JP4233024B2 - Pulse backwash device for ceramic filter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulse backwashing device for a ceramic filter used by being incorporated in a dust collector for treating high-temperature exhaust gas emitted from an incinerator or the like of radioactive miscellaneous solid waste.
[0002]
[Prior art]
[Patent Document 1]
Japanese Examined Patent Publication No. 6-59374
As shown in Patent Document 1, a ceramic filter has been conventionally used in a dust collector for treating incinerator exhaust gas of radioactive miscellaneous solid waste. This ceramic filter C has a bottomed cylindrical shape called a candle type, and is suspended with a neck supported by a support plate 2 provided horizontally in the container 1 as shown in FIG. This support plate 2 is for partitioning the inside of the container 1 into an exhaust gas inflow chamber 3 and an upper cleaning chamber 4, and high temperature exhaust gas enters the exhaust gas inflow chamber 3 from the exhaust gas inlet 5 at the lower part of the container, and passes through the ceramic filter. It is filtered through the C porous wall. Then, the clean gas is discharged from the clean gas outlet 6 at the top of the container 1.
[0004]
If such an operation is continued, the porous wall surface of the ceramic filter C is gradually clogged with dust, and the filtration differential pressure increases. For this reason, conventionally, as shown in FIG. 4, a backwash pipe 7 is installed on the ceiling surface of the container 1, and compressed air is back-blowed into the clean chamber 4 from the backwash pipe 7. All the clogging substances are removed. However, such a batch backwashing method requires the facility to be stopped and has a problem that a sufficient backwashing effect cannot be obtained.
[0005]
In view of this, the present inventors have arranged a large number of backwash nozzles 8 with their tips opposed to one or several ceramic filters C as shown in FIG. A pulse backwashing system has been developed in which compressed air is sequentially supplied to each backwashing nozzle 8 in a pulsed manner. For pulse backwashing, a straight solenoid valve 9 capable of opening and closing the valve at a high speed of 0.05 seconds or less is used. According to this method, backwashing can be performed sequentially while the operation of the facility is continued. Such a backwash nozzle 8 is also disclosed in Patent Document 1.
[0006]
However, when the ceramic filter C subjected to the pulse back washing is observed in detail, the clogging substance is sufficiently removed in the lower part of the ceramic filter C having a total length of 1500 mm, but the removal effect is obtained in the upper part. It turned out to be insufficient. For this reason, when a pressure sensor was attached and the pressure on the surface of the ceramic filter C during backwashing was measured, it was confirmed that the average pressure during backwashing was only 2.4 kPa.
[0007]
Thus, when compressed air is blown as a pulse jet from the mouth of the bottomed cylindrical ceramic filter C, it is inevitable that the pressure in the lower part is higher than the upper part. However, in order to enhance the backwashing effect and operate without problems in actual equipment, it is desirable that the average surface pressure during backwashing of the ceramic filter C be 9.8 kPa or more.
[0008]
In order to easily achieve this object, the original pressure of the compressed air for backwashing may be increased from the current 600 kPa. However, if the original pressure of the compressed air for backwashing is increased in this way, the internal pressure of the container 1 increases during backwashing, and the principle of equipment that always performs negative pressure operation to prevent leakage of radioactive substances to the outside is impaired. It will be. Therefore, it is necessary to increase the backwash pressure of the ceramic filter without increasing the original pressure of the compressed air for backwashing.
[0009]
[Problems to be solved by the invention]
The present invention solves the above-mentioned conventional problems, and can perform pulse backwashing that can be sequentially backwashed while the operation of the equipment is continued, and without increasing the original pressure of the compressed air for backwashing. The present invention has been made to provide a pulse backwashing device for a ceramic filter capable of providing a sufficient backwashing pressure over the entire length of the ceramic filter.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a pulse backwashing device for a plurality of ceramic filters whose necks are supported by a support plate in a container, the tip of which is one or several ceramic filters. A number of backwash nozzles opposed to each other are arranged on the upper part of the support plate with a distance between the tip of the ceramic filter and the upper end of the ceramic filter of 20 to 40 mm, and pipes connected to the bases of the backwash nozzles are arranged on the container ceiling surface. It is penetrated and drawn horizontally to the outer periphery of the container, and is connected to the header on the outer periphery of the container through an angle type electromagnetic valve having a Cv value of 80 or more as a flow rate count of the valve .
