ELECTROSTATIC AIR CLEANER

Abstract

An electrostatic air cleaner may include a corona charging stage, a precipitation stage, and an air mover (fan). The corona charging stage may include a first and second array placed under electrical potential difference capable of generating a corona discharge. The first array may be substantially parallel corona wires and may be located downstream of an air penetrable second array. The precipitation stage may be downstream from the corona charging stage. The spacing between the first array and the second array may be less than the distance of the precipitation stage to the second array. The air mover may be upstream of the corona charging stage or downstream of the precipitation stage or between these stages. The arrangement allows for higher ion output downstream of the first array with the same voltage and power consumption resulting in greater particle charging and better air cleaning efficiency.

Claims

1. An electrostatic air cleaner comprising: an ionizing stage including a first electrode array located in an airflow path and arranged to be air penetrable and a second electrode array arranged to be air penetrable located in said airflow path upstream from said first electrode array, wherein said first electrode array includes one or more ion emitting members; a precipitation stage located in said airflow path downstream of said ionizing stage and having at least a collecting electrode array; and a high voltage power supply connected between said first electrode array and said second electrode array having an output electrical potential between a corona onset voltage and a breakdown voltage of said first electrode array and said second electrode array.

2. An electrostatic air cleaner comprising: an ionizing stage including a first electrode array located in an airflow path and arranged to be air penetrable and a second electrode array arranged to be air penetrable located in said airflow path upstream from said first electrode array, wherein said first electrode array includes one or more ion emitting members; a precipitation stage located in said airflow path downstream of said ionizing stage and having at least a collecting electrode array; and a high voltage power supply connected between said first electrode array and said second electrode array having an output electrical potential between a corona onset voltage and a breakdown voltage of said first electrode array and said second electrode array; and where the first electrode array is located at a first distance from said second electrode array; and said precipitation stage is located at a distance from said first electrode array that is at least 1.5 times greater than the first distance.

3. The electrostatic air cleaner according to claim 1, where the first electrode array is at an electrical potential no greater than a safe electrical potential for humans.

4. The electrostatic air cleaner according to claim 1, where the first electrode array is under positive electrical potential relative to the second electrode array.

5. The electrostatic air cleaner according to claim 1, where the first electrode array comprises thin electrically conductive wires.

6. The electrostatic air cleaner according to claim 1, where the second electrode array comprises electrically conductive air penetrable web.

7. The electrostatic air cleaner according to claim 1 wherein said second electrode array defines a second electrode array plane and wherein said second electrode array plane is orthogonal to said airflow path.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention will now be described by way of example, with reference to and as shown in the accompanying drawings.

[0022] FIG. 1 shows a schematic of an electrode configuration in an electrostatic air cleaner.

[0023] FIG. 2 shows a schematic representation of art ions concentration in an electrostatic air cleaner as described herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Before the present invention is described in further detail, it is to be understood that the invention is not limited to the particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0025] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0026] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, a limited number of the exemplary methods and materials are described herein.

[0027] It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

[0028] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed.

[0029] FIG. 1 shows a schematic of an electrostatic air cleaner 100 with a charging stage and a precipitation stage. The charging stage includes a first array 102 and a second array 101. The second array 101 may be an air penetrable mesh and the first array 102 may be wires. The second array 101 may be an exciting electrode set. The first array 102 may be a corona electrode set. A potential difference of several kilovolts or greater may be applied by a high voltage power supply 108 between the first array and the second array. The first array 102 may be under positive electrical potential, in one example, in a range between 10 kV and 20 kV. The second array 101 is usually grounded. The electrical potential applied between these arrays should be substantial and at a level between the corona onset voltage and the breakdown voltage.

[0030] A fan (not shown) may also be part of the air cleaner 100 and may blow air in the direction depicted by the arrow 106.

[0031] The precipitation stage may include one or more collecting electrodes 104 and one or more repelling electrodes 105. Usually the collecting electrodes 104 are grounded and the repelling electrodes 105 are under high voltage potential of the same polarity as the voltage applied to the first array 102.

