Container Inner Coating Damage Detection via Electrical Resistance
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Solution Overview
Problem
Existing methods for detecting damage to the inner coating of containers, especially those with conductive process liquids and metallic walls, face challenges such as electrolysis interference, complex resistance measurements, and the influence of parallel resistances, making it difficult to reliably and cost-effectively identify lining damage.
Innovation Solution
A measuring arrangement that measures electrical variables like insulation value or resistance, using commercially available devices like earth testers and ISOMETERS, to detect damage by monitoring changes in current paths and voltage drops, allowing for the identification of damaged coatings through multiple measurement points and system connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measuring voltage is applied between the conductive container wall and an electrode in the conductive fluid to detect inner coating damage, then damage detection is enabled, but electrolysis occurs which influences the measurement result and may damage the coating
Solution Approach 1:
The patent applies periodic measuring voltage pulses instead of continuous voltage to minimize electrolysis. The measuring arrangement generates voltage pulses with a frequency of 1-1000 Hz, where the coating is only subjected to voltage during the pulse duration. This periodic action allows damage detection while significantly reducing cumulative electrolytic damage to the coating.
Solution Approach 2:
The patent changes the electrical parameters of the measuring voltage, specifically using very low voltage levels (0.1-10 V) and limiting current density to below 1 µA/cm². By adjusting these parameters, the measurement becomes sufficiently sensitive to detect coating damage while remaining below the threshold that causes significant electrolysis.
2Reliability
If the container wall is grounded for lightning protection, then lightning protection is ensured, but parallel resistance paths are created that complicate resistance measurements for damage detection
Solution Approach 1:
The patent segments the measurement system into distinct functional components: the measuring arrangement with pulse generator and measurement electrode, the container wall with its lightning protection grounding, and the conductive fluid. By segmenting the measurement current path and using differential measurement techniques, the system can distinguish between current flowing through coating damage versus current flowing through parallel paths via the grounding system.
Solution Approach 2:
The patent introduces a non-conductive pipeline section as an intermediary element between the measurement electrode and the container. This intermediary allows the measurement current to pass through the conductive fluid and reach the container wall without creating additional parallel resistance paths, effectively isolating the measurement circuit from the grounding system's influence.
3Measurement precision
If multiple measurement points and system connections are used to account for parallel resistances, then measurement accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent designs the measuring arrangement to perform multiple functions: it can measure resistance at different locations along the pipeline, detect coating damage, and compensate for parallel resistance paths using the same basic hardware configuration. The measuring arrangement includes a pulse generator, measurement electrode, and evaluation unit that can be positioned at various points in the system to achieve accurate measurements without requiring multiple specialized devices.
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 simple, reliable, and cost-effective detection of inner coating damage, reducing the risk of electrolysis and accounting for parallel resistances, thereby ensuring timely identification and mitigation of potential container threats.
Implementation Method 1
measuring arrangement (18) for measuring an electrical quantity, in particular insulation value or insulation resistance
Implementation Method 2
the pipeline and the container are at least partially filled with an electrically conductive process fluid
Implementation Method 3
container wall has an insulating inner coating made of plastic
Implementation Method 4
the current flow from the process fluid to the container wall can then ideally only occur via the damaged lining
Data Source
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AI summary
The invention relates to an arrangement and to a method for detecting damage to an inner coating of a container, by means of which simple, reliable, and economical determination of damage is made possible. To this end, a measuring arrangement has been devised which, firstly, is influenced by damage to the inner coating (rubber covering damage) and/or actuation of plant parts (shut-off valves) and/or by electrical changes in the current paths in the measuring arrangement, in such a way that the latter generates a reproducible signal excursion which, in turn, can be assigned to the respective activity and therefore to the corresponding parts of the plant, such as a container (1 a-d). Thus, by means of the measuring arrangement, both slowly changing values, which arise as a function of process-induced slowly changing process parameters, such as temperature, concentration, conductivity, and other gradually occurring damage to an inner coating, and also short-term significant changes of values are detected, which are brought about, for example, by pumping operations or by connecting together plant parts, which influence the electrical properties of the system. Said detected signal excursion is interpreted appropriately.