Bio-oil Hydroprocessing Reactor Temperature Control via Feed Segmentation
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Solution Overview
Problem
Conventional methods for deoxygenation of bio-oils and fatty acid derivatives in commercial reactors face challenges with localized heat release, leading to temperature increases and potential catalyst bed and reactor integrity issues, necessitating substantial product recycle and increased reactor size.
Innovation Solution
The method involves exposing a limited portion of the feedstock to the initial hydroprocessing catalyst bed, followed by cooling and subsequent processing through additional catalyst beds, using techniques such as hydrogen quench streams or heat exchangers to manage temperature and reduce product recycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If deoxygenation is performed on feeds containing bio-oils, fatty acids, and/or fatty acid derivatives in a commercial scale reactor, then oxygen is removed from the feed, but localized heat release occurs leading to temperature increases that can damage catalyst beds and reactor structure
Solution Approach 1:
The patent divides the feedstock processing into multiple catalyst beds arranged in series, with each bed handling a portion of the deoxygenation reaction. This segmentation distributes the heat release across multiple zones rather than concentrating it in a single location, preventing localized temperature spikes that would damage catalyst or reactor structure.
Solution Approach 2:
The patent introduces a recycle stream of already-deoxygenated product that acts as a thermal buffer or intermediary. This recycle stream absorbs excess heat from the deoxygenation reaction, preventing localized temperature increases while still allowing the reaction to proceed. The recycle stream effectively mediates between the exothermic reaction and the reactor components.
2Temperature
If substantial product recycle is used to manage heat release, then localized temperature increases are reduced, but reactor size and support component size are substantially increased
Solution Approach 1:
By segmenting the reactor into multiple catalyst beds, the patent reduces the amount of recycle stream needed compared to a single-bed reactor. Each bed handles a smaller portion of the total deoxygenation load, allowing for more efficient heat management with reduced recycle ratios, thereby minimizing the additional volume required.
Solution Approach 2:
The patent optimizes operating parameters such as temperature, pressure, and space velocity across different catalyst beds to maximize reaction efficiency. By carefully controlling these parameters, the process achieves effective heat management with minimal recycle, reducing the overall reactor volume required compared to conventional single-bed designs.
3Temperature
If multiple catalyst beds are used to process feedstock, then heat release is distributed and temperature control is improved, but device complexity increases
Solution Approach 1:
The patent uses multiple catalyst beds with different functionalities arranged in a logical sequence. Each bed is optimized for specific reactions (e.g., hydrodeoxygenation, hydrodesulfurization, hydrodenitrogenation), allowing complex chemical transformations to occur in a structured, manageable way that simplifies overall process design and operation.
Solution Approach 2:
The recycle stream serves multiple functions simultaneously: it acts as a thermal buffer to control temperature, provides additional residence time for incomplete reactions, and helps maintain catalyst activity. This multi-functionality reduces the need for separate dedicated systems, thereby reducing overall device complexity despite using multiple catalyst beds.
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 effectively manages the heat release during hydrodeoxygenation, maintaining a target temperature profile across the reactor and reducing the need for product recycle, thereby optimizing reactor design and operation.
Implementation Method 1
exposing a first portion of a feedstock comprising 1.0 wt % or more of oxygen to a first hydroprocessing catalyst in a first catalyst bed in the presence of a hydrogen-containing treat gas under first hydroprocessing conditions to form a first liquid product effluent comprising 0.5 wt % or less of oxygen
Implementation Method 2
cooling at least a portion of the first liquid product effluent
Data Source
AI summary
Systems and methods are provided for hydroprocessing of bio-derived feeds, such as bio-oils and/or other types of feeds including triglycerides, fatty acids, and/or fatty acid derivatives. The systems and methods can assist with maintaining a desired temperature profile within a reactor while performing hydroprocessing on a feed with substantial oxygen content. In various aspects, the initial bed of the reactor can be exposed to 30 vol % or less of the total fresh feed. The remaining portions of the fresh feed can be introduced below one or more of the catalyst beds in the reactor. By reducing or minimizing the amount of fresh feed introduced upstream from the initial catalyst bed that contains a catalyst with hydrodeoxygenation activity, the net amount of product recycle can be reduced or minimized while still maintaining a target temperature profile across individual catalyst beds and/or across the reactor.