Tube furnace for carrying out gas reactions in ceramic tubes

摘要

A tube furnace for carrying out gas reactions, preferably continuously, and more especially at temperatures higher than 900 DEG C., in ceramic reaction tubes freely suspended within a heating chamber in the furnace, comprises a plurality of such reaction tubes connected to a common gas supply means and a common gas discharge means, each tube being adapted during the running of the furnace to be shut off individually and to be separately replaced, wherein the reaction tubes are suspended in the form of a bundle from a head which may be equipped with cooling elements and which contain ducts leading one from each tube to a common gas chamber, and wherein a closable tube union which terminates at its upper end above the head is positioned above each duct and is adapted to be lowered so that a plate-shaped lower end engages the upper opening of the duct and thereby shuts off the latter and the associated reaction tube from the common gas chamber. In the embodiment shown in Fig. 1, the reaction tubes 23 are suspended from a head 24 in a heating chamber 22 divided into two sections 221 and 222 by a restriction 26 which leaves a passage around the tubes of approximately the same total cross-section as that of the tubes. The latter, which preferably have a wall thickness of 1-3 mm., pass through upwardly flaring conical openings in a plate 25. The heating chamber sections have respectively burner blocks 27 and 28 arranged in or discharging into said sections, and also have independent offtakes 231 and 232 leading to a recuperator and provided with separate draught regulators. The tubes may alternatively be arranged around a central heating chamber or around a central flue. Fig. 2 shows a head 31 with cooling chambers 33 receiving the tubes 32, and being closed by a cover 34 having a common gas chamber 35. A further cooling device, having ducts 36 forming extensions of the reaction tubes, is disposed between the head and the cover, and is secured thereto by latches 328. The tubes are secured by metal holders 38 having asbestos packing-rings 39 and a screw 322. The ducts 36 are closed by screwed valve-closed tubes 324 having a sealing element seating in recesses 326. A closing device, Fig. 3, may be disposed at the bottom of the tubes. A common gas chamber 41 is connected to the tubes 48 by a flexible union 46 and carries a control head 42 for each tube, said head containing a conduit 43 with a control sleeve 44 and a closure cover 45. The walls of the conduit 43 are formed with ducts 411 connecting the internal bore thereof with the chamber 41 and adapted to be closed by flexible packing 412 on the sleeve 44, when it is desired to close off a tube. Packing material may be introduced into a tube by this device. The furnace has been applied to the production of hydrocyanic acid from methane and ammonia using catalysts of the platinum group. Specification 815,531 is referred to.