Isomerization Drier Regeneration Using Liquid Hydrocarbon Buffer
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Solution Overview
Problem
The isomerization of light paraffins in gasoline production is hindered by water as a catalyst poison, and the regeneration of driers with gas regenerants disrupts downstream operations by altering hydrogen:hydrocarbon ratios and causing flow and pressure control issues in distillation columns.
Innovation Solution
An apparatus and process that utilize a down-flow regenerant displacement assembly to gradually displace and remove used regenerants from drying zones, minimizing disruptions in downstream operations by using a dried reactant fluid to regulate the flow of regenerants from driers during regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If driers are regenerated with gas regenerant, then the drier is restored to drying condition, but the gas regenerant causes upsets in downstream vessels by altering hydrogen:hydrocarbon ratios and disrupting flow and pressure controls
Solution Approach 1:
A liquid hydrocarbon stream is introduced as an intermediary substance between the gas regenerant and the downstream reaction zone. The liquid stream acts as a buffer that absorbs the gas regenerant through vaporization, preventing direct contact between the gas regenerant and the hydrogen-rich gas stream. This intermediary approach allows the drier to be regenerated while protecting downstream operations from disruptions caused by the gas regenerant's heavier molecular weight and different properties.
2Duration of action of stationary object
If gas regenerant replaces hydrogen rich gas in the reactor, then the drier is regenerated, but the reaction temperature drops and the hydrogen:hydrocarbon mole ratio is disrupted
Solution Approach 1:
The liquid hydrocarbon stream is introduced upstream of the reaction zone, before the gas regenerant can reach the reactor. By preliminarily vaporizing the liquid stream in the drier outlet line, the system prepares a buffer that will absorb the gas regenerant before it can enter the reaction zone. This preliminary action prevents the temperature drop and mole ratio disruption that would occur if the gas regenerant directly replaced the hydrogen-rich gas in the reactor.
3Productivity
If two driers are used with alternating regeneration, then continuous drying operation is maintained, but the regenerant must be flushed out causing additional process upsets
Solution Approach 1:
The liquid hydrocarbon stream serves as a mediator that allows the regenerant to be removed without direct flushing into the downstream process. As the liquid vaporizes in the drier outlet line, it creates a vapor phase that absorbs the regenerant, enabling gentle removal rather than abrupt flushing. This maintains continuous drying capability while minimizing disruptions to downstream operations during the regenerant removal phase.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces upsets in downstream operations by gradually removing used regenerants, maintaining stable hydrogen:hydrocarbon ratios and flow controls, thus enhancing the efficiency and stability of the isomerization process.
Implementation Method 1
The liquid hydrocarbon stream can absorb water from the gas stream
Implementation Method 2
The liquid hydrocarbon stream can be vaporized to displace the gas regenerant from the drier
Data Source
AI summary
One exemplary embodiment can be an apparatus for isomerizing a hydrocarbon stream rich in a C4 hydrocarbon and/or at least one of a C5 and C6 hydrocarbon. The apparatus can include: a first drier and a second drier adapted to receive a fluid including at least one reactant; and a reaction zone communicating with the first drier to receive the fluid including at least one reactant and with the second drier to receive the regenerant. Generally, the first drier operates at a first condition to dry the fluid including at least one reactant and the second drier operates at a second condition during regeneration with a regenerant. The regenerant is displaced from the drier using a down-flow regenerant displacement assembly.