Progressing Cavity Pump Injection for Polymer Melt Wear Reduction
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Solution Overview
Problem
Existing methods for incorporating additives into polymeric materials, such as polyester fibers, face issues like high water consumption, environmental pollution, and gear pump wear due to abrasive particles, leading to inefficient and costly processes.
Innovation Solution
A dual progressing cavity pump system is used to inject liquid formulations into a polymer melt, with a first pump metering and a second pump increasing pressure, allowing for efficient and accurate delivery of additives with minimal wear and reduced environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If gear pumps are used to inject liquid formulations with abrasive particles into polymer melt, then the formulation can be delivered at high pressure, but the pump suffers from high levels of wear
Solution Approach 1:
The patent replaces the gear pump mechanism with a progressing cavity pump (PCP) system. The PCP uses a rotor rotating within a cavity to propel liquid through peristaltic compression, eliminating the gear meshing mechanism that causes wear with abrasive particles. This substitution maintains high pressure delivery capability while dramatically reducing wear on the pumping mechanism.
Solution Approach 2:
The patent changes the operating parameters of the pumping system by using a PCP design that can handle abrasive particles without the mechanical contact that causes gear pump wear. The system maintains high pressure (up to 200 bar) while the cavity design allows particles to be pumped without direct mechanical contact, thus changing the parameter of particle-tolerant pressure delivery.
2Adaptability or versatility
If gear pump tolerances are widened to accept larger pigment particles, then particle size constraints are relaxed, but the pump cannot adequately pressurize low viscosity materials
Solution Approach 1:
The patent substitutes the gear pump system with a progressing cavity pump that uses a different mechanical principle - peristaltic compression within a cavity. This allows the system to accommodate larger pigment particles without requiring tight tolerances, while still generating the necessary pressure through the cavity compression mechanism rather than gear meshing.
3Measurement precision
If gear pumps operate at high pressure with liquid formulations, then accurate metering is achieved, but slip increases causing localised heating and accelerated wear
Solution Approach 1:
The patent replaces the gear pump with a progressing cavity pump that eliminates the slip problem inherent in gear mechanisms. The PCP's cavity design provides positive displacement without the clearance gaps that cause slip, thereby maintaining metering accuracy at high pressure while preventing the localized heating and wear caused by slippage.
Solution Approach 2:
The patent converts the potential harm of high pressure operation into a benefit by using the PCP's cavity compression mechanism that maintains pressure without causing slip. The high pressure is achieved through the cavity's peristaltic action rather than gear meshing, eliminating the harmful effects of slip-related heating and wear while maintaining accurate metering.
4Reliability
If abrasive particles are milled to very small sizes to reduce gear pump wear, then pump longevity is improved, but the process becomes time-consuming and costly
Solution Approach 1:
The patent substitutes the gear pump with a progressing cavity pump that is inherently tolerant of abrasive particles. This eliminates the need for extensive milling of particles to protect the pump, as the PCP's cavity design allows particles to be pumped without causing wear to the pumping mechanism. This saves significant time and cost in particle preparation.
5Productivity
If liquid formulations with clumps are injected into polymer melt, then formulation delivery is achieved, but clumps cause problems in the injection process
Solution Approach 1:
The patent replaces the gear pump with a progressing cavity pump that uses peristaltic compression to deliver formulations. This mechanism is better at handling formulations with clumps or particulate matter, as the cavity compression gently propels the material through the pump without creating the high shear forces that cause clumping. This maintains injection quality while improving productivity.
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 system enables efficient and cost-effective injection of additives into polymeric materials with reduced wear and environmental impact, maintaining consistent pressure and accuracy over extended periods.
Implementation Method 1
a first progressing cavity pump (pcp) which is arranged to meter the liquid formulation into a second pcp
Implementation Method 2
a second pcp which is arranged to increase the pressure of the liquid formulation
Implementation Method 3
the second pcp which is arranged to increase the pressure of the liquid formulation
Implementation Method 4
a delivery valve, controlled by an actuator, downstream of the second pcp and arranged to control passage of the pressurised liquid formulation into a molten polymer stream
Implementation Method 5
a pressure transducer positioned in a flow line between the first and second pcps
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Injection apparatus for injecting a liquid formulation into a molten polymer at high pressure includes a reservoir containing liquid formulation at ambient temperature and pressure which is arrange to flood-feed pump body 26 of a first progressing cavity pump (pep) 4. The first pep 4 is driven by motor 6 and is arranged to accurately meter the liquid formulation into a second pep 8 which is downstream of the first pep and is arranged to increase the pressure of the liquid formulation by 200 bar or more. Downstream of pump 8 is a delivery valve 14 arranged to control passage of liquid formulation, via outlet 17, into pressurised molten polymer stream 75 which is present in an extruder 77.