GB2321690A

GB2321690A - Valve cleaning

Info

Publication number: GB2321690A
Application number: GB9801279A
Authority: GB
Inventors: Walter Maag
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-01-22
Filing date: 1998-01-21
Publication date: 1998-08-05
Anticipated expiration: 2018-01-21
Also published as: GB9701295D0; GB2321690B; GB9801279D0

Abstract

A valve for use in paper or sewage industries comprises a housing having an inlet (3) and an outlet (4) adapted to be fitted in a pipeline. A valve member in the form of a valve plate (11) is movably mounted in a casing (1) between fully open and fully closed positions to control flow of fluid between the inlet and the outlet. The valve has means for cleaning the valve member in situ in the housing. The cleaning means comprises scraper blades (15) engageable with the sides of the valve plate (11) in a resilient manner and a pump for delivering cleaning fluid such as clean water or air to the casing (1) at a pressure higher than the pressure of fluid passing from inlet (3) to outlet (4). The cleaning fluid issues from the casing (1) in the form of a spray (34) between the scraper blades (15) and the valve plate (11) to clean the scraper blades and valve plate. The scraper blades can be replaced without dismantling the valve.

Description

Title: IMPROVEMENTS IN VALVES This invention relates to valves and is particularly, but not exclusively, concerned with valves for use in the paper making industry and in sewage treatment works.

A problem encountered in the paper making industry is the excessive wear which takes place on valve bodies and blades caused by foreign matter such as grit, staples and other sharp objects present in waste paper which is to be pulped prior to re-cycling. A similar problem occurs with solids waste products in sewage treatment works, coal mining, food preparation and many other industries.

With the conventional valves used, in particular in the paper industry, when the valve becomes so worn that it is no longer effective, it is necessary to stop production and remove the valve from the system in order that the valve can be stripped down and the worn valve re-conditioned or replaced. This is timeconsuming and wasteful of production time.

A further problem with conventional valves is that foreign objects can enter the valve body causing the valve to jam and thereby render it inoperative.

The present invention seeks to solve the above-mentioned problems by providing a valve having a self-cleaning facility and which can be readily serviced without the necessity to remove the entire valve assembly, including the casing, from a system in which the valve has been installed.

According to the invention, there is provided a valve comprising a housing having an inlet and an outlet adapted to be fitted in a pipe line, a valve member movably mounted in the housing between a fully open and a fully closed position and vice versa and arranged to control fluid flow through the housing between the inlet and the outlet, and means for cleaning the valve member while said valve member remains in situ in the housing.

The valve member cleaning means may comprise a pump arranged to supply a flow of cleaning fluid to the valve member in the housing, means for maintaining the cleaning fluid in the housing at a pressure above the pressure of fluid flowing through the housing from said inlet to said outlet and means for controlling the flow of cleaning fluid over the valve member to a passage in the housing leading from the inlet to the outlet which the valve member is arranged to control. The cleaning fluid is preferably clean water and the means for maintaining a pressure in the housing preferably takes the form of a non-return valve.

According to a preferred embodiment of the invention, the valve member takes the form of a substantially rectangular plate which is slidably movable in the housing. In the closed or partially closed position of the valve, the valve plate is arranged to extend into the passage in the housing between the inlet and the outlet.

Scraper blades are desirably provided on both sides of the valve plate to engage said plate and to scrape off any solid objects on that part of the valve plate extending into the passage when the valve plate is retracted or partially retracted from the passage. The scraper blades are preferably so arranged as to be readily replaceable without dismantling the valve.

The scraper blades may be made of a resilient material, such as rubber, or may be made of a rigid material and urged into engagement with the valve plate by resilient means such as a spring.

Grooves may be provided in the edges of the valve plate to facilitate the flow of cleaning fluid such as water through the housing. Guide means are desirably also provided for guiding movement of the valve member between the open and closed positions of the valve and vice versa.

