Patent GB-747819-A (GB)
Title: A continuous process and equipment for continuously producing acetone using calcium acetate liquor as starting material
IPC: C07C45/54
Filed: 1952-08-08
Abstract: A continuous process for producing acetone, using calcium acetate liquor as starting material, comprises the steps of providing a closed surface defining an enclosed space, heating said surface to calcium acetate decomposing temperature, providing a thin spray of water containing impure calcium acetate liquor, causing displacement of said spray with unidirectional rectilinear motion in said enclosed space, whereby a thin coating of calcium acetate liquor is applied to successive perimetral portions of said heated surface, permitting evaporation of water contained in said thin coating of liquor to produce dry impure calcium acetate at and adhering to said heated surface, permitting said calcium acetate to remain adhered to the surface for a time sufficient to decompose the dry impure calcium acetate to produce gaseous products comprising acetone and acetone oils in gaseous state, withdrawing the gaseous acetone and acetone oils from the enclosed space, concentrating said gaseous products, separating therefrom a crude acetone fraction and an acetone oil fraction and separately rectifying the two fractions.  The calcium acetate liquor may be obtained by neutralizing with calcium hydrate the pyroligneous acid obtained by the carbonization of wood (see Group XII and Specifications 747,820 and 747,821).  In the Figures warm pyroligneous acid, free from oils and tars, which has been separated from the wood carbonization products is neutralized with calcium hydrate in tank 201.  The resulting solution is clarified in pool 155, and then forced by pump 229 (Fig. 2), through duct 231 to the atomizing head 398 (Fig. 16) of a piston 399 mounted on stem 400, the atomizing head being slidably arranged in the calcium acetate decomposition cylinder 102 which is housed in a heating chamber of furnace 65 and is provided at its ends with sinks 401.  The operation of the piston is synchronized with that of the pump 229, so that during the working stroke of the piston the calcium acetate liquor is projected in the form of a finely-divided spray through a plurality of spaced nozzles which are provided in the upper half of the atomizing head.  The spray forms a film on the internal wall 407 of the cylinder 102 where the water rapidly evaporates and drying of the paste occurs followed by its subsequent decomposition, the decomposition temperature exceeding 300 DEG  C.  The piston incorporates a scraper the free edge of which is in scraping contact with the internal wall of the cylinder whereby the residual ashes are discharged into the sinks, the major proportion being discharged into the left hand sink (Fig. 16).  The operation of the calcium acetate decomposition cylinder and its accessories is the same as that of the tar cracking cylinder 101 (Fig. 2) and its accessories used in another stage of the wood carbonization process-see also Fig. 6 (not shown).  The cylinder 102 is provided at its upper middle part with an opening 404 having an exit duct 405 which extends into dephlegmator 406 where the heavy acetone oils and part of the water are collected.  The remaining gases and vapours rise into the concentration tower 408 formed of a plurality of superposed cascade containers 409 which are adapted to successively discharge overflowing liquid from one container into the next lower container, the liquid being finally discharged into the dephlegmator.  The uncondensed vapours enter the multi-tubular condenser 411 where they are further concentrated, a large portion of the water being returned through reflux pipe 412 to the tower 408.  The <PICT:0747819/IV(a)/1> precipitating tank 416 where the acetone oils separate and float on the surface of the acetone and are then passed to tank 417. The aqueous acetone solution from tank 416 is used as refrigerant liquid for the tar cracking cylinder 101 where it becomes reheated and is then passed via line 277 to the lower part of the acetone rectifying tower 424.  The latter is provided with a bottom boiler 428 and has lower and upper bubble container sections 433 and 434, the upper section being separated from the lower section by an intermediate boiler 435 into which enters the upper part of the lower section of bubble containers 433.  Discharge ducts 436 connect the bottom section of the upper section of bubble containers with the lower part of the boiler 135.  The temperature in boiler 428 is adjusted so that the acetone vapours rise through the lower bubble container 433 and reach the bubble container 4331 where they are uncondensed vapours are cooled in refrigerator 414 where a crude acetone solution is obtained which is passed through pipe 415 into a dephlegmator 566 from which the liquid is led to a treated with an agent such as an alkaline solution, e.g. of sodium carbonate, sodium hydrate, or calcium hydrate, which is supplied from tank 439, so as to precipitate the remainder of the oils and neutralize any phenols present.  The pure acetone vapours then pass through condenser 446 to remove any entrained liquid and then to a refrigerator 448 where the vapours are liquefied, the purified liquid acetone being collected in tank 451.  The acetone oils and water from the dephlegmator 406 are collected in tank 454 from which the water is run to waste through pipe 456 while the acetone oils are pumped to tank 417 from which the combined acetone oils are pumped through line 462 to an acetone oil rectifying tower 464 where the acetone oil vapours and water vapours pass through bubble containers (not shown), the heavy oils being taken off at the lower part of the tower by pipe 469 and passed through refrigerator 470 to the tank 471.  The medium oils are taken off by pipe 472 via refrigerator 473 to tank 474 while the light acetone oils are removed at the top and passed via refrigerator 476 to the tank 477.  Other products recovered from the gaseous products formed in the wood carbonization process include methanol containing butanone, methyl acetate, acetone, acyclic amines, and pyridine as impurities; benzenic hydrocarbons and saturated acyclic and alicyclic hydrocarbons from the tar cracking operation, and creosote, cineol, and phenols such as phenol itself and cresol which are also formed in the tar cracking operation.  A mixture of the hydrocarbons and methanol containing the specified impurities is stated to be of value as a carburetant.