JP5194504B2 - Apparatus for injecting gas reducing material into blast furnace and operating method of blast furnace using the same - Google Patents

Description

  The present invention relates to a device for blowing a gas reducing material into a blast furnace, and in particular, when both a solid reducing material (pulverized coal, used plastic, etc.) and a gas reducing material (city gas, etc.) are blown into the furnace from a blast furnace tuyere. The present invention relates to an apparatus for injecting a gas reducing material into a blast furnace used for the blast furnace and a method for operating the blast furnace using the apparatus.

In a blast furnace, as a means for achieving a high output ratio and a low reducing material operation, a gas reducing material (reducing gas) such as natural gas or city gas is blown from the tuyere. However, for example, when blowing this gas reducing material in a large blast furnace of 5000 m ³ class, a tuyere blowing pressure of 400 Kpa or more, and around 40 tuyere, hot air is blown around the blast furnace from the hot air main. When using a hot air blowing device that is sent to a pipe and then supplied to a blowing nozzle provided at each tuyere, the large blast furnace has a large number of tuyere, so that the amount of gas blown into each tuyere is uniform. In order to prevent backfire, it is necessary to secure a certain blowing speed.However, as the blast furnace becomes larger, the pressure inside the furnace becomes larger, especially when the amount of blown gas decreases. It was difficult to ensure the blowing speed, and there was a problem that the blowing of the gas reducing material was not easy. As an apparatus for solving such a problem, a plurality of ring-shaped reducing gas supply pipes arranged on the outer periphery of the furnace body of the blast furnace, a plurality of tuyere arranged circumferentially on the outer wall of the furnace body, 2. Description of the Related Art A reducing gas blowing device for a blast furnace is known that includes a reducing gas blowing tube connected to a plurality of tuyere from a ring-shaped reducing gas supply tube (see, for example, Patent Document 1). Control of the amount of reducing gas (gas reductant) injected into each tuyere is installed in the original pipe of each ring pipe because the equipment cost is high and the control is complicated if a flow control device is individually installed for each tuyere. It is carried out at once with the flow control valve.
JP 2006-206994 A

  By using the reducing gas blowing device to the blast furnace described in Patent Document 1, even in a large blast furnace, the gas reducing material can be easily and stably blown in a balanced manner, and the amount of blowing is adjusted. You can also.

  On the other hand, in normal blast furnace operation, tuyeres such as pulverized coal are injected. When performing operations in which both solid reducing material (pulverized coal, used plastic, etc.) and gas reducing material are blown from the tuyere, usually one lance for blowing solid reducing material and one for gas reducing material. Although it is installed at each tuyere, the lance for blowing the solid reducing material is powder blowing, and therefore it may be necessary to stop the blowing due to blockage of the tip of the lance or the like.

  At tuyere where pulverized coal can no longer be blown, the theoretical combustion temperature at the tuyere's tip increases by 200-300 ° C over other tuyere and promotes the deterioration of coke in the blast furnace due to thermal shock. Deteriorating.

  In order to avoid the deterioration of the furnace condition, the lance replacement work for the tuyere where pulverized coal can no longer be blown is performed. ~ 3000t).

  Therefore, the object of the present invention is to solve such a problem of the prior art and stop the blowing of the blowing lance of the solid reducing material when performing the blast furnace operation in which both the solid reducing material and the gaseous reducing material are blown from the tuyere. In this case, it is to provide a gas reducing material injection device to the blast furnace that can continue the operation of the blast furnace without deteriorating the blast furnace condition, and a blast furnace operating method using the same. .

