Device and method for purifying gases

The present invention relates to a device for purifying gases comprising a filter container in which a flow space is formed for the gas to be cleaned, at least one arranged in the flow space discharge electrode and at least one arranged in the flow space precipitation electrode, wherein by applying a voltage between the discharge electrode and the precipitation particles of the gas to be purified on the precipitation electrode to be deposited.

There are known electric filters in which a negative discharge electrode, and a deposition electrode are provided in an electric field. By applying a high voltage particles are charged and deposited on the deposition electrode. In such electrostatic precipitators there is a problem that on one hand the degree of separation is limited and other, contaminating the deposition electrode and thus the filtering performance is impaired. A mechanical cleaning is usually associated with considerable effort and is not always possible.

It is therefore an object of the present invention to provide an apparatus for cleaning of gases having a high filter efficiency and is easy to clean.

This object is achieved with a device having the features of claim 1.

According to the deposition electrode is designed as flowed through conductive filter material for mechanical filtration of particles. This ensures that the gas to be cleaned flows through the permeable filter material and thus the distance between the particles and the precipitation electrode is extremely low, so that the cleaning power is increased. The filtering can be improved by combining a mechanical filtering and filtering by the principle of the electrostatic precipitator. To clean only the permeable filter material the precipitation must be cleaned.

In contrast to the known electric filters, the separation electrodes are flowed through from conductive materials from the gas to be cleaned and in particular pneumatic purified by backwashing at the novel electrostatic precipitators. The separation electrodes or filter elements can be made of multi-ply tissues, nonwovens, porous materials or dumped. Preferably, the separation electrodes or filter elements from stainless steels are produced

Preferably, the precipitation electrode includes a conductive fabric filters and / or a conductive non-woven filter on or reproduced by other porous / throughflow bare conductive materials of granules or chips, are conceivable The separation electrodes / filter elements may be made of metal, in particular stainless steel, can be made. Thus, the deposition electrode can be even at high temperatures, in particular for the purification of flue gases employ. The filter material may be made of fibers, granules or chips having a thickness of less than 2 mm or 0.5 mm, in particular less than 0.3 mm. Such fibers, wires, pellets or chips can be processed into a filter material whose mesh size or pore size less than 2mm, in particular less than 0.6 mm, for example less than 0.3 mm, so that even smaller particles are already filtered mechanically.

The filter material may comprise multiple layers with a conductive filter fabric and / or a conductive non-woven filter. The layers may have different or same permeability to gases. The permeability can be reduced from the outside inwards. The layers may consist of similar or different mesh size for example of wire mesh.

The filter material preferably has a thickness of more than 2mm, in particular between 5 mm and 30 mm. Thereby, the gas to be purified is passed through a thick filter material to which there is a deposition of the particles.

According to another embodiment of the invention, the filter material may be tube-, pocket-shaped or dome-shaped. For this purpose, the filter material on the deposition electrode dimensionally stable supporting bodies such as baskets to be held to assume a defined position within the flow chamber. The production of self-supporting filter elements is conceivable, for example from an intrinsically rigid wire mesh. This allows both the function of the electrostatic filter and the cleaning can be optimized.

For the cleaning preferably an injection of a cleaning gas is used in counter-current operation. The flow chamber is traversed by the gas to be cleaned in a first direction in the area of ​​the filter material, the filter material can be traversed by a purge gas, contrary to this direction of flow in a second direction, to remove any loose and collected on the filter material deposited particles in a pneumatic cleaning can be. This leads to the advantage that once-separated particles are not conducted during the cleaning operation by the flow space to the clean gas side, but again in the space in which the raw gas is present. Such pneumatic cleaning may take place at regular intervals, an automatic cleaning is possible. Such cleaning can be carried out simultaneously for all the baghouse, envelope or hood-shaped filter elements in the flow space, or even for individual subgroups of filter elements.

The baghouse, envelope or dome-shaped filter elements can be held vertically hanging or lying horizontally or cantilevered or arranged at an angle between vertical and horizontal in the flow space. Preferably, the filter elements are at an angle between 15 ° and 45 °, in particular arranged is deflected about 30 ° from the vertical. The flow through the raw gas is designed so that a falling flow is realized in the filter housing (downflow principle).

Further, in the flow chamber at a distance from the tubular separation electrodes a plurality of discharge electrodes arranged in the form of Sprühdrähten. The discharge electrodes may be taut between insulators in the flow chamber and at a defined distance, for example between 3 cm and 30 cm, spaced are provided by the separation electrodes. The discharge electrodes may in this case be parallel to the longitudinal axis of the filter elements, or even oriented at an angle to, in particular perpendicular.

The inventive device for cleaning of gases is particularly suitable for the cleaning of hot gases, especially flue gases, especially when the filter material is produced from a filter cloth or a filter fleece made of metal. The gases may include a temperature greater than 100 ° C, in particular greater than 200 ° C, but if necessary, temperatures of about 300 or about 400 ° C. The use is possible at ambient temperature.

