JPS6347316A - Smelting, reducing and refining equipment - Google Patents

Abstract

PURPOSE:To adequately control the temp. of the reducing gas entering the prereducing furnace of a molten iron producing apparatus consisting of a smelting and reducing furnace and the prereducing furnace and to stabilize the reducibility of the iron ore in the prereducing furnace at a high value by cooling the exhaust gas of the prereducing furnace and returning the gas to the prereducing furnace. CONSTITUTION:The high-temp. exhaust gas from the smelting and reducing furnace 1 is introduced into the prereducing furnace 2 to prereduce the iron ore in the furnace. The reduced iron ore is supplied to the smelting and reducing furnace. The reducibility of the iron ore in the prereducing furnace 2 is not stable and is low if the temp. of the exhaust gas of the smelting and reducing furnace is too high and fluctuates excessively. The high-temp. exhaust gas from the prereducing furnace 2 is cleaned in a dust collector 5 and is put into a heat recovery device 6 where high-temp. high-pressure steam is generated to lower the gas temp. The low-temp. gas is passed through a flow meter 12, a valve 8, a flow meter 14 and a thermometer 13 and is mixed with the exhaust gas of the smelting and reducing furnace by which the gas is cooled. The data obtd. with the flow meters 12, 14 and the thermometer 13 as well as a thermometer 10 and gas analyzer 11 in the inlet of the prereducing furnace are inputted to an arithmetic unit 15 by which the opening of a valve 8 of the flow passage for the cooled gas is regulated to control the temp. of the gas entering the prereducing furnace to an optimum value.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a melting process in which iron ore is blown into molten pig iron in a smelting furnace together with coal and lime, and oxygen gas is blown into the molten pig iron through a lance and a bottom tuyere. Regarding the reduction refining equipment, in more detail, one of the exhaust gases supplied from the smelting reduction furnace to the preliminary reduction furnace.
This invention relates to smelting reduction refining equipment that can control the degree of oxidation.

[Prior Art] The smelting reduction refining method is an alternative to the blast furnace iron manufacturing method, and in order to eliminate the disadvantages of the blast furnace iron manufacturing method, such as the high equipment cost of the blast furnace and the need for a vast site, It has been developed in recent years. In such a smelting reduction smelting method, pre-reduced ore, powdered coal and lime are injected into the hot metal in the smelting furnace through a tuyere provided at the bottom of the furnace, and oxygen gas is injected through another tuyere. As well as blowing into hot metal,
Oxygen gas is blown onto the hot metal from the top of the furnace through a lance inserted into the furnace. Then, the coal is dissolved in the hot metal, and the ore is reduced by the carbon in the coal. CO gas generated from hot metal is secondary combusted by oxygen gas blown from a lance and becomes CO2 gas. This CO
The sensible heat of the two gases is transferred to the forming slag covering the hot metal, and then returned to the hot metal.

[Problems to be solved by the invention] By the way, the exhaust gas generated in the melting reduction process contains reducing gases such as GO and H2.
It is highly conceivable to use it for preliminary reduction of ores. However, the temperature of this exhaust gas varies in the range of 1500 to 1800° C. due to fluctuations in various conditions during the melting reduction process. For this reason, there is a problem that the reduction rate of the ore varies significantly. Another problem is that the temperature of the exhaust gas is too high, making it impossible to maintain a high reduction rate.

This invention was made in view of such circumstances, and
It is an object of the present invention to provide a smelting reduction refining facility that can preliminarily reduce ore at a high reduction rate and with little variation in reduction rate.

[Means for Solving the Problems] The smelting and refining equipment according to the present invention includes a smelting reduction furnace, a pre-reduction furnace for pre-reducing ore, and a smoke refining furnace for guiding exhaust gas generated from the smelting-reduction furnace to the pre-W4 reduction furnace. a cooling means for cooling the flue gas of the pre-reduction furnace; a supply pipe for supplying the flue gas cooled by the cooling means into the flue; It is characterized by comprising an IIM means for controlling the exhaust gas temperature to a predetermined temperature. In this case, the exhaust gas flowing through the supply pipe has substantially the same composition as the exhaust gas of the preliminary reduction furnace. It is preferable.