[0011]
The present invention is characterized in that a pipe connected to the base of each backwash nozzle passes through the top surface of the container, is drawn horizontally to the outer periphery of the container, and is connected to a header on the outer periphery of the container via an angle type electromagnetic valve. As described below, the angle type solenoid valve is different from a normal solenoid valve in that an angle such as a right angle is formed between the inlet flow path and the outlet flow path of the compressed air, and a valve seat is provided at the intersection. ing. For this reason, a large amount of compressed air can flow to the backwash nozzle simultaneously with the start of the valve operation, and the average surface pressure during backwashing of the ceramic filter is not less than 9.8 kPa without increasing the original pressure of the compressed air for backwashing. Backwash pressure can be applied.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention are shown below.
FIG. 1 is a perspective view showing a preferred embodiment of the present invention, and FIG. 2 is a plan view thereof. The structure of the dust collector is the same as in the prior art. 1 is a container, 2 is a support plate that divides the inside into an exhaust gas inflow chamber 3 and an upper cleaning chamber 4, and a large number of candle-type ceramic filters C Is supported by the support plate 2 with the neck supported. In this embodiment, the number of ceramic filters C is about 100. The hot exhaust gas enters the exhaust gas inflow chamber 3 from the exhaust gas inlet 5 at the bottom of the container and is filtered by the porous wall surface of the ceramic filter C. The clean gas is discharged from the clean gas outlet 6 at the top of the container 1.
[0013]
A large number of backwash nozzles 8 with their tips opposed to one or several ceramic filters C are arranged on the upper side of the support plate 2. In this embodiment, the backwash nozzle 8 has a structure capable of backwashing four ceramic filters C at the same time, but the number can be increased up to about ten. A pipe 10 connected to the base of each backwash nozzle 8 penetrates the container ceiling surface 11 and is drawn horizontally to the outer periphery of the container. A ring-shaped header pipe 19 is arranged on the outer periphery of the container, and angle type electromagnetic valves 13 are arranged at the upper ends of the vertical pipes 12 extending from the header pipe 19. The pipe 10 is connected to the header pipe 19 on the outer periphery of the container via these angle type electromagnetic valves 13. The angle type solenoid valve 13 is sequentially opened by a control device (not shown), and the compressed air in the header pipe 19 is sequentially supplied to each backwash nozzle 8 for about 2 seconds to perform pulse backwashing.
[0014]
FIG. 3 is a conceptual diagram in which the angle type electromagnetic valve 13 is compared with the conventional straight type electromagnetic valve 9. In either case, a disk 15 driven by a solenoid 14 is provided inside, and an opening / closing operation is performed by bringing the disk 15 into and out of contact with the valve seat 16. However, in the straight type electromagnetic valve 9 in which the compressed air inlet channel 17 and the outlet channel 18 are arranged on the same straight line, when the disk 15 is separated from the valve seat 16, the compressed air has a narrow channel indicated by an arrow. The angle type electromagnetic valve 13 in which the inlet channel 17 and the outlet channel 18 are orthogonal to each other while flowing in a complicated manner allows a large internal space of the valve, and the disk 15 is separated from the valve seat 16. The flow is simple.
[0015]
For this reason, according to the present invention, a large amount of compressed air can be supplied to the backwashing nozzle 8 at the moment when the angle type electromagnetic valve 13 is opened, and without increasing the original pressure of the backwashing compressed air, An average surface pressure at the time of backwashing can give a backwashing pressure of 9.8 kPa or more. The capability of the solenoid valve can be expressed by a Cv value that is a flow rate count of the valve. The Cv value is a value representing the flow rate of water in the unit of gal / min when the valve is fully opened and the pressure drop before and after the valve is 1 psi. In the present invention, it is preferable to use a Cv value of 80 or more. The Cv value of a 50A angle type solenoid valve is 80 or more, and the Cv value of an 80A angle type solenoid valve is 100 or more.
