Fluidized Bed Granulator With Inhomogeneous Sprayer Zones
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Solution Overview
Problem
Existing methods for producing dry urea or ammonium nitrate granules in fluidized bed reactors face challenges in reducing water content while minimizing energy consumption, as increasing residence time, atomizing solutions, or using concentrated solutions lead to higher energy demands.
Innovation Solution
A fluidized bed granulator with inhomogeneously distributed sprayers creates unsprayed zones where nuclei swirl and recycle, allowing for low water content granules with reduced energy consumption by optimizing sprayer placement and density, and using highly concentrated solutions with additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If residence time in the granulator is increased to produce drier granules, then water content is reduced, but power consumption increases due to higher fluidization air pressure
Solution Approach 1:
The sprayers are arranged to create zones with different spray densities - some areas receive intensive spraying while others receive little or no spray. This inhomogeneous distribution allows nuclei to be sprayed in certain zones while remaining unsprayed in others, creating a more efficient drying process that reduces both residence time and energy consumption
Solution Approach 2:
The alternating pattern of sprayed and unsprayed zones creates a periodic action where nuclei are repeatedly exposed to spray and then allowed to move through unsprayed zones. This periodic exposure to spraying followed by periods without spraying enhances water removal efficiency while reducing the mean residence time required
2Manufacturing precision
If urea solution is atomized to finer droplets to reduce water content, then water content is reduced, but power consumption increases due to higher air requirements
Solution Approach 1:
Instead of uniformly atomizing the entire urea solution, the system applies localized spraying only in specific zones where sprayers are positioned. The inhomogeneous distribution means that atomization occurs locally rather than globally, reducing the total air consumption and power requirements while still achieving effective water content reduction in the granules
3Manufacturing precision
If more concentrated urea solution is sprayed to achieve lower water content, then water content is reduced, but energy consumption increases due to reduced cooling effect requiring higher air flow speeds
Solution Approach 1:
The concentrated urea solution is sprayed locally in specific zones rather than uniformly throughout the granulator. This localized application of concentrated solution, combined with the inhomogeneous sprayer distribution, allows the system to achieve effective water content control while utilizing the natural cooling effect of water evaporation in the unsprayed zones, thereby reducing the need for high air flow speeds and associated energy consumption
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 achieves granules with water content below 0.3 wt% while maintaining low energy consumption by reducing mean residence time and fluidization air pressure, effectively addressing the challenge of producing dry granules without high energy expenditure.
Implementation Method 1
a fluidized bed granulator (1) includes one or more compartments with a floor with openings for the supply of a fluidization medium
Implementation Method 2
The sprayers are configured to spray the liquid in one or more spraying zones next to one or more unsprayed zones of the fluidized bed
Implementation Method 3
The water content of the granules produced with the granulator can be well below 0.3 wt % by total weight of the granules
Data Source
AI summary
A fluidized bed granulator comprising one or more compartments with a floor with openings for the supply of a fluidization medium and a plurality of sprayers. The sprayers are connected to a supply of a granulating liquid and are configured to spray the liquid in one or more spraying zones next to one or more unsprayed zones of the fluidized bed.