[Operation] In this invention, the exhaust gas generated in the smelting reduction furnace is supplied to the pre-reduction furnace through the flue, and the ore is pre-reduced by this exhaust gas. In this case, the exhaust gas from the pre-reduction furnace is cooled by a cooling means, and this gas is passed through the supply pipe and supplied into the flue to cool the exhaust gas in the flue. Furthermore, the control means controls the exhaust gas temperature at the inlet of the preliminary reduction furnace to a predetermined temperature by adjusting the gas flow in the supply pipe. Therefore, the temperature of the exhaust gas supplied to the pre-reduction furnace is lowered and the exhaust gas is maintained at a constant temperature, so that the ore can be pre-reduced at a high reduction rate with little variation in the reduction rate.

[Example 1] FIG. 1 is a schematic diagram showing a smelting reduction refining equipment according to an example of the present invention. In the figure, double lines indicate the flow of exhaust gas, and thin lines indicate the flow of signals. High-temperature exhaust gas generated in the smelting a reduction furnace 1 is sent to the preliminary reduction furnace 2 and used for preliminary reduction of ore. A hood 3 is provided above the smelting a reduction furnace 1, and a flue 4 is connected to the hood 3, so that the hood 3 and the flue 4 guide the exhaust gas to the preliminary reduction furnace 2. It has become. This exhaust gas is used to reduce ore in the pre-reducing furnace 2, then collected in a collector 5, and then supplied to a heat recovery device 6. In this thermal surface containment fi6, the heat of the exhaust gas is recovered as, for example, steam, thereby cooling the exhaust gas. Part of the exhaust gas exiting the heat recovery device 6 is supplied to a gas supply pipe 7 extending to the inside of the flue 4, and the remainder is supplied to a downstream process. The gas flowing through the gas supply pipe 7 has a flow rate of r! 4I and supplied to the inside of the flue 4 to cool the exhaust gas inside the flue 4. Moreover, this gas has substantially the same composition as the exhaust gas generated in the preliminary reduction furnace 2, except that it has been purified.

A thermocouple 9 is installed at the exhaust gas outlet of the melting reduction furnace 1, and the temperature of the exhaust gas in this portion is detected by this thermocouple 9. In addition, at the exhaust gas inlet of the preliminary reduction furnace 2,
and a gas analyzer 11 are installed, and this thermocouple 1
0 and the gas analyzer 11 detect the exhaust gas temperature and exhaust gas composition of this portion, respectively. Furthermore, a heat recovery device 6
A flow meter 12 is installed on the downstream side of the exhaust gas, and this flow meter 12 detects the flow rate of exhaust gas. These thermocouples 9
, 10, gas analyzers 11 and 8! The detection signal detected by the meter 12 is output to the calculation device 15. on the other hand,
A thermometer 13 and a flow meter 14 are installed in the gas supply pipe 7, and the temperature and flow of the gas flowing therethrough are detected by the temperature meter 13 and flow meter 14. The detection signals detected by these thermometer 13 and flowmeter 14 are as follows:
It is output to the arithmetic unit 15. In the computing device 15,
Based on the input data mentioned above, a signal is output to the valve 8 to adjust the opening degree of the valve 8 to adjust the gas flow rate through the gas supply pipe 7 to U! 4, the exhaust gas temperature at the inlet of the preliminary reduction furnace 2 is controlled to an appropriate value for the gas composition.

