Drying of filter elements in a filter system

Abstract

A filter system including a filter housing with an inlet part, a clean-gas outlet, and a partition wall defining a product chamber and a clean-gas chamber. The partition wall having openings from which filter elements extend downward into the product chamber. The inlet part is placed in an upper part of the product chamber and configured for supplying a product-containing flow of gas to the product chamber. The gas flow being conveyed through the filter elements and into the clean-gas chamber, where the filter system is provided with an air or gas supply placed in the product chamber and configured for leading drying air or gas into or out of the filter system. A method of drying filter elements in a filter system by passing drying air or gas through a filter inlet and/or through a drying air or gas supply.

Claims

1. A filter system, comprising: a filter housing comprising: an inlet for a product-containing gas, for the product-containing gas to be cleaned by filtering in a product-containing gas cleaning mode of the filter system; an outlet for cleaned gas; and a partition wall dividing the filter housing into a product chamber for the product-containing gas and a clean-gas chamber, wherein the partition wall is provided with a number of openings from which a plurality of filter bags extend downwards into the product chamber; wherein the inlet is placed in an upper part of the product chamber and in open communication with the product chamber, and configured for supplying the product-containing gas to the product chamber in the product-containing gas cleaning mode, wherein cleaning of the product-containing gas is accomplished by the product-containing gas flowing into insides of the plurality of filter bags and filtered gas from the plurality of filter bags flows upwards into the clean-gas chamber, from where the filtered gas is discharged through the outlet as clean gas; a source of drying air or gas; one or more drying air or gas supplies connected to the source of drying air or gas and having openings placed below the plurality of filter bags in a part of the product chamber and are configured for leading drying air or gas from below and up along sides of the plurality of filter bags after a wet cleaning mode of the filter system, wherein during the wet cleaning mode and prior to the filter system entering the product-containing gas cleaning mode, the plurality of filter bags are wet cleaned; and wherein the drying air or gas is for drying the plurality of filter bags.

2. The filter system according to claim 1, wherein the one or more additional drying air or gas supplies of the drying air or gas are placed at a level corresponding to a lower part of the plurality of filter bags.

3. The filter system according to claim 1, wherein the openings of the one or more drying air or gas supplies are placed around the lower part of the product chamber.

4. The filter system according to claim 1, wherein one or more of the one or more drying air or gas supplies is connected to the inlet.

5. The filter system according to claim 1, wherein one or more of the one or more drying air or gas supplies are closed by a closer during the product-containing gas cleaning mode and are opened after the wet cleaning mode.

6. The filter system according to claim 1, wherein an additional supply of the drying air or gas is configured to supply drying air or gas to the lower part of the product chamber through a discharge outlet for the product chamber.

7. The filter system according to claim 1, wherein an additional supply of the drying air or gas is configured to supply drying air or gas at a bottom of the filter housing.

8. The filter system according to claim 1, wherein the inlet is at a height that corresponds to a portion of the plurality of filter bags.

9. A method of drying a plurality of filter elements in a filter system, wherein the filter system comprises: a filter housing comprising: an inlet for a product-containing gas, for the product-containing gas to be cleaned by filtering in a product-containing gas cleaning mode of the filter system; an outlet for cleaned gas; and a partition wall dividing the filter housing into a product chamber for the product-containing gas and a clean-gas chamber, wherein the partition wall is provided with a number of openings from which a plurality of filter bags extend downwards into the product chamber; wherein the inlet for the product-containing gas is placed in an upper part of the product chamber and in open communication with the product chamber, and configured for supplying the product-containing gas to the product chamber in the product-containing gas cleaning mode, wherein cleaning of the product-containing gas is accomplished by the product-containing gas flowing into insides of the plurality of filter bags and filtered gas from the plurality of filter bags flows upwards into the clean-gas chamber, from where the filtered gas is discharged through the outlet for clean gas; a source of a drying air or gas; one or more drying air or gas supplies connected to the source of drying air or gas and having openings placed in a part of the product chamber below the plurality of filter bags; the method comprising: leading the drying air or gas from the source and the openings from below and up along sides of the plurality of filter bags; supplying the drying air or gas from the source of the drying air or gas to the one or more drying or gas supplies after wet cleaning of the plurality of filter bags and before the filter system enters the product-containing gas cleaning mode; and applying the drying air or gas to the plurality of filter bags so as to dry the plurality of filter bags.

