Flow Cell In-Place Calibration Standard Addition
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Solution Overview
Problem
Traditional calibration methods for spectrometers and photometers in flow cells require disconnecting and reconnecting the sensors to a test rig, which is cumbersome and ineffective in continuous process streams, especially where access is difficult or risky, and may not accurately account for interfering materials.
Innovation Solution
A flow cell system that allows in-place calibration using standard addition techniques without removing the sensor from the process stream, incorporating a holder with a material standard that can be placed in the detector to calibrate the sensor by sequentially passing light through the process stream and the standard, eliminating the need for physical mixing and sample collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used requiring sensor disconnect and reconnect to test rig, then calibration can be performed, but device complexity and operation time increase significantly
Solution Approach 1:
The flow cell is divided into two separate chambers: a process stream chamber for continuous monitoring and a calibration chamber for standard addition calibration. This segmentation allows calibration operations to be performed independently without disconnecting the sensor from the process stream, resolving the contradiction between calibration accuracy and operational complexity.
Solution Approach 2:
A flow cell holder is introduced as an intermediary component that accommodates both the process stream flow cell and the calibration standard. The holder provides a unified mounting structure that allows sequential placement of process stream samples and calibration standards without requiring sensor removal, thereby maintaining measurement precision while simplifying the calibration operation.
2Measurement precision
If sensor is removed from process stream for calibration, then calibration can be performed, but loss of time and disruption to continuous process occur
Solution Approach 1:
The sensor remains continuously positioned in the process stream flow cell throughout both monitoring and calibration operations. The calibration chamber allows calibration standards to be introduced while the sensor stays in place, enabling continuous useful action without interruption to the process stream or loss of time.
Solution Approach 2:
Calibration standards are prepared and introduced into the calibration chamber before actual calibration measurements are taken. This preliminary preparation allows the calibration system to be ready for immediate use without requiring sensor removal or process disruption, thereby eliminating time loss.
3Ease of operation
If standard addition calibration is performed without accounting for interfering materials, then calibration is simplified, but measurement precision decreases
Solution Approach 1:
The calibration chamber is designed with specific local qualities: it contains the process stream sample and calibration standards in a controlled environment separate from the process stream chamber. This localized calibration environment allows interfering materials to be accounted for in the calibration process itself, maintaining measurement precision while keeping the operation simple through automated sequential sampling.
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
Enables continuous and accurate calibration of sensors within the flow cell, reducing the risk of contamination and sample alteration, and improving the accuracy of composition monitoring in continuous process streams by accounting for interfering materials without disrupting the process.
Implementation Method 1
Light passes from the input, through the first light window, through the first hollow internal volume, through the second hollow internal volume, and through the second light window before being detected by the detector
Implementation Method 2
The flow cells may be used with spectroscopic or photometric testing apparatus
Data Source
AI summary
A flow cell and flow cell system which allows for calibration of an attached sensor to be performed in place. Specifically, the ability to utilize standard addition techniques of calibration without the need to take a test sample from the process stream or remove the sensor from operating on the flow cell.