GB2269115A

GB2269115A - Drive mechanism for settling tank or mixer

Info

Publication number: GB2269115A
Application number: GB9313919A
Authority: GB
Inventors: John Brian Gray
Original assignee: WEAVERBROOK Ltd
Current assignee: WEAVERBROOK Ltd
Priority date: 1992-07-29
Filing date: 1993-07-06
Publication date: 1994-02-02
Anticipated expiration: 2013-07-06
Also published as: GB2269115B; GB9313919D0

Abstract

An electric linear induction motor provides a contactless motive force which rotates mixing paddles (Fig.1) or moves a surface skimming blade 38 and/or floor scraping blade in a settling tank. In Fig. 6 blade 38 is suspended from a radial arm 35 which is rotated round a circular tank, to urge floating matter over a weir 32 by the reaction force between a linear thrust unit 37, supplied with electric power, and a fixed annular reaction plate 31 on the tank wall. Blade 38 may be replaced by or combined with a second blade sweeping settled solids towards the centre of the tank. In Figs 3, 4 a truly linear drive moves a skimming blade alternately in two directions along a rectangular tank. In Fig. 1 mixing paddles are mounted on a shaft which carries an annular reaction plate and rotated by a thrust unit fixed above the plate. This arrangement, with the thrust unit fixed and the reaction plate moving, may be applied in Figs. 3-6 equally well. <IMAGE>

Description

Fluid Treatment APparatus This invention relates to fluid treatment apparatus.

Water collected in reservoirs etc has to undergo several stages of treatment before it is rendered potable. The water industry lays down strict guidelines covering contamination of potable water, and therefore it is important that lubricating fluids from the treatment apparatus do not contaminate the water. Conventional fluid treatment apparatus are usually mounted outdoors and comprise a movable arm mounted above a tank containing the water to be treated, the arm being provided with e.g. an agitating paddle or a skimmer depending upon the treatment being carried out. The arm is rotated or driven across the tank by a motor having its rotary output shaft connected to a drive mechanism. These motors and drive mechanisms require regular lubrication and are prone to wear.

We have now devised a fluid treatment apparatus which alleviates the problems with conventional fluid treatment apparatus.

In accordance with this invention there is provided a fluid treatment apparatus comprising a tank for holding the fluid to be treated, a movable member mounted above the tank and connected to an implement arranged to contact the fluid to be treated, and a linear motor arranged to drive the movable member relative to the tank.

A linear motor is a particular form of electrical induction motor in which the stator and rotor are linear and substantially parallel instead of cylindrical and coaxial. The stator or drive unit is connected to an electrical supply so that a moving electromagnetic field is set up. The electromagnetic field acts on a flat rotor or reaction plate to induce relative movement between the two parts.

The movable member may be connected to a rotatably mounted shaft so that when the motor is energised the shaft is driven about its axis in order to rotate the implement.

Alternatively the movable member may be mounted for linear movement so that the implement is driven linearly.

The implement may comprise a paddle or the like immersed in the fluid e.g. for mixing or agitating the fluid.

Alternatively the implement may comprise a skimming element such as a blade or vane in contact with the surface of the fluid e.g. for removing scum and other surface debris from the fluid. The implement may instead comprise a blade or vane mounted adjacent the base of the tank and arranged to move sediment on the base of the tank to a collection duct.

Preferably the base of the tank is conical, the collection duct being mounted at the lowermost part of the base.

The fluid treatment apparatus may be provided with a combination of implements so that different types of treatments can be carried out simultaneously on the fluid.

Preferably the reaction plate is fixed to the tank and acts as a support for the movable member, with the stator or thrust unit of the motor mounted on the movable member.

Alternatively the thrust unit may be fixed relative to the tank and the reaction plate mounted on the movable member.

Preferably means are provided for maintaining a constant spacing between the thrust unit and the reaction plate.

The arrangement of the linear motor to provide drive alleviates the need for the complicated drive chains and gearboxes used in conventional fluid treatment apparatus.

Furthermore, no lubrication is required and no wear occurs because there is no direct drive connection between the movable member and the tank.

Also in accordance with this invention as seen from a second aspect, there is provided a skimming apparatus comprising a linear motor thrust unit arranged to supply a contactless motive force to a reaction plate of the linear motor in order to drive a skimming assembly.

The thrust unit is preferably mounted to a stationary object, the reaction plate being mounted to the skimming assembly. Alternatively the thrust unit may be mounted to the skimming assembly, the reaction plate being mounted to a stationary object.

The reaction plate is preferably linear so that the skimming assembly is driven linearly. Alternatively the reaction plate may be annular so that the skimming assembly is rotated.

Also, in accordance with this invention as seen from a third aspect, there is provided a mixing/agitating apparatus comprising an assembly having a linear motor thrust unit arranged to supply a contactless motive force to an annular reaction ring of the linear motor in order to drive a rotatable shaft about its axis, a mixing/agitating implement being fixed to the shaft.

Embodiments of this invention will now be described by way of examples only and with reference to the accompanying drawings, in which: Figure 1 is a side view of a drive assembly of a mixing/agitating apparatus in accordance with this invention Figure 2 is a plan view of the drive assembly of Figure 1; Figure 3 is a side view of a drive assembly of a skimming apparatus in accordance with this invention; Figure 4 is a plan view of the drive assembly of Figure 3; Figure 5 is a plan view of an alternative embodiment of skimming apparatus in accordance with this invention; and Figure 6 is a sectional view along the line VI - VI of Figure 5.