The features of the present invention for solving such problems are as follows.
(1) A gas reducing material blowing device that is installed and used in a blast furnace in which a solid reducing material and a gas reducing material are blown into a furnace from a tuyere, and is disposed on the outer periphery of the furnace body of the blast furnace A plurality of ring-shaped gas reducing material supply pipes, a gas reducing material blowing pipe connecting the ring-shaped gas reducing material supply pipe and a gas reducing material blowing lance installed in the tuyere, and the ring-shaped gas A gas reducing material supply main for supplying the gas reducing material to the reducing material supply pipe, and a gas reducing material supply for supplying the gas reducing material to each of the ring-shaped gas reducing material supply pipes by branching from the gas reducing material supply main A ring-shaped gas reducing material supply pipe dedicated to when the solid reducing material blowing is stopped, and a ring-shaped gas reducing material supply pipe dedicated to when the solid reducing material blowing is stopped. And solid reduction connecting the gas reducing material blowing lance A blast furnace consisting of a dedicated gas reducing material blowing pipe when the blowing is stopped and a dedicated reducing gas supply pipe when the solid reducing material blowing is stopped for supplying the gaseous reducing material to the ring-shaped gas reducing material supply pipe when the solid reducing material is stopped. Gas reducing material blowing device.
(2) When using the apparatus described in (1) and stopping the blowing of the solid reducing material from the tuyere in the blast furnace in which the solid reducing material and the gaseous reducing material are blown into the furnace from the tuyere In addition, the supply of the gas reducing material from the ring-shaped gas reducing material supply pipe to the lance for blowing the gas reducing material at the tuyere is stopped, and the gas reduction is performed from the dedicated ring-shaped gas reducing material supply pipe when the solid reducing material blowing is stopped. Blast furnace operation method for supplying gas reducing material to lance for blowing material.
(3) From the flow rate of the gas reducing material supplied from the ring-shaped gas reducing material supply pipe before stopping the blowing of the solid reducing material, the gas reducing material is supplied from the ring-shaped gas reducing material supply pipe at the time of stopping the solid reducing material blowing. The blast furnace operating method according to (2), wherein the flow rate of the gas reducing material supplied to the blowing lance is increased.

  According to the present invention, it becomes possible to individually control the flow rate of the gas reducing material to the tuyere where the solid reducing material cannot be blown, and thereby the theoretical combustion temperature at the tip of the tuyere Can be kept constant, so that blast furnace conditions can be prevented from deteriorating. Further, every time the lance for injecting the solid reducing material is closed, it is not necessary to stop the operation of the blast furnace for the lance replacement work, so that the productivity of the blast furnace is increased.

  When performing the blast furnace operation in which both the solid reducing material and the gas reducing material are blown from the tuyere, the present inventors, when stopping the blowing of the solid reducing material at a certain tuyere, the theory at the tip of the tuyere In order to make the combustion temperature the same level as other tuyere, we thought that it was possible to cope by increasing the flow rate of the gas reducing material. In this case, the flow rate of the gas reducing material is required to be about twice the normal flow rate.

  Note that when the blowing of the solid reducing material is stopped, a predetermined amount of the solid reducing material can be blown when the lance for blowing the solid reducing material is blocked or when the lance tip is not closed. When it disappears, the case where it becomes impossible to blow a solid reducing material by the equipment trouble of piping, etc. are mentioned.

  Hereinafter, as a typical example of the solid reducing material blowing stop, a case where the solid reducing material blowing lance is blocked will be described as one embodiment.

  2 and 3 show a reducing gas (gas reducing material) blowing device described in Patent Document 1 which is a conventional technique. FIG. 2 shows a reducing gas blowing device, and FIG. 3 shows a state where the device of FIG. 2 is attached to a blast furnace. 2 and 3, the reducing gas is blown into the blast furnace from the four ring pipes through the blow pipes. Control of the amount of reducing gas injected is carried out in a lump using flow control valves installed in the original pipe of each ring pipe. For example, in a blast furnace with 38 tuyere, the flow rate of 9 to 10 tuyere is collectively adjusted with one flow control valve. Therefore, when the apparatus shown in FIGS. 2 and 3 is used, it is impossible to increase only the gas flow rate at the tuyere where the solid reducing material cannot be blown. The solid reducing material is blown into the blast furnace together with the carrier gas from a solid reducing material blowing lance installed in the tuyere through a different path from the gas reducing material.

