GB282321A - Methods of, and apparatus for, purifying and drying oil separated from aqueous emulsions - Google Patents

Abstract

282,321. Ellis, G. B., (American Sheet & Tin Plate Co.). Sept. 13, 1926. Fats and fatty oils, recovering and purifying.- Oil, such as palm oil, separated from an emulsion of oil and water, is purified and dried by heating the oil until substantially all the water content is changed to vapour and separating the vapour from the oil. The oil, after passage through a screen 48, Fig. 2, which removes solid matter, may be collected in a tank 50 fitted with a steam coil 51, from which it is pumped through a coil 54 located in a steam heated drying drum 55 which raises its temperature to 300‹ F. and vaporizes its water content before it is discharged into a stack 56. The water vapour passes up the stack, and the dry oil flows through tanks 59, 60, maintained at 300‹ F., to a centrifuge 62 for final purification. The invention is described as one step in a process for the removal, purification and recovery of oil from tin plate. As shown in Fig. 1, tinned plates form a pot A, after passage through a body of palm oil 9, are fed into a washing-tank C filled with a hot soda ash solution and supplied constantly with water from a pipe 12 and with further soda ash as required. The plates are pressed through the solution by pairs of rolls 15, 16, the lower roll of the first pair and the upper roll of the second pair being of smaller diameter and having a greater surface speed than the remaining rolls and being fitted with a fabric or rubber covering 17, whereby the plates are scoured and freed from oil, and an emulsion of the latter with the solution is formed. Similar pairs of rolls 19, 20, 21 serve to polish and dry the plates before they pass to a branner 24. Emulsion from the tank C, zinc chloride and other soluble impurities having passed from the oil into the aqueous solution, overflows through a pipe 29 and passes by a trough 31 into the heating and mixing chamber 33 of a tank D, Fig. 2, where a measured quantity of sulphuric acid is added from a tank 42 by a pump 43, and into which steam is passed from a pipe 39 to heat the mixture to, say, 140‹ F. The emulsion, thus broken, overflows into a chamber 34<a> and separates by gravity, the oil rising to flow over the inclined top of a wall 35 into a chamber 35<a>, this action being assisted by a steam coil 38, and the water passing away by a pipe 45, the top of which is about 1¢ ins. below that of the wall 35. Acids other than sulphuric acid, nitre cake, waste pickle liquor, lime, calcium chloride, iron or sodium sulphate, or alum may alternatively be used to break the emulsion, but in some cases the oil then settles out with any precipitate formed and the water rises in the chamber 34<a>; or the emulsion may be broken by centrifugal means, or the oil be extracted therefrom by a solvent. The oil collecting in the chamber 35<a>, which contains about 60 per cent of water, and is heated by the steam coil 41, is dried and purified as above described.