Partitioned particle charge coagulation technology based on differential high-voltage pulse

Abstract

The invention discloses a partition particulate matter charge coagulation technology based on differential high-voltage pulses, which utilizes a single pulse high-voltage power supply to realize positive and negative pulse partition discharge, and overcomes the defects of low operation voltage, high energy consumption and poor charge effect of traditional direct-current high-voltage charge. A partition alternate arrangement mode and an adjustable polar plate spacing structure are used, so that the problem of single-region charged positive and negative charge neutralization interference is avoided, and meanwhile, the problems of poor corona charge effect of fine particulate matters and equal charge quantity regulation and control are solved; fine particles are charged by the bipolar multi-region pulse charging unit and then flow into the enhanced coagulation unit, and under the action of turbulence and coulombic force in fluid, the positive and negative heteropolar charged fine particles approach and are coagulated into large particles; the fine particles flow into the electrostatic dust collection device for collection after passing through the reinforced coagulation unit, and by means of the device and the method, the submicron particle removal effect can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrostatic dust removal, and in particular relates to a zoned particle charge coagulation technology based on differential high voltage pulses. Background Art

[0002] Electrostatic dust removal technology is one of the main technical means to reduce the emission of fine particulate matter in places such as coal-fired power plant exhaust gas, boiler combustion flue gas treatment and public areas. It has the advantages of high dust removal efficiency, long continuous operation cycle and no pollution. In the publications CN1603004A and CN105396441A, a method of direct current or pulsed electrocoagulation of particles is proposed, but the charged environment of the particles is a single channel, and the positive and negative charges generated by the discharge are easy to mix under the action of turbulence, resulting in the charge on the same particle being easily neutralized by the opposite charge, which is not conducive to the coulombic coagulation of particles. Single polarity charge control and equal amount of opposite polarity charge of particles, especially for the efficient charge coagulation of fine particles, still need to be solved.

[0003] The charging methods of fine particles include diffusion charging and field charging. For large-size particles (greater than 1μm), field charging is the main method, and for small-size particles (below 0.17μm), diffusion charging is the main method. Submicron particles (particle size below 1μm) have a small surface area and light weight, making it difficult to be fully charged, so the actual dust collection effect is not good. Traditional filtering dust removal methods such as multi-layer bag dust removal have good dust removal effects but have the disadvantages of large pressure drop and the need to replace bags regularly. Electrostatic precipitators with unipolar charge not only have difficulty charging fine particles, but also have difficulty in achieving the effect of condensing small particles into large particles for collection through Coulomb condensation due to the repulsion of like charges.

[0004] The electrocoagulation technology has the characteristics of low cost, high efficiency and good controllability. It is mainly divided into three types, namely the Coulomb collision coagulation of charged particles of opposite polarity, the collision coagulation of charged particles of the same sex promoted by the reverse electric field force of the alternating electric field, and the collision coagulation of charged particles of opposite sex promoted by the reverse electric field force of the alternating battery and the Coulomb force. Among them, the Coulomb coagulation of particles of opposite sex has a relatively good coagulation effect on particles and the lowest cost, but the heteropolar charging effect of particles before coagulation is particularly important. Although high-voltage pulse corona charging can solve the problems of low allowable operating voltage and poor single polarity charging effect of DC high-voltage discharge, how to obtain charged particles with equal charge during bipolar dual-zone pulse charging, and reduce the inter-particle coagulation resistance caused by the repulsion of residual charges during coagulation, so as to maximize the coagulation effect, has brought new challenges to the electrical characteristics of the output pulse high voltage of the power supply used, the discharge electrical structure design of the charging zone, and the layout of the charging zone. Summary of the invention

[0005] The present invention provides a zoned particle charging and coagulation technology based on differential high-voltage pulses. By using a differential high-voltage pulse power supply composed of a single synchronously output positive and negative nanosecond or microsecond pulse power supply, combined with multi-interval heteropolar pulse charging control, equal bipolar charging of fine particles can be achieved, which can solve the problem of insufficient coagulation effect of traditional submicron particles.

