Methanol Urea Co-Production via Stoichiometric Reforming
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Solution Overview
Problem
Current processes for co-producing methanol and urea from hydrocarbon feeds result in excessive production of carbon dioxide and hydrogen, which are not efficiently utilized, leading to environmental emissions.
Innovation Solution
A sequential and once-through process involving primary and secondary reforming, partial water gas shift, catalytic conversion, and recycling of carbon dioxide to produce synthesis gas with a stoichiometric composition, allowing for efficient production of methanol and urea with minimal excess emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional co-production processes are used to produce methanol and urea from hydrocarbon feeds, then methanol and urea can be produced, but excessive carbon dioxide and hydrogen are generated as waste products
Solution Approach 1:
The invention changes the operational parameters of the reforming process by introducing oxygen-enriched air in the secondary reforming stage and adjusting steam-to-hydrocarbon ratios in the primary reforming stage. These parameter changes enable stoichiometric synthesis gas production with minimal excess carbon dioxide and hydrogen, resolving the contradiction between productive output and harmful emissions.
Solution Approach 2:
The invention implements a feedback mechanism by recycling a portion of the carbon dioxide produced during the process back to the primary reforming stage as a reactant. This feedback loop ensures that carbon dioxide is not wasted but rather reused to maintain stoichiometric balance in the synthesis gas, thereby reducing net emissions while maintaining productivity.
2Object-generated harmful factors
If stoichiometric synthesis gas is produced through optimized reforming, then carbon dioxide and hydrogen emissions are reduced, but the process complexity increases
Solution Approach 1:
The invention segments the reforming process into two distinct stages: primary reforming with steam and carbon dioxide, and secondary reforming with oxygen-enriched air. This segmentation allows each stage to be optimized independently for specific functions, managing overall process complexity while achieving stoichiometric synthesis gas production with reduced emissions.
Solution Approach 2:
The invention introduces oxygen-enriched air as an intermediary substance in the secondary reforming stage. This intermediary enables controlled oxidation and heat transfer while maintaining stoichiometric balance. The oxygen-enriched air acts as a mediator between the hydrocarbon feed and the final synthesis gas, facilitating emissions reduction without requiring overly complex process integration.
3Manufacturing precision
If carbon dioxide is recycled to the primary reforming stage, then synthesis gas composition is optimized, but equipment requirements and operational difficulty increase
Solution Approach 1:
The primary reforming unit is designed with multi-functionality, serving both as a steam reforming reactor and a carbon dioxide utilization reactor. By making the equipment universal, the process can handle both steam and carbon dioxide as reactants in the same unit, optimizing synthesis gas composition while avoiding the need for separate equipment and simplifying operational procedures.
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
The process significantly reduces carbon dioxide and hydrogen emissions by optimizing the molar ratios of synthesis gas components, ensuring that all produced carbon monoxide and hydrogen are used in methanol and urea synthesis, with minimal venting and efficient recycling, thereby enhancing environmental sustainability and reducing equipment costs.
Implementation Method 1
catalytically converting the carbon monoxide, carbon dioxide and hydrogen of the synthesis gas from step (c) in a once-through methanol synthesis stage
Implementation Method 2
subjecting the gaseous effluent from step (d) to catalytic methanation to remove the unconverted carbon monoxide and carbon dioxide
Implementation Method 3
catalytically converting the nitrogen and hydrogen in the gaseous effluent from step (e) in an ammonia synthesis stage
Implementation Method 4
converting the ammonia in the effluent to urea product by reaction with at least part of the carbon dioxide being removed from the synthesis gas in step (c)
Implementation Method 5
producing a synthesis gas containing hydrogen, carbon monoxide and dioxide and nitrogen by steam reforming the hydrocarbon feedstock in a primary reforming stage
Implementation Method 6
removing at least part of the carbon dioxide from the synthesis gas from step (b)
Data Source
AI summary
Process for the co-production of methanol and urea from a hydrocarbon feed without venting large amounts of carbon dioxide to the atmosphere.