Parallel Water-Gas Shift Reactor for CO Conversion
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Solution Overview
Problem
The water gas shift reaction in industrial synthesis gas production struggles to effectively remove carbon monoxide, which acts as a catalyst poison, especially in ammonia synthesis, due to its strong exothermic nature causing equilibrium shifts and requiring multistage processes with high temperatures leading to incomplete conversion and catalyst inefficiency.
Innovation Solution
A process involving high-temperature and low-temperature CO conversion units arranged in parallel, where the synthesis gas stream is divided into substreams for separate low-temperature CO conversion, allowing for enhanced carbon monoxide removal and increased hydrogen yield, using specific catalysts like iron oxide and copper-based catalysts for each temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the water gas shift reaction is carried out at high temperatures, then the reaction rate increases, but the equilibrium is shifted toward reactants resulting in incomplete carbon monoxide conversion
Solution Approach 1:
The water gas shift process is divided into multiple stages with different temperature conditions. A first water gas shift unit operates at high temperature to provide high reaction rate, while a second water gas shift unit operates at low temperature to achieve complete carbon monoxide conversion. This segmentation allows each unit to optimize for its specific function, resolving the contradiction between reaction rate and conversion completeness.
Solution Approach 2:
The patent changes the temperature parameter between different reaction stages. The first unit uses high temperature (300-400°C) to maximize reaction rate, while the second unit uses low temperature (200-300°C) to favor product formation and achieve complete conversion. This parameter change allows the system to overcome the equilibrium limitation at high temperatures while maintaining high overall reaction rate.
2Manufacturing precision
If the water gas shift reaction is carried out at low temperatures, then the equilibrium favors reaction products achieving complete carbon monoxide conversion, but the reaction proceeds very slowly
Solution Approach 1:
The process is segmented into two functional units: the first unit handles high-temperature fast reaction, while the second unit handles low-temperature complete conversion. By segmenting the function, the system achieves both high reaction rate and complete conversion without requiring the entire process to operate at low temperature.
Solution Approach 2:
The first water gas shift unit performs preliminary conversion of carbon monoxide at high temperature to reduce its concentration significantly. This preliminary action prepares the gas stream for the second unit, where the reduced carbon monoxide concentration allows low-temperature operation to achieve complete conversion efficiently.
3Manufacturing precision
If multiple water gas shift stages with intermediate cooling are used, then complete carbon monoxide removal is achieved, but the device complexity increases
Solution Approach 1:
The system uses segmentation with two distinct water gas shift units operating at different temperatures. This simpler two-stage configuration achieves complete carbon monoxide removal without requiring complex multi-stage systems with multiple cooling intermediates, thus reducing device complexity while maintaining conversion completeness.
4Adaptability or versatility
If high temperature operation is used, then higher entry concentrations of carbon monoxide can be treated, but residual carbon monoxide remains in the product gas mixture
Solution Approach 1:
The first water gas shift unit is designed to handle high entry carbon monoxide concentrations at high temperature, providing robust performance for dirty gas streams. The second unit then polishes the output to achieve low exit carbon monoxide concentrations. This segmentation allows the system to adapt to various entry conditions while maintaining precise exit specifications.
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 significantly reduces carbon monoxide concentrations to below 0.8 mol%, optimizing hydrogen production and ammonia synthesis efficiency by minimizing catalyst usage and extending catalyst life, while reducing energy consumption and increasing ammonia production capacity.
Implementation Method 1
carbon monoxide is reacted with steam in the presence of a suitable catalyst to afford carbon dioxide and hydrogen
Implementation Method 2
in the presence of a suitable catalyst to afford carbon dioxide and hydrogen
Implementation Method 3
The conversion of carbon monoxide into carbon dioxide in the water gas shift reaction is strongly exothermic
Implementation Method 4
the reaction proceeds very slowly... Each temperature level has specialized catalysts which may differ markedly in their composition and in their operating range
Data Source
AI summary
A process for performing the water gas shift reaction wherein raw synthesis gas is reacted in the presence of steam and at least one water gas shift catalyst to convert carbon monoxide into carbon dioxide and to form hydrogen. The raw synthesis gas is initially passed through at least one unit for high-temperature CO conversion and subsequently, downstream thereof, passed through at least one unit for low-temperature CO conversion. After passing through the at least one unit for high-temperature CO conversion the synthesis gas stream is divided into at least two substreams. The first substream is passed through a first unit for low-temperature CO conversion and the second substream is passed through a second unit for low-temperature CO conversion, wherein both units for low-temperature CO conversion are arranged in parallel relative to one another.