GB2389060A

GB2389060A - Sludge and slurry agitation/mixing apparatus with timed opening of air valves

Info

Publication number: GB2389060A
Application number: GB0306781A
Authority: GB
Inventors: Norman Watson
Original assignee: SLURRY AERATION MAN SYSTEMS LT
Current assignee: SLURRY AERATION MAN SYSTEMS LT
Priority date: 2002-03-27
Filing date: 2003-03-25
Publication date: 2003-12-03
Anticipated expiration: 2023-03-25
Also published as: GB0306781D0; GB2389060B; GB0207147D0

Abstract

An agitation/mixing apparatus for sludge and slurry or the like has at least two pipes 3, 5, 7 ,9 each having at least one outlet aperture 21 disposed in a tank or other holder 1 for accommodating the sludge/slurry. An air supply means 23 is connected to the pipes and control means is provided to automatically control the supply of air under pressure to each pipe in turn on a sequential basis for a predetermined period of time. The control means comprises a valve 13,15, 17,19 for each pipe and timing means 27 to control opening and closing of the valves such that each valve in turn is closed after opening of the succeeding valve in the sequence. A non-return valve which may be used in the above apparatus has a hollow body 51 having at least one aperture 53 in its peripheral wall. One end of the hollow body is connected to a supply of air and the other end 55 is blanked off. A silicone rubber sleeve 57 is fitted over the hollow body and is a close sliding fit. Internal pressure of air forces the sleeve away from the apertures and the air travels under sleeve 7 and emerges as bubbles. In its rest position or under external pressure the sleeve 7 seals all the apertures and thereby acts as a non-return valve.

Description

Title: Improvements in or relating to slurry/sludge anitation/mixinn

systems DESCRIPTION

The present invention relates to slurry/sludge agitating/mixing systems and to components for use in such systems.

It is known that it is beneficial to agitate sludge or slurry of animal or human waste. For example, agitating human waste improves the operation of the bacteria and also allows more water to be removed. The latter is advantageous as it means that the ratio of solid to water is greatly increased, thereby making subsequent disposal of the sludge more economical as less water has to be transported.

One known method of agitating the slurry/sludge is to introduce air under pressure into the slurry/sludge. A particularly advantageous arrangement results where the air is introduced into the slurry/sludge through a plurality of outlet apertures and where those outlets are supplied with air in a sequential manner. i.e. some outlets are emitting air whilst others are not. A valve system is used to control which outlets are supplied with air at any one time. Such a system is disclosed in GB patent 1568813.

The present invention provides an improvement.

Accordingly, a first aspect of the invention provides an agitation/mixing apparatus for sludge, slurry or the like comprising at least two pipes which each have at least one outlet aperture disposed in a tank or other holder for accommodating the sludge/slurry, an air supply means connected to the pipes to

supply air under pressure to the pipes to emerge from the outlet apertures, and control means to automatically control the supply of air under pressure from the air supply means to each pipe in turn on a sequential basis for a predetermined period of time, and in which the control means comprises a valve for each pipe and timing means to control opening and closing of the valves, and wherein the closing of each valve in turn is performed after opening of the succeeding valve in the sequence.

This overlapping of the valve opening and closing sequence is advantageous as it avoids imposing excessive back loads on the pump because it avoids over pressurization of the system. Furthermore, the momentary reduction in air flow from the outlets is believed to further assist the mixing and agitation process. The timing of the opening and closing of the valves may be controlled electronically, for example, in conjunction with programmable control means. However, we prefer to use a mechanical cam timing system to time the opening and closing relation of the respective valves. The cam operates micro switches which are adjustably positionable with respect to the cam. There is a micro switch for each valve. The cam is driven by an electric motor. The motor drives through a gear box. Electrically operated valves are employed whereby operation of each micro switch triggers operation of the respective valve to move it between its open and closed position to control the supply of air to the associated pipe.

Each pipe has a plurality of outlet apertures which may be disposed in branches of the pipework. Each outlet aperture is provided with a nonreturn

valve to prevent sludge/slurry and particulate material from being drawn into the pipe system through the outlet aperture.

A convenient and simple form of non-return valve that has been used in the past comprise a flattened tube of rubber, one end of which is dimensioned to fit on to the end of a pipe and the other end comprises a slit through which the air can emerge when under pressure. The flattened end comprising two overlaying pieces of rubber secured together along their opposite edges acts as a one way valve when the air supply is terminated. The closing action is aided by the weight of slurry/sludge acting on the rubber.

This construction necessitates having numerous branches in the pipework to provide the necessary number of ends on to which the non-return valve is fitted. The presence of particulate material in the slurry/sludge accumulates around the outlet valves and can reduce their working life by increasing wear. Another aspect of the invention proposes a construction of one way valve which avoids the above problem.

Accordingly, another aspect of the invention provides a one way valve comprising a hollow tubular body having an air inlet and at least one aperture in a peripheral wall thereof, and further comprising a flexible sleeve fitted over the tubular body in a position to overlie said at least one hole and extending along the tubular body away from said at least one aperture, and wherein the fit of the sleeve on the tubular body, serves to allow fluid to pass out from the tubular body via said at least one aperture whilst inhibiting the passage of material and/or fluid flow in the reverse direction.

