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CN-121988455-A - Method and device for removing condensable particles by coupling acoustic agglomeration and charge retention

CN121988455ACN 121988455 ACN121988455 ACN 121988455ACN-121988455-A

Abstract

The application belongs to the field of pollution control and deep purification of flue gas, and particularly discloses a method and a device for removing condensable particles by coupling acoustic agglomeration and charge retention, wherein the method comprises the steps of forcedly inducing CPM components in high-humidity flue gas to collide and agglomerate at high speed by utilizing a sound field to enable CPM to rapidly form agglomerated particles, and then carrying out charge compensation on the coagulated particles under the condition of high-humidity flue gas so as to inhibit rapid decay of the surface charges of the particles, ensuring that the coagulated particles keep effective mobility in a subsequent trapping electric field, and finally capturing and removing the coagulated particles with stable charges by utilizing the trapping electric field. The removal method utilizes a sound field to promote the condensation and growth of gaseous precursors such as acid mist cores, superfine liquid drops, suspended inorganic salts, SO 3 /NH 3 and the like, ensures the rapid migration, adhesion and sedimentation of the condensation particles in an external electric field through charge retention, realizes the efficient removal of superfine CPM, and avoids the risk of CPM regeneration and re-release caused by liquid drop entrainment, interface nucleation and airflow disturbance under the conditions of high humidity or local supersaturation.

Inventors

  • LIU XIAOWEI
  • ZOU YUE
  • XU MINGHOU

Assignees

  • 华中科技大学

Dates

Publication Date
20260508
Application Date
20260227

Claims (10)

  1. 1. A method for removing condensable particulates by acoustic agglomeration and charge retention coupling, comprising: under the condition of high-humidity flue gas of a WFGD and/or WESP outlet section, utilizing the sound field effect to induce the condensable particles in the high-humidity flue gas to collide and agglomerate at a high speed, so that the condensable particles are converted into condensed particles with discontinuous liquid phase interfaces and low charge rapid decay characteristics; Performing charge retention treatment on the coagulated particles to compensate for charge decay of the coagulated particles and ensure mobility of the coagulated particles in an externally applied electric field; and carrying out electric field migration, capturing and removing on the coagulated particles subjected to charge compensation treatment by utilizing a capturing electric field.
  2. 2. A device for removing condensable particles by acoustic agglomeration and charge retention coupling, which is arranged on a flue of a WFGD and/or WESP outlet section, characterized in that the device for removing the condensable particles comprises: the sound wave aggregation module (10) is arranged in the flue and close to the inlet of the flue so as to form a sound wave aggregation section (50) in the flue, and the sound wave aggregation module (10) can generate a sound field for inducing high-humidity smoke in the flue so as to enable CPM components generated and continuously generated in the high-humidity smoke to collide and aggregate at a high speed in the sound wave aggregation section and form aggregation particles suitable for subsequent charge retention treatment; A charge retention module (20), the charge retention module (20) being disposed within the flue downstream of the acoustic agglomeration module (10) to form a charge retention section (51) within the flue, the charge retention module (20) being configured to charge-retain the agglomerated particles so that the agglomerated particles retain an effective amount of charge sufficient for electric field migration in a high humidity flue gas environment; The device comprises a flue, a trapping electric field module (30) and a gas flow control module, wherein the trapping electric field module (30) is arranged at the bottom of the flue and is continuously arranged along the flue to form a bottom trapping belt, and the bottom trapping belt forms a particle trapping section (52) in the flue; And the acoustic agglomeration section (50), the charge holding section (51) and the particle trapping section (52) are sequentially connected along the flow direction of the flue gas in the flue.
  3. 3. The condensable particulate removal device of claim 2, further comprising a feedback adjustment device (40), the feedback adjustment device (40) configured to monitor in real time flue gas parameters of the high humidity flue gas in the channel and operating parameters of the sonic agglomeration module (10), the charge retention module (20), and the trapping electric field module (30), and to achieve dynamic coordinated control of acoustic source output, corona discharge, and electric field strength by feedback adjustment.
  4. 4. The device for removing condensable particles according to claim 2, wherein the acoustic wave agglomeration module (10) comprises an acoustic source array (11), an acoustic field coupling structure (12) and an acoustic field control unit, the acoustic source array (11) is arranged on the side wall of the flue and is used for forming an acoustic field action area covering the cross section of the flue at the installation position, the acoustic field coupling structure (12) is used for directionally coupling acoustic energy output by the acoustic source array (11) into the flue, and the acoustic field control unit is used for adjusting the frequency, the sound pressure level and the phase of the acoustic source so as to enable the acoustic field action area to adapt to different types of condensable particles.
  5. 5. The device according to claim 4, wherein the sound source array (11) is one or a combination of two or more of an opposed type, a matrix type or a circumferential arrangement type, the sound field coupling structure (12) comprises at least one of a sound waveguide, a sound cavity or a sound beam shaping plate, and a corrosion-resistant protective layer is provided on an inner wall of the sound field coupling structure (12).
  6. 6. The condensable particulate removal device according to claim 2, wherein the charge holding module (20) comprises a corona electrode (21), a counter electrode (22), an ion diffusion region (23) and a power supply control unit, the corona electrode (21) is in a needle, wire or needle-line combined structure, the counter electrode (22) is in a plate-type or tube-type structure, electrode materials of the corona electrode (21) and the counter electrode (22) are both corrosion-resistant conductive materials, a corona discharge region is formed between the corona electrode (21) and the counter electrode (22), the ion diffusion region (23) is arranged at the downstream of the corona discharge region and used for prolonging an effective diffusion path of ions in flue gas, and the power supply control unit is used for applying an operating voltage to the corona electrode (21) so as to maintain a discharge state.
  7. 7. The condensable particulate removal device of claim 6, wherein the charge retention module (20) operates at a voltage ranging from 3kv to 8kv and at a current ranging from 0.1ma to 3ma.
  8. 8. The condensable particulate removal device of claim 2, wherein the trapping electric field module (30) includes a dust collecting plate (31), a discharge electrode (32), a power supply device (33), and an insulating support structure (34); The electric field collecting device comprises a dust collecting pole plate (31) and a discharge electrode (32), wherein a collecting electric field area is formed between the dust collecting pole plate (31) and the discharge electrode (32) and is used for applying electric field force to charged coagulated particles, a power supply device (33) is used for applying voltage required by a collecting place between the dust collecting pole plate (31) and the discharge electrode (32), and an insulating supporting structure (34) is used for supporting the dust collecting pole plate (31), the discharge electrode (32) and the power supply device (33).
  9. 9. The condensable particulate removal device of claim 8, wherein the polarity of the dust collection plate (31) is consistent with a charge sign imparted to the coagulated particles by the charge retention module (20).
  10. 10. The device for removing condensable particles according to claim 8, wherein the electric field trapping module (30) is provided with a liquid draining structure, and the liquid draining structure is arranged at the bottom of the dust collecting polar plate (31) and is used for timely draining liquid or semi-liquid particles deposited on the surface of the dust collecting polar plate (31).

