What are the advantages and disadvantages of the rotational separation mode in catalytic settlers?
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The main types of swirl separation in catalytic settlers are as follows: 1. Single swirl + rough swirl: There are two connection types – soft connection and quasi-connection. The soft connection can reduce the residence time of oil and gas; what are its disadvantages? Quasi-connection: Offers high operational flexibility, but the oil and gas stay for a long time, making coking more likely. 2. Fast separation + single selection: 3. VQS: Advantages: Short residence time for oil and gas, which helps prevent coking. Disadvantages: Limited operational flexibility, and there is a tendency for leakage of the fluid. To address this issue, balance tubes were added as improvements, but they still cannot provide sufficient operational flexibility. It is reported that a large catalytic unit had to shut down due to fluid leakage from its settler; VQS was used in that unit, but the exact cause remains to be determined. That’s about all I know; feel free to add your thoughts and discuss further
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We have relatively mature technologies for coarse spinning and single spinning. For our new projects, the original design involved flexible connections, which seemed unsafe; therefore those flexible connections were removed, and the outlet of the coarse spinning air lift pipe was changed to a grid format. The performance is acceptable, but the problem of coking in the settler is quite severe. This is because the thick swirls and single swirls are not directly connected; a portion of the oil and gas separated from the thick swirls stays in the settler for a longer period of time, increasing the tendency to form coking. But this format offers greater operational flexibility. If soft connections are used, the operational risks are high; especially when there are significant changes in operating conditions, resulting in a decrease in the efficiency of the coarse spinning process, or when the single-spinning material leg becomes blocked, a large amount of catalyst will flow into the distillation tower, rendering the slurry system completely unusable. The other two forms have not been used in practice; I hope those who are currently using them will share their insights. It is best to include diagrams, as it makes learning more intuitive.