  In order to make it possible to adjust the gas flow rate of the gas reducing material for each tuyere, a single pipe is installed for each tuyere and the same number of flow control valves and flow meters as the number of tuyere are installed. Although it is possible, the equipment cost becomes high and the control becomes complicated. There is a means to install a flow control valve and a flow meter in the blowing pipe, but there are cases where it cannot be installed due to the arrangement in the actual equipment, and there is a flow control valve around the tuyere of high temperature, dust and gas atmosphere. Since a flow meter will be installed, there is a problem not only in equipment cost but also in durability.

  Therefore, the present inventors have provided a ring-shaped gas reducing material supply pipe and a flow rate dedicated to a tuyere for when the solid reducing material cannot be blown and the gas reducing material is blown about twice as much as usual. The present invention has been completed by finding that an installation capable of adjusting the gas flow rate of the individual tuyere can be made by installing a dedicated line for stopping the blowing of the solid reducing material consisting of a flow control valve. When using the dedicated line at the time of stopping the solid reducing material blowing, close the blowing pipe normally used by the valve installed around the tuyere and supply the gaseous reducing material only from the dedicated line side when stopping the solid reducing material blowing To do. The amount of gas reductant supplied to the tuyere where the solid reductant can no longer be blown is about twice that of a normal tuyere and does not differ between tuyere. Corresponding to the case where there are several, the gas reducing material can be supplied simultaneously.

  The gas reducing material used in the present invention is a reducing gas, such as methane, propane, city gas, natural gas, and gas such as by-product gas in a steelworks generated from a blast furnace, coke, converter, etc. . Moreover, the solid reducing material used in the present invention is a solid carbon-containing substance such as pulverized coal or waste plastic as described above.

  The present invention will be described in detail with reference to FIG. FIG. 1 is a schematic view of an embodiment of the apparatus for injecting a gas reducing material into a blast furnace according to the present invention. The gas reducing material blowing device 1 includes a plurality of (in the present embodiment, four) ring-shaped gas reducing material supply pipes 2a to 2d and a gas reducing material blowing apparatus installed in the tuyere from the ring-shaped gas reducing material supply pipe 2. Branching from the gas reducing material blowing pipe 4 connected to the lance 3, the gas reducing material supply main pipe 5a for supplying the gas reducing material to the ring-shaped gas reducing material supply pipe 2, and the gas reducing material supply main pipe 5a. Gas reducing material supply pipes 5b to 5e for supplying gas to each ring-shaped gas reducing material supply pipe 2, and further, a ring-shaped gas reducing material supply pipe 6 dedicated to when the solid reducing material blowing is stopped and a solid reducing material blowing dedicated to stopping. A solid reducing material blowing pipe 7 that is connected to the lance 3 for blowing the gas reducing material from the ring-shaped gas reducing material supply pipe 6 and a dedicated ring-shaped gas reducing material supply pipe 6 that is used when the solid reducing material blowing is stopped. Gas reducing material The gas reducing material supply pipe 8 includes a gas reducing material supply main pipe 5a and a gas reducing material supply pipe 8 used when the solid reducing material blowing is stopped. And the valve 10. 11 is a valve, 12 is a check valve, and 13 is a flexible hose. In FIG. 1, only one gas reducing material blowing lance 3 is shown, but there are actually lances of the number of tuyere, and each of them has gas in any of the ring-shaped gas reducing material supply pipes 2 a to 2 d. It is connected via the reducing material blowing pipe 4 and to the ring-shaped gas reducing material supply pipe 6 dedicated to when the solid reducing material blowing is stopped via the dedicated gas reducing material blowing pipe 7 when the solid reducing material blowing is stopped. . The tuyere on which the lance 3 for blowing the gas reducing material is installed is arranged in an equal number with respect to each of the ring-shaped gas reducing material supply pipes 2a to 2d so as to be substantially equally spaced.

