JP2006077267A - Powder blowing equipment - Google Patents

Abstract

A powder having a powder flow rate measuring system capable of accurately measuring a powder flow rate even when the powder type is changed and powder adheres to the capacitance type powder flow meter. Providing infusion facilities.
A powder blowing facility includes a powder flow rate measuring system that performs the following signal processing on the measured value of a capacitance type powder flow meter. In order to correct the measured value by detecting powder adhesion etc. in the flow meter, the detector output signal is monitored when powder blowing is stopped, and if it exceeds a predetermined value, the detector output signal is corrected to a predetermined value. I do. In order to prevent measurement errors due to changes in the type of powder, the powder flow rate is corrected by comparing the flow rate value obtained by the electrostatic capacitance type powder flow meter with the change in the weighing value of the powder in the feed tank. Further, in order to avoid erroneously outputting the powder flow rate due to the gas component and humidity change during the branch pipe purge at 21, the powder flow rate masking process is performed for a certain period of time during stoppage and after the start of blowing.
[Selection] Figure 2

Description

  The present invention relates to a powder blowing facility equipped with a measurement system that continuously and stably measures the flow rate of powder conveyed by gas in a powder blowing facility such as a blast furnace or a power plant in the steel industry.

For example, in the operation of a blast furnace in the steel industry, iron ore and coke are alternately fed from the top of the furnace and iron ore is reduced by blowing hot air mixed with pulverized coal from a blower tuyere placed at the bottom of the blast furnace. Remove pig iron. The main purpose of blowing the fine powder is to suppress the introduction of expensive coke.
Now, in order to keep the reaction in the blast furnace stable for the injection of pulverized coal, keep the injection amount (circumferential balance) for each blower tuyere uniform, and the same amount of powder into the furnace Insufflation is necessary.
Therefore, there are the following two methods of measuring the amount of powder blown conventionally performed.
The first method is visual confirmation by an operator. This is a system in which a transparent part such as a glass part is provided in the piping of a conveying line during gas conveyance, and the lightness and density varying with the concentration of the powder is visually confirmed from the outside of the piping.

As a second method, there is a method using a capacitance type powder flow meter as disclosed in Patent Document 1 below. Two pairs of spiral electrodes are placed on the powder transfer line, and the powder concentration is measured based on the change in capacitance caused by the change in the powder transfer amount. In this method, the flow rate is obtained from the time difference between the changes in the electrostatic capacity, and the powder flow rate is obtained from the measured concentration and flow rate.
The problems in the conventional method described above are as follows.
The visual confirmation method cannot measure the powder flow rate quantitatively and stably.
Conventional capacitance powder flowmeters are capable of continuous measurement of powder flow rate. However, powder that adheres to the inside of the capacitance measurement electrode in the pipe and flows continuously. May not be measured accurately. Further, when the composition of the powder passing through changes, the electrical characteristics change, so that the capacitance changes and a measurement error occurs.
Japanese Patent Application No. 11-196961

As described above, in a powder blowing facility such as a blast furnace or a power plant, it is important for stable operation of the blast furnace or the like to stably measure the powder flow rate with high accuracy.
The present invention has been made to solve these problems, and a powder blowing facility equipped with a powder flow rate measurement system capable of continuously and stably measuring regardless of the type of powder. The purpose is to provide.

The first invention of the present application is a plant for blowing powder through a pipe with carrier gas in a plant such as a blast furnace or a power plant.
A feed tank having a weighing device for storing powder, a carrier gas supply means, a distributor tank for storing a powder gas mixed gas of powder and carrier gas, and connecting the feed tank and the distributor tank A main pipe part, a single or a plurality of branch pipe parts for blowing the powder gas mixed gas in the distributor tank into the plant, a branch pipe purge line for purging the powder gas mixed gas from the branch pipe part, A powder blowing facility comprising a powder flow rate measuring system for measuring a body blowing amount, wherein the powder flow rate measuring system is a capacitance type powder flow meter attached to the branch pipe part. In addition, with respect to the output signal of the capacitance type flow meter, the zero point adjustment unit for correcting the zero point of the powder flow rate, and the change of the output signal due to the type and concentration fluctuation of the powder. A powder blowing equipment comprising a powder concentration correction unit for correcting movement.

