Recently, the renovation project of Shandong Nicest Carbon Black Co., Ltd. for desulphurization and denitration of the original carbon black tail gas boiler and drying oven has been put into operation.

This renovation project is to newly equip and build a set of desulphurization equipment for both 260,000m3/h smoke from 2×35t/h boiler and 90,000m3/h discharged from carbon black production line by adoption of domestic advanced low-nitrogen combustion + SCR combined denitration and limestone-gypsum wet desulphurization scheme.

As desulphurization absorber in the desulphurization system, the limestone flour is made into 30% slurry of absorption after mixing with water and stirring. When the upstream SO2 in smoke touches the top-down slurry of absorption in the absorption tower, the SO2 will be desorbed after reacting with calcium carbonate of the slurry and oxidation air. The final reaction product is gypsum. The desulphurized smoke will be discharged from the chimney at the top of the tower after removal of small droplets through demister. The desulphurization gypsum slurry goes through two levels of dehydration and slurry of absorption is recycled, thus the desulphurization absorber has high utilization efficiency. The whole set of technology includes smoke system, absorption cycle system, oxidation air system, absorber supplying system, process water system, maintenance and empty system, etc.

The denitration technology refers to low-nitrogen com- bustion + SCR combined denitration system. By using of low-nitrogen combustion device, the feeding of fuel and wind to every burner and overfire air spout can be accurately controlled so as to achieve sufficient burning, further improve the percent reduction of NOX and reduce the discharge of NOX. In addition, the 20% ammonia solution will be injected into the ammonia evaporator by injector via ammonia dilution device and distribution device. Then the atomizing ammonia solution will be decomposed adiabatically by hot primary air of 300°C boiler in the plant, resulting in NH3 and H2O steam. The decomposition products and the hot primary air of 300°C boiler enter into SCR ammonia injection system after uniform dilution and mixture (concentration < 5%). Under the action of catalyst of SCP system, with the reducing agent of NH3, the NOX in smoke will be turned into innocuous N2.