JP2009039639A - Electric dust collection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric dust collection system which enables the removal of harmful nitrogen dioxide in an amount corresponding to an increase by an electric duct collector and whose construction cost and electric consumption cost can be suppressed to the minimum by advantageously utilizing narrow spaces of tunnel ventilation places existing many in a large city. <P>SOLUTION: An electric dust collector with high treatment air blow velocity and an electric dust collector with slow treatment air blow velocity are arranged in parallel and a NO<SB>2</SB>reduction catalyst or a NO<SB>2</SB>adsorbent or a NO<SB>2</SB>absorbent (which increases pressure loss) is installed downstream of the electric dust collector with slow treatment air blow velocity (that is, pressure loss is low) to give an electric dust collection system capable of removing SPM and simultaneously suppressing NO<SB>2</SB>increase. Further, since the electric dust collector with slow treatment air blow velocity is employed, the installation space can be relatively narrow. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric dust collection system for removing suspended particulate matter (SPM) in exhaust gas from a motorway tunnel.

  In recent years, the need to remove SPM (suspended particulate matter) in tunnel exhaust gas discharged from a ventilator of an automobile road tunnel has been increasing due to the heightened environmental awareness. As this measure, it is conceivable to install an electrostatic precipitator for environmental measures in the exhaust ventilation path of the tunnel ventilation station, and the number of installations tends to increase. A typical example of the exhaust gas properties of road tunnels in urban areas in Japan is data (components of exhaust gas to be processed) in the Tokyo Metropolitan Expressway Central Loop Shinjuku Line shown in Table 1 below.

  Further, in the second term of the technical book “National Technical Report June 1995” (Non-Patent Document 1) of Matsushita Electric Industrial Co., Ltd., there is the following description of NOx (nitrogen oxide). “……… NO accounts for about 90% of the NOx in the tunnel exhaust gas ………”. This description is generally recognized and shared by the general public. To describe it in more detail, it is said that "about 90% of NOx in tunnel exhaust gas is NO and the remaining about 10% is NO2." You can express it. Therefore, it can be seen from Table 1 that the average value of the nitric oxide concentration in the tunnel is 0.9 ppm.

  The structure of the electrostatic precipitator for the tunnel is generally shown in FIG. 3 of Japanese Patent No. 3150431 (Patent Document 1). A charging unit that generates corona discharge and charges the dust, and a parallel plate In this configuration, a high voltage is applied, a strong electric field space is formed, and a dust collecting portion that collects charged dust particles is collected. A system that generates a corona discharge by applying a positive high voltage is called a positive discharge system, and a system that generates a corona discharge by applying a negative high voltage is called a negative discharge system.

  The theoretical formula of dust collection by electrostatic precipitators has been known for a long time as “Deutsch's formula”. “Static Handbook” (Non-patent Document 2) of the Institute of Electrostatics and “Electrical Engineering Handbook” (Non-patented) Document 3) shows the following.

η = 1−exp (−K1 · E · S / Q) ...... Deutsch's formula (1)
Here, η is the dust collection efficiency, E is the electric field strength of the dust collection electrode plate, S is the total area of the dust collection electrode plate, Q is the air volume, and K1 is a value related to the charging ability of the charging unit.

  The Deutsche equation (1) can also be expressed as follows, and its essential meaning remains unchanged.

η = 1−exp {−K ₂ · E · L / (v · d)} ...... Deutsch equation (2)
Here, η is the dust collection efficiency, L is the length of the dust collecting electrode plate in the flow direction, v is the processing wind speed, d is the distance between the dust collecting electrode plates, and K ₂ is a value related to the charging ability of the charging unit. .

  The electric dust collector for tunnels was first specified in the world as an official document in the 1987 edition of the Japan Highway Public Corporation (now Nippon Expressway Co., Ltd.) “Mechanical Telecommunications Equipment Specification” (Non-Patent Document 4). It was “Standard Specification for Electric Dust Collector Equipment for Tunnels”. Later, the specifications were revised, and Table 2 below. I traced the transition.

  * 1: “Unit” refers to the minimum component of electrostatic dust collection consisting of one charging unit and one dust collection unit.

  * 2: Power consumption was not stipulated in the 1987 edition, but at that time, electric dust collectors were manufactured with figures in parentheses.

