High Temperature Corrosion Protection Of Boiler Water-wall And Reduce NOx Emission With Sidewall Air-blowing Technology

The high-temperature corrosion of the water wall tubes in coal fired utility boilers will result in serious problem of shutdown and safety. In China, high-temperature corrosion has been found in most of the coal-fired utility boilers, and resulted in enormous loss. It was found that the high-temperature corrosion was mostlydue to the exist of H2S in the gas, and which mainly comes from the iron- pyrites-sulfur in the coal. In our study a sidewall air-blowing technique has been developed to avoid the high temperature corrosion..The main idea of the side-wall air-blowing technique isto install a set of nozzles on the water-wall which are far from the main burners and just on the upstream to the area where high-temperature corrosion exists.The fresh air injected from the side-wall air-blowers will cover the corrosion area and form a protective layer blocking off the corrosive gas, so the water-wall tubes will be protected.The low NOx combustion technology has also been studied in this thesis. The NOx is among the most serious pollutants from the coal-fired boilers, resulting in domestic pollution and acid rain. With more stringent NOx emission regulation, there is an imperative necessity for China to develop a suitable de-NOx technology. The sidewall air-blowing technology can reduce the NOx emission effectively. In sidewall air-blowing system, the secondary air has been feed to the furnace at the downstream of coal-powder flow, formed staged-air combustion in both vertical and horizontal direction, reduced the NOx formation.