Project Description:

Nanjing Jiangnan Environmental Protection Industrial Park MSW Plant Project was invested and constructed by Everbright Environment Energy (Nanjing) Co., Ltd. The project construction started in December 2012 with a total investment amounted to 1.052 billion yuan.The system was put into commercial operation in July 2014, and had a daily power generation capacity of more than 900 thousand kWh. The project could not only provide sufficient generation capacity for work and production in the power plant, but also support the urban electricity supply via the power grid.

In order to reduce the NOx concentration in the flue gas and to meet the flue gas emission standards, Everbright Jiangnan Project added SNCR+SCR denitration system. Techspray Environmental Protection Co., Ltd (STC) was responsible for the system design, the equipment supply, the installation guide for installation and debugging service in this project. STC provided four sets of SNCR+SCR system corresponding to the four 500 t/d waste incineration furnaces, including equipment, accessory equipment, the electric system and I&C system of the equipment. When the system was working, the NOx concentration would be reduced from 400 mg/Nm3 to 80 mg/Nm3. This system was the first SCR system that had been put into normal operation in the waste incineration power generation industry.

Process Design:

The SNCR + Low Temp. SCR denitration system for Nanjing Jiangnan Waste Incineration Project was mainly divided into three parts: the reducing agent storage and preparation system, SNCR system and SCR system.

The reducing agent storage and preparation system was distributed into the ammonia water tank and the ammonia still, which could provide the reducing agent for both SNCR and SCR system. The reducing agent was sprayed into the SNCR system, leading to redox reaction with NOx in the high-temperature region (850~950℃) in the furnace chamber. This could initially remove NOx and reach a denitration rateof about 50%. The SCR system adopted low temperature catalysts. The designed reaction temperature was 170℃. The mixture of ammonia and air was injected into the exit of the bag filter and was fully mixed with the flue gas in the flue. The mixture was assured to be evenly distributed before entering the reactor. In the present of the catalysts, redox reaction occurred between the mixture and NOx. In this case, NOx was removed once more with a denitration rate of 68%. The unite denitration rate of this SNCR+SCR system was 80%, which meant the outlet concentration of NOx was 80 mg/Nm3 or below.