The valve member may be actuated by pneumatic or hydraulic means or by other suitable means such as an electric stepping motor.

The invention will now be further described, by way of example, with reference to the drawings, in which: Fig. 1 is a longitudinal section through one embodiment of a valve according to the invention; Fig. 2 is a section of the valve shown in Fig. 1 on the line II-II in the direction of the arrows; Fig. 3 is a transverse section taken on the line III-III in Fig. 2; Fig. 4 is a transverse section taken on the line IV-IV in Fig. 2; Fig. 5 is a longitudinal section through a second embodiment of a valve according to the invention; and Fig. 6 is a section of the valve shown in Fig. 5 on the line V-V in the direction of the arrows.

In the drawings, like parts are denoted by like reference numerals.

Reference will first be made to Figs. 1-4 of the drawings in which the valve comprises a housing consisting of a substantially rectangular casing 1 to which a cylindrical member 2 is secured at one end. An inlet 3 is fitted to one end of the cylindrical member 2 and an outlet 4 is fitted to the other end of the cylindrical member 2, the inlet 3 leading to a passage or bore 5 in the cylindrical member from which the outlet 4 leads. Both the inlet and the outlet are provided with flanges 6 and 7 which are adapted to be fitted to suitable flanged pipe lengths in a pipe line (not shown).

The casing defines a cavity 9 in which a valve member in the form of a substantially rectangular plate 11 is installed. The valve plate 11 is fitted at one end with a piston rod 12 which extends out of the other end of the casing 1 through an end plate 13 which is detachably secured to the casing 1 by screws or bolts (not shown). A seal 14 is provided in an aperture in the end plate through which the piston rod 12 extends. The piston rod desirably terminates in a piston (not shown) located in a cylinder (likewise not shown) of a pneumatic or hydraulic ram for controlling operation of the valve member within the housing. In the fully open position of the valve, the valve plate 11 is retracted by the ram into the cavity 9 so that the bore 5 is clear to permit unimpeded flow through the valve.

In the closed position of the valve, the valve plate 11 is advanced by the ram into a position in which it extends from the cavity 9 across the bore 5 and butts against a seal 8 provided on the wall of the bore 5 to close the valve. Fig. 1 shows an intermediate position of the valve plate 11 in which it extends only partially into the bore 5 so that the valve is partially open.

If the valve according to the invention is installed in a plant for paper pulping in particular recycled paper or in a sewage works, foreign bodies such as sand or dirt or, in the case of recycled paper, staples can impinge on that part of the valve plate 11 which extends into the bore 5. In existing valves, these foreign bodies can cause excessive wear but this is avoided in the valve according to the invention by providing scraper blades 15 at the end of the cavity 9 which is adjacent to the bore 5. The scraper blades preferably consist of a resilient rubber material and are engaged with the sides of the valve plate 11 so that, as said plate is retracted into the cavity 9, any foreign bodies on the plate are scraped off by the scraper blades 15. The scraper blades 15 are mounted in respective guide plates 16 which are mounted in a replaceable manner in large grooves in the casing 1 so that they can be replaced when worn without the necessity of dismantling the valve. The guide plates 16 are located in position in the grooves in the casing 1 by guide covers 17.

As shown in Fig. 3, the ends of each groove in the casing 1 are closed by respective seal end stoppers 18 which are secured by screws 19 to a respective guide cover 17. A screw-threaded sleeve 21 extends from the centre of each guide cover 17 into the housing. A screw 22 provided at one end with a brass insert 23 is engaged with the screw thread of the sleeve 21 so that the brass insert 23 engages a respective edge of the valve plate 11 to guide the movement of the valve plate in the casing. A lock nut 24 is provided to immobilise the screw 22 once it has been adjusted to the position in which the brass insert 23 just makes contact with the edge of the valve plate 11. Each guide cover 17 is secured to the casing 1 by screws or bolts 25.

