Upflow Hydrotreatment Reactor Hydrogen Distribution Plate
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Solution Overview
Problem
Existing upflow-type reactors used in hydrocarbon hydrotreatment have limited hydrogenation capacity, which restricts the hydroconversion of heavy oils and hydrocracking of vacuum distillates, leading to incomplete conversion and high operational complexity.
Innovation Solution
The method involves splitting the hydrogen flow at the base of the reactor and using distribution means with specific orifice spacing to increase the density of entry points, thereby expanding the hydrogen-hydrocarbon liquid interface and enhancing the hydrogenation rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hydrogen surface velocity is increased to expand the hydrogen-hydrocarbon liquid interface, then the hydrogenation rate improves, but the bubbles begin to coalesce forming larger diameter bubbles which reduces the contact surface
Solution Approach 1:
The distribution plate is segmented into multiple zones with different orifice diameters, creating a distribution of bubble sizes rather than a single uniform size. This segmentation prevents complete coalescence and maintains a larger total contact surface area while still allowing sufficient gas velocity for high hydrogenation rates.
Solution Approach 2:
Different regions of the distribution plate have different orifice sizes, creating local variations in bubble characteristics. Smaller orifices in certain zones generate smaller bubbles that resist coalescence, while larger orifices in other zones provide sufficient gas flow. This local quality variation optimizes both contact surface area and hydrogenation rate simultaneously.
2Productivity
If downflow reactors are used to achieve higher hydrogenation rates, then the hydrogenation capacity improves, but the operational complexity and need for vacuum distillation increases
Solution Approach 1:
Instead of using downflow reactors as conventionally done for high hydrogenation rates, this invention inverts the approach by using upflow reactors with optimized gas distribution. This reversal maintains the simplicity of upflow operation while achieving high hydrogenation rates through the segmented distribution plate, avoiding the complexity of downflow systems and vacuum distillation requirements.
3Quantity of substance
If the gas holdup is increased beyond 0.299 to maximize bubble packing, then the hydrogen concentration in liquid improves, but the bubbles coalesce which reduces the specific surface area
Solution Approach 1:
The segmented orifice design creates a polydisperse bubble population with various sizes throughout the reactor. Smaller bubbles from smaller orifices maintain high specific surface area even at elevated gas holdups, while the overall distribution allows sufficient hydrogen concentration in the liquid phase without complete coalescence.
Solution Approach 2:
By changing the distribution of orifice diameters rather than using a single size, the system can operate at higher gas holdups while maintaining adequate specific surface area. The parameter change from uniform to distributed orifice sizes allows simultaneous optimization of hydrogen concentration and contact surface area.
Data Source
AI summary
The hydrogenation capacity of an upflow hydrocarbon hydrotreatment reactor is increased by expanding the gas-liquid contact surface.