JP2015098647A - Method of detecting clogging of piping in dust coal blowing installation of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of detecting clogging of piping in a dust coal blowing installation of a blast furnace which is not affected by equipment arranged around the piping and can reduce the time from occurrence of clogging of dust coal in the piping to detection of the clogging, compared with conventional methods.SOLUTION: A method of detecting clogging of piping in a dust coal blowing installation of a blast furnace includes a step of calculating an absolute value of a differential pressure between a pressure measurement in an upstream air feeding system and a pressure measurement in a downstream air feeding system and a step of detecting clogging of piping by determining occurrence of dust coal clogging of the piping of the upstream air feeding system when the magnitude of the absolute value of the calculated differential value is equal to or greater than a pre-set upstream threshold value P1 and the pressure measurement in the downstream air feeding system is equal to or smaller than a pre-set first downstream threshold value B1 and determining occurrence of dust coal clogging of the piping of the downstream air feeding system when the magnitude of the absolute value of the calculated differential pressure is equal to or greater than a pre-set downstream threshold value and the pressure measurement value in the downstream air feeding system is greater than a pre-set second downstream pressure threshold value.

Description

  The present invention relates to a technique for detecting the occurrence of clogging of pulverized coal in piping in equipment for blowing pulverized coal into a blast furnace.

  Conventionally, in blast furnace operation, in order to reduce the amount of expensive coke used, a method of blowing finely pulverized coal into the interior of the blast furnace as a partial substitute for coke has been implemented. Pulverized coal is formed by crushing coal with a coal crusher in a dry atmosphere fed with hot air, collected with a bag filter, and then screened with a sieving device, with a particle size of less than a predetermined size. It is stored in the hopper and then supplied to the injection tank for blowing. The injection tank is connected to the blowing main pipe by a transport pipe, and the blowing main pipe is branched in the middle to form a plurality of branch pipes to reach the blast furnace tuyere.

  And by supplying compressed gas, such as nitrogen, to an injection tank, pulverized coal is sent out to transport piping, and is conveyed to the tuyere of a blast furnace via a blow-in main pipe and a branch pipe. A lance for blowing pulverized coal is provided at the tip of each branch pipe in the blast furnace tuyere, and the pulverized coal is blown into the blast furnace by the plurality of lances. The pressure in the injection tank is set higher than the internal pressure of the blast furnace, but the pressure in the injection tank is usually lower than that of the blow-in main. Therefore, it is difficult to blow pulverized coal into the furnace at a uniform and sufficient pressure from a plurality of blast furnace tuyeres only with the delivery pressure from the injection tank. Therefore, the pulverized coal dilution gas is added to the blow-in main. Often compressed air is fed and mixed.

  Thus, a solid-gas two-phase flow including pulverized coal and carrier gas is formed, and the pulverized coal is fed to the blast furnace tuyere. In the following description, a group of devices and pipes that form a flow path for feeding pulverized coal upstream from the junction between the transport pipe and the blow-in main pipe are collectively referred to as an upstream air delivery system. A group of devices and pipes that form a flow path for airing pulverized coal to the blast furnace tuyere on the downstream side are referred to as a downstream air transportation system. The above-described injection tank and transportation piping belong to the upstream air transportation system. In addition, pipes such as a blow-in main pipe, a branch pipe, and a lance belong to the downstream air transportation system (see FIG. 1).

Here, the pulverized coal is selected to have a particle size of not more than a predetermined particle size after removing pieces of wood, lint and other foreign matters in the collection by the bag filter and the sieving process by the sieving device as described above. . However, pulverized coal may be clogged in the piping of the upstream air transportation system or the downstream air transportation system due to changes in the pressure inside the blast furnace or other operating factors. When these pipes are clogged, the amount of pulverized coal blown in the direction of the blast furnace peripheral wall will be reduced or unevenly blown, making it impossible to inject pulverized coal according to the schedule of operations, which will deteriorate the furnace conditions of the blast furnace. .
Thus, clogging of the pulverized coal in the piping of the pulverized coal injection facility to the blast furnace causes a great loss to the blast furnace operation. Therefore, in pulverized coal injection operation, pulverized coal is required to flow smoothly without adhering to or clogging the piping, and it is desirable to detect this quickly when clogging occurs. ing.

  Then, when seeing the method of detecting the occurrence of such clogged piping, there are techniques described in Patent Documents 1 to 3. In the technique of Patent Document 1, an acoustic sensor is provided outside a pipe for supplying pulverized coal, and clogging in the pipe is detected from the output signal. The technology of Patent Document 2 focuses on the unburned area of pulverized coal at the blast furnace tuyere, installs a radiation temperature camera at the blast furnace tuyere, analyzes the image of the temperature distribution in the blast furnace tuyere, and clogs the lance. Is estimated. The technology of Patent Document 3 pays attention to the fact that the pulverized coal has a temperature of about 80 ° C., and when the pulverized coal is clogged in the pipe, the surface temperature of the clogged portion of the pipe changes, A thermocouple is attached to the surface of a pipe that is not easily affected, the surface temperature of the pipe is continuously measured, and the presence or absence of clogging is determined from the temperature change amount.

