Catalyst – solid sorbent – or support therefor: product or process – Regenerating or rehabilitating catalyst or sorbent – Gas or vapor treating
Patent
1995-11-13
1998-06-30
Griffin, Walter D.
Catalyst, solid sorbent, or support therefor: product or process
Regenerating or rehabilitating catalyst or sorbent
Gas or vapor treating
502 41, 208113, 208160, B01J 2034
Patent
active
057733791
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns the use of an array of specially wound tubes in a fluidised or mobile bed heat exchanger. It generally concerns a process for thermal regulation or control in a continuous fluidised or mobile bed treatment process for powdered solid. The invention particularly concerns a process for regeneration of a used catalyst by heat exchange in a fluidised bed. The process is particularly applicable to the regeneration of catalysts which are particularly heavily loaded with hydrocarbon residues and coke following reaction with a hydrocarbon feedstock. It can apply to catalysts for hydrotreatment, hydrocracking or catalytic cracking, reforming catalysts or to any contact mass used, for example, in thermal cracking processes.
By way of illustration, we shall describe the use of an array of tubes in a fluidised bed process for regeneration of a used catalyst from a catalytic cracking process using heavy feedstocks having a high Conradson carbon residue such as atmospheric pressure residue, vacuum residue, or deasphalted residue, these residues being capable of hydrotreatment.
The process is particularly applicable to temperature control.
BACKGROUND OF THE INVENTION
Catalytic cracking processes convert hydrocarbon feedstocks into lighter products such as petrol. The feedstocks were initially fairly light, for example gas oils, and in order to achieve maximum conversion efficiency using highly active zeolite catalysts, it was necessary to remove the maximum amount of coke which deposited on these catalysts and reduced their activity. This was carried out in a regeneration step at a temperature of between 520.degree. C. and 800.degree. C.
Increasing demand for fuels led refiners to use heavier and heavier feedstocks, containing high boiling point hydrocarbons, with boiling points of more than 550.degree. C., for example, and a high Conradson carbon residue or high concentration of metals. Large quantities of coke and heavy hydrocarbons can become deposited on the catalyst during the catalytic cracking phase. Combustion regeneration releases a large amount of heat which can cause the apparatus to deteriorate and deactivate the catalyst, particularly when exposed to temperatures of greater than 800.degree. C. for long periods. It is therefore essential to control catalyst regeneration. This problem is particularly prominent when existing technology essentially designed for the treatment of conventional feedstocks is employed in a process using much heavier feedstocks.
The following patent documents illustrate the state of the art: EP-A-0 092 065, U.S. Pat. No. 2,963,422, EP-A-0 197 486, EP-A-0 153 214, EP-A-192 906 and EP-A-0 093 063. In addition, European patent EP-A-0 403 381 describes a double chamber heat exchanger connected to a catalyst regenerator by a single entrance and exit opening, which limits the cooling efficiency of the exchanger.
The prior art is further illustrated by U.S. Pat. No. 4,434,245 which describes thermal exchange of a catalyst which has been removed from a release zone located above a combustion zone and comprising vertical bayonet tubes. The drawback here is that a limiting layer of defluidised catalyst located at the tube walls flows along the tube and reduces thermal exchange.
Complex and cumbersome technology is usually required to overcome this problem, thereby reducing the reliability of the system.
A horizontal tubular plate positioned in the thermal exchanger and supporting the tubes will maintain the mechanical integrity of the assembly. However, widely different temperature and pressure conditions in different parts of the plate, for example 730.degree. C., 3 bars on the catalyst side and 275.degree. C., 60 bars on the coolant water side, create intense stresses which affect the mechanical integrity of the assembly.
SUMMARY OF THE INVENTION
One object of the invention is to overcome the problems associated with the prior art and obtain maximal thermal exchange in the most homogeneous fashion.
The invention thus concerns a process for t
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Bonifay Regis
Gauthier Thierry
Hoffmann Frederic
Pontier Renaud
Griffin Walter D.
Institut Francais du Pe'trole
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