JP4101922B2 - Method for determining filter cloth abnormality and estimating filter cloth deterioration in dry gas cleaning equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a filter cloth abnormality determination and a filter cloth deterioration estimation method for a dry gas cleaning facility.
[0002]
[Prior art]
In general, a dry gas cleaning facility is provided for recovering gas energy in the high temperature reactor. For example, an outline of the facility for recovering the reaction gas in the blast furnace is gas from the top of the blast furnace 1 as shown in FIG. First, it is connected to a dust catch 2 which is a first-stage dust collector through the ascending pipe 1a and the descending pipe 1b. Next, the dust catcher 2 is divided into two systems, a dry dust collection system 3 and a wet dust collection system 4, and dry gas cleaning facilities 3 a and 3 b such as bag filters are connected to the dry system 3. Further, the wet dust collection system 4 is connected with water spray type wet dust collection devices 4a and 4b. The two systems are joined downstream, and further, a furnace top generator 5 is provided downstream as an energy recovery facility. Yes.
[0003]
As described above, a bag filter is used as a dry gas cleaning facility, and there is a screen type filter, but most of the filter is a cylindrical container bag type. The diameter is about 10 to 50 cm, and a thing with a length of several m or less is suspended vertically to allow airflow to pass inward and to deposit dust on the inside. Moreover, this cylindrical container has a thing which closes an upper part and a dust airflow enters from the downward | lower direction, and a thing entered from the upper part.
In any case, when the filtered accumulated dust is removed, the inside of the cylindrical container falls downward due to gravity and accumulates in the dust collecting chamber.
If the accumulated dust is not sufficiently removed, the pressure loss increases, the power cost increases, or the amount of processing gas decreases, making it difficult to use.
[0004]
The measurement method of the amount of dust on the outlet side of dry gas cleaning equipment is a continuous dust concentration meter that detects the frictional charge generated by absorbing the gas at a constant flow rate and colliding with the exciter. Measurement method based on dust concentration measurement method “JISZ 8808” for measuring concentration based on dust mass and measurement gas amount adhering to the filter, and passing the gas through the filter to check whether there is any abnormality due to color density A simple filter check method for judging is mentioned.
[0005]
As another device for detecting the breakage of the filter cloth, a detector for detecting the air permeability and / or suction sound of the filter cloth is arranged close to the surface of the filter cloth, and the detector is attached to the filter cloth surface. Japanese Patent Application Laid-Open No. 60-110316 discloses an apparatus for detecting breakage of a filter cloth based on a change in ventilation sound by relatively moving. As another method, when detecting breakage of a bag filter equipped with a pulse air type dust removal mechanism, a pipe lined along the filter cloth and purged with air is used as a gas suction pipe, and suction is performed from this gas suction pipe. Japanese Laid-Open Patent Publication No. 7-328363 discloses a method for identifying a broken portion of a filter cloth by measuring the amount of dust.
[0006]
[Problems to be solved by the invention]
Since the conventional filter cloth checking method is configured as described above, the following problems exist. In other words, in order to maintain the performance of the dust collector, it is necessary to measure the dust concentration on the outlet side of the dust collector regularly. However, as a reliable method, a suction pipe, which is a measuring device, is connected to the pipeline of dust or the like to be measured directly. There is a method “JISZ8808 (1986)” for measuring dust concentration in exhaust gas, which is attached to determine the amount of dust per unit in exhaust gas.
However, this method stipulates the measurement method under a general environment. For example, in a blast furnace top gas cleaning facility that has passed through a high-temperature gas cleaning facility in a dry type, sufficient caution is required for measurement. .
This is due to the gas component and temperature, and the gas passing through the cleaning equipment is in a high temperature state, but since the measurement instrument is inserted into the pipe and measured, there is a difference between the temperature of the measurement instrument and the gas temperature, The dust collecting filter cloth attached to the measuring instrument is in a low temperature state at the time of measurement, and compounds such as ammonium chloride and iron chloride are precipitated due to a decrease in temperature.