JP 09-0667605 A Japanese Patent Laid-Open No. 06-093317 JP 2001-040404 A

However, in the technique of Patent Document 1, it may be difficult in practice to eliminate the influence (noise) of sound generated from various facilities and devices arranged in the vicinity of the blast furnace. In the technique of Patent Document 2, a curved portion of a blow pipe may be disposed in front of the radiation temperature camera. Such a blow pipe blocks the tip of the lance from the viewing angle of the radiation temperature camera, so that image analysis is sufficiently performed. May not be possible. Moreover, in the technique of patent document 3, it is set as a position which attaches a thermocouple to piping, it is 1 m or more from a blast furnace core as a position which is hard to be influenced by temperature from surrounding facilities, and 1 m from both a hot-air annular pipe and a ventilation branch pipe. The surfaces of the branch pipes that are separated from each other are used. However, the position on the surface of the branch pipe that is not easily affected by the temperature from the peripheral equipment often varies depending on the season, the time zone, the operation status of the peripheral equipment, and the like, and it is difficult to specify the position in practice.
That is, even if the techniques of Patent Documents 1 to 3 are used, there is a problem that the influence of the equipment arranged around the piping cannot be completely excluded. In addition, in the case of the technique of Patent Document 3, since the pipe to be measured has specific heat, the surface temperature of the pipe changes and the temperature change is captured by the thermocouple and displayed as a stable measurement temperature. The problem of taking time also arises.

In this regard, when the present inventor verified the technique of Patent Document 3, it was found that it takes more than one minute until the occurrence of clogging is detected after clogging has actually occurred in the piping. If pulverized coal is continuously blown into the blast furnace for more than one minute after clogging occurs, the amount of pulverized coal blown down or unevenly blown, resulting in a very high possibility that the furnace conditions will deteriorate. Thus, even if the technique of Patent Document 3 is used, since it takes a considerable amount of time from the occurrence of clogging to detection of clogging, the start of recovery work for removing pulverized coal from the piping is delayed, and the furnace There was a problem that the deterioration of the situation could not be sufficiently suppressed.
The present invention has been devised to solve the above-mentioned unsolved problems, and in the method for detecting clogging of piping in the pulverized coal blowing equipment of a blast furnace, the influence of the equipment arranged around the piping is affected. An object of the present invention is to provide a technology that can reduce the time from when clogging of pulverized coal occurs in a pipe to when the occurrence of clogging is detected.

As a result of repeated testing and research from the above viewpoint, the present inventor has obtained the following knowledge regarding the pressure in the pipe when the pulverized coal is clogged in the pipe in the pulverized coal injection facility.
First, FIG. 2 shows changes in the pressure measurement value in the upstream air transportation system and the pressure measurement value in the downstream air transportation system when the pulverized coal is clogged in the upstream air transportation system, and the pulverized coal is in the downstream air transportation system. The same change when clogged with is shown in FIG. All of these were obtained when 130 to 150 kg of pulverized coal per ton of hot metal was blown into the blast furnace.

  The pulverized coal is stored in the injection tank after being processed by the coal crusher, bag filter, sieving device, and pulverized coal hopper, and is sent to the blast furnace tuyere by transport piping, blow-in mains, branch pipes, etc. It is what is done. 2 and 3, the pressure measurement value in the injection tank is used as the pressure measurement value in the upstream air transportation system, and the pressure measurement value in the blow-in main pipe is used as the pressure measurement value in the downstream air transportation system. ing.

  The value of 640 kPa shown in FIG. 2 shows a specific example of the representative value of the pressure measurement value in the blow-in main pipe before clogging occurs in the upstream air transportation system. As the representative value, for example, an average value, an intermediate value, or a mode value within a predetermined time can be used. The meaning of “representative value” used in the following description is also the same. Further, the value of 450 kPa shown in FIG. 2 shows a specific example of the representative value of the pressure measurement value in the blow-in main pipe after clogging occurs in the upstream air transportation system. Further, the value of 628 kPa shown in FIG. 2 shows a specific example of the representative value of the pressure measurement value in the injection tank before clogging occurs in the upstream air feed system.

  Similarly, the value of 640 kPa shown in FIG. 3 shows a specific example of the representative value of the pressure measurement value in the blow-in main pipe before clogging occurs in the downstream air transportation system. Further, the value of 686 kPa shown in FIG. 3 shows a specific example of the representative value of the pressure measurement value in the blow-in main pipe after clogging occurs in the downstream air feeding system. Further, the value of 628 kPa shown in FIG. 3 shows a specific example of the representative value of the pressure measurement value in the injection tank before clogging occurs in the downstream air feeding system.

Table 1 shows the pressure measurement values in the upstream air transportation system, the pressure measurement values in the downstream air transportation system, and the change in the absolute value of the differential pressure between these two pressure measurement values.

