JPS58123838A - Controlling method holding furnace - Google Patents

Abstract

PURPOSE:To accurately control a holding furnace just behind a firing furnace by regulating the internal pressure of the holding furnace to a specified value by feeding air into the furnace so as to prevent flames from flowing into the holding furnace. CONSTITUTION:The internal pressure of a holding furnace 5 just behind a firing furnace 4 is kept under 0.2-0.5mm.Hg by feeding air into the furnace 5 by means of heat holding burners 10 by which combustion is not carried out. Accordingly, flames 90 are prevented from flowing into the furnace 5, and the consumption of fuel in a DL sintering machine can be reduced considerably without deteriorating the quality of sintered ore even if the furnace 5 is used in a complex state.

Description

[Detailed description of the invention] It is related to.

As is well known, in a DL sintering machine, pallets are arranged in a chain shape at the end of the shaft, sintering raw materials are charged into the pallets, and the surface layer of the sintering raw materials is ignited in an ignition furnace. . The ignited sintering raw material is sequentially fired as the pallet advances, and sintering of all layers is completed while reaching the discharge section, where it is discharged to subsequent equipment.

By the way, in a DL sintering machine, a heat retention furnace is generally installed next to the ignition furnace, and the structure is such that the surface layer of the sintered raw material immediately after the ignition is not rapidly cooled. On the other hand, in recent years, there has been a high demand for energy saving, and improvements have been made to increase the layer thickness of the sintering raw material by increasing the sintering capacity and strengthening the granulation of the raw material by adding quicklime to equal pressure. It has become common practice. Furthermore, combustion control in ignition furnaces and heat retention furnaces has become more severe, and various proposals have been made for this purpose.

As a result of repeated various experimental studies on efficient combustion control of ignition furnaces and heat retention furnaces, and in particular on heat retention furnaces, the present inventors have found that combustion control in ignition furnaces and the internal pressure of the furnace can be appropriately controlled. Therefore, depending on the pallet speed, the type of sintering raw materials, the blending ratio, etc., there is little effect on the quality of the sintered ore, even if combustion is not performed in the heat retention furnace, that is, the heat retention furnace is operated in a state where the fire is extinguished. We have obtained knowledge that there is no effect.

The present invention was created as a result of further research based on the above findings, and relates to a method for controlling a heat retention furnace that operates in the above-mentioned digestion state.

Hereinafter, the present invention will be explained in detail based on Examples.

FIG. 1 is a structural diagram of a well-known general L sintering machine. In the figure, the pallets IK are arranged in an expanded endless chain, and the sintering raw material 3 is charged into the pallets IK at the ore feeding section 2. 4 is an ignition furnace, and 5 is a heat retention furnace following the ignition furnace 4. The sintered raw material 3 whose surface layer is ignited in the ignition furnace 4 is successively fired from above to below by the air sucked in by the wind box 6 as the pallet 1 advances, and becomes sintered ore 7, which is discharged. It is discharged to subsequent equipment from s8. Now, the ignition furnace 4 has an ignition burner 9 as shown in the partial sectional view of FIG.
A predetermined number of ignition burners 9 are installed, and the combustion rate of each ignition burner 9 is set according to the type of gas or liquid used for combustion, the speed of the pallet 1, the thickness of the 30 layers of sintered raw material, etc., and is controlled by appropriate means. has been done.

Further, the internal pressure of the ignition furnace 4 is also controlled to a predetermined pressure by controlling the amount of suction air with a nine-curve amount adjustment valve 10 provided at the lower part of the wind box 6. In the experience of the present inventors, when the internal pressure of the ignition furnace is controlled within the range of 0 to -1■Al, the ignition flame 90 ejected from the ignition burner 9 spreads evenly within the ignition furnace 4, resulting in extremely low combustion. It was confirmed that efficient ignition could be achieved depending on the amount. However, as shown in FIG. 2, when the heat retention furnace 5 is operated without burning the heat retention burner 11, the ignition flame 90 flows into the heat retention furnace 5 even if the internal pressure of the ignition furnace is controlled within the pressure range. The inventors' experiments have revealed that a situation occurs in which the combustion efficiency in the ignition furnace 4 is significantly reduced. That is, in the ignition furnace 4, as described above, control is performed to perform efficient ignition with the minimum amount of combustion, and when the ignition flame 90 flows into the heat retention furnace 5, the amount is small. Even so, the impact on combustion efficiency, quality, etc. will be extremely large. As a result of investigating the flow-in phenomenon of the ignition frame 90, the following factors were found. In other words, the wind box 6 is arranged in the lower part of the heat retention furnace 5, and
The air above the pare, -string, and seat 1 in the heat retention furnace 5 is also sucked into the wind box 6. Therefore 79
The amount of air sucked into the wind box 6 is larger than the amount of air that is supplied into the heat retention furnace 5 when the upper part of the rut 1 is covered with the heat retention furnace 5 and the heat retention burner 11 is not burned. , the pressure inside the heat retention furnace 5 becomes significantly lower (11) than the pressure inside the ignition furnace 4, and as a result, the ignition flame 90 flows into the heat retention furnace 5. On the other hand, the heat retention furnace 5 may not retain heat depending on the operating conditions as described above. Since it is necessary to carry out combustion in the burner 12, there is a problem in completely removing the heat retention furnace 5.

