Dielectric barrier electrostatic precipitator
By coating the anode plate with a low-conductivity dielectric layer to form a dielectric barrier electric field, combined with a conventional electric field, the problem of low removal efficiency of conductive dust in existing electrostatic precipitators is solved, achieving ultra-low emission requirements, reducing retrofit costs and energy consumption, and is suitable for fields such as coal-fired flue gas, alumina, steel, and cement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 浙江菲达环保科技股份有限公司
- Filing Date
- 2024-01-15
- Publication Date
- 2026-07-31
AI Technical Summary
Existing electrostatic precipitators are ineffective at removing conductive dust with a resistivity of less than 10³ Ω·m, resulting in low dust removal efficiency, easy equipment damage, and high cost and energy consumption of existing retrofit technologies, which cannot meet ultra-low emission requirements.
The dielectric barrier electrostatic precipitator uses a low-conductivity dielectric layer coated on the anode plate to form a dielectric barrier electric field. Combined with a conventional electric field, it achieves efficient capture of conductive dust, reduces energy consumption, and has wide adaptability, suitable for fields such as coal-fired flue gas, alumina, steel, and cement.
It achieves efficient removal of conductive dust with a resistance of less than 10³ Ω·m, reducing equipment costs and energy consumption. It is highly adaptable and can achieve ultra-low emissions with an outlet particulate matter concentration of less than 10 mg/m³, making it suitable for retrofitting existing equipment.
Smart Images
Figure CN117816377B_ABST
Abstract
Description
[Technical Field]
[0001] This invention relates to the technical field of flue gas pollutant treatment and electrostatic precipitators, and in particular to a dielectric barrier electrostatic precipitator. [Background Technology]
[0002] Electrostatic precipitators are environmentally friendly equipment used to remove particulate matter from industrial flue gas. They can significantly reduce dust emissions and are one of the important means of solving air pollution.
[0003] Statistics show that the market for upgrading and retrofitting electrostatic precipitators (ESPs) will exceed 5 billion yuan in the next two to three years. While the market for ESP retrofitting is huge, there is still a lack of cost-effective and efficient ESP retrofitting technologies. On the other hand, my country's ultra-low emission policy has expanded from coal-fired power plants to the entire industry. The "Opinions on Promoting the Implementation of Ultra-Low Emissions in the Steel Industry," jointly issued by five ministries, stipulates that the maximum limit for particulate matter emission concentration in flue gas from steel sintering machines and pellet roasting is 10 mg / m³. 3 Currently, the dust concentration at the outlet of electrostatic precipitators for steel sintering machines is generally 25-50 mg / m3, which can no longer meet the requirements of existing ultra-low emission policies. As of December 2022, 41 out of 144 steel companies surveyed by the China Iron and Steel Association had completed ultra-low emission retrofits. It is expected that by 2025, more than 80% of steel production capacity will have completed ultra-low emission retrofits. However, a large number of sintering machine heads have not yet completed ultra-low emission retrofits. Therefore, it is urgent to develop new electrostatic precipitator technologies to reduce the dust concentration at the outlet to below 15-20 mg / m3.
[0004] Conventional electrostatic precipitators cannot be used for conductive dust with a resistivity lower than 10³ Ω·m. This is because the charge on the conductive dust is immediately released after adsorption onto the anode plate, preventing it from adhering effectively and causing it to easily detach from the collector and re-enter the airflow, resulting in secondary re-entrainment and reduced dust removal efficiency. While filtration-based dust collectors such as metal mesh dust collectors, ultra-clean electrostatic bag filters, and coupled electrostatic bag filters can remove low-resistivity (highly conductive) dust, they suffer from drawbacks such as high resistance, high cost, and secondary pollution of the filter bags. Electrostatic removal of low-resistivity dust is difficult. The lower the resistivity of the dust, the smaller the resistance per unit length, resulting in a greater impact on the electric field and weaker electric field penetration, thus affecting the efficiency of the electrostatic precipitator. Therefore, problems arise such as low collection efficiency, susceptibility to internal short circuits, and easy damage to the insulation layer. Currently, the problem of low dust removal efficiency can only be alleviated by increasing the electric field voltage or increasing the electrode distance, but this only provides partial relief and increases the size of the electrostatic precipitator. [Summary of the Invention]
[0005] The purpose of this invention is to solve the problems in the prior art and propose a dielectric barrier electrostatic precipitator that is low in cost, improves dust removal efficiency, is widely adaptable to the modification of existing equipment, is reliable in operation, has low energy consumption, and is well applicable to the removal of particulate matter from flue gas in the fields of coal combustion, alumina, steel, and cement. In particular, it overcomes the technical limitation of existing electrostatic precipitators that cannot remove conductive dust, and can achieve ultra-low emission requirements with an outlet particulate matter concentration of less than 10 mg / m3.