  As shown in FIG. 2, when the pulverized coal is clogged in the upstream pneumatic system at the time t = t0, the pulverized coal is not present in the blow-in main pipe of the downstream pneumatic system. The pressure loss becomes smaller. As a result, the pressure in the blow-in main pipe (downstream air feeding system), which was about 640 kPa before clogging, suddenly decreases to a pressure lower than the pressure in the injection tank (upstream air feeding system), and relatively quickly reaches about 450 kPa. It shows a decreasing trend of falling. On the other hand, the pressure of about 628 kPa in the injection tank (upstream air feed system) does not change greatly. In other words, the magnitude of the absolute value of the differential pressure between the upstream air-feeding system and the downstream air-feeding system once decreases, but thereafter increases and changes with time (see Table 1).

  Also, as shown in FIG. 3, when pulverized coal is clogged in the downstream air transportation system at the time t = t0, the pulverized coal does not move in the upstream air transportation system, so the inside of the injection tank (upstream air transportation system). The pressure of about 628 kPa does not change greatly. On the other hand, the pressure in the blow-in main pipe (downstream air feeding system), which was about 640 kPa before clogging, shows an increasing tendency that it gradually rises to about 686 kPa after t = t0. That is, the magnitude of the absolute value of the differential pressure between the upstream air transportation system and the downstream air transportation system gradually increases and changes (see Table 1).

The present invention has been made based on the above findings.
A method for detecting clogging of piping in pulverized coal injection equipment to a blast furnace according to an aspect of the present invention includes an injection tank storing pulverized coal, an upstream air transportation system having a transportation pipe connected to the injection tank, and a transportation pipe. A method of detecting clogging of a pipe in a pulverized coal blowing facility of a blast furnace comprising a blown main pipe connected to and connected to a blast furnace, and a pressure measurement value in the upstream air feeding system, The differential pressure calculating step for calculating the absolute value of the differential pressure between the pressure measurement value in the downstream air transportation system, and the magnitude of the calculated absolute value of the differential pressure is greater than or equal to a preset upstream threshold value When the pressure measurement value in the downstream air transportation system is equal to or lower than the first downstream pressure threshold value set in advance, it is determined that the pulverized coal is clogged in the piping of the upstream air transportation system, and the calculated difference The absolute value of the pressure When it is equal to or greater than the set downstream threshold value and the measured pressure value in the downstream air transportation system is larger than the second downstream pressure threshold value set in advance, the piping of the downstream air transportation system is clogged with pulverized coal. It is determined that it has occurred and includes a clogging detection step of detecting clogging of the pipe.

  According to the present invention, the differential pressure between the pressure measurement value in the upstream air transportation system and the pressure measurement value in the downstream air transportation system is determined, and the magnitude of the absolute value of the differential pressure is set on the upstream side. When the measured pressure value in the downstream air transportation system is equal to or higher than the threshold value and is equal to or lower than the downstream pressure threshold value, it is determined that clogging of pulverized coal has occurred in the piping of the upstream air transportation system, and the clogging is detected. When the absolute value of the differential pressure is equal to or greater than a preset downstream threshold value and the pressure measurement value in the downstream pneumatic system is equal to or greater than the downstream pressure threshold value, pulverized coal is connected to the downstream pneumatic system pipe. It is determined that clogging has occurred, and clogging is detected.

As described above, since the pressure measurement value in the pipe may be used for clogging measurement, there is no influence even if a device such as a blow pipe is provided in the vicinity of the pipe. The change in pressure in the pipe is hardly affected by disturbances such as heat and sound.
In addition, the pressure measurement value changes at approximately the same timing as the pressure in the upstream air transportation system or the pressure in the downstream air transportation system changes due to the occurrence of clogging in the pipe, so the differential pressure is also approximately linked to this. It changes at the same timing. For this reason, the time from the occurrence of clogging until the detection of clogging in the pipe is greatly reduced.

In the clogging detection step, the state where the absolute value of the differential pressure is not less than the upstream threshold and the pressure measurement value in the downstream air transportation system is not more than the downstream pressure threshold. It may be determined that pulverized coal has been clogged in the upstream air-pipe system when the upstream reference time set for a predetermined time has elapsed.
In the clogging detection step, a state in which the absolute value of the differential pressure is greater than or equal to the downstream threshold and the measured pressure value in the downstream air transportation system is greater than the downstream pressure threshold is set in advance. It may be determined that clogging of pulverized coal has occurred in the piping of the downstream air-feeding system when it continues for more than the downstream reference time.

  Therefore, according to the method for detecting clogging of piping in the blast furnace pulverized coal injection facility according to the present invention, it is not affected by the equipment arranged around the piping, and after clogging occurs in the piping, occurrence of clogging is prevented. The time until detection can be greatly shortened compared to the conventional method. Further, it can be determined whether the clogging has occurred in the upstream air transportation system or the downstream air transportation system. Thereby, it becomes possible to start subsequent recovery operation | movement rapidly, and the deterioration of the furnace condition by the fall of the amount of pulverized coal injection | pouring and nonuniform injection | pouring can be suppressed.

