Title of Invention

CLEANING DEVICE FOR BAG HOUSE FILTER

Abstract The present invention relates to a device for bag house filters for cleaning of gases containing solid particles said filter comprising at least two chambers 1 each Chambers containing a plurality of filter bags 2 and where a bottom hopper 3,53 is arranged below each chamber 1. The device comprises a distribution device 4,54 having an inlet opening 5,55 for uncleaned gas and separate opening 6,56 connected to each of the bottom hoppers 3,53, a Device 13,57 for closing of uncleaned gas to one at a time of the openings 6,56 in the distribution device 13,57 connected to each of the bottom hoppers 3,53 and : for simultaneously opening of an outlet opening 8 in the Distribution device, a fan 11 for cleaning of the filter ~ bags 2 in the chamber 1 which is closed for supply of uncleaned gas and or simultaneously transport by suction of particles via the outlet opening 8 in the distribution device 4,54 and to a silo 10 for collected particles.
Full Text Field of Invention
The present invention relates to a cleaning device for bag house filters used for removing solid particles from gases and more specifically a device for use in connection with the cleaning of the bags in such bag house filters and for the transport of particles removed from the gas.
Background art
The expression "bag house filters" shall be understood to mean filters where the gas to be cleaned for solid particles is passed through a filtering cloth. In such filters the filtering cloth is usually in the form of bags where uncleaned gas is passed through the filtering cloth, either by supplying uncleaned gas into the bags and passing the gas through the filter cloth whereby solid particles are retained on the inside of the filter cloth, or by passing uncleaned gas through the filtering cloth from the outside, whereby the solid particles are retained on the outside of the filter bag. The following description will be concerned with bag house filters of the kind where uncleaned gas is supplied into the bags, but the invention is also applicable to other kinds of bag house filters.
Bag house filters are each made up of a plurality of chambers, each chamber containing a plurality of normally, vertically arranged filter bags. Uncleaned gas is supplied into the bags and the gas is passed through the material in the bags, while the solid particles are retained on the inside of the bags. After having been in

operation for a certain period of time, the bags have to be cleaned for solid particles. This is done by disconnecting the supply of uncleaned gas to the chamber to be cleaned whereafter the bag in the disconnected chamber is cleaned by supplying cleaning gas in the opposite direction to the direction of the uncleaned gas. This can be done in a number of ways. By the so-called "pulse-jet", a short and strong pressure pulse is supplied from the clean gas side of the filter bags whereby the solid particles which are retained on the bags will be removed. By the so-called "reverse-air" system, the cleaning gas is also supplied in the opposite direction of the uncleaned gas. The basic difference between "pulse-jet" and "reverse air" is that "reverse air" is based on cleaning using a low pressure difference for a longer period of time in contrast to the short and strong pressure pulse used by "pulse-jet". It is further known to remove retained particles from the filter bags by the use of sound vibration and by mechanical vibration of the bags. Finally, combinations of the above mentioned cleaning methods can be used.
The particles contained in the chamber which is cleaned will fall down into a closed bottom hopper situated below the chamber and are thereafter transported through valves or the like to a storage silo by means of pneumatic transport or by means of other ways of transporting such as chain conveyer or other ways of mechanical transport.
The known methods for cleaning of the filter bags and for transporting the collected particles from the bottom hoppers to the silo have a number of drawbacks. Firstly, all the known systems are based on the use of separate systems for cleaning of the filter bags and for transport

of the particles from the bottom hoppers to the silo. In order to clean the filter bags in the chamber, each chamber has to be equipped with separate flap valves for opening and closing the cleaning gas supply to the chamber. Furthermore, the cleaning gas will, after having passed through the bags in the chamber which are being cleaned, contain a substantial amount of particles and must itself therefore be returned to the filter for cleaning. This represents an additional load on the filter. Further, each of the bottom hoppers must be equipped with means for discharging particles from the hoppers. The means for discharging of particles from the bottom hoppers is complicated and needs a lot of maintenance in order to avoid leakages of particles to the surroundings. Finally, separate regulating and control systems for the cleaning of filter bags and for transport of particles from the bottom hoppers are needed, which increases the complexity of the filters.
Disclosure of the Invention
It is an object of the present invention to provide a device for bag house filters for cleaning of gases containing solid particles whereby the cleaning of the filter bags and the transport of the collected particles are combined. This represents a substantial simplification of the design of the filters and of the controlling and regulating systems of the bag house filter.
Accordingly, the present invention relates to a cleaning device for a bag house filter system, the filter system being arranged to remove solid particles from a flow of gas, the filter system comprising at least two chambers each chamber containing a plurality of filter bags and a

