JP2000037610A - Method for shaking off powdery dust and filter element to be handled by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light filter element with good appearance and a method for shaking off powdery dust on the filter by which the dust on the filter can be shaken off with enhanced efficiency while the durability of the filter being maintained or increased. SOLUTION: This method for shaking off powdery dust is carried out by jetting pulsed jet air to an filter element with a bottomed cylindrical shape made of a resin fiber material by heat molding in the counter direction to powder dust collecting air flow and the duration of a pulse of the pulsed jet air is controlled to be 0.05-0.2 sec and a secondary peak of the jetted air pressure from the filter element attributed to the pulse is generated within a time range of 0.1-0.3 sec after primary peak generation. Moreover, the filter element is provided with one outer supporting member being wrapped around the whole circumference of the filter element to be a reinforcing member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter used in industrial dust collectors and separators employed in various plants, and more particularly to a filter element suitable for collecting fine particles and a method for removing dust from the filter element. .

[0002]

2. Description of the Related Art As is well known, steel, electric power, ceramics, metallurgy,
Dust is contained in high-temperature gas generated in various plants in the field of chemistry and the like.
There is a filter element formed into a bottomed cylindrical shape with a nonwoven fabric or felt made of resin fibers as disclosed in Japanese Patent No. 77321.

[0003] The bottomed cylindrical filter element is formed by thermoforming a material such as polyimide fiber, polyphenylene sulfide fiber, polyester fiber, polypropylene fiber or the like. Then, by connecting the internal passage of the filter element to a suction source, the dust-containing gas to be filtered is sucked, dust contained in the gas is collected on the outer surface of the filter, and clean gas is introduced into the internal passage. Obtainable. Then, in order to maintain the filtration capacity, it is necessary to remove dust collected on the outer surface of the filter, and pulse jet air in the direction opposite to the suction direction of the dust-containing gas is automatically generated at regular time intervals. By introducing,
"Backwashing" is implemented, which is a uniform and efficient removal of dust collected to a certain extent and solidified.

[0004] A further configuration of such a filter element is to reinforce the element wall itself in order to reduce the inward compressive force applied to the outer wall of the element due to the suction force of gas during filtration. , An internal support member is provided. Further, there is provided an external support member for suppressing the outward expansion force applied to the outer wall of the element to some extent due to the pulse jet air pressure at the time of the back washing. With these configurations, the pressure resistance of the filter element against compression and expansion is increased, and the rigidity is increased, so that the pulse jet air pressure is used as it is as the pressure for blowing off the dust, thereby achieving efficient removal.

[0005]

However, in the above fired filter element, the thickness of the element wall is limited due to the setting of the pressure loss in filtration suction, and the strength of the entire element is increased only by the thickness. There is a limit. Therefore, in order to provide strength that can withstand pulse jet backwashing, within a range that does not affect filtration efficiency,
Strength reinforcement by external supports is required. In particular, higher strength is achieved by using a plurality of external supports. Moreover, in order to efficiently wipe off, it is general that the rigidity is high, a plurality of external support members as described above are provided, and the pulse jet air pressure is increased after increasing the rigidity, or They are trying to increase the pulse time and increase the efficiency of the removal.

[0006] However, if the pulse time is short, there is a problem that the dust once blown is re-collected to the filter element even if the pulse jet air pressure is increased as high rigidity. Of 1
There is a problem of wasting compressed air which is one of the factors. Further, such a plurality of external supports are made of a metal such as iron, aluminum or titanium. In the case of a large-sized cleaning device used in a factory or the like, the ratio of the external supports to the total weight of the filter is 30%. Some of them are also close, so in the filter mounting work, the number of parts increases the number of work processes, resulting in an increase in the number of parts, an increase in cost,
Furthermore, there were problems such as poor appearance.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and can realize more efficient dust removal while maintaining or increasing the durability of the filter element.
An object of the present invention is to provide a filter element that is lightweight and has a good appearance, and a method for removing dust from the filter element.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to inject pulse jet air in a direction opposite to a dust collecting gas flow to a bottomed cylindrical filter element formed by thermoforming a resin fiber material. Dusting method, wherein the time of one pulse of pulse jet air is 0.05 to 0.2 sec.
After the primary peak of the air pressure ejected from the filter element surface caused by this pulse, a time range of 0.1
This is achieved by a method for dusting out filter elements, characterized in that a secondary peak is generated in ~ 0.3 sec. Further, the above object of the present invention is a filter element in which the above dust removing method is performed,
A filter comprising one or two external support members serving as a frame-shaped reinforcing member disposed in contact with the outer periphery of a bottomed cylindrical filter element formed by thermoforming a resin fiber material. Achieved by elements.

