Patent GB-681302-A (GB)
Title: A method and apparatus for draught sintering
IPC: F27B21/06
Filed: 1950-05-02
Abstract: 681,302. Sintering process and apparatus. ROLFSEN, O. May 2, 1950 [May 4, 1949], No. 10768/50. Class 82(i) In a process for draught sintering using superposed grate pans charged with material to be sintered, the uppermost of which is constantly open to the atmosphere, the lowermost, at its bottom side being connected to a source of suction, whereby combustion of the charge is maintained and the uppermost pan being removed from the stack when burnt down and a fully charged pan being simultaneously inserted at the bottom of the stack, the process is so conducted that, by constantly maintaining a stack of several pans. the uppermost of which is being cooled by fresh air whilst the lower most is being heated an intermediate pan in which combustion is taking place has a relatively high temperature and at intervals the stack is lifted and a freshly charged pan is inserted thereunder. In the apparatus shown in Fig. 1 a stack of pans 1 is periodically lifted and the uppermost pan is engaged under its flange by means on both sides of the pan, said means being movable to and from the stack and including rollers 6 on which the pan is withdrawn to a discharging device 15 in which it is inverted for emptying. The pan is then passed by driven rollers under a charging station where it is filled with fresh material by screw conveyers 25 and is then ready to be again inserted in the stack. Meanwhile a charged pan is moved from an air-lock chamber 32, isolated from the air by pressure-operated gate 33, into position at the bottom of the stack which is lowered on to it. In order to prevent ingress of air to the stack during this operation, other than through the uppermost pan, the lower end of the stack is enclosed in an air-tight chamber 31 having an upper portion sealed by contact with the flanges of the pans moving upwards through it, and being connected to the air-lock chamber 32 by a pressure-operated gate 34. The pans have hollow side walls and grate bars and are provided with connecting devices for passing a cooling medium through the pans in series while they are in the stack. These devices include valves which provide a passage for the cooling medium from one pan to the next while it is in the stack and which automatically shut when the pan is removed from the stack. Cooling medium is circulated by pump 57 to the lowest pan, passes up through each pan in succession and passes then through a heat-exchanger 61. Fig. 5 shows the mechanism for periodically raising the stack comprising lifting arms, operated by pressure cylinders 40, the outermost ends of which carry rollers 43 bearing against the side walls of chamber 31, the innermost ends engaging the flange of the lowest pan during lifting. On insertion of the new pan the arm 42 on being lowered is moved aside as it passes the flange and then returns to its normal position as shown. The device for removing pans comprises pivoted arms 13 carrying rollers 6 and moved to and from the stack by pressure cylinders 14. The upper part of chamber 31 forms a shaft 45 which closely surrounds the stack over a height which is greater than that of one pan. Sealing is ensured by resilient packing means round the edge of each pan flange, which closely engages the shaft. This packing means is formed with internal hollow spaces in communication with the cooling medium space of the pan itself. As shown in Fig. 5 the grate bars of each pan are so situated that a free space exists between the charges in successive pans to ensure uniformity of the gas stream and heat radiation from each pan to the one below it.