JP2007277630A - Method for controlling injection of fine powdery coal into blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the desired injection quantity can not be obtained when a calibration curve for deciding a targeted value for inner pressure in a tank corresponding to the injection quantity of fine powdery coal is used beyond the actual total pressure loss. <P>SOLUTION: When the fine powdery coal in the pressurized tank 7 is injected into a blast furnace 1 by supplying the pressurized gas into the pressurized tank 7 for storing the fine powdery coal; in a control method, with which the calibration curve, as a function of the relation between the targeted fine powdery coal quantity and the pressure loss from the pressurizing tank 7 to the blast furnace 1, is set and the pressure loss amount is obtained from this calibration curve and the targeted fine powdery coal quantity, and the pressurizing tank pressure is adjusted to a value adding the pressure in the furnace near a tuyere to the obtained pressure loss amount, the pressure loss value from the pressurizing tank 7 to the blast furnace 1 is obtained at the pre-setting timing during injecting the fine powdery coal into the blast furnace 1. Then, when this obtained pressure loss value is out of the pre-setting range and generates this value continuously for the number of times of the pre-set number or more, the average value of the pressure loss value continuously generated is obtained, and the above calibration curve is renewed by parallel shifting to the position passing this obtained average pressure loss value and the point of the injection targeted fine powdery coal quantity at this time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for controlling the injection of pulverized coal into a blast furnace.

  In blast furnace operation, as an alternative to coke, pulverized coal as auxiliary fuel with low cost, good flammability and high calorific value is blown in along with hot air from the hot blast furnace from the tuyere of the blast furnace to reduce hot metal production costs and produce The improvement of the nature is aimed at.

  As a pulverized coal injection control technology for a blast furnace, for example, as disclosed in Patent Document 1, a pulverized coal injection burner attached to a tuyere of a blast furnace and pulverized coal are stored and maintained at a higher pressure than the blast furnace. The pulverized coal in the feed tank is adjusted by adjusting the gas pressure of nitrogen gas for pressurization supplied from the pressurization line to the feed tank. The amount of eruption is adjusted. A carrier gas line is connected in the middle of the blowing pipe, and the pulverized coal is accelerated in the blowing pipe by the carrier gas supplied from the carrier gas line and blown into the pulverized coal blowing burner.

  In the control of pulverized coal injection, the pressure setting in the feed tank assumes one point in the normal operation state of the blast furnace, which is a method of controlling the injection of powder, and the pressure in the furnace in that state (pressure before tuyere), Based on pipe resistance such as pipe length, calculate the minimum pipe flow velocity at which pulverized coal does not clog, the nozzle tip speed and the pressure loss that becomes the solid-gas ratio, and the relationship between the pulverized coal injection amount and the pressure in the feed tank Asking for.

  The relationship between the pulverized coal injection amount and the pressure in the feed tank is stored as a calibration curve in the control device, and the feed tank pressure target value is set as the pressure in the feed tank corresponding to the target value of the pulverized coal injection amount. The amount of gas supplied from the pressurization line to the feed tank is adjusted so that the measured pressure in the feed tank becomes the feed tank pressure target value.

In addition, by controlling the blowing amount adjustment valve provided in the middle of the blowing pipe so that the differential pressure between the pressure in the feed tank and the furnace pressure is constant, the pressure fluctuation of the blast furnace, the wear of the blowing pipe, etc. Even when a disturbance element such as a characteristic change occurs, pulverized coal can be stably injected.
JP 2004-035913 A

  In conventional pulverized coal injection control, the amount of pulverized coal burner injection can be adjusted by adjusting the valve opening of the injection amount control valve for fluctuations in blast furnace pressure, etc., but the calibration determines the feed tank pressure. As described above, the line is determined in consideration of the total pressure loss obtained by assuming one point in the normal operating state of the blast furnace. Even if the pressure loss changes, the feed tank pressure is determined in consideration of the total pressure loss different from the actual pressure loss.

