Tubular Loop Reactor Diameter Increase for Slurry Polymerization
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Solution Overview
Problem
High slurry concentrations in olefin polymerization processes in loop reactors lead to increased energy consumption and pump design complexity, necessitating high circulation velocities to prevent fouling and ensure thermal and compositional distribution, which is costly and risky for new plant operations.
Innovation Solution
Increasing the internal diameter of tubular reactors above conventional limits allows for high solids loadings at lower circulation velocities, maintaining acceptable cross-sectional concentration distributions and reducing energy consumption, while minimizing fouling and pressure drops, by maintaining a Froude number below 30 and controlling particle size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high circulation velocities are used to maintain good thermal and compositional distribution and prevent solids settling, then polymer productivity and homogeneity are improved, but specific energy consumption and pump design complexity increase
Solution Approach 1:
The patent changes the geometric parameter of the reactor (internal diameter) from conventional sizes to larger diameters. This parameter change allows the system to operate at lower circulation velocities while maintaining adequate mixing and heat transfer, thereby reducing specific energy consumption without sacrificing polymer productivity
Solution Approach 2:
The patent transitions from small-diameter reactors requiring high velocity circulation to large-diameter reactors where the cross-sectional area provides inherent mixing and heat transfer capabilities. This dimensional change in reactor scale fundamentally alters the flow dynamics and energy requirements
2Productivity
If high slurry concentrations are used to increase reactor residence time and reduce downstream diluent treatment, then productivity is improved, but circulation velocity and head requirements increase leading to higher energy consumption
Solution Approach 1:
The patent changes the reactor internal diameter parameter to larger sizes, which allows high slurry concentrations to be circulated at lower velocities. The larger cross-sectional area reduces the velocity required to maintain adequate mixing and prevent settling, thereby enabling high productivity operations with reduced energy consumption
3Use of energy by moving object
If larger reactor diameters are used to reduce circulation velocity and energy consumption, then specific energy consumption is reduced, but maintaining acceptable cross-sectional concentration distributions becomes more difficult
Solution Approach 1:
The patent creates equipotential conditions in the large-diameter reactor by operating at optimized circulation velocities that ensure uniform distribution of solids and liquid phases across the cross-section. The larger diameter provides a more uniform velocity profile and reduced wall effects, maintaining compositional homogeneity without requiring excessive circulation speeds
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 specific energy consumption, minimizes reactor fouling, and enables the operation of larger reactors with reduced pressure drops and pump requirements, enhancing operational efficiency and safety, particularly at high solids loadings and large diameters.
Implementation Method 1
the slurry is circulated in the reactor typically by means of a pump or agitator
Implementation Method 2
The heat of polymerisation is typically removed using indirect exchange with a cooling medium, preferably water, in jackets surrounding at least part of the tubular loop reactor
Implementation Method 3
an olefin monomer and optionally olefin comonomer are polymerised in the presence of a catalyst
Data Source
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AI summary
A process comprising polymerising in a loop reactor of a continuous tubular construction an olefin monomer optionally together with an olefin comonomer in the presence of a polymerisation catalyst in a diluent to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the average internal diameter of at least 50% of the total length of the reactor is at least 650 millimeters, the solids concentration in the reactor is at least 15 volume % and having a particle size distribution such that (D90-D10)/D50 is less than 2.