JPH0459939B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic precipitator, and particularly to an electrostatic precipitator suitable for installation in a road tunnel.

[Prior Art] For example, the air inside a car tunnel contains many submicron-sized suspended particles such as soot emitted from cars, tires generated by driving cars, and dust generated by abrasion of asphalt on roads. It's contaminated. As a method of cleaning and ventilating the contaminated air inside the tunnel, ventilation equipment using an electrostatic precipitator is installed in the detour tunnel in the tunnel leading to the roadway, and the contaminated air exhausted from the roadway is passed through the electrostatic precipitator. A system has been developed that cleans the air and re-injects it into the roadway.

Next, an outline of such an electrostatic precipitator is shown in FIG. 2. In the figure, 1 is a detour tunnel that leads to the roadway inside the tunnel described above, and within this tunnel 1, an electrostatic precipitator main body 2 and a blower 3 are installed on the downstream side thereof.

The electrostatic precipitator main body 2 is equipped with opening/closing dampers 5 and 6 on the inlet and outlet sides of the casing 4, and a high voltage power supply 7 inside the casing 4.
A dust collecting unit is provided which includes a charging electrode unit 8 and a dust collecting electrode unit 9 which receive power from the charging electrode unit 8 and the dust collecting electrode unit 9, respectively.

During operation, contaminated air A is drawn into the electrostatic precipitator body 2 from the upstream side by the blower 3.
As is well known, during the process of passing through the dust collection unit, suspended particulates contained in the contaminated air A are collected as dust on the dust collection electrode of the dust collection electrode unit 9, and the purified air A' is sent to the blower 3. is sent downstream through the

Here, in order to separate and recover the dust collected on the dust collection electrode, on the one hand, the dust collection electrode unit 9 is
A plurality of air blow nozzles 10 for dust removal are arranged downstream of the unit 9 in the vicinity of the same unit 9, and a compressor 11 is connected to the air blow nozzles 10 via an air blow line 12, so that the jet from the air blow nozzles 10 is Spray toward the interlayer gap of the dust collection electrode unit.

On the other hand, a dust discharge plenum 13 is formed at the bottom of the casing of the dust collector body, and a dust separation and recovery device 14 such as a bag filter or a cyclone and a suction fan 15 are connected to this plenum 13 via a dust recovery line 16. In addition,
17 is an opening/closing drive unit for the dampers 5 and 6; 18 is a main valve of the air blow line 12; and 19 is an opening/closing damper provided on the outlet side of the dust discharge plenum 13.

Next, the dust removal and dust collection operations with the above configuration will be explained with reference to FIGS. 3 and 4.

First, during dust collection operation, as shown in Fig. 3, the compressor 11 is connected to the air blow line 12 and the suction fan 1 is connected to the dust recovery line 16.
5 are stopped, and in this state, the electrostatic precipitator opens dampers 5 and 6 and receives power from the power supply device 7 to collect contaminated air.

When this dust collection operation continues for a certain period and dust is collected and deposited on the dust collection electrode, the dust attached to the dust collection electrode is then brushed off and collected by a dust cleaning command. . In this case, first stop the power supply to the blower 3 and high voltage power supply 7, then start the compressor 11 and suction fan 15 as shown in FIG. 5 and 6 are closed, and the main valve 18 of the air blow line and the opening/closing damper 19 of the dust discharge plenum are opened to start the dust dust removal and collection operation. That is, from the air blow nozzle 10, gas is supplied under pressure through the air blow line 12, and is ejected at a wind speed close to the speed of sound toward the interlayer gap of the dust collection electrodes constituting the dust collection electrode unit 9, and is deposited on the electrodes. Brush off any dust that may be present. Here, the dust collected on the dust collection electrode is aggregated and coarsened, and the coarse particle dust brushed off from the electrode is ejected into the casing from the air blow nozzle 10 and passed toward the dust collection line 16. It is dispersed in the flowing carrier air stream B, and is sucked and carried out to the dust collection line 16 outside the machine through the dust discharge plenum 13. Furthermore, the dust riding on the carrier airflow enters the dust separation and recovery device 14 where it is separated from the carrier airflow, and only the airflow is discharged through the suction fan 15 to the upstream side of the electrostatic precipitator 2, for example. On the other hand, in the separation and recovery device 14, the dust separated and recovered from the conveying airflow is appropriately repacked into a bag or the like and then transported to a processing plant where it is disposed of. By the above-described solid dust removal and collection method, the dust collected in the dust collector can be smoothly discharged and separated and collected without being scattered again.

