초록 ▼

An improved method for controlling the fluidized dense catalyst phase temperature in the regeneration zone of a fluid catalytic cracking unit. In this method, the level of the fluidized catalyst bed above the riser discharge in the reaction vessel is adjusted in response to a change detected in the

An improved method for controlling the fluidized dense catalyst phase temperature in the regeneration zone of a fluid catalytic cracking unit. In this method, the level of the fluidized catalyst bed above the riser discharge in the reaction vessel is adjusted in response to a change detected in the temperature of the fluidized dense catalyst phase of the regeneration zone. Adjustment of the catalyst bed level in the reaction zone affects the coke laydown on the catalyst in the reactor and, consequently, the amount of heat liberated in the regeneration zone upon combustion of the coke contained in the partially deactivated catalyst. A reactor bed level is attained where the resulting coke laydown on the catalyst is sufficient to maintain the desired temperature in the fluidized dense catalyst phase. Also, as a part of this improved method, the amount of oxygen-containing regeneration gas supplied to the regeneration zone is adjusted to provide sufficient oxygen to effect substantially complete combustion of the coke to carbon dioxide and to maintain the oxygen content of the flue gas at a desired level within the range of from about 1 to about 10 mol %. Maintaining the oxygen content of the flue gas within this range provides a flue gas having a carbon monoxide content of from 0 to 500 ppm. The residence time of catalyst in the regeneration zone fluidized dense catalyst phase is adjusted to provide a regenerated catalyst with a low level of residual carbon-on-regenerated-catalyst.

대표청구항 ▼

In a process for continuous fluidized catalytic cracking of petroleum feedstock wherein a hydrocarbon charge stream is contacted with a zeolitic molecular sieve type catalyst in a reaction zone comprising a substantially vertical riser transport reaction zone discharging at its upper end into the up

In a process for continuous fluidized catalytic cracking of petroleum feedstock wherein a hydrocarbon charge stream is contacted with a zeolitic molecular sieve type catalyst in a reaction zone comprising a substantially vertical riser transport reaction zone discharging at its upper end into the upper portion of a reaction-separation zone wherein products of reaction are separated from partially deactivated catalyst containing coke deposits thereon and said partially deactivated catalyst is withdrawn from said reaction-separation zone and contacted with a stripping medium effecting displacement of occluded and accompanying hydrocarbons from said partially deativated catalyst, stripped catalyst is passed to a regeneration zone wherein a dense phase fluidized bed of said catalyst is contacted at elevated temperature with an oxygen-containing gas effecting combustion of said coke and regeneration of said catalyst, and regenerated catalyst is introduced into the lower portion of said riser transport reaction zone into contact with fresh hydrocarbon charge, the improvement which comprises establishing and maintaining within said reaction-separation zone a fluidized dense phase catalyst bed above the level of said riser discharge, maintaining a substantially constant level of conversion of said petroleum feedstock in said riser transport reaction zone, withdrawing catalyst from said reaction-separation zone at a rate sufficient to maintain said dense phase fluidized bed level of catalyst above said riser transport reaction zone discharge level, supplying oxygen-containing regeneration gas into said regeneration zone in an amount sufficient to consume substantially all of said coke on said catalyst with the production of a flue gas comprising carbon dioxide and oxygen and substantially free from carbon monoxide, detecting the temperature of said fluidized bed of catalyst in said regeneration zone, increasing the level of said fluidized bed of catalyst maintained in said reaction-separation zone when said temperature in said regeneration zone decreases thereby increasing the amount coke deposited on said catalyst, and decreasing said level of said fluidized bed of catalyst in said reaction-separation zone when the temperature in said regeneration zone increases thereby decreasing the amount of coke deposited on said catalyst, and thereby maintaining the temperature of said fluidized bed in said regeneration zone at a level sufficient to ensure substantially complete consumption of coke and carbon monoxide in said regeneration zone and below that at which substantial catalyst deactivation takes place, and discharging from said regeneration zone catalyst substantially free from coke and flue gas substantially free from carbon monoxide.