In this method of measuring the weight of dust adhered to the filter cloth, naturally this chloride is also measured as dust, so measurement without reducing the temperature is necessary, and work such as preheating is required (that is, measurement) The first measurement when the temperature of the instrument is low is unreliable).
[0007]
In addition, in order to measure dust adhering to the filter cloth, when measuring low-concentration dust, it is necessary to collect an amount of dust in consideration of measurement errors, and a minimum of 30 minutes / time, ideally 60 minutes. It is necessary to spend at least 3 times / time, and this measurement needs to be performed at least 3 times.
Furthermore, since it is necessary to dry the filter cloth, it took 5 to 6 hours at least from the measurement until the result was obtained.
Therefore, the present method, which needs to have expertise and skills for measurement, is difficult to be performed with high frequency, and there is a method called simple filter check as another method.
In this method, gas is passed through the filter cloth for a certain period of time at a substantially constant flow rate, and the dust collector's abnormality (breaking in the case of the filter cloth method) is detected by the darkness of the color of the filter cloth. The judgment relies on human vision, and an attempt was made to measure the lightness of the filter cloth as a quantitative evaluation method.
[0008]
However, even in this method, the problem of precipitation of iron chloride is the same as that of JISZ8808 (type I), and the following problem has occurred.
The blast furnace gas itself basically does not contain oxygen, but the sampling pipe for simple filter check is exposed to the atmosphere during non-measurement, so a large amount of iron oxide is deposited on the inner surface of the pipe. This iron oxide is gradually mixed and adheres to the filter cloth.
Ammonium chloride is colorless and is not reflected in color, and is superior to the gravimetric method in this respect. However, if the influence of iron oxide and iron chloride is not removed, the filter cloth brightness alone can be used as a method for judging the dust collector abnormality. It turned out that it cannot be used.
[0009]
In FIG. 4, the gas that has passed through the main filter cloth 11 in a conventional dry gas cleaning facility is branched from the gas pipe 12 and a branch pipe 13 is provided via a valve 15 for simple filter check. A test filter cloth 14 for collecting dust flowing in the pipe was provided, and the gas from the gas pipe 12 was passed through the filter cloth 14 to adhere the dust. The lightness of the filter cloth 14 before installation measured with a lightness meter is L1 * (Elwan Star), the measurement value of the filter cloth 14 with dust measured with a lightness meter is L2 *, and the difference in brightness and frequency before and after use are A histogram is shown in FIG.
In FIG. 3, it can be seen that the filter cloth 14 tends to be normal or abnormal, but the value that makes the filter cloth 14 abnormal is also given to the larger value of the brightness difference, and it has been found that the filter cloth 14 is not a sufficient standard.
[0010]
Therefore, it was clarified that the dust passing through the gas pipe cannot be managed only by the difference in brightness between the new filter cloth and the filter cloth after use with a lightness meter. This is because the brightness meter is affected by the components contained in the gas that has passed through the gas cleaning facility as described above.
[0011]
The present invention has been made to solve the above-described problems. In particular, the gas passing through the gas cleaning equipment is measured with a color difference meter, and the lightness difference is color-corrected to correct the brightness of the filter cloth of the equipment. It is an object of the present invention to provide a method for estimating the filter cloth abnormality and the filter cloth deterioration of a dry gas cleaning facility that makes the determination of normality / abnormality simple.