bottom hopper arranged below each chamber, and in which the cleaning device comprises a distribution device, a fan and a silo for collected particles; the distribution device having an inlet opening for uncleaned gas, separate openings connected to each of the bottom hoppers, and a diverter for selectively closing the supply of uncleaned gas to one at a time of the openings in the distribution device while simultaneously opening an outlet opening in the distribution device to the respective opening; the fan being operatively connected to the outlet opening and so to the chamber which is closed for supply of uncleaned gas whereby gas is drawn in the reverse direction through the chamber which is closed for the supply of uncleaned gas, and particles are removed and simultaneously transported by suction via the outlet opening in the distribution device and to the silo.
According to a preferred embodiment the distribution device comprises a chamber having a circular cross-section. The lower part of the distribution device is preferably of conical shape with the openings connected to each of the bottom hoppers arranged about the periphery of the conical part of the distribution device. The outlet opening is preferably arranged in the bottom of the distribution device.
The fan is preferably arranged after a silo filter, cyclone or the like, but can also be placed between the outlet opening of the distribution device and the silo filter.
The diverter or device for closing the supply of uncleaned gas to one of the openings in the distribution

device connected to the bottom hoppers, preferably comprises a sheet arranged inside the distribution device which sheet is rotatably arranged on a vertical axle which extends down below the bottom of the distribution device. The sheet preferably has such a shape and size that it closes the supply of uncleaned gas to one of the chambers at the same time as it forms an open channel from the bottom hopper of this chamber through the outlet opening in the distribution device. The axle to which the sheet is connected can be rotated by means of a motor or the like. The sheet can thereby by rotation of the axle be moved from one opening to the next opening in the sidewall of the distribution device whereby one chamber at a time is closed for supply of uncleaned gas at the same time as the chamber which is closed for supply of uncleaned gas is opened towards the outlet opening of the distribution device. The chamber which is closed for supply of uncleaned gas will thus be cleaned for particles retained on the filter bag as the fan will suck clean gas through the bags whereby retained particles will fall downwardly into the bottom hopper below the chamber whereafter the particles are transported through the outlet opening of the distribution device and to the silo for storage of the particles.
Thus, by the present invention both the cleaning of the filter bags and the transport of retained particles are controlled by rotation of the device for closing one at a time of the openings in the distribution device for supply of uncleaned gas. Naturally, the construction could be arranged to close more than one chamber at a time, if preferred.
According to another embodiment of the present invention.

the chambers of the bag house filter are in the form of adjacently arranged segments with the distribution device arranged in the centre of the bag house filter and each of the bottom hoppers is directly connected to the openings in the distribution device in order to supply uncleaned gas to the chambers. This arrangement gives a very compact filter which does not require much space and which will be easy to maintain. Further, the filter can be divided into a large number of chambers which results in less additional load on the remaining chambers when one of the chambers is being cleaned.
By means of the present invention, recirculation of collected particles during cleaning of the filter bags is avoided. In this way the load on the filter is reduced. Further, the bottom hoppers can be smaller than conventional hoppers due to the fact that the transport of the collected particles from the bottom hoppers is carried out with a relatively high amount of gas.
By means of the present invention, a substantial simplification of the design of the filter can be achieved as separate valves for supply of cleaning gas to each chamber are not needed. Further, transportation devices from each of the bottom hoppers are not needed a they are replaced by simple pipe connections for connecting the outlet opening in the bottom hoppers with the distribution device.
The device according to the present invention can be implemented on existing bag house filters by incorporating the distribution device and by connecting the outlet openings of the bottom hoppers in each chamber to the distribution device.

The invention may be carried into practice in various ways and some embodiments will now be described by way of example, with reference to the accompanying drawings.
Brief description of the drawings
Figure 1 shows a bag house filter according to the invention, as seen from above;
Figure 2 shows a vertical section through the filter along line I-I in Figure 1;
Figure 3 shows a filter according to the invention incorporated into a conventional filter, as seen from above; and
Figure 4 shows a vertical section along line II-II in Figure 3.
Detailed description of the Invention
Figures 1 and 2 show a bag house filter comprising a plurality of chambers 1 where each chamber contains a plurality of filter bags 2. The filter chambers 1 are of conventional design. Each of the chambers comprises bottom hopper 3, which preferably has a conical form.
Between the chambers 1 there is arranged a distribution device 4 for distribution of uncleaned gas to the chambers 1 and for transport of the collected particles. At least the lower part of the distribution device 4 is of conical design. The distribution device 4 has an inlet opening 5 at its upper end for the supply of uncleaned gas. In the lower conical part of the distribution device 4 there are openings G which via

pipes 7 are connected to the bottom hoppers 3 in the chambers 1. The distribution device 4 has at its lower end an outlet opening 8 which is connected via a pipe 9 to a silo 10 for storage of the particles removed from the gas. A fan 11 is operatively connected to the pipe 9 and upstream of the fan 11 there is a silo filter 12.
In the distribution device 4 there is also a rotatable closing and opening device 13 for closing the openings 6 one at a time in order to supply uncleaned gas to the chambers 1. The device 13 comprises a sheet 14 which closes the opening 6. The sheet 14 is arranged to be rotated about an axle 15 by means of a motor 16. The sheet 14 is of such a design that when the device 13 is brought to a position where the sheet 14 closes a particular one of the outlet openings 6, this outlet opening 6 will communicate with the outlet opening 8 in the bottom of the distribution device 4. At the same time, the device 13 is so designed that when it is in this position, the inlet opening 5 of the distribution device 4 communicate with all of the openings 6 except the particular one. Uncleaned gas will thereby be supplied to all of the chambers 1 except this one. Uncleaned gas will thereby flow to the chambers 1 and through the filter bags 2. Solid particles contained in the gas will be retained on the inside of the filter bags.
When one of the chambers 1 is to be cleaned for retained particles, the device 13 is rotated to a position where the sheet 14 closes the opening of the chamber 1 to be cleaned. The fan 11 in the pipe 9 which connects the outlet opening 8 in the bottom of the distribution device with the silo 10, will thereby create a reduced pressure