It is a block diagram which illustrates typically the outline of the pulverized coal injection facility in which the clogging detection method of piping in the pulverized coal injection facility of the blast furnace which concerns on embodiment of this invention is used. It is a graph explaining the change of each pressure measurement value in the upstream air transportation system and the downstream air transportation system when pulverized coal is clogged with the upstream air transportation system. It is a graph explaining the change of each pressure measurement value in the upstream air transportation system and the downstream air transportation system when pulverized coal is clogged with the downstream air transportation system.

  A method for detecting clogging of piping in a pulverized coal injection facility for a blast furnace according to an embodiment of the present invention (hereinafter, also simply referred to as “clogging detection method”) is used for air-feeding pulverized coal to a blast furnace. Measure the internal pressure of each of the pipes belonging to and the downstream air transportation system, and based on the differential pressure between the measured pressure values, the pulverized coal is either the upstream air transportation system or the downstream air transportation system It detects that the pipe is clogged. The configuration will be described below with reference to the drawings. In addition, the shape, size, or ratio of each facility and each device used in the clogging detection method shown in the drawing is appropriately simplified and exaggerated.

(Pulverized coal injection facility)
First, blast furnace pulverized coal injection equipment for carrying out a clogging detection method according to an embodiment of the present invention will be described with reference to FIG. The pulverized coal blowing equipment includes the above-described coal crusher (not shown), a bag filter (not shown), a sieving device (not shown), a pulverized coal hopper (not shown), and an injection tank 3 for blowing. Prepare. Further, the pulverized coal blowing facility has a transport pipe 4 connected to the injection tank 3 and a blow main pipe 5 connected to the transport pipe 4. The transport pipe 4 joins at the blowing main pipe 5 and the junction 6. The blow-in main pipe 5 branches at a branch portion 7 provided in the middle to form a plurality of branch pipes 8. A lance 9 for injecting pulverized coal that opens to the tuyere 11 of the blast furnace 10 is provided at the tip of the plurality of branch pipes 8, and the main blowing pipe 5 is connected to the tuyere 11 of the blast furnace 10.

  The pulverized coal blowing equipment is shown by an enclosure located on the left side in FIG. 1, and an upstream air feeding system that feeds pulverized coal to the blowing main pipe 5 upstream from the junction 6, and the center in FIG. 1. And a downstream air feeding system for airing the pulverized coal to the tuyere 11 of the blast furnace 10 on the downstream side from the joining portion 6, which is indicated by a box located on the right side. The injection tank 3 is provided with an upstream pneumatic system pressure gauge 1 that measures the internal pressure of the injection tank 3. In addition, a downstream air pressure system side pressure gauge 2 for measuring the pressure in the blow main pipe 5 is disposed in the blow main pipe 5 on the opposite side of the blast furnace 10 across the junction 6. The upstream air system side pressure gauge 1 continuously measures the pressure in the injection tank 3 and the downstream air system side pressure gauge 2 continuously measures the pressure in the blow-in main pipe 5 over time.

  When blowing pulverized coal into the blast furnace 10, as shown by the arrow on the upper left side in FIG. 1, first, compressed nitrogen is supplied to the injection tank 3 storing the pulverized coal to form a solid-gas 2 flow, Thereafter, the solid-gas 2 flow is sent to the junction 6 via the transport pipe 4. On the other hand, as shown by the arrow on the lower left side in FIG. 1, compressed air for diluting pulverized coal is supplied to the merging portion 6 from another upstream path, and the solid gas 2 is sent from the upstream air feed system. Merge with the stream. The pressure in the injection tank 3 is higher than the internal pressure in the blast furnace 10, and the pressure in the blow-in main pipe 5 is set higher than the pressure in the injection tank 3. The solid-gas 2 stream containing pulverized coal is blown into the blast furnace 10 via the blow-in main pipe 5, the plurality of branch pipes 8, and the lance 9.

(Clogging detection method)
Next, a clogging detection method used in the above-described pulverized coal injection facility will be described. First, the pressure in the injection tank 3 is measured using the upstream air system side pressure gauge 1 and the pressure in the blow-in main pipe 5 is measured using the downstream air system side pressure gauge 2. And while obtaining the pressure measurement value with time of the injection tank 3 and the blow-in main pipe 5, the absolute value of these differential pressures is calculated (differential pressure calculation step). When clogging of pulverized coal occurs in the piping belonging to the upstream air transportation system or the downstream air transportation system, the measured pressure value in the injection tank 3, the measured pressure value in the main injection pipe 5, and the measured pressure value in the injection tank 3 and the injection A characteristic change as shown in FIGS. 2 and 3 occurs in the differential pressure with respect to the pressure measurement value in the main pipe 5.

  Next, it is determined whether the pulverized coal is clogged with the piping of the upstream air transportation system or the piping of the downstream air transportation system. Specifically, the magnitude of the absolute value of the differential pressure calculated in the differential pressure calculating step is equal to or higher than the upstream threshold value P1, and the pressure measurement value in the downstream air transportation system is equal to or lower than the downstream pressure threshold value B1. When the state continues for the upstream side reference time T1 or longer, it is determined that clogging of pulverized coal has occurred in the piping of the upstream air transportation system, and clogging of the piping is detected. Further, the downstream reference time T2 is a state in which the magnitude of the absolute value of the calculated differential pressure is equal to or greater than the downstream threshold value P2, and the pressure measurement value in the downstream air transportation system is equal to or greater than the downstream pressure threshold value B2. When the above is continued, it is determined that the pulverized coal is clogged in the piping of the downstream air transportation system, and the clogging of the piping is detected. (Clogging detection step).