Preferably silicon rubber is used for the sleeve. Preferably the tubular body has an outer periphery that is circular, at least over the area where the sleeve is fitted. The sleeve is dimensioned to be a close sliding fit onto the outer periphery of the tubular body. The flexibility of the material ensures that the said at least one aperture is closed off by contact of the sleeve with the tubular body in the absence of air under pressure. One end of the tubular body is adapted for connecting to the aforesaid pipe system. It may be glued in place or fitted using a screw connection. Preferably, the other end is blanked off or fitted with a blanking plug.

We prefer to have a plurality of apertures disposed in said peripheral wall.

Their total area is preferably equal to the area of the internal bore of the tubular body. Preferably, the pipework of the system and the base of the tubular body have the same area and usually will have the same diameter. Preferably, the plurality of apertures are disposed in a common plane disposed normally to the axis of the tubular body. Preferably four apertures are provided spaced at 90 apart around the peripheral wall. Exceptionally, they may be disposed in an axially staggered formation.

The present invention will now be described further, by way of example only, with reference to the accompanying drawings; in which: Figure 1 is a schematic layout of a slurry/sludge mixing/agitation system according to the present invention.

Figure 2 is a sectional side view of a one way valve according to the invention, and

( Figure 3 is a sectional view taken on line A-A of Figure 2.

Referring firstly to figure 1, a tank for holding slurry or sludge is shown at 1. It is shown as circular, but can take any form. A pipe system is installed in the tank and is preferably disposed at or adjacent the bottom of the tank. In the illustrated example, the pipe system is made up of four pipe lines 3, 5, 7, 9 that connect to a distribution manifold 11 by way of respective valves 13, 15, 17, 19.

Air under pressure is supplied to the manifold from a blower 23. We prefer to use a roots type blower, but other types of blower/compressor can be used.

The pipe lines 3, 5, 7, 9 connect to a respective branch manifold, 3', 9', 7', 9', and each of these has a plurality of branch lines 11 connected thereto.

Eighteen in the illustrated embodiment. There is an air outlet 21 at the end of each branch line. The outlet is provided with a non-return valve which is preferably of the type described hereinafter with respect to figures 2 and 3, but may be of any other type.

The aforesaid valves 13, 15, 17, 19 are electronically operated magnetic/solenoid valves, and the signal to control their opening and closing is provided by the activation of micro switch 33, 35, 37, 39. I.e. one for each valve.

Power to the micro switches is from a power source controller, not illustrated.

Operation of the micro switch is controlled by a cam 27 which is driven at the desired speed by an electric motor 29 driving through a gear box 31.

The cam has a cam profile for each valve so that the opening and closing relation of the valves with respect to one another is controlled individually whilst being inter-related.

The cam profile is such that the four valves are opened in sequence one after the other on a cyclical basis. When a valve is opened air is supplied to the associated pipe line and to the respective branch lines to emerge from the outlets 21. However, before the next valve in the sequence to open is opened, the succeeding valve is closed. Thus there will be a short period of time when air emerges from the outlets of two of the pipe lines.

The time for which each value is opened and closed is determined by the speed of rotation of the cam and its cam profile.

Referring now to figures 2 and 3, a novel design of non-return valve is illustrated. It comprises a tubular body 51 that has four through apertures 53 formed in its peripheral wall. They are set 90 apart and disposed on a common diametrical plane. The area of the four apertures is substantially equal to the area of the internal bore of the tubular body. One end 55 of the tubular body is shown blanked off and the other end is provided with an external thread to facilitate attachment to a pipe system supplying air thereto - as used in the slurry/sludge agitation system described above. A silicone rubber sleeve 57 is fitted onto the exterior of the tubular body. The two components are so dimensioned that the sleeve is a close sliding fit onto the tubular body. As will be seen the sleeve has an axial length extending away from apertures 53. The sleeve is resiliently flexible.

When used in the aforedescribed system the arrangement is such that air passes out of the apertures 53 and travels in the space between the interior of the sleeve and the exterior of the tubular body. The space is created by resilient

( expansion and/or deflection of the sleeve under the air pressure. The air emerges from the opposite ends of the sleeve. The fit of the sleeve on the tubular body, its resilient properties, the number and size of the apertures 53 and the length of the sleeve is chosen so that where the air emerges from the opposite ends of the sleeve it preferably forms one large bubble.

When the air supply is turned off, the fit of the sleeve on the tubular body acts to inhibit the flow of fluid and/or particulate material in the reverse direction.

Claims

( CLAIMS

1. An agitation/mixing apparatus for sludge, slurry or the like comprising at least two pipes which each have at least one outlet aperture disposed in a tank or other holder for accommodating the sludge/slurry, an air supply means connected to the pipes to supply air under pressure to the pipes to emerge from the outlet apertures, and control means to automatically control the supply of air under pressure from the air supply means to each pipe in turn on a sequential basis for a predetermined period of time, and in which the control means comprises a valve for each pipe and timing means to control opening and closing of the valves, and wherein the closing of each valve in turn is performed after opening of the succeeding valve in the sequence.

