Cold Wall Ammonia Synthesis Reactor Metallurgical Cost Reduction
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Solution Overview
Problem
Conventional exothermic ammonia synthesis reactors require thick, high-alloy metal components to withstand high temperatures and pressures, leading to increased costs due to metallurgical demands.
Innovation Solution
A cold wall synthesis reactor design where an inner shell with catalyst beds is housed within an outer shell, with a cooling fluid circulating between them to maintain the outer shell at a lower temperature, reducing the need for high-alloy metals in the outer shell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional exothermic synthesis reactors are used with catalyst beds in a basket, then ammonia synthesis can proceed, but the outer pressure shell and basket require thick high-alloy metal components to withstand high temperatures and pressures, increasing costs
Solution Approach 1:
The reactor is divided into an inner pressure shell containing the catalyst basket and an outer pressure shell. The inner shell is directly exposed to reaction conditions and uses high-alloy materials, while the outer shell is cooled and uses lower-alloy materials, segmenting the thermal exposure zones to reduce overall metallurgical requirements
Solution Approach 2:
A cooling medium flows through the annular space between the inner and outer pressure shells, acting as an intermediary that absorbs heat from the inner shell and transports it away, thereby protecting the outer shell from direct thermal exposure and reducing its metallurgical requirements
2Use of energy by moving object
If the outer pressure shell is cooled by flowing feed gas through the annular space, then feed gas is preheated, but the outer shell is still exposed to significant heat and pressure requiring high-alloy materials
Solution Approach 1:
A dedicated cooling medium is introduced as an intermediary between the inner reaction zone and the outer shell, absorbing heat more effectively than feed gas alone and maintaining the outer shell at lower temperatures, thereby reducing metallurgical requirements while still allowing feed gas preheating to occur
Solution Approach 2:
The cooling approach is changed from using only feed gas (single fluid) to using a separate cooling medium circulating through the annular space (dual fluid system), changing the thermal management parameters to maintain lower outer shell temperatures and reduce alloy requirements
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 design lowers the metallurgical requirements and costs by maintaining the outer shell at a lower temperature, while maintaining the inner shell and reaction zone at optimal temperatures for ammonia synthesis, enhancing operational efficiency and reducing material expenses.
Implementation Method 1
A cooling fluid is provided to the outer shell such that the cooling fluid flows through at least a portion of the space and is in fluid communication with the exterior of the inner shell
Implementation Method 2
The heats and pressures generated by the exothermic synthesis in the annular space between the basket and the outer pressure shell are significant
Implementation Method 3
The heat transferred to the feed gas from the exothermic reaction occurring in the basket preheats the feed gas to the required reaction temperature
Data Source
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AI summary
Systems and methods for producing ammonia. Nitrogen and hydrogen can be supplied to a reaction zone disposed inside an inner shell. The inner shell can be disposed inside an outer shell such that a space is formed therebetween. The reaction zone can include at least one catalyst bed in indirect heat exchange with the space. The nitrogen and hydrogen can be reacted in the reaction zone in the presence of at least one catalyst to form an effluent comprising ammonia. The effluent can be recovered from the inner shell and cooled to provide a cooled effluent stream. A cooling fluid can be provided to the outer shell such that the cooling fluid flows through at least a portion of the space and is in fluid communication with the exterior of the inner shell. At least a portion of the cooled effluent can provide at least a portion of the cooling fluid. The cooling fluid can then be recovered from the outer shell as an ammonia product.