TYPE OF EQUIPMENT:
V.O.C. (Volatile Organic Compounds) thermal oxidation system with recuperative thermal recovery.
The unit is mainly made up with a shell and tube heat exchanger and a combustion chamber equipped with a modulating burner. The gas containing V.O.C. is preheated passing through the shell and tube heat exchanger up to a temperature close to 450 ÷ 550 °C by mean of the heat released by combustion gases which pass through the shell side of the same heat exchanger, and then it passes through the combustion chamber where the modulating burner, which is normally fed with natural gas, supplies the amount of energy needed to reach and keep constant the temperature at which complete thermal oxidation of V.O.C. occurs and finally releases the heat absorbed, passing through the shell side of the heat exchanger, cooling itself down to a temperature bigger than the inlet one of 200 ÷ 300 °C and is emitted cleaned to atmosphere.
The gases’ residence time in the combustion chamber between 0,6 and 2 s at a temperature between 750 ÷ 950 °C, according to C.O.V. chemical composition, guarantees the complete thermal oxidation of organic compounds with oxygen to form carbon dioxide and water, with an efficiency up to 99,9% and a continuous emission level lower than 10 ÷ 20 mg/Nm3 of T.O.C. (Total Organic Carbon).
The efficiency of thermal recovery is normally in between 60 ÷ 70%, because of the high exchange surfaces required: for this reason an high consumption of auxiliary combustible is needed to maintain the combustion temperature, so that this type of technology is practically suitable only for little gaseous streams and high V.O.C. concentration or for those applications in which regenerative thermal recovery is not advisable because of high solid particulate concentration in gaseous stream to be treated.