Field of Invention

The invention relates to a device and method for separating material from liquids such as, but not limited to, the separation of oil and/or fat from water.

Background

When fruits nuts and vegetables are processed to extract their oils and fats, there is inevitably some loss of oil and fat to the wastewater generated during the procedure.

For instance, it is generally accepted within the industry of oil palm fruit processing that, in the two types of hot waste water generated (typically around 80 degrees Celsius) during extraction, cooking and processing, losses to centrifuge and/or decanter waste water (referred to as 'sludge') are typically about 0.8% of Crude Palm Oil (CPO). Condensate waste water from the oil palm fruit sterilisation and cooking process also contains typically about 0.8% CPO. Other types of fruit, nut, or vegetable oils have similar loses to water, liquid or waste water. Conventionally, the two waste water streams from the stages of pressure cooking/sterilisation and centrifugal extraction in oil palm fruit processing are combined and sent to a very large area in a ground oil trap (referred to as a cooling pond). Here attempts are made to retain the small yet economically and environmentally significant percentage of crude palm oil.

However, due to the length of time spent in the oil trap, the trapped crude palm oil becomes of a commercially unacceptable quality, and leads to a disposal problem as well as a significant loss of revenue for the oil owner. Moreover, a quantity of the oil is not trapped and finds its way out of the numerous anaerobic and aerobic in-ground ponds that are currently used to treat the waste water.

The anaerobic and aerobic in-ground ponds take up vast areas of land that could be better utilised, for example to cultivate oil palm. The earth ponds also pose a risk of seepage of waste water contaminants into local water course, streams, rivers and subterranean water deposits, thus causing harmful contamination. In addition, bad odours are produced during the anaerobic/aerobic process that affect surrounding areas with noxious smells.

There is thus a need in the industry for a better way of dealing with such waste water that allows recovery of as much as possible of the valuable oils and fats, requires a smaller land area for implementation, and minimizes the risk of serious contamination of the surrounding environment.

Summary of Invention

In an aspect of the invention, there is provided a separation device comprising:

a series of separation chambers successively connected to allow the flow of liquid therethrough;

one or more of the separation chambers arranged such that the liquid can flow therethrough in a substantially downward direction;

a further one or more or the preceding and/or succeeding separation chambers arranged such that the liquid can flow therethrough in a substantially upward direction; characterised in that oils and/or fats in the liquid float upwards and collect in at least one collection chamber.

In one embodiment the separation chambers are arranged such that the flow of liquid therethrough alternates between substantially upward and downward directions.

Thus as the liquid flows through the chambers of the device, the oil and/or fat droplets therein coalesce and rise to the surface of the liquid, forming an oil/fat layer in the collection chamber. It will be appreciated that the invention is not limited to recovery of any particular natural oils or fats, although it was developed in particular consideration of problems associated with CPO production, an example of edible oil. In one embodiment the separation device includes a first separation chamber, through which the liquid flows in a substantially downward direction into a second separation chamber, through which the liquid flows in a substantially upward direction into a third separation chamber, through which the liquid flows in a substantially downward direction.

In one embodiment the flow rate of the liquid is less than the rise rate of oils and/or fats in the liquid. This allows the oils and/or fats to rise against the flow of the liquid where applicable. In one embodiment the flow rate of the liquid is up to around 20 litres per minute, typically from around 1.1 litres per minute to around 17.2 litres per minute

It will be appreciated that as droplets of oils/fats coalesce together to form larger more buoyant droplets, the flow rate can be adjusted to ensure that a minimum size of droplet rise to the surface. Typically the slower the flow rate of the liquid, the smaller the oil/fat droplets that will rise against the downwards flow of the liquid, and therefore the more oil/fat can be recovered (although the slower the process will be). In one embodiment the separation device includes a substantially cylindrical housing. Typically the separation chambers are divided by baffle plates.

In one embodiment the separation device includes an inlet in the first of the successively connected separation chambers, and an outlet in the last of the successively connected separation chambers. Typically waste water enters through the inlet and exits through the outlet.

In one embodiment the inlet and/or outlet includes a substantially vertical riser pipe.

In one embodiment a perforated baffle plate is attached to the end of the inlet riser pipe, typically by one or more supporting rods.

The perforated baffle plate helps smaller oil droplets to coalesce together, and stops disturbances at the oil water interface above the baffle plate thereby preventing possible remixing of the oil and water in this zone.

In one embodiment a controller is provided to adjust the level of liquid in the separation device. Typically the controller is located in or near the outlet.

In one embodiment the collection chamber is common to two or more of the separation chambers. Typically the collection chamber extends across the top of two or more of the separation chambers. In a further embodiment a plurality of collection chambers are provided, typically positioned at or near the top of the respective separation chambers. Typically one or more of the collection chambers are separated by baffle plates.

