JP5540627B2 - Damage prevention method for blast furnace top bottom seal valve packing - Google Patents

Description

  The present invention relates to a method for preventing damage to packing (seal rubber) mounted on a blast furnace top lower seal valve.

  The top of a typical bellless blast furnace is shown in FIG. In the operation of the blast furnace, high pressure operation is performed for the purpose of improving productivity. Therefore, as shown in FIG. 1, the inlet 8 of the furnace top hopper (furnace top bunker) 2 is connected to the furnace top hopper 2 and the atmosphere. An upper seal valve 3 is provided for shutting off the air between the furnace top hopper 2 and a lower seal valve 5 is provided at the discharge port 9 of the furnace top hopper 2 for shutting off between the furnace top hopper 2 and the blast furnace inside 7. It is arranged. The upper seal valve 3 and the lower seal valve 5 are connected to levers 4 and 6 that can be rotated in the directions of arrows a and b, respectively. By rotating the levers 4 and 6, the top hopper 2 The inlet 8 or the outlet 9 can be sealed (closed) or opened.

  When charging raw materials such as ore and coke into the blast furnace, the raw materials are charged into the furnace top hopper 2 by the charging conveyor 1. At this time, the inlet 8 of the furnace top hopper 2 rotates the lever 4 in the direction of arrow a to open the upper seal valve 3, while the discharge port 9 rotates the lever 6 in the direction of arrow b. The lower seal valve 5 is closed. When the introduction of the raw material into the furnace top hopper 2 is completed, the inlet 8 of the furnace top hopper 2 rotates the lever 4 in the direction of arrow b to close the upper seal valve 3. In this way, the furnace top hopper 2 is sealed, and the inside of the furnace top hopper 2 is pressurized until the pressure becomes substantially the same as the furnace top pressure. When pressurization in the furnace top hopper 2 is completed, the lower seal valve 5 of the discharge port 9 is opened, and the raw material is charged into the blast furnace furnace 7. Incidentally, the upper seal valve 3 and the lower seal valve 5 perform the above opening / closing operation about 360 times a day.

  FIG. 2 is a cross-sectional view showing the lower seal valve 5 in a closed state. The lower seal valve 5 includes a disk-shaped valve body 11 that rotates integrally with the lever 6, and an annular valve seat 12 that is fixed to the lower end portion of the furnace top hopper 2. A ring-shaped silicon rubber packing (seal rubber) 13 is attached to the valve body 11. By rotating the lever 6 in the direction of arrow b, the upper surface of the packing 13 is the lower end surface of the valve seat 12. Pressure contacted.

  However, the above-described lower seal valve 5 has the following problems. That is, since the periphery of the lower seal valve 5 is exposed to an atmosphere of in-furnace gas containing about 4% of moisture, condensation occurs on the seal surface (upper surface of the packing 13). Condensation occurs on the seal surface (upper surface of packing 13) in this way because of the temperature of the gas in the furnace near the seal surface (upper surface of packing 13) and the temperature in the top hopper 2 (atmospheric temperature) with the lower seal valve 5 as a boundary. This is because the in-furnace gas in the vicinity of the seal surface (upper surface of the packing 13) is cooled to a dew point (saturated water vapor pressure temperature) or lower due to the temperature difference. Thus, when dew condensation occurs on the seal surface (upper surface of the packing 13), the powder in the charged raw material grows on the dewed portion. As a result, the packing 13 is worn and damaged, resulting in a poor seal, the operation of the blast furnace must be stopped, and the packing 13 must be replaced.

  Therefore, in order to extend the life of the packing 13 and improve the operating rate of the blast furnace and reduce the cost of the packing 13, in Patent Document 1, a steam pipe is provided along the outer surface of the valve seat 12 of the lower seal valve 5. The packing 13 is installed, and the outer surface of the valve seat 12 is heated by flowing saturated water vapor of 100 ° C. or higher through the water vapor pipe, whereby the lower seal valve 5 is pressed against the valve seat 12 when the lower seal valve 5 is closed. Is heated indirectly to prevent the furnace gas in the vicinity of the sealing surface (upper surface of packing 13) from being cooled to a temperature below the dew point (saturated water vapor pressure temperature), and condensation on the sealing surface (upper surface of packing 13). And it prevents the adhesion of raw material powder.

JP 63-128107 A

  However, as described in Patent Document 1, in order to extend the life of the packing 13 of the lower seal valve 5, the packing 13 is heated by heating the outer surface of the valve seat 12 using saturated steam at 100 ° C. or higher. Even when the method of indirectly heating is adopted, the packing 13 may be damaged in a short period of time.

