TUBULAR HEAT EXCHANGER FOR THE CONTINUOUS DIGESTION OF SOLID MATERIALS WITH LIQUIDS

摘要

1473821 Tubular heat exchangers VEREINIGTE ALUMINIUM-WERKE AG 24 Feb 1976 [2 April 1975] 07316/76 Heading F4S A tubular heat exchanger comprises a substantially U-shaped tube 1 conveying a first fluid in heat exchange with a second fluid flowing through another tube 2 extending through the tube 1 and consisting of a plurality of tube loops interconnected outside the tube 1 so as to form a continuous passageway for the second fluid. Preferably portions of the tube 2 cross each other either inside (e.g. at points A, B, Fig. 1) or outside (e.g. at points C, D, Fig. 2) the tube 1. The arrangement of the tube 2 may include return bends outside the tube 1 which, as shown in Fig. 3, may be enclosed within insulating material 3. Said bends may be joined by individual connections 4 (or alternatively by a common connector 5, Fig. 6) to the ends of the tube 2 projecting from the tube 1. Fig. 5 shows an arrangement comprising two of the tubes 1 placed end to end. In this case short detachable tubes are removable by means of joints 4 to enable the tube 2 to be cleaned. Water-jet cleaning means may be located within the tube 1. In use, a fluid medium such as a suspension of bauxite in sodium hydroxide passes through the tube 2 and is heated by a medium such as steam, a molten salt or a hot liquor flowing in the tube 1.