ZA200707634B

ZA200707634B - Submersible mixer

Info

Publication number: ZA200707634B
Application number: ZA200707634A
Authority: ZA
Inventors: Swart Mathys Johannes
Original assignee: Swart Mathys Johannes
Priority date: 2007-09-05
Filing date: 2007-09-05
Publication date: 2008-10-29
Also published as: DE102008045887B4; DE102008045887A1; SE0801900L; SE533297C2

Description

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FIELD OF THE INVENTION 007/97 634

This invention lies in the field of submersible mixers for applications in a range of industries and processing plants, including sewerage treatment plants. )

Mixers used in a wide variety of applications tend to be one of two types, one where the motor is kept above the liquid surface and one where the motor is submerged with the mixer vanes.

BACKGROUND

Submersible mixers either have a direct connection of the motor to the impeller shaft or a reduction connection, like a gear train, to provide a suitable speed reduction from the motor to the impeller. In both cases difficulties have been experienced in sewerage plant applications, especially where the plant serves industrial sources. The inventor had discerned that reaction thrust generated by the impeller has led to internal damage to the components of the mixer and failure of water seals has also been implicated, in the inventor's opinion. The operational function of a mixer is the agitation and mixing of particles that tend to settle or sag in a suspension.

THE INVENTION

A mixer in accordance with this invention characterised by a thrust bearing located in the impeller shaft and preloaded by a co-acting bearing, has the thrust bearing located at a proximal position of the shaft and the preload bearing at a distal position on the shaft, with means for applying a preload provided on the shaft adjacent the preload bearing.

A mixer in accordance with this invention characterised by a thrust bearing located in the impeller shaft and preloaded by a co-acting bearing, has the thrust bearing located at a distal position of the shaft and the preload bearing )

at a proximal position on the shaft, with means for applying a preload provided on a housing in which the bearings are housed, adjacent the preload bearing.

The proximal position of the shaft is that nearer the impeller that is mounted on the shaft and the distal position the more remote position.

In accordance with a preferred embodiment of the invention the mixer has sealing means against ingress of liquid (usually water based liquids) located inside the housing of the mixer. The sealing means may comprise a primary seal and a secondary seal, the latter consisting of a spring activated seal.

Location of the sealing means inside the housing protects it against disruption which tends to occur especially in the cases of sewerage plants that serve. industry.

Preferably the means for applying a preload is a screw threaded appliance.

In accordance with an embodiment of the invention the impeller shaft is connected to the motor by a reduction connection that comprises a toothed belt drive, the drive constituted by a pulley on the impeller shaft and a pulley on the motor shaft with a connecting housing that allows threading the belt over the pulleys and then closing of the housing. Belt tensioning means is preferably or necessarily provided. In accordance with a preferred embodiment of the invention the bell housing is made circular and eccentric of the impeller shaft centre, the bell housing mating with a co-acting circular : formation in the connecting housing. This allows the belt to be tensioned after placement on the pulleys by mating the bell housing to the connecting housing and rotating the one relative to the other to apply tension to the belt.

In this embodiment the preload bearing may simultaneously serve as the bearing that takes up the load imposed by belt tension.

In accordance with a preferred embodiment of the invention the housing for the impeller shaft and associated components includes a bell-housing structure extending integrally to a tube-like structure, having a stepped bore of x. 20077076 34 diameters that decrease from proximal towards distal end and allows insertion of the impeller shaft from the bell housing end. The proximal end is closed by means of an end plate through which the shaft projects to carry the impeller.

The impeller is preferably made of a polyurethane or polymer of similar properties that is moulded onto a boss which in turn is mounted on the shaft by a wedge lock means. The bell housing allows sealed connection to the motor directly or through the connecting housing, so that the whole mixer is sealed.

THE DRAWINGS

The invention is more fully described by way of example with reference to the drawings, in which : -

Figure 1 is an axial cross sectional partial elevation of a mixer according to one embodiment of the invention,

Figure 2 is an axial cross sectional elevation of part of a mixer according to another embodiment of the invention,

Figure 3 is an elevation in axial direction of the mixer part shown in figure 2,

Figure 4 is a side elevation of the mixer partly shown in figure 2,

Figure 5 is an elevation n axial direction of the mixer shown in figure 4.

THE PREFERRED EMBODIMENTS

As shown in figures 1 to 3, the mixer design is such that the Back Thrust (BTH) generated by the propeller 19 Mixing Force (MF) is taken up by means of a Taper Roller Bearing 5 which is fitted onto an Output Shaft 10 positioned inside the Output Housing 13 facing the direction of the Back Thrust.

The Tape Roller Bearing 5 which is fitted on to Output Shaft 10 inside the

Output Housing 13 is installed with a Double Angular Contact Bearing 6 also fitted to the same Output Shaft 10 inside the Output Housing 13.

The purpose of the Double Contact Bearing 6 is to accommodate the Axial (Ax) and Radial (Ra) load generated by the rotation of the Propeller 19.