(Upstream threshold P1, upstream reference time T1, and first downstream pressure threshold B1)
The upstream threshold value P1, the upstream reference time T1, and the first downstream pressure threshold value B1 are all used to determine clogging in the upstream air transportation system. The upstream threshold value P1 is a pressure threshold value that is set in advance with respect to the magnitude of the absolute value of the differential pressure that changes. The upstream reference time T1 is a differential pressure (absolute value) that is greater than or equal to the upstream threshold value P1. Is a reference time that is set in advance with respect to the duration of the continuation, and the first downstream pressure threshold value B1 is a threshold value that is set with respect to the pressure value in the downstream air transportation system.

  As shown in FIG. 2, for example, when clogging occurs in the piping in the upstream air transportation system at time t = t0, the pressure measurement value in the downstream air transportation system, which has been substantially constant, rapidly decreases, and the upstream air Below the pressure measurement in the transmission system. The magnitude of the absolute value of the differential pressure represented by the vertical distance between the solid line graph and the broken line graph in FIG. For example, in the case of FIG. 2, the absolute value of the differential pressure between the pressure measurement value in the upstream air transportation system (about 640 kPa) and the pressure measurement value in the downstream air transportation system (about 628 kPa) is 12 kPa during normal operation. Degree. Further, the pressure measurement value of the downstream air transportation system is higher than the pressure measurement value of the upstream air transportation system.

However, when clogging occurs, the pressure measurement value in the downstream air transportation system decreases, becomes the same as the pressure measurement value in the upstream air transportation system, and falls below the pressure measurement value in the upstream air transportation system as time elapses. At the time point t = t _H, the measured pressure value in the downstream air transportation system further decreases after the absolute value of the differential pressure reaches the upstream threshold value P1. At this time, the magnitude of the absolute value of the differential pressure equal to or higher than the upstream threshold value P1 continues for the upstream reference time T1 (t _{H to} t1). The measured pressure value of the downstream air transportation system is in a state equal to or lower than the first downstream pressure threshold B1 at the time t = t1. Therefore, at the time of t = t1, it is determined that all the conditions for occurrence of clogging in the upstream air transportation system are satisfied, and clogging of pulverized coal is detected.

  When clogging occurs in the upstream air transportation system, the pressure in the downstream air transportation system decreases to about 450 kPa as shown in FIG. 2, and the absolute value of the differential pressure is about 178 kPa, which is the difference between the pressure difference before clogging. It expands to about 15 times the absolute value. That is, the absolute value of the differential pressure when clogging occurs in the upstream air transportation system is much larger than the absolute value of the differential pressure during normal operation. At this time, the measured value of the pressure in the downstream air-feeding system tends to decrease overall before and after the occurrence of clogging (t = t0), and does not turn to an increasing trend.

  Therefore, the upstream threshold value P1 in this case can be set to 100 kPa, the first downstream pressure threshold value B1 to 630 kPa, and the upstream reference time T1 to 3 seconds, for example. The upstream reference time T1 may be set based on data when a clogging has occurred in the past or simulation. A generally preferable value of the upstream threshold value P1 is about 50 kPa to 150 kPa, and the value of the upstream reference time T1 is about 1 second to 10 seconds. Further, the value of the upstream side threshold value P1 is determined to be a value in a range where the absolute value of the differential pressure during normal operation is +20 kPa as a lower limit and the upper limit is +150 kPa, based on the absolute value of the differential pressure during normal operation. You can also. For example, when the absolute value of the differential pressure during normal operation is 12 kPa, 32 kPa ≦ P1 ≦ 162 kPa. If the value added to the absolute value of the differential pressure during normal operation is less than 20 kPa for setting the lower limit value, it is possible to erroneously determine the fluctuation state of the differential pressure that may occur during normal operation as clogging in the upstream air transportation system. Increases nature. Further, if the value added to the absolute value of the differential pressure during normal operation for setting the upper limit value is greater than 150 kPa, the possibility of delaying the determination of clogging in the upstream air transportation system increases.

  The downstream pressure threshold B1 is set to detect that the pressure in the downstream air transportation system is lower than that during normal operation, and is smaller than the pressure in the downstream air transportation system during normal operation. It is preferable to set to. Further, the first downstream pressure threshold value B1 may be a measured value of the upstream pneumatic system pressure when the measured value of the pressure in the downstream pneumatic system suddenly decreases (t = t0 in FIG. 2). . In addition, the first downstream pressure threshold B1 can be a measured value of the upstream pneumatic system pressure in a state where pulverized coal clogging has not occurred. In addition, the first downstream pressure threshold B1 may be set to a value that is 1 kPa to 20 kPa smaller than a value at the time of downstream pressure measurement during normal operation (a pressure measurement value of the downstream air transportation system, for example, 640 kPa). it can.