  The present invention has been made in view of the circumstances as described above, and can accurately prevent damage to the packing mounted on the blast furnace top lower seal valve, thereby extending the life of the packing. An object of the present invention is to provide a method for preventing damage to the furnace bottom seal valve packing.

  In order to solve the above-mentioned problems, as described above, when the packing 13 is indirectly heated using saturated steam at 100 ° C. or higher, the present inventors indicate the damaged state of the packing 13 damaged in a short period of time. investigated. As a result, the damage to the packing 13 is not a wear damage due to the adhesion of the raw material powder to the upper surface of the packing 13 as in the prior art, but the silicon rubber packing 13 is exposed to a temperature close to its heat resistance temperature (about 200 ° C.). It was found that this was due to thermal damage. The gas at the center of the furnace top mainly arrives around the packing 13, but conventionally, the temperature of the gas at the center of the furnace top has been considered to be less than 100 ° C. However, it was estimated that due to changes in operating conditions, the temperature of the gas at the center of the furnace top was close to 200 ° C., and therefore the packing 13 was thermally damaged.

  Therefore, in order to prevent wear damage due to adhesion of raw material powder to the upper surface of the packing 13 while preventing such heat damage of the packing 13, the present inventors heat the packing 13 as in the prior art. Instead of increasing the temperature of the packing 13, rather, it was considered necessary to cool the packing 13 so that the temperature of the packing 13 was within a predetermined temperature range. However, since it is difficult to cool the packing 13 directly, the packing 13 is indirectly cooled by cooling the valve seat 12.

  Based on the above concept, the present invention has the following features.

  [1] In a blast furnace top lower seal valve provided with a valve body, a valve seat, and a packing attached to the valve body and pressed against the valve seat, a lower end surface of the valve seat pressed against the packing Cooling the valve seat by supplying room temperature nitrogen gas to a groove provided in the vicinity of the inside prevents the wear temperature due to the adhesion of raw material powder while preventing the packing temperature from being thermally damaged. A method for preventing damage to the seal valve packing at the top of the blast furnace, characterized by controlling the temperature within a possible range.

  [2] The temperature of the valve seat is measured, and when the temperature of the valve seat exceeds a predetermined upper limit temperature, supply of room temperature nitrogen gas to the groove provided in the valve seat is started. Damage to the blast furnace top lower seal valve packing according to [1], wherein supply of nitrogen gas at room temperature to the groove provided in the valve seat is stopped when the temperature falls below a predetermined lower limit temperature. Prevention method.

  [3] In the above [2], the upper limit temperature is a temperature determined based on a heat resistant temperature of the packing, and the lower limit temperature is a temperature determined based on a dew point of the gas in the furnace. The method for preventing damage of the blast furnace top lower seal valve packing as described.

  In the present invention, damage to the packing attached to the blast furnace top lower seal valve can be accurately suppressed, and the life of the packing can be extended. As a result, the replacement frequency of the packing is reduced, and it becomes possible to improve the operating rate of the blast furnace and reduce the cost of the packing.

It is a figure which shows the furnace top part of a bell-less type blast furnace. It is sectional drawing which shows a blast furnace top lower seal valve. It is sectional drawing which shows one Embodiment of this invention. It is a figure which shows an example of the temperature transition of the valve seat in one Embodiment of this invention.

  An embodiment of the present invention will be described with reference to the drawings.

  In the embodiment of the present invention, the target is the lower seal valve 5 disposed as a block between the top hopper 2 and the blast furnace 7 shown in FIG. The lower seal valve 5 includes a disc-shaped valve body 11 that rotates integrally with the lever 6 and an annular valve that is fixed to the lower end portion of the furnace top hopper 2 as shown in a sectional view in FIG. And a seat 12. A ring-shaped silicon rubber packing (seal rubber) 13 is attached to the valve body 11. By rotating the lever 6 in the direction of arrow b, the upper surface of the packing 13 is the lower end surface of the valve seat 12. Pressure contacted.

  In addition, in this embodiment, as shown in a cross-sectional view in FIG. 3, a groove 21 penetrating in the circumferential direction is provided in the vicinity of the lower end surface in pressure contact with the packing 13 of the annular valve seat 12. The normal temperature nitrogen gas is supplied into the valve 21 to cool the valve seat 12, thereby indirectly cooling the packing 13 pressed against the valve seat 12, and the temperature of the packing 13 is thermally damaged. The temperature is controlled to be within a temperature range (for example, 100 ° C. to 120 ° C.) in which wear damage due to adhesion of raw material powder can be prevented. In FIG. 3, 21 a is a nitrogen gas supply port to the groove 21, and 21 b is a nitrogen gas discharge port from the groove 21.

