Loop Slurry Reactor Propylene Polymerization
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Solution Overview
Problem
Current propylene polymerization methods and systems face challenges in achieving high space time yield (STY) and efficient production rates in loop slurry reactors, with existing STYs typically below 0.36 ton polypropylene/hr/m3, and require complex configurations for handling high production rates.
Innovation Solution
A method and system for propylene polymerization in a loop slurry reactor that operates at bulk polymerization conditions, achieving a STY greater than 0.36 and less than 0.60 ton polypropylene/hr/m3, utilizing specific operating conditions and configurations such as continuous take-off valves, flashline heaters, and a heat exchange system to manage coolant flow and temperature differences, and recycling vapor streams to enhance production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If propylene polymerization is conducted in a loop slurry reactor to achieve high production rates, then the space time yield increases, but the complexity of the system increases due to requirements for multiple continuous take-off valves, flashline heaters, and sophisticated heat exchange systems
Solution Approach 1:
The reactor system is segmented into multiple vertical legs with bends, creating a loop configuration that allows continuous polymerization. The discharge system is segmented into multiple continuous take-off valves, each handling a portion of the total polymerization product flow, enabling high production rates while distributing system complexity across multiple manageable components
Solution Approach 2:
Flashline heaters are introduced as intermediary devices between the reactor discharge and the separator. These heaters temporarily hold and heat the polymerization product, facilitating phase separation and enabling continuous operation without requiring direct complex integration between all system components
2Productivity
If the production rate is increased to achieve high space time yield, then more polymerization product must be handled, but the steam and electricity consumption increases
Solution Approach 1:
The heat exchange system is designed to optimize temperature parameters by controlling coolant flow rates and temperature differentials. By carefully managing these parameters, the system achieves high production rates while minimizing the energy input required for heating and cooling operations
Solution Approach 2:
The system utilizes the exothermic heat generated during polymerization itself to drive certain process requirements. The heat exchange system recycles and reuses this generated heat, reducing the need for external steam and electricity inputs, thereby achieving high productivity with lower energy consumption
3Productivity
If continuous polymerization is implemented to maintain high space time yield, then unreacted propylene and catalyst diluent must be continuously managed, but the complexity of vapor stream recycling increases
Solution Approach 1:
The system implements continuous polymerization with continuous discharge through multiple valves, maintaining steady-state operation that maximizes space time yield. The vapor stream recycling is also continuous, with unreacted propylene and catalyst diluent being constantly separated and returned to the reactor, eliminating idle periods and maintaining high productivity
Solution Approach 2:
The separator and vapor recycling system serve multiple functions simultaneously: they separate polymerization product from unreacted monomer, condense vapor streams, recycle materials back to the reactor, and manage catalyst diluent. This multi-functionality reduces the need for separate dedicated equipment for each task, managing complexity while maintaining continuous high-rate operation
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 method and system significantly increase the space time yield and production rate of polypropylene, achieving 3 to 5 lb polypropylene/hr/gallon of reactor volume, while reducing steam and electricity usage, and allow for efficient recovery and recycling of propylene, improving overall process efficiency.
Implementation Method 1
polymerizing propylene in a loop slurry reactor under bulk polymerization conditions to produce polypropylene
Implementation Method 2
coolant flow rate, cooling passes, heat exchanger
Implementation Method 3
coolant flow rate... cooling passes... heat exchanger
Implementation Method 4
flowing the polymerization product through a plurality of flashline heaters (each couple to a continuous take-off valve) to a separator
Implementation Method 5
separating, in the separator, the polymerization product into a polypropylene product stream and a vapor product stream
Data Source
AI summary
Disclosed are a method and system for propylene polymerization utilizing a loop slurry reactor. The method can include polymerizing propylene in a loop slurry reactor under bulk polymerization conditions to produce polypropylene. The propylene polymerization system can include i) a loop slurry reactor and a heat exchange system that is configured to cool the legs of the loop slurry reactor and/or ii) an inlet manifold that is configured to connect flashline heaters to a separator.