[0006] To achieve the above objectives, the present invention proposes a dielectric barrier electrostatic precipitator, comprising a housing, wherein an inlet end cap and an outlet end cap are respectively provided at the front and rear ends of the housing, and a dielectric barrier electric field is provided inside the housing, wherein the dielectric barrier electric field comprises several rows of dielectric barrier anode plates and several rows of corona wires I arranged alternately, wherein the dielectric barrier anode plates are composed of anode plates I coated with a barrier medium on both sides.
[0007] Preferably, the blocking medium is a dielectric layer with low conductivity.
[0008] Preferably, the low-conductivity dielectric layer is glass, epoxy resin, or polytetrafluoroethylene.
[0009] Preferably, the thickness τ of the barrier medium is 0.8 mm to 5.0 mm.
[0010] Preferably, the distance d between the same poles of the dielectric barrier electric field is 250mm to 400mm.
[0011] Preferably, the middle section of the anode plate I is provided with a blocking medium of different thicknesses, wherein the blocking medium coating is thicker at the position corresponding to the needle of the corona wire I, and thinner at other positions, and the transition position with different coating thicknesses is a gradual arc transition.
[0012] Preferably, a conventional electric field is also included, located inside the housing and in front of the dielectric barrier electric field.
[0013] The beneficial effects of this invention are as follows: This invention, by constructing a dielectric barrier anode plate consisting of an anode plate I coated with a barrier medium on both sides, achieves high operating voltage and uniform spatial current, effectively capturing particles that are extremely difficult to charge. Compared with existing technologies, it offers lower costs, improved dust removal efficiency, broad adaptability to existing equipment modifications, reliable operation, and low energy consumption. It is well-suited for removing particulate matter from flue gas in industries such as coal combustion, alumina, steel, and cement. In particular, it overcomes the technical limitation of existing electrostatic precipitators in removing conductive dust, enabling ultra-low emission requirements with an outlet particulate matter concentration of less than 10 mg / m3.
[0014] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. [Attached Image Description]
[0015] Figure 1 This is a schematic diagram of the structure of a dielectric barrier electrostatic precipitator according to the present invention;
[0016] Figure 2 This is a schematic diagram of the dielectric barrier anode plate.
[0017] Figure 3 It uses the principle of dust collection through dielectric barrier electric field.
[0018] In the figure: 1-shell, 2-inlet end cap, 3-outlet end cap, 4-dielectric barrier electric field, 5-conventional electric field, 41-dielectric barrier anode plate, 42-corona line I, 411-blocking dielectric, 412-anode plate I.
Detailed Implementation Methods
[0019] See Figure 1 , Figure 2 and Figure 3 The present invention discloses a dielectric barrier electrostatic precipitator, comprising a housing 1, wherein an inlet end cap 2 and an outlet end cap 3 are respectively provided at the front and rear ends of the housing 1, and a dielectric barrier electric field 4 is provided inside the housing 1. The dielectric barrier electric field 4 includes several rows of dielectric barrier anode plates 41 and several rows of corona wires I42 arranged alternately. The dielectric barrier anode plates 41 are composed of anode plates I412 coated with a barrier dielectric 411 on both sides.
[0020] The blocking medium is a dielectric layer with low conductivity.
[0021] The low-conductivity dielectric layer is glass, epoxy resin, or polytetrafluoroethylene.
[0022] The thickness τ of the barrier medium is 0.8 mm to 5.0 mm. The material and thickness of the barrier medium are determined based on the characteristics of the dust, the composition of the coal and ash, emission requirements, and power supply configuration.
