Designing a new system for removing condensable gaseous pollutants by means of separation techniques

Many industrial processes produce gaseous contaminants that must be removed, at least partially, before exhausting the fumes in the atmosphere and fulfil the limits set by environmental protection agencies. Rubber vulcanization fumes and wood pyrolysis are typical examples of those processes. In other processes, such as coffee roasting, huge quantities of these contaminants are produced and, not being able to be captured, they are dispersed in the air thus cancelling their commercial value. Current technologies for removing gaseous contaminants require intensive maintenance and/or high operating costs. Thermal oxidation in case of high concentrations of pollutants, activated carbon adsorption with period regeneration and electrostatic precipitation of the condensed particles are among the most common technologies used for this purpose. In this work we present part of the design of a new patented system which removes the gaseous pollutants by forcing them to condense suddenly in small droplets. The liquid aerosols obtained in this way are then separated by means of a specially designed cyclone. Every single application needs a specialized design, both for the condensing section and for the inertial separator. The calculations presented here focus mainly in the condensing section. The simulations were based on Computational Fluid Dynamics (CFD), using specific models and pieces of code to simulate the nucleation, condensation, growth and coagulation of the liquid particles to be separated. In addition to the simulation tool, two models were also developed, the first zero-dimensional and the second one-dimensional, through which the partial differential equations describing the problem were solved numerically, in order to understand what happens into the condensing section. The results obtained are encouraging so that the following step would consist into building a prototype to demonstrate the potential of the invention.