The 1996 specification in Table 2 is described below in comparison with the 1987 specification, with reference to the Deutsch equation.
1) The processing wind speed is about 1.3 times larger. Naturally, the “process air volume / unit” has also increased by about 1.3 times.
2) As the wind speed increases, the pressure loss naturally increases. The pressure loss increases at about the square of 1.3 times the wind speed increase rate.
3) According to the Deutsche equation (2), if the wind speed increase rate (value related to v) and the dust collection plate length increase rate (value related to L) are not equal, the same dust collection as the 1987 specification Efficiency (η) cannot be obtained. Only by making the length of the dust collecting electrode plate sufficiently long, the cost and pressure loss of the dust collecting part will rise too much and become uneconomical, so the increase in the length of the dust collecting electrode plate was suppressed to some extent. .
4) Therefore, in order to compensate for the decrease in the dust collection capacity of the dust collection section, a method for obtaining the same dust collection efficiency as in the 1987 specification was selected by increasing the charging section charging capacity (K2) itself. In other words, the corona discharge capability of the charging part has been enhanced.
5) Accordingly, the power consumption [W / (m ³ / s)] is increased by about 1.5 times. Naturally, the cost of the charging part increased.
6) In addition, the cost of the dust collector has increased, so the overall cost of the electric dust collector has increased by increasing the wind speed.
7) Increasing the wind speed increased the cost of the electrostatic precipitator, but the number of electrostatic precipitators was reduced and the entire facility was miniaturized, making it possible to save civil engineering construction costs for the ventilation station. In other words, we succeeded in reducing the total cost including equipment costs, civil engineering costs and construction costs.

Furthermore, the 2006 specifications in Table 2 are described below in comparison with the 1996 specifications.
1) There is no change in processing air speed and “processing air volume / unit”.
2) The dust collection efficiency is increased to 90%. According to the Deutsche equation (2), the charging capacity (K ₂ ) is further doubled to achieve the dust collection efficiency.
3) The cost of the charging part naturally increased.
4) We succeeded in reducing the total cost including equipment costs, civil engineering costs and construction costs.

  Although the explanation in Table 2 has been described above, as a recent trend, an electrostatic precipitator specification in which the processing wind speed is increased to 13 m / s has appeared. In this case, the pressure loss is about 350 Pa, which is a larger value than the 2006 specification.

  In addition to the original function of removing SPM, the electrostatic precipitator actually has a negative function. There is the following description in the published patent “International Publication Number WO2006 / 009187” (Patent Document 2). “Because the electrostatic precipitator uses corona discharge in the charging section, harmful ozone is generated as a by-product. Especially in the tunnel, there is a lot of nitric oxide, so the nitric oxide is oxidized by ozone. There is also the problem of increasing harmful nitrogen dioxide. "

  Three types of gas components appear in the wording. Table 3 is obtained by summarizing the regulation values of each gas component.

  * 1: American Conference of Government Industrial Hygienist; American Occupational Health Supervisory Council.

The points to be noted in Table 3 are as follows.
1) The allowable concentration of nitric oxide is “25 ppm or less” according to US standards.
2) The allowable concentration of nitrogen dioxide is “0.04 to 0.06 ppm or less” according to Japanese environmental standards.
3) Therefore, compared with the permissible concentration, nitrogen dioxide is harmful to the human body several hundred times more than nitric oxide.
4) Therefore, it is obvious that it is not preferable that the concentration of nitrogen monoxide is increased to nitrogen dioxide due to ozone generated from the environmental dust collector.

  Similarly, the international publication number WO2006 / 009187A1 (patent document 2) describes the ozone concentration level generated by the electrostatic precipitator. Table 4 is obtained by extracting and summarizing a part. As follows.

  * 1 and * 2: All data are values when a discharge wire is used as the discharge electrode.

