Ceramic-Coated Thermal Expansion Probe for Boiler Corrosion Monitoring

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Solution Overview

Problem

Existing methods for installing electrochemical corrosion probes in boiler or heat exchanger walls are complex, require active temperature control, and can cause undesirable changes to the pressure parts of the boiler, making them difficult to install and potentially leading to incorrect measurements.

Innovation Solution

A cylindrical probe with a ceramic-coated fastening section that expands to create a press fit within the boiler wall's bore, allowing for simple and insulated attachment without complex temperature control, enabling thermal coupling and avoiding changes to the pressure parts, with a thermocouple for temperature monitoring and a shoulder for consistent installation depth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the probe is installed using conventional methods (welding or complex attachment), then the probe can be securely fixed to the boiler wall, but the installation becomes complex and requires changes to the pressure parts of the boiler

Engineering Contradiction:
Improvesecure fixationVSAvoidinstallation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The probe utilizes thermal expansion parameter changes to achieve secure fixation. The probe body is heated during installation to expand its diameter, allowing it to be inserted into the bore, then cools down to contract and create a press fit, eliminating the need for complex welding or attachment mechanisms

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention replaces complex mechanical attachment systems (welding, flanges, bolts) with a thermal-mechanical press fit system. The probe body itself becomes the fastening mechanism through controlled thermal expansion and contraction, simplifying the installation process and avoiding modifications to pressure parts

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If the probe is installed without thermal coupling, then the installation process is simpler, but the probe cannot achieve accurate corrosion measurements due to temperature mismatches

Engineering Contradiction:
Improveinstallation simplicityVSAvoidcorrosion measurement accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The probe body is designed to thermally expand when heated during installation, allowing easy insertion into the bore, and then contract upon cooling to create a press fit that ensures thermal coupling with the boiler wall, enabling accurate temperature-dependent corrosion measurements without complex installation procedures

Inventive Principle:
Principle #37Thermal expansion

Solution Approach 2:

The probe installation process utilizes dynamic thermal states - the probe is heated to expand for insertion, then allowed to cool and contract automatically, creating a self-adjusting press fit that ensures proper thermal coupling without requiring complex dynamic control systems

Inventive Principle:
Principle #15Dynamics

3Strength

If the probe body is made of metal for structural strength, then the probe can withstand installation forces, but the probe cannot be electrically insulated from the boiler wall

Engineering Contradiction:
Improvestructural strengthVSAvoidelectrical insulation
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The probe employs a composite structure combining a metal body (for mechanical strength and thermal coupling) with a ceramic coating layer (for electrical insulation). The ceramic layer is applied to the outer surface of the metal probe body, creating a composite component that simultaneously provides structural integrity and electrical isolation from the boiler wall

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The ceramic coating is applied locally to specific areas of the probe body that require electrical insulation, such as the outer surface and areas in contact with the boiler wall, while the metal body retains its full strength properties in all regions, optimizing both insulation and structural requirements

Inventive Principle:
Principle #3Local quality

4Object-affected harmful factors

If the ceramic coating layer is made thick for adequate electrical insulation, then the electrical insulation is sufficient, but the thermal coupling between the probe and boiler wall is reduced

Engineering Contradiction:
Improveelectrical insulationVSAvoidthermal coupling
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The ceramic coating thickness is optimized to a specific parameter range that balances electrical insulation and thermal coupling requirements, and the probe installation process utilizes temperature changes (heating for expansion, cooling for contraction) to achieve proper fit that ensures thermal contact through the ceramic layer

Inventive Principle:
Principle #35Parameter changes

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 solution simplifies probe installation, eliminates the need for active temperature control, ensures accurate thermal coupling, and allows for consistent measurement depth, preventing temperature mismatches and enabling reliable electrochemical corrosion measurements without altering the boiler's pressure parts.

Implementation Method 1

the coated fastening section in a cooled state has a first diameter which is smaller than the diameter of the web bore, and in the installed state after reheating has a second larger diameter such that there is a press fit between at least a part of the coated fastening section and the web bore

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the section located in the bore is designed as a fastening section for fastening the probe in the web and this fastening section is coated with a ceramic layer which electrically insulates the probe from the boiler wall

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Implementation Method 3

a thermocouple for detecting the probe temperature in the vessel and/or fastening section is arranged in the cavity

Methodology Applied
Scientific EffectSeebeck effect: Seebeck Effect

Data Source

PatentEP3146310B1Corrosion probe and method for installing a corrosion probe
Publication Date: 2018.03.28 STEINMUELLER BABCOCK ENVIRONMENT GMBH
  • EP3146310B1 patent drawingFigure 1
  • EP3146310B1 patent drawingFigure 2
  • EP3146310B1 patent drawingFigure 3

AI summary

The invention relates to a probe for electrochemical corrosion measurement on a boiler wall or heat-exchanger wall having a tube-web-tube design, which probe is cylindrical and has a segment to be accommodated in a bore in a web of the boiler wall. A simplified fastening mechanism and passive temperature control are provided by designing the segment as a fastening segment for fastening the probe in the web, wherein the fastening segment is coated with a ceramic layer, which electrically insulates the probe from the boiler wall, and the coated fastening segment has, in a cooled state, a first diameter that is less than the diameter of the boiler wall bore and has, in the installed state after reheating, a second larger diameter in such a way that there is a press fit at least between part of the coated fastening segment and the web bore.