GB2110955A - Waste pulping apparatus - Google Patents

Abstract

An apparatus for the pulping of waste material is disclosed including a tank, 80 and impeller, 72 a slurry chamber, 88 and a discharge pipe 104 for removal of slurry from the chamber. The impeller is positioned horizontally at the bottom of the tank and is positioned off-center so waste material, when added to the tank will not directly impinge upon the blades or cutting surfaces of the impeller. <IMAGE>

Description

SPECIFICATION Waste pulping apparatus The field of the invention relates to waste pulping equipment for waste treatment and disposal.

In equipment of this type, waste materials are introduced into an impeller-created vortex of water, reduced to a pulp, and passed onto a water extraction device with the excess water separated and returned to the pulper for reuse. Such waste pulping machines are often provided with blades or cutting members mounted to the impeller to provide a shearing action as the impeller rotates. The blades also enable the pulping equipment to handle a quantity of non-pulpable material, such as plastic, which generally constitutes a minor portion of the waste to be disposed.

When introducing waste material into the tank of a pulping machine, such potentially damaging material as silverware or bottle caps could damage the impeller. Horizontally disposed impellers are inherently subject to such damage. Vertically disposed impellers are not, but vibration problems have limited their utility. This is due to cavitation, ie, the formation of air pockets in the slurry chamber.

Providing a water level which is higher than the level of the impeller has been suggested as a solution in US Patent Application, Serial No 714,609 filed August 16, 1976, but efficiency of the apparatus is reduced to an extent. Another problem with this method is that floatables such as styrofoam will not be pulped due to their flotation above the impeller.

The invention is directed to a pulping system which combines high efficiency with little possible damage to the impeller. It also minimizes the effects of possible vibrations within the pulping tank.

In accordance with these objectives together with the desire to produce an economical and reliable apparatus the present invention provides an apparatus for pulping waste comprising: a pulping tank having substantially symmetrical side walls and adapted for holding a quantity of water and waste material; an upper opening towards the top of the tank for allowing the introduction of waste material therein and a bottom opening in the bottom of the tank; an impeller mounted across the bottom opening of the tank for reducing water and waste material to a slurry, the rotational axis of the impeller being positioned off-centre relative to the axis of the tank for creating a relatively large bottom area on one side of the tank upon which waste material may be introduced to the tank without directly impinging upon the impeller, thereby permitting the introduction of objects in the waste material that should be free from action of the impeller; and a substantially cylindrical slurry chamber is positioned beneath said impeller, said tank being mounted eccentrically with respect to said slurry chamber. the slurry chamber being separated from the tank by said impeller, which extends into the slurry chamber, and a sieve, the sieve allowing water and waste material reduced to a slurry by said impeller to enter the slurry chamber.

To minimize or even eliminate potential damage to the impeller due to the introduction of silverware or other material to the tank; the impeller is located off-center relative to the axis of the tank which is preferably substantially cylindrical. A relatively large area for introducing waste is accordingly provided on one side of the tank where potentially damaging materials may be trapped before they can reach the impeller. Ashield may be provided to protect the impeller from waste material introduced from the top of the tank and to provide an opening where waste can be safely introduced.

A waste pulping apparatus constructed in accordance with the present invention will now be described by way of example only, with reference to the accompanying drawings in which: Figure lisa side elevation view of a waste pulping apparatus having a horizontally disposed, off-center impeller; and Figure 2 is a top view of the apparatus shown in Figure 1.

Referring to the accompanying drawings, a waste pulping assembly 70 is provided having a horizontally disposed impeller 72. Since vibration does not present as much of a problem in such pulpers (as opposed to those having vertically disposed impellers) mechanical isolators or other shock absorbing means are not necessarily utilized.

The assembly 70 is mounted on a frame 74 having legs 76 with rubber feet 78. A cylindrical pulping tank 80 is provided having a side wall 82, a bottom 84, and a top opening 86. A cylindrical slurry chamber 88 is positioned beneath the bottom of the tank and a motor 90 for driving the impeller is shown beneath the slurry chamber. The impeller 72 shown in Figure 5 together with a sieve (not shown) separates the tank from the slurry chamber. A similar arrangement is disclosed, for example, in US Patent No.3,885,745.

It is readily apparent from the drawings that the impeller shaft 92 about which the impeller 72 rotates is significantly off center from the vertical axis for symmetry of the cylindrical tank 80. This provides a relatively large area 94 on the opposite side of the impeller upon which waste material can be introduced without directly impinging upon the impeller.

This is important as objects such as silverware or salt shakers mixed with the waste can damage the impeller if they contact it. By introducing them over area 94 where they may sink to the bottom of the tank and be trapped within shields 96,98, damage to the impeller may be substantially avoided.

To further facilitate the introduction of waste material into the tank 80, the tank is rotatable about an axis defined by the center of the impeller 72.

