JPS62297410A - Control method for recovery of og gas of converter - Google Patents

Abstract

PURPOSE:To prevent the deterioration of calorie in CO gas and the combustion of blown-out gas from skirt part by measuring N2 concentration in OG gas for a converter by gas analyzer and controlling the exhaust gas flowing rate in accordance with a deviation between the measured value and the setting value. CONSTITUTION:Raw materials 2 are charged into the converter 1 and refining oxygen 4 is blown, and then carbon in the raw materials 2 is reached with the oxygen 4 and CO concentration in the OG gas 9 becomes to about 70-80%. When the pressure in the hood part 6 becomes to equal to the initial setting value (almost atmospheric pressure) and reaches a regular condition, three-way valve 20 is changed to recovery valve 21 side and controlling system is changed to automatic operation. The gas analyzer 42, such as mass spectrometer, etc., analyzes the sampling from the OG gas 9, to indicate as transmitting N2 concentration to a control device 44. By comparing this indicated valve of N2 concentration with the aimed value of N2 concentration beforehand set, control signal is transmitted to control valve 46 in accordance with the deviation, so as to become to zero for the deviation, and flow rate in the flue is controlled. And, in case of enclosing rather large quantity of air in the furnace by any cause, the control system detects immediately increase of N2 gas to shut the valve 46.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Industrial application field] The present invention relates to recovery control of OG gas in a steelmaking converter.

More specifically, the present invention relates to a method of recovering high-calorie OG gas by controlling the amount of N2, which is one of the typical components of the air mixed in the OG gas, in order to minimize the amount of air mixed into the OG gas.

[Conventional technology]

Conventionally, the pressure directly above the converter was detected and compared with the furnace mouth pressure setting (atmospheric pressure) of a separately installed control device.
The control valve for the flow rate of the OG gas was controlled (opened and closed) so as to reduce this deviation to zero.

FIG. 2 is a system diagram showing a conventional method for controlling the recovery of OG gas from a converter. Figure: 1 is the converter, 2 is the raw material (hot metal and scrap) put into the converter 1, and 3 is the converter.
is the rotating shaft of the converter 1, 4 is the blowing oxygen for oxidizing the carbon in the raw material 2, 5 is the lance that allows this blowing oxygen 4 to reach the raw material 2, and 6 is the hood located directly above the converter 1. part, 7 is the auxiliary raw material to be charged during blowing, 8 is the hopper for auxiliary raw material input, 9 is the OG gas whose components are to be controlled, 10
1 is a skirt provided as a valve device between the converter 1 and the hood section 6, lla and llb are arrows indicating the direction of movement of the skirt 10, 12 is a secondary injection section, 13 is an upper safety valve, and 14 is an arrow of this upper safety valve. Gas analyzer installation location nearby, 15 is the primary dust collector, 16 is the secondary 11m! 18.17 is ejaculation x
m i total, 18 is an induced blower that sucks the OG gas 9;
19 is the installation position of the gas analyzer, 20 is a three-way valve that switches the direction and flow path of the chimney 23 or recovery valve 21, 22 is a gas holder that accommodates the recovered OG gas 9, 24 is a diffused gas, and 41 is a A conduit that introduces the pressure in the hood 6 to the furnace pressure detector 42a, 43 a signal line that sends the output signal of the furnace pressure detector 42a to a control device 44, and 45 a signal line that sends the output of the control device 44 to a control valve 46. Feed, secondary dust collector 16
This is a control line that controls the flow rate of the OG gas 9 inside.

Next, this operation will be explained. The conventional method for controlling the pressure of the OG gas 9 generated from the converter 1 as described above is to detect the pressure inside the hood 6 with the furnace pressure detector 42a, transmit this output signal to the control device 44, and set the pressure in advance. A signal proportional to the deviation is sent to the control valve 46 to control the flow rate of the OG gas 9 and the pressure inside the hood 6.

However, the pressure ζ on the converter 1 changes due to the oxidation reactor in the converter 1 and the metal attached to the furnace mouth, and as described above, in the method using the furnace pressure detector 42a, Since the set value of the mouth pressure cannot be calculated properly (the set value should be changed according to the reaction situation in the furnace, but it is fixed at a constant value), OG gas is removed from between the skirts 10 at the furnace mouth. There were unstable factors such as a decrease in the calorie content of the collected gas due to the dissipation of 9 or the entrainment of air.

[Problem that the invention seeks to solve]

In the conventional converter pressure control method using a furnace pressure detector as described above, it is difficult to follow pressure changes due to reactions inside the converter and metal adhesion at the furnace mouth and obtain ideal control results. Met. Therefore, the O recovered by air entrainment
There have been problems such as the calorie content of the G gas decreasing, or the pressure inside the furnace exceeding atmospheric pressure, causing it to blow out of the converter from the skirt and burn.