in the chamber 1 which is closed for the supply of uncleaned gas. This reduced pressure will cause particles retained on the walls of the filter bags to fall down into the bottom hopper 3 and the particles will immediately be transported to the silo. When the cleaning of the filter bags and the transport of particles are complete, the device 13 is rotated to such a position that uncleaned gas is again supplied to the chamber 1 which has been cleaned, while the opening 6 for the next chamber 1 is closed for uncleaned gas and is opened for cleaning of the filter bags and the transportation of particles. This sequence is repeated at preset intervals.
Figures 3 and 4 show a second embodiment of the present invention.
Figures 3 and 4 show a bag house filter having a rectangular shape. The filter is divided into a plurality of chambers 50. Below the chambers 50 there is a funnel shaped hopper 51 which, by means of inner partition walls 52, is divided into one bottom hopper 53 for each chamber 50. Centrally located in the bottom of the funnel shaped hopper 51 there is a distribution device 54 of the same kind as described above in connection with Figures 1 and 2. The distribution device 54 has a gas inlet opening 55 for uncleaned gas in its upper part and in its lower conical part the distribution device 54 is equipped with openings 56 which each communicate directly with one of the bottom hoppers 53. Inside the distribution device 54 there is a rotatable closing and opening device 57 for successively closing and opening of one of the openings 56 for the supply of uncleaned gas to the chambers 1. The device 57 is of the

same kind as the device 13 described above in connection with the embodiment shown in Figures 1 and 2. The distribution device 54 operates in the same way as described in connection with Figures 1 and 2.


WE CLAIM:
1. A cleaning device for a bag house filter system, the filter system being arranged to remove solid particles from a flow of gas, the filter system comprising at least two chambers each chamber containing a plurality of filter bags and a bottom hopper arranged below each chamber, and in which the cleaning device comprises a distribution device, a fan and a silo for collected particles; the distribution device having an inlet opening for uncleaned gas, separate openings connected to each of the bottom hoppers, and a diverter for selectively closing the supply of uncleaned gas to one at a time of the openings in the distribution device while simultaneously opening an outlet opening in the distribution device to the respective opening; the fan being operatively connected to the outlet opening and so to the chamber which is closed for supply of uncleaned gas whereby gas is drawn in the reverse direction through the chamber which is closed for the supply of uncleaned gas, and particles are removed and simultaneously transported by suction through the outlet opening in the distribution device and to the silo.
2. The device as claimed in claim 1, in which the distribution device comprises a chamber having a circular cross-section.
3. The device as claimed in claim 2, in which the lower part of the distribution device is of conical shape with the openings connected to each of the bottom hoppers arranged about the periphery of the conical part of the distribution device.
4. The device as claimed in claim 1, in which the diverter for selectively closing the supply of uncleaned gas to one of the openings in the distribution device connected to the bottom hoppers, comprises a sheet arranged inside the distribution device which

sheet is rotatably arranged on a vertical axle which extends down below the bottom of the distribution device, the sheet having such a shape and size that is closes the supply of uncleaned gas to one of the chambers at the same time as it forms an open channel from the bottom hopper of this chamber through the outlet opening in the distribution device.

Documents:

0887-mas-1997 abstract duplicate.pdf

0887-mas-1997 abstract.pdf

0887-mas-1997 claims.pdf

0887-mas-1997 cliams duplicate.pdf

0887-mas-1997 correspondece-others.pdf

0887-mas-1997 correspondece-po.pdf

0887-mas-1997 description (complete) duplicate.pdf

0887-mas-1997 description (complete).pdf

0887-mas-1997 drawings.pdf

0887-mas-1997 form-19.pdf

0887-mas-1997 form-2.pdf

0887-mas-1997 form-4.pdf

0887-mas-1997 form-6.pdf

0887-mas-1997 others.pdf

0887-mas-1997 pct search report.pdf

0887-mas-1997 petition.pdf

0887-mas-1997form-26.pdf


Patent Number 202260
Indian Patent Application Number 887/MAS/1997
PG Journal Number 05/2007
Publication Date 02-Feb-2007
Grant Date 14-Sep-2006
Date of Filing 28-Apr-1997
Name of Patentee M/S. ELKEM ASA
Applicant Address HOFFSVEIEN 65B, 0377, OSLO,
Inventors:
# Inventor's Name Inventor's Address
1 ANDERS SORHUUS KLAEBUVEIEN 34, 7030 TRONDHEIM,
PCT International Classification Number B01D 46/04
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 961735 1996-04-29 Norway