Liquid-full Hydroprocessing with Uneven Catalyst Volume Distribution
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Solution Overview
Problem
Conventional hydroprocessing processes for producing clean fuels are costly, inefficient, and result in catalyst deactivation due to uneven hydrogen distribution and coke formation, failing to achieve optimal sulfur and nitrogen conversion with high recycle ratios and inefficient heat removal.
Innovation Solution
A liquid-full hydroprocessing process with uneven catalyst volume distribution, where hydrogen is dissolved in a feed/diluent mixture and passed through multiple catalyst beds, allowing for improved hydrogen distribution and reduced recycle ratios, thereby enhancing sulfur and nitrogen conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional trickle bed reactors are used with three-phase flow, then hydrogen transfer from vapor phase through liquid phase to catalyst surface is achieved, but the system becomes expensive to operate, requires large quantities of hydrogen with high recycle ratios through expensive compressors, and has inefficient heat removal
Solution Approach 1:
The patent changes the physical state of hydrogen from vapor phase to dissolved liquid phase by adjusting process parameters (temperature, pressure, liquid-to-gas ratio). This allows hydrogen to be transported dissolved in the liquid hydrocarbon feed rather than as vapor, eliminating the need for expensive hydrogen compressors and reducing operating costs while maintaining effective hydrogen delivery to catalysts
Solution Approach 2:
The patent uses liquid-phase hydrogen transport (hydraulic principle) instead of gas-phase transport. Hydrogen is dissolved in the liquid feed stream and transported through the reactor beds in the liquid phase, replacing the conventional vapor-phase pneumatic transport system. This eliminates the need for high-pressure compressors and reduces energy consumption
2Loss of energy
If conventional trickle bed reactors are used, then hydroprocessing reaction is achieved, but heat removal from the highly exothermic process is inefficient
Solution Approach 1:
The patent uses liquid-phase flow (hydraulic principle) to remove heat from the reactor beds. The liquid hydrocarbon feed, which has high heat capacity, flows through the catalyst beds and efficiently carries away the exothermic heat of reaction. This liquid-cooling system is more effective than vapor-phase cooling, allowing higher reaction rates while maintaining temperature control
3Productivity
If conventional trickle bed reactors are used, then hydroprocessing reaction is achieved, but significant coke forms on catalyst surfaces causing catalyst deactivation
Solution Approach 1:
The patent changes the hydrogen delivery mechanism from vapor-phase contact to liquid-phase dissolved hydrogen. This parameter change results in more uniform hydrogen distribution throughout the liquid stream and more controlled hydrogen-catalyst interaction, reducing excessive hydrogenation reactions that lead to coke formation. The liquid-phase process maintains lower partial pressures of hydrogen at catalyst surfaces, preventing coke deposition while preserving sulfur and nitrogen conversion effectiveness
4Device complexity
If even catalyst volume distribution is used among multiple catalyst beds, then system simplicity is maintained, but hydrogen distribution is uneven and recycle ratio must be high
Solution Approach 1:
The patent applies local quality by varying the catalyst volume in different beds based on local process requirements. The first catalyst bed has a different catalyst volume than subsequent beds, optimizing hydrogen distribution along the flow path. This non-uniform distribution matches the decreasing hydrogen concentration along the reactor sequence, ensuring efficient hydrogen utilization without requiring high recycle ratios
Solution Approach 2:
The patent introduces asymmetry in catalyst bed volumes to correct the inherent asymmetry in hydrogen consumption along the flow path. By making the first bed have a different catalyst volume than subsequent beds, the system compensates for the progressive depletion of dissolved hydrogen, achieving more uniform hydrogen distribution and reducing the need for high recycle ratios
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
The process achieves sulfur and nitrogen conversion levels meeting Euro V specifications for ultra-low sulfur diesel, reduces catalyst deactivation, and minimizes hydrogen consumption, resulting in a more efficient and cost-effective hydroprocessing system.
Implementation Method 1
Hydrogen is dissolved in the feed/diluent mixture to provide hydrogen in the liquid phase
Implementation Method 2
contacting the feed/diluent/hydrogen mixture with a first catalyst in a first catalyst bed, to produce a product effluent
Implementation Method 3
Heat removal from the highly exothermic hydroprocessing processes is inefficient
Data Source
AI summary
The present invention provides a process for hydroprocessing hydrocarbons with uneven catalyst volume distribution among two or more catalyst beds. The process operates as a liquid-full process, wherein all of the hydrogen dissolves in the liquid phase. Hydrocarbons can be converted in the process to provide a liquid product including clean fuels with multiple desired properties such as low density and high cetane number.