Segmented Heating Channel Devolatilization Apparatus
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Solution Overview
Problem
Conventional flat plate heat exchangers are inadequate for high-throughput devolatilization processes in large polymerization plants, as they reach physical size limitations and fail to achieve sufficient devolatilization efficiency, limiting the capacity of polymerization plants to around 330,000 metric tons per annum.
Innovation Solution
A devolatilization apparatus featuring a multiplicity of plates with heating channels divided into two zones, where the first zone maintains pressure above the bubble point pressure to prevent flashing and the second zone induces a pressure drop for complete vaporization, allowing for higher flow rates and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional flat plate heat exchanger designs are used, then the physical size and capacity are limited, but the throughput and devolatilization efficiency are insufficient for large polymerization plants
Solution Approach 1:
The heating channel is divided into two distinct zones: a first zone with a larger hydraulic radius for heating while maintaining pressure above bubble point, and a second zone with a smaller hydraulic radius for inducing pressure drop and complete vaporization. This segmentation allows each zone to perform its specific function optimally, resolving the contradiction between throughput and devolatilization efficiency.
Solution Approach 2:
Different sections of the heating channel are designed with different hydraulic radii to create locally optimized flow conditions. The first zone has larger hydraulic radius for stable heating, while the second zone has smaller hydraulic radius for intense vaporization, allowing the system to achieve both high throughput and complete devolatilization simultaneously.
2Reliability
If the heating channel has uniform hydraulic radius, then the design is simple, but the pressure control and vaporization efficiency are insufficient
Solution Approach 1:
The heating channel is segmented into two zones with different hydraulic radii. The first zone maintains larger hydraulic radius for pressure stability, while the second zone reduces hydraulic radius for complete vaporization. This segmentation achieves superior vaporization completeness without excessive design complexity.
Solution Approach 2:
The hydraulic radius parameter is changed along the flow path, transitioning from a larger value in the first zone to a smaller value in the second zone. This parameter change enables the system to achieve both pressure control and complete vaporization, resolving the contradiction between vaporization completeness and design complexity.
3Stress or pressure
If the first zone length is increased relative to total channel length, then pressure maintenance is improved, but the overall channel length and device size increase
Solution Approach 1:
The channel design optimizes the local quality of each zone: the first zone has larger hydraulic radius specifically for pressure maintenance, while the second zone has smaller hydraulic radius for compact vaporization. This localized optimization allows adequate pressure maintenance without excessive overall channel length.
Solution Approach 2:
The hydraulic radius parameter is strategically changed between zones to achieve pressure maintenance in the first zone and compact vaporization in the second zone. This parameter transition allows the system to maintain pressure above bubble point without requiring excessive channel length, resolving the contradiction between pressure control and device size.
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 apparatus achieves a throughput 1.2 to 10 times higher than conventional designs, enabling the processing of larger volumes of polymer products with residual volatile components below 2000 wppm, thus overcoming the capacity limitations of traditional systems.
Implementation Method 1
a plurality of heating elements adapted to heat at least some of the plates so as to increase the temperature of the flowable material as it flows through the heating channels
Implementation Method 2
the design or operation of at least some of the heating channels is such that the pressure of the flowable material at essentially all positions within the first zone of the heating channels exceeds the bubble point pressure of the flowable material
Implementation Method 3
the second zone is adapted to receive the flowable material from the first zone and has at least one outlet adapted to discharge the flowable material into the collection-and-volatile-separation vessel, wherein at least a portion of the second zone has a smaller hydraulic radius than the average hydraulic radius of the first zone
Data Source
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AI summary
Embodiments of the invention provide an apparatus or process for devolatilization of flowable materials (such as molten polymers with entrained or dissolved solvent or unreacted monomers or comonomers) using a plate heater having heating channels, the design or operation of which heating channels maintains the flowable material above its bubble point pressure during passage through a larger first zone and then induces flashing in, or downstream of, a smaller second zone of the heating channel. The apparatus enables a higher throughput per heating channel while achieving equivalent or better devolatilization, as compared to current devolatilization apparatus.