The ozone concentration generated from the 1996 electrical dust collector and the 2006 electrical dust collector in Table 2 is calculated by converting the value in Table 4 when the applied voltage of the charging unit is 11 kV.
1) Since the processing wind speed of the unit of 5 m ³ / s is 9 m / s, a cross-sectional area of the ventilation portion of 0.56 m ² is obtained.
2) In the case of positive discharge, the ozone concentration is 0.006 ppm when a wind of 1 m / s is passed through a cross-sectional area of 1 m ² and power consumption of 1 W is applied.
In 3), according to the 1987 specification, the ozone concentration is 0.0162 ppm when a wind of 7 m / s is passed through a cross-sectional area of 0.54 m ² and a power consumption of 35 W is given. Similarly, it becomes 0.0999 ppm in minus discharge.
4) Further, in the case of positive discharge in the 1996 specification, the ozone concentration is 0.0205 ppm when a wind of 9 m / s is passed through a cross-sectional area of 0.56 m ² and power consumption of 55 W is given. Similarly, in the negative discharge, it becomes 0.1264 ppm.
5) Also, in the 2006 specification, the ozone concentration is 0.0410 ppm when a wind of 9 m / s is passed through a cross-sectional area of 0.56 m ² and a power consumption of 110 W is applied. Similarly, in the negative discharge, it becomes 0.2528 ppm.
The reaction formula in which nitric oxide is oxidized to nitrogen dioxide by ozone is as follows.

NO + O ₃ → NO ₂
From Table 1, the average value of the nitrogen monoxide concentration in the tunnel is 0.9 ppm, which is higher than the ozone concentration generated by the electrostatic precipitator. That is, ozone generated in the electrostatic precipitator is all consumed in the oxidation reaction from nitric oxide to nitrogen dioxide. That is, it can be considered that the ozone concentration generated in the electrostatic precipitator is directly increased by the nitrogen dioxide concentration.

  To conclude the above, for example, when an electric dust collector of 2006 specification is used, the increase in nitrogen dioxide when using a positive discharge type electric dust collector is 0.041 ppm, and in the negative discharge type, 0.253 ppm. Will be. It can be said that the electrostatic precipitator increases more or less harmful nitrogen dioxide.

When the average concentration of nitrogen monoxide NO in the exhaust gas is 0.9 ppm and the average concentration of nitrogen dioxide NO _{2 in} the exhaust gas is 0.1 ppm, the increase in nitrogen dioxide due to ozone when using the above electric dust collector In summary, Table 5 is obtained.

As a method of removing nitrogen dioxide in exhaust gas,
1) Many methods using an adsorbent have been reported in JP-A-11-57399 (Patent Document 3) and the like.
2) Moreover, the method using the absorber shown by patent 2690257 (patent document 4) is also reported.
3) Further, in JP 2000-325755 (Patent Document 5) has described that "it is preferable to use those having a reducing action of the NO ₂ → NO as porous carbon material or the like", NO ₂ A method using a reducing agent from NO to NO has also been reported.

Since activated carbon is also included in the porous carbon material in 3), it is obvious that the absorbent and adsorbent using activated carbon also have a certain amount of NO ₂ to NO reducing action.

Further, it is obvious that an increase in pressure loss is accompanied by arranging these adsorbent, absorbent, and reducing agent in the ventilation path in order to remove nitrogen dioxide in the exhaust gas.
National Technical Report June 1995 "Static Handbook" of the Electrostatic Society "Electrical Engineering Handbook" by the Institute of Electrical Engineers of Japan Japan Highway Public Corporation “Mechanical and Telecommunications Equipment Specifications” Japanese Patent No. 3150431 International Publication No. 2006/009187 Pamphlet Japanese Patent Laid-Open No. 11-57399 Japanese Patent No. 2690257 JP 2000-325755 A

  FIG. 9 is a plan view showing a conventional arrangement of an electric dust collection system in a tunnel ventilation station. An electrostatic precipitator 101 is arranged in parallel in the air passage. (In this figure, six units are arranged as an example.) Dust-containing air containing SPM flows into the electrostatic precipitator 101 from the inflow side, and SPM is removed from the outflow side of the electrostatic precipitator 101. Dust removal air is flowing out. Note that a ventilation fan (not shown) for ventilating the electric dust collection system is provided in the ventilation station. (Ventilation fans are also called ventilation fans, exhaust fans, etc.) Ventilation fans are usually of variable air volume.

Since the electrostatic precipitator has the disadvantage of increasing the nitrogen dioxide, which is a harmful substance, more or less, it is conceivable to remove the portion of the nitrogen dioxide increased by the electrostatic precipitator system. FIG. 10 shows an electrostatic precipitator 101 arranged in parallel with the air passage in the tunnel ventilation station, and a NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent 102 also arranged in parallel on the outflow side. It is a plane layout view of the arranged electric dust collection system, so far can be easily thought.