The present invention provides a method of controlling a heat retention furnace that enables a drastic solution to the problem of inter-injection points by changing the operation mode of the heat retention furnace. FIG. 3 is a partial sectional view for explaining an example of the control method of the present invention.

That is, in FIG. 3, the heat retention burner 11 that does not perform combustion
is used to supply air into the heat retention furnace 5,
By supplying the air, the temperature inside the heat retention furnace 5 is α2~-0.5-
A-Kept in range. In other words, heat retention burner 11La
Normally, the fuel supply system 12 and the combustion air supply system 13 are connected, and in this embodiment, the on-off valve 141.1 of the fuel supply system 12 is connected.
4 b and 14 c are fully closed, and only the combustion air supply system 130 on-off valves I S m, 15 b, and 15 c are opened. Air is fed into the heat retention furnace 5 from K. A pressure detection end 16 is installed in the heat retention furnace 5, and based on the detected value of the pressure detection end 16, the opening/closing valve 15m is controlled by, for example, a control device 17.

15b, 15cTh! and ML amount adjustment valve 10m, 10b,
The internal pressure of the heat retention furnace is controlled to be maintained within the pressure range by adjusting the opening degree of lQc/), the rotational speed of the blower ν blower 18, the opening degree of an outlet damper (not shown), etc.

The reason for setting the heat retention furnace internal pressure to α2~-〇, 5 ■All K is that when the heat retention furnace internal pressure is higher than 0.2wIkl, the heat retention furnace internal pressure is higher than the ignition furnace internal pressure, and the cold air inside the heat retention furnace is In order to maintain the internal pressure of the heat retention furnace while entering the ignition furnace 4, a large amount of air is required to be supplied, and the power consumption of the blower blower 18 is 4 large, and conversely, the internal pressure of the heat retention furnace is -0.5 wm. Based on the results of various experiments, it has been confirmed that when the temperature is lower than Ali, the ignition angle of 9° flows into the heat retention furnace 5, reducing the combustion efficiency in the ignition furnace 4 and deteriorating the quality of the sintered ore. It is something.

Next, an example in which the present invention was implemented in an actual operation will be described. DL sintering M K with sintering area of 170-
vs Teno” speed f 2.05 m/m,
B Under the operating conditions of 4,700 tons of production, the combustion air (1) shown in FIG.
By supplying air at a rate of 000 to 10,00 Nm'/H and varying the internal pressure of the heat retention furnace, we investigated the associated changes in temperature within the ignition furnace, fluctuations in fuel consumption, and quality of sintered ore. . FIG. 4 is a diagram showing one implementation result of the transition state of the temperature in the ignition furnace corresponding to the change trap in the internal pressure of the heat retention furnace. As can be seen from Fig. 4, even if the amount of combustion gas burned in the ignition furnace is the same, as the internal pressure of the heat retention furnace approaches rQJ, the temperature inside the ignition furnace increases gradually (1 degree Celsius) and reaches the maximum at "0". Confirmed 6 In this example, when the internal pressure of the heat retention furnace is maintained at rOJK, there is no flow of cold air into the ignition furnace and no flow of the ignition frame 9o into the heat retention furnace, and the temperature inside the ignition furnace is lower than that of the conventional heat retention furnace. 1080℃ to 1170℃ under operation without feeding
The temperature rose sharply to ℃. When the internal pressure of the heat retention furnace increases or decreases (rQJ), the above-mentioned ignition 7 frame 90 and the inflow of cold air occur, and the temperature within the ignition furnace gradually decreases, but within the range of 01-Q, 5 ■. It is possible to maintain a high temperature of 1150 degrees Celsius or higher within the temperature range. Especially 0±α2■
Within the range of person t, it costs almost no more than rQJ.
It has been confirmed that it is effective in ensuring a temperature of 160°C or higher, and the internal pressure of the heat retention furnace can be controlled to be higher than "0", that is, to the positive side, as described above, as long as it is within the range of 0 to α5 ■Ay. The influence line on the temperature inside the ignition furnace is not a problem, but since the amount of air required to maintain it is extremely large, in the present invention, the quality of the sintered ore was investigated to control it to the positive side. It is a diagram showing the results, and shows the quality of sintered ore in terms of drop strength index (SI). As can be seen from Fig. 5, there is no difference in the quality of the sintered ore even when the heat retention furnace is operated with the fire extinguished.Compared to this, the basic unit of coke oven gas used in the ignition burner 9 is 2.6 Nd/ton. It became possible to reduce the width to -. Incidentally, the force Q in the fuel consumption rate is 4030Ktd/N-.