10. A filter system, comprising: a filter housing comprising: an inlet for a product-containing gas, for the product-containing gas to be cleaned by filtering in a product-containing gas cleaning mode of the filter system; an outlet for cleaned gas; and a partition wall dividing the filter housing into a product chamber for the product-containing gas and a clean-gas chamber, wherein the partition wall is provided with a number of openings from which a plurality of filter bags extend downwards into the product chamber; wherein the inlet for the product-containing gas is placed in an upper part of the product chamber and in open communication with the product chamber, and configured for supplying the product-containing gas to the product chamber in the product-containing gas cleaning mode, wherein cleaning of the product-containing gas is accomplished by the product-containing gas flowing into insides of the plurality of filter bags and filtered gas from the plurality of filter bags flows upwards into the clean-gas chamber, from where the filtered gas is discharged through the outlet for clean gas; a source of a drying air or gas; one or more drying air or gas supplies having openings placed in an upper part of the product chamber and are configured for leading drying air or gas towards a lower part of the plurality of filter bags after a wet cleaning mode of the filter system, wherein during the wet cleaning mode and prior to the filter system entering the product-containing gas cleaning mode, the plurality of filter bags are wet cleaned; and wherein the drying air or gas is for drying the plurality of filter bags.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other features and advantages of the present invention will become readily apparent to those skilled in the art by the following detailed description of exemplary embodiments thereof with reference to the attached drawings, in which:

(2) FIG. 1 shows a cut through an embodiment of a filter system in accordance with the present invention, where a number of inlets or supplies for drying air or gas is placed at a lower part of the filter housing and shown with a product discharge outlet;

(3) FIG. 2 shows a section of the filter system of FIG. 1;

(4) FIG. 3 shows an inlet or supply for drying air or gas for the filter system of FIG. 1;

(5) FIG. 4 shows an outside view of the filter system of FIG. 1, but not showing the product discharge outlet;

(6) FIG. 5 shows a second embodiment of a filter system with an alternative supply of drying air or gas in accordance with the present invention;

(7) FIG. 6 shows a third embodiment of a filter system with an inlet or supply for drying air or gas placed in an upper part of the filter housing in accordance with the present invention;

(8) FIG. 7 shows a cut through of the filter system shown in FIG. 6;

(9) FIG. 8 shows a fourth embodiment of a filter system with an inlet or supply for drying air or gas placed in a lower part of the filter housing in accordance with the present invention;

(10) FIG. 9 shows a cut through of the filter system shown in FIG. 8;

(11) FIG. 10 shows a fifth embodiment of a filter system with an inlet or supply for drying air or gas passed through a clean-gas chamber of the filter system in accordance with the present invention;

(12) FIG. 11 shows a cut through of the filter system shown in FIG. 10;

(13) FIG. 12 shows a sixth embodiment of a filter system with an inlet or supply for drying air or gas passed through the clean-gas chamber of the filter system in accordance with the present invention;

(14) FIG. 13 shows a cut through of the filter system shown in FIG. 12; and

(15) FIG. 14 shows a section of the filter system with an inlet or supply for drying air or gas of FIG. 13.

DETAILED DESCRIPTION

(16) Various embodiments are described hereinafter with reference to the figures. Like reference numerals refer to like elements throughout. Like elements will, thus, not be described in detail with respect to the description of each figure.

(17) It should also be noted that the figures are only intended to facilitate the description of the embodiments.

(18) They are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an illustrated embodiment needs not have all the aspects or advantages shown.

(19) An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described.

(20) Throughout, the same reference numerals are used for identical or corresponding parts.

(21) According to the invention, a filter system 1 includes a filter housing 2 with an inlet part 3 and a clean-gas outlet 4. The filter system 1 further includes a partition wall 5 dividing the filter housing 2 into a product chamber 6 and a clean-gas chamber 7, the partition wall 5 being provided with a number of openings from which a plurality of filter elements 8 extends downwards into the product chamber 6, which inlet part 3 is placed in an upper part of the product chamber 6 and in open communication with the product chamber 6, and configured for supplying a product-containing flow of gas to the product chamber 6, the gas flow being conveyed through the filter elements 8 and upwards into the clean-gas chamber 7, from where the filtered gas is discharged through the clean-gas outlet 4.