2. An apparatus as claimed in claim 1 in which the timing of the opening and closing of the valves is controlled electronically in conjunction with programmable control means.

3. An apparatus as claimed in claim 1 and further comprising a mechanical cam timing system to time the opening and closing relation of the respective valves.

4. An apparatus as claimed in claim 3 in which the cam operates micro switches which are adjustably positionable with respect to the cam.

5. An apparatus as claimed in claim 4 in which there is a micro switch for each valve.

6. An apparatus as claimed in claim 3, 4 or 5 in which the cam is driven by

( an electric motor.

7. An apparatus as claimed in claim 6 in which the motor drives through a gear box.

8. An apparatus as claimed in any one of the preceding claims in which electrically operated valves are employed whereby operation of each micro switch triggers operation of the respective valve to move it between its open and closed position to control the supply of air to the associated pipe.

9. An apparatus as claimed in any one of the preceding claims in which each pipe has a plurality of outlet apertures which are be disposed in branches of the pipework and each outlet aperture is provided with a nonreturn valve to prevent sludge/slurry and particulate material from being drawn into the pipe system through the outlet aperture.

10. An apparatus as claimed in claim 9 in which the non-return valve comprises a flattened tube of rubber, one end of which is dimensioned to fit on to the end of a pipe and the other end comprises a slit through which the air can emerge when under pressure.

11. An apparatus as claimed in any one of claims 1 to 8 in which on or more of the outlet apertures is provided in a hollow tubular body having at least one aperture in a peripheral wall thereof, and wherein a nonreturn valve is formed by a flexible sleeve fitted over the tubular body in a position to overlie said at least one aperture and extending along the tubular body away from said at least one aperture, and wherein the fit of the sleeve on the tubular body, serves to allow fluid to pass out from the tubular body via said at least one aperture whilst

inhibiting the passage of material and/or fluid flow in the reverse direction.

12. An apparatus as claimed in claim 11 in which silicon rubber is used for the sleeve.

13. An apparatus as claimed in claims 10 or 11 in which the tubular body has an outer periphery that is circular, at least over the area where the sleeve is fitted.

14. An apparatus as claimed in any one of claims 11 or 13 in which the sleeve is dimensioned to be a close sliding fit onto the outer periphery of the tubular body.

15. An apparatus as claimed in any one of claims 11 to 13 in which there are a plurality of apertures disposed in said peripheral wall.

16. An apparatus as claimed in claim 15 in which the total area of the plurality of apertures at each valve location is equal to the area of the internal bore of the tubular body.

17. An apparatus as claimed in claim 15 or 16 in which the plurality of apertures are disposed in a common plane disposed normal to the axis of the tubular body.

18. An apparatus as claimed in claim 15, 16 or 17 in which four apertures are provided spaced at 90 apart around the peripheral wall.

19. An apparatus as claimed in claimed in claim 15 or 16 in which the plurality of apertures are disposed in an axially staggered formation.

20. An apparatus constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings of

( figure 1 or as modified according to figures 2 and 3.

21. A one way valve comprising a hollow tubular body having an air inlet and at least one aperture in a peripheral wall thereof, and further comprising a flexible sleeve fitted over the tubular body in a position to overlie said at least one aperture and extending along the tubular body away from said at least one aperture, and wherein the fit of the sleeve on the tubular body, serves to allow fluid to pass out from the tubular body via said at least one aperture whilst inhibiting the passage of material and/or fluid flow in the reverse direction.

22. A non-retum valve as claimed in claim 21 in which silicon rubber is used for the sleeve.

23. A non-retum valve as claimed in 21 and 22 in which the tubular body has an outer periphery that is circular, at least over the area where the sleeve is fitted.

24. A non-return valve as claimed in any of claims 21, 22 or 23 in which the sleeve is dimensioned to be a close sliding fit onto the outer periphery of the tubular body.

25. A non-return valve as claimed in claims 21 to 24 in which one end of the tubular body is adapted for connecting to a pipe system.

26. A non-return valve as claimed in claim 25 in which the other end of the tubular body is blanked off.

27. A non-retum valve as claimed in any one of claims 21 to 26 in which a plurality of apertures are disposed in said peripheral wall.

28. A non-return valve as claimed in claim 27 in which the total area of the

plurality of apertures at each valve location is equal to the area of the internal bore of the tubular body.

29. A non-retum valve as claimed in claim 27 or 28 in which the plurality of apertures are disposed in a common plane disposed normal to the axis of the tubular body.

30. A non return valve as claimed in claim 29 in which the plurality of apertures are disposed in an axially staggered formation.

31. A non-return valve as claimed in any one of claims 27 to 30 in which four apertures are provided spaced at 90 apart around the peripheral wall.

32. A non-return valve constructed and arranged substantially as hereinbefore described with reference to and as illustrated in figures 2 and 3.