For electrostatic capacity type powder flowmeters, output signals when the concentration of powder flowing continuously cannot be measured accurately due to the occurrence of powder adhesion inside the capacitance measurement electrode in the pipe. The zero point of the value was corrected, and the change in capacitance when the composition and concentration of the passing powder changed was corrected so that the powder flow rate could be measured continuously and accurately.
According to a second invention of the present application, in the first invention, the powder flow rate measurement system includes a capacitance type powder flow meter, a zero point adjustment unit, and a powder concentration correction unit,
Each of a flow rate calculation unit that calculates the flow rate of the powder gas mixed gas, a count correction unit that converts an output signal of the capacitance type powder flowmeter into a powder flow rate, the flow rate calculation unit, and the powder concentration correction unit A powder flow rate output unit for calculating a powder flow rate from the output value, and a powder flow rate for correcting fluctuations in the measured powder flow rate at the time of branch purge for the measured powder flow rate of the capacitance type powder flow meter A powder blowing facility comprising a mask processing unit.
According to a third aspect of the present invention, the zero point adjustment unit is configured such that the capacitance type powder flowmeter is operating normally with respect to an output signal value of the capacitance type powder flowmeter, and the powder gas When the mixed gas is not in the branch pipe, the previous output signal value is measured in advance to obtain an initial value C. When the powder blowing is stopped thereafter, the output signal value is measured as A, and the difference between A and C is calculated. When the absolute value exceeds a predetermined value, (AC) is obtained as a zero point correction value, and the output signal value A ′ of the capacitance type powder flow meter at the time of powder blowing is expressed as (A ′ − ( A powder injection equipment according to the first invention or the second invention, wherein the powder injection equipment is corrected to AC)).

According to a fourth aspect of the present invention, the powder concentration correction unit is configured to reduce the amount of powder in the feed tank during a predetermined period T measured by a weighing device installed in the feed tank, and the capacitance type powder flow rate. Comparing the sum of the integrated values in the predetermined period T of the powder blowing amount measured with a meter, the output signal value of the capacitance type powder flow meter is corrected, The powder blowing facility according to one of the first to third inventions.
According to a fifth aspect of the present invention, the powder flow rate mask processing unit is configured to clean the powder flow rate of the capacitance type powder flow meter by flowing only a gas through a branch pipe of the powder blowing facility. Forcibly masking, and the predetermined time after the end of gas cleaning is corrected to the value immediately before the start of gas cleaning or a predetermined flow rate determined in advance. It is the powder blowing equipment described in one.

  According to the present invention, when an electrostatic capacitance type powder flow meter is installed in the branch of the powder blowing equipment and the powder flow rate is measured, adhesion of the powder occurs inside the capacitance measuring electrode in the branch. As a result, the zero point of the output signal value is corrected when the concentration of the continuously flowing powder cannot be measured accurately, and the change in capacitance when the component or concentration of the passing powder changes is corrected. In addition, a powder blowing facility capable of continuously and accurately measuring the powder flow rate, which is equipped with a powder flow rate measurement system that corrects fluctuations in the powder flow rate during the purge of the branch pipe, has become possible.

The best mode for carrying out the invention of the present application will be described with reference to the drawings.
FIG. 1 (a) is an outline of an example of the powder blowing equipment of the present invention, and in particular, an explanation will be given taking a powder blowing equipment of a blast furnace as an example. In the powder blowing equipment of the blast furnace, the powder is accumulated in a hopper tank (hereinafter referred to as a feed tank) 1 equipped with a weighing device 2, and then passed through a distributor (hereinafter referred to as a distributor tank) 4 by a gas carrier gas 3. Feed to multiple branch pipes and inject into blast furnace. A capacitance type powder flow meter 9 was attached to each branch pipe of the powder blowing apparatus. In this example, as shown in FIG. 1 (b), ten branch pipes of the same number as the blower tuyere are connected to the outlet side of the distributor tank 4.
FIG. 2 shows the system configuration of the present invention. Reference numeral 11 denotes a capacitance type powder flowmeter main body (only one branch pipe is shown), and 12a and 12b are equipped with capacitance type detectors (including electrodes). Reference numeral 13 denotes a detector output signal obtained by the detector 12a, and the zero point adjustment unit 14 corrects and monitors the output signal.
The function of the zero point adjustment unit 14 will be described with reference to FIG.

FIG. 3 shows the detector output signal when the powder blowing equipment is stopped. The detector output signal changes the zero point of the detector output signal value from the initial value due to the occurrence of material wear due to powder adhering to the inside of the flowmeter or friction through the powder, causing an error in the flow rate indication value. . Note that the detector output signal value varies to the + side (A) when powder adheres to the inside of the flow meter due to the electrode structure of the capacitance powder flow meter, and the flow meter piping is worn. In such a case, it changes to the-side (B).
FIG. 4 is a flowchart of signal processing of the zero adjustment unit. The initial value C is measured in advance when the electrostatic capacity detector is normally operating and the powder blowing is stopped. When the output value when the powder blowing is stopped exceeds a predetermined absolute value D (for example, in the case of A in FIG. 3), an alarm is issued and the initial value C (from FIG. 3) is determined. The zero point correction value (A−C) is obtained by calculating a difference from the reference). At the time of powder blowing, the zero point correction output value is obtained by subtracting this zero point correction value from the detector output signal value (A ′). (Zero point correction output value = A ′ − (AC)).

