Research On Online Monitoring System For The Corrosion And Oxidation Process In Thermal System Of Ultra-supercritical Unit

As people’s demand is growing, thermal power unit gradually tends to large capacity and high parameter. Ultra-supercritical unit will be the trend in China for saving energy, improving the environment reducing the cost of power generation, and improving the power generation efficiency. With the improvement of the steam temperature and pressure, the efficiency of the boiler increase significantly, and the coal consumption for power supply decrease. But we also meet some technical problems, especially the high temperature corrosion resistance and high temperature steam oxidation resistance of the material. And the increasement of the steam parameters will fasten the metal oxidization of the components in boiler, such as superheater and reheater. How to reduce and inhibit the formation of oxide skin peeling effectively become a big problem for the safe operation of ultra-supercritical unit. Therefore, further study of the oxide skin problems, has a important theoretical value and practical significance for security, stability and economic operation of the unit. The corrosion will happen in the metal surface in high temperature water and high temperature steam, and there will produce trace amounts of dissolved hydrogen. We reduce and avoid thermal system corrosion and oxidation by monitoring dissolved hydrogen content. In this paper, by measuring the dissolved hydrogen content in steam system of power plant boiler, we monitor the corrosion and oxidation process in thermal system online and study the law of high temperature corrosion and oxidation of metal materials. This topic is mainly to solve the real-time monitoring of corrosion and oxidation in the thermal system, make the on-line monitoring system for the corrosion and oxidation process in thermal system become simple and practical. Because the online hydrogen monitor’s accuracy is 1 ppb at least, we can monitor timely if corrosion and oxidation happen in the thermal system. We can observe the operation condition of the unit in real-time in Chaozhou and Lvsigang power plant by a new online hydrogen monitor. Through the analysis of the collected data, we can estimate the various factors affecting hydrogen content and optimize the unit operation index.