| Reducing the flue gas temperature of coal-fired utility boilers can improve the boiler efficiency and reduce coal consumption.But the low temperature corrosion will occur when the flue gas temperature is lower than the acid dew point.It has always been a difficult problem to predict the acid dew point accurately in academia and industry.In this paper,the calculation method and related experiment of acid dew point are conducted.There are many factors affecting acid dew point of flue gas,and the mechanism is complex.The concentration or partial pressure of sulfuric acid in flue gas is the most direct factor of the flue gas acid dew point,and the reaction product of water vapor and sulfur trioxide in flue gas is the main source of sulfuric acid vapor in the flue gas.The remaining factors,such as excess air coefficient,ash,sulfur dioxide,etc.,mainly affect the value of acid dew point by affecting the concentration and partial pressure of sulfur trioxide.Ten empirical formulas for calculating acid dew point are summarized in this paper.Formulas are calculated under the conditions of 800 Pa and 9% water vapor volume fraction.At the same time,the calculated results are compared with field measurements at home and abroad.The results show that the numerical distribution of P.А.Леpoeян is relatively reasonable.Haase&Borgmann formula is more suitable for the low sulfur trioxide content condition,while И.A.BapaHoB formula is more suitable for the high sulfur trioxide content.When the sulfur trioxide content is lower than 35 ppm,the calculation accuracy of Haase&Borgmann and P.А.Леpoeян formula is higher than И.A.BapaHoB and other formulas.In order to verify the correctness of the theoretical analysis,the test device of flue gas dew point was designed and built in this paper,which is based on the one-dimensional furnace combustion system.The above analysis results were verified by experiments then.And the P.А.Леpoeян formula was modified based on the analysis of the test results.It is perceived that the P.А.Леpoeян formula has higher accuracy according to the measurement data of domestic related scholars when the sulfur trioxide content is lower than 35 ppm.In order to further analyze the calculation accuracy of the modified formula,the selfdesigned measuring device of flue gas dew point and the engineering acid dew point measuring system jointly produced with Guangdong Electric Power Research Institute were used to conduct field test research.Then the theoretical analysis of the measured data was carried out by the modified formula and several formulas.The results show that the modified formula has higher calculation accuracy than the common calculation formula of acid dew point,and the error is less than 4.5 °C.Compared with the experimental results,using the theoretical value of the formula as the limit temperature of boiler exhaust,and the utilization rate of waste heat in boiler tail could be improved. |
PDF Full Text Request