Flow-Metered Valve Control at Low Differential Pressure
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Solution Overview
Problem
Existing pressure independent control valves require a minimum differential pressure to function properly, leading to increased pump head size and operating costs, and suffer from inaccuracies at low starting pressures due to pressure variations.
Innovation Solution
A valve arrangement that measures flow rate using a flow meter and controls the opening degree of the control valve based on these measurements, utilizing a differential pressure regulator and a thermoelectric actuator to maintain accurate flow control even at low pressures, with a control unit that adjusts actuator position through a self-learning model and PWM signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a minimum differential pressure (starting pressure) is required for pressure independent control valves to work properly, then the differential pressure regulator can maintain constant pressure across the valve, but the pump head size and operating costs increase
Solution Approach 1:
The patent implements a feedback control system where a flow meter measures the actual flow rate through the valve, and this measurement is fed back to a control unit. The control unit adjusts the actuator position based on the difference between desired and measured flow, enabling accurate flow control without requiring minimum differential pressure. This feedback mechanism eliminates the need for high starting pressure while maintaining control accuracy.
Solution Approach 2:
The patent replaces the traditional mechanical pressure-independent valve mechanism with an electronically controlled system. Instead of relying on mechanical differential pressure regulation, the system uses an electric actuator controlled by a microprocessor-based control unit that receives feedback from a flow meter, substituting mechanical pressure maintenance with electronic flow control.
2Loss of energy
If the starting pressure is reduced below the minimum required by conventional pressure independent valves, then operating costs decrease, but pressure variations cause inaccurate flow control
Solution Approach 1:
The feedback control system continuously monitors actual flow rate via the flow meter and adjusts the actuator position to compensate for pressure variations. This enables accurate flow control even at low differential pressures where conventional valves fail, directly resolving the contradiction between reduced operating costs and maintained flow control accuracy.
Solution Approach 2:
The system dynamically adjusts the valve opening based on real-time flow measurements and pressure conditions. The control unit modifies the actuator position continuously to maintain desired flow rates despite varying differential pressures, enabling operation across a wide pressure range including very low pressures where traditional static pressure-independent valves cannot function accurately.
3Device complexity
If flow rate is controlled by adjusting the control valve opening without flow measurements, then the system is simpler, but distortions in flow rate occur due to differential pressure variations
Solution Approach 1:
The system incorporates a flow meter that provides real-time feedback on actual flow rate to the control unit. This feedback enables the control unit to compensate for differential pressure variations by adjusting the valve opening dynamically, ensuring accurate flow rate control while maintaining relatively simple system architecture through electronic control rather than complex mechanical 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
Achieves accurate flow control across a wide range of pressures, reducing errors and actuator size, while minimizing pump head size and operating costs.
Implementation Method 1
a flow meter configured to measure the flow rate through the valve body
Implementation Method 2
the differential pressure regulator is configured such that the movable separating member is movable in response to a differential pressure between the first and second sides, and such that the movement of the movable separating member counteracts pressure variations across the valve plug
Implementation Method 3
an actuator operatively connected or connectable to the valve plug for moving the valve plug to adjust the flow rate through the valve body
Data Source
AI summary
A valve arrangement for controlling fluid flow. It comprises a valve plug located within the valve body, an actuator operatively connected or connectable to the valve plug for moving the valve plug to adjust the flow rate through the valve body, a differential pressure regulator configured to limit variations of the differential pressure across the valve plug when fluid is flowing through the valve body, a flow meter configured to measure the flow rate through the valve body, and a control unit. The control unit is configured to receive a request input signal representative of a desired flow rate through the valve body, and a flow input signal from the flow meter representative of the measured flow rate. The control unit is configured to, based on the received signals, send a control signal to the actuator to move the valve plug or to maintain the valve plug in its position.