Integrated Formaldehyde-Stabilised Urea Production Process
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Solution Overview
Problem
The existing processes for producing formaldehyde-stabilized urea often require separate facilities for formaldehyde production, leading to economic inefficiencies due to small-scale demand, and lack integration with ammonia and methanol co-production systems.
Innovation Solution
An integrated process that co-produces methanol and ammonia, including a dedicated formaldehyde stabilizer unit, where synthesis gas is processed through water-gas shift reactors, carbon dioxide removal, and methanol synthesis, with by-pass streams controlled to optimize carbon monoxide and carbon dioxide levels for flexible production and reduce the need for distillation steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If formaldehyde is produced at a separate dedicated facility, then formaldehyde can be produced in sufficient quantity, but capital costs and operating costs increase due to separate facilities and transportation
Solution Approach 1:
The patent combines the formaldehyde production unit with the ammonia and methanol production facilities into a single integrated plant. The formaldehyde is produced on-site from methanol oxidation, eliminating the need for separate dedicated formaldehyde production facilities and transportation infrastructure, while still meeting the required production quantity for urea stabilization
Solution Approach 2:
The methanol produced in the ammonia plant serves dual purposes: it is used as fuel/gas for the ammonia synthesis process and simultaneously as feedstock for formaldehyde production through oxidation. This multi-functional use of methanol reduces the need for separate production facilities
2Device complexity
If crude methanol is fed directly to oxidation reactor without distillation, then capital costs and operating costs decrease, but water content in crude methanol may affect oxidation efficiency
Solution Approach 1:
The oxidation reactor is designed to operate with crude methanol containing water, adjusting the oxidation parameters (temperature, catalyst, residence time) to accommodate the water content. This eliminates the need for distillation while maintaining oxidation efficiency through parameter optimization
Solution Approach 2:
The crude methanol from the methanol synthesis unit is used directly as feedstock for the oxidation reactor without requiring additional purification equipment. The system accepts the methanol as-is from the previous process unit, eliminating the distillation step and associated equipment
3Quantity of substance
If synthesis gas is processed through complete water-gas shift and CO2 removal, then CO and CO2 levels are reduced for methanol synthesis, but process complexity and capital costs increase
Solution Approach 1:
Instead of complete water-gas shift conversion, the patent uses partial shift conversion where only a portion of the synthesis gas is processed through the water-gas shift reactors. The by-pass streams allow control of CO and CO2 levels at the methanol synthesis unit without requiring complete conversion, reducing equipment complexity while maintaining sufficient reactant levels
4Adaptability or versatility
If by-pass streams are used to control CO and CO2 levels, then flexibility in production is improved, but process control complexity increases
Solution Approach 1:
The by-pass streams are designed with adjustable control valves that allow dynamic adjustment of the synthesis gas composition entering the methanol synthesis unit. This enables flexible control of CO and CO2 levels to optimize production rates and adapt to changing demand for methanol, ammonia, and formaldehyde
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 allows for increased flexibility in methanol, ammonia, and urea production, reduces capital and operating costs by eliminating the need for separate formaldehyde production facilities and distillation steps, and enhances the efficiency of the overall process.
Implementation Method 1
subjecting the synthesis gas 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 shifted gas in a carbon dioxide removal unit to form a carbon dioxide-depleted synthesis gas
Implementation Method 3
synthesising methanol from the carbon dioxide-depleted synthesis gas in a methanol synthesis unit
Implementation Method 4
subjecting at least a portion of the recovered methanol to oxidation with air in a formaldehyde production unit
Implementation Method 5
subjecting the methanol synthesis off-gas to methanation in a methanation reactor containing a methanation catalyst to form an ammonia synthesis gas
Data Source
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AI summary
A process for the production of formaldehyde-stabilised urea is described comprising the steps of: (a) generatinga synthesis gas comprising hydrogen, nitrogen, carbon monoxide, carbon dioxide and steam in a synthesis gas generation unit, (b) subjecting the synthesis gas to one or more stages of water-gas shift in one or more water-gas shift reactors to form a shifted gas; (c) recovering carbon dioxide from the shifted gas in a carbon dioxide removal unitto form a carbon dioxide-depleted synthesis gas; (d) synthesising methanol from the carbon dioxide-depleted synthesis gas in a methanol synthesis unit and recovering the methanol and a methanol synthesis off-gas comprising nitrogen, hydrogen and residual carbon monoxide; (e) subjecting at least a portion of the recovered methanol to oxidation with air in a formaldehyde production unit; (f) subjecting the methanol synthesis off-gas to methanation in a methanation reactor containing a methanation catalyst 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 recovered from the formaldehyde production unit, wherein a portion of the synthesis gas generated by the synthesis gas generation unitby-passes either the one or more water-gas shift reactors; the carbon dioxide removal unit; or the one or more water-gas shift reactors and the carbon dioxide removal unit.