[Means for solving problems]

In the converter OG gas recovery control method according to the present invention,
A part of the OG gas from the converter is introduced into a gas analyzer such as a mass spectrometer to measure the N2 concentration in the OG gas, and the exhaust gas is adjusted so that the deviation between this N2 concentration and the target value is zero. It controls the flow rate.

[Operation] In the present invention, a part of the OG gas in the hood is introduced into a mass spectrometer to measure the N2 concentration.

This N2 concentration is transmitted to the control device and compared with the target value of N2 concentration, and a signal proportional to this deviation is sent to the control valve to the secondary ta! ! 11 Controls the flow rate of OG gas flowing inside the vessel.

〔Example〕

FIG. 1 is an explanatory diagram showing an embodiment of the present invention. In the figure, 1 to 24, 41, 43 to 46 have the same structure as the conventional structure shown in FIG. 2, and 42 is a gas analyzer that analyzes the components of the OG gas 9 in the hood 6.

Next, this operation will be explained. If raw materials 2 (molten pig iron and scrap) are put into the converter 1, and the chimney 23 side of the three-way valve 20 is opened and the induced air 1fi18 is started (the control device is stopped and manually controlled), it will be communicated to the converter engineer. The pressure drop occurs in the filtration channel. Here, oxygen 4 is blown through lance 5.
When OG gas 9 is gradually blown in, the carbon in raw material 2 reacts with blowing oxygen 4, and the CO concentration in OG gas 9 becomes 70 to 80%.

When the pressure inside the hood section 6 becomes equal to the initial setting value (approximately atmospheric pressure) and reaches a steady state, the three-way valve 20 closes the recovery valve 21.
Switch to the side and switch the drug control system to automatic operation.

The gas analyzer 42 samples the OG gas 9 through the conduit 41, analyzes it, and transmits the Nz concentration to the control bag g44. If this N2e degree indication value is compared with a preset target value of N2 concentration (1 to 2%) and a control signal corresponding to this deviation is transmitted to the control valve 46 via the control line 45, smoke will be generated. It is possible to control the flow rate within Hokkaido. When the OG gas 9 contains 1 to 2% N2 gas, there is a slight gap between the top of the converter 1 and the skirt 10, indicating that the inside of the furnace is under negative pressure (gauge pressure is negative). It shows.

Now, if we assume that the gas flow rate generated from the furnace has decreased due to some reason, the pressure of the furnace has decreased, and a rather large amount of air has been drawn into the furnace, the control system ζ will immediately detect an increase in N2 gas. From then on, controller 44 operates to close control valve 46. Therefore, it is possible to avoid storing the gas in the gas holder 22, which is a low-calorie gas containing too much air.

If the flow rate of generated gas from inside the furnace increases and the furnace pressure rises,
The control system detects a decrease in the N2 component in the OG gas 9, that is, a decrease in the inflow of air, and opens the control valve 46, operating so that only high-calorie gas is accumulated in the gas holder 22.

When finishing the blowing, use the lance 5 with the blowing oxygen 4 stopped.
, the control system is stopped, and the three-way valve 20 is closed to the chimney 23.
The cycle of switching to the side and taking out the molten steel is repeated.

The above operation analyzes the N2ax in the OG gas 9 using the gas analyzer 4.
This contributes to the quality control of the recovered gas by measuring and controlling it using 2, but the presence of minute amounts of N2 gas means that the pressure inside the hood 6 is slightly lower than atmospheric pressure. Therefore, the same effect as controlling the pressure of the OG gas 9 can be obtained.

In addition, in this example, although the OG gas was controlled by measuring the N4 degree, other gases such as Ar and He, which are proportional to the amount of air mixed in, and which are not generated from the raw materials, may be present. It would also be possible to construct a control system by measuring the active gas concentration.

〔Effect of the invention〕

This invention [As explained above, by measuring the degree of N2C in the OG gas using a gas analyzer (for example, a mass spectrometer), it is possible to detect whether or not air has entered the hood, and the result of this detection is Send it to the control device and compare it with the set value,
A signal corresponding to the deviation resulting from this comparison is sent to the control valve to control the flow rate of the OG gas, which has the effect of preventing a decrease in the calorie content of the OG gas collected in the gas holder.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a conventional method for controlling converter OG gas. In the figure, 1 is the converter, 2 is the raw material (hot metal and scrap), and 4 is the blowing t! R oxygen, 5 is lance, 9 is OG gas, 1
0 is the skirt, 22 is the gas holder, 42 is the gas analyzer, 44 is the control device, and 46 is the control valve. Agent: Masatoshi Sato, Patent Attorney ■ Figure 2

Claims (1)

[Claims] (1) Introduce a part of the OG gas from the converter into a gas analyzer such as a mass spectrometer, measure the N_2 concentration in the OG gas, and set the deviation between this N_2 concentration and the target value to zero. A converter OG gas recovery control method characterized by controlling the exhaust gas flow rate as follows.