The count correction unit 15 in FIG. 2 performs count correction for converting the zero point correction output value obtained by the zero point adjustment unit 14 into a powder concentration. In the capacitance type powder flowmeter, as shown in FIG. 5, since the relationship between the detector output signal and the actual powder concentration is linear, the count correction unit 15 performs count correction by a primary expression. Yes.
The flow velocity calculation unit 18 in FIG. 2 calculates the flow velocity by obtaining a time difference between output signals appearing at the detectors 12a and 12b. In FIG. 2, if 12a is installed on the upstream side of the pipe and 12b is installed on the downstream side and powder blowing is performed, an output signal generated when the powder passes through 12a appears on 12b after a certain period of time. The flow velocity is calculated from the time delay of the output signals of 12a and 12b.

The powder concentration correction unit 16 in FIG. 2 performs powder concentration correction calculation. That is, in the powder blowing equipment of the blast furnace, the powder type and powder mixed with a plurality of components are used in consideration of the price of the powder and the reaction in the blast furnace. At this time, the output signal value obtained from the detector changes due to the difference in the electrical characteristics of the powder, and a measurement error may occur due to the count correction performed by the count correction unit 15. In order to correct the measurement error, the flow rate value obtained by the detectors (12a and 12b) in a certain period and the powder flow rate signal 17 which is the measured value of the feed tank weighing device 2 shown in FIG. And a powder concentration correction calculation.
FIG. 6 shows a flowchart of the powder concentration correction unit. When the powder concentration correction processing is started 28 by manual operation by a human or automatically at a predetermined time interval, a predetermined time (T) and flow rate are set for both the feed tank weighing device 2 and the electrostatic capacity type powder flow meter. The values are integrated (29 and 30). In addition, the integration of the flow rate value of the capacitance type powder flow meter is made to coincide with the measurement value by the weighing instrument by using the sum of all the branch pipes. After the elapse of a predetermined time, the integrated values of the two are compared (31). If an error of a predetermined value or more has occurred, an alarm is displayed (32) and count correction calculation is performed. In the count correction calculation, the average blowing speed within T time is calculated from the integrated values obtained in 29 and 30 (33 and 34). Thereafter, at 35, a powder concentration correction coefficient α is obtained from the ratio between the two. Here, the powder concentration correction coefficient α is obtained by the ratio of both, as described above, there is a linear relationship between the detector output signal and the actual concentration as shown in FIG. This is because it has been found that when powders with different electric capacities are used, only the slope of the linear equation changes.

Thereafter, as shown in FIG. 2, the output result of the powder concentration correction unit 16 and the measurement result of the flow rate of the flow rate calculation unit 18 are multiplied by a multiplier 19, and the powder flow rate output unit 20 calculates the powder flow rate.
The powder flow rate mask processing unit 21 performs a mask process for the powder flow rate. That is, in the powder blowing equipment of the blast furnace, the purge of the branch pipe is carried out by automatic operation (periodic) or manual operation for the purpose of preventing clogging of the pipe due to the powder of each branch pipe. First, the pipes are switched using the three-way valve 5 and the branch pipe purge line 6 in FIG. 1, and the branch pipes are cleaned by flowing only gas. At that time, as shown in 39 of FIG. 7, the powder flow rate does not become zero and the wrong powder flow rate is displayed due to the difference in the gas component and the humidity and the powder accumulated in a part of the piping. Further, even after the purge is completed and the powder blowing is restored to the normal state as in 40, the measured value may be disturbed while the powder flow returns to the normal state. Therefore, in 22 of FIG. 2, the powder flow rate mask processing unit 21 has a function of fetching a purge timing signal from the outside and forcibly setting the flow rate signal to zero during the purge.

A detailed signal flow chart of the powder flow rate mask processing unit is shown in FIG. When the purge occurs at 41, the powder flow rate is forcibly set to “0” during the 42 purge periods (Td time). If the external signal at this time is not purging and the powder flow rate at the flow meter installation position is cut off, the same measures can be taken. After the purge is completed (43), a predetermined period of time at 44 has a function of setting a predetermined powder flow rate (F) or a powder flow rate immediately before the start of the purge. Thereafter, after a lapse of a certain time (45), a process of switching the powder flow rate to the actually measured powder flow rate at 46 is performed.
Further, even when the branch pipe purge is performed during the period in which the flow rate correction of FIG. By setting the flow rate to a high value, accurate flow rate correction is realized even during purging. By using the above system, the powder flow rate is accurately measured in the powder blowing equipment of the blast furnace.

