the figure indicate the range of the induced gas amount of the induced blower 7 necessary for generating inert gas with respect to the amount of gas generated at the furnace mouth (A) K.

That is, the concentration of the above O2 and Co gas is within the range of 5.5% or less and 12.5% or less, respectively, with respect to the induced gas amount of the induced blower 7 shown by line B''. One hour later, the opening degree of the damper 16 shown in Fig. 2 was adjusted according to the amount of gas generated at the furnace mouth (A), and the induced gas i of the induced fan 7 was throttled down as shown by line B'. Therefore, the amount of inert gas is as shown in (b).

In this embodiment, the amount of inert gas is set in advance to a minimum amount (a) sufficient for explosion prevention, and the amount of inert gas is set to 5.
5%, Co concentration is 12.5% (range of lines C and C'), when the measured gas flow rate reaches exactly (a) (67 hours from the start of blowing), the graph shown in Fig. 2 The opening degree of the damper 16 shown in FIG.

Next, a more detailed explanation will be given using FIGS. 1 and 2. At the start of blowing, the skirt 2 is raised. Further, the damper 16 is fully opened, and the gas generated at the furnace mouth is combusted by the outside air sucked from between the skirt 2 and the converter 1.
The total gas amount of this combustion gas and excess outside air becomes the rated suction amount (B'') of the induced blower 7 and flows through the processing device.

This surplus outside air is used for combustion of the gas generated at the furnace mouth and decreases as the amount of gas generated at the furnace mouth (A) increases.
quantity decreases. Subsequently, when the amount of gas generated at the furnace mouth (A) increases, the amount of outside air becomes insufficient, and a part of the gas generated at the furnace mouth cannot be completely combusted, c.

concentration increases.

In this way, changes in the 02 concentration and Co concentration at the initial stage of blowing are detected by the gas analyzer 13 installed at the outlet of the cooler 4, while the gas amount at this time is measured by the gas flow meter 14 and The signal is input to the device 15.

In the above gas analyzer, 021s degree is 5.5% or less,
When the CO# degree is 12.5% or less and the gas flow rate reaches a predetermined flow rate, the skirt 2 is lowered by the operating device 15, the suction of outside air is cut off, and the space between the converter l and the hood 3 is sealed. At the same time, the opening degree of the damper 16 is adjusted to adjust the induced gas amount (B) of the induced blower 7 in accordance with the amount of gas generated at the furnace mouth (A).
) is adjusted, the furnace pressure is controlled, and the recovery of Co gas is started. In this case, the amount of inert gas layer produced will be the amount (a) shown in Figure 1, and the collection time of Co gas will be:
It is t hours after the start of blowing.

As is clear from FIG. 1, the Co gas recovery time is advanced by 1-1 hours compared to the conventional one hour delay, and the amount of Co gas recovered increases by that amount.

(Effects of the Invention) As detailed above, in the operating method of the converter exhaust gas treatment apparatus of the present invention, at the start of blowing, the COg degree is analyzed and the COg degree is 12.5% or less.

02 When the concentration becomes an inert gas of 5.5 inches or less, the minimum amount of inert gas required to be reduced is measured using a gas flow meter, and after the specified gas flow rate is reached, the skirt 1 is lowered to completely shut off outside air. Since the pressure inside the furnace is fully controlled, Co
The gas recovery period can be brought forward, the amount of Co gas recovered as a valuable gas can be greatly increased, and this has a great industrial effect in terms of resource conservation.

[Brief explanation of drawings]

FIG. 1 is an embodiment of the present invention, and is a diagram showing the relationship between the amount of gas generated at the furnace mouth, the amount of gas induced by the induced blower, the 02 concentration, and the Co concentration in the early stage of blowing. FIG. 2 is an embodiment of an exhaust gas treatment apparatus for carrying out the entire method of the present invention, and is a diagram showing a schematic configuration thereof. 1... Converter 2... Skirt 7... Induced blower 12... Oxygen blowing lance 13... Gas analyzer 14... Flow rate meter 15... Operator 16... Pressure Symbol explanation of the control damper in Fig. 1 A...Amount of gas generated at the furnace mouth B...Induced gas in the induced blower in/...Amount of induced gas in the conventional induced blower
B"...Rated induced gas amount of induced blower D...0
2 Concentration E... CO concentration (a)... Amount of inert gas produced in this example (b)... Amount of conventional inert gas produced

Claims (1)

[Claims] C in the exhaust gas at the outlet of the cooler of the converter exhaust gas treatment equipment
Analyzing the O concentration or O_2 concentration and measuring the gas flow rate, the CO concentration is 12.5% or less and the O_2 concentration is 5.5%.
1. A method for operating a converter exhaust gas treatment apparatus, which comprises starting control of the furnace pressure and lowering the skirt after the gas flow rate of the following components reaches a predetermined flow rate.