Effects of thermal disposal of oil-water residues on operation heating plant boiler

Abstract

Industrial zones are often the source of specifically polluted waters, depending on type of industry. These waters are usually not in the limits for outtake into public sewers and it is necessary to dispose them externally or build-up technologies for their pre-treatment. The article is about the real case of an industrial. A separate sewage network is built for oily water. Solid impurities are separated from the oily water and oily water is treated by evaporation technology. The evaporator produces two types of products - condensate and concentrate. Condensate is a water with high organic content, and it is necessary to purified it by a chemical treatment plant in next step. Evaporator technology remove from water the most of metal content and significantly decrease organic and water content in concentrate. Concentrate is oily stream with lower water content. Water content in concentrate decreased in next technology steps to ca. 40-50 %. The final product is certificated technological fuel, and its final elimination is in the heating plant fluidized bed boiler. The article is detailed focused on the influence of concentrate combustion. A local temperature increases around 10-15 °C extending across the combustion chamber was confirmed. There was also an increase in HF concentration in flue gas. CO concentrations were higher in the first moments of combustion, but the control system responded by increasing the combustion air supply, and CO concentrations were finally lower at the level of 3 mg·m-3. During combustion, there was no provable increase in concentrations of NOX or other substances, and the co-combustion did not have a significant effect on the operation of the boiler, so this way was evaluated like technically and economically effective.