The mixing homogeneity of reductant and flue gas has significant influence on denitration efficiency and amount of ammonia slip in selective non-catalytic reduction(SNCR) denitration technology. The long spraying gun of the SNCR denitration system has a wide spray coverage and is suitable for application in large zone of the boiler. The long spraying gun shows a cantilever beam structure when working in the furnace of boiler

so it is necessary to evaluate the stress and deformation for its heavy weight. By the finite element method(ANSYS)

the structural deformation and Von Mises equivalent stress of 6～11 m spraying gun at cold state are analyzed. The heat transfer method is used to obtain the inner and outer wall temperatures of the outmost shell of the long spraying gun

then the thermal stress around the small hole of the long spraying gun is investigated. The result shows that

the length of the long spraying gun should be shorter than 8 m to ensure its safe operation in the boiler.