(Downstream threshold P2, downstream reference time T2, and second downstream pressure threshold B2)
The downstream threshold P2, the downstream reference time T2, and the second downstream pressure threshold B2 are all used to determine clogging in the downstream air transportation system. The downstream threshold value P2 is a pressure threshold value that is set in advance with respect to the magnitude of the absolute value of the differential pressure that changes, and the downstream reference time T2 is a differential pressure (absolute value) that is greater than or equal to the downstream threshold value P2. The second downstream pressure threshold B2 is a threshold set with respect to the pressure value in the downstream air transportation system.

As shown in FIG. 3, for example, when clogging occurs in the piping in the downstream air transportation system at the time t = t0, the pressure measurement value in the downstream air transportation system that has been substantially constant gradually increases. Similarly to the case of 2, the magnitude of the absolute value of the differential pressure expressed by the vertical interval between the two graphs gradually increases and changes. For example, in the case of FIG. 3, the absolute value of the differential pressure between the pressure measurement value in the upstream air transportation system (about 640 kPa) and the pressure measurement value in the downstream air transportation system (about 628 kPa) is the same as in FIG. Similarly, it is about 12 kPa at the time of normal operation. However, when clogging occurs, the measured pressure value in the downstream air transportation system increases, and at the time t = t _L , the magnitude of the absolute value of the differential pressure reaches the downstream side threshold value P2, and then in the downstream air transportation system. The pressure measurement is further increased until t = t2. At this time, the absolute value of the differential pressure equal to or greater than the downstream threshold value P2 continues for the downstream reference time T2 (t _{L to} t1). Further, the pressure measurement value of the downstream air transportation system is in a state larger than the second downstream pressure threshold B2 at the time of t = t1. Therefore, at the time of t = t2, it is determined that all the conditions for occurrence of clogging in the downstream air transportation system are satisfied, and clogging of pulverized coal is detected.
When clogging occurs in the downstream air transportation system, the pressure in the downstream air transportation system increases to about 686 kPa as shown in FIG. 3, and the magnitude of the absolute value of the differential pressure increases to about 58 kPa. At this time, the average time from the start of the increase in the pressure measurement value in the downstream air transportation system until the expansion of the absolute value of the differential pressure converges was about 30 seconds when calculated based on past data.

  Therefore, the downstream threshold value P2 in this case can be set to 40 kPa, for example, and the downstream reference time T2 can be set to 20 seconds. The value of the downstream threshold value P2 is preferably set to about 25 kPa to 50 kPa, and the value of the downstream reference time T2 is preferably set to about 3 seconds to 30 seconds. Further, the value of the downstream side threshold value P2 is set to a value in a range in which the absolute value of the differential pressure during normal operation is +10 kPa as a lower limit and the upper limit is +50 kPa, based on the absolute value of the differential pressure during normal operation. It can also be determined. For example, when the absolute value of the differential pressure during normal operation is 12 kPa, 22 kPa ≦ P2 ≦ 62 kPa. If the value added to the absolute value of the differential pressure during normal operation is less than 10 kPa for setting the lower limit value, it is possible to erroneously determine the fluctuation state of the differential pressure that may occur during normal operation as clogging in the downstream air transportation system Increases nature. Further, if the value added to the absolute value of the differential pressure during normal operation for setting the upper limit value is larger than 50 kPa, the possibility of delaying the determination of clogging in the downstream air transportation system increases.

  When clogging occurs in the downstream air transportation system, as described above, the pressure in the downstream air transportation system tends to increase more than that during normal operation. Therefore, the downstream air pressure during normal operation is set as the second downstream pressure threshold B2. If a value comparable to the internal pressure in the transmission system, for example, the same value as the representative value, is set, it can be detected that the internal pressure in the downstream air supply system becomes larger than the second downstream pressure threshold B2. The first downstream pressure threshold value B1 and the second downstream pressure threshold value B2 may be set to B1 = B2 using the same value of 640 kPa, for example, but the first downstream pressure threshold value B1 is Since it is set with respect to the pressure measurement value in the downstream air-feeding system that decreases when clogging occurs, the second downstream pressure threshold B2 is not exceeded. That is, B1 ≦ B2. In the embodiment of the present invention, even if the calculated absolute value of the differential pressure exceeds the upstream threshold P1 and exceeds the downstream threshold P2, the first downstream pressure threshold B1 and the first By using the downstream pressure threshold value B2 of 2, it becomes possible to determine and distinguish whether clogging has occurred in the upstream air transportation system or in the downstream air transportation system.

  Thus, the upstream threshold value P1, the upstream reference time T1, the downstream threshold value P2, the downstream reference time T2, the first downstream pressure threshold value B1, and the second downstream pressure threshold value B2 are set. However, as described above, there is a time period in which the magnitude of the absolute value of the differential pressure is temporarily reduced when clogging occurs in the upstream air piping. Therefore, it is desirable that the upstream reference time T1 is set to a time longer than the obtained length of time by obtaining the length of the reduction time when the piping is clogged in the upstream air transportation system in the past.

