JPS6038183B2 - Air filter intermittent external charging method and device - Google Patents

Description

[Detailed Description of the Invention] This invention uses a dielectric as a furnace material to increase the winding efficiency of an air filter, which has a low pressure loss, a large dust holding capacity, a small increase in pressure drop, and a relatively low collection efficiency, to a set range. The present invention also relates to a method for maintaining the collection efficiency of an air filter within a set range over a long period of time, and an intermittent external charging device for carrying out the method.

Air filters whose furnace materials are made of synthetic fibers such as polypropylene and polyester, which easily generate static electricity, and inorganic fibers such as glass fibers, have low pressure loss (pressure loss) and large dust retention capacity. However, the bottle collection efficiency is relatively low.

In addition, the filter's lifespan is shortened because the collection efficiency gradually decreases due to the adhesion of dust, especially cigarette smoke, floating in the air during use. However, the average colorimetric efficiency of the neutral bear filter needs to be about 80% or more. To this end, conventionally, as shown in Fig. 1, a particle charging device 3 is installed in front of an air filter 2 with a dielectric material as a furnace 1, and by strongly charging floating dust in the air, the air filter 1 collects air filter particles. It was increasing efficiency.

(This is called a particle charge filter.) Also, as shown in FIG. 2, the dielectric furnace material 1 is sandwiched between two electrodes and a high voltage is applied to polarize and charge the dielectric furnace material 1. The electrostatic force strongly attracts floating dust in the air and collects it in a bottle, increasing the efficiency of the filter. (This is called an electrostatic dielectric filter.) However, in these ordinary particle-charged filters and electrostatic dielectric filters, that is, externally charged filters, high voltage is constantly applied, so the efficiency of the filter is reduced. is much higher than the required standard value, and is wasting power and energy.

Therefore, an object of the present invention is to solve the problems of the conventional examples, and to provide an externally charged air filter such as the above-mentioned particle charged filter and electrostatic dielectric filter, in which the external charge is intermittently applied. applying the air filter to increase the collection efficiency of the air filter to the set range, and maintain the bottle collection efficiency of the air filter within the set range for a long period of time,
Furthermore, it is an object of the present invention to automatically control intermittently applied external charging by an intermittent external charging device, thereby extending the life of the air filter, and saving power and energy.

The method and charging device of the present invention will be described in detail below.

The upstream side of a particle charging filter in which a particle charging device 3 is provided in front of an air filter 2 with a dielectric layer 1, or an electrostatic dielectric filter in which a transfer material 1 is placed between two electrodes. And on the downstream side, a number of particles in the air are attached to the Aikomimine army Mominmi dance.

The air filter 2 has a low pressure loss and pressure drop increase rate, and has a large dust holding capacity.The furnace material 1 is made of synthetic fibers such as polypropylene and polyester, and inorganic fibers such as glass fibers.

The shape of the filter may be any one commonly available on the market, such as a box type filter made of corrugated furnace material with appropriate spacing plates sandwiched therein, a bag filter, a pocket type filter, etc., but is not particularly limited. In the case of a particle-charged filter, a wedge-shaped bag filter with low air resistance is preferred because it is easy to replace the furnace. or,
In the case of an electrostatic dielectric filter, the electrode 4 is made of wire gauze, mesh, or a breathable material whose fiber surface is made electrically conductive by plating or metal vapor deposition. It is preferable in terms of dust retention capacity, filter fabrication, etc. The particle charging device 3 applies a DC high voltage to charge floating dust particles in the air, and the applied current voltage is 3 to 1 V, but in this example, it is 5 to 1 V.
However, the applied voltage of Z was preferable. Also, to prevent the generation of harmful ozone, a high positive voltage is usually applied. Then, the suspended particles in the airflow that entered the high electric field of the particle charging device 3 are strongly positively charged, and this exerts an image effect on the fiber material constituting the fibrous furnace material 1 on the downstream side, causing the surface of the fiber material to become The charged particles are strongly polarized and charged (the part close to the charged particles is negatively charged, and the part far away is positively charged), and the charged particles are strongly attracted to the fiber material constituting the downstream dielectric furnace material 1 due to the image force.

That is, as shown in FIG. 3, the bottle collection efficiency of the air filter increases significantly from the initial collection efficiency of the air filter. Therefore, in this invention, the upper and lower limits of the required vertical collection efficiency are set according to the use of the air filter.
Intermittent external charging is performed in which external charging is stopped when the bottle collection efficiency reaches the upper limit efficiency, and external charging is restarted when the bottle collection efficiency decreases to the lower limit efficiency.

The graph of FIG. 3 shows an example of a medium-performance square filter, in which the upper limit of the collection efficiency is set to 90% and the lower limit of the collection efficiency is set to 80%.

