Oxide of Nitrogen
Most oxide of nitrogen at SCG occurs in the cement manufacturing process from combustion inside the kiln which requires a temperature of up to 1,000 °C and the nitrogen molecules in the fuel which reacts to the oxygen during combustion.
SCG has joined the World Business Council for Sustainable Development-Cement Sustainability Initiative (WBCSD-CSI) and is determined to control the oxide of nitrogen emission to below 1,700 grams per ton clinker. This requires highly efficient technology, thus, every cement plant at SCG is fitted with the Low NOx Burner which decreases the emission. Moreover, SCG has adjusted the Preheater Cyclone and Calciner system to enhance combustion efficiency. This helps to control the proper fuel and air ratio during combustion and reduce excess air to minimize nitrogen and oxygen reaction.
Maptaphut area in Rayong province also highlights oxide of nitrogen emission as power plants and chemical manufacturers with high-temperature combustion are located in the area. SCG Chemicals is mindful of the necessity to reduce emission, especially in the cracker furnace unit. SCG Chemicals has installed an Ultra-Low NOx burner that can reduce oxide of nitrogen emission 80% better than typical burners, thus, reducing energy consumption. SCG Chemicals requires that Ultra-Low NOx burners are used in all of its chemical plants as a minimum requirement which is stated clearly in the factory blueprint.
Additionally, SCG Packaging has installed a highly efficient boiler which can stabilize the combustion temperature. This also contributes to the decrease of the oxide of nitrogen emission.
Oxide of Sulfur
Oxide of sulfur is the main cause of acid rain. 90% of it is produced in the manufacturing process from fuel combustion, especially with coal which contains sulfur. The cement business has limited sulfur dioxide (SO2) emission from exhaust stacks with reference to the WBCSD-CSI agreement at 120 grams per ton clinker. This is executed by installing a calciner to help decrease emission.
SCG Packaging uses coal as the main source of energy to provide heat for the boilers. Therefore, SCG Packaging initiated measures to reduce sulfur dioxide emission by controlling the whole process. This begins with selecting high-quality coal with low sulfur, increasing the portion of waste reject usage derived from waste paper, and using biogas from the anaerobic wastewater treatment to substitute coal. Moreover, polluted air is treated before release to the environment by adding limestone which becomes gypsum that can be reused in the cement manufacturing process.
Particulate Matter contributes greatly to the substances generated from the cement manufacturing process. It occurs in the raw materials grinding process, combustion and reactions, clinker grinding, packaging, and the transportation of the raw materials and cement.
SCG joined the WBCSD-CSI as an attempt to control dust particles emitted from the stacks to be less than 150 grams per ton clinker. This involves installing efficient technology to limit the emission to be within the stated target. Measures include installing high-performance dust collector using electrostatic and filter bags that can increase performances to 99.9% as well as designing a closed-system building, machine, and conveying structure to prevent spreading outside of the working area.
Volatile Organic Compounds (VOCs)
The petrochemicals industry emits Volatile Organic Compounds or VOCs from the raw materials and the by-products. VOCs that affect the health of exposed individuals are Benzene, Toluene, Butadiene, and other substances that may pollute the earth’s ozone leading to respiratory infections.
SCG Chemicals explored and identified the source of VOCs in different units such as the raw materials storage tank, material and product transportation process, waste water management system, and by-product from combustion. Afterward, SCG Chemicals enhanced processes to minimize spreading and leakage of the VOCs. This includes closed-system plant design, upward product conveyors, enclosed waste water management system, checks and repairs of joints, valves, and other parts of the pipes, sealed sampling collecting unit, seamless pumps, and roofed naphtha tanks which provided over 30% better control for the spread of VOCs when compared to international standards. This effort has made SCG a role model for VOCs management in related industries.
Mercury is created from the cement manufacturing system mainly from raw materials and fuel used in the process. Therefore, the amount of mercury emission relies greatly on the portion of raw materials as well as the type and source of the fuel.
SCG Cement-Building Materials has announced internal criteria regarding mercury emission and has controlled the quality of industrial waste, renewable raw materials, and fuel in the kilns.
In SCG’s cement plants, mercury emission is monitored to be within legal standards with at least 2 investigations per year. Moreover, data on mercury emission is reported in the Environmental Impact Assessment or EIA report. Additionally, SCG has joined the World Business Council for Sustainable Development-Cement Sustainability Initiative (WBCSD-CSI) as an attempt to control emission and meet the global standard of leading cement plants worldwide.