GB2193219A

GB2193219A - Treatment of oil

Info

Publication number: GB2193219A
Application number: GB08611169A
Authority: GB
Inventors: Denis Bowes Verity
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-05-08
Filing date: 1986-05-08
Publication date: 1988-02-03
Also published as: GB8611169D0

Abstract

A process and apparatus for the treatment of contaminated oils as shown in Fig. 2 can be used for the removal of contaminants such as free fatty acids and particles formed in oils in general, due to degredation during use and in particular during the degradation of cooking oil. The process utilises alkalies coupled with heat for acid separation and Activated Earth coupled with heat to achieve decolouration. Sub micron filtration through a filter arrangement, shown in Fig. 1, is carried out as a final operation to produce the fully treated oil.

Description

SPECIFICATION Treatment of oil This invention relates to a process and apparatus for the treatment of contaminated fluids and more particularly the purification of oil such as cooking oil, lubricating oil, insulating oil, fuel oil and the like.

Cooking oil used for frying will gradually degrade with use due to the formation of free fatty acids and the accumulation of small particles of food. These contaminants have the effect of lowering the smoke and flash points of the oil to an unacceptably low level. Items of food cooked in such contaminated oil are coloured to an unacceptably dark shade. The present practice is to discard such contaminated oil.

The present invention has been made with this problem in mind.

According to the invention there is provided a process for treating contaminated oil comprising contracting the oil with an alkali to neutralise at least a part of the free fatty acid content of the oil, separating the oil phase from the resultant mixture and filtering solid matter from the oil.

Neutralisation of the free fatty acid or part thereof is preferably effected by mixing the alkali and oil together to produce a substantially homogeneous mixture. The mixture is then allowed to separate out into discrete phases. If desired the mixture can be heated to assist separation.. The preferred alkalis are sodium carbonate and sodium hydroxide.

When the oil is a cooking oil the alkali must be non-toxic and preferably an approved food additive.

The separated oil is preferably heated, for example, to 120 C prior to being passed through a filter to remove suspended solid particulate matter. Preferably the filter is one which will remove particles of sub-micron size so that a filtered and polished oil is obtained.

If the oil is discoloured it may also be treated to remove the discolouration, for example, by mixing the oil with Activated Earth, preferably at an elevated temperature, for example, up to 200 C. The mixture is allowed to stand and the solid Activated Earth settles out and can be removed. The decolouring step is preferably carried out after neutralisation of free fatty acid and before filtration of suspended particulate matter.

The invention also comprises apparatus for treating contaminated oil comprising means for separating oil from at least partially neutralised free fatty acids and means for transferring the separated oií to filtration means for removing particulate matter from the oil.

Preferred apparatus for carrying out the process will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is an axial section through a filter housing; and Figure 2 is a schematic flow sheet of a system for treating contaminated oil.

Referring to Fig. 1 the filter housing comprises a cylindrical container 10 preferably of metal, for example aluminium or stainless steel. An inlet port 12 is provided in the centre of the base of the container. The inlet port 12 communicates with a passageway 14 in an axially maligned upstanding boss 16. At the upper end of the boss the passageway 14 divides into a plurality of outlets 18. A threaded bore 20 is provided at the top of the boss 14. The bore 20 receives a bolt 22 by which lid 24 can be removably secured on the container 10. A perforated plate 26 is disposed a short distance above the base of the container. An outlet port 28 is provided in the base about midway between the centre of the base and the edge of the base. In use the housing receives a filter element of annular cross section.The filter element rests on the plate 26 with the boss 14 extending through the aperture in the annular body.

The outlet port preferably has a variable orifice which is adjusted in accordance with the oil being treated and the process condition inter alia, the viscosity of the oil, the pressure in the system and the desired flow rate.

Referring now to Fig. 2 a system for treating contaminated oil comprises an inlet line 30 which is connected through valve 32 to a pump 34. The outlet 36 from the pump is connected to line 38 for delivery via valve 40 to a neutralisation tank 42. The tank 42 is equipped with a thermostatically controlled heater 44, an outlet 46 for lighter phase oil and an outlet 48 for heavier phase waste.

The outlet 46 is connected to line 50 for delivery via valve 52 to a decolouring tank 54.

Tank 54 is equipped with a thermostatically controlled heater 56 and outlet 58 which leads via valve 60 to the input side of the pump 34.

A second line 62 from the output side of the pump leads, via valve 64 to a plurality of parallel connected filters 66 of the kind described with reference to Fig. 1. The outputs 68 from the filters 66 are arranged for delivery of oil to tank 54.

Finally a product output line 70 including valve 72 is also connected to the output of the pump 34.

The above described system may be operated as follows: The valves 60, 64 and 72 are closed and contaminated oil received through line 30 is delivered to the tank 42. Alkali is added and the mixture agitated and heated. After being allowed to settle the lighter oil phase is drawn off through íine 50 and heavier waste removed through line 48.

Decolouring agent such as Activated Earth is added to tank 54 and the oil is agitated and heated. Valve 40 is then closed, and valves 60 and 64 opened. Oil is transferred from the tank 54 through lines 58 and 62 to the filters and back to the tank 54. Finally valve 64 is closed and valve 72 opened and the treated oil obtained from line 70.

It is to be understood that the invention is not restricted to the specific apparatus and process just described. If desired the contaminated oil can be pre-treated to remove some solid particles and/or to lower the viscosity by heating.

The apparatus can be fixed or mounted on a suitable trolley. The sequence of steps may be manually or automatically controlled.

Claims

CLAIM

A process and apparatus for the treatment of contaminated fluids with particular reference to the purification of cooking oil, lubricating oil, insulating oil, fuel oil and the like.

The free fatty acid in the oil is neutralised by an alkali and the oil phase separated out.

Discoloured oil is further treated by Activated Earth to remove discolouration.

Theneutralised, decoloured oil is filtered and polished through a sub micron filter to remove suspended solid particles.