EP0769325A1 - Plaque de raptage des cendres pour séparateurs électrostatiques - Google Patents

Plaque de raptage des cendres pour séparateurs électrostatiques Download PDF

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Publication number
EP0769325A1
EP0769325A1 EP96830535A EP96830535A EP0769325A1 EP 0769325 A1 EP0769325 A1 EP 0769325A1 EP 96830535 A EP96830535 A EP 96830535A EP 96830535 A EP96830535 A EP 96830535A EP 0769325 A1 EP0769325 A1 EP 0769325A1
Authority
EP
European Patent Office
Prior art keywords
ash
fins
walls
capture
capture plate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP96830535A
Other languages
German (de)
English (en)
Inventor
Antonio Notarstefano
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Enel SpA
Original Assignee
Enel SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Enel SpA filed Critical Enel SpA
Publication of EP0769325A1 publication Critical patent/EP0769325A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/34—Constructional details or accessories or operation thereof
    • B03C3/40—Electrode constructions
    • B03C3/45—Collecting-electrodes
    • B03C3/51—Catch- space electrodes, e.g. slotted-box form

Definitions

  • the present invention relates to a new type of ash capture plate for electrostatic precipitators which is able, because of its particular design, to increase the efficiency of the removal of the ash thus reducing its emission into the environment.
  • Known electrostatic precipitators are metallic structures composed of channels that are travelled by the flue gas. Such channels are composed of parallel plates (capture electrodes) between which groups of wires are placed (emitting electrodes) parallel to one another and to the plates. The plates are electrically connected to one other and to the ground of the precipitator which, in turn, is connected to the earth wiring.
  • the wires are electrically connected to one another and are brought, usually, to a negative voltage with respect to the ground by means of a high-voltage power supply.
  • the first area close to the emitting electrodes, is subjected to a high intensity electric field and the corona effect, which causes the ionization of the surrounding gas and the attachment of the ions to the ash particles entrained by the flue gas, occurs therein.
  • the second area comprised between the boundary of the first area and the capture plates, houses a lower intensity electric field in which the charged particles are made to move.
  • This motion is such that it overlaps with the component of motion related to the flow of the flue gas, the resultant motion causing the ash particles to deposit on the capture electrodes where they gather in a layer as a result of cohesive forces of electrostatic nature as well as adhesive forces of chemical-physical nature.
  • the plates are periodically shaken to remove the layer of ash deposited on them.
  • the detached ash falls under the force of gravity into collection hoppers placed in the lower part of the precipitator.
  • a precipitator is subdivided into several stages arranged in series called sections. When high flow rates of gas must be handled, it is formed by several parallel rows of sections.
  • the parameter characterizing the electrostatic precipitators is the capture efficiency which is defined by the one-complement of the ratio between the mass of the ash per Nm 3 of gas at the outlet and at the inlet of the precipitator.
  • the leakage can be defined as the part of ash deposited on the intercepting surface of the section which undergoes a detachment from the plates and is captured by the next sections or is released into the environment, rather than being removed by means of precipitation into an underlying hopper as a consequence of a cleaning action.
  • the cause of such leakage can be found in the erosion by the same dusty and turbulent gas on the progressively aggregated layer of ash.
  • the erosion caused by the gas increases also as a function of electric parameters and phenomena relating to the layer, such as the resistivity value of the particulate, the micro-discharges within the layer and the occasional discharges between the electrodes, said parameters being further correlated to the chemical-physical properties of the ash.
  • the leakage becomes gradually greater as the thickness of the layer increases, in such a manner that the periodic removal of the ash from each section by means of the shaking of the plates becomes essential.
  • this action causes leakage produced by the turbolent motion of the gas and by the fact that the shaking also produces vibrations perpendicular to the plane tending to fracture the layer of ash, thus facilitating the entrainment of the pulverized particulate by the flow of gas.
  • known electrostatic separators are equipped with specially profiled plates which are mounted in an alternating manner with conventional plates on each row, making it possible to act against the erosion on 50 % of the capture surfaces.
  • the general object of the present invention is to improve the capture efficiency of industrial electrostatic precipitators.
  • a particular object of the present invention is to provide a new structure of capture plate for electrostatic precipitators suitable to reduce the important phenomenon of carrying-over of the ash and to make possible a better operation of the electric power supply.
  • the ash capture plate according to the present invention which is formed of a box-like body with two extended main walls delimiting a channel-shaped chamber, at least one of the two walls having a plurality of windows spaced from one another, from an edge of each window extending an inclined fin, bent toward the inside of said chamber and constituting the capture surface of the plate along with the portions of the surface of said wall delimited by said windows.
  • the ash capture plate according to the present invention is formed of a substantially flat box-like body 1, i.e. with its longitudinal and transverse dimensions many times greater than its thickness, comprising two extended main walls la and 1b, which, in use, are lapped by the gas flow F, and two edge members lc which connect said walls, defining between them a channel-shaped chamber 2 of a substantially rectangular cross-section.
  • a plurality of transversal cuts or windows 3 are formed parallel to and spaced from one another which have an elongated rectangular cross-section and are delimited by two main edges 3a and 3b i.e. the longer sides (figure 3).
  • each window 3 a fin 4 extends from walls 1a and 1b inside chamber 2, said fin being inclined by a certain angle with respect to walls la and 1b.
  • each fin 4 extends from one of the two edges of corresponding window 3.
  • windows 3 formed on one of the walls of the capture plate are not aligned with windows 3 formed on the other wall. Consequently, inside chamber 2, fins 4 extending from one wall are staggered with respect to those extending from the facing wall. This allows for the distance between the free ends of two opposite fins to be kept to the highest value while maintaining the same inclination between them, and thus makes it possible to define a median channel inside chamber 2 and between the fins which provide minimum resistance to the flow during their discharge, due to gravity, of the ash that has accumulated on the fins.
  • two distinct capture areas are defined in it: a vertical area 4a composed of the portion of surface of walls 1a and 1b comprised between two adjacent windows 3, and an inclined area 4b inside chamber 2 composed of the surfaces of fins 4 facing the corresponding windows 3.
  • edge 3a of the side opposite that from which the corresponding fin 4 extends is advantageously rounded to prevent the presence of sharp edges that would cause excessive intensity of the electric field in proximity to the surface of the plates, thus bringing about undesired discharge phenomena.
  • FIG 4 a variation of the capture plate according to the invention is shown in which fins 4 extend from only one of the two walls, for example wall 1b, whereas the other wall ld is solid.
  • This variation creates two embodiments of the plate, a "right side” and a “left side” plate respectively, to be used in each section respectively to form the first row of plates to the left with respect to the direction of gas flow and the last row of plates to the right with respect to the same direction of gas flow with the purpose of avoiding accumulation of ash on the side walls of the precipitator.
  • the capture plate according to the invention works in the following manner.
  • the particulate, electrically charged by the ions produced by the corona effect migrates under the action of the electric field towards the plates of opposite polarity forming a layer which deposits both on the vertical interception area 4a as well as on the broader surface of fins 4b.
  • the ash deposited on the fins is protected to a large extent from the erosive action of the gas stream and, furthermore, the particulate that may be removed by the fins is in any case confined to the inside of the three-dimensional structure of the plate, precipitating inside it within the hopper.
  • the capture plate according to the invention can be conventionally realized by pairing two U-shaped semiplates along the entire length of the short sides of the U, uniting the two elements by welding them at a few points on both the adjacent sides.
  • the fins can be welded in correspondence with each window or, more simply, can be cut from walls 1a and 1b in the formation step of the windows and bent toward the inside.
  • the inclination of fins 4 can vary from 10° to 50° with respect to the wall of the plate from which they extend. An angle of 30° was found to be a particularly advantageous angle of inclination of the fins.
EP96830535A 1995-10-20 1996-10-17 Plaque de raptage des cendres pour séparateurs électrostatiques Withdrawn EP0769325A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT95FI000216A IT1278776B1 (it) 1995-10-20 1995-10-20 Piastra per la captazione delle ceneri per precipitatori elettrostatici
ITFI950216 1995-10-20