[0006] A zoned particle charging and coagulation technology based on differential high-voltage pulses, comprising a bipolar multi-zone pulse charging unit, an enhanced coagulation unit and an electrostatic dust collecting device connected in sequence;

[0007] The differential multi-zone pulse charging unit comprises a differential high-voltage pulse power supply and an even number of charging zones, wherein the number of positive and negative polarity charging zones is equal and arranged alternately, and each charging zone comprises a discharge electrode and a grounding electrode; the differential high-voltage pulse power supply is a single synchronously outputting positive and negative nanosecond or microsecond pulse power supply; the positive and negative high-voltage terminals of the power supply are respectively connected to the discharge electrodes of the positive and negative polarity charging zones, and are not connected to the grounding electrodes of the charging zones;

[0008] The enhanced condensation unit comprises a spoiler column and a porous flow equalizing plate;

[0009] The fine particles are charged by the bipolar multi-zone pulse charging unit and then flow into the enhanced condensation unit. Due to the change in the flow cross-sectional area, the flow velocity inside the main body of the airflow changes, causing turbulence and mixing inside the fluid. At the same time, the fine particles charged with positive and negative polarities approach each other under the action of Coulomb gravity, and the fine particles are condensed into large particles. After passing through the enhanced condensation unit, the fine particles flow into the electrostatic precipitator for collection.

[0010] Optionally, the discharge structure of the charging zone is a wire plate type or a wire cylinder type. The discharge electrode is a filament discharge electrode, a sawtooth discharge electrode or a multi-point discharge electrode; and the grounding electrode is a metal plate electrode or a metal cylinder electrode.

[0011] In the preferred technical solution, the discharge structure of the charging zone is a wire-bobbin type discharge structure, and the discharge electrode is a multi-tip discharge electrode. The multi-tip discharge electrode can reduce the operating voltage and energy consumption required for corona discharge, and the wire-bobbin type discharge structure can achieve the most uniform discharge effect in space.

[0012] Preferably, the pulse width of the differential high-voltage pulse power supply ranges from microseconds to nanoseconds, the voltage range is 0 to ±100 kV, and the discharge interval of the charging area is adjustable.

[0013] Further, the ground electrode of the charged area is grounded.

[0014] Furthermore, in the bipolar multi-zone pulse charging unit, the positive and negative polarity charges of the fine particles after being charged in each charging zone are almost equal.

[0015] Optionally, the spoiler column is in a triangular prism or an ellipse shape, and the spoiler column and the porous flow equalizing plate are made of metal or plastic.

[0016] Preferably, the porous flow equalizing plate is made of PP polypropylene, which has low material processing and manufacturing costs and good charge coagulation effect.

[0017] Preferably, the discharge electrode and the ground electrode in the charged area are both made of metal.

[0018] The aerodynamic diameter of fine particles is 0 to 10 μm. The types of particles to be treated include fly ash fine particles that escape because they are difficult to collect in industrial post-stage dust collectors, complex oxide aerosols condensed during boiler flue gas treatment, and fine particles existing in indoor and public areas.

[0019] The working principle of the present invention is as follows: the dust-laden airflow flows into the bipolar multi-zone pulse charging unit, and after being divided, it enters the staggered positive and negative polarity charging zones respectively. The charged electrodes in the charging zones generate a strong spatial electric field around the electrodes under the action of an external differential high-voltage pulse power supply, so that the air between the electrodes and the grounding plate is ionized into a corona plasma. The charged positive and negative polarity ions collide with the particles through Brownian motion or directional migration under the action of the electric field, so that the particles are charged. Finally, the particles in the negative polarity charging zone are mainly negatively charged, while the particles in the positive polarity charging zone are positively charged. The same polarity charging process can be regulated separately, and the dust-laden airflow after positive charging subsequently flows into the enhanced condensation unit. Under the action of the spoiler column, the airflows flowing out of the positive polarity charging zone are mixed with each other, and the particles with positive and negative charges collide with each other and condense into particles with larger particle sizes under the action of airflow mixing and Coulomb gravity.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention is based on the technology of charged coagulation of particles by using differential high-voltage pulse power supply. The bipolar charged zone is designed with adjustable discharge spacing and the use of differential high-voltage pulse power supply solves the problem of mismatch of particle charge caused by inconsistent output waveform of the charged power supply, large difference in peak voltage and phase, and inconsistent input power; the comprehensive use of triangular prism-shaped and elliptical prism-shaped spoiler columns in the enhanced coagulation unit reduces the cost of the coagulation device and has a good particle coagulation enhancement effect. By combining high-frequency pulse or composite pulse power supply corona discharge with electrostatic dust removal technology, efficient electrocoagulation and removal of submicron fine particles is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the process of a partitioned particle charge coagulation technology based on differential high voltage pulses of the present invention;

[0023] Figure 2This is a schematic diagram of the process of charging and condensing fine particles in two charging areas in Example 1 of the present invention;

[0024] Figure 3 It is a schematic diagram of the process of charging and condensing fine particles in four charging zones in Example 2 of the present invention.