Movement of the valve plate 11 in the cavity 9 is also guided by guide plates 26 which are inserted at the rear of the valve and continue from the rear to the forward position of the scraper blades 15. These plates guide the blade 11 in a longitudinal manner. They are easily inserted and replaced from the rear of the casing simply by removing the end plate 13. A pair of screw-threaded sleeves 27 are provided in the side walls of the casing and a respective screw 28 provided at one end with a brass insert 29 is engaged with the screw-thread in each of the sleeves 27 and is so positioned that the brass insert 29 just makes contact with a respective edge of the valve plate 11. Lock nuts 31 are provided to secure the screws in this position.

A first conduit 32 is provided in the casing 1 which leads into the cavity 9 and a second conduit 33 is provided in the casing which leads from the cavity 9. The conduit 32 is connected to a pressurised water line or air line (not shown) which is arranged to deliver a cleaning fluid or pressurised air to the cavity 9 at a pressure at least 0.5 Bar above the pressure of fluid flowing through the bore 5.

As shown in the drawings, the cavity 9 is completely filled with clean or clarified water or air and flows out of the cavity 9 passing between the scraper blades 15 and the sides of the valve plate 11 to issue into the bore 5 in the form of a spray as indicated at 34 in Fig. 1 of the drawings. This flow of clean or clarified water or air will thus tend to have a self-cleaning action on the scraper blades 15 and the valve plate 11 when the valve blade is moved in an opening or closing direction. Pressure is maintained in the cavity 9 by a non-return valve (not shown).

Flow of water or air through the cavity 9 and cleaning of the valve plate 11 is enhanced if the edges of the valve plate 11 are provided with grooves or cutouts 35 as shown in Figs. 3 and 4 of the drawings.

When the valve plate 11 is moved in the cavity 9, the water pressure caused by water replacement can reach above 3 Bar pressure. During movement of the valve plate 11 in the opening or closing direction, the displaced water passes between the valve plate 11 and the scraper blades 15 to issue into the bore 5.

Should it be necessary to remove the valve plate 11 for maintenance or servicing or, simply, to retract the valve plate for replacement of worn strips 26, the guide covers 17 can be removed and the guide plates 16 holding the scraper blades 15 can be withdrawn and replaced by a blanking plate (not shown) to isolate the cavity 9 from the bore 5 so that fluid flow through the bore can continue unimpeded after the guide covers 17 have been re-fitted. It is therefore not necessary to shut down the plant while the valve is being serviced, maintained or repaired. The scraper blades 15 can be replaced, if necessary because of wear, while the guide plates have been withdrawn from the casing.

The valve plate 11 is preferably made of stainless steel and the casing is desirably made of plastics material such as cast nylon 6 or acetal although other materials may be utilised if desired. The scraper blades 15 are desirably made of a resilient material having the resilience of natural rubber but this is not essential and other materials such as plastics or stainless steel may be used if desired. The seal 8 in the bore 5 is preferably made of stainless steel but could be made of a resilient material such as rubber or plastics.

The embodiment shown in Figs. 5 and 6 of the drawings differs from the previous embodiment in that the scraper blades 15 are replaced by doctor blades 35 which are made of "Kirflex" or of a similar material which are mounted in respective bars 36 which are substantially circular in cross-section and are preferably made of bronze or stainless steel. The blades 35 are held tight against the sides of the valve plate 11 by a pair of tensioned coil springs 37 (only one shown) each of which is located at a respective side of the valve plate 11, each spring acting on the upper and lower blades 35 via levers 38 which engage with the respective bars 36. The bars 36 and blades 35 are mounted in a replaceable cartridge 39 which can easily be removed for maintenance and re-installed from either side of the casing 1, the cartridge being held in place by guide covers 17 as in the previous embodiment.

This embodiment is otherwise similar to the embodiment shown in Figs. 1-4 except that the casing 1 is also provided with a drain plug 41 which, when opened, enables an operator to wash the casing through as a precautionary measure to remove any residue or foreign bodies from the interior of the casing.