In one embodiment the collection chamber is provided with one or more openings to allow the flow of oils and/or fats therefrom. Typically the oils and/or fats are discharged through the openings when they reach a sufficient level in the collection chamber. In one embodiment each opening is provided with a weir, which is typically serrated. This helps to control and/or measure the rate of oils and/or fats discharged from the collection chamber.

In one embodiment the separation device includes a solids chamber arranged between two of the separation chambers, for collecting solids material as the liquid flows therethrough.

Typically the solids chamber is arranged between the first separation chamber through which liquid flows in a substantially downwards direction, and the subsequent separation chamber through which liquid flows in a substantially upwards direction. Thus as the flow of liquid changes from a substantially downwards direction to a substantially upwards direction as it passes through the solids chamber, solid waste material falls towards the bottom thereof. In one embodiment the solids chamber is provided with a solids outlet. Typically the solids outlet is located at the bottom of the solids chamber.

In a further aspect of the invention, there is provided a method of separating oils and/or fats from a liquid, comprising the steps of:

flowing the liquid through a series of successively connected separation chambers in a separation device;

the direction of the liquid flow being alternated between a substantially downward direction and a substantially upward direction;

characterised by collecting coalesced oils and/or fats in at least one collection chamber at the upper end of the separation device.

In one embodiment the flow rate of the liquid is controlled such that oil and/or fat droplets can float upwards to the collection chamber. In one the collected oils and/or fats are discharged through an outlet when they reach a predetermined level. In one embodiment solids are collected in a solids chamber, and may be discharged through a solids outlet at the discretion of the user.

Brief Description of Drawings

It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible, and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.

Figure 1 is a schematic sectional side view of a separation device according to an embodiment of the invention.

Figure 2 is a schematic sectional isometric view of (a) a separation device according to an embodiment of the invention; (b) a closeup sectional view of the collection chamber; and (c) a closeup sectional view of the outlet from the collection chamber.

Detailed Description

With reference to Figures 1 -2c, there is provided schematic views of a separation device wherein waste water containing oils and/or fats enters the primary separation chamber 6 via waste water inlet 1 and flows through the vertically rising inlet pipe 2 therein. The primary separation chamber 6 has a cylindrical outside wall 26 and internal baffle plate 9 which separates the primary separation chamber from the secondary separation chamber 12.

A perforated baffle plate 5 is attached to the outlet 3 of the vertical inlet riser pipe 2 by one or more supporting rods 4 to provide an annulus area for the waste water to enter the primary separation chamber 6 where the flow moves slowly in a downward direction as indicated by arrow 23, to get past the internal baffle plate 9.

As the flow moves downwards, the larger droplets of oils and fats coalesce together to form larger more buoyant droplets which rise vertically as indicated by arrow 24 through the waste water to form a concentrated free layer 10 on top of the waste water in the collection chamber 25.

The waste water exits the primary separation chamber 6 and into solids separation chamber 7 where any solids material within the waste water is allowed to separate and be collected at the bottom of solids collection chamber 7 where it can be discharged through solids outlet 8.

The waste water, now containing reduced amounts of oils and/or fats, flows through chamber 7 to secondary separation chamber 12 which is formed by baffle plate 9 and the final separation chamber wall 27 and the closed off bottom 28 and outside wall 26 of the device. The waste water flows in a vertical direction as indicated by arrow 29 through the secondary separation chamber 12, and during this process the fine oils and/or fats droplets coalesce together to form larger droplets which float upwards as indicated by arrow 30 to form free layer 10' in the collection chamber 25', separated from free layer 10 and collection chamber 25 by the extension of baffle 9.

The waste water, now containing lesser amounts of oils and/or fats, flows to the final separation chamber 18 where the waste water flows towards the bottom outlet 19. During this process further separation of the coalesced oils and/or fats takes place with the larger oils and fats droplets moving in an upwards direction, as indicated by arrow 32, against the downward flow 31 of the waste water. On reaching the top of separation chamber 18, the droplets join with other previously separated oils and/or fats 10' in the collection chamber 25'.

As the volume of oils and/or fats increases in the collection chambers 25', 25 they eventually flow through respective openings 1 1, 13 in the outside wall 26 via serrated overflow weirs 14, 15 to an outlet chamber 16 and subsequent outlet 17. Meanwhile the waste water flows through final separation chamber, as indicated by arrow 31, to the waste water outlet 19, and passes into a vertical waste water outlet pipe 20 where it flows vertically to the adjustable level controller 21 before flowing out through final waste water outlet 22. It will be appreciated by persons skilled in the art that the present invention may also include further additional modifications made to the device which does not affect the overall functioning of the device.