GB2511149A

GB2511149A - Liquid separator

Info

Publication number: GB2511149A
Application number: GB201313120A
Authority: GB
Inventors: Nigel R C Shepherd; Gary Deaville
Original assignee: Haigh Engineering Co Ltd
Current assignee: Haigh Engineering Co Ltd
Priority date: 2012-11-30
Filing date: 2013-07-23
Publication date: 2014-08-27
Also published as: GB201313120D0; IE20130361A1

Abstract

A method of operating a liquid separator having a rotor provided within a screening cage 112 provided within a housing 106. The housing having an input port 118 connectable to a source of waste water whereby waste water can be introduced into the screening cage. An output port is connectable to a liquid sink for decanting liquid from the housing after passing through the screening cage. The method includes the screening cage cleaning steps of partially filling the housing with waste liquid, establishing a fluid flow path between the output port and input port so liquid exiting the output port can enter the screening cage via the input port and rotating the rotor so as to circulate liquid through the screening cage and back to the interior of the screening cage. Advantageously the separator allows cleaning of the screening cage with little disruption to the normal operation of the separator.

Description

LIQUID SEPARATOR

This invention relates to liquid separators which include a housing, a screening cage having a rotor rotatably mounted within the cage, the housing having an input port through which waste water can be introducing into the screening cage and an output port through which water can be decanted from the housing after passing through the screening cage. The invention also relates to methods of operating such liquid separators.

Such separators separate solid waste from waste liquid, such as sewage or industrial effluent. The waste liquid is fed into the interior of the screening cage where the rotor by virtue of its rotation, urges the waste liquid through the walls of the screening cage. Solids greater than the mesh size of the screening cage, 3mm for example, are trapped on the inside of the screening cage whilst the liquid and smaller particles can pass through eventually to exit the housing via the output port.

The screening cage is configured so that there is also a general flow of waste water upwards, which tends to move trapped particles upwards towards a mechanical arrangement for moving the solids to the top of the screening cage for removal. A known configuration is as shown in Figure 1 in which the lower half of the screening cage is conical tapering outwards and upwards so urging waste liquid to flow upwards, by virtue of rotation of the rotor within screening cage, and an upper half of the screening cage which is also conical but tapers inwardly and upwards and having an internal spiral flange which pushes the solids upwards to the top of the screening cage (where it is ejected from the housing at an ejection port), again by virtue of the rotation of the rotor within the screening cage.

Not all the solids caught by the screening cage are able to be moved upwards for eventual ejection from the housing and hard fatty masses, for example, tend to stick to the mesh forming the screening cage which therefore has to be cleaned from time to time. A known method of cleaning is to construct the screening cage so it can be moved about a horizontal axis through an openable door in the housing to provide access to the interior of the screening cage via the open bottom end that, in use, is sealed to the input port of the housing. The inside of the screening cage can then be hosed with a high pressure water hose, for example, to clean the inside of the screening cage.

This cleaning operation is labour intensive, time consuming and generally requires protective wear and stringent safety precautions in cases where the waste liquid is potentially hazardous to human health. The structure of the liquid separator is also made more complex due to the need to manoeuvre the screening cage as described. The present invention seeks to provide a liquid separator that can be more readily cleaned, and a method of cleaning a liquid separator.

Accordingly, the present invention provides, in a first aspect a method of operating a liquid separator having a rotor provided in a screening cage provided within a housing, the housing having an input port connectable to a source of waste water whereby waste water can be introduced into the screening cage and an output port connectable to a liquid sink for decanting liquid from the housing after passing through the screening cage, the method comprising the screening cage cleaning steps of partially filling the housing with waste liquid; establishing a fluid flow path for reintroducing liquid at or adjacent the output port into the screening cage; and rotating the rotor within the screening cage so as to circulate liquid through the screening cage and back to the interior of the screening cage.

In normal operation these cleaning steps will be preceded by rotating the rotor while introducing waste water into the screening cage through the input port and decanting screened liquid from the housing through the output port and then closing the output port, i.e. the normal filtering operation of the separator, to partially fill the housing with liquid.

If, as will be usual, normal filtering is to be resumed or started, the input port is reconnected to the source of waste water and the output port is reconnected to the liquid sink.

