Reverse Osmosis Purification for Low-Biuret Urea Production
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Solution Overview
Problem
Existing urea production processes struggle to efficiently and cost-effectively remove biuret impurities from aqueous urea solutions, particularly at partial loads, which affects the quality and efficiency of solid urea and SCR solutions, and requires expensive crystallization methods.
Innovation Solution
Implementing a reverse osmosis process using a semi-permeable membrane, specifically a thin-film composite membrane, to separate biuret from urea solutions by adjusting the pressure differential across the membrane, allowing for efficient biuret removal without significantly altering the water-to-urea ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If crystallization methods are used to remove biuret from urea solutions, then biuret removal efficiency is improved, but process complexity and cost increase significantly
Solution Approach 1:
The patent extracts biuret from the urea solution using a semi-permeable membrane in a reverse osmosis process. The membrane selectively allows water and urea to pass through while retaining biuret molecules, effectively separating the impurity without requiring complex crystallization equipment or multiple processing stages.
2Device complexity
If conventional filtration or evaporation methods are used, then process simplicity is maintained, but biuret removal efficiency is insufficient
Solution Approach 1:
The patent employs a semi-permeable membrane with specific pore characteristics that enable selective separation. The membrane's porous structure allows small molecules like water and urea to pass through while blocking larger biuret molecules, achieving efficient biuret removal through a simple single-stage process without complex equipment.
3Manufacturing precision
If pressure differential is increased to improve biuret removal, then separation efficiency improves, but energy consumption increases
Solution Approach 1:
The patent optimizes the pressure differential parameter to achieve the minimum effective pressure required for biuret separation. By carefully controlling this parameter and combining it with the selective properties of the semi-permeable membrane, the process achieves efficient biuret removal while minimizing energy consumption, avoiding excessive pressure application.
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 effectively reduces biuret content in urea solutions to meet stringent quality standards, such as 0.9% for solid urea and 0.3% for SCR solutions, while maintaining the water-to-urea ratio, and avoids the costs and complexities of crystallization, suitable for both full and partial plant loads.
Implementation Method 1
Implementing a reverse osmosis process using a semi-permeable membrane, specifically a thin-film composite membrane, to separate biuret from urea solutions
Implementation Method 2
separate biuret from the aqueous solution of water and urea by passing the solution through a semi-permeable membrane
Data Source
AI summary
A process for purifying a urea-containing aqueous stream, such as the aqueous stream from the recovery section of a urea plant, comprising a step of removing biuret from the urea-containing stream by reverse osmosis in one or more reverse osmosis stages.