Distillate Two-Phase Hydrogenation Reactor Design
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Solution Overview
Problem
The challenge lies in efficiently utilizing low-grade feedstock oil to produce diesel with ultralow sulfur content while minimizing the need for high hydrogen gas volumes and reducing the investment cost associated with circulating hydrogen compressors, as existing technologies face inefficiencies due to excessive hydrogen consumption and impurity accumulation in the hydrogenation process.
Innovation Solution
A distillate two-phase hydrogenation reactor with a specific structure that includes catalyst beds and an inner component for gas replenishment and stripping, allowing for the supplementation of hydrogen gas in the liquid phase and the removal of impurities like hydrogen sulfide and ammonia, thereby enhancing reaction efficiency and reducing the adverse effects of impurities on catalyst performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a large amount of hydrogen gas is used in the hydrogenation reaction, then the sulfur content in diesel fuel can be reduced to meet ultralow sulfur requirements, but the volume of hydrogen gas required becomes much greater than that consumed in the reaction, increasing equipment investment and operating costs
Solution Approach 1:
The patent changes the physical state parameter of hydrogen from gas phase to liquid phase by dissolving it in feedstock oil. This parameter change allows hydrogen to be delivered in a concentrated form (dissolved hydrogen concentration can reach several percent by volume) without requiring large volumes of gaseous hydrogen, thereby reducing the hydrogen-to-oil volume ratio from traditional 3:1 or higher to much lower values while still achieving ultralow sulfur content in diesel fuel
Solution Approach 2:
The patent introduces feedstock oil as an intermediary medium to carry dissolved hydrogen to the catalyst bed. Instead of directly introducing large volumes of hydrogen gas, the hydrogen is first dissolved in the feedstock oil, which then serves as the delivery vehicle. This intermediary approach enables efficient hydrogen transfer and reaction while minimizing the total volume of hydrogen required, reducing both equipment investment and operating costs
2Device complexity
If hydrogen gas is introduced into the liquid phase for hydrogenation reaction, then the reaction can proceed without circulating hydrogen compressor, but the solubility of hydrogen gas in liquid phase is limited, requiring large amounts of circulation oil or additional solvents which reduces hydrogenation efficiency
Solution Approach 1:
The patent applies parameter changes by increasing the pressure to enhance hydrogen solubility in the liquid phase. Under elevated pressure conditions, the solubility of hydrogen gas in feedstock oil increases significantly, allowing sufficient dissolved hydrogen to be available for the hydrogenation reaction without requiring large amounts of circulation oil or additional solvents, thus maintaining high hydrogenation efficiency while eliminating the need for circulating hydrogen compressor
Solution Approach 2:
The patent implements preliminary action by pre-dissolving hydrogen gas in the feedstock oil before introducing it to the catalyst bed. This pre-dissolution process ensures that the hydrogen is already in the appropriate concentration and state for efficient reaction, eliminating the need for subsequent circulation and re-transfer steps. The preliminary preparation of dissolved hydrogen mixture optimizes the reaction conditions from the outset, maintaining high productivity without complex circulation systems
3Reliability
If high hydrogen partial pressure is maintained to inhibit coke production and prolong catalyst life, then the hydrogenation reaction efficiency improves, but the required volume of hydrogen gas increases significantly
Solution Approach 1:
The patent changes the delivery form of hydrogen from gas phase to liquid phase (dissolved state), which allows maintaining the effective hydrogen partial pressure at the catalyst surface needed to inhibit coke production and prolong catalyst life, while delivering the hydrogen in a concentrated form that requires much smaller volumes. The dissolved hydrogen in feedstock oil provides sustained hydrogen supply at appropriate partial pressures without the volume penalties of gaseous hydrogen
Solution Approach 2:
The patent uses feedstock oil as an intermediary carrier to deliver hydrogen to the catalyst bed in a controlled manner. This intermediary system maintains stable hydrogen partial pressure at the catalyst surface throughout the reaction process, preventing coke formation and extending catalyst life. The liquid-phase delivery mechanism provides more uniform and sustained hydrogen supply compared to gas phase, optimizing catalyst performance while minimizing total hydrogen volume required
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 improves hydrogenation efficiency by optimizing hydrogen gas utilization, reducing impurity inhibition, and lowering equipment costs by eliminating the need for a circulating hydrogen compressor, while effectively producing clean diesel oil with reduced sulfur and nitrogen content.
Implementation Method 1
forming, after dissolving hydrogen, a saturated liquid-phase stream
Implementation Method 2
the inner component comprises a gas-liquid contact component and a stripping component
Implementation Method 3
an inner component for gas replenishment and for stripping a liquid-phase stream containing impurities
Implementation Method 4
the reaction between the dissolved hydrogen and sulfur compound occurs at an active centre of catalysts
Implementation Method 5
liquid-phase hydrogenation
Implementation Method 6
the hydrogenation reaction is a strong exothermic reaction, which, for controlling the reaction temperature, needs a large amount of hydrogen gas and feedstock oil to pass through catalyst beds to bring away reaction heat
Data Source
AI summary
A hydrogenation method and distillate two-phase hydrogenation reactor in which the size of an upper space of the reactor is greater than that of a lower catalyst bed part. The reactor comprises 2 to 4 catalyst beds. An inner component for gas replenishment and for stripping a liquid-phase stream containing impurities is arranged between at least one adjacent catalyst bed and comprises a separator plate and exhaust pipes. The separator plate is provided with multiple downcomer through holes. The separator plate is connected with a plurality of exhaust pipes. The exhaust pipes are vertically arranged above the separator plate. The top parts of the exhaust pipes are in contact with the lower part of the upper catalyst bed.