(22) The partition wall 5 is most often an apertured plate or tube sheet, which divides the filter housing into a gas-cleaning chamber or product chamber 6 and a clean-gas take-off chamber or plenum 7. The partition wall 5 supports a plurality of tubular filter elements 8 within the product chamber 6, so when a product-containing gas is directed through the inlet 3 into the product chamber 6, the gas passes through the filter elements 8 and leave the filter housing 2 through the clean-gas chamber 7 and the clean-gas outlet 4. Particulate materials separated from the product-containing gases are deposited on the exterior of each filter element 8 and are afterwards lead out through a discharge outlet 13 at the bottom 9 of the filter housing 2, which is well known in the art. To accommodate cleaning of the filter elements 8, the filter housing 2 (or bag house in case bag filters are used) includes a reverse-flow flushing arrangement, pulse cleaning, a filter element shaking system or the like (not shown). Further, when the filter system 1 is stopped due to wet cleaning, the filter elements 8 are cleaned with liquid, which liquid is to be dried before the filter system 1 can enter operational mode again.

(23) The product discharge outlet 13 is connected to the bottom 9 of the filter housing 2 and the outlet 13 can be provided with a valve 17 in a valve housing 15, which valve 17 can rotate in the housing 15 around an axle 16 in order to open and close the valve 17. When the valve 17 is open, product from the filter housing can be removed and after wet cleaning of the filter elements 8, liquid can be removed through the valve. Between the discharge outlet and the filter housing, an air or gas inlet 14 for drying air or gas can be placed. The valve 17 in this embodiment is configured as a rotor shown in FIG. 1 with four wings or vanes, forming four cells within the housing 15. Hereby is obtained that the valve or rotor 17 can be turned for discharging product through the outlet 13 as a kind of airlock without opening for free passage of air through the lock. In other embodiments, the valve or rotor can be provided with six, eight or ten wings or vanes forming the same number of cells in the rotor 17. If drying air or gas is to be injected into the filter system 1 through the discharge outlet 13 in this embodiment, the valve or rotor 17 must be removed first. The valve or rotor 17 can have any number of wings or vanes, as long as it is able to function as an airlock.

(24) In an embodiment (not shown) two or more valves can be placed in series one above the other in the discharge outlet 13. Hereby it is possible to close the lower valve and open the upper valve. Then product powder will enter a space between the two valves. Now the upper valve can be closed and the lower valve opened, and product is thereby discharged from the filter. This sequence can be repeated discharging product from the filter housing without need for pausing the filtering process.

(25) The valves 17 can be butterfly valves, flap valves or similar valves. When more than one valve 17 are used, both or all valves are open, when injecting drying air or gas through the valves 17 in the product discharge opening 13.

(26) In an embodiment the drying air or gas inlet 14 and/or an air or gas inlet through the product discharge outlet 13, can be used as an additional drying air or gas supply.

(27) Here an additional drying air or gas inlet 14 and/or an air or gas inlet through a product discharge outlet 13 supplies an additional drying air or gas to the filter system 1.

(28) In an alternative embodiment, one or more drying air or gas supplies 10 are replaced by an additional drying air or gas supply 14 connected to a bottom 9 of the filter housing 2.

(29) In an alternative embodiment, one or more drying air or gas supplies 10 are replaced by an additional drying air or gas supply supplied through a product discharge outlet 13 connected to a bottom 9 of the filter housing 2.

(30) In these embodiments the drying air or gas inlet 14 and/or an air or gas inlet through the product discharge outlet 13, can be used as main supply of drying air or gas and even as the only drying air or gas supplies.

(31) Hereby the drying air or gas supply 14 and/or a drying air or gas supply through the product discharge outlet 13 replaces the drying air or gas supplies 10 connected to the filter inlet 3 or to the filter housing 2.

(32) This is illustrated in FIG. 1 showing also the air or gas supplies 10, but these embodiments can also be carried out without the drying air or gas supplies 10 as well as being added to the rest of the embodiments shown in the rest of the figures.

(33) It is clear that if drying air or gas is supplied through the product discharge outlet 13, the valve or valves 17 must be open.

(34) To be able to minimize the down time for the filter system 1 after wet cleaning, the filter system 1 is provided with one or more air or gas supplies 10 placed in the product chamber 6 below the inlet part 3 and configured for leading drying air or gas into or out of the filter system 1.

(35) Down time for the filter system 1 can be explained as the time from stopping the filter system 1 and until the filter elements 8 are dried. Only the drying time of the down time can be shortened by this invention.

