GB2349101A - An animal slurry pump feeds slurry to a venturi to which air is drawn or supplied - Google Patents

Abstract

A pump for use in an animal slurry tank comprises an impeller 2 which pumps slurry from an inlet 13 through a conduit 6 with an air line 11 which discharges air in the direction of the flow of slurry along the conduit thereby mixing and agitating the slurry. The air line 11 can be attached to an external air pump if the vacuum effect provided by the pressurised jet of slurry is unable to supply enough air. The air line can be connected to a chemical/enzyme reservoir so that the pressurised jet of slurry can draw in chemicals or enzymes at a regulated rate.

Description

A SLURRY PUMP The present invention relates to a slurry pump and in particular to a slurry pump for use in a slurry tank.

Most slurry pumps are tractor powered although they can also be electrically powered.

The basic way a slurry pump works is that the pump is lowered into a slurry tank, which is usually between 1. 5m and 4.5m deep. A powered impeller at the bottom of the pump lifts the slurry, which is then jetted out through the unmixed slurry from an outlet at high pressure. To create a good mix the outlet can be moved up or down and from left to right.

When mixing, the jet of slurry"Punches"a hole through the unmixed slurry and through time causes the whole tank to circulate and mix.

The slurry pump is used for mixing slurry which has been collected over a period of time, generally the winter months when animals are housed. Slurry collected in a tank or pit needs to be mixed to a uniform viscosity so that it can be easily transferred to other tanks or made ready for disposal on the field. Generally tanks are only mixed using this type of pump immediately prior to the transfer or removal of slurry from the tank.

The average size of tractor over the last five years has grown considerably. Therefore the implements these larger tractors can drive have increased in capacity accordingly. Most slurry pumps on the market require a horsepower of approximately 85 horsepower (63. 41 KWatts) to drive which is below the average horsepower (kW) available on farms today.

The outlet pressure would have a relationship with the power available to drive it, in that the more power available, the more pressure at the outlet. If a slurry pit is an awkward shape, has limited access or slurry is very thick, mixing can be very difficult and a time consuming job.

There are also recognised serious safety problems when mixing slurry, as odorless lethal toxic and flammable gases are given off when mixing. This has caused numerous fatalities in the farming industry. The object of the present invention is to overcome the difficulties associated with the prior art.

Accordingly, there is provided a slurry pump comprising means for pumping slurry, an associated conduit having an opening for slurry adjacent the pumping means and at least one outlet for slurry, with an air supply means provided along the conduit, whereby in use the air supply means discharges air in the direction of the flow of slurry along the conduit thereby improving the rate of mixing and agitating of the slurry.

This improved mixing system will greatly reduce the length of time an operator needs to spend in a building supervising the mix and also in time moving the pump to other locations within the building to achieve a satisfactory mix.

Advantageously, the slurry pumping means is provided by an impeller.

Beneficially, the conduit comprises a mixing nozzle at the slurry outlet for discharging the pumped slurry in a pressurised jet into the surrounding unmixed slurry.

Advantageously, the mixing nozzle may be formed from a combination of converging/diverging ducts. The converging/diverging ducts may be modified to provide optimum mixing conditions.

The air supply means includes an air line and a vacuum created by the pressurised jet of the pumped slurry. The suction force created by the pressurised jet passing through the mixing nozzle will draw air down the air line creating greater turbulence and a better mixing ability.

Advantageously the air line is detachably mountable to a chemical/enzyme reservoir whereby the vacuum created by the pressurised jet of slurry draws the chemical/enzyme down the air line. The slurry pump could be used to add chemicals or enzymes at a regulated rate. If these substances were added at the pressure nozzle it would mix the enzymes well into the slurry and result in a reduced operation for adding the slurry additive and a more consistent mix through the slurry pit.

In a preferred embodiment the conduit includes a second outlet for delivering slurry to a remote container.

The air supply means may also include a detachable external air pump.

In a particularly preferred embodiment the air supply is provided by an air line internally located in the mixing nozzle. The air is added at the pressurised outlet of the pump to achieve greater turbulence and therefore a faster mix.

