At present, the domestic thermal power plant chimney corrosion in the relevant state departments in the absence of clear policy guidance, the use of titanium alloy plate, resulting in a serious waste of national strategic resources. Titanium is a rare metal, expensive, for the country's strategic materials At present, a large amount of 1.2 ~ 1.6mm thick titanium alloy plate composite material is used in the power plant chimney. Moreover, because the composite titanium alloy thin plate, rolling and composite process affected by impurities and penetrating or revealed, with such defects of titanium clad steel plate in the process of using in flue gas corrosion will appear serious "pitting" phenomenon (double electrochemical corrosion). At the same time, the scene combination, higher requirements on the welding process of titanium alloy plate, welding material and welding process directly affects the welding quality, technical level requirement for the welder is also very high, practical application often due to welding defects lead to corrosion of carbon steel inner cylinder base. Some understanding of the current situation of the chimney corrosion in power plant
The research Chinese electric power planning and Design Institute in 2009 through the 226 have desulphurization chimney, including six categories of 13 kinds of anticorrosion scheme. The results found especially in polyurea, Sa Weizhen, OM paint film coating and corrosion of the domestic foam glass brick chimney cracking, scour or shedding phenomenon is most serious. The problems were really accounted for about 90% of polyurea and Savi and domestic foam glass tiles accounted for 50%, accounting for about 40%, followed by OM coating glass flake accounted for about 25% of the acid resistant cement (mortar) accounted for about 20%; the acid liquid leakage by acid proof mortar masonry acidproof brick chimney is also very serious, accounting for about 20%. Although not all wet chimney, but the results reflect the feedback of China's current desulfurization chimney anti-corrosion engineering problems, involving a wide range, a higher proportion of leakage. Some of the project put into operation only 2 months and found that the foam glass brick to lead off the steel tube local corrosion and perforation; some desulphurization chimney renovation project put into operation after 4 months because of foam glass tiles cracking off, causing corrosion of reinforced concrete, resulting in some acid liquid along the outside chimney leakage. Many projects have just anti-corrosion transformation, running less than half a year, the chimney wall outside the obvious acid water leakage, corrosion of the chimney is too fast. The key is to wet chimney anticorrosion lining made of whole closed, with anti-corrosion materials for waterproof, leakproof, waterproof.
Because the coal source and composition of many and complex, corrosive medium in flue gas is very complex. The reliable titanium nickel alloy of wet chimney is not enough for some acid medium. Corrosion resistant materials are ceramic, glass and resin composite materials. Glass and ceramic type of anti-corrosion materials (paste foam glass brick and foam ceramic tiles, etc.) can not be large, in the integrity and tightness of the problem is more serious. Glass fiber reinforced plastic composite material can meet the requirements of a variety of functions and working conditions. It is the preferred material for chimney anticorrosion engineering. The use of composite materials instead of Ti Ni alloys is a trend. As with many of the technology, the composites were first used in the aerospace and military fields, and then turned to civilian areas.
In the scientific and technical problems in the field of composite materials, the contradiction between the efficiency and reliability of material structure is the most difficult to solve. Like many materials, it is difficult to balance the high efficiency and high reliability of the composite structure. The dispersion of performance and uncertainty of service environment are the most important problems in the application of composite materials and structures. Since 1980s, our country has carried out the research of composite materials, but it has restricted the development of composite material industry due to the weak basic research and the lack of original technology. Some understanding of the current situation of the chimney corrosion in power plant