[0023] The spacing d between the same poles of the dielectric barrier electric field 4 is 250mm to 400mm.
[0024] The anode plate I412 has a blocking medium 411 of different thicknesses in the middle section. The blocking medium 411 coating is thicker at the position corresponding to the needle of the corona wire I42, and thinner at other positions. The transition position with different coating thickness is a gradual arc transition. Different thicknesses can achieve uniform spatial current density, and the arc transition can reduce processing difficulty and cost.
[0025] It also includes a conventional electric field 5 located inside the housing 1 and in front of the dielectric barrier electric field 4.
[0026] The conventional electric field 5 consists of several rows of alternating anode plates II51 and several rows of corona wires II52.
[0027] The standard anode plate is a C-shaped anode plate, made entirely of 304 stainless steel or SPCC material.
[0028] Working process of this invention:
[0029] In the operation of the dielectric barrier electrostatic precipitator of the present invention, the front-end electric field is a conventional electric field 5 (1-5 electric fields), and the final electric field is a dielectric barrier electric field 4 (1-2 electric fields).
[0030] Dust-laden flue gas is evenly introduced into various channels of the electrostatic precipitator through the inlet end cap 2. After the flue gas and dust are charged, most of the particles are adsorbed onto the anode plate II and captured under the action of the electric field force of the front-end electric field. The remaining particles that cannot be captured enter the dielectric barrier electric field 4 with the airflow. The particles are charged and captured under the high voltage of the dielectric barrier electric field 4, thereby achieving the ultra-low emission requirement of 10mg / m3.
[0031] The reason for the high dust removal efficiency of the dielectric barrier electric field is as follows: One of the "particles that cannot be captured" mentioned above is that conventional electrostatic precipitators cannot use conductive dust with a resistivity lower than 10³ ohms. This is because the charge on the conductive dust is immediately released after it is adsorbed onto the anode plate II, thus failing to adhere effectively and escaping directly back into the flue gas. However, the dielectric barrier electric field 4 has a dielectric layer with relatively low conductivity. When charged dust is adsorbed onto the dielectric barrier anode plate I41, the charge cannot be directly released, thus the electric field force remains, avoiding the aforementioned problem.
[0032] Reason 2 for the high dust removal efficiency of dielectric barrier electric fields: Experiments show that the spatial current density distribution in conventional electric fields is uneven, and there may even be a corona shielding zone. However, the dielectric barrier electric field 4 changes the spatial electric field distribution because of the dielectric barrier. By arranging the barrier dielectric, a uniform spatial current density is achieved, thereby realizing effective spatial charging of dust and improving dust removal efficiency.
[0033] Dielectric barrier electric field dust collection principle: The surface of the anode plate I412 of the dielectric barrier electric field is coated with a certain thickness of barrier dielectric. The barrier dielectric is not easy to conduct electricity. Due to the presence of the barrier dielectric, the anode plate I412 and the corona wire I42 are isolated by the space for flue gas flow and the barrier dielectric. Compared with the conventional electric field, the secondary voltage around the corona wire I42 is higher and the current density is lower.
[0034] Particulate matter that escapes through a conventional electric field or metal filter is generally difficult to charge. For example, particles containing high levels of aluminum oxide or silicon dioxide are difficult to charge and are not easily captured by conventional electrostatic precipitators. The escaped particles enter the dielectric barrier electric field 4 set in the final electric field. Due to the ultra-high secondary voltage of the dielectric barrier electric field 4, the particles that are difficult to charge are forced to charge under the ultra-high voltage, and are thus captured and removed by the dielectric barrier electric field 4.
[0035] Regarding energy consumption: The energy consumption of an electrostatic precipitator can be simplified as P = V × A = V × S × б. Compared with a conventional electric field, the secondary voltage V of the dielectric barrier electric field is increased, but the plate current density б is decreased. Therefore, considering that the base area S required for the dielectric barrier electric field to achieve the same outlet particulate matter concentration is lower, the overall energy consumption P of the dielectric barrier electric field can be significantly reduced.
