JP2006063417A - Method for canceling clogging in nozzle of facility for blowing pulverized coal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for effectively canceling clogging in a nozzle of a facility for blowing pulverized coal, without stopping the operation of an injection tank and giving an unfavorable influence on maintenance for the tank. <P>SOLUTION: The method for canceling the clogging in the nozzle comprises the steps of: when the clogging occurs in the nozzle, separating one part of a pneumatic tube having caused the clogging in the nozzle; connecting a hose attached to a dusting machine having an appearance side opened to the atmosphere, with the pneumatic tube of the nozzle side; and applying a differential pressure between the internal pressure of the tank and atmospheric pressure, to the clogging part of the nozzle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for effectively releasing nozzle clogging in a transportation system generated in a pulverized coal injection facility.

  In an apparatus using pulverized coal, such as a blast furnace, pulverized coal is blown into a furnace body from a tuyere and used as a source for generating fuel and reducing gas.

  For example, FIG. 3 shows a system of air feeding paths for conveying the pulverized coal 1 by gas to the injection lance 7 inserted into the tuyere 8. The pulverized coal injection facility to the blast furnace uses the injection tank 2 containing the pulverized coal 1 as a pressure vessel, and the tank internal pressure is the pressure in the tuyere 8 in order to carry the pulverized coal 1 into the blast furnace tuyere 8 by gas. Set higher. For example, depending on the blast furnace, the pressure in the tuyere 8 is about 300 to 600 kPa, so the pressure of the gas in the injection tank 2 is set to a pressure 100 to 200 kPa higher than that, and this pressure difference The pulverized coal 1 together with the gas is conveyed by gas to the injection lance 7 through the pneumatic piping 41, 42, 43, 44 and blown into the blast furnace.

  Therefore, in the pulverized coal injection equipment to the blast furnace, the gas pressure in the injection tank 2 is set to a tank internal pressure of 400 to 800 kPa according to the pressure in the tuyere 8.

  Since the blast furnace is provided with a plurality of tuyere 8, there are only a number of transportation systems corresponding to the number, but FIG. 3 shows only one air transportation route. The air feeding path shown in FIG. 3 includes the air feeding pipes 41, 42, 43, and 44 and the on-off valves A, B, C, and D. In FIG. 3, 2A denotes a dispersion plate disposed in the tank, and 2B denotes a nitrogen pipe for aeration for supplying nitrogen into the tank. E indicates an aeration stop on-off valve.

  In general, in a blast furnace, compressed nitrogen is used as a gas for conveying the pulverized coal 1 as a gas, and the pulverized coal 1 can be conveyed by gas from one injection tank 2 to each tuyere 8 through a plurality of air supply paths. . Here, the pulverized coal 1 is usually dried and adjusted to an average particle size of about several tens of μm, and then stored in the injection tank 2. A piping for introducing booster air is connected to the air feeding path 42 for conveying the pulverized coal 1, and the transport amount per unit time of the pulverized coal 1 can be controlled by the amount of the booster air.

  However, depending on the brand of the pulverized coal 1 and the properties of the pulverized coal 1 such as the water content and particle size, nozzle clogging may occur in the nozzle 3 portion into which the pulverized coal 1 aerated with aeration nitrogen flows. Nozzle clogging occurs when the pulverized coal is partially wetted or agglomerated to deteriorate transportability.

As a countermeasure against nozzle clogging in such pulverized coal injection equipment, Patent Document 1 grasps the tendency of clogging easily and clogging difficulty for each coal type of pulverized coal, and mixes these coal types to create a nozzle. Propose to reduce clogging. Patent Document 2 proposes a method for detecting nozzle clogging that has occurred in pulverized coal blowing equipment.
JP 2003-286510 A JP 2001-40404 A

  However, in the pulverized coal injection facility, there was no method for effectively eliminating nozzle clogging that actually occurred and transporting the pulverized coal 1 by gas again.

  Generally, as shown in FIG. 3, by closing the on-off valve C disposed in the middle of the route of the transportation system in which nozzle clogging has occurred, by increasing the internal pressure of the pipe in the middle of the route by booster air pressure, The pulverized coal clogged in the nozzle was pushed back into the injection tank 2 to eliminate clogging.

  The air pressure that can be increased by the booster is 100 to 200 kPa at most with respect to the tank internal pressure when the pulverized coal 1 is conveyed by gas. Therefore, when the pulverized coal is firmly clogged in the nozzle, the nozzle Sometimes clogging cannot be cleared. In FIG. 3, 9 indicates the supply direction of the booster air.

  When the nozzle clogging has failed to be released by such a method, the operation of the injection tank 2 is stopped, the tank internal pressure is released, and the nozzle is clogged with the tank internal pressure set to atmospheric pressure. There is no choice but to scrape the pulverized coal directly. When the method of directly scraping the pulverized coal clogged in the nozzle in a state where the tank internal pressure is atmospheric pressure, it takes 8 to 24 hours until the nozzle clogging is released.

