Renewable Fuel Hydroconversion via Selective Stripping and Isomerization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current processes for producing diesel and aviation fuels from renewable feedstocks, such as plant oils and animal fats, often result in fuels that meet diesel specifications but not aviation specifications, due to the production of straight-chain paraffins, and are inefficient in terms of hydrogen usage and catalyst performance, which is affected by oxygen-containing molecules.
Innovation Solution
A hydroconversion process involving hydrogenation, deoxygenation, isomerization, and selective hydrocracking, with a selective hot high-pressure hydrogen stripper to remove carbon oxides and improve catalyst performance, and the use of hydrocarbon recycle to increase hydrogen solubility and reduce operating pressure, allowing for the production of both diesel and aviation fuel range products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrogenation and deoxygenation are performed to produce diesel fuel from renewable feedstocks, then diesel specifications are met, but aviation fuel specifications are not met due to production of straight-chain paraffins
Solution Approach 1:
The process segments the production into distinct reaction zones: a first zone for hydrogenation and deoxygenation, and a second zone for hydroisomerization and hydrocracking. This segmentation allows different product specifications (diesel and aviation fuel) to be produced from the same feedstock by controlling which zone the effluent passes through or by adjusting operating parameters in each zone.
Solution Approach 2:
The patent employs parameter changes by adjusting temperature, pressure, and catalyst composition in different reaction zones to produce different fuel types. The first reaction zone operates under conditions optimized for hydrogenation and deoxygenation, while the second zone uses different parameters to enable isomerization and hydrocracking, thereby producing aviation fuel from the same renewable feedstock.
2Device complexity
If oxygen-containing molecules are present in the reaction mixture, then the process is simpler, but catalyst performance deteriorates due to deactivation
Solution Approach 1:
The patent applies preliminary action by removing oxygen-containing molecules (CO2, CO, H2O) from the reaction mixture before the effluent enters the second reaction zone containing the isomerization and hydrocracking catalyst. This preliminary removal prevents catalyst deactivation and maintains high catalyst performance throughout the process.
Solution Approach 2:
A selective hot high-pressure hydrogen stripper is introduced as an intermediary unit between the first and second reaction zones. This stripper selectively removes oxygen-containing molecules from the effluent of the first zone, protecting the catalyst in the second zone from deactivation while allowing the process to continue efficiently.
3Stress or pressure
If hydrocarbon recycle is used to increase hydrogen solubility, then operating pressure can be reduced, but device complexity increases
Solution Approach 1:
The hydrocarbon recycle stream serves multiple functions: it increases hydrogen solubility in the reaction mixture, acts as a heat transfer medium, and allows the process to operate at lower pressures. This multi-functionality reduces the need for additional specialized equipment while achieving multiple process objectives simultaneously.
Solution Approach 2:
The patent implements feedback by recycling a portion of the hydrocarbon product back to the reaction zones. This recycled hydrocarbon mixes with the feedstock and hydrogen, increasing hydrogen solubility and allowing the system to maintain efficient operation at reduced pressures. The feedback loop creates a self-regulating system that optimizes hydrogen utilization.
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 effectively produces diesel and aviation fuels with improved cold flow properties and reduced operating costs by increasing hydrogen solubility and minimizing catalyst deactivation, while meeting specific fuel specifications through selective hydrocracking and isomerization.
Implementation Method 1
treating the feedstock in a reaction zone by hydrogenating and deoxygenating the feedstock
Implementation Method 2
hydrodeoxygenation in at least a first zone
Implementation Method 3
A selective hot high pressure hydrogen stripper is used to remove at least the carbon oxides from the hydrogenation, decarboxylation and/or hydrodeoxygenation zone effluent
Implementation Method 4
hydroisomerization in at least a second zone
Implementation Method 5
selective hydrocracking a renewable feedstock in order to generate both a diesel range product and an aviation range product
Data Source
AI summary
A process has been developed for producing a diesel boiling point range product and an aviation boiling point range product from renewable feedstocks such as plant and animal oils. The process involves treating a renewable feedstock by hydrogenating and deoxygenating to provide a hydrocarbon fraction which is then isomerized and selectively cracked to form the diesel boiling point range product and the aviation boiling point range product. A portion of the diesel boiling point range product, aviation boiling point range product, naphtha product, LPG, or any combination thereof can be optionally used as a rectification agent in the selective hot high pressure hydrogen stripper to decrease the amount of product carried in the stripper overhead.