The rotor within the screening cage may be rotated continuously with the normal filtering operation, cleaning steps and reversion to normal filtering operation successively carried out. Alternatively, the rotation of the rotor may be halted either before or after the cleaning steps are carried out, or both.

According to a further aspect of the present invention there is provided a liquid separator comprising: a rotor provided in a screening cage provided within a housing, the housing having an input port connectable to a source of waste water whereby waste water can be introduced into the screening cage, and an output port connectable to a liquid sink for decanting liquid from the housing after passing through the screening cage, the separator having a valve arrangement having three operative states; wherein in a first operative state, waste water can pass through the inlet port into the screening cage, and screened waste water can exit through the outlet port; wherein in a second operative state, waste water can pass through the inlet port into the screening cage, and screened waste water is prevented from exiting through the outlet port so that the housing fills with waste water; and wherein in a third operative state, waste water from the source of waste water is prevented from entering through the inlet port but liquid can re-circulate into the screening cage from within the housing that has passed through the screening cage, and screened waste water is prevented from exiting through the outlet port.

Preferably, the valve arrangement having an input conduit and an output conduit that can be configured to be in to any of: said first operative state in which the input port and output port are in fluid communication with the input conduit and the output conduit; said second operative state in which the input port is in fluid communication with the input conduit and the output port is closed; and said third operative state in which the output port is in fluid communication with input port whereby liquid exiting the output path can enter the screening cage via the input port.

The first operative state places the separator in its filtering state, the second operative position allows the housing to be filled with liquid to a desired level and the third operative position places the separator in its cleaning state.

The valve arrangement may comprise a valve having: a first valve member mounted to the housing and having a first pair of through-holes sealed to the input port and output port, respectively; a second valve member mounted to the first valve member and having a second pair of through-holes, forming at least part of the input and output conduits; and an intermediate valve member between the first and second valve member and movable relative thereto between three operative positions place the valve in the three operative states, respectively.

Other valve arrangements may be employed in the separator of the present invention, for example a member of interconnected distinct valves which can be selectively opened and closed to place the separator in the required operative states.

The intermediate valve member may have a third pair of through-holes which place the input port and input conduit and the output port and output conduit in fluid communication when in the first operative position; a fourth through-hole and a sealing region which place the input port and input conduit in fluid communication and to close the output port, respectively when the second position; and a trough which places the input port and output port in fluid communication when in the third position.

The intermediate valve member may be generally disc-shaped and rotatably mounted for rotation about a rotation axis between the input port and output port.

The trough of this embodiment may lie along a partial diameter of the intermediate portion including the rotation axes, the third pair of through-holes located diametrically opposite each other, and the fourth through-hole and sealing region located diametrically opposite each other.

Other forms of intermediate valve member may be employed, for example one which is translatable to the three operative positions having the third pair or through-holes, the fourth through-hole and sealing region, and the trough all arranged in a row.

The intermediate member may have a handle by which the intermediate member may be moved manually between its operative positions. Alternatively, it could be motor driven.

Preferably, in an alternate valve arrangement the invention comprises a first valve movable between two positions, a first position allowing fluid to pass through said inlet port into said screening cage only from a waste water supply and a second position allowing fluid to pass through said inlet port into said screening cage only from within said housing. In this manner, waste water is re-circulated within the separator.

Conveniently a second valve is provided which is coordinated to open and close the outlet valve with operation of the first valve.

The first and second valves are operated together to afford said three operative states; wherein in a first operative state, the first valve is in a first position to allow waste water to pass through the inlet port into the screening cage, and the second valve is an open position to allow screened waste water to exit through the outlet port; wherein in a second operative state, the first valve is in an first position to allow waste water to pass through the inlet port into the screening cage, and the second valve is a closed open position to prevent screened waste water exiting through the outlet port so that the housing fills with waste water; and wherein in a third operative state, the first valve is in a second position to prevent waste water to enter from the source of waste water but to allow liquid to re-circulate into the screening cage from within the housing that has passed through the screening cage, and the second valve is a closed position to prevent screened waste water exiting through the outlet port.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which; Figure 1 is a diagrammatic perspective view of a liquid separator according to the present invention; Figure 2 is a diagrammatic, cross sectional, end view of the separator of Figure 1; Figures 3 and 4 are schematic diagrams of a valve and component thereof useful with the present invention; Figures 5-7 are top views of the valve of Figure 3 in three operating positions; and Figures 8-10 show an alterative valve arrangement according to the present invention.

