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Chapter 6
            Separation of Particles from a Gas












            As the counterpart of Chap. 5, this chapter covers the basics behind various particulate
            emission control devices. It starts with a general introduction to particle separation
            efficiency followed by systematic introduction to the principles for gravity settling
            chambers, centrifugal separators (cyclones), electrostatic precipitators, and filters.



            6.1 General Consideration


            Particle separation is a critical step in many energy and environmental engineering
            applications. In addition to the reduction of particulate emission before a flue gas is
            discharged to atmosphere, particle separation is an important step for alternative
            fuel development. For example, in order to clean gaseous fuel from gasification,
            heavy gas molecules have to be removed from the stream using membranes.
            However, this cannot be achieved without the removal of particulate matter from
            the gas stream, otherwise the membrane will lose its function by clogging.
              In general, a particle can be separated from its carrier gas by gravitational
            settling, cyclonic separation, filtration, wet scrubbing, thermal force separation, and
            electrical separators like electrostatic precipitators. The thermal force separators
            work in principle, but it is not effective in handling large volume of gas flow or for
            large particles [15], therefore, it will not be introduced in this book.
              The performance of a particle separation device can be quantified by the fol-
            lowing three main parameters: pressure drop, capability, and most importantly,
            efficiency.



            6.1.1 Particle Separation Efficiency


            The efficiency of a particle separator can be described by grade efficiency curve,
            which gives the separation efficiency as function of particle size. It can also be
            quantified by total efficiency.

            © Springer Science+Business Media Singapore 2014                151
            Z. Tan, Air Pollution and Greenhouse Gases, Green Energy and Technology,
            DOI 10.1007/978-981-287-212-8_6
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