  A plurality of ring-shaped gas reducing material supply pipes and a ring-shaped gas reducing material supply pipe dedicated to stopping the solid reducing material blowing are arranged on the outer periphery of the furnace body of the blast furnace. In FIG. 1, the diameter of the dedicated ring-shaped gas reducing material supply pipe 6 when the solid reducing material blowing is stopped is shown to be larger than the diameter of the ring-shaped gas reducing material supply pipes 2 a to 2 d. Can be arranged at different height positions in the blast furnace.

  Using the apparatus of FIG. 1, 38 tuyere are arranged on the outer wall of the blast furnace body, and each tuyere is used for blowing pulverized coal as a solid reducing material and for blowing city gas as a gas reducing material. One lance is installed at each time, and it is used to inject solid reductant when pulverized coal ratio (PCR) 80kg / molten metal t and city gas (LNG) ratio 30kg / molten metal t The operation method when the lance is blocked will be described.

  In order to make the theoretical combustion temperature at the tip of the tuyere where the lance for blowing the solid reducing material closes the same level as the other tuyere, the flow rate of the gas reducing material is set to about twice the normal flow rate. First, the manual ball valve 11a is closed, and the blowing of city gas from the normal line is stopped. At the same time, the manual ball valve 11b is opened, the dedicated gas reducing material supply pipe 8 when the solid reducing material blowing is stopped, the dedicated ring-shaped gas reducing material supply pipe 6 when the solid reducing material blowing is stopped, and the dedicated gas reducing material blowing when the solid reducing material blowing is stopped. The city gas is supplied to the gas reducing material blowing lance 3 through the pipe 7. At this time, the flow control valve 10 is adjusted to perform blowing at a city gas ratio (LNG) of about 60 kg / molten metal t. This prevents the tuyere tip temperature from increasing when the lance is blocked, and stable operation can be continued.

  The facility of the present invention can cope with the occurrence of a plurality of tuyere with a solid reducing material blowing lance blocked. However, when the lance is blocked in more than four places, the operation of the blast furnace is stopped. It is desirable to replace the lance. If the lance blockage is within 4 locations, the amount of air blown from the dedicated ring-shaped gas reducing material supply pipe when the solid reducing material blowing is stopped to the dedicated gas reducing material blowing pipe when the solid reducing material blowing is stopped is between each tuyere. There is little fluctuation, and well-balanced blowing can be performed.

In a large blast furnace with a volume of about 5000 m ³ and a number of tuyere of 38, operation was performed in which pulverized coal (PC) and city gas (LNG) were blown from the tuyere. The city gas components were CH ₄ : 88.0%, C ₂ H ₆ : 5.8%, C ₃ H ₈ : 4.5%, C ₄ H ₈ : 1.7%, and the gas specific gravity was 0.837 kg / Nm ³ .

The operating conditions of the base were as follows: air volume: 7600 Nm ³ / min, oxygen flow rate: 44000 Nm ³ / H, pulverized coal ratio: 80 kg / molten iron t, LNG ratio: 30 kg / molten iron t per tuyere. The flow rate of the blown gas from the LNG blowing lance was 500 Nm ³ / H, and the flow rate was 97.2 m / s.

During operation, one of the lances for injecting pulverized coal became clogged. The operating conditions in this case were: blast volume: 7600 Nm ³ / min, oxygen flow rate: 44000 Nm ³ / H, pulverized coal ratio: 0 kg / molten metal t, LNG ratio: 30 kg / molten metal t. The theoretical combustion temperature at the tuyere tip of the tuyere clogged with lances increased by about 200 ° C compared to about 2300 ° C under the base operating conditions, which promoted deterioration of coke in the blast furnace due to thermal shock and deteriorated blast furnace conditions As a result, a temporary breeze was performed to replace the lance. This resulted in a reduction of about 2000 tons.

