GB693829A - Method and apparatus for pyrolyzing organic reactants - Google Patents

Abstract

<PICT:0693829/IV (b)/1> <PICT:0693829/IV (b)/2> The pyrolysis of organic compounds such as aliphatic acids and ketones in a tubular pyrolysis furnace is effected by generating primary hot combustion gases in a primary heating zone, introducing cooling fluid into said primary gases to obtain regulated primary combustion gases, passing said regulated gases into contact with a reaction tube, generating additional hot combustion gases in at least one other heating zone, passing these gases into contact with the reaction tube and into the regulated primary gases, and passing the organic compounds through the tube. The cooling fluid such as steam or inert gases introduced into the primary combustion gases regulates the temperature so that high BTU content fuel, e.g. butane or propane, may be used. A furnace 11 comprises preheat, super-heat, and pyrolysis chambers 12, 13, 14, respectively, containing connected tubular coils 15, 17, 18. Chambers 12 and 13 are connected by a passage 23, Fig. 4, which surrounds bottom partitions 24, 25 having ports 241, 251, in said chambers. Chambers 13, 14 are similarly connected by a passage 26. A tubular member 32, forming an extension of exit conduit 29, is disposed within coil 15, and a cylindrical member 33, closed at the top, within coil 17. Adjustable fuel burners 34, 35 are disposed in the primary heating zone below coil 18. Cooling jets 36 alternate with burners 35 in two vertical banks arranged to give tangential injection and rotation, Fig. 4. A ring 37 in chamber 14 has an inner ported partition, while adjustable burners disposed in the furnace wall fire tangentially into said ring generating a secondary supply of combustion gases which mix with the primary gases. Cooling fluid jets may also be provided. A tertiary supply of combustion gases is provided by burners firing into passage 26 in the direction of gas movement. Cooling jets may also be provided. Acetic acid vapours and catalyst may be introduced at 16 and products leave at 22 where ketene may be absorbed in glacial acetic acid to form acetic anhydride. A combustion gas temperature of 800-1100 DEG C. is preferred. The several chambers may be disposed vertically instead of side-by-side or a single long coil may be used. Examples describe the pyrolysis of acetic acid to ketene using propane as fuel. Other compounds which may be pyrolysed are acetone, methyl ethyl ketone, diethyl ketone, propionic and butyric acids.