GB753904A - Fluidised bed temperature conditioner and method of controlling temperatures of fluid process streams - Google Patents

Abstract

<PICT:0753904/III/1> A fluidized bed temperature conditioner for continuously controlling the temperature of a fluid stream of reacting materials at successive points along its path, comprises a housing (10, 12, 13) of which the lower portion is divided into compartments (A, B, C) by upright partitions (18, 18a), each of said compartments having means (e.g. 31) for admitting fluidizing gas thereto; means (52) for discharging gas from the upper part of the housing; means for independently controlling the temperature of a fluidizing bed maintained in each compartment; and one or more heat-conductive tubes (15) for said fluid stream, at least a portion of each tube lying within each compartment. The corresponding method of controlling the temperature of a process stream is not limited to the use of apparatus in which the compartments are in free communication above the partitions. The numerals refer to the illustrated apparatus, which also embodies the following features. The housing comprises a refractory bottom 10, side walls 12 and arch 13, and is divided into compartments by refractory partitions 18 and 18a, adjustably bolted to the bottom. The tubes 15 may pass through the partitions as shown or pass thereover, and may be in the form of coils. Hot combustion and fluidizing gases are supplied from a refractory combustion chambers such as 19 within which is a burner supplied with independently regulated fuel and primary and secondary air through pipes 25, 28 and 22 respectively, and pass through a duct 30 surmounted by a deflector 31. Several such arrangements may be employed in each compartment and distributing grids may also be used. Alternatively, combustion may be carried out above the floor 10. Additional cooler fluidizing gas may be supplied through ducts 36 from wind-box 35 from line 40, supplying e.g. atmospheric or preheated air and/or recirculated flue gas from duct 44. One or more compartments may have means for admitting a liquid to be vaporized and thus cool the fluidized heat-conducting solids, such as perforated pipes 47 supplied with liquid through pipe 51. Suitable adjustment of the pressure in the bed may be necessary to avoid recondensation of the liquid, and when starting up it may be necessary to introduce steam or other gas initially. Fluidizing gases emerge through a duct 53 and entrained solids are separated in cyclone 54 and returned to one of the compartments by dip leg 55: the levels in the various compartments are in this case maintained by overflow. In general the levels may be at or near the tops of the partitions, or (less desirably), slightly above. Suitable solids for use are metal oxides of the type used as catalysts and (preferably) sand particles of diameter 0.005-0.1 inch: the fraction of voids is usually 0.3-0.8; in order to obtain high heat transference, the "Reynolds number" (definition given) should be at least 2 and preferably above 5. Reference has been directed by the Comptroller to Specification 587,774.