Pre loading of the Double Contact Bearing 6 and the Taper Roller Bearing 5 is done by setting the Pre load tension with a Lock Nut 9 which is tightened towards the Angular Contact Bearing by means of a special C spanner until correct tension is achieved. Lock Nut 9 which is tightened on Out Put Shaft

Pre Load Angular Contact Bearing 6 whose outer race shoulder bottoms out on a shoulder inside Output Housing 13 with Taper Bearing 5 whose Taper

Cup bottoms out against a shoulder inside Output Housing 13. This has the result that the Double Angular Contact Bearing 6 and the Taper roller Bearing are pre loaded towards one another.

Once correct tension is achieved Lock Nut 9 is locked in position by Lock

Washer 8 located between Lock Nut 9 and the Nylon Ring 7; the Lock Nut 9 prevents working loose and loss of Pre Load Tension between the Double

Angular Contact Bearing 6 and the Taper Roller Bearing 5.

The Lock Washer is in its turn locked by means of a section locating inside the keyway 32 on the Out Put Shaft this stops it from turning with the Lock Nut 9.

Lubrication of the Double Angular Contact Bearing 6 and Taper Roller Bearing 5 is provided by Grease pre packed in cavity 12 filled with grease.

Grease lubricating the Bearings inside the Out Put Housing 13 is kept in place by means of a Nylon Ring 7 on the Double Angular Contact Bearing side and an Oil Seal 4 on the Taper Roller Bearing side.

The Out Put Shaft 10 inside the Output Housing 13 is kept Dry, i.e. stopping water from entering, by means of a Mechanical Shaft Seal 2.

The Mechanical Shaft Seal 2 is a combination of components namely

Stationary Seat, Rotating Seat, Tension Spring.

The operation of the Mechanical Shaft Seal 2 is by means of the Rotating

Seal face Sealing against the Stationary Seal face. The Rotating Seal face also seals on the Out Put Shaft 10 by means of a rubber boot. The Stationary

Seal face is held in a cup rubber which is situated in the Stationary Seat Seal

Housing 15. The Mechanical Shaft Seal faces 2 are tensioned by the

Mechanical Shaft Seal Spring 2. The Stationary Seat Seal Housing 15 closes off the Mechanical Shaft Seal inside the Out Put Housing 13; this has the important result that the Mechanical Shaft Seal 2 is kept out of contact with the Product that is external to the mixer, for example sewerage, which can have items such as cloth that disrupts seals that are located outside the mixer.

The cavity 3 inside the Out Put Housing 13 which houses the mechanical

Shaft Seal 2 is filled with oil in order to lubricate and cool the Mechanical

Shaft Seal 2.

Having the Mechanical Shaft Seal, 2 lubricated and out of the Product allows for Dry Running.

Having the Mechanical Shaft Seal 2 out of the product extends the service cycle of the Belt Driven and Direct coupled Submersible Mixer as no stringy or abrasive materials get in direct contact with the Mechanical Shaft Seal.

This can happen as oil is used for lubrication and cooling instead of using the

Product in which the seal is located in designs where the seal is outside the mixer housing.

A Primary Seal 1 is used to act as a screen and to close off the cavity surrounding the Out Put Shaft 10 and the Stationary Seal Seat Housing 15.

The Primary Seal 1 seals on the rotating Out Put Shaft 10. “O” Rings 14 prevent water seeping through the joints, providing sealing of spigots and flanged faces.

Propeller 19 is a two-blade self cleaning one of different diameter fitted to the

Out Put Shaft 10 and is held on by a Locking Element 17 to the Out Put Shaft 10.

Inside the propeller 19 is a Drive Element 16 which is moulded in when manufacturing of the Propeller take place.

The Locking Element 17 is closed off by means of a Cover 18 which bolts on to the Out Put Shaft 10 Flange and “O” Rings 14 provide spigot sealing.

The Out Put Shaft Housing is bolted to a Transfer Casing 23 which houses the Drive Pulleys 24 and the Tooth Belt 25.

On them, other end the Submersible Motor 26 is bolted to the Transfer Casing 23 is a Tooth Pulley 24 which is connected to the Rotor Shaft of the

Submersible Motor 26. :

Driving the Output Shaft 10 inside the Out Put Housing 13 takes place via

Toothed Pulleys 24 and a Toothed Belt 25. Different output speeds are achieved by altering ratios inside the Transfer Casing. This results in different centre distances. To accommodate the different ratios and to tension the different Drive Belts 25 inside the Transfer Casing 23 the Out Put Housing 13 is Offset 22 to the Output Shaft 10.

The Clamp Ring 20 which locks the Out Put Housing 13 to the Transfer y

Casing 23 is loosened and the Out Put Housing 13 turned until correct tension is achieved. The Offset of the Output Shaft 10 within the Out Put Housing 13 allows for multiple ratios within one design.

Locking the Out Put Housing 13 with the Lock Ring 20 to the Transfer Casing 23 keep the Drive Belt 24 tensioned.

All spigots and flanges are equipped with “O” Rings 14 allowing water tight sealing of spigots and flanges.