Next, when clogging occurred in one of the pulverized coal blowing lances during operation, the amount of LNG blown was doubled using the gas reducing material blowing device of the present invention. The operating conditions are blast volume: 7600 Nm ³ / min, oxygen flow rate: 44000 Nm ³ / H, pulverized coal ratio: 0 kg / molten metal t, LNG ratio: 60 kg / molten metal t, flow rate of blown gas from LNG blowing lance Was 1000 Nm ³ / H, and the flow rate was 194.3 m / s. The theoretical combustion temperature at the tuyere tip of the pulverized coal clogged tuyere was kept constant at 2300 ° C, thereby preventing the blast furnace from deteriorating. There was no need for a temporary wind break to replace the lance.

The schematic of one Embodiment of the gas reducing material injection apparatus to the blast furnace of this invention. Schematic of reducing gas blowing device (prior art). FIG. 3 is a schematic view of a state in which the apparatus of FIG. 2 is attached to a blast furnace (prior art).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas reducing material blowing apparatus 2 (2a-2d) Ring-shaped gas reducing material supply pipe 3 Gas reducing material blowing lance 4 Gas reducing material blowing pipe 5a Gas reducing material supply main pipe 5b-5e Gas reducing material supply pipe 6 Dedicated ring-shaped gas reducing material supply pipe when solid reducing material blowing is stopped 7 Dedicated gas reducing material blowing pipe when solid reducing material blowing is stopped 8 Dedicated gas reducing material supply pipe when solid reducing material blowing is stopped 9 Flowmeter 10 Flow control valve 11 Valve 12 Check valve 13 Flexible hose

Claims (3)

  A gas reducing material blowing device installed and used in a blast furnace that performs an operation of blowing a solid reducing material and a gas reducing material into a furnace from a tuyere, and a plurality of gas reducing material blowing devices disposed on an outer periphery of a furnace body of the blast furnace A ring-shaped gas reducing material supply pipe, a gas reducing material blowing pipe connecting the ring-shaped gas reducing material supply pipe and a gas reducing material blowing lance installed in the tuyere, and the ring-shaped gas reducing material supply pipe A gas reducing material supply main for supplying the gas reducing material to the pipe, and a gas reducing material supply pipe for branching from the gas reducing material supply main to supply the gas reducing material to the ring-shaped gas reducing material supply tubes. In addition, a ring-shaped gas reducing material supply pipe dedicated to stopping the blowing of the solid reducing material disposed on the outer periphery of the furnace body of the blast furnace, a ring-shaped gas reducing material supply pipe dedicated to stopping the blowing of the solid reducing material, and the gas reduction Solid reducing material blowing connecting the material blowing lance To the blast furnace, which consists of a dedicated gas reducing material blowing pipe at the time of stopping and a dedicated reducing gas supply pipe at the time of stopping the blowing of the solid reducing material for supplying the gaseous reducing material to the ring-shaped gas reducing material supply pipe dedicated to the stopping of the blowing of the solid reducing material Gas reducing material blowing device.   In the blast furnace in which the solid reductant and the gas reductant are blown into the furnace from the tuyere using the apparatus according to claim 1, when the blowing of the solid reductant from the tuyere is stopped, The supply of the gas reducing material from the ring-shaped gas reducing material supply pipe to the lance for blowing the gas reducing material at the mouth is stopped, and the lance for blowing the gas reducing material from the ring-shaped gas reducing material supply pipe when the solid reducing material blowing is stopped is stopped. Of operating a blast furnace to supply gas reducing material to the furnace.   Compared to the flow rate of the gas reducing material supplied from the ring-shaped gas reducing material supply pipe before stopping the blowing of the solid reducing material, the dedicated ring-shaped gas reducing material supply pipe to the lance for blowing the gas reducing material when the solid reducing material blowing is stopped. The operating method of the blast furnace of Claim 2 which increases the flow volume of the gas reducing material to supply.

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