| Fluid catalytic cracking process is a main method of converting the heavy hydrocarbon molecules into lighter molecules in petroleum refining industry.The existence of multiple steady states in fluid catalytic cracking units has a major impact in the supervision of these systems.In terms of economic or the processing capacity and unit scale,research on multi-stable properties have a very important practical significance.The catalytic cracking related research progress and results are reviewed in this paper, and then take the reactor and regenerator system in FCCU based on standard pseudo-component as the research object, around the properties of multiple steady states, doing the following works:(1)Established reactor and regenerator system stable model:Firstly, established the riser model based on standard pseudo-component reaction kinetics and quasi-steady-state assumptions; secondly, established the regenerator model combined with coke combustion reaction kinetics, considered the existence of bypassing air and installed a heat exchanger on the regenerated catalyst stand pipe.(2)Tested the overall model by using the sequential module method as the solution strategy of the reactor-regenerator system, with the actual production data of a refinery.Then we analyze the steady-state characteristics of the system whit the yield of each oil product at the outlet of riser, the percentage of coke content on spent catalyst surface, the percentage of coke content on regenerated catalyst surface and the rario of carbon dioxide and carbon monoxide.(3)We get multiple sets of data from steady-state simulation, plot the heat curve with the regenerator temperature as x-axis and heat exchanger as y-axis, two steady states are found. In the operating range considered, the results show that it can influence the position of the steady states when change the catalyst oil ratio, combustion air temperature or feed temperature respectively, but the number of the steady states is unaffected. |
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