[0025] In the figure: 1. Boiler; 2. Differential high-voltage pulse power supply; 3. Bipolar multi-zone pulse charging unit; 4. Enhanced coagulation unit; 5. Electrostatic precipitator; 6. Dust collection high-voltage power supply; 7. High-voltage transmission line; 8. Gas transmission pipeline; 9. Spoiler column; 10. Multi-porous flow equalizing plate; 11. Discharge electrode; 12. Grounding electrode; 13. Casing; 14. Triangular pyramidal spoiler column; 15. Multi-porous flow equalizing plate; 16. Grounding electrode; 17. Discharge electrode; 18. Cylindrical spoiler column; 19. Enhanced coagulation unit. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0027] like Figure 1 As shown, a zoned particle charging and coagulation technology based on differential high-voltage pulses includes a boiler 1, a bipolar multi-zone pulse charging unit 3, an enhanced coagulation unit 4 and an electrostatic precipitator 5 connected in sequence.

[0028] The differential high-voltage pulse power supply 2 provides high-frequency pulse high-voltage discharge to the bipolar charging zone in the bipolar multi-zone pulse charging unit 3 through the high-voltage transmission line 7. After being charged by the bipolar multi-zone pulse charging unit 3, the fine particles flow into the enhanced coagulation unit 4 through the gas transmission pipeline 8. The enhanced coagulation unit 4 includes a spoiler column 9 and a porous flow equalizing plate 10. After passing through the enhanced coagulation unit 4, the fine particles flow into the electrostatic precipitator 5 for collection. The dust collection high-voltage power supply 6 provides high-voltage discharge for the dust collection electrode in the electrostatic precipitator 5.

[0029] The differential high-voltage pulse power supply 2 can adopt a single synchronously output positive and negative nanosecond or microsecond pulse power supply.

[0030] Example 1

[0031] like Figure 2 As shown, the bipolar multi-zone pulse charging unit 3 includes a shell 13 and two charging zones (a positive polarity charging zone and a negative polarity charging zone) arranged in the shell 13, and the positive and negative polarity charging zones include a discharge electrode 11 and a grounding electrode 12.

[0032] In this embodiment, the discharge structure of the charging zone is a line plate discharge structure, and the differential high-voltage pulse power supply 2 is a single synchronously output positive and negative nanosecond or microsecond pulse power supply, which can output synchronous pulse high voltage in the voltage range of 0 to ±100kV from the positive and negative polarity high-voltage ends respectively, and the output frequency is adjustable from nanosecond to microsecond level. The positive and negative polarity ends of the high-voltage power supply are respectively connected to the sawtooth-shaped discharge electrodes 11 of the positive and negative polarity charging zones, and the grounding electrodes 12 of the two zones are grounded. By adjusting the voltage output to a suitable value, air corona discharge can be generated in the gap between the plates. Fine particles can be charged by introducing dust-laden airflow into the two charging zones. Adjusting the gas volume ratio introduced into the positive and negative polarity charging zones and the distance between the plates can change the charge amount of the two zones, and achieve the effect of equal charging of the particles in the two zones. After being charged by the bipolar multi-zone pulse charging unit 3, the fine particles flow into the enhanced coagulation unit 4 for particle electrocoagulation.

[0033] The enhanced condensation unit 4 includes a triangular pyramid spoiler column 14 and a porous flow equalizing plate 15. After flowing into the enhanced condensation unit 4, due to the change in the flow cross-sectional area, the flow velocity inside the main body of the airflow changes, causing turbulence and mixing inside the fluid. At the same time, the fine particles charged with positive and negative polarities approach each other under the action of Coulomb gravity to achieve fine particles condensation into large particles. After passing through the enhanced condensation unit 4, the particles flow into the electrostatic precipitator 5 for collection.

[0034] The principle of this embodiment is: the differential high-voltage pulse power supply 2 outputs positive and negative pulse high voltages with the same waveform but opposite polarities to the positive and negative polarity charged zone electrodes to induce air plasma corona discharge in the dual zones for efficient bipolar charging. The discharge distance between the two zones can be adjusted so that the fine particles can be charged equally therein. The condensation effect is then enhanced under the action of the triangular pyramidal spoiler column 14 and the porous flow equalizing plate 15 of polypropylene plastic to strengthen the airflow turbulence.

[0035] Example 2

[0036] like Figure 3 As shown, the bipolar multi-zone pulse charging unit 3 includes four charging zones, the number of positive and negative charging zones is equal and they are arranged alternately, and each charging zone includes a discharge electrode 17 and a grounding electrode 16.