On the other hand, the electrostatic precipitator described above is required to have a high processing air velocity and a high dust collection rate.

For example, one with a processing wind speed of 7 m/s and a dust collection rate of 80% is in practical use.

On the other hand, since excavating detour tunnels costs a huge amount of money, recently it has been considered to install electrostatic precipitators in roadway tunnels instead of in such detour tunnels.

[Problems to be Solved by the Invention] However, the conventional electrostatic precipitator as described above does not provide satisfactory performance as equipment installed in a roadway tunnel. In other words, installation space, especially the wind intake cross-sectional area, is limited inside a roadway tunnel, and this is a factor that makes it difficult to install a conventional electrostatic precipitator with the above-mentioned performance inside a roadway tunnel. I was getting used to it.

Therefore, the purpose of the present invention is to solve the above-mentioned problems, and to provide a high-performance, compact and lightweight electrostatic precipitator with improved performance per unit of air intake cross-sectional area, making it suitable for installation in roadway tunnels, for example. The goal is to provide equipment.

[Means for Solving the Problems] To this end, the present invention arranges in series at least two dust collecting units each consisting of a charging electrode unit and a dust collecting electrode unit in a casing, The dust collection electrode unit in the downstream unit is characterized in that it has a shorter depth dimension than the dust collection electrode unit in the upstream unit.

[Example] FIG. 1 shows an example of the present invention. In FIG. 1, the same parts as in FIG. 2 are denoted by the same reference numerals, and detailed explanation will be omitted.

In Fig. 1, 1' is the upper space of the roadway tunnel (underneath this upper space, a lower space is formed via a suitable floor member, and this lower space is a normal roadway), and 2 is the upper space of the road tunnel. The main body of the electrostatic precipitator provided in the space 1', 3 is also a blower.

The electrostatic precipitator main body 2 is equipped with opening/closing dampers 5 and 6 on the inlet and outlet sides of the casing 4, and inside the casing 4 are two sets of dust collectors each supplied with power from high-voltage power supplies 7 and 7'. The units are arranged in series and close to each other in the flow direction of the gas to be treated. The dust collecting unit consists of charging electrode units 8, 8' and dust collecting electrode units 9, 9'.

During operation, contaminated air A is introduced into the upper space 1' from the lower space of the roadway tunnel through the ventilation holes formed in the ceiling (floor of the upper space 1').
is sucked into the electrostatic precipitator main body 2 from the upstream side by the blower 3, is removed as it passes through the main body 2, and is sent downstream through the blower 3 as clean air A' to fill the upper space. 1' into the lower space.

Multiple stages of air blow nozzles 10 (in the vertical direction)
is located close behind the downstream dust collection unit.

Reference numeral 11 denotes a compressor, which supplies compressed air to the air blow nozzle 10 via an air blow line 12.
supply to. 13 is a dust discharge plenum formed in the lower part of the casing 4, and 14 is a dust separation and recovery device, which is connected to the dust discharge plenum 13 via a dust recovery line 16 and an opening/closing damper 19. 18 is a main valve of the air blow line 12.

Of the two sets of dust collection units, the depth dimension of the dust collection electrode unit 9' of the downstream unit is shorter than the depth dimension of the dust collection electrode unit 9 of the upstream side. Even though the depth dimension is short, the dust collection rate of the downstream dust collection unit is almost the same as that of the upstream dust collection unit. This is considered to be due to the following reasons. For example, as shown in FIG. 6, which shows the particle size distribution of the test dust-containing air before and after dust collection, the suspended particles in the test air coagulate and become enlarged by being charged by the charging electrode unit.

Therefore, suspended particulates in the contaminated air are agglomerated and enlarged by the charging action of the charged electrode of the upstream dust collection unit, and are collected by the dust collection electrode of the same unit, leaving behind (uncollected) particles. The fine particles reach the downstream dust collection unit in a coagulated and enlarged state. Therefore, the amount of charge of suspended particles on the charging electrode of the downstream dust collection unit becomes larger than that on the upstream dust collection unit (this tendency becomes more pronounced as the two sets of dust collection units are closer together). The charged fine particles that have passed through the dust collection unit are collected by the dust collection electrode in the downstream dust collection unit over a short traveling distance (compared to the upstream dust collection unit). As a result, even if the depth dimension of the dust collection electrode of the downstream dust collection unit is shortened, the dust collection rate does not decrease. Even if electrostatic precipitators each having only one dust collection unit of the same size are simply arranged in series, the upstream device cannot expect much of the effect of electrostatic aggregation and enlargement of suspended particles in the downstream device. In this way, according to the present invention, only one casing is required, and there is no need to increase the casing size that much, and additional equipment such as air blow nozzles can be shared, so a device with high dust collection efficiency can be made extremely compact and lightweight. It can be obtained at a low price.

