Separation of Aerosols by Localized Vapor Condensation

PAOLO TRONVILLE, María José Rubio, Jesús Marval, Juan Vallejo, Politecnico di Torino

     Abstract Number: 197
     Working Group: Control and Mitigation Technology

Abstract
Many industrial processes generate vapors that must be removed from the exhaust fumes to obey maximum allowable emissions limits set by environmental protection agencies. Other processes, e.g., coffee roasting, release significant amounts of vapors that may have a commercial value into the atmosphere. These substances tend to condense in the exhaust systems, causing an economic loss due to the maintenance of the ducts and production stops. Hence, it is desirable to capture those vapors effectively, turning them into a resource whenever possible.

Examples of technologies suitable for removing vapors from the air are thermal oxidation, activated carbon adsorption, and wet scrubbers. However, those technologies require frequent maintenance and high operational costs.

We present experimental results measured on a prototype built to demonstrate the operation of new patented technology to remove vapors from the air. The idea is to force the vapor condensation into tiny droplets and separate them using a high-efficiency cyclone.

The fumes are cooled down and go through the device designed to separate the organic compound. After the inertial separation phase, part of the fumes is refrigerated and used to produce the condensation of the organic contaminant upstream of the inertial separator. At the same time, the remaining amount can be reintroduced into the oven. From the inertial separator, it is possible to collect the condensed contaminants. To obtain the desired result is crucial to identify the proper cooling temperature and airflow, optimizing the energy use to maximize the efficiency of this new technology.

The measured prototype’s collection efficiency was around 50%. The mass of the condensed contaminant depends on the cooling power available. We will refine the prototype further because the mass balance cannot be closed with available data. In future steps, the cooling section of the prototype can improve by introducing new heat exchange devices to promote the nucleation of the contaminants contained in the gaseous stream. Some solutions might include adopting a conduction heat exchange mechanism.

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