Integrated Formaldehyde-Stabilized Urea Production via Methanol Oxidation
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Solution Overview
Problem
The existing processes for producing formaldehyde-stabilized urea face challenges due to the small-scale demand for formaldehyde, which makes it economically unfeasible to have a dedicated formaldehyde stabilizer production facility, leading to increased transportation costs and inefficiencies in integrating methanol and ammonia co-production with formaldehyde synthesis.
Innovation Solution
An integrated process that co-produces methanol and ammonia, with a dedicated formaldehyde stabilizer unit, involving synthesis gas generation, water-gas shift, carbon dioxide removal, methanation, and methanol synthesis to produce formaldehyde, allowing for flexible production and reduced pressure drop across the ammonia plant, while utilizing a scrubber to remove contaminants and optimize catalyst performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If formaldehyde is produced at a separate dedicated facility and transported to the ammonia/urea production facility, then the formaldehyde stabilizer production can be carried out, but the transportation costs increase and efficiency decreases
Solution Approach 1:
The patent combines the formaldehyde stabilizer production unit with the ammonia/urea production facility into an integrated process. The synthesis gas generated at the ammonia/urea facility is directly used for methanol synthesis and subsequent formaldehyde production, eliminating the need for separate dedicated facilities and transportation. This merging of previously separate processes resolves the contradiction by achieving both production capability and elimination of transportation losses.
2Adaptability or versatility
If methanol synthesis is integrated with formaldehyde production, then flexibility in production amounts is improved, but pressure drop across the ammonia plant increases
Solution Approach 1:
The patent segments the synthesis gas flow into multiple streams: one stream proceeds to the ammonia production unit while another stream is directed to methanol synthesis and formaldehyde production. This segmentation allows independent control of each production pathway, providing flexibility in production amounts while preventing the methanol synthesis unit from creating excessive pressure drop across the entire ammonia plant by distributing the gas flow through separate pathways.
3Device complexity
If synthesis gas is used directly for methanol synthesis without contaminant removal, then the process is simplified, but catalyst poisoning occurs
Solution Approach 1:
The patent introduces a scrubber as an intermediary unit between synthesis gas generation and methanol synthesis. The scrubber removes contaminants such as ammonia and amine compounds from the synthesis gas before it enters the methanol synthesis unit, protecting the oxidation catalyst from poisoning. This intermediary step maintains catalyst reliability while the overall process remains relatively simple and integrated.
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 process enhances ammonia production efficiency, reduces catalyst poisoning risks, and provides flexibility in methanol and formaldehyde production, enabling cost-effective and efficient production of formaldehyde-stabilized urea by integrating methanol and ammonia co-production with formaldehyde synthesis.
Implementation Method 1
subjecting the first synthesis gas stream to one or more stages of water-gas shift in one or more water-gas shift reactors to form a shifted gas
Implementation Method 2
recovering carbon dioxide from the dried shifted gas in a carbon dioxide removal unit to form a carbon dioxide-depleted synthesis gas
Implementation Method 3
subjecting the carbon dioxide-depleted synthesis gas to a stage of methanation in one or more methanation reactors to form an ammonia synthesis gas
Implementation Method 4
synthesising ammonia from the ammonia synthesis gas in an ammonia production unit and recovering the ammonia
Implementation Method 5
reacting a portion of the ammonia and at least a portion of the recovered carbon dioxide stream in a urea production unit to form a urea stream
Implementation Method 6
subjecting at least a portion of the recovered methanol to oxidation with air in a formaldehyde stabiliser production unit to produce formaldehyde
Data Source
Figure 1
AI summary
An integrated process for the production of a formaldehyde-stabilised urea is described comprising the steps of: (a) generating a synthesis gas comprising hydrogen, nitrogen, carbon monoxide, carbon dioxide and steam in a synthesis gas generation unit; (b) dividing the synthesis gas into a first synthesis gas stream and a smaller second synthesis gas stream; (c) subjecting the first synthesis gas stream to one or more stages of water-gas shift in one or more water-gas shift reactors to form a shifted gas; (d) cooling the shifted gas to below the dew point and recovering condensate to form a dried shifted gas; (e) recovering carbon dioxide from the dried shifted gas in a carbon dioxide removal unit to form a carbon dioxide-depleted synthesis gas; (f) subjecting the carbon dioxide-depleted synthesis gas to a stage of methanation in one or more methanation reactors to form an ammonia synthesis gas; (g) synthesising ammonia from the ammonia synthesis gas in an ammonia production unit and recovering the ammonia; (h) reacting a portion of the ammonia and at least a portion of the recovered carbon dioxide stream in a urea production unit to form a urea stream; and (i) stabilising the urea by mixing the urea stream and a stabiliser prepared using formaldehyde to form a stabilised urea, wherein the formaldehyde is generated by steps comprising; (1) passing the second portion of synthesis gas through a scrubber to remove contaminants therefrom and form a scrubbed synthesis gas; (2) synthesising methanol from the scrubbed synthesis gas in a methanol synthesis unit, and recovering the methanol and a methanol synthesis off-gas; (3) combining the methanol synthesis off-gas with the shifted gas and (4) subjecting at least a portion of the recovered methanol to oxidation with air in a formaldehyde stabiliser production unit to produce formaldehyde.