[0032] Any electrical potential may be applied to each of these electrodes providing that the potential difference between them is substantial enough to draw charged particles away from the repelling electrodes 105 toward the collecting electrodes 104. The repelling electrodes 105 are usually under positive electrical potential, for example, in the range from 5 kV to 15 kV. The repelling electrodes 105 may be connected to the first array 102 directly or via an electrical resistor (not shown).

[0033] Ions emitted from the first array 102 travel, under the influence of an air mover such as a fan, toward the precipitation stage and settle on the dust particles in the air. These particles become electrically charged and enter the area between the collecting 104 and repelling 105 electrodes.

[0034] The more ions are in the air between the first array 102 and the precipitation stage, the greater the chances that they encounter dust particles and charge them.

[0035] FIG. 2 schematically shows ions 201 blown by the fan toward the precipitation stage 202. The ion count and number of dust particles charged are increased and thereby collection efficiency of the electrostatic air cleaner is increased.

[0036] In an experiment comparing ion counts at an output of a precipitator where the collector stage air velocity and inlet particle count was held constant the respective ion counts at the outlet are given for two charging stage configurations. The first charging stage configuration had an electrode geometry as shown in FIGS. 1 and 2 namely a row of equally-spaced parallel grounded wires and a second row of equally-spaced parallel corona wires offset from the grounded wires. The distance between the two rows was 20 mm. The spacing between grounded wires was 15 mm and the spacing between corona wires was 20 mm.

[0037] The second charging stage configuration had an electrode geometry corresponding to U.S. Pat. No. 6,251,171, specifically a first row of equally-spaced parallel grounded wires having a spacing of 10 mm per wire followed by a row of equally-spaced parallel corona wires. The row of corona wires was arranged 20 mm from the first row of grounded wires. The spacing between corona wires was 20 mm and the corona wires were offset from the first row of grounded wires. A second row of ground wires was spaced 20 mm from the row of corona wires. The second row of ground wires were parallel and equally-spaced with 15 mm between each.

[0038] All grounded wires were of the diameter equal to 2 mm and all corona wires were of the diameter 0.1 mm.

[0039] The experiment was performed using corona voltages as shown in each case with an output ion count downstream of the ionizing stage. Table 1 shows the results using the second electrode configuration corresponding to the configuration geometry shown in U.S. Pat. No. 6,251,171.

TABLE-US-00001 TABLE 1 Ions count *10.sup.3/cm.sup.3 Voltage at the outlet 13.9 0 14 1.7 14.5 11 15 16 16 23 17 29 18 34 19 43 20 47

[0040] Table 2 shows the results using the first electrode configuration described above.

TABLE-US-00002 TABLE 2 Ions count Voltage *10.sup.3/cm.sup.3 12.5 3 13 8 14 86 14.5 100 15 115 16 140 17 152 18 180 19 198 20 >200

[0041] The ion count in Table 1 is dramatically lower than the ion count shown in Table 2. Table 1 shows that the maximum ion count at the output at the ionizer was only about 47,000 ions per cubic centimeter.

[0042] The collecting efficiency of the electrostatic air cleaner shown in Table 1 is measured at a level between 80-85% for the particles in the range between 0.3-5 microns.

[0043] The experimental results shown in Table 2 amount to approximately a 5-fold increase in the number of ions at the output of the ionizer. At a corona voltage of 20 kV the ion count was more than 200,000 per cubic centimeter.

[0044] The collecting efficiency of the electrostatic air cleaner shown in the Table 2 is measured at a level above 99% for the particles in the range between 0.3-5 microns.

[0045] The techniques, processes and apparatus described may be utilized to control operation of any device and conserve use of resources based on conditions detected or applicable to the device.

[0046] The invention is described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.

[0047] Thus, specific apparatus for and methods of the present invention have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the disclosure. Moreover, in interpreting the disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.