WO1982002675A1

WO1982002675A1 - Method and device for freeing a trap filter of dust

Info

Publication number: WO1982002675A1
Application number: PCT/SE1982/000034
Authority: WO
Inventors: Ab Patronax
Original assignee: Nilsson Dan
Priority date: 1981-02-10
Filing date: 1982-02-08
Publication date: 1982-08-19
Also published as: JPS58500109A; SE426915B; SE8100923L; AU8008582A; GB2118456A; DE3233705T1; GB2118456B

Abstract

Method and device for freeing a filter medium, which has a certain inherent stiffness and is comprised in a filter, of dust separated from air, which filter (2) at one end is connected to a supporting plane (1) and in its longitudinal direction is oriented substantially perpendicularly to the supporting plane (1). The cleaning of the filter cloth is effected in that a strocke is imparted to the supporting plane (1), whereby a shock wave is created which propagates downward along the filters. This results in that the filters are subjected to vibration in their longitudinal direction whereby the dust adhering to the filter medium loosens and drops down.

Description

Method and device for freeing a trap filter of dust

This invention relates to a method and a device for freeing a filter medium with a certain inherent stiffness comprised in a filter of dust separated from air, which filter is connected with one end to a supporting plane and in its longitudinal direction oriented substantially perpendicularly to the supporting plane.

Several different methods are previously known, according to which filters are freed of dust or particles.

Tubular filters often are cleaned by compressed air, which is pressed in a direction opposed to the air flow direction. The equipment for carrying out such cleaning, however, is relatively expensive.

For cleaning so-called cassette filters usually a vacuum cleaner of a special type is employed which by sucking action removes the dust adhered in the filter.

At the two aforementioned methods the operation must be interrupted for being able to carry out the cleaning.

In so-called textile trap filters the filter elements often are designed as hoses suspended on an upper horizontal frame, which in its turn is resiliently suspended. When cleaning such filters, a stroke in horizontal direction is imparted to the frame, which stroke propagates in an oscillating movement downward along the filter elements. This oscillating movement, however, is quenched relatively rapidly, and the cleaning, therefore, will be non-uniform along the height of the filter elements.

The present invention has the object to provide a method and a device for cleaning a filter medium, at which the cleaning can be carried out with operation in progress and with relatively inexpensive equipment. in addition, a uniform cleaning along the entire height of the filter medium is obtained. This object of the invention is realized in that the method and the device have been given the characterizing features defined in the attached claims.

An embodiment of the invention is described below with reference to the accompanying drawings, in which Fig. 1 is a section along I-I in Fig. 2,

Fig. 2 is a horizontal view of the device according to the invention, and Figs. 3a-3c are schematic views of a cleaning sequence.

The air filtering device shown in Figs. 1 and 2 comprises a supporting plane 1, which includes a number of holes, in which a number of so-called filtering tubes 2 are located. The edges of the supporting plane 1 rest on a frame (not shown). The filtering tubes 2 are supported relative to the supporting plane 1 by a supporting collar attached to the upper edge of the tubes 2.

A funnel-shaped casing 3 connected to the supporting plane 1 extends below the supporting plane 1 and encloses the filtering tubes 2. The funnel-shaped casing 3, thus, tapers downward and terminates with an opening 4, through which particles removed from the filtering tubes 2 drop out.

The funnel-shaped casing 3 also includes a supply air chamber 5 with an inlet opening 5a. The supply air flows through the chamber 5 before is passes through the filtering tubes 2.

In order to secure that the dust-laden supply air is guided beneath the lower ends of the filtering tubes, a partition wall 6 is attached to that side of the chamber 5 which faces to the filtering tubes.2. The partition wall 6 extends a distance beneath the lower ends of the filtering tubes 2 and its lower edge is bent to the centre of the casing 3.

Above the supporting plane 1 a spent air chamber 7 with an outlet opening 7a is located.

In connection to the supporting plane 1 an impact mechanism 8 is located, which comprises two rockingly mounted rods 9, one ends 9a of which extend inward to the central line of the supporting plane, and the other ends 9b of which extendslightly outside the supporting plane 1. The mounting point 10 for the rods 9 is located immediately outside the edge of the supporting plane 1. At the inward facing ends 9a of the rods 9 striking heads 11 are attached, which in non-operative position abut plates 12 positioned in the supporting plane 1.

On the supporting plane 1 two plates 12 are attached, which receive the strokes from the heads 11 when the impact mechanism 8 is actuated. If the supporting plane 1 would not include plates 12, the plane would be deformed when being hit by the striking head 11.

The impact mechanism 8 also comprises actuating members in the form of two cam disks 13, which are mounted eccentrically on a rotary shaft 14 driven by a power source, for example an electric motor 15.

The device described above operates in the manner as follows.

