Treatment system for the elimination of odours in a gaseous stream of asphalt bitumen

Identifier:  TFG:2424

Handle: https://hdl.handle.net/20.500.11797/TFG2424

Authors:  Martín Clopés, Ignacio

Abstract:
The following project is created to achieve total elimination of odor and smell emitted by ASESA’s bitumen storage tanks. ASESA produces 1 million tons of bitumen annually, a quantity which would allow the construction of 5500 km of a two-lane road. And with a refining capacity of 1,4 million tons of crude oil, the amount of product that ASESA needs to store is substantial. This poses the necessity of creating product storage facilities. In the case of bitumen, the storage facility is a tank yard in which the largest tank has a storage capacity of 30 thousand tons of bitumen. The bitumen storage tanks are open to the atmosphere (API tanks) and therefore can release gases into the atmosphere. For example, during the filling of the tanks the same amount of volume of product being fed into the tanks is displaced in the form of gases from the head apertures. This poses a problem as the gases containing hydrocarbons, sulphates and other particles provoke an intense and unpleasant smell that can reach the nearby residential neighborhoods. The intensity and the reach of the smells depend on a variety of factors, most importantly atmospheric and weather conditions in which there is little to no air movement and the smells do not diffuse into the atmosphere. While the current legislation allows the amount of smell emitted right now by the bitumen tanks, a stricter legislation is foreseen in the coming years. The objective of the following study is the elimination of the smells emitted by these gases in the most efficient way possible. Various alternatives were analyzed and finally a microbial digestion of the gases was chosen as it assures the elimination of the smells and can work with a large variety of contaminants. Before the biological treatment, the condensable particles in the gas stream are eliminated to ensure a full aerobic digestion in the biological reactor. This is accomplished with the use of the proceso 0 in which the gases pass through two carbon filters that are often and automatically sprayed with gasoil to ensure its efficiency. This process causes the condensable particles in the gas stream to condense and they are then eliminated through a liquid stream. The gases are then fed to the biological reactor through the work of a compressor. The biological treatment works in a similar way to an industrial wastewater treatment plant, through aerobic digestion and producing a stream of clean water which can be fed directly into Tarragona’s industrial water emissary after being properly analyzed, or into ASESA’s own WWTP for further treatment. Parallelly, a flux of treated gases containing less complex metabolites and inorganic minerals are released into the atmosphere. This process eliminates the majority of smells, but a secondary procedure of smell encapsulating spray is installed above the biological reactor to eliminate any residual smells. The designed process ensures the complete elimination of the smells.