Single-Shell Open Interstage Reactor for Acrylic Acid Fouling Control
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Solution Overview
Problem
Commercial-scale acrylic acid production processes face challenges such as auto-oxidation of acrolein, organic fouling of intermediate conduits, high capital costs due to dual reactor vessels, and difficulties in removing accumulated solids from long reaction tubes, which limit productivity and yield.
Innovation Solution
A single-shell open interstage (SSOI) reactor design with integrated interstage heat exchanger and open interstage region, utilizing upflow or downflow operation, separate coolant control for each reaction stage, and inert materials to minimize fouling, along with supplemental oxidant supply and advanced monitoring systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If tandem reactors with two separate reaction vessels are used, then temperature control for each reaction stage is improved, but device complexity and capital cost increase
Solution Approach 1:
The single reaction vessel is segmented into two distinct reaction zones (first reaction zone with R1 catalyst and second reaction zone with R2 catalyst) separated by an interstage baffle. This allows independent temperature control for each zone through separate cooling systems while maintaining a simpler single-vessel configuration compared to tandem reactors.
2Productivity
If SRS reactors with long tubes are used, then productivity is improved, but difficulty in removing accumulated solids increases
Solution Approach 1:
The long reaction tubes are segmented into two sections by an interstage baffle with an open interstage region. This division allows solids to be removed more easily from the interstage region and prevents complete blockage of the entire tube, while still maintaining sufficient tube length for high productivity.
Solution Approach 2:
An open interstage region with inert packing material serves as an intermediary zone between the two reaction zones. This region facilitates easier removal of accumulated solids and provides a transition zone that maintains flow while allowing access for maintenance operations.
3Reliability
If intermediate conduits are used in tandem reactors, then auto-oxidation of acrolein is reduced, but organic fouling of the conduits occurs
Solution Approach 1:
The harmful intermediate conduit connecting two separate reaction vessels is eliminated by integrating both reaction zones within a single continuous reaction vessel. This removes the source of organic fouling in conduits while maintaining the benefits of staged reaction through the interstage baffle separation.
4Productivity
If R2 catalyst is used in the second reaction zone, then conversion of acrolein to acrylic acid is improved, but accumulation of molybdenum and carbonaceous materials occurs
Solution Approach 1:
The open interstage region with inert packing material serves as a zone where accumulated molybdenum and carbonaceous materials can be contained and managed. The inert packing provides surface area for material deposition while maintaining catalyst activity in the reaction zones, effectively converting the harmful accumulation into a manageable phenomenon.
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
Enhances productivity and yield by reducing fouling, allowing easy catalyst replacement, and enabling higher production rates while maintaining temperature control and reactant conversion efficiencies.
Implementation Method 1
coolant can be passed through the vessel shell to remove the heat of reaction
Implementation Method 2
Process gases may flow through the tubes, in direct contact with the catalyst particles, while coolant can be passed through the vessel shell to remove the heat of reaction
Implementation Method 3
R1 catalysts are mixed metal oxide ("MMO") catalysts generally comprising molybdenum, bismuth, and optionally iron, and are used to promote the conversion of propylene to acrolein
Implementation Method 4
the conversion of propylene to acrolein can be performed in the first reaction vessel
Implementation Method 5
R2 catalysts are also mixed metal oxide (MMO) catalysts, but these generally comprise molybdenum and vanadium, and are used to promote the conversion of acrolein to acrylic acid
Implementation Method 6
the conversion of acrolein to acrylic acid can be performed in the second reaction vessel
Data Source
Figure 1a
Figure 1b
Figure 1c~1e
AI summary
The present disclosure relates to a single shell open interstage reactor ("SSOI"). The SSOI comprises a first reaction stage, an interstage heat exchanger, an open interstage region, and a second reaction stage. The SSOI may be configured for upflow or downflow operation. Further, the open interstage region of the SSOI may comprise a supplemental oxidant feed. When the open interstage region comprises a supplemental oxidant feed, the SSOI may further comprise a supplemental oxidant mixing assembly. Processes for producing acrylic acid through the oxidation of propylene are also disclosed.