Two denitration reactors are provided for each unit. To ensure a favorable reaction environment and adequate reaction time in the reactor, a flue gas rectification device of reliable performance is provided at the inlet of the reactor, and the flue gas velocity is kept at about 5 m/s. Three catalyst layers are provided in the reactor, of which two layers are for normal operation and one layer is for standby. A plate or honeycomb catalyst is adopted with necessary soot blowing device provided. The dimensions of the reactor are determined based on the flue gas flow & velocity under 100% BMCR operating conditions as well as the performance and module dimension of the catalyst. In this project, the section of a single SCR reactor is rectangular, with a sectional dimension of 12 × 15 m. Two reactors are provided for each boiler.
While flue gas passes through the reactor, NOx and NH3 react to produce N2 and H2O under the effect of the catalyst. The catalyst, however, is not consumed during the reduction reaction. But with the operation continuing on, the catalyst activation declines. When NOx removal efficiency and ammonia slip cannot meet the requirement, the standby catalyst layer shall be put into service or a new catalyst layer shall be applied.
The more uniformly the flue gas flow velocity field, temperature field and reactant concentration (NH3/NOx molar ratio) are distributed in the flue, the more guaranteed the NOx removal reaction efficiency is. Our company makes numerical calculations on the flow field, temperature field and concentration field of the flue gas by using an advanced computer fluid analysis method and simulates the actual situation to optimize the denitration reactor’s performance. Our company has accumulated rich practical experience in the experimental design of airflow distribution in the dust precipitator,has got rich design experience and can guarantee outstanding performance. To obtain reliable performance, in light of experience, the maximum deviation of flue gas velocity distribution on the section at the inlet on the top of the reactor should be under 10%~15%, the maximum deviation of flue gas temperature distribution under 10~15°C, and the maximum deviation of NH3/NOx molar ratio distribution under 5%~10%.
The reactor is designed to have the flue gas flow downwards vertically. A splitter is provided at the inlet and outlet section of the reactor, and an expansion joint is provided to absorb three-dimension expansion.
Manhole doors of adequate size and number are provided for the reactor, including an access door for the replacement of the catalyst.
An access platform of adequate size is provided for maintenance and replacement of the catalyst and the soot blower near the reactor, along with the monorail and motor hoist required for lifting, erection and replacement of the catalyst.