The dust-laden supply air is fed into the chamber 5 whereafter it is guided downward to the lower side of the filtering tubes

2. From there the air flows from the outside through the walls of the filtering tubes 2 and thereafter upward into the spent air chamber 7, from which it is removed through the outlet opening 7a.

The walls of the filtering tubes 2 may consist of a folded paper-like filter cloth, the folds of which usually run in axial direction relative to the tubes.

When the dust-laden air passes through the walls of the filtering tubes 2, the greater part of the separated dust adheres to the outside of the walls of the filtering tubes 2. This dust gradually will clog the filter cloth, whereby the air amount allowed per time unit to pass through the filtering tubes 2 is reduced substantially. In order to remedy this inconvenience, the filter clothes must be cleaned regularly. In the following is described how a cleaning sequence proceeds, with reference being made to Figs. 3a-3c.

By studying the configuration of the cam disk 13 in Fig. 1, it is understood that upon rotation of the disk in the direction of the arrow the outer end 9b of the rod 9 first is moved downward whereby the opposed end 9a and the striking head 11 are lifted. When the cam disk 13 has been rotated through such a distance that its "notch" is located directly in front of the end 9b, this end moves upward, and the opposed end 9a with the striking head 11 move downward. The downward movement of the striking head 11 is braked when the head meets the plate 12, whereby a downward directed accel- eration is imparted to the supporting plane. At continuous rotation of the cam disk 13 said movement of the rod 9 with the striking head 11 will be repeated.

In Fig. 3a the striking head 11 is shown in non-operative position, in which it abuts the plate 12. Thereafter the striking head 11 is lifted in the way described above, see Fig. 3b, whereafter it drops down and meets the plate 12, see Fig. 3c. The supporting plane 1 thereby is caused to accelerate downward in the region of the plate 12, which implies that the supporting plane 1 is imparted with a downward deflection according to Fig. 3c.

When the striking head 11 meets the plate 12, a shock wave is produced which propagates downward through the filtering tubes 2. The filtering tubes 2 thereby are caused to vibrate in axial direction, whereby the dust adhered to the filter cloth of the tubes 2 loosens from the filter cloth and is discharged through the opening 4.

Owing to the fact that the acceleration proceeds in axial direction of the filtering tubes 2, and the filter cloth is mounted on a central tube, for example of expanded metal, the shock wave propagates along the entire length of the filtering tubes without being damped appreciably. This implies that the entire filter cloth is subjected to vibration. The dust adhered on the filter cloth thereby loosens and by gravity drops down along the filter clothes. As the filtering tubes do not have any lower end disc, the dust continues to fall and drops out through the opening 4.

The device according to the invention, thus, renders possible efficient cleaning of the filtering tubes 2 without interrupt ing the operation.

It is not necessary to design the filter tubular, nor must the filter medium consist of a folded filter cloth. It is also imaginable to apply the method according to the invention to a filter medium of, for example, ceramic material.

The invention may also in other respects be varied within the scope of the attached claims.

Claims

1. A method of freeing a filter medium, which has a certain inherent stiffness and is comprised in a filter, of dust separ- ated from air, which filter (2) with one end is connected to a supporting plane (1) and in its longitudinal direction is oriented substantially perpendicularly to the supporting plane CD, c h a r a c t e r i z e d i n that to the filter (2) a vibration movement of short duration is imparted in the longitudinal direction of the filter.

2. A method as defined in claim 1, c h a r a c t e r i z e d i n that the vibration movement is effected in that a shock wave propagates in the longitudinal direction of the filter (2).

3. A method as defined in claim 3, c h a r a c t e r i z e i n that the shock wave is produced in that the supporting plane (1) is subjected to a stroke.

4. A device for cleaning a filter medium, which has a certain inherent stiffness and is comprised in a filter, of dust separated from air, which filter (2) with one end is connected to a supporting plane (1) and in its longitudinal direction is oriented substantially perpendicularly to the supporting plane (1), c h a r a c t e r i z e d i n that it comprises an impact mechanism (8)located in connection to the supporting plane (1), and members (13,14,15) for at certain intervals to actuate the impact mechanism (8) so as to impart a stroke to the supporting plane (1).

5. A device as defined in claim 4, c h a r a c t e r i z e d i n that the impact mechanism (8). comprises at least one rocking rod (9), one end of which (9a) extends inward over the supporting plane (1) and carries a striking head (11), and the other end (9b) of which is located in connection to the actuating members (13,14,15).

6. A device as defined in claim 5, c h a r a c t e r i z e d i n that in the meeting point of the striking head (11) on the supporting plane (1) a plate (12) is located.

7. A device as defined in claim 5 or 6, c h a r a c t e r i z e d i n that the actuating members comprise a cam disk (13) associated with each rod (9), which disk is located on a shaft (14), which is rotated by a power source (15), for example an electric motor, and the cam disk (13) co-operates with that end of the rod (9) which is remote from the striking head (11).