However, the above configuration has the following problems.
1) the entire cross-section of the downstream side of the electrostatic precipitator 101, placing the absorbent 102 in the adsorbent or NO ₂ of the reduction catalyst or NO ₂ of NO ₂ is required massive installation work, construction costs ( Initial cost).
2) In addition to the pressure loss of the electrostatic precipitator 101, the pressure loss of the NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent 102 is added, so that the ventilation power (ventilation power) of the ventilation fan is increased, This increases the electricity cost (running cost) for driving.

  Electricity that can effectively use the narrow space of tunnel ventilation stations that exist in large cities, and can eliminate the proportion of harmful nitrogen dioxide that has been increased by electrostatic precipitators, while minimizing construction costs and electricity costs. A dust collection system has been required.

In the electrostatic precipitator system according to the first aspect of the present invention, an electrostatic precipitator with a high processing wind speed and an electrostatic precipitator with a low processing wind speed are arranged in parallel, and NO ₂ is reduced on the downstream side of the electrostatic precipitator with a low processing wind speed. A catalyst, an NO ₂ adsorbent, or an NO ₂ absorbent is arranged.

In the electric dust collection system of the present invention, the pressure loss of the NO ₂ reduction catalyst, the NO ₂ adsorbent or the NO ₂ absorbent is such that the pressure loss of the electrostatic precipitator with the high processing wind speed and the processing wind speed are It is characterized by being equal to the difference with the pressure loss of a slow electrostatic precipitator.

  In the electric dust collection system according to the third aspect of the present invention, each electric dust collector is provided with an open / close damper that opens and closes the airflow that flows through the electric dust collector, and the open / close dampers have a structure that can be partially opened and closed independently. Features.

  In the electrostatic precipitator system according to the fourth aspect of the present invention, the high-voltage power supply for each electrostatic precipitator is constituted by a plurality of blocks, and these high-voltage power supplies can partially apply a high voltage to each electrostatic precipitator. It is characterized by being.

  According to a fifth aspect of the present invention, there is provided an electrostatic precipitating system according to the present invention, which is equipped with a control means capable of increasing / decreasing the corona discharge power of each electrostatic precipitator with a high voltage power source.

  The electric dust collector system of the present invention according to claim 6 divides an electric dust collector having a high processing wind speed and an electric dust collector having a low processing wind speed by a partition, and the air volume variable type ventilation for adjusting the processing air speed of the electric dust collector in each system. It is characterized by arranging a fan.

In the electric dust collection system of the present invention according to claim 7, a plurality of electric dust collectors are arranged in parallel, and a NO ₂ reduction catalyst or NO _{2 is provided} downstream of some of the plurality of electric dust collectors. of placing the absorbent adsorbent or NO2, upstream of electrostatic precipitator disposed to the downstream side of the absorbent adsorbent or NO ₂ of the reduction catalyst or NO ₂ of NO _2, arranged a guide vane, this By arranging the guide vanes, the processing wind speeds of all the electrostatic precipitators can be made equal.

In the electric dust collection system of the present invention according to claim 8, a plurality of electrostatic dust collectors are arranged in parallel, and a NO ₂ reduction catalyst or NO _{2 is provided} downstream of some of the plurality of electrostatic dust collectors. of the absorbent adsorbent or NO ₂ is arranged, on the downstream side of the rest of the electrostatic precipitator of the plurality of the electrostatic precipitator, the NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent equivalent A member having pressure loss is arranged.

The electrostatic precipitator system of the present invention according to claim 9 has a plurality of electrostatic precipitators arranged in parallel, and a NO ₂ reduction catalyst or NO _{2 is provided} downstream of some of the electrostatic precipitators. of the absorbent adsorbent or NO ₂ is arranged, on the downstream side, arranged and electrostatic precipitator placed an adsorbent or NO ₂ absorbent of the reduction catalyst or NO ₂ of NO _2, those on the downstream side The electric dust collector is separated from each other by partition walls, and a variable air volume ventilation fan for adjusting the processing air speed of the electric dust collector is arranged in each system.

According to a tenth aspect of the present invention, there is provided an electrostatic precipitator system in which a plurality of electrostatic precipitators are arranged in parallel, and a NO ₂ reduction catalyst or NO _{2 is provided} downstream of some of the plurality of electrostatic precipitators. The adsorbent or NO ₂ absorbent is arranged, and each electric dust collector is equipped with an open / close damper that opens and closes the airflow that is ventilated, and the open / close damper has a structure that can be partially opened and closed independently And

An electric dust collection system that can achieve both removal of SPM and suppression of NO ₂ increase can be constructed. In addition, it is possible to construct an electric dust collection system that can minimize the total amount (construction cost) of civil engineering and construction costs and equipment costs, and that can also minimize an increase in electricity bills.