The invention will be explained in more detail using an exemplary embodiment with reference to the accompanying drawings. Show it:<dl id="dl0001"><dt>figure 1</dt><dd>a schematic view of an inventive device for purifying gases, and</dd><dt>figure 2</dt><dd>a sectional view through the apparatus of the <figref idrefs="f0001">figure 1</figref>,</dd></dl>

A device 1 for cleaning of gases comprises a filter container 2, to which an inlet 3 is formed on a gas to be cleaned. In the filter container 2 a flow chamber 4 is formed, in which a plurality of emission electrodes and separation electrodes 20 5 is arranged. The separation electrodes 5 are formed as flowed through the filter material, in particular a filter fabric and / or a filter fleece, granules or chips from an electrically conductive material. metallic materials are preferably used for the filter material used, for example, stainless steel. The filter material may be made of fibers, wires, granules or chips having a thickness of 0.1 to 2 mm, in particular between 0.1 mm and 0.2 mm. The thickness of the filter material is preferably in a range between 2 mm and 30 mm, wherein the filter material can be arranged one or several layers, in particular 2 to 15 plies may be used of filter material. When a lattice-shaped filter material, for example a filter cloth, is used, the mesh width in a range between 0.2 mm and 10 mm, in particular 1 mm to 5 mm.

The separation electrodes 5 of the filter material are formed hose-, pocket-or dome-shaped and are flowed through from the outside of the gas to be purified. The separation electrodes 5 are designed to be closed on its underside, while they are stored hanging on its upper side at an intermediate wall 7 in the filter container 2 on a tubular holder. 8 The tubular separation electrodes 5 will thus flow through from outside to inside, wherein the purified gas flows through the tubular holder 8 to an outlet 6 to the filter container 2nd

Spaced from the separation electrodes 5 are a plurality of discharge electrodes 20 provided in the form of Sprühdrähten which are each positioned between the insulator 21 and the insulator 22 taut and spaced from the separation electrodes 5, for example at a distance between 1 cm and 30 cm, in particular 3 cm to 10 cm. The insulator 21 may be fixed via a holder 24 to the intermediate wall 7, while the insulator 22 is fixed to a holder 23 which is fixed to the filter container 2nd

Thus, the separation electrodes remain 5 arranged in flow-through condition in a predetermined position in the flow chamber 4, the separation electrodes are 5 with the filter material held on dimensionally stable support bodies, for example, to baskets, where the filter material is fixed. This movement is relative to the discharge electrodes 20 are largely avoided.

In order to purify the separation electrodes 5, above the tubular holder 8, a cleaning tube 9 is provided are provided in the nozzle 10, the opening to the tubular holders is directed eighth Through the nozzle 10, a cleaning gas can thus in the individual tubular -, pocket- or hood-shaped precipitation electrodes 5 are blown, the cleaning gas is opposite to the flow direction of the gas to be cleaned is blown through the filter material. By the cleaning process, the deposited particles are collected on the separation electrodes 5 to a funnel 11 at the bottom of the filter container 2 and disposed of via a rotary vane 12 or other means.

The cleaning gas is fed into the cleaning tube 9 through a pressure vessel 13 which is charged via a compressor fourteenth As cleaning gas can be used for example air, a controller 15 is provided to repeat the cleaning process at specific intervals. This can be carried out via lines 16 and 17 pressure measurements to determine the pressure in the filter container 2 on the clean gas side and the raw gas and thereby detecting a possible clogging degree. Also other parameters can be used for the controller 15 for cleaning. Through the sudden injection of a cleaning gas through the cleaning tube and the nozzles 10 5 adhering particles can be blown against the flow direction of the precipitation, so they are collected in the hopper 11th The pressure and the volume of the injected purge gas can be selected depending on the size of the separation electrodes 5 and the filter container 2nd

In <figref idrefs="f0002">figure 2</figref> is a horizontal section shown through the filter container 2, which has the inlet 3 at one side with the gas to be purified. In the flow chamber of the filter housing 2, a plurality of tube-, pocket- or hood-shaped precipitation electrodes 5 is disposed of filter material hanging, which are surrounded by several discharge electrodes 20 in the form of Sprühdrähten. Between the discharge electrodes 20 and the separation electrodes 5, a voltage source 25 is arranged, which is connected via a line 26 to the individual discharge electrodes 2 and a line 27 to the separation electrodes 5, which is shown only schematically. Thereby an electric potential between the discharge electrodes 20 and the separation electrodes 5 is formed, which may for example be in a range between 6 kV and 80 kV, in order to achieve a high degree of separation of electrically charged particles.

The inventive device 1 is particularly suitable for the cleaning of hot gases, especially flue gases, temperatures between 250 ° C and 500 ° C may have, for example in biomass incinerators Syntesegasreaktoren or internal combustion engines, for example, ship or large diesel engines. Other areas of application in the area of ​​gas cleaning are possible.

LIST OF REFERENCE NUMBERS

<dl id="dl0002" compact="compact"><dt>1</dt><dd>device</dd><dt>2</dt><dd>filter container</dd><dt>3</dt><dd>inlet</dd><dt>4</dt><dd>flow space</dd><dt>5</dt><dd>precipitation electrode</dd><dt>6</dt><dd>outlet</dd><dt>7</dt><dd>partition</dd><dt>8th</dt><dd>holder</dd><dt>9</dt><dd>cleaning pipe</dd><dt>10</dt><dd>nozzle</dd><dt>11</dt><dd>funnel</dd><dt>12</dt><dd>rotary</dd><dt>13</dt><dd>pressure vessel</dd><dt>14</dt><dd>compressor</dd><dt>15</dt><dd>control</dd><dt>16</dt><dd>management</dd><dt>17</dt><dd>management</dd><dt>20</dt><dd>spray electrode</dd><dt>21</dt><dd>insulator</dd><dt>22</dt><dd>insulator</dd><dt>23</dt><dd>holder</dd><dt>24</dt><dd>holder</dd><dt>25</dt><dd>voltage source</dd><dt>26</dt><dd>management</dd><dt>27</dt><dd>management</dd></dl>