[0016]
The tip of the backwash nozzle 8 and the upper end of the ceramic filter C are not in close contact with each other, but are preferably installed with a distance of 20 to 40 mm. Thereby, the surrounding gas enters the inside of the ceramic filter C along with the backwashing air during backwashing, and the backwashing effect can be enhanced. Examples of the present invention are shown below.
[0017]
【Example】
Example 1
Using the test apparatus provided with the ceramic filter C shown in the embodiment, backwashing air having an original pressure of 600 kPa was pulse jetted for 2 seconds from four backwashing nozzles capable of backwashing at the same time. The amount of air is 10 to 15 liters, and the nozzle tip diameter is 20 mm. The angle type solenoid valve used had a size of 50A, the operation speed was 0.05 seconds or less, and the tip of the backwash nozzle and the top of the ceramic filter C were separated by 20 mm. As a result, the average surface pressure during backwashing of the ceramic filter C reached 14.2 kPa. When the tip of the backwash nozzle and the upper end of the ceramic filter C were separated by 40 mm, the average backwash pressure of the ceramic filter C reached 13.4 kPa, and an excellent backwash effect was obtained in all cases.
[0018]
(Example 2)
Using the same dust collector as in Example 1, air for backwashing with an original pressure of 600 kPa was pulse jetted for 2 seconds from 7 backwashing nozzles capable of backwashing at the same time. The amount of air is 30 to 36 liters, and the nozzle tip diameter is 23 mm. The angle type solenoid valve used had a size of 80 A, the operation speed was 0.05 seconds or less, and the tip of the backwash nozzle and the top of the ceramic filter C were separated by 40 mm. As a result, the average surface pressure during backwashing of the ceramic filter C reached 13.7 kPa, and an excellent backwashing effect was obtained.
[0019]
【The invention's effect】
As described above, according to the ceramic filter pulse backwashing device of the present invention, the ceramic filter can be backwashed sequentially while the operation of the dust collecting equipment is continued. Moreover, by improving the supply path of the compressed air for backwashing, the average surface pressure during backwashing of the ceramic filter is given a backwash pressure of 9.8 kPa or more without increasing the original pressure, and an excellent backwashing effect is obtained. Can do.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of the present invention.
FIG. 2 is a plan view showing an embodiment of the present invention.
FIG. 3 is a conceptual diagram comparing an angle type solenoid valve and a straight type solenoid valve.
FIG. 4 is a perspective view showing a conventional batch backwash system.
FIG. 5 is a cross-sectional view showing a preceding pulse backwashing system.
[Explanation of symbols]
1 container, 2 support plate, 3 exhaust gas inflow chamber, 4 clean room, 5 exhaust gas inlet, 6 clean gas outlet, 7 backwash pipe, 8 backwash nozzle, 9 straight solenoid valve, 10 pipe, 11 container ceiling Surface, 12 Vertical pipe, 13 Angle type solenoid valve, 14 Solenoid, 15 Disc, 16 Valve seat, 17 Inlet flow path, 18 Outlet flow path, 19 Header pipe, C Ceramic filter

Claims (1)

A pulse backwashing device for a plurality of ceramic filters whose necks are supported by a support plate in a container, wherein a backwashing nozzle having a tip opposed to one or several ceramic filters is connected to the tip and the ceramic filter. A large number of pipes connected to the base of each backwash nozzle are pulled out to the outer circumference of the container horizontally through the top of the support plate with a distance of 20 to 40 mm from the upper end, and the flow rate of the valve is counted. A pulse backwashing device for a ceramic filter, which is connected to a header on the outer periphery of a container through an angle type solenoid valve having a Cv value of 80 or more .

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