Process Water Analyzer Dosing via Air Cushion Pressure Compensation
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Solution Overview
Problem
Existing process water analyzers face inaccuracies in pumping a precise volume of process liquid due to unknown vertical liquid column length affecting air cushion expansion, leading to systematic overdosage and photometric faults.
Innovation Solution
A process water analyzer with a dosage chamber positioned vertically higher than the reservoir tank, using a positive displacement pump and a gas pressure sensor to compensate for the varying liquid column length, ensuring accurate volume dosing by adjusting the pumped gas volume based on air cushion pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If no filling level sensors are provided for reservoir tanks, then device complexity and cost are reduced, but manufacturing precision of pumped liquid volume deteriorates due to unknown vertical liquid column length
Solution Approach 1:
A gas pressure sensor is introduced as an intermediary measurement device to indirectly determine the vertical liquid column length. The sensor measures gas pressure in the space above the liquid, which correlates to the liquid level, enabling volume compensation without direct liquid level sensing
Solution Approach 2:
The system changes the measurement parameter from direct liquid level detection to gas pressure detection. By measuring gas pressure and using it to calculate the vertical liquid column length, the system compensates for volume variations caused by changing liquid levels in the reservoir tank
2Ease of operation
If a fixed set volume is pumped without compensation, then ease of operation is maintained, but manufacturing precision deteriorates due to systematic overdosage from unknown liquid column effects
Solution Approach 1:
The gas pressure sensor provides feedback about the actual liquid column length to the control unit. The control unit automatically adjusts the pumped volume based on this feedback, maintaining ease of operation while eliminating systematic overdosage through closed-loop compensation
3Reliability
If worst case volume is pumped to compensate for inaccuracy, then reliability of dosage is improved, but loss of substance increases due to excessive process liquid consumption
Solution Approach 1:
The system dynamically adjusts the pumped volume parameter based on the measured gas pressure and calculated liquid column length. This eliminates the need to pump excess worst-case volume while maintaining reliable dosage accuracy, thereby reducing process liquid consumption
4Ease of manufacture
If systematic overdosage occurs, then ease of manufacture is maintained, but object-affected harmful factors increase due to photometric faults from process liquid color
Solution Approach 1:
The control unit adjusts the pumped volume parameter based on gas pressure measurements to achieve precise dosage. This eliminates systematic overdosage that causes photometric faults, maintaining measurement accuracy without complicating the analyzer's manufacturing
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 precise liquid volume dosing independent of the vertical liquid column length, reducing process liquid consumption and eliminating systematic photometric faults caused by inherent liquid color.
Implementation Method 1
providing a value of a pressure-adapted pumped gas volume which pressure-adapted pumped gas volume depends on the air cushion pressure effected by the effective vertical liquid column length
Implementation Method 2
the positive displacement pump directly sucks the pressure-adapted pumped gas volume of the air cushion having an air cushion pressure so that the exact set process liquid volume is indirectly pumped into the dosage chamber
Implementation Method 3
The higher the effective vertical liquid column length is, the more is the air cushion expanded by the weight of the liquid column hanging directly below the air cushion during the dosage pumping process step
Data Source
Figure 1
AI summary
The invention is directed to a process water analyzer (10) for automatically analyzing a parameter of a water sample, comprising a process liquid reservoir tank (70,72) with a process liquid (70',72'), whereas the process liquid reservoir volume (V70,V72) in the reservoir tank (70,72) defines a reservoir liquid level (170,172) at a reservoir liquid level height (h70, h72), a dosage chamber (30) fluidically connected to the process liquid reservoir tank (70,72) and being positioned fluidically downstream of the process liquid reservoir tank (70,72), and a positive displacement dosage pump (20) fluidically connected to the top of the dosage chamber (30) for sucking in the process liquid (70', 72') into the dosage chamber (30), whereas an air cushion (27) is always provided vertically between the dosage pump (20) and a dosage chamber liquid level (I) in the dosage chamber (30), so that a liquid column (Ic70, Ic72) with an effective vertical liquid column length (c70,c72) is given between the reservoir liquid level (170,172) and the dosage chamber liquid level (I), whereas the dosage pump (20) directly sucks a pressure-adapted gas volume (Vgas) of the air cushion (27) having an air cushion pressure (P) so that a set process liquid volume (Vliquid) is pumped into the dosage chamber (30), and whereas a process liquid dosage control unit (200) is provided, the process liquid dosage control unit (200) providing the value of the pressure-adapted pumped gas volume (Vgas) dependent on the air cushion pressure (P) effected by the effective vertical liquid column length (c70,c72).