The electrostatic precipitator system according to the first embodiment of the present invention includes an electrostatic precipitator having a high processing wind speed and an electrostatic precipitator having a low processing wind speed arranged in parallel, and the electrostatic precipitator of the electrostatic precipitator having a low processing wind speed (that is, low pressure loss). A NO ₂ reduction catalyst, an NO ₂ adsorbent, or an NO ₂ absorbent (which causes an increase in pressure loss) is disposed on the downstream side. Therefore, it is possible to obtain an electric dust collection system capable of suppressing NO ₂ increase simultaneously with SPM removal. With this arrangement, the sum of the pressure loss of the electrostatic precipitator with slow processing wind speed and the pressure loss of the NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent is Can approach the same level. Partially, an electrostatic precipitator with a slow processing wind speed is adopted, so the installation space is larger than that of an electrostatic precipitator system using only an electrostatic precipitator with a high processing wind speed, but only a slow electrostatic precipitator is used. The installation space can be reduced compared to the existing electric dust collection system. Since the NO ₂ reduction catalyst, the NO ₂ adsorbent or the NO ₂ absorbent is arranged in a part of the cross section of the air passage, the equipment for suppressing the NO ₂ increase can be minimized. Since the increase in facilities can be suppressed even at the expense of some space advantages, the overall construction cost advantage can be secured. Moreover, since an overall pressure loss similar to the pressure loss of an electric dust collection system using only an electric dust collector with a high processing wind speed can be realized, an increase in ventilation power (electricity cost) can be suppressed.

The electric dust collection system according to the second embodiment of the present invention includes a pressure loss of an NO ₂ reduction catalyst, an NO ₂ adsorbent, or an NO ₂ absorbent, a pressure loss of an electrostatic precipitator with a high processing wind speed, and a treatment. It is equal to the difference from the pressure loss of an electrostatic precipitator with slow wind speed. That is, the processing wind speed of the electrostatic precipitator with a high processing wind speed can be set to the rated processing wind speed, and the electrostatic precipitator with a low processing wind speed can also be set to the rated processing wind speed. Since the processing wind speed of each electrostatic precipitator can be set to the rated processing wind speed, it is possible to realize an operation that maximizes the SPM removal rate (dust collection efficiency), which is the original purpose of the electrostatic precipitator.

  In the electrostatic precipitator system according to the third embodiment of the present invention, each electrostatic precipitator is equipped with an open / close damper that opens and closes a flowing airflow, and these open / close dampers can be partially opened and closed independently. . Therefore, when the processing wind speed of the electrostatic precipitator with a high processing wind speed varies, and when the processing dust speed also varies with the electrostatic precipitator with a low processing wind speed, by partially opening and closing the damper, The processing wind speed can be finely adjusted to make it uniform. Operation that maximizes the SPM removal rate (dust collection efficiency), which is the original purpose of the electrostatic precipitator, can be realized.

In the electrostatic precipitator system according to the fourth embodiment of the present invention, the high-voltage power supply for each electrostatic precipitator is constituted by a plurality of blocks, and these high-voltage power supplies are partially applied with a high voltage to each electrostatic precipitator. It is possible. When the processing air volume of the entire electric dust collection system is operated at a value lower than the rated processing air volume, the increase in the concentration of NO ₂ generated from the electrostatic precipitator with a high processing air speed becomes too large, and the NO ₂ reduction catalyst or NO ₂ This may exceed the NO ₂ purification capacity of the adsorbent or the NO ₂ absorbent, and may increase NO ₂ in the entire electric dust collection system. In such a case, application of high voltage to the electrostatic precipitator with a high processing wind speed can be partially stopped to suppress an increase in NO ₂ in the entire electrostatic precipitator system.

