In order to solve the problem of large thermal deviation of 700 ℃ tangentially fired boiler

numerical simulation is carried out by using Fluent 16.0 software. With thermal deviation of furnace outlet section as the optimization index

three factors

such as anti-tangential angle of over fire air(factor A)

velocity offset of over fire air(factor B)

and the interaction between factor A and B(factor A×B)

are optimized at three levels. Range analysis method and weight matrix analysis method are applied to determine the best combination of the above three factors and levels and the specific weight proportion. The results show that

the importance degree of each factor to the thermal deviation of the outlet section of the furnace is as follows: anti-tangential angle of over fire air over fire air velocity offset the interaction between anti-tangential angle of over fire air and over fire air velocity offset.The weight proportions of factor A

factor B and factor A×B is 0.875

0.079

and 0.046. Through two analysis methods

it is concluded that the interaction between anti-tangential angle of over fire air and over fire air velocity offset can be neglected. The best factor and horizontal combination of the orthogonal test is A3B3. In this combination scheme

the anti-tangential angle of over fire air is 25°

the over fire air speed ratio(right side/left side)is 0.77

and the thermal deviation of the outlet section of the combined furnace is 28.405 K

which is 89.01 K lower than the highest thermal deviation

with a significant decline.