Research On Abrasion Of DE-NO_X SCR Catalysts Applied To Coal-Fired Power Plants

With the improvement of environmental requirements, selective catalytic reduction (SCR) has become the most popular denitration technology in coal-fired power plant. In recent years, however, many catalysts in SCR systems are broken down, which seriously affecting the operation of the entire unit. Thus, research on the breakage of catalysts has important practical significance.The research object is about the breakage of catalysts in two coal-fired units. It’s mainly studied from the flue gas velocity and ash, which combining field tests and numerical simulations.Firstly, the field survey is conducted to comprehend whether there are special situations in SCR systems. Then, a field test is carried out to know the distribution of flow field, which can predict possible cause of breakage in catalysts. And it can provide basis for validation of the simulation results.Lastly, numerical simulations are carried out. After verifying simulation result by the field test result, fly ash is added to numerical simulations. According to the results of distribution of flow field and fly ash concentration from simulations, in-depth analysis on the breakage is formed.The main conclusions of the thesis are:the existence of anti-dust triangle structure above beam would break down the catalyst. Because a vortex would be formed by the plugging effect of anti-dust triangle structure, when the flue gas through the beam. Then the vortex makes flue gas velocity below the beam larger, which result in the breakage of catalyst. Besides, unreasonable layout of flue in SCR entrance and height difference above straightening grid would also break down the catalyst. Because flue gas would be turned into vortex by the existence of height difference. And unreasonable layout of flue would make the gas near the vortex larger. Finally, the velocity and ash concentration of flue gas three meters from the front wall are larger, which cause the breakage of catalyst.