FR2516405A1 - EMISSION ELECTRODE ASSEMBLY FOR ELECTRO-FILTERS - Google Patents

Abstract

THE INVENTION RELATES TO A SET OF EMISSION ELECTRODES FOR ELECTRO-FILTERS. THE ASSEMBLY INCLUDES A RECTANGULAR FRAME IN WHICH PARALLEL ELECTRODES 6 ARE PLACED BETWEEN ITS UPPER AND LOWER PARTS, THE FRAME BEING SHAPED OF A TUBE OF RECTANGULAR SECTION THE HEIGHT H IS GREATER THAN ITS WIDTH 1, SO AS TO REDUCE THE SET OF ELECTRODES FOR EMISSION IN THE VERTICAL DIRECTION WITHOUT INCREASING ITS THICKNESS; FURTHERMORE IT IS PROVIDED AT ONE END OF THE EMISSION ELECTRODES 6 A SPRING 10 AND A TIGHTENING NUT 11 TO KEEP THE ELECTRODE TENSIONED DESPITE DIFFERENCES BETWEEN THE THERMAL EXPANSION COEFFICIENTS OF THE ELECTRODE AND OF THE FRAME.

Description

The present invention relates to a set of electrodes

  for electro-filters, and it relates more specifically to

  to a set of emission electrodes which comprises a substantially rectangular frame optionally provided with transverse and longitudinal stiffeners, and a plurality of parallel emission electrodes, usually formed of a wire and tensioned between the transverse stiffeners and / or the parts superior and

lower part of the frame.

  Such emission electrode assemblies are used in electrostatic precipitators to separate dust from a dust-laden gas, in which case several sets are provided.

  emission electrodes which are placed, considering the direc-

  flow, in the vertical position, and in

  In addition, each time, two sets of electro-

  adjacent transmitters, a set of precipitating electrodes,

  For the separation efficiency of the electro-filter, it is preferable that the emission electrodes and the adjacent precipitation electrodes are placed in positions as close as possible to each other but not sufficiently close together for the assemblies This is why the goal is to realize the framework of

  electrodes as narrow as possible.

  In order to remove the dust adhering to the emission electrodes, the electro-filter comprises striking devices by means of which the emission electrode assembly is subjected to shocks to remove dust adhering possibly to the electrodes of the electrodes. The percussion effect is all the more effective as the emission electrodes are more strained. For this reason, the emission electrodes are arranged with the maximum possible tension between the transverse stiffeners of the frame and / or the parts upper and lower part of this

  However, the upper and the lower part

  the frame are structurally as robust as possible

  ble, that is to say massive tubes were used to form the frame Si in this case it is desirable to increase the voltage of the emission electrodes, the diameter and the wall thickness of the upper and lower tubes However, this also increases the width of the frame, in which case the emission electrodes can no longer be mounted in positions as close to the precipitation electrodes as would be desirable in view of the size of the frame.

efficiency of the electro-filter.

  The temperature inside the electro-filter can vary very strongly. It is the lowest when it is necessary to carry out maintenance operations in the electrofilter.

  repair or cleaning and at its maximum value it may

  dye several hundred degrees Celsius If the frame and the

  son constituting the emission electrodes are formed of

  The wires forming the emission electrodes are usually made of a material having a coefficient of thermal expansion greater than that of the material forming the frame. emission electrodes tend to take slack at the elevated temperatures existing in the electro-filter, in which case cleaning them with the aid of

  striking devices becomes difficult or totally impossible.

  Due to the greater coefficient of thermal expansion,

  Because of the wires forming the emission electrodes, it would be advantageous to stretch them sufficiently in the frame so that, even during their elongation, they are sufficiently tight to be cleaned by means of a striking device. not possible without increasing the thickness of the frame structure so that the sets of emission and precipitation electrodes placed in adjacent positions are too much

away from each other.

  A known solution is to suspend weights at the lower end of the son forming the emission electrodes so as to keep them taut regardless of longitudinal expansion. However, with reasonably large weights, it is not possible to give In addition, these weights have a tendency to become detached and to cause obstructions and also to increase the weight of the filter. Because of the weights, the upper part of the frame must also be sufficiently robust. so that again the sets of precipitation electrodes and

  can not be mounted in positions that are sufficiently

closely related.

  The object of the invention is to overcome the disadvantages

  mentioned above and to provide a set of electrodes for

  mission for electro-filters, in which the thickness of the frame -2- -3- is very small but the structure is still sufficiently robust so that the emission electrodes can be sufficiently stretched for cleaning, and in which a variation of voltage due to a different coefficient of thermal elongation of the wires forming the emission electrodes can be compensated without increasing

  sensible weighting of the emission electrode assembly.

  This goal is achieved by the fact that the height of the

  cross-section of at least the upper part and the lower part

  the frame is larger than its width in order to reinforce

  said parts in the vertical direction.

  The present invention is therefore based on the idea that, by increasing the height of the cross section of the upper part and the lower part of the frame, these parts can be reinforced in the vertical direction without

  simultaneous increase in their width.

  emitting electrodes can be tightened more strongly

  than before without increasing the thickness of the frame.

  used for the frame is therefore, instead of the type of tube previously used, a tube having a section

  right oval that has a height greater than its width In varian-

  it is possible to use upper and lower parts having a rectangular cross-section. Also other forms of cross-section in which the height is greater than the

width are conceivable.