Incidentally, the effect of improving the dust collection rate by the electrostatic precipitator of the present invention having the configuration shown in FIG. 1 is as follows. In other words, the depth of the casing is increased, and the downstream dust collection unit is placed close to the upstream dust collection unit (however, the depth of the dust collection electrode unit 9' in the downstream dust collection unit is the same as that of the upstream dust collection electrode unit 9). The dust collecting apparatus of the present invention shown in FIG. 1 was created to have substantially the same structure as the conventional dust collecting apparatus shown in FIG. 2 except for the arrangement of the dust collecting apparatus shown in FIG.

The conventional dust collector shown in Figure 2 has a wind speed of 7m/
While the dust collection rate of contaminated air in S was 80%, the dust collection device of the present invention shown in Fig. 1 had a wind speed of 7 m/min.
The dust collection rate of S contaminated air was 96%.

Considering this conceptually, the dust collection rate by the upstream dust collection unit is 80%, and the dust collection rate by the downstream dust collection unit is also 80% for the contaminated air (after passing through the upstream unit). % (i.e., overall 96% of the contaminated air before treatment)
This is thought to be due to the fact that the

FIG. 5 shows the configuration of another embodiment of the present invention. In this embodiment, an air blow nozzle 10 capable of spraying in the front and back direction is arranged between an upstream dust collection unit and a downstream dust collection unit that are arranged in series, and the air blow nozzle 10 that can spray air in the front and back direction is further installed at the bottom of the downstream side of the casing 4 to blow air into a dust discharge plenum 13. Dust discharge nozzle 20 with outlet facing
The other structure is almost the same as the structure shown in the first drawing. In addition, the discharge nozzle 20
, the air from the suction fan 15 is transferred to a damper 19'.
Supply via.

Even with such a configuration, contaminated air can be removed with extremely high efficiency, and
Since the air blow nozzle 10 is located between the upstream and downstream dust collection units, it is possible to more efficiently blow off the dust adhering to both dust collection units. Furthermore, the dust that has been blown off and accumulated at the bottom of the casing 4 is removed by the dust discharge nozzle 20.
This makes it possible to efficiently send the dust to the dust discharge plenum 13, thereby further increasing the dust discharge efficiency.

FIGS. 7 and 8 show a schematic arrangement of a dust collection unit and an air blow nozzle in still another embodiment of the present invention. In FIG. 7, an air blow nozzle 10' is arranged close to the charging electrode unit 8 from the upstream side, and the compressor 1
FIG. 8 shows an example in which compressed air from 1 is supplied through an air blow line 12, and FIG. 8 shows an example in which an air blow nozzle 10' is arranged above two current collecting units. It is clear that either structure can efficiently remove dust adhering to the dust collection unit, provide a high dust collection rate, and can be made smaller and lighter.

[Effects of the Invention] As explained above, according to the present invention, a compact and lightweight electrostatic precipitator which has an extremely high dust collection rate, requires only one casing, and can be miniaturized. Obtainable.
As a result, it is possible to install an electrostatic precipitator in a roadway tunnel and clean the inside of the roadway tunnel, without using the detour tunnel method, which costs a huge amount of money, for example.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view of a conventional electrostatic precipitator, FIGS. 3 and 4 are sectional views of essential parts of the conventional electrostatic precipitator, and FIG.
7 and 8 are cross-sectional views of other embodiments of the present invention, and FIG. 6 is a diagram showing the particle size distribution before and after dust collection. 8, 8'... Charging electrode unit, 9, 9'... Dust collecting electrode unit.

Claims (1)

[Claims] 1 At least two dust collection units consisting of a charging electrode unit and a dust collection electrode unit are arranged in series in the casing, and the dust collection electrode unit in the downstream unit of the at least two dust collection units is connected to the dust collection unit in the upstream unit. An electrostatic precipitator characterized by having a depth dimension shorter than that of a dust electrode unit.