Patent GB-988855-A (GB)
Title: Material treatment apparatus
IPC: C11D13/12
Filed: 1961-05-10
Abstract: 988,855. Polymerization apparatus; continuous mixing apparatus. CRAWFORD & RUSSELL Inc. May 10, 1961 [May 10, 1960], No. 17020/61. Headings B1C and B1X. A material treatment apparatus comprises an outer cylindrical tube fitted with a heat exchange jacket, a cylindrical, double walled heat exchange tube inside of, spaced from, and coaxial with, the outer tube, means for circulating heat exchange fluid within the jacket and between the walls of the inner tube, a helical impeller inside the inner tube for moving materials through the inner tube and through the space between the outer surface of the inner tube and the inner surface of the outer tube, and at least one scraper which is rotatable around the inner tube within said space so as to scrape simultaneously both the outer surface of the inner tube and the inner surface of the outer tube. If desired, the outer tube may be disposed coaxially within an outer cylindrical shell provided with a heat exchange jacket therearound, with supplementary scrapers being supplied to scrape the inner surface of the cylindrical shell and the outer surface of the heat exchange jacket of the enclosed outer tube. Fig. 1 shows outer tube 2, with its heat exchange jacket represented by wall 20 and space 22, joined by flange 4 and bolts 6 to removable head 8 which possesses inlet and outlet means 10 and 12 and which through bearing 14 carries shaft 16 which is drivable e.g. by an electric motor or hydraulic turbine. Shaft 16 supports helical screw 38 which is fitted with vertical, circumferentially spaced scrapers 42 which may be pivotable but which point forward at a slight angle to the direction of rotation and scrape the wall 29 of the inner tube 28. Tube 28 with its heat exchange jacket represented by space 31 is open ended and is supported in position clear of the end closure of outer tube 2 by the feed pipe or pipes 32 to the heat exchange jacket, and the legs 34. Shaft 16 also carries arm 44 which supports vertical channel beams 46 and 48 to which are attached, so that the blades point forward in the direction of rotation, the agitating-scraping members 50 which are shown in detail in Fig. 5. The blades 52 are prevented by spacing block 54 from forming an inclined angle of less than about 110 degrees. This, together with the rotation and the viscosity of the mix, ensures that the scraper blades are forced against the walls and thus compel the outer layers of the mix to return into the mass and improve the mixing. The scrapers occupy the whole length of the annular space of the reactor and consequently the mass of material is moved forward with a rotational motion which coupled with the vertical motion caused by the helical screw causes the material to take a helical path past the heat exchange surfaces. As shown in Fig. 5, it is advantageous if the blades and channel bars are slotted so that unmixed material does not build up in front of the agitating-scraping members. The ends of the bars 46 and 48 may be fitted with scraping blades 70 and 72 to agitate the material passing through the space between the end of the inner tube 28 and the end closure of the outer tube. This apparatus can be used to advantage in polymerization reactions, soap manufacture, grease making and in the bodying of natural oils, in all of which the product is viscous and problems of mixing and either the supply or removal of heat arise. Specification 988,856 is referred to.