The electric dust collection system according to the fifth embodiment of the present invention is equipped with a control means that can increase or decrease the corona discharge power of each electric dust collector with a high-voltage power supply. When the processing air volume of the entire electric dust collection system is operated at a value lower than the rated processing air volume, the increase in the concentration of NO ₂ generated from the electrostatic precipitator with a high processing air speed becomes too large, and the NO ₂ reduction catalyst or NO ₂ This may exceed the NO ₂ purification capacity of the adsorbent or the NO ₂ absorbent, and may increase NO ₂ in the entire electric dust collection system. In such a case, it is possible to finely adjust the corona discharge power of each electrostatic precipitator to reduce NO ₂ increase in the entire electrostatic precipitator system.

  The electrostatic precipitator system according to the sixth embodiment of the present invention partitions an electrostatic precipitator with a high processing wind speed and an electrostatic precipitator with a low processing wind speed by a partition, and the air volume is variable for adjusting the processing wind speed of the electrostatic precipitator in each system. A type ventilation fan is arranged. When the processing wind speed of an electrostatic precipitator with a high processing wind speed deviates from the rated wind speed and the electrostatic precipitator with a low processing air speed also deviates from the rated wind speed, the air volume of the variable air flow type ventilation fan of each system is finely adjusted. In addition, operation at the rated wind speed can be achieved. Operation that maximizes the SPM removal rate (dust collection efficiency), which is the original purpose of the electrostatic precipitator, can be realized.

The electrostatic precipitator system according to the seventh embodiment of the present invention includes a plurality of electrostatic precipitators arranged in parallel, and a NO ₂ reduction catalyst or a downstream side of the electrostatic precipitator of some of the plurality of electrostatic precipitators. An NO ₂ adsorbent or NO ₂ absorbent is arranged, and a guide vane is arranged upstream of the electrostatic precipitator in which the NO ₂ reduction catalyst, NO ₂ adsorbent or NO ₂ absorbent is arranged on the downstream side. And by arrange | positioning this guide vane, the process wind speed of all the electrostatic precipitators can be made substantially equivalent. According to this method, the rated processing wind speed of the electrostatic precipitator can be unified and manufactured. That is, the electrostatic precipitator can be manufactured at a low cost due to the mass production effect.

In the electric dust collector system according to the eighth embodiment of the present invention, a plurality of electrostatic dust collectors are arranged in parallel, and a NO ₂ reduction catalyst or a downstream side of some of the plurality of electrostatic dust collectors is disposed on the downstream side. the absorbent adsorbent or NO ₂ of NO ₂ is arranged, and a plurality of on the downstream side of the rest of the electrostatic precipitator of the electrostatic precipitator, NO ₂ of the reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent The members having the same pressure loss are arranged. By using a member having an equivalent pressure loss, the variation in the processing wind speed of the electrostatic precipitator can be made uniform, and the amount of expensive NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent used can be reduced. It can be minimized.

The electrostatic precipitator system according to the ninth embodiment of the present invention includes a plurality of electrostatic precipitators arranged in parallel, and a NO ₂ reduction catalyst or a downstream side of some of the electrostatic precipitators. An NO ₂ adsorbent or NO ₂ absorbent is disposed, and an NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent is disposed on the downstream side, and these are disposed on the downstream side. An electric dust collector that is not arranged is partitioned by a partition, and a variable air volume ventilation fan for adjusting the processing air speed of the electric dust collector is arranged in each system. By using a plurality of ventilation fans, it is possible to correct the imbalance between the processing wind speeds of the electrostatic precipitator in which the NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent is arranged on the downstream side and the non-arranged electric precipitator. it can. In other words, the uniform processing wind speed can realize an operation that maximizes the SPM removal rate (dust collection efficiency), which is the original purpose of the electrostatic precipitator.

The electrostatic precipitator system according to the tenth embodiment of the present invention includes a plurality of electrostatic precipitators arranged in parallel, and a NO ₂ reduction catalyst or a downstream side of a part of the electrostatic precipitators of the plurality of electrostatic precipitators. An NO ₂ adsorbent or an NO ₂ absorbent is disposed, and each electric dust collector is equipped with an open / close damper that opens and closes the airflow that is ventilated, and these open / close dampers can be partially opened and closed independently. Therefore, when the processing wind speed of each electrostatic precipitator varies, the processing wind speed of each electrostatic precipitator can be finely adjusted and made uniform by partially opening and closing the damper. Operation that maximizes the SPM removal rate (dust collection efficiency), which is the original purpose of the electrostatic precipitator, can be realized.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan layout view of an electric dust collection system having a total processing air volume of 240 m ³ / s according to the present embodiment.

