Abstract: Considering the problem that the dust collector could not be put into operation due to the large amount of ammonia escaping from the denitrification system,the optimization adjustment of ammonia injection in vortex mixer SCR denitrification system was carried out. It is found that the NOxconcentration in the denitration outlet is unevenly distributed in the width direction. By adjusting the manual butterfly valve of the ammonia injection branch pipe,the non-uniformity of NOxconcentration in the denitration outlet is reduced. At full capacity,the inhomogeneity of A side of the flue decreases from 48.3% to 19.4%,the inhomogeneity of B side decreases from 62.7% to 21.8%. After adjustment,the NOxdistribution inhomogeneity decreases significantly. There is no obvious deviation of flue flow on both sides under high and low load. The distribution of flow field is relatively uniform. A new type of eddy current static mixer was adopted whcih was helpful to solve the problem of uneven distribution of NOxconcentration in the outlet of denitration along the depth direction. It is found from the SIS data that the CEMS measuring point of NOxconcentration at denitrification outlet is inaccurate,which leads to the excessive amount of ammonia spray and the large amount of ammonia escape during automatic operation of ammonia injection. The measuring point of CEMS is not representative,which is recommended to use grid sampling method. A regular calibration of CEMS measuring points is recommended.The poor following performance of ammonia spray causes a certain delay between the ammonia spray and the NOxconcentration at the denitrification inlet in control strategy of ammonia injection. The ammonia spray control logic should be optimized. The NOxemission concentration of net flue gas should not be set too low. The lower the setting value is,the greater the ammonia escape amount is. Considering the environmental requirements and economy,it is recommended that the net flue gas NOxemission concentration is controlled within 25-35 mg/m3. After the ammonia injection optimization,the overall ammonia escape is controlled below 3×10-6.