Such a drain plug may also be fitted to the embodiment shown in Figs. 1-4 of the drawings.

It will be seen that the valve according to the invention provides a considerable improvement over existing valves. Its self-cleaning action will prolong the life of the valve member by up to three times and, by means of the blanking plate, routine maintenance and/or emergency repairs can be carried out without having to dismantle the valve or remove it from the pipe line. Further, the self-cleaning facility and, in particular, the flow of clean or clarified water or air through the valve cavity at a pressure above that flowing through the bore 5 will prevent any foreign bodies from entering the valve body so that reliable operation of the valve according to the invention is ensured.

The invention is not restricted to the above-described embodiments but modifications and variations may be made without departing from the scope of the invention. For example, instead of being operated by a pneumatic or hydraulic ram, the piston rod could be operated by other means such as an electric stepping motor or hand wheel. Further, the valve according to the invention is not restricted to use in the paper industry but is also capable of being used in many other industrial applications.

Claims

1. A valve comprising a housing having an inlet and an outlet adapted to be fitted in a pipeline, a valve member movably mounted in the housing between a fully open and a fully closed position and vice versa and arranged to control fluid flow through the housing between the inlet and the outlet, and means for cleaning the valve member while said valve member remains in situ in the housing.

2. A valve according to claim 1, wherein the valve cleaning means comprise a pump arranged to supply a flow of cleaning fluid to the valve member in the housing, means for maintaining the cleaning fluid in the housing at a pressure above the pressure of fluid flowing through the housing from said inlet to said outlet and means for controlling the flow of cleaning fluid over the valve member to a passage in the housing leading from the inlet to the outlet which the valve member is arranged to control.

3. A valve according to claim 2, wherein the cleaning fluid is clean water.

4. A valve according to claim 2 or claim 3, wherein the means for maintaining pressure in the housing comprise a non-return valve.

5. A valve according to any one of claims 2 to 4, wherein the valve member takes the form of a substantially rectangular plate which is slidably movable in the housing and which, in the closed or partially closed position of the valve, is arranged to extend into the passage in the housing between the inlet and the outlet.

6. A valve according to claim 5, wherein scraper blades are provided on both sides of the valve plate to engage said plate and to scrape off any solid objects on that part of the valve plate which extends into the passage when the valve plate is retracted or partially retracted from the passage.

7. A valve according to claim 6, wherein the scraper blades are arranged to be replaced without dismantling the valve.

8. A valve according to claim 7, wherein the scraper blades are mounted in respective guide plates which are mounted in a replaceable manner in grooves in the housing.

9. A valve according to any one of claims 6 to 8, wherein the scraper blades are made of a resilient material.

10. A valve according to claim 6 or claim 7, wherein the scraper blades are mounted in guide bars which are rotatably mounted in the housing in a replaceable manner.

11. A valve according to claim 10, wherein the guide bars are acted on by resilient means to urge the scraper blades against the respective sides of the valve plate.

12. A valve according to claim 11, wherein the resilient means comprise a coil spring.

13. A valve according to any one of claims 10 to 12, wherein each scraper blade comprises a doctor blade of substantially rigid material.

14. A valve according to any one of claims 5 to 13, wherein grooves are provided in the edges of the valve plate to facilitate the flow of cleaning fluid through the housing.

15. A valve according to claim 14, wherein guide means are provided for guiding movement of the valve member between the open and closed positions of the valve and vice versa.

16. A valve according to claim 15, wherein the guide means are engageable in the grooves in the edges of the valve plate.

17. A valve according to any one of claims 2 to 16, wherein the housing is provided with a drain plug.

18. A valve according to any one of the preceding claims, wherein the valve member is arranged to be moved by pneumatic or hydraulic means such as a ram.

19. A valve substantially as described herein with reference to Figs. 1-4 of the drawings.

20. A valve substantially as described herein with reference to Figs. 5 and 6 of the drawings.