Patent GB-526744-A (GB)
Title: Improvements in or relating to the treatment of wax-oil or wax-wax mixtures
IPC: C10G73/06
Filed: 1939-02-17
Abstract: 526,744. Dewaxing oils ; fractioning waxes. SCHUTTE, A. H. Feb. 17, 1939, Nos. 5341, 5342, 5343, 5344 and 5345. Convention dates, Feb. 25, 1938, May 19, 1938, May 19, 1938, May 19, 1938, and Sept. 29, 1938. [Class 91] Oils are dewaxed and waxes are de-oiled by emulsifying the liquefied material with a non- reactive immiscible liquid prior to chilling ; a diluent may be present and the mixture may be aerated before emulsification. The filtered or otherwise separated wax may be fractioned by washing at different temperatures with the immiscible liquid or the diluent. Naphtha is the preferred diluent. Suitable immiscible liquids are water, brine, calcium chloride brine, lower alcohols, glacial acetic acid, and metal alloys ; preferably, when amorphous wax is to be separated a liquid is used which crystallizes sharply at a higher temperature than the congealing point of the wax, and non-freezing liquid when the wax is crystalline. Materials treated include lubricating oils, diesel oils, slack wax, wax fractions, and commercial mixtures of waxes. In an example, a wax-bearing oil is pumped from a pipe 10 to a mixer 12 supplied with water by a pump 50 and preferably pre-cooled naphtha or other diluent by a pipe 21 ; the emulsion is passed through a cooler 13, thinned if necessary with naphtha, from a pipe 22, passed into a chiller 14, and discharged by a pipe 20 on to a filter 24 of the Fourdrinier type. The filtrate is withdrawn from the suction box 25 and taken by a pipe 25a to a de-aerating drum 26 maintained under reduced pressure by a vacuum pump 27 ; it is then pumped through a pipe 28, the cooler 13, and a heat-exchanger 29 into a separator 30; the water separating out is taken by a pipe 40 to a separator 42, and is thence returned by a pipe 49 and the pump 50 to the mixer 12, water being added by a pipe 51 if required ; the oil separating out is discharged through a pipe 31 and a heat-exchanger 32 into a stripper 33 from which naphtha vapours flow by a pipe 34 to a condenser 48 and the separator 42 ; the separated naphtha is forced by a pump 54 through a pipe 53, and, with any added at 55, through a pipe 55a, to a pipe 56 and the pipes 21, 22, direct and/or through a cooler 59 ; the dry wax-free oil is removed from the stripper 33 by a pump 43 and passed to storage through the heat-exchanger 32, a pipe 44, the heat-exchanger 29, a pipe 45, and a cooler 46. The wax-cake on the filter 24 is washed with water or with the naphtha from the pipe 55a ; preferably the washing liquid from the delivery nozzles 62, 61, 60 is at increasing temperatures whereby waxes of different M.P. are received in the suction boxes 70, 71, 90, and a high M.P. wax is delivered to the chute 93. The "foots" in suction-boxes 70, 71 may be withdrawn through a pipe 73 to a separator 74 connected with the vacuum pump 27 by a pipe 27a, and thence forced by a pump 76 along a pipe 77 to be recycled with fresh oil admitted by the pipe 10; or it may be taken by the pipe 25a to the drum 26 with the dewaxed oil from suction box 25. The waste liquid and liquefied wax in suction box 90 is drawn through a pipe 91 to the chamber 75 of separator 74, and passed by a pipe 75a to a heater 78 and a separator 79 ; the wax is removed through a pipe 82 and heated by an exchanger 83 before entering a stripper 84; residual diluent passes by a pipe 86 to the condenser 48 and separator 42 ; the wax is discharged through a pipe 87 and the exchangers 83, 88 to storage. The wax discharged into the hopper 93 is melted by a coil 94, and discharged, or is forced by a pump 95 through a heat exchanger 96 to a separator 97 ; the separated wax is passed through a pipe 98 and a heat exchanger 99 to a stripper 100, and, freed from diluent vapour taken by a pipe 105 to the condenser 48, is discharged to storage through a pipe 102 and the heat-exchangers 99, 103. When the oil treated is so thin that a diluent is not used, the diluent-recovery apparatus is omitted. Fig. 2 shows a modified apparatus for purifying or fractioning wax. 'The initial wax is pumped through a pipe 141 into a tank 142 containing a heating coil 143, and removed as desired by a pump 144 through a cooler 145 to a pipe 146 into which water is fed by a pump 147, a pipe 148, and a heater 149; air or other gas may be supplied by a compressor 150 through a pipe 151 ; the mixture passes to an emulsifier 152, e.g., a rotary pump which recirculates through a by-pass 153 and discharges the emulsion through a valve 154 and a cooler 156 reducing the temperature sufficiently to precipitate the wax fraction of high M.P.; the whole is collected in a surge tank 157 and passed by a pipe 158 to a high speed centrifugal filter 159. The filter cake is washed with water or mixed water and foots oil from a pipe 167 during rotation of the centrifuge, and preferably again with water at a higher temperature just below the M.P.; the oil-freed wax is then dried by further rotation, and discharged into a storage tank 163 for removal as desired through a pipe 164. The filtrate of foots oil and water is discharged through a pipe 161 into a tank 162 ; it may be passed through a pipe 165, a cooler 166, and the line 167 and used to wash the wax cake in the centrifuge 159 ; or the foots oil may be taken off through a pipe 168 and a heat-exchanger 169 to an emulsifying pump 172, a valve 174, a cooler 176, surge tank 177, a pipe 178, and a centrifugal filter 179; the wax cake is washed with water from a pipe 187, and discharged through a pipe 184 to a tank 185 for removal as desired through a pipe 186 ; the filtrate is discharged to a tank 181, and may be removed through a pipe 182 or pumped through a pipe 183 to the pipe 141 for recircuiting.