Abstract: Uneven distribution of temperature on the same cross-section of a SCR (selective catalytic reduction) deNOx reactor results in an uneven distribution of concentration of NOx, which seriously affects the SCR deNOx effect. Further, the traditional uniform ammonia injection method fails to effectively address the problem of low removal efficiency and local ammonia slip. In this work, the SCR deNOx device of refinery self-provided boilers was studied. The partition ammonia injection technique was employed to improve the NOx distribution and diminish the ammonia escape in the case of non-uniform distribution of NOx concentration in flue gases at the inlet of SCR deNOx reactor. Compared with the uniform ammonia injection method, the partition ammonia injection makes NOx removal rate increase by 11.5 percent points, while ammonia consumption is reduced by 5 kg/h, and ammonia escape is declined by 77.5%. According to the estimation based on the relationship of temperature and concentration, if the difference of highest and lowest temperature in the same cross-section of the reactor inlet is more than 30 ℃ in the case of uniform ammonia injection，the partition ammonia injection method should be taken into consideration.

Key words: flue gas de-NOx, partition ammonia injection, NOx distribution, ammonia escape, denitration rate