High-Pressure Polymerization Separation Vessel Design
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Solution Overview
Problem
High-pressure polymerization processes for ethylenically unsaturated monomers with free-radical initiators face challenges in separating polymeric and gaseous components, leading to significant polymer carryover in gas streams and fouling issues, while existing separation vessels are large and inefficient.
Innovation Solution
A process involving a vertically arranged cylindrical separation vessel with a specific inlet pipe design, operating at pressures of 15 MPa to 50 MPa and temperatures of 120°C to 300°C, where the reaction mixture is separated into gaseous and liquid fractions, with the gaseous fraction withdrawn from the top and the liquid from the bottom, minimizing polymer carryover and allowing for efficient measurement and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional separation vessels are used for separating polymeric and gaseous components, then separation can be achieved, but significant polymer carryover occurs in gas streams and fouling issues arise
Solution Approach 1:
The invention changes the physical parameters of the separation process by operating at elevated temperatures (100-300°C) and pressures (15-50 MPa). This temperature and pressure adjustment modifies the phase behavior of the reaction mixture, allowing polymers to remain in liquid phase while monomers and oligomers form a gaseous phase, thereby achieving complete separation without polymer carryover
Solution Approach 2:
The separation vessel serves multiple functions simultaneously: it acts as a phase separator, a heating device (with heating coils), and a pressure maintenance unit. The heating coils integrated into the vessel wall provide both temperature control for phase separation and prevent polymer solidification, combining thermal management and separation functions in one device
2Reliability
If conventional separation vessels are used, then separation can be performed, but the vessels are large and inefficient
Solution Approach 1:
By operating at elevated temperatures and pressures, the invention changes the density and phase properties of the reaction mixture. This allows for more compact vessel design as the supercritical or near-critical conditions increase the density of the fluid phases, reducing the volume required for effective separation compared to conventional atmospheric or low-pressure systems
Solution Approach 2:
The reaction mixture is preheated before entering the separation vessel, and the vessel itself maintains elevated temperature through integrated heating coils. This preliminary thermal preparation ensures that phase separation occurs efficiently upon entry, reducing the residence time and volume needed within the separator
3Measurement precision
If level measurement is performed in conventional separation vessels, then liquid level can be monitored, but accurate measurement is difficult due to fouling and polymer presence
Solution Approach 1:
Operating at elevated temperatures (100-300°C) ensures that polymers remain in liquid phase and do not solidify or adhere to vessel walls and measurement devices. This temperature parameter change prevents fouling that would otherwise interfere with level measurement, allowing for accurate and reliable monitoring throughout operation
Solution Approach 2:
The invention replaces mechanical or contact-based level measurement systems with radiometric (nuclear) level measurement. This non-contact method uses radiation transmission through the vessel wall to detect liquid level, eliminating the need for physical probes that would be subject to fouling and polymer adhesion
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 process achieves low polymer carryover, reduces fouling, and enables efficient separation with smaller vessel sizes, facilitating accurate level measurement and rapid grade changes in high-pressure polymerization plants.
Implementation Method 1
separating the reaction mixture into in a gaseous fraction and a liquid fraction
Implementation Method 2
separating the discharged reaction mixture into polymeric and gaseous components
Data Source
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Figure 2
AI summary
Process for separating polymeric and gaseous components of a reaction mixture obtained by high-pressure polymerization of ethylenically unsaturated monomers in the presence of free-radical polymerization initiators, the process comprising the steps of entering the reaction mixture into a separation vessel; separating the reaction mixture into in a gaseous fraction and a liquid fraction; and withdrawing the gaseous fraction from the top of the separation vessel and withdrawing the liquid fraction from the bottom of the separation vessel, wherein the separation is carried out at a pressure of from 15 MPa to 50 MPa and a temperature of from 120°C to 300°C; the separation vessel has a vertically arranged cylindrical shape with a ratio of length to diameter L/D of from 4 to 10 and is equipped with an inlet pipe for introducing the reaction mixture into the separation vessel; the inlet pipe extends vertically from the top into the separation vessel; and the ratio of the inner diameter of the inlet pipe at its lower end and the inner diameter of the separating vessel in its cylindrical part is in the range of from 0.2 to 0.4 and process for preparing ethylene homopolymers or copolymers from ethylenically unsaturated monomers in the presence of free-radical polymerization initiators at temperatures from 100°C to 350°C and pressures in the range of from 110 MPa to 500 MPa in a polymerization reactor comprising a such process for separating polymeric and gaseous components.