  To maintain the tension of the wires forming the electro-

  emissions approximately unchanged regardless of the

  temperature in the electro-filter and the long-term dilatation

  different longitudinal son forming the emission electrodes, it is possible to mount an elastic element to a tensioning element serving to tension the elastic element at a temperature lower than the

  service temperature at one end of the wires forming the elec-

  trode $ in order to maintain these strained wires despite

  their longitudinal dilation The opposite end of a wire-elec-

  trode is preferably fixed by welding to a transverse stiffener.

  versal or, there is no stiffener, on the

  opposite lower or upper part.

  Other advantages and characteristics of the invention

  will be highlighted in the following description, given in

  By way of nonlimiting example, with reference to the accompanying drawing in which: FIG. 1 is a perspective view of a set of emission electrodes according to the present invention, and FIG. 2 is a perspective view of FIG. the set of emission electrodes of FIG. 1 on an enlarged scale. In FIG. 1, the frame of the electrode assembly

  has been designated by references 1, 2 and 3.

  1 denotes the upper part of the frame, the reference 2 designates its lower part and the reference 3 designates its two lateral parts. The frame 1, 2, 3 has also been reinforced at

  with a transverse stiffener 4 and two longitudinal stiffeners

  The son forming the emission electrodes, which are designated 6, have been arranged parallel to the lateral portions 3 between the longitudinal stiffener 4 and respectively

  the upper part 1 and the lower part 2.

  Electro-filters usually have very large

  dimensions and, in such a case, the height of the elec-

  emission trodes can also be large, for example 10 meters Even if a small difference in thermal elongation between the side portions 3 and the son-electrodes 6 can

  cause in this condition a loosening of the wires-electro-

  when the temperature rises, if the coefficient of

  The thermal insulation of the material of the electrode wires is greater than that of the lateral parts 3 of the frame, or they are tight.

  so strongly that they can break, if the coefficient of

  In the first case, the dusts possibly adhering to the electrode wires can not be detached from them by means of electromechanical devices.

  of percussion that strike the set of electrodes

  when, in the latter case, the electrode wires can break, or the frame, and in particular its upper parts.

  1 and lower 2 can twist -

  As shown in more detail in Figure 2, this disadvantage can be avoided in part by using, in the frame structure, tubes of rectangular cross section, the height h of the tubes being greater than their width 1 In this case, the transverse stiffeners 4 and longitudinal 5 are preferably formed by tubes of the same profile The rigidity of such a frame in the vertical direction is considerably

-5 2516405

  larger than that of a frame made of symmetrical profile tubes

  consequently, the wires forming the electrodes of

  6 can be stretched more sharply than before without

  increasing the thickness of the elements i, 2, 3, 4, 5 of the frame.

  On the other hand, the release or the tension of the son forming the emission electrodes and the frame 1; 2, 3 because of the differences between the coefficients of thermal expansion and under the effect of variations in the temperature of the electro-filter, can be eliminated, or at least minimized, by fixing at least one end of the electrodes 6 by means of an elastic element 10 on the upper part 1 of the frame or on the lower part 2, respectively, as shown in more detail in FIG. 2. Each end of the emission electrode is preferably engaged in a constricted opening of the transverse stiffener 4 and in the upper part 1 or respectively the lower part 2, an end 8 of the emission electrode wire 6 being folded against the transverse stiffener 4 and being fixed thereto by On the other hand, the opposite end 7 of the emission electrode is provided with a thread on which a nut 1 i and a locking nut 12 can be screwed and res such that the spiral spring 10 provided between the nut 11 and the upper part 1 or the lower part 2, engaged through the end 7 of the transmission electrode wire 6, is compressed to lock the wire electrode The spiral spring 10 is completely compressed by means of the nut 11 when the coefficient of thermal expansion of the transmission electrode 6 is greater than that of the side portions 3 of the frame.

  temperature then increases during the operation of the elec-

  3-filter, the emission electrode-wire 6 elongates with respect to the frame and at this time the end of the transmission electrode wire 6 which is provided with the nuts Il and 12 is further away from the upper part 1 or in the lower part 2 In this case, however, the transmitting wire can not loosen

  because the spiral spring 10 continues to keep it taut.

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Claims (4)

  1 Set of emission electrodes for electro-   filters, having a substantially rectangular frame (1, 2, 3) optionally provided with transverse stiffeners (4) and longitudinal stiffeners (5), as well as a plurality of parallel emission electrodes (6) and arranged between the transverse stiffeners (4) and / or the upper (1) and lower (2) parts of the frame, characterized in that the height (h) of the cross section of at least the upper (1) and lower (2) parts of the frame is greater than its larggr (1) with a view to reinforcing   parts (1, 2) in the vertical direction.   2 Set of emission electrodes according to claim   cation 1, characterized in that at least the upper parts   Top (1) and bottom (2) of the frame have rectangular straight sections. 3 Set of emission electrodes according to one of   1 or 2, characterized in that it is provided   a spring and a clamping member (9) at least at one end   (7) of the emission electrode (6) to reinforce it at a temperature of   below the operating temperature of the electro-   filter in order to keep the emission electrode (6) thanks to its longitudinal dilatation.   4 Set of emission electrodes according to the claim   3, characterized by the fact that one end (7) of   transmission trodes (6) is provided with a thread and is engaged in a constricted opening of the upper part (1) or the lower part (2) of the frame (1, 2, 3), that the element of tightening is a nut (11) mounted on this threaded end and that the spring is a compressible spiral spring (10) disposed   between the nut (11) and the upper part (1) or the lower (2).   Set of emission electrodes according to any one   of claims 3 or 4, characterized in that   the opposite end (8) of the emission electrode (6) is also   engaged in a strangled opening in the   transverse stiffening (4) or the opposite part   upper (1) or upper (2) frame, being folded along   of said portion and optionally welded thereto.