Description

Method and device for removing condensable particles by coupling acoustic agglomeration and charge retention Technical Field The application belongs to the technical field of pollution control and deep purification of flue gas, and particularly relates to a method and a device for removing condensable particles by acoustic agglomeration and charge retention coupling. Background Currently, coal-fired power plants have been widely equipped with pollution control devices in combination with systems to achieve ultra-low emission targets of conventional pollutants, such as filterable particulates, sulfur dioxide, nitrogen oxides, and the like. Condensable particulates, defined as liquid or solid particulates (typically <2.5 μm) that are in the gaseous state in the flue and are released to the atmosphere upon cooling condensation or reaction. Because the generation mechanism is complex, and is particularly strongly related to SO 3, VOCs, aerosol, superfine liquid drops and gas-liquid interface reaction, condensable particles (Condensable Particulate Matter, CPM) are difficult to remove by the conventional flue gas pollution control device. Studies have shown that the CPM occupancy to the atmosphere is significantly higher than filterable particulate matter under ultra low emission conditions. In fixed source ultra low emission systems, wet Flue Gas Desulfurization (WFGD) and wet electrostatic dust collection (WESP) are commonly regarded as end-point purification units in flue gas remediation processes. Under typical running conditions, the flue gas is in a high humidity or even local supersaturation state, and liquid drops, steam and a gas-liquid interface coexist continuously, so that a stable environment is provided for acid mist nucleus formation, superfine liquid drop enrichment and secondary nucleation. In addition, the high humidity environment is easy to cause rapid decay of the surface charge of the particles, so that the mobility of the particles at the outlet section of the wet electric dust collector is obviously reduced, and the difficulty of capturing the tail ends is aggravated. However, recent practical studies have shown that the WESP outlet CPM concentration of some coal-fired units is rather higher than that of the inlet, exhibiting a "negative removal" phenomenon. The phenomenon is caused by multiple mechanisms such as liquid drop entrainment and fragmentation, SO 3/NH3/H2 O interface nucleation, volatile element enrichment, superfine acid mist migration limitation and the like, and in addition, the high-humidity environment easily causes rapid decay of the surface charge of the particles, SO that the mobility of the particles at the outlet section of the wet electric precipitator is obviously reduced, and the difficulty in capturing the tail end is aggravated. The above shows that WFGD/WESP itself may become a regeneration zone for CPM, and it is difficult to structurally and mechanically avoid the risk of re-release of CPM, which is not a terminal purification device in the conventional sense. The prior art is mainly developed along the "enhanced" route of the existing wet process apparatus, i.e. improving the CPM removal capability by means of structural optimization, spray strengthening, absorbent modification or precursor abatement, etc. Although some progress has been made in the prior art in CPM precursor control, droplet agglomeration or aggregation path optimization, these techniques all rely on the basic physical environment of existing wet plants, i.e., vapor saturation, droplet presence, and gas-liquid mass transfer processes are required to achieve absorption, condensation, or aggregation effects. However, it is this highly humid or even locally supersaturated flue gas environment that significantly promotes secondary nucleation of SO 3/H2 O and sustained enrichment of ultrafine particles, making the wet section naturally have dynamic conditions that produce new CPM. Thus, it is difficult to avoid structural risks of CPM regeneration of WFGD/WESP end segments, either in placement or control mechanisms, and there is a lack of independent and targeted control means. Meanwhile, the prior art is largely improved in structure of the existing flue or wet equipment, the engineering quantity is large, the investment cost is high, and the modular reinforcement scheme which can be implemented under the condition of not changing the main structure of the device is generally lacking, so that the engineering feasibility of the terminal CPM deep treatment is further limited. In summary, in the prior art, because the high humidity and even supersaturated environment of the wet process device is generally relied on, the secondary generation and negative removal of the CPM in the wet section are difficult to avoid, and the terminal treatment technology which can be independent of the wet process saturated environment and can perform efficient removal on the generated and secondarily generated super