GB654686A - Improvements in or relating to the handling of solid carbonaceous materials in the heat treatment thereof - Google Patents

Abstract

654,686. Carbonization and gasification of carbonaceous solids. STANDARD OIL DEVELOPMENT CO. March 2,1948, Nos. 6606 and 6607. Convention dates, May 17, 1947. [Class 55(i)] In the carbonization or gasification, by fluid-solids technique, of coals or the like which plasticize and agglomerate at the process temperatures, preheating to the plasticizing temperature is effected in a chamber 10, which is separate from the treatment chamber 20, the duration of treatment in the chamber 10, however, being so short that substantial carbonization of the coal in that chamber is avoided. coagulation being prevented by mixing the fresh coal with non-plasticizing residues from the treatment chamber 20. The coal is supplied from a hopper 1 to the bottom of the preheater 10, fluidizing gas, e.g. steam, flue gas, product gas, being supplied through the pipe 12. Air or oxygen for supporting combustion to the extent required for maintaining the necessary temperature in the chamber 10 is supplied to the pipe 12 through the pipe 16. The heated coal is discharged, with the fluidizing gases, through a regulable opening 18 into the chamber 20, the resulting drop in gas flow speed permitting the solids to fall on to the dense fluidized bed 22. Alternatively, if it is desired to exclude the gases from the chamber 20, the preheated solids are separated from the gases in a separator 42 which discharges the solids into the chamber 20 through a pipe 44 and eliminates the gases at 46. A valve 54 in the pipe 52 regulates the residue supply to the preheater 10. The bed 22 is fluidized by preheated steam or product gas supplied through a pipe 24, or, alternatively, the product gas from the gas-solids separator 30 may be tapped by a pipe 36 and recycled by a blower 40. Oxidizing gas may be supplied to the pipe 36 by a branch 37, to maintain the necessary temperature in the chamber 20. Some of the carbonaceous residues from the chamber 20 are led by a pipe 64 to a combustion chamber 66 supplied with air by the pipe 16, the highly heated residues being passed at 74 to the pipe 12 to assist in maintaining the temperature in the chamber 10. The chamber 20 may be used as a water gas generator by raising the temperature in the preheater 10 or by returning part of the hot residue from the combustion chamber 66 to maintain a temperature of 1500‹-2000‹F. in the chamber and supplying sufficient steam through the pipe 24. In a modification, the preheating chamber is placed centrally within a circular carbonization chamber, the preheating chamber being open top and bottom so that the carbonaceous material rises therein with the fluidizing gas to overflow into the dense fluidized bed in the annular carbonization space. The fresh coal is fed, e.g. by a worm conveyer to the bottom of the preheater and is mixed with the descending residue from the carbonization space which is in free communication with the preheater. The proportion of residue to fresh coal may be controlled by valve means at the bottom of the carbonization space. A development of this modification is shown in Fig. 3, fresh coal being supplied to the preheater 330, from a hopper 301, by an aerated pipe 305, and mixed with residue from the space 322. The upflow in the preheater is maintained by steam supplied through pipe 315, additional steam for fluidizing and/or reaction being supplied to the space 322 through lines 340. The heat required for the process is generated in a separate combustion chamber 350, in which carbonaceous residues from the space 322 are burned with air supplied by a blower 309 through a cleaner 311, and the heat transfer is effected by hot solids passing through the line 361 to the bottom of the preheater 330. If gasification is to be effected in the space 322, temperatures of 1600‹-2500‹F. are maintained. Stripping gases admitted at 337, prevent product gases from passing to the combustion chamber 350.