[0036] The method for modifying a conventional electrostatic precipitator to a media barrier electrostatic precipitator includes the following steps:
[0037] 1. Replace all conventional anode plates II in the final electric field with dielectric barrier anode plates 41 (the electric field using dielectric barrier anode plates is a dielectric barrier electric field), and coat the surface of conventional anode plates II with a barrier dielectric.
[0038] 2. Adjust the spacing between the same poles of the final electric field (dielectric barrier electric field);
[0039] 3. Adjust the high voltage power supply. The rated secondary voltage of the high voltage power supply for the dielectric barrier electric field is 80kV (the rated secondary voltage of the ordinary high voltage power supply for the conventional electric field is generally 72kV). The high voltage power supply type is a high-frequency power supply or a pulse power supply with pulse function.
[0040] 3. The control system of the media barrier electrostatic precipitator is characterized by:
[0041] 1. The secondary voltage and secondary current can be adjusted according to the characteristics of the dust. When the conductive dust has a low specific resistance, the secondary voltage is reduced.
[0042] 2. The high-voltage power supply of the front-end conventional electric field and the high-voltage power supply of the back-end dielectric barrier electric field have a linkage function.
[0043] This application has the following advantages:
[0044] 1. The pressure drop is below 250Pa, the equipment resistance is low, and the fan design requirements and operating energy consumption are low.
[0045] 2. The blocking medium of the anode plate is small in quantity, has a long service life, and the secondary pollution is almost negligible.
[0046] 3. It can achieve electrostatic dust removal of conductive dust with a resistivity of less than 10³, especially metal powder.
[0047] 4. The dielectric barrier electric field only requires replacing the anode plates of the original electrostatic precipitator or coating them with a barrier medium. It is highly applicable to retrofit projects, has low cost, no site requirements, and does not increase equipment resistance.
[0048] 5. The dielectric barrier electric field has a high operating voltage (secondary voltage), which can force charge and remove extremely difficult-to-charge particles, resulting in high dust removal efficiency, especially for PM2.5 particles that are extremely difficult to remove.
[0049] 6. The dielectric barrier electric field has a low operating current (secondary current), resulting in low power consumption during equipment operation and energy saving while reducing emissions.
[0050] 7. The dielectric barrier electric field operates with a uniform current, which can uniformly charge the flue gas particles in the space, resulting in high particle charging efficiency and low energy waste.
[0051] 8. The conventional electric field and the dielectric barrier electric field are effectively combined. By setting the conventional electric field at the front end and the dielectric barrier electric field at the end, particles of different sizes and compositions are removed in a graded manner, so as to maximize the dust removal performance.
[0052] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the scope of protection of the present invention.
Claims
1. A dielectric barrier electrostatic precipitator characterized by: The device includes a housing (1), with an inlet end cap (2) and an outlet end cap (3) at the front and rear ends of the housing (1), and a dielectric barrier electric field (4) inside the housing (1). The dielectric barrier electric field (4) includes several rows of dielectric barrier anode plates (41) and several rows of corona lines I (42) arranged alternately. The dielectric barrier anode plates (41) are composed of anode plates I (412) coated with barrier medium (411) on both sides. The middle section of the anode plates I (412) is provided with barrier medium (411) of different thicknesses. The barrier medium (411) coating is thicker at the position corresponding to the needle of the corona line I (42), and thinner at other positions. The transition position with different coating thicknesses is a gradual arc transition.
2. The dielectric barrier electrostatic precipitator as described in claim 1, characterized in that: The blocking medium is a dielectric layer with low conductivity.
3. The dielectric barrier electrostatic precipitator as described in claim 2, characterized in that: The low-conductivity dielectric layer is glass, epoxy resin, or polytetrafluoroethylene.
4. The dielectric barrier electrostatic precipitator as described in claim 1, characterized in that: The thickness τ of the barrier medium is 0.8 mm to 5.0 mm.
5. The dielectric barrier electrostatic precipitator as described in claim 1, characterized in that: The distance d between the same poles of the dielectric barrier electric field (4) is 250mm ~ 400mm.
6. A dielectric barrier electrostatic precipitator as described in any one of claims 1 to 5, characterized in that: It also includes a conventional electric field (5) located inside the housing (1) and in front of the dielectric barrier electric field (4).