Pre-rise section of riser reactor
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What is the function of the pre-raising section in a riser reactor?
Perhaps it is to keep the flow state from the self-acting valve at the catalyst site to the riser in a stable and homogeneously distributed fluidized condition within the riser
It has two functions: one is to ensure that the catalyst can be fluidized within the lift pipe, and the other is to give the catalyst a certain flow velocity and induce turbulence before it comes into contact with the feedstock
The ideal flow pattern in a lift pipe is plug flow, but in practice it often deviates significantly from this ideal state. The pre-lift section is included to ensure a more uniform distribution of the catalyst, bringing the flow pattern closer to plug flow
It is a transition section that allows the catalyst to change from plug flow to piston flow, enabling full contact with the feed oil
It provides a preliminary fluidized state for the catalyst, enabling better flow within the riser
It is the catalyst that accelerates the process, ensuring thorough mixing with the oil; this prevents thermal cracking at high temperatures upon entry into the lift pipe, which could otherwise lead to the formation of excessive olefins and coking.