  At that time, since it is difficult to directly measure the temperature of the packing 13, a thermometer 22 is installed on the valve seat 12 that is assumed to be substantially the same temperature as the packing 13, and the thermometer 22 The temperature of the packing 13 is indirectly measured by measuring the temperature.

  Then, when the temperature of the valve seat 12 measured by the thermometer 22 exceeds a predetermined upper limit temperature, the supply of room temperature nitrogen gas to the groove 21 of the valve seat 12 is started, and the temperature of the valve seat 12 reaches a predetermined lower limit temperature. If the value is less than the value, the supply of nitrogen gas at room temperature to the groove 21 of the valve seat 12 is stopped.

  Incidentally, the upper limit temperature is a temperature determined based on the heat-resistant temperature (about 200 ° C.) of the packing 13, and is set to 120 ° C. here. The lower limit temperature is a temperature determined based on the dew point of the gas in the furnace, and is set to 100 ° C. here.

  FIG. 4 shows an example in which the temperature of the valve seat 12 is controlled in this way (indirectly, the temperature of the packing 13 is controlled).

  As described above, in this embodiment, the thermal damage and wear damage of the packing 13 attached to the valve body 11 of the lower seal valve 5 can be accurately suppressed to extend the life of the packing 13. it can. As a result, the replacement frequency of the packing 13 is reduced, and it becomes possible to improve the operating rate of the blast furnace and reduce the cost of the packing 13.

  As an example of the present invention, damage to the packing 13 of the lower seal valve 5 was prevented by the above-described embodiment of the present invention (cooling of the valve seat 12 using nitrogen gas). On the other hand, as a conventional example, damage to the packing 13 of the lower seal valve 5 was prevented by the technique described in Patent Document 1 (heating of the valve seat 12 using saturated steam).

  And when the frequency | count of use of the lower seal valve 5 became 35000 times (about 100 days), the state of the packing 13 in this invention example and a prior art example was compared.

  As a result, in the conventional example, a large crack was generated in the packing 13 due to thermal damage, and the sealing performance was greatly deteriorated, whereas in the example of the present invention, thermal damage and wear damage were almost generated in the packing 13. The sealing performance was sufficient.

  In this way, the effectiveness of the present invention could be confirmed.

1 Raw material charging conveyor 2 Furnace top hopper (furnace top bunker)
3 Upper Seal Valve 4 Lever 5 Lower Seal Valve 6 Lever 7 Inside the Blast Furnace Furnace 8 Furnace Top Hopper Charge 9 Furnace Top Hopper Drain 11 Valve Body 12 Valve Seat 13 Packing (Seal Rubber)
21 Groove 21a Supply port to the groove 21b Discharge port from the groove 22 Thermometer

Claims (3)

In a blast furnace top lower seal valve comprising a valve body, a valve seat, and a packing that is attached to the valve body and pressed against the valve seat, the interior of the valve seat in the vicinity of the lower end surface that is pressed against the packing In addition, by cooling the valve seat by supplying room temperature nitrogen gas to a groove that is provided apart from the packing and penetrates in the circumferential direction, the temperature of the packing is reduced while preventing thermal damage to the packing. A method for preventing damage to a blast furnace top lower seal valve packing, wherein the temperature is controlled within a temperature range in which wear damage due to adhesion of the blast furnace can be prevented. In a blast furnace top lower seal valve comprising a valve body, a valve seat, and a packing that is attached to the valve body and pressed against the valve seat, the interior of the valve seat in the vicinity of the lower end surface that is pressed against the packing By cooling the valve seat by supplying normal temperature nitrogen gas to the groove provided in the temperature range of the packing, it is possible to prevent wear damage due to adhesion of raw material powder while preventing thermal damage of the packing Control to
When the temperature of the valve seat is measured and the temperature of the valve seat exceeds a predetermined upper limit temperature, supply of room temperature nitrogen gas to the groove provided in the valve seat is started, and the temperature of the valve seat is predetermined. A method for preventing damage to the blast furnace top bottom seal valve packing, characterized in that the supply of nitrogen gas at room temperature to the groove provided in the valve seat is stopped when the lower limit temperature is exceeded.   The blast furnace furnace according to claim 2, wherein the upper limit temperature is a temperature determined based on a heat-resistant temperature of the packing, and the lower limit temperature is a temperature determined based on a dew point of the gas in the furnace. How to prevent damage to the top seal valve packing.

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