[0012]
[Means for Solving the Problems]
According to the dry gas cleaning equipment filter cloth judging method according to the present invention, a branch pipe is provided in the gas pipe downstream of the main filter cloth of the dry gas cleaning equipment, and a filter cloth for collecting dust is provided in the branch pipe. The dust in the gas passing through the gas pipe is attached to the filter cloth, and the dust attached to the filter cloth is measured for red color and lightness with a color difference meter, and further the dry gas cleaning according to the present invention The method for estimating the deterioration of the filter cloth of the equipment is to provide a branch pipe in the gas pipe on the downstream side of the main filter cloth of the dry gas cleaning equipment, and to provide a filter cloth for collecting dust in the branch pipe. The dust in the gas passing through the filter is attached to the filter cloth, the filter cloth is measured for the lightness of the filter cloth with a color difference meter, and from the relative dust concentration ratio (n) of the following equation (1), This is a method for estimating the deterioration of the filter cloth.
n = [ln (ΔL * / L1 * + 1) −β · a *] / γXo (1)
ΔL * = L2 * -L1 *
here,
L1 *; lightness of filter cloth before dust adhesion L2 *; lightness of filter cloth after dust adhesion a *; redness of filter cloth after dust adhesion β; color component constant Xo; allowable dust concentration through main filter cloth (mg / Nm ³⁾ )
γ: Dust concentration constant n; Relative dust concentration ratio
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a method for determining filter cloth abnormality determination and filter cloth deterioration of a dry gas cleaning facility according to the present invention will be described with reference to the drawings.
Since the configuration shown in FIG. 4 is used as the apparatus used in the present invention, the configuration shown in FIG. 4 will be described here again. That is, the gas that has passed through the filter cloth 11 of the dry gas cleaning facility in FIG. 4 is branched from the gas pipe 12 to provide a branch pipe 13 for simple filter check, and dust flowing in the pipe is collected in the middle of the pipe. A test filter cloth 14 is provided, and the gas from the gas pipe 12 is caused to flow through the filter cloth 14 through the valve 15 to adhere dust. In the test, after measuring the brightness Elster (L1 *) of the new filter cloth 14 before installation, the filter cloth 14 is installed, the valve 15 of the branch line 13 is opened, and gas is supplied to the branch line 13 for 5 minutes. Washed away. Thereafter, the filter cloth 14 was removed, and the red aster (a *) and lightness elster (L2 *) of the filter cloth 14 with dust mainly composed of iron oxide were measured with a color difference meter (not shown).
In addition, the brightness (L *: Elster) and red (a *: Aster) referred to in the present invention refer to L * and a * when expressed in the CIE 1976 L * a * b * color system.
The brightness L * of this color difference meter has a maximum value of 100 on the bright side and a minimum value of 0 on the dark side. However, L * was 97 on a new filter cloth 14 with no dust attached. It was corrected to 97.
When the dust-attached filter cloth 14 is measured with a color difference meter and the relationship between the a * value (Aster) representing red and the brightness difference ΔL * before and after dust attachment is shown in FIG. It can be seen that the relationship between the red color and the brightness is clear, and the normality / abnormality of the filter cloth 14 can be managed from this relationship. That is, as shown in FIG. 2, if the filter cloth 14 is continuously measured with a color difference meter at -ΔL * and a * coordinates, the normal time and the abnormal time are stratified. An abnormality can be determined when L * is a large value.
[0014]
Further, when the boundary F between the normal value and the abnormal value is created as shown in FIG. 1 and managed by the filter cloth 14 shown in FIG. 4, the abnormality can be determined using the relative dust concentration ratio n.
That is, the ratio of the relative dust concentration to the main filter cloth passage allowable dust concentration (corresponding to the normal dust concentration) is measured with a dust color difference meter attached to the filter cloth 14 before and after use measured in the test branch pipe 13. When represented by (n), it becomes one set.
n = [ln (ΔL * / L1 * + 1) −β · a *] / γXo (1)
ΔL * = L2 * -L1 *
here,
L1 *; lightness of filter cloth before dust adhesion L2 *; lightness of filter cloth after dust adhesion a *; redness of filter cloth after dust adhesion β; color component constant Xo; allowable dust concentration through main filter cloth (mg / Nm ³⁾ )
γ: Dust concentration constant n; Relative dust concentration ratio Xo is the allowable dust concentration through the main filter cloth (mg / Nm ³ ). Use the dust concentration when the filter cloth is normal, or the specification value when designing the dust collector May be used, and a normal reference condition may be used. The red aster a * is a measured numerical value of 0 to 100, the color component constant β <0, and the dust concentration constant γ <0.