  The clogging detection method according to the embodiment of the present invention is configured by the steps described above. Then, after clogging of pulverized coal is detected and the piping in which the clogging has occurred is specified, an operation for restoring the specified piping is started. Moreover, if the clogging detection method which concerns on embodiment of this invention is used, it can be set as a suitable clogging detection method especially in the pulverized coal blowing equipment which blows about 130-150 kg of pulverized coal per ton of hot metal.

  When the clogging detection method according to the embodiment of the present invention is used, after the clogging of pulverized coal occurs, the time until the clogging of the pipe is actually detected is on the order of several seconds. Further, in the same equipment as the pulverized coal injection equipment according to the embodiment of the present invention, when the method of detecting clogging from the amount of change in the surface temperature of the pipe using the thermocouple described in Patent Document 3 is used, clogging occurs. After that, it took more than a minute to detect the clogging. Therefore, the clogging detection time according to the embodiment of the present invention can greatly reduce the clogging detection time.

(effect)
According to the clogging detection method according to the embodiment of the present invention, the differential pressure between the pressure measurement value in the upstream air transportation system and the pressure measurement value in the downstream air transportation system is obtained, and the absolute value of this differential pressure is large. When the pressure is not less than the preset upstream threshold value P1 and the pressure measurement value in the downstream air feed system is not more than the preset first downstream pressure threshold value B1, fine powder is added to the piping of the upstream air feed system. It is determined that charcoal clogging has occurred, and clogging is detected. When the absolute value of the differential pressure is greater than or equal to the preset downstream threshold P2 and the measured pressure value in the downstream air delivery system is greater than the preset second downstream pressure threshold B2. Then, it is determined that clogging of pulverized coal has occurred in the piping of the downstream air transportation system, and the clogging is detected. In this way, clogging is measured using changes in pressure in the piping that are hardly affected by disturbances such as heat and sound, so even if a device such as a blow pipe is installed in the vicinity of the piping, it is not affected. Not receive.

The pressure measurement value changes at almost the same timing as the pressure in the upstream air transportation system or the pressure in the downstream air transportation system changes due to the occurrence of clogging in the pipe, and the difference is linked to the change in the pressure measurement value. The pressure also changes at approximately the same timing. Therefore, after the occurrence of clogging, the change in the differential pressure is quickly detected to detect clogging of the pipe, so that the time required to detect clogging can be greatly shortened. Under normal operating conditions, when clogging occurs, the pressure starts to change within a few seconds from the steady-state pressure without clogging, and in a relatively short time, the absolute value of the differential pressure and the downstream value described in the embodiments of the present invention. Since the state where the pressure measurement value in the air transportation system satisfies the pressure condition for detecting clogging begins to occur, the time from this steady state until the condition for satisfying the pressure condition for detecting clogging occurs as the clogging judgment condition. It can also be added. In general, the more up to the pressure satisfies condition that is determined to clogging from the steady state (t0~t H in FIG. _2, or T0～t L in FIG. ₃₎ time is a short time, a critical failure Therefore, it is necessary to take measures as soon as possible. For this reason, it is also preferable to use a determination criterion that takes into account the time from the steady state to the pressure condition determined to be clogged and the pressure change rate. For example, it can be added to the determination criterion for clogging that the time from the steady state to the pressure condition determined as clogging is 0.5 seconds to 15 seconds.

  According to the clogging detection method according to the embodiment of the present invention, the time until the occurrence of clogging is detected after the clogging of the pipe is not affected by the equipment arranged around the pipe. It can be greatly shortened. Further, it can be determined whether the clogging has occurred in the upstream air transportation system or the downstream air transportation system. Thereby, it becomes possible to start the operation | movement of subsequent recovery work rapidly, and the deterioration of the furnace condition by the fall of the amount of pulverized coal injection | throwing-in or non-uniform | heterogenous injection | pouring can be suppressed.

  Further, according to the clogging detection method according to the embodiment of the present invention, the case where the generation time of the differential pressure is less than a certain time is excluded using the upstream reference time T1. This eliminates the influence of erroneous measurement and determines the occurrence of clogging, so that clogging of the piping of the upstream air transportation system can be detected more accurately. Further, according to the clogging detection method according to the embodiment of the present invention, the case where the occurrence time of the differential pressure is less than a certain time is excluded using the downstream side reference time T2, so that, similarly to the upstream side reference time T1, It is possible to determine the occurrence of clogging by eliminating the influence of erroneous measurement, and more accurately detect clogging of piping in the downstream air transportation system.