The tunnel exhaust gas on the roadway is guided to the electric dust collection system by a ventilation fan (not shown). In this electric dust collection system, three electrostatic precipitators 11 (processing air volume 40 m ³ / s) with high processing air speed are arranged in parallel with four electrostatic precipitators 12 (processing air volume 30 m ³ / s) with low processing air speed. ing. A NO ₂ reduction catalyst, a NO ₂ adsorbent, or a NO ₂ absorbent 13 is disposed on the downstream side of the electrostatic precipitator 12 as a NO ₂ removal unit. The dust collection efficiency of the electrostatic precipitator 11 having a high processing wind speed is 80%, and the dust collection efficiency of the electrostatic precipitator 12 having a low processing wind speed is also 80%. Accordingly, a dust collection efficiency of 80% is also achieved in the entire electric dust collection system. Both the electrostatic precipitator 11 having a high processing wind speed and the electrostatic precipitator 12 having a low processing wind speed are positive discharge types. Now, assuming that the average NO ₂ concentration on the inflow side is 0.1 ppm, when the total processing air volume is 240 m ³ / s, it is calculated that 24 cc of NO ₂ flows into the electric dust collection system. Table 6 summarizes the balance of the inflow side NO ₂ total amount and the outflow side NO ₂ total amount. The increase rate shown in Table 5 is used for the total amount of NO _{2 at the} midpoint.

From Table 6, it can be seen that if the removal rate in the NO ₂ removal section is 31% or more, the total outflow side NO ₂ amount does not exceed the total inflow side NO ₂ amount. A minus discharge type electric dust collector may be used.

  FIG. 2 is a plan view of the electric dust collection system. An open / close damper 14 is provided on the inflow side of each electric dust collector.

  FIG. 3 is a layout plan view of the electric dust collection system. A state in which a high voltage generated by the high-voltage power supply 15 is connected to each electric dust collector (an electric dust collector 11 having a high processing wind speed and an electric dust collector 12 having a low processing wind speed) via a high-voltage wiring 16 is shown.

  FIG. 4 is a plan view of the electrostatic dust collection system. A state is shown in which the electric dust collector 11 having a high processing wind speed and the electric dust collector 12 having a low processing wind speed are partitioned by a partition wall 17 and a variable air volume ventilation fan 18 is disposed in each of the partitioned air paths. .

  FIG. 5 is a plan layout view of the electric dust collection system. A state in which a guide vane 19 is arranged on the upstream side of the electrostatic precipitator 11 having a high processing wind speed is shown. The position of the guide vane may be on the downstream side of the electrostatic precipitator 11 or on both the upstream side and the downstream side. In addition, although the electrical dust collector 11 with a quick process wind speed is used in the figure, you may use the electrical dust collector with a treatment wind speed slower than it.

FIG. 6 is a plan layout view of the electric dust collection system. A NO ₂ reduction catalyst, NO ₂ adsorbent or NO ₂ absorbent 13 is disposed downstream of the electrostatic precipitator 11 having a high processing wind speed, and a member 20 having an equivalent pressure loss is also disposed in parallel. Yes. On the downstream side, the member 20 having a pressure loss equivalent to that of the NO ₂ reduction catalyst, the NO ₂ adsorbent, or the NO ₂ absorbent 13 may be arranged alternately, or in individual block units. It may be arranged at an arbitrary position.

FIG. 7 is a plan layout view of the electric dust collection system. A plurality of electrostatic precipitators 11 having a high processing wind speed are arranged in parallel, and a NO ₂ reduction catalyst or NO is provided on the downstream side of a part of the electrostatic precipitator 11 having a high processing wind speed among the plurality of fast electrostatic precipitators 11. ₂ , an NO ₂ absorbent 13, and an NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent disposed on the downstream side, and an electric dust collector 11 having a high processing wind speed, and a rear The electric dust collector 11 having a high processing wind speed, which is not arranged on the flow side, is partitioned by a partition wall 17, and a variable air flow type ventilation fan 18 for adjusting the processing air speed of the electric dust collector 11 having a high processing air speed is arranged in each system. ing.

FIG. 8 is a plan layout view of the electric dust collection system. A plurality of electrostatic precipitators 11 having a high processing wind speed are arranged in parallel, and a NO ₂ reduction catalyst or NO is provided on the downstream side of a part of the electrostatic precipitator 11 having a high processing wind speed among the plurality of fast electrostatic precipitators 11. ₂ adsorbents or NO ₂ absorbents 13 are arranged, and each electric dust collector is equipped with an open / close damper 14 for opening and closing the air flow to be ventilated, and these open / close dampers 14 can be partially opened and closed independently. is there.