In a further embodiment the air is supplied by a number of air lines located on the outside of the mixing nozzle.

In a still further embodiment the air is supplied at both the mixing outlet and along the conduit. This would allow greater volumes of air to be added if necessary and there would be the facility to operate the pump without this air assistance if necessary.

The invention will hereinafter be more particularly described with reference to the accompanying drawings, which show by way of example only, a number of embodiments of the slurry pump according to the invention.

In the drawings: Figure 1 is a side view of a slurry pump in accordance with the invention ; Figure 2 is a front view of the slurry pump of Figure 1 ; Figure 3 is a side view of the mixing nozzle of Figures 1 and 2 in accordance with the invention; Figure 4 is a front view of the mixing nozzle of Figures 1 to 3; Figure 5 is a side view of a second embodiment of a slurry pump in accordance with the invention; Figure 6 is a front view of the slurry pump in Figure 5; Figure 7 is a side view of the mixing nozzle of Figures 5 and 6 in accordance with the invention; and Figure 8 is a front view of the mixing nozzle of Figures 5 to 7.

Referring to the drawings and initially to Figures 1 and 2 there is illustrated a slurry pump 1 in accordance with the invention. The slurry pump 1 is provided with a pumping means in the form of an impeller 2 that is operated by a motor (not shown) through a gearbox 3 which can change the ratio of drive from the motor and the direction of drive through ninety degrees. The gearbox 3 drives the impeller 2 through a drive shaft 4. A conduit 5 is situated above the impeller 2 presenting an opening 31 adjacent the impeller 2. The conduit 5 branches at a point 32 above the impeller 2 and provides an outlet pipe 6 terminating in a mixing nozzle 7. A second filling pipe 8 extends above the floor of the slurry tank (not shown) terminating in a gate valve 9 and coupling 10. An air supply is provided by a detachable external air pump (not shown) and an air line 11 attached along the nozzle handle 12. The air line 11 enters the mixing nozzle 7 and rests in a predetermined position.

Referring now to Figures 3 and 4, there is illustrated a mixing nozzle 7 in accordance with the invention. The outlet of the mixing nozzle 7 is formed as a venturi tube comprising a converging duct 41, a cylindrical duct 42 and a diverging duct 43. The mixing nozzle 7 is attached to a rotatable drum 13 which is mounted on a nozzle box 14. The nozzle box 14 is mounted on one end of the outlet pipe 6 and is supported by a strut 15 (see figure 2). The rotatable drum 13 has a inlet 16, that can be varied in size in correlation with the angle of rotation of the drum 13, to deliver the slurry to the mixing nozzle 7. An air line 11 enters the mixing nozzle 7 adjacent the drum 13 through a bushing 17 and rests in a predetermined position.

Referring to the drawings and in particular to Figures 5 and 6, there is shown a second embodiment of a slurry pump in accordance with the invention, in which parts similar to those identified with reference to Figures 1 to 4 are identified by the same reference numerals generally. In this embodiment the air supply is again provided by a detachable external air pump (not shown) and an air line 11 attached to the nozzle handle 12. The air line 11 does not enter the mixing nozzle 7 but provides air to an air ring 18 which circles the mixing nozzle 7 at the joint between the nozzle 7 and the rotatable drum 13. The air ring 18 provides air to further air lines 19 which extend from the air ring 18 to the outlet 20 of the mixing nozzle 7.

Referring now to Figures 7 and 8, there is illustrated a mixing nozzle 7 in which the air line 1. 1 is attached to the air ring 18 by a spigot 21. The air lines 19 extend from the air ring 18 along the outside wall of the mixing nozzle 7 to provide an air supply around the outlet 20.

The air lines 19 are equi-spaced around the circumference of the outlet 20 to provide an even air distribution.