In other words, when there is no external charging, the bottle collection efficiency of the air filter gradually decreases as the air filter is used, but when external charging is used in conjunction with intermittent external charging as described above, the bottle collection efficiency decreases. Efficiency remains within its set range over time. In order to measure the collection efficiency of this air filter, it is necessary to simultaneously measure the suspended dust concentration on the upstream and downstream sides of the air filter using the sensor 5.

Such sensors include, for example, laser scattering sensors (measures particle number concentration), piezo-balanced sensors (
There are various types of sensors, including a sensor that measures particle weight (measures particle weight concentration) and a condensation nucleus measurement type sensor (measures the degree of particle stimulation), and any of them can be used. The electrical signals output from these sensors 5 are transmitted to an intermittent external charging device having a system as shown in FIG. 5, according to the signal diagram shown in FIG. The electrical signal is converted into a numerical signal by a pulse height analyzer 6, giving a reading value on the upstream side and a cutoff value leg on the downstream side.

This read value (B) is processed in the microcomputer 7, and the external charging of the intermittent external charging device is determined by the upper limit efficiency (H) and lower limit efficiency (L) of the collection efficiency set above. It is turned OFF within the range, and turned ON when the efficiency falls below the lower limit efficiency (L). That is, the filter efficiency {EIGma(1-B/A)xlo
If the collection efficiency (E) is larger than the upper limit efficiency (H) (YES), external charging is stopped, and conversely, if the collection efficiency 'E) is smaller than the upper limit efficiency (H) (NO), And if this Urasumi efficiency [E} is larger than the lower limit efficiency (L), then (Y
ES) External charging is stopped, and if the collection efficiency {E} is even smaller than the lower limit efficiency (L) (NO) external charging is started. This external charging is continued until the Ura collection efficiency [E] reaches the upper limit efficiency (H). With such a control system, the external charge is applied intermittently and the air filter maintains the collection efficiency within a set range.

Note that the application of the external voltage can be carried out using a normal continuous voltage, and the following method may also be considered.

For example, pulses ON, O as shown in A, C, and C in Figure 6
The chopper voltages with different FF time ratios are adjusted as appropriate by a microcomputer depending on the collection efficiency of the filter.
Instruct appropriate external charging.

In other words, when the filter efficiency is relatively high, the pulse duration is shortened and the chopper voltage is set; when the filter efficiency is low, the chopper voltage is set to a long pulse duration, and when the filter efficiency is slightly low, the chopper voltage is set to By applying a chopper voltage with a pulse duration in between, the efficiency of the air filter can be maintained within a set range. As described above, the present invention performs intermittent external charging to increase the collection efficiency of the air filter to a set range, maintain the collection efficiency of the air filter within the set range over a long period of time, and By automatically controlling the external charge that is applied to the air filter using an intermittent external charging device, the air filter is designed to extend its life, save power, and save energy. Brief explanation of the drawings Figure 1 is an explanatory diagram showing the method of applying external charges in a particle charge filter, Figure 2 is an explanatory diagram showing the method of applying external charges in an electrostatic dielectric filter, and Figure 3 is an explanatory diagram showing the method of applying external charges in a particle charge filter. An explanatory diagram showing the collection efficiency of the air filter when the method of the invention is implemented, FIG. 4 is a signal system diagram of a device that implements the method of the invention, and FIG. Figure 6 A, C and C are explanatory diagrams showing the chopper voltage.

1...Dielectric furnace village, 2...Air filter, 3...,. ．． Particle charging device, 5...sensor. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. An air filter that uses a dielectric material as a filter material, has low pressure loss, large dust holding capacity, low pressure drop increase, and relatively low collection efficiency, is subjected to an intermittent external charge to adjust the collection efficiency as appropriate. A method for intermittent external charging of an air filter, characterized in that the air filter is raised to a set range and maintained within the set range. 2. The intermittent external charging method for an air filter according to claim 1, wherein the external charging is by a sustained voltage. 3. The intermittent external charging method for an air filter according to claim 1, wherein the external charging is by a chopper voltage. 4. Sensors for detecting dust are installed on the upstream and downstream sides of an air filter that uses a dielectric material as a filter material, has low pressure loss, large dust holding capacity, low pressure drop increase, and relatively low collection efficiency, and externally charges the air filter. A device for applying the voltage is provided, and the output signals from both of the sensors are input to a microcomputer, and the collection efficiency obtained from both output signals is compared with the lower limit efficiency of the collection efficiency range inputted in advance.
If the collection efficiency is greater than the lower limit efficiency, external charging is stopped, while if it is less than the lower limit efficiency, external charging is started and the collection efficiency is further compared with the upper limit efficiency. A method for intermittent external charging of an air filter, characterized by comprising a control system that continues external charging if the efficiency exceeds an upper limit, and stops the external charging if the efficiency exceeds an upper limit. 5. The air filter intermittent external charging device according to claim 4, wherein the external charging is by a sustained voltage. 6. The air filter intermittent external charging device according to claim 4, wherein the external charging is based on a chopper voltage.