Positive Displacement Pump Control for Leakage-Compensated Metering
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Solution Overview
Problem
Leakage losses in line systems for high-pressure liquid plastic components become significant due to pressure gradients and wear, making precise metering challenging, especially during shutdown or waiting times, as material losses are difficult to estimate and vary with changing conditions.
Innovation Solution
A method and conveyor system that use a pressure measuring device to maintain a target liquid pressure by adjusting the positive displacement pump's operation, accounting for leakage losses by adding the conveying loss rate to the target delivery rate, ensuring precise liquid delivery to the mixer head, even during shut-off periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If positive displacement pumps are used to convey liquid plastic components at high pressure, then the liquid can be delivered to the mixer head, but leakage losses occur due to pressure gradients and wear, making precise metering difficult
Solution Approach 1:
The patent implements a feedback mechanism where a pressure measuring device continuously monitors the actual liquid pressure in the line system. Based on this feedback, the control system adjusts the positive displacement pump's operation to maintain the target pressure, thereby compensating for leakage losses. The system measures actual pressure, compares it to target pressure, and modifies pump operation accordingly to maintain precise metering despite wear and pressure gradients
Solution Approach 2:
The patent changes the operating parameters of the positive displacement pump based on measured pressure conditions. By adjusting pump speed or displacement volume in response to pressure feedback, the system compensates for leakage losses that vary with pressure and wear. This dynamic parameter adjustment allows the system to maintain accurate metering despite changing conditions
2Ease of operation
If the shut-off member is used to stop conveying during shutdown or waiting times, then the line system can be isolated, but leakage losses become variable and difficult to estimate, affecting metering precision
Solution Approach 1:
The pressure measuring device provides continuous feedback on actual pressure conditions even during shutdown periods when the shut-off member is closed. This feedback enables the control system to monitor and compensate for leakage losses that occur through the closed shut-off member or in the line system, maintaining metering accuracy by adjusting pump operation based on real-time pressure data
3Quantity of substance
If the positive displacement pump operates at higher speeds to compensate for leakage losses, then the target delivery rate can be maintained, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts pump operating parameters based on actual pressure feedback rather than using fixed high-speed operation. By changing pump speed or displacement volume in response to measured pressure conditions, the system compensates for leakage losses while minimizing energy consumption. The control system optimizes the balance between delivery rate maintenance and energy use
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 allows for precise compensation of leakage losses, maintaining consistent pressure and flow rates, thereby ensuring accurate metering and minimizing material losses, even with varying shutdown times and changing viscosities of thixotropic liquids.
Implementation Method 1
the actual liquid pressure in the line system is ascertained by means of a pressure measuring device
Implementation Method 2
The components are conveyed by the conveyor system to the mixer head by means of positive displacement pumps
Data Source
AI summary
A method and a device for compensating leakage losses in a line system, in which at least one positive displacement pump and at least one shut-off member are provided, wherein the method and device can be used for the isobaric metering of liquid plastic components and wherein the actual liquid pressure in the system is determined by way of a pressure measuring device and, when the shut-off member is closed is regulated to a pressure target value by actuation of the positive displacement pump, wherein the conveying loss rate of the positive displacement pump, which ensues to maintain the pressure target value when the shut-off member is closed is added to a target delivery rate in order to compensate for the leakage loss occurring at the corresponding pressure target value.