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Beijing, China

Petroleum Refinery Engineering | Year: 2013

Here introduced are the process flows of low-temperature medium-temperature light paraffin isomerization processes widely applied in the industry, the octane number of isomerate, the main operating conditions and the production requirements, etc. The low-temperature isomerization process can provide highoctane isomerate. The once-through process can produce isomerate with RON 83. Whereas, the octane number of medium-temperature isomerization process is only about 78. The low-temperature process requires more severe reaction environment. The paper also provides an introduction and comparison of several isomerization processes which recycle part of low-octane products to reactor for high-octane isomerate production. Low-temperature isomerization process with isohexane and normal hexane recycles, whose RON can reach about 88, is more economical and commonly applied in China. The clients can select appropriate isomerization process and recycle process flow according to their actual requirements.

Hu M.,Luoyang Petrochemical Engineering Corporation | Liu W.,CPECC
Petroleum Refinery Engineering | Year: 2013

The understanding of coking has been deepened through the analysis of the causes of coking in FCCU settler. It is concluded by the author that the main precursors of coke are the unevaporized and unconverted heavy oil component in reactor oil vapor and "soft coke" from stripping section. The following countermeasures are proposed to control and mitigate the coking in the settler: the design of feed atomizing system and riser reactor is optimized to eliminate the " liquid mist formation zone": the temperature of catalysts is reduced before they contact with oil and appropriate temperature of catalyst is above 630 °C: advanced catalyst and oil mixing technology is applied to realize the operation of " large catalyst to oil ratio, strong back mixing and short contact time": The reaction depth is properly controlled and slurry is not recycled when its density (20 °C) is greater than 1 050 kg/m so as to lower the slurry in reactor oil vapor: 500 °C operating temperature is recommended for stripping section to further promote the conversion of heavy hydrocarbons carried over with the spent catalysts. The taking of above measures can inhibit and mitigate the coking in FCCU settler.

Zhang X.-G.,CPECC | Qiu M.-T.,CPECC | Luo C.-R.,CPECC
Petrochemical Equipment | Year: 2015

Due to the dry-wet interface at the entrance segment of residue fluid catalytic cracking unit (RFCCU) flue gas scrubber, it is important to select suitable material for such a corrosive and abrasive condition Alloy 20 is widely applied in RFCCU flue gas scrubber because of its excellent performance and relatively low price. Chemical composition, mechanical properties, physical and technological properties of Alloy 20 are introduced. Besides,welding techniques to reduce hot cracking,intercrystalline corrosion and stress corrosion cracking are also introduced.

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