Study On Corrosion Characteristics Of Convection Heating Surface Of Coal And Biomass Co-combustion Boiler

Energy conservation is one of an important issue for the sustainable development of our country, biomass as a carbon based renewable energy, can be conveniently and Coal Co firing. However, the problem of the corrosion of convection heated surface has been limited to the promotion of the technology of biomass and coal blending.Dawa County, Panjin, a heating company a 80 tons of heating boilers, the original design of the fuel for class Ⅱ bituminous coal, after blending local corn straw pressing block, resulting in a serious corrosion problems. It was demonstrated that adding biomass will lead to fouling, chlorine corrosion, corrosion of the heating surface will increase. There is also literature that adding an appropriate proportion of biomass, SO2 in flue gas can inhibit chloride corrosion, and high temperature is obvious. According to the practical engineering problems and literature research results. Main work of the thesis is three aspects:of biomass and coal CO combustion corrosion mechanism in the process of research and analysis, secondly to determine the corrosion factors. Finally, the proposed corrective recommendations.First, we need to simulate the actual environment, and carry out laboratory tests. Provide experimental materials for boiler factory of 20G steel; corrosion surface temperature, according to the measured and fluent software simulation determined to 450℃, at a temperature of 500℃,550℃ and 600℃; according to the furnace tube surface sediments of the XRD analysis results to determine the corrosion KCl:NaCl:K2SO4:Na2SO4=63:13:5:1; root according to furnace flue gas to form principle to determine the Cl2, O2 and SO2 gas influencing factors. According to the standard of flue gas, with 10%H2O and 12%CO2. For the rest of the N2.Then a test system was set up, and the corrosion weight gain method was used to carry out the research. Test is divided into three aspects:one is alone burning biomass alone coal and biomass mixing three kinds of comparison and coal combustion; the second is of different temperatures, corrosion characteristics of boiler steel and corrosion resistance ability of them was studied; the third is by using the orthogonal experiment method, the research of Cl2, O2 and SO2 effects.The main conclusions are as follows:1. Biomass and coal blending certain conditions will aggravate corrosion; 2. S., Cl, O three factors in the corrosion reaction, the important degree respectively CL>S>O; 3.The 20G steel under different temperature corrosion reaction rate and reaction temperature exponentially. At 450℃ and 500℃, also has a certain ability to resist corrosion, corrosion resistance at 550℃, the ability to gradually weaken, at 600℃, the total loss of corrosion resistance.4.The effect of O2 concentration on corrosion in biomass boiler can not be ignored.According to the conclusion, the boiler is put forward as follows:1 Corrosion protection coatings are considered in the area of increasing corrosion to reduce the ratio of straw biomass fuel in mixed fuel.2. It need to control the furnace outlet O2 concentration, improve the furnace mixing capacity.