  For this reason, normally, the injection of the system with clogged nozzles is stopped and the remaining system is continued to be injected, but this makes the pulverized coal injection position uneven within the furnace, leading to blast furnace operation. May cause adverse effects. Further, when a plurality of nozzles are clogged, the above-described injection is stopped and the nozzle clogging is released, which may also adversely affect blast furnace operation.

  In addition, by increasing the internal pressure of the pipe in the middle of the path by booster air pressure, if the nozzle clogging has been successfully released, the pulverized coal clogged in the nozzle is ejected into the injection tank 2. In the facility for forming a fluidized bed on the front surface of the nozzle as shown in FIG.

  In addition, by successfully increasing the internal pressure of the pipe along the path by booster air pressure, if the nozzle clogging is successfully released, the pulverized coal clogged in the nozzle is returned into the injection tank 2, This also causes a problem that nozzle clogging may occur again.

  Accordingly, an object of the present invention is to propose a nozzle clogging release method in a pulverized coal injection facility effectively without stopping the operation of the injection tank and without adversely affecting the maintenance of the tank.

  As a result of intensive studies, the present inventor has obtained knowledge that nozzle clogging can be released by utilizing the tank internal pressure of the injection tank, and the present invention has been made based on this knowledge.

  The present invention is a nozzle clogging release method in a pulverized coal blowing facility that gas-carrys pulverized coal from a nozzle arranged in an injection tank to an apparatus that uses pulverized coal via an air feed pipe, and nozzle clogging has occurred. At that time, cut off the part of the air supply pipe where the nozzle clogging occurred, connect a dust remover whose outlet side is open to the atmosphere to the nozzle side air supply pipe, and the difference between the tank internal pressure and atmospheric pressure at the nozzle clogging part. A nozzle clogging release method for pulverized coal blowing equipment, wherein pressure is applied to release nozzle clogging.

  According to the present invention, the operation of the injection tank is not stopped, the tank maintenance is not adversely affected, and the nozzle clogging of the pulverized coal blowing facility can be effectively released.

  In the conventional method in which the internal pressure of the pipe in the course is increased by the booster air pressure, the differential pressure that can be applied to the nozzle clogging portion by closing the blast furnace side open / close valve C and the booster air pressure is much higher than the tank internal pressure. Since it is 100 to 200 kPa, it sometimes fails to eliminate nozzle clogging.

  On the other hand, in the present invention, the conventional method described above according to the pressure difference between the tank internal pressure and the atmospheric pressure when the pulverized coal is conveyed to the nozzle clogging portion at the maximum, that is, the pressure in the tuyere 8. Since higher pressure differentials of 400-800 kPa can be applied, in most cases, nozzle clogging was successfully removed.

  Therefore, according to the present invention, there is almost no adverse effect on the operation of an apparatus using pulverized coal such as a blast furnace.

  Further, according to the present invention, a part of the air supply pipe in which the nozzle clogging has occurred is cut off, and a hose provided with a dust remover that communicates with the atmosphere on the outlet side through the filter is connected to the air supply pipe on the nozzle side, Since the nozzle clogging is released, the pulverized coal clogged in the nozzle can be collected by the filter of the dust remover, and the pulverized coal clogged in the nozzle is returned to the injection tank as in the conventional method. Compared with, it is possible to reduce the possibility of reoccurrence of nozzle clogging.

  At this time, according to the present invention, the nozzle clogging is released, and at the same time, the pulverized coal in the injection tank 2 is collected by the filter of the dust remover through the air supply pipe and the hose in the middle. It can be prevented from scattering.

  The nozzle clogging release method according to the present invention will be described with reference to FIGS.

  It is assumed that nozzle clogging occurs in the transportation system shown in FIG. 1 and 2 that are the same as those in FIG. However, it is assumed that the operation of the injection tank 2 is continued and pulverized coal is being injected into the blast furnace by another transportation system in which nozzle clogging has not occurred.

  In FIG. 1, 6 indicates a dust remover with a built-in filter 6A, and 6B indicates a dust collection chamber. The dust remover 6 communicates with the atmosphere through the filter 6A, and the hose 5 is connected to the dust collection chamber.

  In the nozzle clogging release operation described below, the injection tank 2 is operated, and the nozzle clogging release operation is performed in a state in which the pressure in the tank is the pressure when the pulverized coal 1 is conveyed by gas. The dust chamber 6B is subjected to a differential pressure between the tank internal pressure and the atmospheric pressure when the pulverized coal 1 is conveyed by gas. Therefore, the specification that can be used for it is used.

  Here, it is assumed that the air feed pipe 43 is disconnected at two flange joints in the middle of the transport system, and the hose 5 attached to the dust remover 6 whose outlet side communicates with the atmosphere is connected via the flange. Connecting the hose 5 attached to the dust remover 6 whose outlet side communicates with the atmosphere through the flange in the middle of the transportation system in which nozzle clogging has occurred in this way is a recovery work for the disconnected pneumatic piping. Since it can be performed in a short time, it is preferable.

