Flow Field Analysis And Optimization Of Tail Flue Of 600MW Boiler

With the deepening of ultra-low emission operation,the emission standards of coal-fired boilers become more and more strict.At present,most coal fired power plants have reformed and updated the flue gas treatment equipment at the tail of the boiler.The internal flow field of flue gas treatment equipment at the tail of coal-fired boiler has an important influence on its removal efficiency,and it has become the key to the upgrading and updating of the tail gas treatment equipment.Therefore,it is of great practical significance to study the internal flow situation and analyze the causes of the flow field to make the corresponding reform scheme.In this paper,the SCR denitration system,the inlet flue of dust reduction and the desulfurization tower of a power plant are taken as the research object.First,the cold test of the SCR denitrification system and the hot test of the inlet pipe of the dust collector was carried out to preliminarily analyze the problems and effects of the internal flow field.Secondly,numerical simulation is used to simulate the SCR denitration system,the inlet flue of dust reduction and the desulfurization tower of the boiler.After verifying the accuracy of the numerical simulation by the test data,A detailed analysis is carried out to explore the causes leading to uneven distribution of flow field and to do research on optimization scheme.The main conclusions of this paper are as follows: in order to reduce the velocity of gas in reactor,the inlet flue of economizer outlet to SCR denitrification device usually needs to expend,and this expansion structure is the main reason for the uneven distribution of the flow velocity in width direction of the ammonia injection cross section.set a group of deflector plate at the expansion position can achieved a uniform distribution in the ammonia injection section.The structure and position of the rectification grid have an important influence on the flow field on the inlet of the first catalyst layer.The flow field of first catalyst layer entrance can achieve a uniform distribution by adjusting the position and structure of rectification grid appropriately.The asymmetric arrangement of the inlet flue of the dust collector and the excessive right-angle elbow will lead to excessive gas resistance and unequal distribution of flow in the chambers.The main flue is divided into two and the curved elbow is used to optimize the flow field.The uniform flow distribution plate can improve the flow field uniformity at the outlet of bell of the dust collector.For the bell that left and right expansion angle larger than the upper and lower expansion angle can use three layers uniform flow distribution plate with low open rate on middle and high open rate on both side.The spray slurry in the desulfurization tower can rectify the flue gas.The increase of the inlet dip angle of the desulfurization tower can prolong the travel of the flue gas in the tower and facilitate the full contact between the slurry and flue gas,but at the same time the tower resistance also increases.