RU2189866C1 - Electric filter - Google Patents

Abstract

FIELD: dust trapping by means of corona discharge in electrostatic field, possibly in chemical, oil-chemical, metallurgical, machine engineering, mining, building and other industry branches, in ecology for cleaning flue gases and ventilation exhausts. SUBSTANCE: electric filter includes vertical housing, settling and corona discharge electrodes forming several electric fields, inlet and outlet gas ducts, hoppers and high voltage sources. In lower section of housing corona discharge electrodes are arranged crosswise relative to gas flow; in upper section - corona discharge electrodes are arranged along gas flow and they are provided with tube having lid of dielectric material. Said electrodes are mounted with possibility of their free axial motion by action of gas flow providing self-controlled electric current of corona discharge. Diameter of lid exceeds that of tube by (30-60)%. Outlet gas duct is cone one; it is flared in direction of gas flow. EFFECT: lowered electric energy consumption due to self-controlled corona discharge at change of gas flowrate. 1 dwg

Description

 The proposed technical solution relates to the field of dust collection using a corona discharge in an electrostatic field and can be used in chemical, petrochemical, metallurgical, engineering, mining, construction and other industries, as well as in environmental processes for cleaning flue gases and ventilation emissions.

 A known design of a plate electrostatic precipitator, including a housing with inlet and outlet ducts, between which plate-like precipitation electrodes are installed in the form of smooth metal sheets or grids stretched over the frames, between which corona electrodes made of wire segments are suspended (Machines and devices of chemical production. Third edition, revised and augmented. / Edited by II Chernobylsky.-M.: Mechanical Engineering. 1975. 451 p., p. 11-12).

 The reasons that impede the achievement of the desired technical result include significant energy costs for creating a stable corona discharge between the corona and precipitation electrodes, which leads to an increased cost of gas purification from the dispersed phase, especially with changes in gas flow.

 Known electrostatic precipitator for cleaning the gas stream from dust, including a housing with inlet and outlet pipes, precipitation electrodes, the elements of which are located across the gas stream at the inlet pipe and along the main part of the housing, and corona electrodes located between the rows of precipitation electrodes, while this is a free section in the rows of elements of precipitation electrodes located across the gas stream, it is 30-60% (ed. St. USSR 629981, B 01 D 35/06, B 01 C 3/09, electrostatic precipitator, 1978).

 The reasons that impede the achievement of the desired technical result include the complexity of the design of the electrodes, the elements of which are located across the gas flow at the inlet pipe, and significant energy costs for creating a stable corona discharge between the corona and precipitation electrodes, which leads to an increase in the cost of dust cleaning from changes gas flow rate.

 The closest technical solution chosen for the prototype is an electrostatic precipitator, consisting of a housing, sedimentation and corona electrodes, forming several electric fields, input and output flues, hoppers and high voltage sources, while one or more precipitation electrodes have cutouts, the planes of which are equipped with installed on insulators with plates grounded through the framework of measuring instruments, and installed at the beginning and end of the electrostatic precipitator (ed. St. USSR 1212490, B 01 D 35/06, B 03 C 3/09, electrostatic precipitator, 198 4).

 The reasons that impede the achievement of the desired technical result include increased energy costs due to the need to create a stable corona discharge between the corona and sedimentation electrodes in each electric field, which leads to an increase in the cost of cleaning gases from dust, especially when changing the gas flow.

 The objective of the proposed technical solution is to create a new design of an electrostatic precipitator, providing self-regulation of the corona discharge current with changes in the gas flow rate.

 The technical result is a reduction in energy consumption due to self-regulation of the corona discharge current when the gas flow rate changes.

 The technical result is achieved by the fact that in the electrostatic precipitator, consisting of a housing, sedimentation and corona electrodes, forming several electric fields, inlet and outlet ducts, hoppers and high voltage sources, the housing is vertical, in the lower zone of which the corona electrodes are installed across the gas stream, and in the upper zone, the corona electrodes mounted along the gas flow are equipped with a tube with a cap of dielectric material with the possibility of their free axial alternation scheniya under the action of the gas stream, providing self corona discharge current, the diameter of the lid the diameter of the tube by 30-60% and the output gas duct is conical with an extension in the direction of motion of the gas stream.

 Vertical installation of the housing and installation of corona electrodes in its lower zone across the gas stream allows charging the bulk of the dispersed phase of the gas stream due to corona discharge at the inlet of the electrostatic precipitator. Installing the corona electrodes in the upper zone along the gas stream and supplying each of them with a tube with a cap of dielectric material with the possibility of their axial movement under the action of the gas stream and making the diameter of the cap 30-60% larger than the diameter of the tube, and the outlet duct conical with an expanding cross section the direction of gas flow allows you to create an additional corona discharge and charge uncharged particles or droplets of the dispersed phase of the gas stream with an increase in its flow rate.

 With a decrease in gas flow rate, its dynamic effect on the tube cover decreases and it drops down, reducing the corona discharge current in the upper zone and reducing the energy consumption. The execution of the outlet duct conical with the expansion in the direction of gas flow allows increasing the working length of the corona electrodes with increasing gas flow, and decreasing it with decreasing gas flow, thereby ensuring self-regulation of the corona discharge current in the upper zone of the electrostatic precipitator.

