Hydrocarbon Separation Unit with Reflux for Impurity Removal
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Solution Overview
Problem
Existing processes for producing hydrocarbons, such as jet fuel, from renewable and fossil sources face challenges in reducing impurities like H2S, H2O, NH3, and CO2, which can contaminate noble metal catalysts used in the dewaxing step, particularly when using feedstocks from renewable sources.
Innovation Solution
A process involving a hydroprocessing step followed by a separation unit with reflux, where the overhead hydrocarbon liquid stream is used as reflux to the separation unit, significantly reducing impurities like H2S and H2O before the dewaxing step, and a single hydrogen recycle loop is used to integrate and simplify the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overhead hydrocarbon liquid stream is sent directly to the dewaxing step, then the process is simple and continuous, but the noble metal catalysts are contaminated and impaired by impurities such as H2S, H2O, NH3, CO and CO2
Solution Approach 1:
The invention applies preliminary action by introducing a separation unit before the dewaxing step to remove impurities (H2S, H2O, NH3, CO, CO2) from the hydrocarbon liquid stream. This preliminary separation prevents catalyst contamination before the catalytic reaction occurs, thereby protecting catalyst performance without requiring complex modifications to the dewaxing unit itself.
Solution Approach 2:
The separation unit acts as an intermediary between the hydroprocessing step and the dewaxing step. It mediates the transition by selectively removing harmful impurities while allowing hydrocarbons to pass through, thus protecting the noble metal catalysts from direct contact with contaminants without disrupting the overall process flow.
2Reliability
If a separation unit with reflux is introduced to remove impurities, then catalyst protection is improved, but the device complexity and energy consumption increase
Solution Approach 1:
The separation unit utilizes phase transitions (condensation and vaporization) to achieve impurity removal. The reflux mechanism relies on condensing vapor phases and returning liquid to the separation unit, leveraging natural phase change thermodynamics to enhance separation efficiency while minimizing additional energy input requirements compared to purely thermal separation methods.
3Manufacturing precision
If multiple separation steps are used to reduce impurities, then manufacturing precision is improved, but productivity decreases due to additional processing time
Solution Approach 1:
The invention segments the impurity removal function into a dedicated separation unit with specific reflux mechanisms, rather than attempting to achieve separation through multiple sequential distillation columns or repeated processing steps. This segmentation allows for optimized single-stage separation that maintains high impurity removal efficiency while minimizing residence time and processing delays.
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 results in a substantial reduction of impurities by one order of magnitude, effectively protecting the noble metal catalysts and ensuring the production of high-quality hydrocarbon products like jet fuel and diesel by minimizing contamination.
Implementation Method 1
the overhead stream is partly condensed and the resulting hydrocarbon liquid fraction
Implementation Method 2
passing the feedstock through one or more catalytic hydrotreating units under the addition of hydrogen
Implementation Method 3
HDO to obtain a hydrotreated stream
Implementation Method 4
hydrodenitrification (HDN)
Implementation Method 5
in which hydroisomerization and possibly a side reaction of hydrocracking occurs
Data Source
AI summary
Process for producing a hydrocarbon product, said process comprising: i) passing a feedstock originating from a renewable source and/or from a fossil source through a hydroprocessing step for producing a main hydrotreated stream; said hydroprocessing step comprising: passing the feedstock through one or more catalytic hydrotreating units under the addition of hydrogen for producing a first hydrotreated stream; passing the first hydrotreated stream to a first separation step comprising the use of a separation unit for particularly removing the impurities H2S, CO, CO2 and H2O; withdrawing from said first separation step an overhead stream and separating an overhead hydrocarbon liquid stream thereof which is passed as a reflux stream to said first separation unit; withdrawing from said first separation step a bottom stream and passing at least a portion of said bottom stream to a dewaxing step comprising the use of one or more catalytic hydrotreating units under the addition of hydrogen for producing said main hydrotreated stream; and ii) passing the main hydrotreated stream to a second separation step for producing said hydrocarbon product.