(36) Drying air or gas should be understood as drying air or drying gas.

(37) In an embodiment, the one or more drying air or gas supplies 10 is placed in a lower part of the filter housing 2 and having openings 11 placed below the filter elements 8. Placing the one or more drying air or gas supplies 10 in a lower part of the filter housing 2 and the drying air or gas supplies 10 having openings 11 placed below the filter elements 8 ensures a flow of drying air or gas from below and up along sides of the filter elements 8, optimizing the drying process.

(38) In an embodiment, the one or more drying air or gas supplies 10 is placed in a lower part of the filter housing 2 and having openings 11 placed at a level corresponding to a lower part of the filter elements 8. Hereby is also ensured that drying air or gas is supplied along or along most of a length of the filter elements 8.

(39) In an alternative embodiment, the one or more drying air or gas supplies is connected to the bottom 9 of the filter housing 2 or to the discharge outlet for removing product.

(40) In an embodiment, the one or more drying air or gas supplies 10 is placed in an upper part of the filter housing 2 and having openings 11 directing drying air or gas towards the lower part of the filter elements 8. Hereby the drying air or gas is entered into the filter housing 2 in a direction different from a perpendicular direction in relation to the filter elements 8 giving a flow of drying air or gas within the filer being substantially in a lengthwise direction in relation to the filter elements 8 giving a circulation of drying air or gas from the upper part of the filter housing 2 in a downwards direction towards the lower part of the filter housing 2 along the filter elements 8.

(41) In an embodiment the air or gas supplies 10 directs the drying air or gas in a downwards angle towards the lower part of the filter elements 8.

(42) In an alternative embodiment, the drying air or gas is directed towards the filter elements 8 by use of baffles, guide elements or the like (not shown).

(43) In an embodiment the one or more drying air or gas supplies 10 is connected to the filter inlet 3 passing drying air or gas through the filter inlet 3 and through one or more drying air or gas supplies 10.

(44) In an embodiment, the drying air or gas can also be supplied through the clean-gas outlet tube 4 to pass drying air or gas into the filter system 1 in a reverse direction (not shown) compared to normal operation.

(45) In an alternative embodiment, the drying air or gas supplies 10 can be connected directly to the clean gas outlet tube 4.

(46) These embodiments provides for supply of drying air or gas in a flow from the upper part of the filter elements 8 and downwards along the filter elements 8.

(47) In an embodiment one or more drying air or gas supplies 10 is placed as a combination of one or more placements mentioned in one or more of the above embodiments, leaving a possibility for supplying and/or extracting or leading out drying air or gas from the filter housing 2 from different or several connection points.

(48) In an embodiment the one or more drying air or gas supplies 10 is connected to the filter inlet 3 and/or the clean-gas outlet 4 and/or discharge outlet for removing product (not shown), the one or more drying air or gas supplies 10 being closed by a closer or closing means 12 during normal operation and open during drying of the filter elements 8. Here it is possible to make use of existing piping in the filter system 1 the supply or extract drying air or gas from the filter housing 2. The closer or closing means 12 can be butterfly valves, flap valves or similar closer or closing means 12.

(49) In an embodiment, the drying air or gas is passed into the filter system 1 through the clean-gas chamber 7 and out of the filter system 1 through the one or more drying air or gas supplies 10. Hereby a reverse flow in the filter system is obtained as an option of supply of drying air or gas. This is a situation as opposed to normal operation of the filter system. Hereby the filter elements 8 are dried by blowing drying air or gas from inside the filter elements 8.

(50) In an alternative embodiment, drying air or gas can provided through the filter inlet 3 using the drying air or gas supplies 10 as outlets for the drying air or gas.

(51) To dry the filter elements 8 of a filter system 1 method is provided, where drying air or gas is supplied to the filter elements 8 after wet cleaning of the filter elements 8, by passing drying air or gas through the filter inlet 3 and/or through one or more drying air or gas supplies 10.

(52) In an embodiment of the method, drying air or gas is passed into the filter 1 through the filter inlet 3 and at least a part of the drying air or gas is directed out of the filter 1 through the one or more drying air or gas supplies 10.

(53) The person skilled in the art realizes that the present disclosure is not limited to the preferred embodiments described above. The person skilled in the art further realizes that modifications and variations are possible within the scope of the invention. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the disclosure, from a study of the drawings, and the disclosure.