Flowmeter Zero Flow Compensation Method
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Solution Overview
Problem
Flowmeters with non-zero zero flow measurements incur constant measurement errors, which affect the accuracy of flow measurements through the measuring tube.
Innovation Solution
A method that assigns continuous dwell times to flow and zero flow intervals based on a flow threshold, determines deviation volumes, and compensates zero flow by subtracting it from measured flow in preceding intervals, reducing measurement errors by comparing deviation volumes to a threshold deviation volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If zero flow measurement is performed continuously, then measurement completeness is improved, but measurement precision deteriorates due to constant error accumulation
Solution Approach 1:
The patent segments the continuous measurement process into distinct intervals: zero flow intervals (where flow is below threshold) and flow intervals (where flow is above threshold). This segmentation allows different processing strategies to be applied to each type of interval, improving overall measurement precision by treating zero flow and actual flow measurements differently.
Solution Approach 2:
The patent performs preliminary identification of zero flow intervals before actual flow measurement. By detecting and marking zero flow intervals in advance, the system can exclude these problematic measurements from the final flow calculation, preventing error accumulation before it affects the results.
2Difficulty of detecting and measuring
If flow threshold is set low, then zero flow detection sensitivity is improved, but flow interval identification accuracy deteriorates
Solution Approach 1:
The patent employs dynamic threshold adjustment based on flow conditions. The system adapts the flow threshold dynamically, raising it during periods of actual flow to improve interval identification accuracy, and lowering it during stagnation periods to enhance zero flow detection sensitivity. This dynamic adaptation resolves the contradiction between detection sensitivity and measurement accuracy.
Solution Approach 2:
The patent changes the flow threshold parameter based on operational context and flow patterns. By adjusting this critical parameter dynamically, the system optimizes both zero flow detection sensitivity and flow interval accuracy for different operating conditions, eliminating the need for a fixed threshold that would compromise one aspect for the other.
3Productivity
If continuous flow monitoring is performed, then process control is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic sampling and evaluation of flow data instead of continuous processing. By evaluating flow intervals periodically and only processing data during flow intervals (rather than continuously monitoring all data including zero flow periods), the system maintains effective process control while significantly reducing controller energy consumption during stagnation periods.
Solution Approach 2:
The patent applies partial processing by focusing computational resources only on relevant flow intervals rather than processing all time periods equally. During zero flow intervals, minimal processing is performed, while during flow intervals, full monitoring and processing are activated. This partial action approach maintains productivity during actual flow while conserving energy during stagnation.
Data Source
AI summary
Described and shown is a method for operating a flowmeter (1) having a measuring tube (2), wherein the flow (d) of a medium (4) through the measuring tube (2) is measured. A continuous dwell time of the measured flow (d) greater than or equal to a flow threshold (ds) is assigned to a flow interval (ΔtD,1, ΔtD,2) and a flow volume (V1, V2) is determined from the measured flow (d) in the flow interval (ΔtD,1, ΔtD,2). In each case, a continuous dwell time of the measured flow (d) less than the flow threshold (ds) is assigned to a zero flow interval (ΔtN,1). In each case, a deviation volume of the flow volume (V1, V2) in one of the flow intervals (ΔtD,1, ΔtD,2) from a reference flow volume is determined and the deviation volume is compared to a threshold deviation volume. If the deviation volume in one of the flow intervals (ΔtD,1, ΔtD,2) is less than the threshold deviation volume, a zero flow through the measuring tube (2) is determined and compensated using the measured flow (d) in the zero flow interval (ΔtN,1) directly preceding the flow interval (ΔtD,1, ΔtD,2).