  For this reason, a plurality of calibration curves suitable for the total pressure loss pattern of the blowing tube are prepared in advance and replaced with the calibration curve closest to the total pressure loss pattern of the blowing tube. Does not correspond to the actual total pressure loss, so pulverized coal may not be blown in an appropriate amount.

  In addition, when a plurality of calibration curves suitable for the total pressure loss of the blow-in pipe are not prepared, it is necessary to change the setting of the calibration curve each time.

  Furthermore, conventionally, a blow amount adjustment valve is provided in the middle of the blow pipe, but the blow amount adjustment valve is worn by the pulverized coal that is gas-conveyed in the blow pipe.

  The present invention has been made to solve such a problem, and it is possible to instantaneously determine the optimum amount of powder and granule in response to the change in the total pressure loss of the blowing tube. Providing a method for controlling the injection of pulverized coal into a blast furnace that does not require adjustment of the flow rate of pulverized coal and other granular materials, and does not require major equipment modifications to existing facilities. For the purpose.

  The method for realizing the object of the present invention is to supply a pressurized gas to a pressurized tank in which pulverized coal is stored and blow the pulverized coal in the pressurized tank into a blast furnace. Set a calibration curve as a function of the pressure loss between the pressure tank and the blast furnace, obtain the pressure loss amount from this calibration curve and the target pulverized coal amount, and add the pressure inside the furnace near the tuyere to this calculated pressure loss amount. In the control method of adjusting the pressurized tank pressure to the value obtained, while the pulverized coal is being blown into the blast furnace, the pressure loss value to the pressurized tank and the blast furnace is obtained at a preset timing, and the obtained pressure If the loss value is out of the preset range and occurs continuously for the preset number of times, the average value of the continuously generated pressure loss values is obtained. Point of blast coal target And updates to translate the calibration curve at a position passing through.

  According to the method of the present invention, the calibration curve is updated so as to fit the total pressure loss of the blowing tube, so that the desired blowing material such as pulverized coal even if the environment such as the type of the granular material changes. The amount can be blown into a powder blow destination device such as a blast furnace.

  In addition, it is possible to cope with a software response without significantly modifying the piping system and the instrumentation system.

  Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

  FIG. 1 is a block diagram of a piping system and an instrumentation system of a granular material blowing control apparatus according to an embodiment of the present invention.

  In FIG. 1, a blast furnace 1 that is a method for controlling the blowing of granular material is provided with a plurality of tuyere 2, and a plurality of blow pipes 4 extending from an annular tube 3 are connected to the tuyere 2, and a hot stove (not shown) From each blow pipe 4 is supplied to each tuyere 2 through the annular pipe 3. A pulverized coal blowing burner 5 is attached to each tuyere 2. One end side of the blowing pipe 6 is attached to the pulverized coal blowing burner 5.

  The feed tank 7 is disposed at the lowest position of a pulverized coal replenishing device including a pulverized coal hopper (not shown) and the pulverized coal is replenished from the pulverized coal hopper. The pulverized coal is replenished when the pulverized coal in the feed tank 7 is emptied. At this time, the exhaust pressure valve 21 is opened, the inside of the feed tank 7 is opened to the atmosphere, and the pulverized coal is replenished.

  The feed tank 7 is connected to the other end of the blowing pipe 6, and pressurized nitrogen gas from a pressurized gas source (not shown) is supplied into the feed tank 7 through the pressurized line 8. At that time, the exhaust pressure valve 21 is closed, and the internal pressure of the feed tank 7 is maintained at a pressure higher than the internal pressure of the blast furnace 1.