Referring to Figures 1 and 2 the illustrated apparatus 100 is a combination of a liquid separator 102 and compactor 104. Solid waste extracted from waste liquid by the liquid separator 102 is fed to the compactor where it is compacted to further remove liquid from the waste and to reduce its volume.

The liquid compactor 102 includes a housing 106 supported above floor level by a support frame 108. It has an inspection door 110 providing access to a screening cage 112 mounted inside the housing 106. The screening cage includes a rotor driven by the driven shaft 114 of a drive motor 116.

The housing 106 has at its base a centrally located input port 118 and an output port (not shown) offset from the input port. Waste waster introduced into the housing 106 flows into the interior of the screening cage 112 and screened liquid can exit the housing through the output port.

The screening cage 112 is about 600mm high and 300mm wide at its widest point. It has a lower, conical wall 120 of 3mm steel mesh and an upper, conical wall 122 also of 3mm mesh but additionally including a spiral ledge 124 about 0.5cm deep, both supported by a frame 1 26. When the rotor within the screening cage 112 is rotated by the motor 116, to about 960 rpm in this embodiment, the waste liquid is urged outwardly and upwardly so filtering the waste liquid as it passes through the mesh walls 120 and carrying solids filtered by the mesh upwards toward the top conical wall 122 whereafter, again due to the rotation by the motor 116, the spiral ledge 124 urges the solid material upward to be through an exit 128.

The liquid separator 102 also includes a valve arrangement 130 which will now be described with additional reference to Figures 3 to 7. It has a first valve member 132, secured and sealed to the underside of the base of the housing 106 by bolts (not shown) through the pair of attached flanges 134, a second valve member 136 and an intermediate valve member 138.

The first valve member has two through-holes 140, 142, which line up with the output port and input port 118 of the housing 106, respectively. The second valve member 136 also has two through-holes 144, 146 coaxially aligned with through-holes 140 and 142 and which together with tubes 148 and 1 50 form an input conduit and an output conduit.

The intermediate valve member 138 is rotatably mounted between the first valve member 1 32 and a second valve member 134 and has, as best seen in Figure 4, a pair of diametrically opposed through-holes 152 and 154, a further through-hole diametrically opposed to a sealing flat region 158, and a pair of hemispherical indentations 160 and 162 joined by a trough 164.

A handle 168 allows manual rotation of the intermediate valve member 138 to three operative positions as will now be described with particular reference to Figures 5 to 7.

When the intermediate member 138 is in a first operative position, as shown in Figure 5, the through-holes 140, 152 and 138 and are aligned as are through-holes 142, 1 54 and 140 so allowing waste liquid to be fed into the screening cage from a source of waste liquid coupled to inlet tube 150 and to screened liquid to exit the housing to tube 148 to a collection point. This is the normal operative position. When the intermediate member 138 is in a second operative position, as shown in Figure 6, the through-holes 142, 156 and 140 are aligned but through-hole 140 in the first valve member is sealed by the flat seal region 1 58 of the intermediate member. In this operative position the liquid cannot exit the housing so if waste liquid continues to enter the screening cage through the inlet tube 150 and inlet port of the housing it will fill up.

When the intermediate member is in a third operative position the hemispherical depressions 160 and 162 are aligned with the through-holes 140 and 142, respectively, the depressions 160 and 102 and trough 164 forming, in co-operation with the first valve member 132, an external flow path between the input port and output of the housing 106.

The liquid separator 100 is operated as follows.

The intermediate valve member is placed in the first operative position, and the motor 116 is started so rotating the screening cage 112. Waste water is then pumped into the screening cage via pipe 1 70 connected to inlet tube 150 of the valve 130.

The waste liquid is filtered with screened water leaving the housing 106 via the output port to a pipe 1 72 connected to outlet tube 148 of the valve 130 and solid waste being raised to the top of the screening cage for ejection through port 128 as previously described.

When the screening cage is to be cleaned, the intermediate valve member 138 is placed in the second operative position and the housing partially filled with waste liquid, for example until level with the top of conical wall 120 of the screening cage 106.

