Resid conversion catalytic cracking

China Petrochemical Technology Co., Ltd. Propylene or Iso-olefln Vacuum gasoil (VGO), vacuum resid orVGO blended with deasphalted oil Deep catalytic cracking (DCC) conversion technology, produces light olefins (ethylene, propylene and butylenes), LPG, gasoline, middle distillates, etc., from hydrocarbon feedstocks NA NA... 

The CFB catalytic cracking reactor plays an important role in the petroleum industry because of its better gas-solids contact and narrow residence time distribution, but its non-uniform radial flow structure and the extensive backmixing of gas and solids lead to a lower conversion rate and poorer selectivity to desired intermediate products [14]. 

Fuel Gas yield Thermal vs. Catalytic Cracking. A higher ratio of fuel gas/iso-butane was found in the case of the MR, which is to be expected with a relatively low catalyst volume fraction and longer residence time of the hydrocarbons in the reactor (see Table I). With increasing catalyst fraction (or conversion) the ratio decreases due to the formation of more iso-butane. A reduction in contact time will also result in a lower ratio, because fewer thermal cracking reactions will take place. 

RFCC (resid fluid catalytic cracking) is one of the processes for the conversion of heavy oils in modem refineries. The problem with vacuum residue as FCC feedstock is quick deactivation of catalysts by the coking of asphaltene fractions and the deposition of metals involved in metallorganic polycyclic compounds. Therefore, developing novel zeolites to achieve metal tolerance has long been a goal of catalyst researchers... 

Catalytic coke is a byproduct of the cracking of FCC feed to lighter products. Its yield is a function of conversion, catalyst type, and hydrocarbon/catalyst residence time in the reactor. 

In quite a different application, a novel approach for producing olefins via a hydrocarbon-steam cracking process, without the use of a catalyst, was demonstrated to benefit from the use of a honeycomb monolithic catalytic reactor [28]. A typical problem associated with cracking processes of this type is maintaining the appropriate combination of heat transfer and residence time, which, if not balanced, will lead to either poor conversion... 

The conversion and the coke yield as a function of residence time with different CTOs are shown in figure 4a and 4b, respectively. The conversion in the absence of catalysts is a measure for the amount of thermal cracking. At a residence time of 4 s it is at maximum 6wt%. The catalytic conversion after 0.15 s is remarkably high, over 30 wt%. The conversion increases proportionally with residence time up to a conversion of ca. 75 wt%, then levels off and reaches a maximum value of 90-95 wt% after 3-5 s. The coke yield (figure 4b) is hardly influenced by residence time, except for a minor increase at a CTO of 6. Clearly, almost all the coke has been generated within 0.15 s. 

The conversion of a hydrowax feedstock due to thermal cracking at a residence time of 4 s was at maximum 6 wt%. The product yields obtained catalytically could all be described by the same function of conversion, regardless the reactor length or the CTO used. Up to a conversion of 95 wt% no gasoline over-cracking has been observed. 

Visbreaking is a thermal process (non-catalytic) that reduces the viscosity of the residual oil. The mild cracking conditions used in visbreaking favor a high yield of naphtha with less gas and coke production. Visbreaking process achieves about 30% of residue conversion to lighter products. Low residence times are required to avoid coke formation. 

---