That is, as a result of intensive studies, the inventor of the present invention has found that dust which injects pulse jet air in a direction opposite to a dust collecting gas flow to a bottomed cylindrical filter element formed by thermoforming a resin fiber material. It has been found that it is effective to generate a secondary peak after the primary peak of the air pressure ejected from the filter element surface due to the pulse jet air at the time of backwashing in the cleaning method. Then, as described above, the time of one pulse of the pulse jet air for the filter element is set to 0.05 to 0.2 msec, and the time range including the secondary peak in the backflow air exhaust pressure is set to 0.1 to 0.2 msec. By setting an appropriate length of 0.3 sec, the blown-out dust drops down before the re-suction of the filter element starts. Thus, the time range is 0.1-0.3sec
If the length is about the same, the removal can be performed efficiently without lowering the filtration efficiency.

Further, in the filter element in which such a removing method is executed, the maximum air pressure of the primary peak of the backflow air exhaust pressure is reduced to the secondary peak by using one or two external support members. Regardless, the dust that has been blown out does not fly to the next filter element and be collected again by an excessively high pressure. Since the number of external support members is one or two, the weight of the entire filter can be significantly reduced, and the assembling workability can be improved.

As the filter element to which the method of the present invention is applied, a polyimide fiber molded body described in JP-A-7-109664 is mainly used. However, any filter element which is heat-resistant and self-supporting and requires an external support material can be used. If applicable.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for removing dust from a filter element according to the present invention will be described below in detail with reference to the drawings. The filter element according to the present invention is not limited by the following description and drawings. FIG. 1 is a partial longitudinal sectional view of a dust collecting device using a filter element according to the present invention, and FIG. 2 is a perspective view in which an external support is attached to the filter element shown in FIG.

The trapping device 1 has a sealed casing 2 having a substantially rectangular shape, and the inside thereof is divided into a trapping chamber 4 at a lower part and a clean air chamber 5 at an upper part by an upper top plate 3 which is a partition wall. A dust-containing air supply port 6 communicating with the lower collecting chamber 4 is provided on the middle side of the casing 2. A clean air outlet 7 communicating with the clean air chamber 5 is provided at an upper portion of the casing 2. Are attached to the lower surface of the upper top plate 3 at predetermined intervals. The filter element 8 has a large diameter portion 9 formed at the upper end, and is attached to the upper top plate 3.

The dust-containing air supplied from the supply port 6 into the collection chamber 4 of the casing 2 passes through the filter element of the filter element 8 which is hollow and has, for example, a corrugated or bellows-shaped cross section, and flows inward. . At this time, the dust adheres and accumulates on the surface of the filter element 8 and is collected, and the clean air flowing into the filter element 8 enters the clean air chamber 5 in the upper part of the casing 2 through the internal passage and is discharged therefrom. It is guided to a predetermined place from the exit 7.

FIG. 2 is a perspective view showing the structure of the filter element 8, in which a hollow chamber 8a is formed as can be seen from the cross section 8d. They are further cylindrical with a bottom, as can be seen from the perspective view of the filter element 8 shown in FIG. The cross section of the dust adhering surface 8b has a corrugated or bellows shape, and is set so that the adhering surface area is as large as possible. An external support member 20 is attached so as to cross the waveform of the filter element 8 and to make a round around the filter element 8 at a substantially central portion. The external support member 20 is preferably in a frame shape in contact with the outer periphery of the filter element 8, and is preferably configured to reinforce the filter element 8 to increase the pressure resistance and rigidity.
Although a shape following the waveform shape of the filter element 8 is also possible, it is preferable that the filter element 8 is simply a rectangular frame surrounding the waveform element and the waveform peak portion is sandwiched from the outside. In this case, since the shape is simple,
The manufacturing cost of the external support can be reduced. As a material of the external support member 20, an aluminum material, an iron material, or the like can be used, but a corrosion-resistant material is preferable in order to cope with various kinds of gases to be processed.