Once the housing filled to the desired level the intermediate valve member is placed in the third operative position. Rotation of the rotor within the screening cage causes circulation of the waste water out of the housing and back into the housing and the turbulence acts to dislodge material from the screening cage placing it in suspension.

After a desired cleaning period the intermediate valve member is then moved back to the first operative position whereafter normal operation of the liquid separator resumes.

It can be seen that the apparatus and method of the present invention allow cleaning of the screening cage with little disruption to the normal operation of the separator.

A liquid other than waste liquid could be used to partially fill the housing for the cleaning operation, if necessary to clean same particular waste material.

The valve could be motor driven rather than manual. By also including remotely controllable valves in the pipes connected to waste liquid, cleaning liquid and, if used, and the screened water disposal region a fully automated system could be provided with use of a suitable control system connected to control such valves and the motor 116.

In this connection a further embodiment of the separator is shown in Figures 8 to 10. In Figures 8 to 10, an alternative form of valve arrangement is shown, which achieves a similar flow characteristic to the valve arrangement shown in Figures 5 to 7.

Figure 8 shows a cross sectional view of a liquid separator 200, again having a housing 201, and a screening cage 202 within which is mounted at rotor 203.

The housing includes an input port 204 and an output port 205. As with the above embodiment, waste water is introduced via input port 204 into the screening cage. In order to access the screening cage, the waste water passes through a slidable valve 206. Under the control of a piston driven assembly 207, a slidable valve element 208 is moveable between first and second positions to perform two operations, namely in a first position it allows access of waste water from the inlet port to the screening cage and prevents recirculation of waste water from at or adjacent the outlet (decant) port 205. In its second position, the slidable valve element moves to close access of waste water from the inlet port 204 to the screening cage whilst at the same time opening a path for waste water to recirculate from at or adjacent the outlet port 205 back into the screening cage.

A pivoting valve 209 opens and closes to allow water to pass through to the outlet valve 205 from within the housing.

The slidable valve 206 and pivoting valve 209 work together to perform three operations. In a first operation, as shown in Figure 8, the normal running mode of the separator, the slidable valve is in its first position, allowing waste water to flow from the inlet port 204 into the screening cage, whilst at the same time preventing recirculation of waste water that has passed through the screening cage to an area at or adjacent the outlet port 205 back into the screening cage.

The pivoting valve 209 is in an open position allowing waste water to be decanted out of the separator.

Figure 9 shows a second operation, where the slidable valve 206 is still in its first position, but the pivoting valve is closed, so that the housing fills with waste water.

In a third operation, as shown in Figure 10, the slidable valve 206 is moved to its second position, whereby the inlet of further waste water from the inlet port 204 is prevented but waste water at or adjacent the outlet port can be re-circulated through to the interior of the screening cage via a inlet 210 created by the sliding valve 206. The screening cage is cleaned due to the effect of the re-circulating water dislodging material caught in the cage and placing it in suspension, which can then be decanted once the slidable valve and pivoting valves are repositioned back to their positions for the first operation.

Operation of the respective slidable and pivoting valves can be coordinated to optimize the efficiency of the separator.