  In this case, the air feed pipe 43 is cut off at the two flange joints of the on-off valves A and C, and as shown in FIG. 2, the hose 5 is connected to the air feed pipe 42 where the nozzle clogging has occurred via the flange. Connected. However, since the operation of the injection tank 2 is continued and pulverized coal is blown into the blast furnace by another transportation system in which nozzle clogging does not occur, the nozzle clogging is necessary before disconnecting the pipe and performing connection work. Close the on-off valves A, B, C and D of the transportation system where

  In such a state where the operation of the injection tank 2 is continued, the on-off valves A, B, C and D are closed, and as shown in FIG. 6 is connected, and the nozzle clogging is released.

  In the nozzle clogging release procedure, the on-off valves A and B are opened in the order of the valves A and B. At that time, when the valve A is fully opened and then the valve B is opened, it is preferably performed instantaneously. By doing in this way, the differential pressure which acts on a nozzle clogging part can be made into the differential pressure of the tank internal pressure when carrying pulverized coal 1 by gas at the maximum, and atmospheric pressure. If the opening / closing valves A and B are reversed and the valves B and A are opened in this order, the nozzle clogging release operation procedure can be performed instantaneously when the valve B is fully opened and then the valve A is opened. Since the differential pressure acting on the nozzle clogging portion is the same, either may be used. The differential pressure between the tank internal pressure and the atmospheric pressure is set to a differential pressure of 400 to 800 kPa because pulverized coal is blown by another transport system at the start of the nozzle clogging release operation.

  Therefore, the nozzle clogging release method in the pulverized coal blowing facility according to the present invention is configured to obtain a differential pressure between the tank internal pressure and the atmospheric pressure when the pulverized coal 1 is conveyed by gas to the nozzle clogging portion, that is, a differential pressure of 400 to 800 kPa. In most cases, nozzle clogging is successfully removed.

  As the dust remover 6, a dedicated one may be installed around the injection tank 2, or a portable type may be used. The filter 6A can be a bag filter. The hose 5 attached to the dust remover 6 can use an appropriate piping member such as a flexible tube.

  The pulverized coal injection facility is not limited to a blast furnace. In addition, as a method for releasing nozzle clogging in pulverized coal injection equipment, a T branch is provided in advance in the pneumatic piping and this T branch is set as a valve stop. When nozzle clogging occurs, this valve stopped T branch pipe Further, the hose 5 attached to the dust remover 6 whose outlet side communicates with the atmosphere may be connected, and the nozzle clogging may be released by the differential pressure between the tank internal pressure and the atmospheric pressure when the pulverized coal 1 is conveyed by gas. .

In a blast furnace with an internal volume of 5000 m ^3, a total of 40 ton / h of pulverized coal was injected into the tuyere 8 at 40 locations around the blast furnace. The pressure inside the tuyere 8 is 600 kPa, and the tank internal pressure when the pulverized coal 1 in the injection tank 2 is conveyed by gas is set to 700 kPa.

  In the conventional nozzle clogging release method in which the internal pressure of the pipe in the path is increased by booster air pressure, 12 nozzles were successfully released during nozzle clogging that occurred 22 times in 3 months, but 10 times failed.

  Therefore, the operation of the injection tank 2 was stopped twice during three months, and the inside of the injection tank 2 was brought to atmospheric pressure, and then the clogged nozzles 3 were cleaned and some of the nozzles 3 were replaced. This stop time was about 12 hours per time, and the pulverized coal injection into the blast furnace tuyere 8 had to be stopped for a total of 24 hours in 3 months.

  The present invention was applied to the blast furnace for 3 months thereafter. During this period, in the pulverized coal injection facility to the blast furnace, all 16 occurrences of nozzle clogging succeeded. As a result, after applying the method of the present invention, pulverized coal can be stably injected into the tuyere 8 of the blast furnace.

  In the conventional method, even when the nozzle clogging was able to be released, there was a case where the nozzle clogging occurred again within one hour thereafter. However, after the method of the present invention was applied, there was no such nozzle clogging.

It is the schematic explaining the nozzle clogging cancellation method concerning this invention. It is the schematic which shows the connection state of piping which is implementing this invention. It is the schematic explaining the conventional nozzle clogging cancellation | release method.

Explanation of symbols

1 Pulverized coal 2 Injection tank (pressure vessel)
2A Dispersing plate 2B Nitrogen piping for aeration 3 Nozzles 41, 42, 43, 44 Pneumatic piping 5 Hose A, B, C, D, E Open / close valve 6 Dust remover 6A Filter 6B Dust collection chamber 7 Injection lance 8 Tail 9 Booster Air supply direction

Claims (1)

A nozzle clogging release method in a pulverized coal blowing facility for pneumatically transporting pulverized coal from a nozzle arranged in an injection tank to an apparatus using pulverized coal via an air feeding pipe,
When nozzle clogging occurs, cut off part of the air supply pipe where the nozzle clogging occurred, connect a dust remover with the outlet side open to the atmosphere, and connect the internal pressure of the tank to the nozzle clogging part. A method for removing nozzle clogging in a pulverized coal blowing facility, which applies a pressure difference from atmospheric pressure to release nozzle clogging.

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