It is the schematic of the powder blowing equipment of the blast furnace to which this invention is applied. The figure is a top view of the distributor. 1 is a schematic configuration of a powder flow rate measurement system of the present invention. It is a schematic diagram of the output value fluctuation | variation by powder adhesion etc. It is a flowchart of the signal processing of a zero point adjustment part. It is a relationship figure of a detector output signal and the actual density of powder. It is a flowchart of the signal processing of a powder concentration correction | amendment part. It is a schematic diagram of the powder flow rate fluctuation | variation during a purge period. It is a flowchart of the signal processing of a powder flow rate mask process part.

Explanation of symbols

1: Feed tank (hopper tank)
2: Weighing scale for feed tank 3: Gas line for powder transfer 4: Distributor tank (distributor)
5: Three-way valve 6: Branch pipe purge line 7; Blower tuyere 8: Blast furnace main body 9: Capacitance type powder flow meter 10: Each branch pipe 11: Capacitance type powder flow meter body 12a: Detector 12b: Detection Device 13: Detector output signal 14: Zero point adjustment unit 15: Coefficient correction unit 16: Powder flow rate correction unit 17: Weighing value signal of feed tank 18 :: Flow rate calculation unit 19: Multiplier 20: Powder flow rate output unit 21 : Powder flow mask processing unit 22: Powder blowing stop signal 23: Powder blowing stop check 24: Confirmation of detector output signal 25: Comparison between detector output signal and predetermined absolute value D 26: Output Correction calculation 27: Alarm display 28: Start of powder flow rate correction

Claims (5)

In powder blowing equipment that blows powder through piping with carrier gas in plants such as blast furnaces and power plants,
A feed tank for storing powder equipped with a weigher, a carrier gas supply means, a distributor tank for storing a powder gas mixed gas of powder and carrier gas, and connecting the feed tank and the distributor tank A main pipe part, a single or a plurality of branch pipe parts for blowing the powder gas mixed gas in the distributor tank into the plant, a branch pipe purge line for purging the powder gas mixed gas from the branch pipe part, A powder blowing facility comprising a powder flow rate measuring system for measuring a body blowing amount, wherein the powder flow rate measuring system is a capacitance type powder flow meter attached to the branch pipe part. In addition, with respect to the output signal of the electrostatic capacity type powder flowmeter, the zero point adjustment unit for correcting the zero point of the powder flow rate, and the above-mentioned output due to powder type and concentration fluctuations. A powder blowing equipment comprising a powder concentration correction unit for correcting a fluctuation of a force signal. In addition to the electrostatic capacity powder flow meter, the zero point adjustment unit, and the powder concentration correction unit, the powder flow rate measurement system includes:
A flow rate calculation unit that calculates the flow rate of the powder gas mixed gas, a count correction unit that converts an output signal of the capacitance type powder flow meter into a powder flow rate, the flow rate calculation unit, and the powder concentration correction unit The powder flow rate output unit for calculating the powder flow rate from each output value of the above, and the powder for correcting fluctuations in the measured powder flow rate at the time of branch purge for the powder flow rate measurement value of the capacitance type powder flow meter The powder blowing equipment according to claim 1, comprising a body flow mask processing unit.   The zero-point adjusting unit is configured to operate the electrostatic capacity type powder flow meter normally with respect to the output signal value of the electrostatic capacity type powder flow meter, and the powder gas mixed gas is not in the branch pipe. The initial output signal value is measured in advance to be the initial value C, and when the subsequent blowing of powder is stopped, the output signal value is measured as A, and the absolute value of the difference between A and C exceeds a predetermined value. (AC) is obtained as a zero point correction value, and the output signal value A ′ of the capacitance type powder flow meter at the time of powder injection is corrected to (A ′ − (AC)). The powder blowing equipment according to claim 1 or 2, characterized in that.   The powder concentration correction unit includes a decrease amount of powder in the feed tank in a predetermined period T measured by a weighing device installed in the feed tank, and a powder blowing amount measured by each capacitance powder flow meter. The output signal value of the electrostatic capacitance type powder flowmeter is corrected by comparing the total sum of the integrated values in the predetermined period T of claim 1 to claim 3. The powder blowing equipment according to one item of the above. The powder flow rate mask processing unit forcibly masks the powder flow rate measurement value when the powder flow rate measurement value of the capacitance type powder flow meter is cleaned by flowing only the gas through the branch pipe. The powder according to any one of claims 2 to 4, wherein the powder is set to a value immediately before the start of gas cleaning or a predetermined flow rate when predetermined after gas cleaning is completed. Blowing equipment.

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