Columns continuous catalyst regeneration

Description The process consists of a reactor section, continuous catalyst regeneration (CCR) section and product-recovery section. Stacked radial-flow reactors (1) facilitate catalyst transfer to and from the CCR catalyst regeneration section (2). A charge heater and interheaters (3) achieve optimum conversion and selectivity for the endothermic reaction. Reactor effluent is separated into liquid and vapor products (4). The liquid product is sent to a stripper column (5) to remove light saturates from the C6 aromatic product. Vapor from the separator is compressed and sent to a gas recovery unit (6). The compressed vapor is then separated into a 95% pure hydrogen coproduct, a fuel-gas stream containing light byproducts and a recycled stream of unconverted LPG. 

In the process, the catalyst is continuously separated from the mixture at the top of the reactor and sent to a regenerator where carbon and other contaminants are removed by blowing hot air irito the regenerator forming CO/CO9. From the top of the reactor, the product mbc moves to the separation columns where ethylene and propylene are separated from the heavier C4 products, any unreacted methanol, and the water that gets formed. 

In the process (Figure 8-12), the feedstock is vaporized upon contacting hot regenerated catalyst at the base of the riser and lifts the catalyst into the reactor vessel separation chamber where rapid disengagement of the hydrocarbon vapors from the catalyst is accomplished by both a special solids separator and cyclones. The bulk of the cracking reactions takes place at the moment of contact and continues as the catalyst and hydrocarbons travel up the riser. The reaction products, along with a minute amount of entrained catalyst, then flow to the fractionation column. The stripped spent catalyst, deactivated with coke, flows into the Number 1 regenerator. 

Cracking of n-heptane was carried out on catalysts USY-1 and U1F-25 in a continuous flow, fixed bed reactor (15), at 450 aC and atmospheric pressure. In all experiments, 0.223 g of zeolite catalyst, and 8.625 g of n-heptane were used. With each catalyst the reaction was performed at 75, 150 and 375 seconds of time on stream. The catalyst was regenerated "in situ" after each experiment by passing flow of air at 5209C during 4 hours, and liquids were analyzed by GC by means of a Porapak-Q silica and a S-30 columns respectively. 

The packed bed reactor is used to contact fluids with solids. It is one of the most widely used industrial reactors and may or may not be catalytic. The bed is usually a column with the actual dimensions influenced by temperature and pressure drop in addition to the reaction kinetics. Heat limitations may require a small diameter tube, in which case total through-put requirements are maintained by the use of multiple tubes. This reduces the effect of hot spots in the reactor. For catalytic packed beds, regeneration is a problem for continuous operation. If a catalyst with a short life is required, then shifting between two columns may be necessary to maintain continuous operation. 

---