In use, the slurry pump 1 is lowered into a slurry tank (not shown) and the impeller 2 is powered by either a tractor or electric motor. The slurry is raised by the action of the impeller 2 and forced into the nozzle 7, producing a high pressure jet of slurry that punches a hole in the surrounding unmixed slurry. The suction force created by the pressurised jet passing through the mixing nozzle will draw air down the air line creating greater turbulence and a better mixing ability. It will make the air assistance work much more effectively, as it will have the effect of creating a bigger vacuum and therefore draw more air to the slurry, which will create more turbulence. The greater output pressure and flow will enable larger tanks to be mixed from a single mixing position. The addition of air will cause significantly more turbulence and therefore reduce the required mixing time significantly. Furthermore, if the vacuum effect provided by the pressurised jet of slurry is unable to supply enough air, then the external pump can be attached to the air line 11 to provide additional air. Once the tank is fully mixed an outlet adapter (not shown) is connected to the coupling 10 and attached to a suitable container, such as a slurry tanker.

The gate valve 9 is then opened and maximum flow through the filling pipe 8 is achieved by progressively angling the mixing nozzle 7 downwards until the inlet 16 is closed off. In addition to emptying the slurry tank using the slurry pump, a farmer may use other means such as a vacuum pump incorporated into a slurry tanker.

Aerating or oxygenating slurry reduces biological and chemical oxygen demand levels (BOD and COD) and therefore reduce noxious odours, which environmentally makes it more pleasant to dispose of. The addition of air to slurry to date however has been solely to reduce odours rather than to assist with a rapid mixing process. This invention is primarily to aid mixing and any benefits relating to the reduction of BOD and COD levels are secondary.

To reduce biological oxygen demand levels (BOD) which reduces odorous smells, chemicals or enzymes are often added to slurry. Regulations on smell pollution are becoming more rigid and there is legislation in many European countries which restrict farmers spreading slurry at certain times of the year. It is likely that the legislation will also come into force in the U. K. and Ireland some time in the future. The result of this legislation is that more above ground slurry stores will be built and the spreading of slurry in permissible months will be more concentrated. Slurry pumps as well as being used for mixing are used for transferring slurry from one catchment area below buildings to more permanent slurry stores. A suitable point to add the chemicals/enzymes would be when slurry is being moved from a temporary store to a long term store.

It is to be understood that the invention is not limited to specific details described herein which are given by way of example only and that various modifications and alterations are possible without departing from the scope of the invention.

Claims (12)

1. CLAIMS : 1. A slurry pump comprising means for pumping slurry, an associated conduit having an opening for slurry adjacent the pumping means and at least one outlet for slurry, with an air supply means provided along the conduit, whereby in use the air supply means discharges : air in the direction of the flow of slurry along the conduit.
2. 2. A slurry pump as claimed in claim 1, wherein the slurry pumping means is provided by an impeller.
3. 3. A slurry pump as claimed in claim 1 or claim 2, wherein the conduit includes a mixing nozzle at the slurry outlet for discharging the pumped slurry in a pressurised jet into the surrounding unmixed slurry.
4. 4. A slurry pump as claimed in claim 3, wherein the mixing nozzle is formed frorn a combination of converging/diverging ducts.
5. 5. A slurry pump as claimed in any one of the preceding claims wherein the air supply means includes an air line and a vacuum created by the pressurised jet of the pumped slurry.
6. 6. A slurry pump as claimed in claim 5, wherein the air line is detachably mountable to a chemical/enzyme reservoir whereby the vacuum created by the pressurised jet of slurry draws the chemical/enzyme down the air line allowing the slurry pump to add chemicals or enzymes at a regulated rate.
7. 7. A slurry pump as claimed in any one of the preceding claims wherein the conduit includes a second outlet for delivering slurry to a remote container.
8. 8. A slurry pump as claimed in any one of the preceding claims wherein the air supply means also includes a detachable external air pump.
9. 9. A slurry pump as claimed in any one of the preceding claims wherein the air supply is provided by an air line intemally located in the mixing nozzle.
10. 10. A slurry pump as claimed in any one of the preceding claims wherein the air is supplied by a number of air lines located on the outside of the mixing nozzle.
11. 11. A slurry pump as claimed in any one of the preceding claims wherein the air is supplied at both the mixing outlet and along the conduit.
12. 12. A slurry pump substantially as herein described with reference to and as shown in the accompanying drawings.