Generator Cooling System Hydrogen Leak Detection
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Solution Overview
Problem
Large electric generators face challenges in maintaining stable copper oxide layers within cooling channels due to varying oxygen and CO2 levels in cooling water, leading to potential blockages and explosive gas mixtures, with existing systems lacking effective monitoring and control of gas compositions.
Innovation Solution
A system that continuously monitors and controls the injection of CO2-free air or pure nitrogen into the cooling circuit, measuring hydrogen leakage and CO2 concentration, and triggering alarms for critical levels, ensuring safe operation and preventing explosive mixtures by increasing the air injection rate beyond conventional limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If air is blown into the cooling water to increase oxygen content, then a stable copper oxide layer is formed, but CO2 is also introduced which acidifies the water and destabilizes the oxide layer
Solution Approach 1:
The harmful CO2 component is extracted and removed from the air before injection into the cooling water system. The patent employs CO2 removal devices (such as chemical absorbers or membrane separators) to separate CO2 from air, allowing only the beneficial O2 to be introduced into the cooling water, thus forming stable copper oxide layers without the detrimental acidifying effect.
Solution Approach 2:
The chemical composition parameters of the injected gas are changed by removing CO2 and adjusting the O2 concentration. The patent controls the O2 content in the cooling water to specific ranges (e.g., 2-5 ppm) while maintaining CO2 levels below critical thresholds, thereby optimizing the stability of the copper oxide layer without causing acidification.
2Stability of the object's composition
If the air injection rate is increased to ensure sufficient oxygen for stable oxide layer formation, then copper surface protection is improved, but the risk of forming explosive hydrogen-air mixtures increases
Solution Approach 1:
The patent implements a feedback control system with continuous monitoring of O2 and CO2 concentrations in the cooling water, as well as H2 content in the generator housing. Based on these measurements, the air injection rate is automatically adjusted to maintain optimal oxygen levels for oxide layer stability while preventing conditions that could lead to explosive mixtures.
Solution Approach 2:
The patent optimizes the air injection rate to specific ranges (e.g., 0.5-2.0 Nm³/h) and controls the O2 concentration in cooling water within safe boundaries (2-5 ppm). By precisely controlling these parameters, the system achieves stable copper oxide layer formation while maintaining hydrogen concentrations well below explosive limits.
3Device complexity
If CO2 removal is not implemented in the air injection system, then the system complexity is reduced, but the copper oxide layer becomes unstable and blockages occur
Solution Approach 1:
The patent extracts and removes CO2 from the injected air using dedicated CO2 removal devices. This extraction process, while adding some system complexity, is essential to prevent acidification of the cooling water and subsequent destabilization of the copper oxide layer, thereby ensuring long-term reliability of the cooling channels.
Solution Approach 2:
The patent introduces CO2 removal devices as intermediary components between the air source and the cooling water system. These intermediaries (chemical absorbers, membrane separators, or hydroxide solutions) selectively remove CO2 from the air stream, protecting the copper oxide layer from acidification while allowing O2 to pass through and maintain oxide layer stability.
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
This system ensures safer and more efficient cooling by maintaining stable copper oxide layers, preventing blockages, and reliably detecting hydrogen leaks, thereby avoiding explosive gas concentrations and ensuring consistent operation of large electric generators.
Implementation Method 1
The oxygen in the water reacts with the inner surfaces of these copper waveguides of large generators and a layer of copper oxide is formed on the walls of the cooling channels
Implementation Method 2
hydrogen molecules inevitably diffuse through the Teflon hoses into the stator's cooling water system
Implementation Method 3
CO 2 lowers the pH value of the cooling water and this then attacks the CuO layer, which means this layer becomes soluble and unstable
Implementation Method 4
The cooling water system must have a mechanism for degassing the water. This task is often solved with a tank in the main stream, which has a vent line to the atmosphere
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
According to the method, either CO2-free air or pure nitrogen N2 is pumped into the cooling circuit selectively depending on system parameters. To this end, the method ensures that the air injection rate is high enough that, under normal conditions, the hydrogen concentration in the tank and in the riser remains below 2% H2. On air injection, the oxygen O2 (>2 ppm) in the cooling water reacts with the copper in the cooling ducts and a layer of copper oxide forms on the inner walls of said ducts. No reaction is triggered by the injection of nitrogen N2. The CO2 content in the injection air and, at the same time, also the H2 content in the exhaust air are continuously measured and monitored, and an alarm is triggered if adjustable limit values are exceeded. The equipment for performing the method comprises an electronic control unit (65) with an input field and display as a control box, and a pump and a pipe circuit for drawing air in from the riser. The control unit (65) can evaluate all the measured data from the sensors and analysers connected to the pipe and can at least check the CO2 content in the supply air and the H2 content in the riser (13) and display the hydrogen leakage.