Referring to Figures 1 and 2 of the drawings there is shown a drive assembly of a mixing/agitating apparatus comprising a vertical shaft 10 rotatably mounted to a support 12 by a pair of bearings 11. The lower end of the shaft is provided with a pair of paddles (not shown) immersed in the tank of water being treated. An annular reaction plate 13 is concentrically mounted to the shaft 10 by radially extending spokes 14. A linear motor thrust unit 15 is mounted to the support 12 and is arranged face-to-face with the reaction plate 13. An air gap is maintained between the thrust unit 15 and the annular reaction plate 13 by an automatic adjusting mechanism (not shown).

In use, the trust unit 15 is connected to an electrical supply top produce a moving electromagnetic field which acts upon the reaction plate 13, to produce linear thrust. The linear thrust serves to drive the plate and thus turn the shaft 10 about its axis, so that the paddles agitate and mix the water in the tank.

Referring to Figures 3 and 4, there is shown a drive assembly of a skimming apparatus arranged to remove scum and other surface debris from the water being treated. The apparatus comprises an elongate vane 20 which extends across the width of the tank of water. The vane 20 is suspended from a framework 24 by a pair of pivots 22. The framework 24 is slidably mounted at its opposite ends on elongate rails 21, 23 which extend longitudinally along the side walls of the tank of water. The rail 23 acts as a reaction plate for a thrust unit 25 mounted to the framework 24. In use, the thrust unit is energised to drive the assembly along the tank of water.

The base 20 is in contact with the surface of the water and acts to sweep scum and other debris to one end of the tank for collection. At that end of the tank the vane 20 is raised and the assembly then reverses back along the tank so that the process can be repeated. Several such vanes may be arranged to travel in succession along the tank.

Referring to Figures 5 and 6, there is shown a rotary skimming apparatus comprising a tank of water having a circular outer wall 30. An annular reaction plate 31 is mounted on the top surface of the outer wall 30. An inner wall 32 is arranged concentrically inside the outer wall 30 and contains the water 33 being treated. An annular trough 34 is formed between the inner and outer walls 32, 30 so that scum and other debris can be skimmed off the surface of the water and into the trough 34. An arm 35 is rotatably pivotally attached to a support tripod 36 mounted in the centre of the tank. A thrust unit 37 is mounted on the end of the arm 35 in face-to-face relationship with the reaction plate 31. A curved vane 38 is suspended from the arm 35 so that it contacts the surface of the water.

In use, the thrust unit 37 is energised so that the arm 35 is driven in the direction of the arrow D. The curved vane 38 sweeps any scum or other surface debris radially outwards towards the trough 34 for collection.

In an alternative embodiment, the vane may be mounted against the base of the tank so that when the thrust unit is energised sediment is swept towards the centre of the tank.

A pump is connected to a duct in the centre of the base of the tank so that the sediment can be removed. The base of the tank may be conical so as to promote the flow of sediment towards the duct. A second vane may be arranged to simultaneously remove scum and other surface debris from the surface of the water.

Claims

1) A fluid treatment apparatus comprising a tank for holding the fluid to be treated, a movable member mounted above the tank and connected to an implement arranged to contact the fluid to be treated, and a linear motor arranged to drive the movable member relative to the tank.

2) A fluid treatment apparatus as claimed in claim 1 in which the movable member is connected to a rotatably mounted shaft.

3) A fluid treatment apparatus as claimed in claim 1 in which the movable member is mounted for linear movement.

4) A fluid treatment apparatus as claimed in any preceding claim in which the implement comprises a paddle or the like arranged for immersion in the fluid to be treated.

5) A fluid treatment apparatus as claimed in any of claims 1 to 3 in which the implement comprises a skimming element arranged to contact the surface of the fluid to be treated.

6) A fluid treatment apparatus as claimed in any of claims 1 to 3 in which the implement comprises a vane or the like mounted adjacent the base of the tank and arranged to move sediment on the base of the tank to a collection duct.

7) A fluid treatment apparatus as claimed in claim 6 in which the base of the tank is conical, the collection duct being mounted at the lowermost part of the base.

8) A fluid treatment apparatus as claimed in any preceding claim in which the reaction plate of the linear motor is fixed to the tank and the thrust unit is mounted on the movable member.

9) A fluid treatment apparatus as claimed in any of claims 1 to 7 in which the thrust unit of the linear motor is fixed to the tank and the reaction plate of the linear motor is mounted on the movable member.

10) A fluid treatment apparatus as claimed in any preceding claim in which means are provided for maintaining a constant spacing between the thrust unit and reaction plate of the linear motor.

11) A skimming apparatus comprising a linear motor thrust unit arranged to supply a contactless motive force to a reaction plate of the linear motor in order to drive a skimming assembly.

12) A skimming apparatus as claimed in claim 11 in which the thrust unit is mounted to a stationary object, and the reaction plate is mounted to the skimming assembly.

13) A skimming apparatus as claimed in claim 11 in which the thrust unit is mounted to the skimming assembly, and the reaction plate is mounted to a stationary object.

14) A skimming apparatus as claimed in any of claims 11 to 13 in which the reaction plate is linear.

15) A skimming apparatus as claimed in any of claims 11 to 13 in which the reaction plate is annular.

16) A mixing/agitating apparatus comprising an assembly having a linear motor thrust unit arranged to supply a contactless motive force to an annular reaction ring of the linear motor in order to drive a rotatable shaft about its axis, a mixing/agitating implement being fixed to the shaft.

17) A fluid treatment apparatus substantially as herein described with reference to the accompanying drawings.