Polyester Particle Fluidization for High Throughput
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Solution Overview
Problem
High-throughput polyester production in large reactors leads to increased product pressure, limited reactor temperature, longer residence times, and higher building costs, along with issues of product sticking and damage during conveying.
Innovation Solution
A process involving high-rate descent of polyester particles through reactors, with a dedusting device before preheating, and conveying heated particles over a large vertical distance using pneumatic conveying to minimize product abrasion and dust formation, allowing for efficient treatment of high quantities of polyester in the solid phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large reactors are used to treat high throughputs in the solid phase, then productivity is improved, but product pressure increases which limits maximum permissible reactor temperature and leads to longer residence times and even larger reactors
Solution Approach 1:
The patent applies fluidization technology to create a dynamic state where particles are suspended in gas flow, allowing high throughput processing without excessive pressure buildup. The fluidized bed maintains constant particle motion and gas-liquid contact, enabling efficient heat and mass transfer at high rates without the pressure constraints of conventional packed bed reactors
Solution Approach 2:
The patent uses gas flow to fluidize the polyester particles, creating a pneumatic suspension that allows material to be conveyed and processed without mechanical pressure buildup. The gas flow rate is controlled to maintain fluidization while limiting pressure drop across the reactor, enabling high throughput with manageable pressure
2Productivity
If large reactors are used to treat high throughputs, then productivity is improved, but building expenditure increases due to the need for large reactors and local heating above the reactor
Solution Approach 1:
The patent combines the heating function with the reaction zone by using the same fluidized bed environment for both heat transfer and chemical reaction. The heating medium is integrated into the gas flow system, eliminating the need for separate heating apparatus and reducing building infrastructure requirements
Solution Approach 2:
The gas flow system serves dual purposes: it fluidizes the particles for reaction and simultaneously provides heating through the gas temperature. This integration eliminates the need for separate heating infrastructure and reduces building expenditure on support structures for local heating above the reactor
3Productivity
If heated particles are conveyed over large vertical distances, then treatment capacity is improved, but product damage during conveying increases
Solution Approach 1:
The patent uses pneumatic conveying where hot particles are transported through a gas stream rather than mechanical conveyors. The gas flow gently suspends and moves the particles, minimizing mechanical impact and abrasion while enabling large vertical transport distances without product damage
Solution Approach 2:
The gas flow acts as an intermediary medium between the heating zone and the reaction zone, gently transporting the heated particles without direct mechanical contact. This intermediary gas stream prevents particle damage while enabling efficient vertical conveyance over large distances
4Productivity
If process gas flows through the reactor at high rates, then treatment capacity is improved, but pressure drop across the reactor increases which limits permissible amount of process gas and leads to longer residence times
Solution Approach 1:
The fluidized bed creates a dynamic particle-gas interface that reduces resistance to gas flow. The constant particle motion and suspension prevent channeling and reduce pressure drop, allowing high gas flow rates for heat and mass transfer without the pressure constraints of conventional fixed bed reactors
Solution Approach 2:
The pneumatic fluidization system optimizes gas flow through the particle bed by maintaining a controlled suspension state. The gas flow rate is adjusted to achieve optimal fluidization where pressure drop is minimized while maintaining high treatment capacity through efficient gas-solid contact
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 product sticking, gas flow resistance, and damage, enabling economical operation with smaller reactors, lower pressure drops, and reduced building costs while maintaining high throughput and efficient processing of polyester particles.
Implementation Method 1
the treatment in the solid phase of the polyester takes place in a reactor, the sinking speed of the particles being more than 2.6 to 6 meters per hour
Implementation Method 2
prior to the preheating step, the polyester pre-polymer particles are preferably passed through a dedusting device
Implementation Method 3
at least one preheater for heating the semi-crystalline polyester pre-polymer particles to a suitable reaction temperature
Implementation Method 4
at least one reactor for the production of polyester polymer particles with an intrinsic viscosity between 0.70 and 0.95 dl/g, wherein the increase in intrinsic viscosity is at least 0.05, in particular at least 0.1dl/g
Data Source
AI summary
The invention relates to a method and to a device for producing a thermoplastic polyester, having the following steps: a) producing polyester pre-polymer particles; b) crystallizing the polyester pre-polymer particles for producing partially crystalline polyester pre-polymer particles; c) heating the partially crystalline polyester pre-polymer particles to a suitable reaction temperature for producing heated polyester pre-polymer particles; d) reacting the heated polyester pre-polymer particles for producing polyester polymer particles having an intrinsic viscosity between 0.70 and 0.95 dl/g. The reaction in step d) takes place in at least one reactor through which the particles flow by means of gravity. The dwell time in the reactor equals between 6 and 30 hours. The particles are supplied at least to step d) at a mass flow of between 40 and 100 t/h. The present invention is characterized in that a settling rate of the particles in the reactor equals between 2 and 6m/h.