Water-Absorbent Polymer Particle Production via Steam-Zoned Fluidized Bed
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Solution Overview
Problem
The existing processes for producing water-absorbent polymer particles by dropletization polymerization face challenges such as the formation of undesired lumps, high steam consumption, and residual monomers, which affect the quality and efficiency of the polymerization process.
Innovation Solution
A process involving polymerizing droplets of a monomer solution in a heated gas phase within a reactor with a gas distributor, reaction zone, and fluidized bed, where the gas is treated in a condenser column and recycled, maintaining a steam content of 0.05 to 0.3 kg steam per kg dry gas, and ensuring the steam content in the reaction zone is less than that in the fluidized bed, to optimize the polymerization conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high steam content is used in the reaction zone, then residual monomers are reduced, but lumps and undesired overs are formed
Solution Approach 1:
The patent applies local quality by maintaining different steam contents in different zones: low steam content (0.01-0.1 kg/kg) in the reaction zone to prevent lump formation, and high steam content (0.5-2.0 kg/kg) in the fluidized bed to reduce residual monomers. This spatial differentiation resolves the contradiction between particle quality and harmful byproducts.
Solution Approach 2:
The patent segments the gas flow path into distinct zones with different steam content requirements. The gas stream is separated into a reaction zone portion (low steam) and a fluidized bed portion (high steam), allowing each zone to operate under optimal conditions for its specific function without interfering with the other.
2Manufacturing precision
If high steam content is used in the fluidized bed, then residual monomers are reduced, but steam consumption increases
Solution Approach 1:
The patent implements feedback by recycling the gas stream from the fluidized bed back to the reaction zone, creating a closed-loop system. This allows the high-steam fluidized bed to operate efficiently for monomer removal while the recycled gas provides the necessary steam to the reaction zone without requiring additional external steam input.
Solution Approach 2:
The patent recovers and reuses the gas stream containing steam and unreacted monomers from the fluidized bed, directing it back to the reaction zone. This recovery approach eliminates waste steam and reduces overall energy consumption while maintaining the high steam content needed for effective monomer removal.
3Object-generated harmful factors
If low steam content is used in the reaction zone, then lump formation is prevented, but residual monomers increase
Solution Approach 1:
The patent segments the gas flow into distinct portions with different steam contents: low steam content (0.01-0.1 kg/kg) in the reaction zone to prevent lump formation during polymerization, and high steam content (0.5-2.0 kg/kg) in the fluidized bed to reduce residual monomers. This segmentation allows each function to be optimized independently.
Solution Approach 2:
The patent uses the fluidized bed as an intermediary zone between the reaction zone and the product discharge. The fluidized bed receives gas with low steam content from the reaction zone, adds steam through water injection, and then delivers high-steam gas to reduce residual monomers in the polymer particles without affecting the lump-free polymerization that occurred in the reaction zone.
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 reduces the formation of lumps and residual monomers, enhances the roundness and quality of water-absorbent polymer particles, and minimizes steam consumption, resulting in improved product characteristics and process efficiency.
Implementation Method 1
polymerizing droplets of a monomer solution in a surrounding heated gas phase
Implementation Method 2
the gas leaving the reactor is treated in a condenser column (12) with an aqueous solution
Implementation Method 3
a fluidized bed (27)
Data Source
AI summary
The present invention relates to a process for producing water-absorbent polymer particles by polymerizing droplets of a monomer solution in a surrounding heated gas phase in a reactor comprising a gas distributor (3), a reaction zone (5) and a fluidized bed (27), the gas leaving the reactor is treated in a condenser column (12) with an aqueous solution, the treated gas leaving the condenser column (12) is recycled at least partly to the fluidized bed (27), wherein the gas leaving the condenser column (12) comprises from 0.05 to 0.3 kg steam per kg dry gas and the steam content of the gas entering the gas distributor (3) is less than 80% of the steam content of the gas leaving the condenser column (12).