Desulfurization and Desulfurization Process of Liaoning Kiln and Its Characteristics

Although a variety of desulfurization and de selling technologies for Liaoning kilns have been developed, their process reliability and practicability still need to be verified. Therefore, some details of coke oven flue gas treatment technology need to be improved. Among many denitration technologies, selective catalytic reduction (SCR) is a relatively mature denitration technology with high denitration efficiency and wide application. SCR method is a method to selectively reduce NOx in flue gas to nitrogen and water under certain temperature and under the action of catalyst, using ammonia or hydrocarbon as reducing agent. The catalytic reaction temperature is 320-400 (the temperature range of coke oven flue gas is basically 180-300). This technology has no by-products. By increasing the load of catalyst, the denitrification efficiency can reach 80% - 90%.

1、 Necessity of Desulfurization and Desorption of Liaoning Kilns

1. Requirements for improving ecological environment quality: Coking industry is an important part of coal chemical industry, one of the important upstream industries of steel industry, and also a polluting industry. According to environmental protection statistics, in 2015, the emissions of sulfur dioxide and nitrogen oxides, the main pollutants in the coking industry, were 364700 t/a and 245800 t/a, respectively, accounting for 2.1% and 1.7% of the total industrial sulfur dioxide and nitrogen oxides emissions in China. Sulfur dioxide and nitrogen oxides in coke oven flue gas generated by coke oven heating are important sources of sulfur dioxide and nitrogen oxides in coking production. Due to long-term extensive development, the quality of the ecological environment has been seriously affected. The converted PM2.5 accounts for 40%~50% of the total PM2.5 in the air. At the same time, they are also the main substances forming acid rain, which will lead to a series of environmental problems. Therefore, it is an important task for the coking industry to control the generation of sulfur dioxide and nitrogen oxides and reduce the emissions of sulfur dioxide and nitrogen oxides.

2. Emission standard requirements: strict requirements are put forward for the emission concentration limits of various pollutants from the coke oven chimney: S0250mg/m3, NOx 500mg/m3, and the area where special emission limits are implemented is required to be S0230mg/m3, NOx 150mg/m3. According to the current domestic coke ovens,

2、 Characteristics of coke oven flue gas

The cleaned coal from the coal preparation workshop is transported to the coal tower through the coal conveying gallery, and then loaded into the carbonization chamber by the charging car through the nozzle of the coal tower, and carbonized into coke at a high temperature of 950-1050. The burnt waste gas passes through the cross hole, vertical flue and chute, conducts heat exchange with the checkered bricks in the heat storage chamber, passes through the branch flue and the main flue, and then is discharged from the chimney.

3、 Generally speaking, coke oven flue gas has the following characteristics:

1. The temperature range is basically 180-300 degrees, with a large fluctuation range;

2. The flue gas has complex composition and high NOx content. The concentration is generally 350mg/Nm3-1200mg/Nm3;

3. Containing SO2. Within the temperature range of 180~230, SO2 is easy to react with ammonia and convert into ammonium sulfate, causing pipe blockage and equipment corrosion;

4. Always be in hot standby. That is to say, after desulfurization and de selling of Liaoning kilns, the temperature after discharge should be kept at about 130 ℃.