(Other)
In the clogging detection method according to the embodiment of the present invention, the differential pressure between the pressure measurement value in the injection tank 3 and the pressure measurement value in the blow-in main pipe 5 is used. The site where the pressure is measured is not limited to these. In general, the pressure measurement in the upstream air transportation system is preferably performed on the injection tank or upstream side thereof, and the pressure measurement in the downstream air transportation system is preferably performed on the compressed air line upstream of the junction 6. The transportation pipe 4 and the branch pipe 8 may be used. For example, in place of the downstream air pressure system side pressure gauge 2 arranged upstream of the junction 6 shown in FIG. 1, a pressure gauge is provided in the branch pipe 8 to measure the pressure in the downstream air supply system. Also good. However, at this time, since clogging upstream of the position of the pressure gauge is detected, clogging of pulverized coal remains in the upstream air transportation system even if a change in the measured pressure value as shown in FIG. 2 occurs. It may occur in the main pipe 5 of the downstream air-feeding system instead of the pipe.

In the embodiment of the present invention, the case where the differential pressure between two pressure measurement values is used has been described. However, the present invention is not limited to this, and a plurality of differential pressures between the pressure measurement values are calculated using a plurality of pressure measurement values. Based on the above knowledge, if a method of detecting clogging is performed from the change in the absolute value of each differential pressure, it is possible to efficiently identify in which piping the pulverized coal is clogged. .
Further, in addition to the clogging detection method in the pulverized coal injection facility according to the present embodiment, a thermocouple or an acoustic sensor may be additionally provided in the piping in the upstream air transportation system or the downstream air transportation system. For example, by combining multiple thermocouples on the surface of a pipe at predetermined intervals to obtain changes in surface temperature and the clogging detection method according to this embodiment, the location where clogging occurs can be identified more efficiently. And the recovery operation can be performed promptly.

  Also, when the piping of the pulverized coal injection facility downstream (for example, the main injection pipe) is damaged due to the progress of clogging, the pressure in the main injection pipe rapidly decreases and the absolute value of the differential pressure is large. It expands rapidly. Therefore, it is configured to detect not only clogging but also breakage of the blowing main pipe by combining a rapid decrease in the pressure in the blowing main pipe and a sudden increase in the absolute value of the differential pressure. Also good. For example, a breakage detection threshold value Pz for detecting whether or not the blow main pipe is broken and a breakage detection reference time Tz are set in advance. When the pressure in the blow-in main pipe suddenly drops to a predetermined pressure and the differential pressure (absolute value) greater than or equal to the breakage detection threshold Pz continues for the breakage detection reference time Tz or more, You may make it detect that a pipe | tube was damaged. Generally, if the absolute value of the differential pressure is 500 kPa or more, there is a high possibility of damage to the piping. In addition to detecting clogging, the recovery operation of the pulverized coal blowing facility can be started more quickly by quickly detecting breakage of the blowing main.

  Although the present invention has been described by the embodiments disclosed above, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, it should be understood that various alternative embodiments, examples, and operational techniques will become apparent to those skilled in the art. The present invention includes various embodiments and the like not described in the present specification and drawings, and the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description. It is what

DESCRIPTION OF SYMBOLS 1 Upstream air system side pressure gauge 2 Downstream air system side pressure gauge 3 Injection tank 4 Transport piping 5 Blowing main pipe 6 Junction part 10 Blast furnace B1 1st downstream pressure threshold value B2 2nd downstream pressure threshold value P1 Upstream side Threshold P2 Downstream threshold T1 Upstream reference time T2 Downstream reference time

Claims (3)

An upstream tank system having an injection tank storing pulverized coal and a transport pipe connected to the injection tank; and a downstream system having a blow main connected to the transport pipe and connected to a blast furnace. A method for detecting clogging of piping in a blast furnace pulverized coal injection facility comprising:
A differential pressure calculating step for calculating an absolute value of a differential pressure between a pressure measurement value in the upstream air transportation system and a pressure measurement value in the downstream air transportation system;
The magnitude of the absolute value of the calculated differential pressure is not less than a preset upstream threshold value, and the pressure measurement value in the downstream air transportation system is not more than a preset first downstream pressure threshold value. When it is determined that clogging of pulverized coal has occurred in the piping of the upstream air transportation system,
The calculated absolute value of the differential pressure is greater than or equal to a preset downstream threshold, and the pressure measurement value in the downstream air delivery system is greater than a preset second downstream pressure threshold. When it is determined that clogging of pulverized coal has occurred in the piping of the downstream air transportation system, a clogging detection step of detecting clogging of the piping,
A method for detecting clogging in a pipe in a pulverized coal injection facility for a blast furnace.   In the clogging detection step, the absolute value of the differential pressure is not less than the upstream threshold value, and the measured pressure value in the downstream air transportation system is not more than the first downstream pressure threshold value. In the blast furnace pulverized coal injecting equipment according to claim 1, wherein it is determined that clogging of pulverized coal has occurred in the piping of the upstream air transportation system when continuing for a preset upstream reference time or longer. Piping clogging detection method.   In the clogging detection step, the state where the magnitude of the absolute value of the differential pressure is not less than the downstream threshold value and the pressure measurement value in the downstream air transportation system is larger than the second downstream pressure threshold value, 3. The blast furnace pulverized coal injection facility according to claim 1, wherein it is determined that clogging of pulverized coal has occurred in the piping of the downstream air transportation system when continuing for a preset downstream reference time or longer. Detection method for clogged pipes.

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