As described above, the present invention achieves multiple heat retention by supplying air into the heat retention furnace, maintaining the internal pressure of the heat retention furnace at a predetermined pressure, and preventing the ignition frame 9o from flowing into the heat retention furnace 5. The furnace 5 is also used without degrading the quality of the sintered ore (DL
This is a turtle that has made it possible to drastically reduce the fuel consumption in sintering machines.

On the other hand, the means for supplying air into the heat retention furnace 5 is not limited to the one described in the above embodiment, but may be any means that can be opened and closed to the heat retention furnace 5 as long as it can maintain the internal pressure of the heat retention furnace at a predetermined pressure. Attach the door”−
It is also possible to adopt a method of sucking and supplying air from outside the furnace by opening the shell door and communicating the inside of the heat retention furnace with the outside of the furnace. However, in the experience of the present inventors, the feeding means shown in FIG. 3 has been found to be effective as it allows easy control of frying with high accuracy.

As described above, although the present invention has a simple structure and Fi, its practical effects are very large.

[Brief explanation of the drawing]

Fig. 1 is a structural diagram of a well-known general L sintering machine, Fig. 2 is a partial sectional view for explaining the flow of the ignition frame,
FIG. 3 is a sectional view of an ignition furnace and a heat retention furnace showing one embodiment of the control means for a heat retention furnace based on the present invention, and FIGS. 4 and 5 are diagrams showing an example of the effects of the present invention. The figure is a diagram showing the change in the temperature inside the ignition furnace in response to changes in the internal pressure of the heat retention furnace.
Figure 5 shows the internal pressure of the heat retention furnace! FIG. 2 is a diagram showing changes in the quality of sintered ore and the fuel consumption rate in response to changes in the fuel efficiency. 1: Pallet, 2: Ore feeding section, 3: Sintering raw material. 10c: Air volume adjustment valve, 11: Heat retention burner, 12: Fuel supply system, 13: Combustion air supply system, 14m, 14b14c
: Open/close valve % 15a, 15b, 15c: Open/close valve, valve: Pressure detection end, 17: Control amount, 18: Air blower Agent: Patent attorney Masamitsu Akizawa and 2 others i: i'b 1978
Commissioner of the Japan Patent Office February 23, 2016 Case Indication Special No. 1 Sho 57-5841; 3 Relationship with the person making the amendment Applicant IE Place of residence (residence) 6%, 2-chome Otemachi, Chiyoda-ku, Tokyo No.3 Name (Name) (665) Nippon Steel Corporation-41“6
Date: Showa, month, day (shipment) + Notice of reasons for refusal 6 Number of inventions increased by amendment None 1 ・:: Contents of amendment 1, 2nd line from the bottom of page 2 of the specification “In the above-mentioned digested state” is changed to "in the extinguished state." 2, r1 year old, page 8, line 11 “Raw material consumption unit” is changed to “Fuel consumption consumption”
I'll change it to. 3. Revise drawing f4 as shown in the attached sheet. Juice 4 - Lee Min f! -Jotodoori & (, mt \ Hinoki)

Claims (1)

[Claims] (1) Air is supplied into the heat retention furnace following the ignition furnace to maintain the heat retention furnace internal pressure at 0.2 to -0.5 m A4.
A method for controlling a heat retention furnace in a DL sintering machine, characterized by preventing an ignition flame from flowing into the heat retention furnace.