Thus, when the measurement result is expressed in terms of relative dust concentration ratio n using Formula 1, n = 1 in the normal state, and as n> 1 is an abnormal value and n is larger, the deterioration of the main filter cloth becomes more remarkable. Can be estimated quantitatively.
FIG. 2 shows the estimation result of the present invention obtained by calculating back one equation. Here, the + mark is a value when the relative dust density ratio n is 1 based on the normal dust density, and the x mark is a numerical value when n = 5 (corresponding to 5 times normal). ing. From this result, it can be seen that normality / abnormality can be reliably stratified by using the above-mentioned formula 1, and the deterioration degree of the main filter cloth can be estimated by the magnitude of n.
[0015]
FIG. 1 shows the relative dust concentration and frequency in FIG. 1 described above. The filter cloth 14 of the gas cleaning facility can be managed by managing the relative dust concentration.
[0016]
【The invention's effect】
Since the method for estimating the filter cloth abnormality and the filter cloth deterioration of the dry gas cleaning equipment according to the present invention is configured as described above, the following effects can be obtained. That is, by carrying out the invention of claim 1, it is possible to easily determine the abnormality of the filter cloth by measuring the filter cloth with a color difference meter and looking at the red color and the brightness.
By carrying out the invention of claim 2, it is possible to easily estimate the deterioration of the filter cloth provided in the gas cleaning facility based on the relative dust concentration ratio.
[Brief description of the drawings]
FIG. 1 is a histogram of lightness when a filter cloth is normal / abnormal when a filter cloth abnormality is determined according to the present invention.
FIG. 2 is a characteristic diagram showing a relationship between an aster measured by a color difference meter and a brightness difference.
FIG. 3 is a characteristic diagram showing the relationship between relative dust concentration ratio and frequency.
FIG. 4 is a configuration of a branch pipe measured by a simple filter check.
FIG. 5 is a schematic configuration diagram of gas energy recovery equipment in a blast furnace.
[Explanation of symbols]
1 Blast Furnace 2 Dust Catcher 3 Dry Dust Collection System 4 Wet Dust Collection System 5 Furnace Top Generator 11 Main Filter Cloth 12 Gas Pipe 13 Branch Pipe 14 Filter Cloth 15 Valve

Claims (2)

A branch pipe (13) is provided in the gas pipe (12) on the downstream side of the main filter cloth (11) of the dry gas cleaning equipment, and a filter cloth (14) for collecting dust is provided in the branch pipe (13). The dust in the gas passing through the gas pipe (12) is attached to the filter cloth (14), and the dust attached to the filter cloth (14) is red (a *) and brightness ( L *) is measured for a filter cloth abnormality in a dry gas cleaning facility. A branch pipe (13) is provided in the gas pipe (12) downstream of the main filter cloth (11) of the dry gas cleaning equipment, and a filter cloth (14) for collecting dust is provided in the branch pipe (13). The dust in the gas passing through the gas pipe (12) is attached to the filter cloth (14), and the lightness (L *) of the filter cloth (14) is attached to the filter cloth (14) with a color difference meter. And red (a *), and the deterioration of the filter cloth (14) of the gas cleaning equipment is estimated from the relative dust concentration ratio (n) of the following equation (1): A method of estimating degradation.
n = [ln (ΔL * / L1 * + 1) −β · a *] / γXo (1)
ΔL * = L2 * -L1 *
here,
L1 *; lightness of filter cloth before dust adhesion L2 *; lightness of filter cloth after dust adhesion a *; redness of filter cloth after dust adhesion β; color component constant Xo; allowable dust concentration through main filter cloth (mg / Nm ³⁾ )
γ: Dust concentration constant n: Relative dust concentration ratio

Images