When the eight bolts 100 securing it to the slurry chamber 88 are loosened sufficiently or removed, the tank may be rotated eccentrically with respect to the chamber as shown in phantom in Figure 5.

Waste may then be introduced where it is most convenient for the operator.

Owing to the rotational movement of the impeller, a vortex is created which draws the waste material and water to the impeller so that a slurry is produced. Baffles 102 may be provided to control the flow. When the waste material is of sufficiently small size, it is able to pass through the sieve into the slurry chamber. The slurry within the slurry chamber also rotates owing to the action of the impeller.

A slurry pipe 104 is connected to the slurry chamber. The pipe 104 allows slurry to flow horizontally, then vertically upwards, horizontally again, and then downwardly to the base of an extractor 106.

The extractor may be similar to one described in US Patent Application Serial No 911,783 filed June 2, 1978. An air relief hose 108 is connected between the slurry pipe and the tank 80.

Water which has been separated from the solid portion of the waste is returned to the tank by a return pipe 110. A return pump 112 is provided near the bottom of the extractor for pumping the extracted water through the pipe 110. To prevent the water level within the extractor from being too high, an overflow pipe 114 is connected thereto. The overflow pipe is connected to the slurry pipe via valve 115. A water controi assembly 116 is also provided to maintain the height of the water in the tank.

The same motor 118 is utiiized for driving both the shaft 120 of the extractor and the return pump 112. A first belt 121 is connected between the first flywheel and a second flywheel 124 so that they will rotate in unison. A second belt 126 extends between the second flywheel and a third flywheel 128 operatively connected to the shaft 120 of the extractor. The pump 112 is also operatively connected to the motor via flexible shaft coupling 130.

In operation, the waste material is reduced to a slurry in the pulping tank from where it passes through the sieve into the slurry chamber. The slurry flows through the slurry pipe 104 to an extractor 106.

The liquid portion of the slurry is returned from the extractor to the tank via a return pump 112 and pipe 110. The solid portion of the waste exits the top of the extractor through a discharge chute 132 with a hinged cover 134.

Claims (6)

1. An apparatus for pulping waste comprising: a pulping tank having substantially symmetrical side walls and adapted for holding a quantity of water and waste material; an upper opening towards the top of the tank for allowing the introduction of waste material therein and a bottom opening in the bottom of the tank; an impeller mounted across the bottom opening of the tank for reducing water and waste material to a slurry, the rotational axis of the impeller being positioned off-center relative to the axis of the tank for creating a relatively large bottom area on one side of the tank upon which waste material may be introduced to the tank without directly impinging upon the impeller, thereby permitting the introduction of objects in the waste material that should be free from action of the impeller; and a substantially cylindrical slurry chamber is positioned beneath said impeller, said tank being mounted eccentrically with respect to said slurry chamber, the slurry chamber being separated from the tank by said impeller, which extends into the slurry chamber, and a sieve, the sieve allowing water and waste material reduced to a slurry by said impeller to enter the slurry chamber.

2. An apparatus as claimed in claim 1 or claim 2, wherein said side walls define the opening at the top of the tank.

3. An apparatus as claimed in claim 1 or claim 2, wherein a shield is provided near the top of the tank for preventing waste material from directly impinging upon the impeller.

4. An apparatus as described in any one of claims 1 to 3, wherein a shield is provided at the bottom of the tank for restricting the movement of non-pulpable material such as silverware towards the impeller.

5. An apparatus as claimed in any one of claims 1 to 4 wherein said pulping tank is substantially cylindrical.

6. An apparatus as claimed in any one of Claims 1 to 5, wherein said pulping tank is rotatably adjustable about the axis of said slurry chamber.

6. An apparatus as claimed in any one of claims 1 to 5, wherein said pulping tank is rotatable with respect to said slurry chamber.

New claims or amendments to claims filed on 4 February 1983 Superseded claims 1,6

1. An apparatus for pulping waste comprising: a pulping tank having a side wall with an axis of rotational symmetry and adapted for holding a quantity of water and waste material; an upper opening towards the top of the tank for allowing the introduction of waste material therein and a bottom opening in the bottom of the tank; an impeller mounted across the bottom opening of the tank for reducing water and waste material to a slurry, the rotational axis of the impeller being parallel to said axis of symmetry of the tank wall to create a relatively large bottom area on one side of the tank upon which waste material may be introduced to the tank without directly impinging upon the impeller, thereby permitting the introduction of objects in the waste material that should be free from action of the impeller; a substantially cylindrical slurry chamber positioned beneath said impeller, the axis of the slurry chamber being coaxial with the said axis of rotation of the impeller, the slurry chamber being separated from the tank by said impeller, which extends into the slurry chamber; and a sieve, the sieve allowing waste and waste material reduced to a slurry by said impeller to enter the slurry chamber.