In the smelting reduction refining equipment configured in this way, the exhaust gas generated in the smelting reduction furnace 1 is transferred to the hood 3 and the flue 4.
is supplied to the pre-reduction furnace 2 through which it is used for pre-reduction of the ore. The exhaust gas generated in this preliminary reduction furnace is collected by a dust collector 5, and then its heat is recovered by a heat recovery device 6 and cooled. A part of the exhaust gas exiting the heat recovery device 6 is supplied into the flue 4 through the gas supply pipe 7, and this gas cools the exhaust gas flowing through the flue 4 to a predetermined temperature of 1100 to 1250°C. do. In this case, the signal of the exhaust gas composition detected by the gas analyzer 11 is transmitted to the computing device 1.
5 to determine the appropriate temperature of the exhaust gas at the inlet of the preliminary reduction furnace 2. Further, the exhaust gas temperature at the outlet of the melting reduction furnace 1 and the exhaust gas temperature at the inlet of the preliminary reduction furnace 2 detected by the thermocouple 9 and the thermocouple 10, respectively, and the flowmeter 1
The flow l of exhaust gas detected in step 2 is output to the computing device 15, and based on these data and the data on the exhaust gas composition described above,
The temperature at which the exhaust gas generated in the smelting reduction furnace 1 drops rapidly in the flue 4 and the exhaust gas at the inlet of the preliminary reduction furnace 2 are at an appropriate mr! l
Calculate the difference between the temperature that decreases in the flue 4 in the case of On the other hand, the supply pipe 7 detected by the thermometer 13 and the flow meter 14
Calculating device 1 detects the detection signals of the degree and flow rate of the gas supplied to
Output to 5.

Based on this data, the data on the temperature difference mentioned above, and the data on the exhaust gas flow rate and composition, the amount of gas i to be supplied to the gas supply pipe 7 is calculated in order to bring the exhaust gas temperature at the inlet of the preliminary reduction furnace 2 to an appropriate value. Based on this value, a signal is output from the calculation device 15 to the valve 8, the opening degree of the valve 8 is adjusted to adjust the gas flow rate, and the exhaust gas temperature at the inlet of the pre-reduction furnace 2 is controlled to an appropriate value.

In this way, a part of the exhaust gas cooled by the heat recovery device 6 after being used for pre-reduction of ore is supplied to the inside of the flue 4 via the gas supply pipe 7, and the exhaust gas generated in the smelting reduction furnace 1 is supplied to the inside of the flue 4 through the gas supply pipe 7. In addition to cooling the exhaust gas, the arithmetic unit 15 adjusts the opening degree of the valve 8 to adjust the gas flow rate and control the exhaust gas temperature at the inlet of the preliminary reduction furnace 2 to an appropriate value, so that there is little variation in the reduction rate. Ore can be preliminarily reduced at a high reduction rate.

In addition, the composition of the gas supplied into the flue 4 is
Since the composition is substantially the same as that of the exhaust gas generated in the exhaust gas, and the composition does not change, the temperature of the exhaust gas can be easily controlled.

[Effect of the invention] According to this invention, the exhaust gas generated in the smelting reduction furnace is used for preliminary reduction of ore in the preliminary reduction furnace, and then cooled by the cooling means, and a part of this cooled gas is transferred to the reduction furnace and the preliminary reduction furnace. In addition to cooling the exhaust gas by supplying it into the flue between the reduction furnace and
Since the control means controls the flow rate of this gas to T14 to control the temperature of the exhaust gas at the inlet of the pre-reduction furnace to a predetermined temperature, there is little variation in the reduction rate (and the ore can be pre-reduced at a high reduction rate).

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a smelting reduction refining facility according to an embodiment of the present invention. 1; Smelting reduction furnace, 2; Pre-reduction furnace, 4: Flue, 6; Heat recovery device, 7; Gas supply pipe, 8: Valve, 15; All fan device

Claims (1)

[Claims] A smelting reduction furnace, a pre-reduction furnace for pre-reducing ore, a flue for guiding exhaust gas generated from the smelting-reduction furnace to the pre-reduction furnace, and a cooling means for cooling the exhaust gas of the pre-reduction furnace. , comprising a supply pipe that supplies the exhaust gas cooled by the cooling means into the flue, and a control means that adjusts the flow rate of the gas in the supply pipe to control the temperature of the exhaust gas at the inlet of the preliminary reduction furnace to a predetermined temperature. Melting reduction refining equipment featuring: (2) The smelting reduction refining equipment according to claim 1, wherein the exhaust gas flowing through the supply pipe has substantially the same composition as the exhaust gas of the preliminary reduction furnace.