Returning to FIG. 1, the filter elements 8, 8,... Are sequentially backwashed with pulse jet air at regular time intervals during the dust adsorption, and the filter elements 8, 8,. Remove dust adhering and accumulating on the surface. That is, as shown in FIG. 1, injection pipes 13 for backwashing are arranged above the upper top plate 3,
Each of the injection pipes 13, 13,... Is connected to an air generation source via a backwash valve (corresponding to each of the injection pipes 13) not shown. Then, the backwash valves are sequentially opened and closed at regular intervals by a timer control or the like, and pulse air for backwash is injected by the corresponding injection pipe 13 and injection nozzle 14. As a result, the pulse air flows backward from the inside to the outside of each filter element 8, and dust adhering and accumulating on the surface of the filter element 8 is removed. The dust that has been blown off falls into the hopper 15 below the casing 2 and is collected.

Next, the operation of the payoff method of the present invention will be described below. FIG. 3 is a graph schematically showing a temporal change of the internal pressure of the element at the time of backwashing according to the present invention for each number of external support members. Here, in FIG. 1 and FIG. 2, the number of the external support members of the filter element is one, but the backwashing by the pressure change shown in FIG. 3 is also effective for a plurality of the filter elements.

As a detailed operation of the wiping method of the present invention, first, a cake-like collected matter in which dust adhering to the filter element surface is collected is peeled off by the impact of the primary peak. The collected material falls along the filter element surface, and during that time, by holding the inside of the filter element at a positive pressure (plus pressure) at the secondary peak, the suction action is suppressed until the separated collected material falls, This prevents the collected matter from re-adhering to the filter element. That is, since the possibility of reattachment of the collected matter remains, the primary peak alone cannot complete the sweeping action. Moreover, the larger the absolute value of the primary peak, the farther the debris is trapped, and the more the primary peak is sprayed on the adjacent filter element. Therefore, it is important to maintain the inside of the filter element at a positive pressure (plus pressure) by using the secondary peak.

The condition that the primary peak can completely separate the trapped matter and falls so as not to spray it on the adjacent filter element, and further does not affect the collection efficiency of the dust trapping apparatus. The time of one pulse of the pulse jet air is set to 0.05 to 0.2 sec so that the secondary peak is generated within a time range of 0.1 to 0.3 sec after the generation of the primary peak. Therefore, with such a removing method, the removing can be performed efficiently without lowering the filtration efficiency.

Further, in such a condition setting, as shown in FIG. 3, the primary peak is made variable by the number of external support members,
The pressure value can be increased as the number of external support members increases. FIG. 4 is a graph that makes it easier to understand the change in the values of the primary peak and the secondary peak with respect to the number of the external support members. The change in the primary peak is proportional to the change in the number of the external support members. The value can be kept almost constant without being affected by the number of support members.

Next, as shown in FIGS. 3 and 4, the number of filter elements on which the above-described clearing method is executed can be adjusted to a plurality of filter elements. It is preferable that the number of external support members of the filter element is one. By using a single external support in this manner, the maximum air pressure at the primary peak of the backflow air exhaust pressure can be reduced regardless of the secondary peak, and the dust that has been blown once becomes too high due to unnecessarily high pressure. It does not occur that the filter element jumps to the filter element and is collected again. Also, energy consumption can be suppressed by reducing the pressure. And since there is only one external support member, the weight of the entire filter can be significantly reduced, and the workability in assembling can be improved.

FIG. 5 is a graph showing the change over time of the actual pressure measurement in the backwashing of the present invention. As basic conditions, while constantly filtering at a filtration wind speed of 1.0 m / min, backwash pulse jet air pressure of 5 kgf / cm ² G, pulse time of 0.1
Perform backwash in sec. And the number of external support materials is 5,
In the case of three, two, one, and zero, the pressure change pattern at one location in the center of the filter element is shown. As can be seen from FIG. 5, as a feature of the pressure change pattern of the present invention, two large peaks can be formed in addition to the shared portion for 0.02 sec at the beginning of the pulse jet air blowing. The one at the time of rising is the primary peak, and the one following it is the secondary peak. Among them, 0
Only in the case of a book there is no primary or secondary peak.

Among these, the maximum ultimate pressure decreases as the number of external supports decreases, and there is a difference of about 100 mmAq between 5 and 1 pieces, and a similar difference between 1 piece and 0 pieces. is there. In particular, when the number of the external support members is 0, the maximum attainable pressure is increased only up to about 70 mmAq, so that dust cannot be completely removed. On the other hand, when the number of external support members is one, the pressure is about 150 mmAq, which is a pressure at which a sufficient wiping performance can be exhibited. With such a high pressure, the service life of the filter element can be extended by an amount corresponding to the lower pressure as compared with the case where the number of external support members is five.

