Sensor-Surface Deposit Detection with Dual Thermal Paths
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Solution Overview
Problem
Existing methods for detecting deposits and soiling on sensor surfaces in vessels or lines are unreliable due to changes in properties of the flowing medium, such as temperature, flow rate, viscosity, or concentration, and require additional space and complex setups.
Innovation Solution
A compact detection device with a thermally conductive main body and temperature sensors at different distances from the sensor surface, insulated by an enveloping body, allows for reliable detection of deposits and soiling by measuring temperature differences, independent of medium properties, without needing additional lines or active temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature sensors are arranged in an embossment on the outside of a pressure pipe to determine heat flow, then the soiling state can be identified, but reliable detection is restricted to operating points with temperature difference between inside and outside of the pipe
Solution Approach 1:
The detection device is segmented into two separate heat paths: a primary heat path through the pipe wall that is affected by deposits, and a secondary heat path through the thermally conductive block that is not affected by deposits. This segmentation allows independent measurement of total heat transfer and deposit-free heat transfer, enabling reliable detection across all operating points including those without temperature difference.
Solution Approach 2:
A thermally conductive block is introduced as an intermediary element to create a secondary heat path that bypasses the pipe wall. This mediator allows heat to flow through a controlled path that is isolated from the flowing medium, providing a reference measurement that is independent of medium temperature and flow conditions.
2Measurement precision
If a thermally conductive block with heating apparatus is used to create primary and secondary heat paths, then deposits on sensor surface can be identified by temperature difference, but inaccuracies arise when properties of the flowing medium change
Solution Approach 1:
The thermally conductive block is designed so that its sides are at the same temperature potential, creating symmetric secondary heat paths that are unaffected by the flowing medium. This equipotential design ensures that changes in medium properties do not create temperature gradients in the reference path, eliminating the source of measurement inaccuracies.
Solution Approach 2:
The thermally conductive block creates a copy of the heat flow path that mimics the primary path's geometry and thermal properties but is isolated from the flowing medium. This thermal copy provides a reference measurement that can be compared against the primary path to accurately determine deposit thickness independent of medium conditions.
3Measurement precision
If the same medium flows around all sides of the thermally conductive block to compensate for temperature changes, then inaccuracies are avoided, but additional lines are required and installation space increases
Solution Approach 1:
The harmful influence of the flowing medium is extracted from the secondary heat path by providing thermal insulation at the sides of the thermally conductive block. This extraction eliminates the need for additional medium flow lines while maintaining the reference measurement function, simplifying the overall device configuration.
Solution Approach 2:
Thermal insulation material is used to isolate the sides of the thermally conductive block from the flowing medium. This simple, inexpensive solution replaces the complex requirement for additional medium flow lines, achieving the same compensation effect with a passive, maintenance-free approach.
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
The device provides accurate and space-efficient detection of deposits and soiling, minimizing interference from medium changes and allowing for real-time monitoring and targeted countermeasures.
Implementation Method 1
a heat or cold source, arranged on the main body, for producing a primary flow of heat between the heat or cold source and the sensor surface and a secondary flow of heat between the heat or cold source and a reference surface
Implementation Method 2
an exterior insulation that insulates the enveloping body with respect to its exterior surroundings
Implementation Method 3
a first temperature sensor, which is arranged on the main body at a first distance from the sensor surface, and a second temperature sensor, which is arranged on the main body at a second distance from the sensor surface, the second distance being greater than the first distance, the temperature sensors being able to be used to ascertain a temperature difference
Data Source
AI summary
A detection device for detecting deposits and/or soiling on a sensor surface inside a vessel or a line containing a flowing medium, the detection device includes: a detection section; a thermally conductive main body; a heat or cold source arranged on the thermally conductive main body for producing a primary flow of heat between the heat or cold source and the sensor surface and a secondary flow of heat between the heat or cold source and a reference surface; a first temperature sensor on the thermally conductive main body at a first distance from the sensor surface, and a second temperature sensor on the thermally conductive main body at a second distance from the sensor surface; a thermally conductive enveloping body; the reference surface is part of the detection section, and the detection device includes exterior insulation that insulates the thermally conductive enveloping body.