  The present invention is an electric dust collection system capable of purifying nitrogen dioxide corresponding to the increase in nitrogen dioxide increased by an electric dust collector, and is suitable for purification of exhaust gas from a motorway tunnel.

Planar layout of electric dust collection system Planar layout of electric dust collection system Planar layout of electric dust collection system Planar layout of electric dust collection system Planar layout of electric dust collection system Planar layout of electric dust collection system Planar layout of electric dust collection system Planar layout of electric dust collection system Planar layout of electric dust collection system Planar layout of electric dust collection system

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Electric dust collector with fast processing wind speed 12 Electric dust collector with slow processing wind speed 13 NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent 14 Opening / closing damper 15 High voltage power supply 16 High voltage wiring 17 Bulkhead 18 Ventilation type ventilation fan 19 Guide vane 20 Member with equivalent pressure loss

Claims (10)

An electrostatic precipitator with a fast treatment wind speed and an electrostatic precipitator with a slow treatment wind speed are arranged in parallel, and a NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent is placed on the downstream side of the electrostatic precipitator with a slow treatment wind speed. Deployed electric dust collection system. The pressure loss of the NO ₂ reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent is equal to the difference between the pressure loss of the electrostatic precipitator with the fast processing wind speed and the pressure loss of the electrostatic precipitator with the slow processing wind speed The electric dust collection system according to claim 1, wherein: 3. The electrostatic dust collection system according to claim 1, wherein each electrostatic precipitator is provided with an open / close damper that opens and closes a flowing air flow, and the open / close damper is configured to be partially opened and closed independently. . 2. The high-voltage power supply for each electrostatic precipitator is constituted by a plurality of blocks, and the high-voltage power supply can partially apply a high voltage to each electric precipitator. Electric dust collection system in any one of -3. The electric dust collection system according to any one of claims 1 to 4, further comprising a control means capable of increasing or decreasing a corona discharge power of each electrostatic precipitator with a high voltage power source. 6. An electric dust collector having a high processing air speed and an electric dust collector having a low processing air speed are partitioned by a partition wall, and a variable air volume ventilation fan for adjusting the processing air speed of the electric dust collector is disposed in each system. The electric dust collection system in any one. A plurality of electrostatic precipitators are arranged in parallel, and a NO ₂ reduction catalyst, a NO ₂ adsorbent, or a NO ₂ absorbent is arranged on the downstream side of some of the plurality of electrostatic precipitators. upstream of electrostatic precipitator disposed to the downstream side of the _second reduction catalyst or NO ₂ adsorbent or NO ₂ absorbent, by placing the guide vanes, to be able to equalize the processing velocity of all the electrostatic precipitator Features an electric dust collection system. A plurality of electrostatic precipitators are arranged in parallel, and a NO ₂ reduction catalyst, a NO ₂ adsorbent or a NO ₂ absorbent is arranged on the downstream side of some of the plurality of electrostatic precipitators. An electric dust collection system in which a member having a pressure loss equivalent to that of a NO ₂ reduction catalyst, an NO ₂ adsorbent, or an NO ₂ absorbent is disposed on the downstream side of the remaining electric dust collector. A plurality of electrostatic precipitators are arranged in parallel, and a NO ₂ reduction catalyst, a NO ₂ adsorbent or a NO ₂ absorbent is arranged on the downstream side of some of the plurality of electrostatic precipitators. partition and electrostatic precipitator placed absorbent adsorbent or nO ₂ of the reduction catalyst or nO ₂ of nO ₂ in the downstream side after, not place them on the downstream side of the electrostatic precipitator by partition walls, each strain An electric dust collection system, characterized in that a variable air volume ventilation fan for adjusting the processing wind speed of the electrostatic precipitator is arranged on the front. A plurality of electrostatic precipitators are arranged in parallel, and a NO ₂ reduction catalyst, a NO ₂ adsorbent or a NO ₂ absorbent is arranged on the downstream side of some of the plurality of electrostatic precipitators, The electric dust collector is equipped with an open / close damper that opens and closes a flowing air flow, and the open / close damper has a structure that can be partially opened and closed independently.

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