Radiometric Level Measurement in High-Pressure Polymerization Separation
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Solution Overview
Problem
Accurate level measurement in high-pressure polymerization processes is challenging due to variations in process gas density and composition, especially when producing different polyethylene grades, which can lead to inaccurate readings and safety issues, particularly in larger scale plants with increased production demands.
Innovation Solution
A radiometric level measurement system is implemented in the first separation vessel, using at least two radioactive sources and three radiation detectors installed at different heights, with detectors positioned within or close to oriented cavities in the vessel wall, allowing for precise measurement of the liquid fraction level and controlling the product discharge valve effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radiometric level measurement is used in high-pressure polymerization processes, then reliability of level measurement is improved, but measurement precision deteriorates due to variations in process gas density and composition
Solution Approach 1:
The measurement system is segmented into multiple radiation detectors positioned at different heights (at least three detectors) within oriented cavities in the vessel wall. Each detector measures radiation attenuation at its specific location, and the combined data from multiple detectors enables accurate determination of the liquid-gas interface level despite variations in gas density and composition throughout the vessel.
Solution Approach 2:
The invention transitions from a single-point measurement approach to a multi-dimensional measurement approach by positioning multiple radiation detectors at different heights and locations within the vessel wall cavities. This spatial distribution across multiple dimensions allows the system to compensate for variations in gas properties and accurately identify the liquid level interface.
2Productivity
If larger scale plants with increased production demands are operated, then productivity is improved, but measurement precision deteriorates due to increased variation in process gas density and composition
Solution Approach 1:
The radiation detection system is divided into multiple segments (at least three detectors) positioned at different heights within oriented cavities in the vessel wall. This segmentation allows each detector to independently monitor radiation attenuation at its specific location, and the combined information from all detectors provides accurate level measurement even in large-scale plants with significant variations in gas density and composition.
Solution Approach 2:
The system uses feedback from multiple radiation detectors positioned at different heights to continuously monitor and determine the liquid-gas interface level. The oriented cavities in the vessel wall provide structured pathways for radiation detection, enabling the system to adapt to varying production conditions and maintain measurement accuracy across different operating ranges.
3Reliability
If radioactive sources are installed for level measurement, then reliability of measurement is improved, but device complexity increases due to multiple sources and detectors at different heights
Solution Approach 1:
The invention merges multiple radiation detectors into a coordinated measurement system with oriented cavities in the vessel wall. The cavities are positioned to receive radiation from the radioactive sources and direct it to the detectors, combining the functions of multiple components into an integrated system that maintains reliability while managing complexity through structured arrangement.
Solution Approach 2:
The oriented cavities in the vessel wall serve as intermediaries between the radioactive sources and the radiation detectors. These cavities provide structured pathways that guide radiation from the sources to the detectors positioned at different heights, simplifying the overall system architecture by providing fixed, predetermined radiation paths rather than requiring complex positioning mechanisms.
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 solution provides a high-accuracy level measurement, enabling safer and more reliable operation of polymerization units, allowing for longer service life of radioactive sources and facilitating fast grade changes between polyethylene types with reduced production of off-spec material and contamination of final polymers.
Implementation Method 1
The operation principle is based on the properties of gamma rays, which loose intensity as they passes through material. Attenuation of the gamma radiation when passing through the vessel is measured by a detector.
Implementation Method 2
The intensity of the passing radiation is predictably affected by the type of the material, the density of the material and the total thickness of the object, and by the distance between the gamma ray source and the detector.
Data Source
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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 filling level of the liquid fraction in the separation vessel is measured by a radiometric level measurement system comprising at least two radio-active sources and at least three radiation detectors and the filling level is controlled by a product discharge valve which operates based on data coming from the level measurement system, and wherein radioactive sources are installed at at least two different heights of the separation vessel, and radiation detectors are installed at least three different heights of the separation vessel 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 a process for separating polymeric and gaseous components.