Liquid Ammonia Injection for Biuret Control in Urea Plants
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Solution Overview
Problem
Modern urea production plants face challenges in controlling biuret formation, especially when operating at reduced capacity, and existing methods are costly to implement in existing plants.
Innovation Solution
Adding liquid ammonia to the urea aqueous stream downstream of the recovery section, allowing sufficient residence time and adjusting temperature, shifts the chemical equilibrium to reduce biuret formation, which can be done in any urea plant with an ammonia abatement section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If modern urea production plants operate at reduced capacity, then production flexibility is improved, but biuret formation increases making it difficult to meet quality specifications
Solution Approach 1:
The invention changes the chemical parameters by adding liquid ammonia to the urea aqueous stream, which shifts the chemical equilibrium and reduces biuret formation. This allows the plant to operate at reduced capacity while still meeting biuret specifications, resolving the contradiction between production flexibility and biuret content control.
2Manufacturing precision
If existing methods to control biuret formation are implemented in existing plants, then biuret content is reduced, but implementation cost increases significantly
Solution Approach 1:
The invention uses the existing ammonia abatement section infrastructure to serve a dual purpose: continuing its ammonia removal function while also providing liquid ammonia to the urea aqueous stream to control biuret formation. This self-service approach reduces implementation costs by utilizing existing plant equipment rather than requiring entirely new systems.
3Manufacturing precision
If liquid ammonia is added to urea aqueous stream to reduce biuret formation, then biuret content is controlled, but ammonia emissions increase requiring abatement infrastructure
Solution Approach 1:
The invention converts the potentially harmful effect of increased ammonia emissions into a benefit by utilizing the existing ammonia abatement section. The additional ammonia introduced to control biuret is subsequently removed by the abatement infrastructure, transforming what would be an environmental problem into a controllable process parameter that achieves dual objectives.
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
Effectively controls biuret formation across various operating capacities without significant modifications to existing plants, ensuring urea quality meets specifications for different applications.
Implementation Method 1
Adding liquid ammonia to the urea aqueous stream downstream of the recovery section, allowing sufficient residence time and adjusting temperature, shifts the chemical equilibrium to reduce biuret formation
Data Source
AI summary
Disclosed is a novel method of controlling the formation of biuret in urea production, and particularly reducing, preventing or reversing such formation. This is accomplished by adding liquid ammonia to a urea aqueous stream. This addition is done at one or more positions downstream of a recovery section in a urea plant. The addition of liquid ammonia serves to shift the equilibrium of biuret formation from urea, to the side of the formation of urea from biuret and ammonia. The invention can be accomplished also in pre-existing urea plant, by the simple measure of providing an appropriate inlet for liquid ammonia, in fluid communication with a source of such liquid ammonia.