  A pressurization control valve 22 is provided in the pressurization line 8, and the amount of pulverized coal ejected from the feed tank 7 to the blow-in pipe 6 can be adjusted by adjusting the valve opening degree of the pressurization control valve 22. To do. A carrier gas line 9 is connected in the middle of the blowing pipe 6, and the pulverized coal discharged by pressurization from the feed tank 7 is accelerated by the carrier gas supplied from the carrier gas line 9 to the blowing pipe 6, and the fine powder of the blast furnace 1 is used. Blow into the charcoal burner 5. The opening of the pressurizing control valve 22 is adjusted by the pressure controller 20, and the exhaust pressure valve 21 is closed when a pressure control signal is output from the pressure controller 20. The flow rate of the carrier gas supplied from the carrier gas line 9 to the blowing pipe 6 is adjusted by the carrier gas control valve 29, and the flow rate is adjusted so that the pulverized coal conveyed in the blowing pipe 6 does not cause the pipe clogging. .

  The feed tank 7 is configured such that the weight is detected by a load detector 23 such as a load cell, and the weight of the pulverized coal supplied to the feed tank 7 is detected by the load detector 23. The weight detection value of the supplied pulverized coal detected by the load detector 23 is output to the weight controller 24.

  On the other hand, an in-furnace pressure sensor 25 for detecting the in-furnace pressure is attached to the tuyere 2 of the blast furnace 1, and the detected value of the in-furnace pressure (tuyere pressure) detected by the in-furnace pressure sensor 25 is converted into the in-furnace pressure converter 26. Is converted into an output signal (in-furnace pressure signal) Pf, and the in-furnace pressure signal Pf is output to the calibration curve automatic adjusting device 52 described later and also output to the pressure controller 20.

  Further, the pressure in the feed tank 7 is detected by the tank internal pressure sensor 27, and the tank internal pressure detection value detected by the tank internal pressure sensor 27 is converted into an output signal (tank internal pressure signal) Pt by the tank pressure converter 28. The signal Pt is output to the calibration curve automatic adjusting device 52 and also output to the pressure controller 20.

  In this embodiment, the pressure controller 20 does not control the pressurization control valve 22 so that the tank internal pressure signal Pt matches the tank internal pressure target value ΔPs calculated by the function generator 51, but does not control the tank internal pressure target value. The pressurization control valve 22 is controlled so that the tank internal pressure signal Pt matches the signal Pst obtained by adding the furnace pressure signal Pf to ΔPs. That is, the tank internal pressure is determined in consideration of the total pressure loss of the blowing pipe 6.

  The function generator 51 in this embodiment updates the calibration curve corresponding to the actual total pressure loss of the blow-in pipe in the blast furnace operation, and the actual total pressure loss of the blow-in pipe is automatically adjusted by the calibration curve. Calculated by the device 52.

  The calibration curve automatic adjusting device 52 is a blast furnace which is a method for controlling the pressure of the feed tank 7 and the injection of granular material obtained as a difference (ΔP = Pt−Pf) between the tank internal pressure signal Pt and the furnace internal pressure signal Pf. The differential pressure from the pressure in the furnace of 1, that is, the total pressure loss ΔP of the blow-in pipe is calculated.

  The calibration curve may be updated in accordance with the total pressure loss ΔP calculated by the calibration curve automatic adjustment device 52 every time pulverized coal is replenished to the feed tank 7, but in this embodiment, a plurality of continuous pulverized coal replenishments. The calibration curve is updated when the change in total pressure loss for each time exceeds a specified value, and FIG. 2 is a flowchart showing the operation.

  In FIG. 2, when the calculation for updating the calibration curve is started, in step (hereinafter referred to as S) 1, the tank internal pressure signal Pt and the furnace internal pressure signal Pf with a pitch of 3 to 10 minutes (in this example, a pitch of 5 minutes) ΔP = Pt−Pf, which is the difference between the two, is calculated and the process proceeds to Step 2

  In Step 2, a differential pressure ΔPt = ΔP2−ΔP1 between the preset pressure difference ΔP2 between the feed tank and the blast furnace and ΔP1 obtained in Step 1 is calculated. That is, the pressure increase / decrease amount applied to the feed tank 7 is calculated.

