Batch Reactor Nitrogen Fertilizer Process Segmentation
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Solution Overview
Problem
Existing processes for producing liquid nitrogen fertilizer in batches result in unstable and non-transparent products with variable nitrogen release properties, particularly when using a single reaction step at elevated temperatures, which fails to maintain a high content of unreacted urea and controlled nitrogen characteristics.
Innovation Solution
A two-step process in a batch reactor where ammonia is added progressively to a urea-formaldehyde solution, controlling the temperature increase from 55°C to 80-95°C over 15 minutes, followed by maintaining the mixture at 80-100°C for at least 30 minutes, ensuring a controlled reaction and pH between 8 and 10.5, thereby minimizing high molecular weight polymerization and stabilizing the fertilizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a single reaction step at elevated temperatures (70-110°C for 10-30 minutes) is used to limit total reaction time and ensure high unreacted urea content, then the reaction time is reduced and urea content is maintained, but the fertilizer composition becomes unstable, non-transparent, and has variable nitrogen release properties
Solution Approach 1:
The single reaction step is divided into two distinct reaction steps: first reaction step at 70-90°C for 10-30 minutes to maintain high unreacted urea content, and second reaction step at 90-110°C for 10-30 minutes to ensure stability and transparency. This segmentation allows each step to optimize for its specific function, resolving the contradiction between speed and quality.
2Reliability
If the temperature is increased to 90-110°C to accelerate the reaction and improve transparency, then the reaction rate increases and composition stability improves, but the risk of excessive polymerization and loss of unreacted urea increases
Solution Approach 1:
The temperature profile is segmented into two stages: the first reaction step uses moderate temperature (70-90°C) to preserve unreacted urea, while the second reaction step uses higher temperature (90-110°C) to ensure stability and transparency. This temporal separation of temperature conditions allows both contradictory requirements to be satisfied at different times.
Solution Approach 2:
The first reaction step performs preliminary action by establishing the high unreacted urea content before the second reaction step modifies the composition for stability. This preliminary establishment of urea content prevents its loss during the subsequent high-temperature step.
3Productivity
If ammonia is added quickly to reduce processing time, then the productivity increases, but the temperature control becomes difficult and local overheating occurs leading to uncontrolled polymerization
Solution Approach 1:
The ammonia addition process is segmented into two phases corresponding to the two reaction steps, with controlled addition rates in each phase. This segmentation allows the exothermic reaction to be managed in stages, preventing runaway polymerization while maintaining productivity.
Solution Approach 2:
The two reaction steps are performed continuously without interruption, with the second step immediately following the first. This continuous process maintains productivity while the staged temperature control prevents local overheating and uncontrolled polymerization.
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 produces a stable, transparent liquid nitrogen fertilizer with reliable nitrogen release properties, achieving 50-75% of nitrogen as methylene-urea and 30-45% as ureic nitrogen, while maintaining stability and controlling exothermic reactions to prevent local overheating.
Implementation Method 1
adding progressively during at least 15 minutes an ammonia aqueous solution (with an ammonia content of 20 to 32% by weight) to a formaldehyde - urea solution so as to control the progressive increase of temperature of the reaction medium up to 80 - 95°C
Data Source
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AI summary
Process for the preparation in a batch reactor of at least 10 Tons of a liquid nitrogen fertilizer with a nitrogen weight content from 20 to 32%, said process comprising at least the step of adding progressively during at least 15 minutes an ammonia solution to a formaldehyde - urea solution so as to control the progressive increase of temperature of the reaction medium up to 80 - 95°C.