The causes leading to ash deposition in flue gas denitrification system for 2×630 MW units in Shenhua Guohua Taicang Power Generation Co Ltd

such as foreign matters in fly ash

moisture absorption and hardening of ash deposition

peeling off of oxidized skin from structural members etc.

have been systemtically analysed

pointing out the facts as follows:ash deposition is easily occurred on upper and bottom surface of catalyst

and in area of the cross beam

severe ash deposition will cause pressure difference in the sytem to increase

and making the catalyst to lose efficacy too early.Finally

a method of cleaning the ash deposition by using vacuum extraction and problems needing to pay attention in operation of the system have been given.