[0037] The differential high-voltage pulse power supply 2 is a single synchronously output positive and negative nanosecond pulse power supply. The discharge electrode 17 is a multi-point cylindrical filament electrode, and the grounding electrode 16 is a metal cylindrical electrode.

[0038] The high-voltage output ends of the differential high-voltage pulse power supply 2 are respectively connected to the charged electrodes of the corresponding polarity charged zones as discharge electrodes. The power supply voltage range is adjustable from 0 to 100 kV, the pulse frequency range is from nanoseconds to microseconds, the discharge distance between the discharge electrodes 17 of the positive and negative polarity charged zones and the grounding electrode 16 is adjustable, and the grounding electrode 16 is grounded.

[0039] In this embodiment, the enhanced coagulation unit 4 includes a cylindrical spoiler column 18 .

[0040] The working principle of this example is: adjust the high voltage power supply of the bipolar charging zone to achieve positive and negative polarity gas corona discharge in the four zones, adjust the discharge voltage and the plate spacing and charging voltage to change the corona discharge intensity, and the particles flow into each charging zone and collide with the charged particles to carry positive and negative charges respectively. The particles charged with equal amounts of different polarities flow into the enhanced condensation unit 19 with the airflow, and the collision and condensation of fine particles with different charges in the airflow at the outlet of the staggered charging zones is enhanced. The dust-laden airflow after enhanced condensation can then enter the electrostatic dust collector to be collected.

[0041] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A technology for charged coagulation of partitioned particles based on differential high voltage pulses. It is characterized in that It comprises a differential multi-zone pulse charging unit (3), an enhanced coagulation unit (4) and an electrostatic dust collecting device (5) which are connected in sequence; The differential multi-zone pulse charging unit (3) comprises a differential high-voltage pulse power supply (2) and an even number of charging zones, wherein the number of positive and negative polarity charging zones is equal and arranged alternately, and each charging zone comprises a discharge electrode (11) and a ground electrode (12); the differential high-voltage pulse power supply (2) is a single synchronously output positive and negative nanosecond or microsecond pulse power supply; the positive and negative high-voltage terminals of the power supply are respectively connected to the discharge electrodes (11) of the positive and negative polarity charging zones, and are not connected to the ground electrodes (12) of the charging zones; The enhanced coagulation unit (4) comprises a spoiler column (14) and a porous flow balancing plate (15); After being charged by the bipolar multi-zone pulse charging unit (3), the fine particles flow into the enhanced condensation unit (4). Due to the change in the flow cross-sectional area, the flow velocity inside the main body of the airflow changes, causing turbulence and mixing inside the fluid. At the same time, the fine particles charged with positive and negative polarities approach each other under the action of Coulomb gravity, so that the fine particles are condensed into large particles. After passing through the enhanced condensation unit (4), the fine particles flow into the electrostatic precipitator (5) for collection.

2. According to claim 1, the partitioned particle charge coagulation technology based on differential high voltage pulse, It is characterized in that The pulse width of the differential high-voltage pulse power supply (2) ranges from microseconds to nanoseconds, and the voltage ranges from 0 to ±100 kV.

3. According to claim 1, the partitioned particle charge coagulation technology based on differential high voltage pulse, It is characterized in that The discharge electrode (11) is a filament discharge electrode, a sawtooth discharge electrode or a multi-point discharge electrode; the grounding electrode (12) is a metal plate electrode or a metal cylinder electrode.

4. According to claim 1, the partitioned particle charge coagulation technology based on differential high voltage pulse, It is characterized in that The discharge structures of the charging area include wire plate type and wire barrel type.

5. According to claim 1, the partitioned particle charge coagulation technology based on differential high voltage pulse, It is characterized in that The ground electrode (12) of the charged area is grounded.

6. According to claim 1, the partitioned particle charge coagulation technology based on differential high voltage pulse, It is characterized in that In the bipolar multi-zone pulse charging unit (3), the positive and negative polarity charges of the fine particles after being charged in each charging zone are almost equal.

7. According to claim 1, the partitioned particle charge coagulation technology based on differential high voltage pulse, It is characterized in that The spoiler column (14) is in the shape of a triangular prism or an ellipse, and the spoiler column (14) and the porous flow equalizing plate (15) are made of metal or plastic.

8. According to claim 1, the partitioned particle charge coagulation technology based on differential high voltage pulse, It is characterized in that The aerodynamic diameter of fine particles is 0 to 10 μm. The types of particles to be treated include fly ash fine particles that escape because they are difficult to collect in industrial post-stage dust collectors, complex oxide aerosols condensed during boiler flue gas treatment, and fine particles existing in indoor and public areas.

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