Granular Urea Fluidized Bed Drying Process
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Solution Overview
Problem
Existing granular urea production methods using fluidized beds face challenges in achieving low moisture content, leading to increased energy consumption, product hardness issues, and agglomeration problems, especially when using aqueous urea solutions with concentrations below 95 wt%, which require additional concentrating systems and result in higher production costs.
Innovation Solution
A process involving a fluidized bed or spouted bed granulation method where an aqueous urea solution with a concentration of 94-98.5 wt% is granulated at an operation temperature of 110-120°C, utilizing an air-supplying pipe and nozzle for efficient drying, and a porous plate for fluidizing air, to achieve a granular urea product with moisture content of 0.3 wt% or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aqueous urea solution with concentration below 95 wt% is used for granulation, then production cost is reduced by avoiding additional concentrating systems, but moisture content in the granular product increases leading to product hardness issues and agglomeration
Solution Approach 1:
The invention changes the operational parameters of the fluidized bed granulator, specifically operating at a temperature range of 80-100°C and controlling the residence time of granules in the bed, to achieve consistent moisture content of 0.3 wt% or less while using aqueous urea solutions with concentrations of 94-98.5 wt%, thereby avoiding the need for additional concentrating systems
Solution Approach 2:
The invention replaces the conventional mechanical drying systems or vacuum concentrating systems with a thermally-controlled fluidized bed granulation process that achieves both granulation and moisture removal in a single integrated operation, eliminating the need for separate concentrating equipment
2Device complexity
If conventional fluidized bed granulation is used without optimized temperature control, then granulation process is simplified, but moisture content in product remains high requiring additional drying steps and increasing energy consumption
Solution Approach 1:
The invention merges the granulation process and the drying process into a single integrated fluidized bed operation, where granules are formed and simultaneously dried to the desired moisture content of 0.3 wt% or less, eliminating the need for separate drying equipment and reducing overall energy consumption
3Manufacturing precision
If higher temperature is used to reduce moisture content in granular urea, then product hardness is improved, but energy consumption increases and risk of urea decomposition rises
Solution Approach 1:
The invention optimizes the temperature parameter within a specific range of 80-100°C during fluidized bed granulation, which is sufficient to achieve moisture content of 0.3 wt% or less and ensure product hardness without excessive energy consumption or risk of urea decomposition that would occur at higher temperatures
4Ease of manufacture
If aqueous urea solution with lower concentration is used to avoid concentrating systems, then production cost is reduced, but additional equipment for fluidization control is required
Solution Approach 1:
The fluidized bed granulator is designed to perform multiple functions: it serves as both the granulation reactor and the drying chamber, while also functioning as the fluidization control system through its air distribution design, thereby achieving complex process control without requiring additional specialized equipment
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 method consistently produces granular urea with low moisture content, enhancing product hardness and reducing dust generation, while maintaining high production efficiency and minimizing energy consumption.
Implementation Method 1
granulating processes employing a fluidized bed or a fluidized, spouted bed become mainstream
Implementation Method 2
Moisture of the granular urea prepared by the method is described as 0.3 wt% or less without specific value
Implementation Method 3
crystallizes urea on the nuclei to form a granulated product
Data Source
Figure 1~2
AI summary
To effectively prepare granular urea that constantly has a moisture concentration of 0.3 wt% or less in the product and has a large grain load strength to be hardly crashed. In a granulating process for preparing granular urea from an aqueous urea solution using a fluidized bed method or a fluidized, spouted bed method, an aqueous urea solution having an urea concentration of 94-98.5 wt% is used, and an operation temperature of the fluidized bed is controlled in a range of 110-120°C to accelerate drying of a granulated product, thereby giving a granular urea product having moisture of 0.3 wt% or less in the product.