Monomer Separation via Dual-Pressure Flash Segmentation
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Solution Overview
Problem
In polymerization processes, especially slurry polymerization, the separation and recycling of monomers and hydrocarbons are inefficient due to the energy-intensive process of compressing vapors to recycle them, leading to significant losses and emissions.
Innovation Solution
A process involving a high pressure flash step followed by a low pressure treatment system, where a portion of the high pressure recycle stream is let down in pressure and passed to a low pressure separator, optimizing the separation of monomers from light components, thereby reducing the need for compression and enhancing recycling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high pressure flash step is used to separate and recycle monomers and hydrocarbons, then separation efficiency is improved, but compression energy consumption increases
Solution Approach 1:
The recycle stream is divided into multiple pressure levels. A first separator operates at high pressure to perform the primary separation function, while a second separator operates at reduced pressure to complete the separation. This segmentation allows the system to achieve high separation efficiency without requiring compression of the entire recycle stream, as only portions need to be recompressed to different extents based on their destination.
Solution Approach 2:
The system utilizes pressure as a varying parameter to optimize separation and recycling. By operating separators at different pressure levels (high pressure for the first separator, reduced pressure for the second separator), the system can selectively condense and recycle different portions of the vapor stream without uniform compression, thereby reducing overall energy consumption while maintaining separation efficiency.
2Object-affected harmful factors
If purging is increased to remove impurities, then impurity levels are reduced, but monomer and comonomer losses increase
Solution Approach 1:
The purge function is segmented and distributed across multiple separation stages operating at different pressures. The first separator at high pressure handles bulk impurity removal, while the second separator at reduced pressure provides additional purification. This segmentation allows impurities to be removed effectively at each stage without requiring excessive purging, thereby minimizing monomer and comonomer losses while maintaining low impurity levels in the recycled streams.
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 increases monomer and comonomer recycling efficiency, reducing losses and emissions, achieving monomer efficiencies above 99.5% and comonomer efficiencies above 95%, while minimizing the need for compression and purging of hydrogen and other impurities.
Implementation Method 1
a first separator at a pressure greater than 0.5 MPa for separating a vapour stream comprising unreacted monomer and unreacted comonomer from the solids
Implementation Method 2
a second separator at a pressure of less than 0.5 MPa which is operated to separate a stream comprising at least some of the light components other than monomer
Implementation Method 3
the second separator is operated to provide a separation of hydrogen, nitrogen and methane from monomer and heavier components present
Implementation Method 4
A common method to achieve this in slurry polymerisation is to heat the withdrawn slurry to vaporise the liquid medium, and to separate the vapour from the polymer solids
Data Source
AI summary
The present invention relates to a process for enhancing the separation of monomer components from light components other than monomer, which process comprises: A) Providing a first stream comprising monomer and light components other than monomer, B) Passing the first stream to a first separator at a first pressure to separate a second stream comprising at least some of the light components other than monomer and provide a third stream comprising monomer, C) Passing a portion of the third stream and a fourth stream comprising monomer and light components other than monomer to a second separator at a second pressure which is lower than the first pressure to separate a fifth stream comprising at least some of the light components other than monomer from the fourth stream and provide a sixth stream comprising monomer.