Urea Concentration Biuret Control via Residence Time
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Solution Overview
Problem
Urea production plants, especially those operating at reduced capacity, face challenges in controlling biuret formation, which affects the quality of urea products and fails to meet desired biuret specifications.
Innovation Solution
The process involves controlling the residence time of the purified urea aqueous stream in the concentration section independently of the volume flow, achieved by configuring the plant to allow adjustable volume in the concentration section or by adding a gas, such as ammonia, to reduce the residence time and shift the chemical equilibrium, thereby minimizing biuret formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the plant operates at reduced capacity, then production flexibility is improved, but biuret formation increases and quality control deteriorates
Solution Approach 1:
The patent implements dynamic control of residence time in the concentration section by adjusting operational parameters (heating rate, temperature, pressure) based on the volume flow rate of the purified urea aqueous stream. This dynamic adjustment ensures that even at reduced capacity, the residence time remains optimized to prevent biuret formation, thereby maintaining manufacturing precision across varying production levels.
Solution Approach 2:
The patent changes physical parameters (temperature, pressure, heating rate) in the concentration section to control the residence time of the urea solution. By adjusting these parameters independently of volume flow, the system maintains optimal conditions for preventing biuret formation regardless of production capacity, thus resolving the contradiction between adaptability and manufacturing precision.
2Manufacturing precision
If the residence time in the concentration section is reduced, then biuret formation is minimized, but the independent control of residence time from volume flow becomes complex
Solution Approach 1:
The patent implements a feedback control system where the residence time in the concentration section is continuously monitored and adjusted based on the volume flow rate of the purified urea aqueous stream. This feedback mechanism automatically compensates for changes in production capacity, maintaining optimal residence time to minimize biuret formation without requiring complex manual intervention or sophisticated control systems.
3Productivity
If modern stripping technology is used, then production efficiency is improved, but biuret formation increases
Solution Approach 1:
The patent segments the concentration process into distinct operational zones with different heating rates and residence times. By dividing the concentration section into multiple stages, the system maintains high production efficiency while controlling the residence time in each stage to prevent biuret formation, thus resolving the contradiction between productivity and manufacturing precision.
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 effectively reduces biuret formation in urea products, ensuring they meet quality standards even when plants are not operating at full capacity, by decoupling residence time from volume flow and adjusting the chemical equilibrium in the concentration section.
Implementation Method 1
The downstream processing generally refers to one or more sections, zones, or units in which the aforementioned aqueous urea stream is further concentrated. Such further concentration is typically conducted by evaporation
Implementation Method 2
by adding a gas, such as ammonia, to reduce the residence time and shift the chemical equilibrium, thereby minimizing biuret formation
Data Source
AI summary
Disclosed is a novel method of controlling the formation of biuret in urea production. This is accomplished by reducing or preventing the formation of biuret in a concentration section, particularly in one or more concentrators or evaporators. The method comprises controlling the residence time of a urea aqueous stream treated in such concentration section in a manner independently of the volume flow per time interval of said stream into said concentration section. The residence time can be controlled, e.g., by providing the concentration section with an adjustable volume or by adding a gas to the urea stream to be treated. A combination of such measures can also be applied.