Spray Scrubbing of Particulates with a Critical Flow Atomizer

• Published in: Chemical engineering & technology 2007-12, Vol.30 (12), p.1674-1685
• Main Authors: Bandyopadhyay, A., Biswas, M. N.
• Format: Article
• Language: English
• Subjects: Air pollution; Applied sciences; Chemical engineering; Exact sciences and technology; Hydrodynamics of contact apparatus; Scrubbers; Spray tower; Two-phase flow
• ISSN: 0930-7516; 1521-4125
• DOI: 10.1002/ceat.200700230

Wet scrubbers are gaining importance over other devices for particulate collection with the increasing stringency of pollution regulations. The scrubbing of particulates (soot and fly‐ash) in a spray tower with a two‐phase critical flow atomizer using water is reported in this article. The atomizer is capable of generating droplets with a high degree of spray uniformity. Preliminary studies reveal that the atomizer deployed in the present investigation is energetically more favorable than existing atomizers. With this atomizer, the scrubbing performances of a model spray tower are determined experimentally in terms of different operating variables. Various physical interactions with the exception of electrostatic effects are found to significantly influence the removal efficiency. The removal efficiency is found to increase with the inlet particle loading, gas flow rate and liquid to gas flow rate ratio. Experiments reveal that the present system collects finer (soot) particles (with a Sauter Mean Diameter (SMD) of 1.43 μm) more efficiently than the relatively coarse (fly‐ash) particles (SMD of 6.38 μm) under similar experimental conditions. Further investigation reveals that almost 100 % removal efficiency (zero penetration) of both soot and fly‐ash particles can be attained at a much lower QL/QG ratio of 3 m3/1000 actual cubic meters (ACM) than for the existing systems. A unique correlation is developed for predicting the performance of the spray tower in terms of various pertinent variables of the system. The predicted values agree very well with the experimental values (± 10 % deviation). A comparison of the performance of the present system with the existing systems indicates that the spray tower developed is techno‐enviro‐economically more favorable than existing systems. The scrubbing of particulates (soot and fly‐ash) in a spray tower with a two‐phase critical flow atomizer using water is reported. Preliminary studies reveal that the developed spray tower atomizer has achieved better scrubbing performance than the existing spray scrubbing devices for particulate removal from energy, hydrodynamic and efficiency viewpoints.