Claims

Claims: 1. A method of operating a liquid separator having a rotor provided in a screening cage provided within a housing, the housing having an input port connectable to a source of waste water whereby waste water can be introduced into the screening cage and an output port connectable to a liquid sink for decanting liquid from the housing after passing through the screening cage, the method comprising the screening cage cleaning steps of: partially filling the housing with waste liquid; establishing a fluid flow path for reintroducing liquid at or adjacent the output port into the screening cage; and rotating the rotor within the screening cage so as to circulate liquid through the screening cage and back to the interior of the screening cage.
2. The method of claim 1, in which the cleaning steps of claim 1 are preceded by rotating the rotor while introducing waste water into the screening cage through the input port and decanting screened liquid from the housing through the output port and then closing the output port to partially fill the housing with liquid.
3. The method of claim 1 or 2, in which, after the cleaning steps of claim 1, the input port is reconnected to the source of waste water and the output port is reconnected to the liquid sink.
4. The method of any one of claims 1 to 3 in which the rotor is rotated continuously.
5. The method of any one of claims 1 to 4, further comprising a first valve movable between two positions, a first position allowing fluid to pass through said inlet port into said screening cage only from a waste water supply and a second position allowing fluid to pass through said inlet port into said screening cage only from within said housing.
6. The method of any of claims 1 to 5, further comprising a second valve which is coordinated to open and close the outlet valve with operation of the first valve.
7. The method of claim 6, wherein the first and second valves are operated together to afford three operative states; wherein in a first operative state, the first valve is in a first position to allow waste water to pass through the inlet port into the screening cage, and the second valve is an open position to allow screened waste water to exit through the outlet port; wherein in a second operative state, the first valve is in an first position to allow waste water to pass through the inlet port into the screening cage, and the second valve is a closed open position to prevent screened waste water exiting through the outlet port so that the housing fills with waste water; and wherein in a third operative state, the first valve is in a second position to prevent waste water to enter from the source of waste water but to allow liquid to re-circulate into the screening cage from within the housing that has passed through the screening cage, and the second valve is a closed open position to prevent screened waste water exiting through the outlet port.
8. A liquid separator comprising: a rotor provided in a screening cage provided within a housing, the housing having an input port connectable to a source of waste water whereby waste water can be introduced into the screening cage, and an output port connectable to a liquid sink for decanting liquid from the housing after passing through the screening cage, the separator having a valve arrangement having three operative states; wherein in a first operative state, waste water can pass through the inlet port into the screening cage, and screened waste water can exit through the outlet port; wherein in a second operative state, waste water can pass through the inlet port into the screening cage, and screened waste water is prevented from exiting through the outlet port so that the housing fills with waste water; and wherein in a third operative state, waste water from the source of waste water is prevented from entering through the inlet port but liquid can re-circulate into the screening cage from within the housing that has passed through the screening cage, and screened waste water is prevented from exiting through the outlet port.
9. A liquid separator as claimed in claim 8, wherein the valve arrangement comprises an input conduit and an output conduit that can be configured to be in to any of: said first operative state in which the input port and output port are in fluid communication with the input conduit and the output conduit; said second operative state in which the input port is in fluid communication with the input conduit and the output port is closed; and said third operative state in which the output port is in fluid communication with input port whereby liquid exiting the output path can enter the screening cage via the input port.
10. A liquid separator as claimed in claim 9, in which the valve arrangement comprises a valve having: a first valve member mounted to the housing and having a first pair of through-holes sealed to the input port and output port, respectively; a second valve member mounted to the first valve member and having a second pair of through-holes, forming at least part of the input and output conduits; and an intermediate valve member between the first and second valve member and movable relative thereto between three operative positions place the valve in the three operative states, respectively.
11. The liquid separator of claim 10, in which the intermediate valve member has; a third pair of through-holes which place the input port and input conduit and the output port and output conduit in fluid communication when in the first operative position; a fifth through-hole and a sealing region which place the input port and input conduit in fluid communication and to close the output port, respectively, when the second position; and a trough which places the input port and output port in fluid communication when in the third position.
12. The liquid separator as claimed in claim 10 or 11, in which the intermediate valve member is generally disc-shaped and rotatably mounted for rotation about a rotation axis between the input port and output port.
13. The liquid separator of claim 11, in which the trough lies along a partial diameter of the intermediate portion including the rotation axes, the third pair of through-holes are located diametrically opposite each other, and the fourth through-hole and sealing region are located diametrically opposite each other.
14. The liquid separator of any one of claims 10 to 13, in which the intermediate member has a handle by which the intermediate member may be moved manually between its operative positions.
1 5. The liquid separator of claims 8, further comprising a first valve movable between two positions, a first position allowing fluid to pass through said inlet port into said screening cage only from a waste water supply and a second position allowing fluid to pass through said inlet port into said screening cage only from within said housing.
16. The liquid separator of claim 15, further comprising a second valve which is coordinated to open and close the outlet valve with operation of the first valve.
1 7. The liquid separator of claim 16, wherein the first and second valves are operated together to afford three operational states;
18. A method of operating a liquid separator substantially as hereinbefore described with reference to and/or as shown in, the accompanying drawings.

1 9. A liquid separated substantially as hereinbefore described with reference to and/or as shown in, the accompanying drawings.