 When reducing the diameter of the cap below the limit of 30% compared with the diameter of the tube, the dynamic effect of the gas flow on the cap is insufficient to lift the tube relative to the corona electrode. As the diameter of the cap increases above the limit of 60% compared with the diameter of the tube, the dynamic effect of gas flow on the cap becomes excessive, the tube rises and does not change its position with changes in gas flow.

 The drawing shows a diagram of the proposed design of an electrostatic precipitator.

 The electrostatic precipitator consists of a housing 1, vertical precipitation electrodes 2, made in the form of plates, between which corona electrodes 3 made of wire are installed. Sedimentary 2 and corona 3 electrodes form two or more electric fields (two electric fields are shown in the drawing). In the lower zone, the corona electrodes 3 are mounted across the gas stream. In the upper zone, the corona electrodes are installed along the gas stream.

 Each corona electrode 3 of the upper zone is equipped with a tube 4 with a cap 5, while the diameter of the cap 5 is 30-60% larger than the diameter of the tube 4. The tube 4 and the cap 5 are made of a dielectric material, for example polymer.

 For supplying dusty gas, an inlet duct 6 is installed in the lower part of the housing 1. For exhausting purified gas, an outlet duct 7 is made in the upper part of the housing, which is made conical with expansion in the direction of gas flow. To limit the lifting height of the tubes 4 installed height limiters 8.

 To connect the precipitation 2 and corona 3 electrodes to high voltage sources, the electrostatic precipitator is equipped with terminals 9.

 The electrostatic precipitator works as follows. High voltage wires from high voltage sources are connected to terminals 9. A dusty gas is fed through the inlet duct 6, which passes through the lower zone of the electrostatic precipitator with corona electrodes 3 and is ionized. Ions collide with dust particles, charge them and, together with the particles, move together with particles to precipitation electrodes 2. Some of the free (uncharged) and charged dust particles do not have time to settle on precipitation electrodes 2 in the lower zone of the electrostatic precipitator. They with a gas stream enter the upper zone of the electrostatic precipitator with corona electrodes 3.

 In order to save electricity, the corona current in the upper zone of the electrostatic precipitator flows only from the open part of the height of the corona electrodes 3, free of tubes made of dielectric material, since the latter prevents the formation of corona and current flow.

 Typically, the gas velocity is greatest on the axis of the apparatus. From the dynamic effect of the gas flow on the cover 5, the diameter of which is 30-60% greater than the diameter of the tube 4, the tubes 4 of the central corona electrodes 3 of the upper zone rise to a greater extent than the tubes 4 of the peripheral corona electrodes 3.

 The lifting of the covers 5 with tubes 4 is carried out until the force of the dynamic influence of the gas flow in the conical outlet duct 7 is balanced with the gravity of each tube 4 with the cover 5.

 Thus, the height of the open part of the corona electrodes 3 of the upper zone is proportional to the gas flow rate and decreases or increases with a decrease or increase in the gas flow rate in the gap between the precipitation electrodes 2. At low gas flow rates, the corona electrodes 3 are almost completely closed by tubes 4, the crown is not formed and additional current does not go. The main part of the particles is ionized and deposited in the lower zone with corona electrodes 3 mounted across the gas stream. Not having time to settle in this zone, charged particles are additionally deposited on the precipitation electrodes 2 in the upper zone, since the voltage on the precipitation electrodes is supplied even in the absence of a corona discharge on the corona electrodes 3.

 With an increase in gas flow, the tubes 4 with covers 5, according to the above mechanism, rise up, freeing part of the length of the corona electrodes 3 of the upper zone for corona discharge and current. In the limit, at the maximum gas flow rate, the tubes rise up to the stop in the bottom of the outlet gas duct 7 or height limiters 8.

 Thus, the proposed design of the electrostatic precipitator provides self-regulation of the corona discharge current due to a decrease in the crown height on the corona electrodes 3 of the upper zone with a decrease in gas flow or an increase in crown height with an increase in gas flow without measurement (as in the prototype design, auth. Of the USSR 1212490, 1984) dustiness of the air and signal transmission to the secondary voltage regulating device. This reduces energy costs by 30-50% with corresponding changes in gas flow through the electrostatic precipitator, simplifies maintenance and costs of voltage registration and regulation devices, and ultimately reduces the cost of gas purification in electrostatic precipitators.

 The proposed installation of tubes 4 with covers 5 of dielectric material on each corona electrode 3 of the upper zone is easy to carry out not only on newly constructed electrostatic precipitators, but also on those operating during their reconstruction.

Claims (1)

 An electrostatic precipitator, consisting of a housing, sedimentation and corona electrodes, forming several electric fields, inlet and outlet ducts, hoppers and high voltage sources, characterized in that the housing is vertical, in the lower zone of which the corona electrodes are installed across the gas stream, and in the upper zone, corona electrodes the electrodes mounted along the gas stream are equipped with a tube with a cap of dielectric material with the possibility of their free axial movement under the action of the gas stream, bespechivaet self corona discharge current, the diameter of the lid the diameter of the tube by 30-60% and the output gas duct is conical with an extension in the direction of motion of the gas stream.