Publications (1)

Publication Number Publication Date
EP0769325A1 true EP0769325A1 (fr) 1997-04-23

Family

ID=11351398

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96830535A Withdrawn EP0769325A1 (fr) 1995-10-20 1996-10-17 Plaque de raptage des cendres pour séparateurs électrostatiques

Country Status (2)

Country Link
EP (1) EP0769325A1 (fr)
IT (1) IT1278776B1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107812612A (zh) * 2016-09-14 2018-03-20 东莞市宇洁新材料有限公司 微通道结构颗粒物集尘器、集尘方法及其制作方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE438972C (de) * 1923-11-30 1927-01-05 Siemens Schuckertwerke G M B H Niederschlagselektrode fuer elektrische Gasreinigung

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE438972C (de) * 1923-11-30 1927-01-05 Siemens Schuckertwerke G M B H Niederschlagselektrode fuer elektrische Gasreinigung

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107812612A (zh) * 2016-09-14 2018-03-20 东莞市宇洁新材料有限公司 微通道结构颗粒物集尘器、集尘方法及其制作方法
CN107812612B (zh) * 2016-09-14 2020-05-15 东莞市宇洁新材料有限公司 微通道结构颗粒物集尘器、集尘方法及其制作方法

Also Published As

Publication number Publication date
IT1278776B1 (it) 1997-11-28
ITFI950216A0 (fr) 1995-10-20
ITFI950216A1 (it) 1997-04-20

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