  In step 3, the increase / decrease amount ΔPt of the feed tank 7 calculated in step 2 is compared with thresholds (α, −α) for determining whether or not the calibration curve needs to be updated. It is determined whether or not it is satisfied N times or more continuously.

  In Step 3, when the requirements of ΔPt> α and ΔPt <−α are satisfied but the requirement of N or more times in succession is not satisfied, the above steps are repeated N times, for example, 3 times in succession. Repeat until the above requirements are met.

  Then, when all the requirements of Step 3 are satisfied, the process proceeds to Step 4. That is, satisfying all the requirements of Step 3 determines that the fluctuation of the total pressure loss is not temporary but has changed reliably.

  In step 4, the average value ΔPq of ΔPt for N times is calculated, and the process proceeds to step 5.

  In step 5, ΔPr (ΔPr = β × ΔPq) obtained by multiplying ΔPq obtained in step 4 by gain β is calculated, and the process proceeds to step S6.

  In Step 6, ΔP3 (ΔP3 = ΔP2 + ΔPr) obtained by adding ΔP2 used in Step 2 to ΔPr calculated in Step 5 is calculated, and the process proceeds to Step S7.

  In step S7, the calibration curve is replaced with a calibration curve moved in parallel to the position passing ΔP3 obtained in step S6.

  As described above, by sequentially updating the calibration curve in this embodiment, the differential pressure between the feed tank pressure and the furnace pressure, that is, the total pressure loss ΔP of the blow pipe, is added to the pulverized coal injection amount SV-feed tank internal pressure. A calibration curve in which a function with the target value ΔPs is set is automatically fitted. For example, as shown in FIG. 1, a calibration curve before update is fitted to ΔP calculated by the calibration curve automatic adjustment device 52. This calibration curve will be used later, and always provides a calibration curve that matches the blast furnace status, the condition of the blown pipe, and the diversity of the total pressure loss pattern of the blown pipe as the coal type of the pulverized coal used increases. It became possible.

  In the above-described embodiment, pulverized coal is blown from the tuyere 2 of the blast furnace 1, but the present invention is not limited to this. Needless to say, the present invention can be applied to the case of blowing particles.

The block diagram of the piping system and instrumentation system of the blowing control apparatus which shows an embodiment of the present invention. The flowchart which shows the calibration curve update process in the blowing control apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blast furnace 2 Tuyere 3 Annular pipe 4 Blow pipe 5 Pulverized coal injection burner 6 Blow pipe 7 Feed tank 8 Pressurization line 9 Carrier gas line 20 Pressure regulator 21 Exhaust pressure valve 22 Pressure regulator 23 Load detector 24 Weight controller 25 In-furnace pressure sensor 26 In-furnace pressure converter 27 Tank internal pressure sensor 28 Tank pressure converter 29 Carrier gas control valve 51 Function generator 52 Automatic calibration curve adjustment device

Claims (1)

When a pressurized gas is supplied to a pressurized tank that stores pulverized coal and the pulverized coal in the pressurized tank is blown into a blast furnace, the target supply amount of the pulverized coal and the pressure loss to the pressurized tank and blast furnace are a function. A calibration curve is set, and the pressure loss is calculated from the calibration curve and the target pulverized coal quantity. The pressure tank pressure is adjusted to the value obtained by adding the pressure in the furnace near the tuyere to the calculated pressure loss. In the control method to
While the pulverized coal was being blown into the blast furnace, the pressure loss value to the pressurized tank and the blast furnace was obtained at a preset timing, and the obtained pressure loss value was outside the preset range and preset. If it occurs continuously more than the number of times, the average value of the continuously generated pressure loss value is obtained, and the calibration curve is passed to the position passing through the obtained average pressure loss value and the point of the target pulverized coal amount at that time. A method for controlling the injection of pulverized coal into a blast furnace, wherein the blast furnace is renewed by translating.

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