The submersible Motor 26 used is the Fluid VX type which has its own unique features. The large Angular Contact Bearing 25 in Removable Bearing

Housing 28.

Bearing Cover 27 assures a sturdy bearing assembly.

Multiple kW and Speed with in one design combined with multiple ratio options allow for wide range of Belt Driven and Direct Coupled Submersible

Mixers.

In the case of a Non Reduction Submersible Mixer, no Toothed Belt or

Toothed Pulleys are used. The output Housing 13 with the combined transfer casing bolts straight on to Submersible Motor Housing flange 31. The Out Put

Shaft 10 is direct coupled to the Submersible Motor Rotor Shaft 24 by means of a keyed hollow shaft. Submersible Motor Rotor shaft 24 is locked with a

Grub screw 30 on the key situated on Out Put Shaft 10.

Speed reduction is by changing Poles on the Submersible Electric Motor 26.

Advantage Features of Submersible Tooth Belt and Direct Coupled

Mixers: }

By accommodating the BTH — Back Thrust generated by the Propellers MF —

Mixing Force by means of the Output Shaft configuration described, allows for longer service time and less downtime. Submersible Mixers currently in use do not allow for BTH — Back Thrust generated by the MF — Mixing Force of the Propeller, resulting in Mechanical Seal and bearing failure. Collapsed

Bearings miss align reduction gears with devastating results. Having a preset load on the Output Shaft that stabilizes the movement on the Mechanical

Shaft Seal results in a dry Output Assembly and a longer bearing life. Having the Mechanical Shaft Seal out of the Product and Lubricated by means of oil instead of relying on Product for cooling and lubrication allow for Dry-Running and prevent String materials to enter the Mechanical Shaft Seal spring, which reduces tension and allows water to enter. Failure and down time are the result. Downtime in the water purification process means that breaks in agitation result in media settlement and this influences the results. Making use of Toothed Pulleys and a Toothed Belt allows for dry reduction inside the

Transfer Casing, instead where oil is used in Geared reduction mixers. Oil lubricated reduces system leaks into the electric motor which would result in motor winding failure.

Having an Offset out Put assembly allows for Multi Speed Reductions all with in one standard design, making parts more available and cost effective.

Having no reduction in the case of Direct Coupled Submersible Mixer, allows for reduced weight and stream line design. Disadvantages are that set out put speeds are determined by Electric Motor Poles but can be varied with : frequency-controlled device. This is costly and requires skilled personnel to maintain.

In both Submersible Mixers Oil Free Transfer Casings are used creating a safe environment as oil spillage is ruled out. -=meeemee=-000----

Claims

SE x. 2007/7076 34 , RY 11111 . —

1. A mixer which is characterised by a thrust bearing located on the impeller shaft, is preloaded by a co-acting bearing and has the thrust bearing located at a proximal position of the shaft and the preload bearing at a distal position on the shaft, with means for applying a preload provided on the shaft adjacent the preload bearing.

2. A mixer which is characterised by a thrust bearing located on the impeller shaft, is preloaded by a co-acting bearing and has the thrust bearing located at a distal position of the shaft and the preload bearing at a proximal position on the shaft, with means for applying a preload provided on a housing in which the bearings are housed, adjacent the preload bearing.

3. A mixer as claimed in either one of claims 1 or 2, in which the mixer has sealing means against ingress of liquid located inside the housing of the mixer.

4. A mixer as claimed in claim 3, in which the sealing means comprises a primary seal and a secondary seal, the latter consisting : of a spring activated seal.

5. A mixer as claimed in any one of claims 1 to 4, in which the means for applying a preload is a screw threaded appliance.

6. A mixer as claimed in any one of claims 1 to 5, in which the impeller shaft is connected to the motor by a reduction connection that comprises a toothed belt drive, the drive constituted by a pulley on the impellér shaft and a pulley on the motor shaft with a connecting housing that allows threading the belt over the pulleys and then closing of the housing.

7. A mixer as claimed in claim 6, in which belt tensioning means is provided by means of the bell housing being made circular and eccentric of the impeller shaft centre, the bell housing mating with a co-acting circular formation in the connecting housing.

8. A mixer as claimed in any one of claims 1 to 8, in which the housing for the impeller shaft and associated components includes a bell- housing structure extending integrally to a tube-like structure that has a stepped bore of diameters that decrease from proximal towards distal end and allows insertion of the impeller shaft from opposite the bell housing end, the proximal end closed by means of an end plate through which the shaft projects to carry the impeller.

9. A mixer as claimed in any one of claims 1 to 8, in which the impeller is made of a polyurethane or polymer of similar properties that is moulded onto a boss which in turn is mounted on the shaft by a wedge lock means.

10. A mixer as claimed in any one of claims 1 to 9, in which the bell housing allows sealed connection to the motor directly or through a connecting housing, so that the whole mixer is sealed.

11. A mixer as herein described and as illustrated in figure 1 of the drawings.

12. A mixer as herein described and as illustrated in figures 2 and 3 of the drawings. -=-mmememea=--000------------ HAHN & HAH APPLICANTS He