Time factors catalytic cracking

The third factor is that the FCC feedstock is getting heavier. As the feed gets heavier, the boiling point increases, which makes feed vaporization more difficult. At the same time, the viscosity of the feed also increases, which makes feed atomization more difficult. Thus better feed atomization must be achieved to disperse the feed into even finer droplets in order to vaporize the heavier feed in time for catalytic cracking reactions to take place in the riser reactor within seconds. 

Pressure Vessels. Refineries have many pressure vessels, e.g., hydrocracker reactors, cokers, and catalytic cracking regenerators, that operate within the creep range, i.e., above 650°F. However, the phenomenon of creep does not become an important factor until temperatures are over 800°F. Below this temperature, the design stresses are usually based on the short-time, elevated temperature, tensile test. 

The cracking reaction in all catalytic cracking processes is affected by the following factors (2) catalyst type and inherent activity charge stock characteristics and midboiling point space rate, usually measured in terms of liquid oil volume per volume of catalyst per hour ratio of catalyst to oil, the amount of catalyst in the reaction zone per unit of oil reacted, which in the fixed-bed process becomes the ratio of reciprocal space rate to time on stream, and in the moving-bed process is the ratio of catalyst rate to oil rate temperature and oil partial pressure. 

That is, the space velocity is only about 1/16 as high and the catalyst/oil is 16X as great. These two factors are considered (O equally important in catalytic cracking. So we have an activity advantage of more than 16 x 16 or 256 times for the rare earth-acid catalyst. Conservatively, we said the rare earth form was at least 100 times and the other forms at least 30 to 50 times as active as standard silica-alumina catalysts. 

The increased performance meant that Allied planes were better than Axis planes by a factor of 15 percent to 30 percent in engine power for take-off and climbing 25 percent in payload 10 percent in maximum speed and 12 percent in operational altitude. In the first six months of 1940, at the time of the Battle of Britain, 1.1 million barrels per month of 100-octane aviation gasoline was shipped to the Allies. Houdry plants produced 90 percent of this catalytically cracked gasoline during the first two years of the war. (12)... 

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