CEMENT FACTORY EXHAUST GAS TREATMENT

What is the composition of cement factory emissions? And their harmful effects?

The main air pollutants from cement factory emissions are dust, CH₄, VOCs, NOx, SOx, CO and CO₂..

It is the cause of global warming, and also a factor harmful to human health. It has adverse effects on air, water and soil.

Decreased growth rate of plants due to pollutants released into the environment. It also changes thechemical composition of the soil. Pollutants settle into water, harming aquatic life. For humans, it causes respiratory diseases, eye and skin irritation, etc. Long-term exposure can be a factor in causing cancer.

Sources of components of cement factory emissions

Cement production process

Exhaust gases in cement factories include two main components: dust and pollutants. strong>

They arise in the production process from raw material extraction to finished product packaging. There are also emissions from transportation and fuel used.

CO₂ is produced during the production of clinker, a component of cement.

Specifically,limestone (CaCO₃) is heated in a rotary kiln at a temperature of 1,000°C. CO₂ is a byproduct of the calcination process.

Half of the CO₂ in the exhaust gas comes from the calcination process, the other half comes from the fossil fuels used to heat the furnace

Substances that cause air pollution include SOx and NOx also arises from the kiln and drying process. SO₂ is created from sulfur compounds inores and burned fuels. The process of burning fuel in cement rotary kilns produces NOx from nitrogen in the fuel and air.

Compounds of volatile organic substances (VOCs) ) arises from gasoline, stored solvents, and other industrial chemicals.

Incomplete combustion of organic fuels is also a source of VOC emissions into the air.

Dust generated originates from the process of exploiting, transporting raw materials, crushing and screening raw materials, and roasting raw materials at high temperature, packaging and transportation of finished products. Dust particles have different sizes and spread through the air, spreading far away.

Cement factory exhaust gas treatment process

The process ofexhaust gas treatment of a cement factory can be divided into three stages as follows:

Phase 1: Treatment of NOx in cement exhaust gas

Before the flue gas leaves the rotary kiln, to remove NOx use the SNCR method. How to proceed, the solvent is pumped from the tank to the nozzles, the fog solvent is sprayed directly into the exhaust gas stream.

The most commonly used solvent to remove NOx is Ammonia (NH₃), or Urea  [CO(NH₂)₂]. The final product of the reaction is N₂ which has no harmfuleffects on humans and the environment.

Phase 2: Dust treatment in cement exhaust

Air containing dust is sucked into the cloth bag dust filter. Here, the gas and particles will lose their velocity, leading to high density particles falling to the bottom.

Smaller dust particles will stick to the surface of the filter bag. The process of cleaning the filter bag involves shaking the bag.

Dust particles clinging to the surface of the bag fall to the bottom. The trapped dust will be recovered back into the production process

Phase 3: Treatment of SOx and remaining pollutants in cement factory emissions

The gas flow that passes through the dust filter will be directed to adsorption tower with multiple layers activated carbon. SO₂ gas and remaining pollutants will be trapped in the activated carbon layer, the clean gas is led to the atmosphere. After a period of use, activated carbon will be saturated, at which point the charcoal will be reconstituted.

Factoryexhaust gas treatment system cement