The method for measuring the pressure in the filter element used in the present invention will be described below. FIG. 6 shows an outline of this pressure measurement. The dimensions of the filter element in FIG. 6 are height × width: 1500 × 1000 mm,
A pressure tap 30 was attached to one surface of one of the filter elements, and the filter element was installed in a load tester 50. The mounting position and the number of the pressure taps 30 are arbitrary. In this case, it is a comparison of measured values for the difference in the number of external support members, and is set at one location in the center of the filter element.

The pressure tap 30 is inserted up to the internal space of the filter element so that the internal pressure can be derived. Pressure inside filter element is pressure tap 3
From 0 is transmitted to the pressure transducer 52 by the pressure transmission tube 32. The pressure converter 52 converts the pressure into an analog voltage signal, and the signal is sent to a high-speed data acquisition system 54 where it is converted into a digital signal.
Stored in 0. As the measurement conditions, the filtration wind speed was 1 m /
min (room temperature), backwash pulse jet air pressure is 4 ~
It was 5 kgf / cm ² G. Since the outside of the filter element is open and at atmospheric pressure, the static pressure inside the filter element is equal to the pressure loss of the element. Pulse control device 58
Controls the supply of the pulse jet air from the compressed air tank 40 to the backwashing injection pipe 13 by opening and closing the electromagnetic valve 41 with an AC voltage signal of 100 V or 200 V. This voltage signal is transformed into a voltage of 1 V or less by the AC converter 56, sent to the high-speed data acquisition system 54, and used as a trigger (trigger) for starting data acquisition.

[0026]

According to the constitution of the present invention, the time of one pulse of the pulse jet air at the time of back washing is set to 0.05 to 0.2 msec,
The time range in which the secondary peak is included in the backflow air exhaust pressure after the primary peak of the air pressure ejected from the filter element surface due to this is set to an appropriate length of 0.1 to 0.3 sec. This allows the blown-off dust to drop to the hopper before the re-suction of the filter element starts, so that the dust can be efficiently removed without lowering the filtration efficiency. In addition, by using a single external support member, the maximum air pressure at the primary peak of the backflow air exhaust pressure can be reduced regardless of the secondary peak, and the dust that has been blown once becomes too high due to excessive high pressure. It does not occur that it jumps to the filter element and is collected again. And since only one external support member is used, the weight of the entire filter can be significantly reduced, and the workability of assembling can be improved. As described above, an object of the present invention is to provide a light-weight and good-looking filter element capable of realizing more efficient dust removal while maintaining or increasing the durability of the filter element, and a method of removing the dust.

[Brief description of the drawings]

FIG. 1 is a partial vertical sectional view of a dust collecting device using a filter element according to the present invention.

FIG. 2 is a perspective view in which an external support is attached to the filter element 8 shown in FIG.

FIG. 3 is a diagram schematically showing a temporal change of an internal pressure of an element when the dust removing method of the present invention is executed, for each number of external support members.

FIG. 4 is a diagram that makes it easier to understand a change in values of a primary peak and a secondary peak with respect to the number of external support members.

FIG. 5 is a diagram showing a change with time in actual pressure measurement of backwashing according to the present invention.

FIG. 6 is a diagram schematically illustrating the pressure measurement performed in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Collection device 2 Casing 3 Upper top plate (partition wall) 4 Collection room 5 Clean air room 8 Filter element 8a Hollow room 8b Surface 8d Cross section 13 Injection pipe 15 Hopper 20 External support material 30 Pressure tap 40 Compressed air tank 50 Load Tester

Continued on the front page F term (reference) 4D019 AA01 BA13 BB03 BB04 BC12 CA04 CB06 CB09 CB10 4D058 JA06 JB14 JB25 JB41 KA06 KA23 KA25 KB05 MA15 MA25 MA54 PA04 SA20

Claims (2)

[Claims] 1. A dust removing method for injecting pulse jet air in a direction opposite to a dust collecting gas flow to a bottomed cylindrical filter element obtained by thermoforming a resin fiber material, wherein the pulse Time of one pulse of jet air is 0.05 ~
0.2 sec, and a secondary peak is generated within a time range of 0.1 to 0.3 sec after a primary peak of air pressure ejected from the filter element surface caused by this pulse is generated. How to pay off. 2. A filter element for carrying out the dust removing method according to claim 1, wherein the filter element is disposed in contact with the outer periphery of a bottomed cylindrical filter element formed by thermoforming a resin fiber material. A filter element comprising one or two external support members serving as a frame-shaped reinforcing member.