Applications of Pulse Combustion in Industry

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APPLICATIONS OF PULSE COMBUSTION IN INDUSTRY Ben T. Zinn School of Aerospace Engineering Georgia Institute of Technology Atlanta, Georgia, USA ABSTRACT This paper discusses past and potential industrial applications of pulse combustion. The advantages in utilizing pulse combustors in i ndustri a 1 processes are related to the unique characteristics of these combustors and the presence of pulsations in their exhaust flows. Spec i fi c advantages of pulse combustors include: ability to burn various fuels; high combustion intensities; low NO format ion; low excess air requi rements an~ self aspiration which eliminates the need for compressors or fans to pump the air and combustion products through the system. Additionally, the presence of pulsations in the exhaust flwo enhances the rates of mass, momentum and heat transfer in the process under consideration; improvements which resu 1 tin increased output and reduced operati ona 1 costs. To date, pu 1 se combustors have been ut il i zed in such app 1 i ca t ions as drying, steam raising, heating and so on.In these app 1 i cat ions it has been demonstrated that the use of pulse combustors has resulted in capi ta 1 investment and ope rat i ona 1 cost savings. Finally, potential applications of pu 1 se combust ion in chemi ca 1 process i ng, catalytic combustion, gasification and so on are discussed in the paper. THIS PAPER DISCUSSES THE STATE OF THE ART and potential applications of pulse combustion in industrial processing. While interest in pulse combustion has been increasing in recent years, there are indications that this technology remains virtually unknown to a large number of energy intensive industries. Perhaps the best known app 1 i cat i on of pulse 55 combust i on technology to date is the Lennox pulse furnace which has been developed a few years ago and has been successfully marketed in the US. Pulse combustors differ from their steady state counterparts by the fact that conditions within their combustion zones and the properties of thei r combustion products vary periodically with time. Significantly, as will be discussed later on in this paper, the presence of these pu 1 sat ions ins i de the combustor and in the generated hot combustion products offers a number of advantages which are highly attractive from a combustor design and process applications points of view. In general, pulse combustion operation occurs when the heat released by the combustion process spontaneously excites the fundamenta 1 acousti c mode of the combustor. The exc i ted acoust i c pressure and ve 1 oc i ty oscillations interact with the combustion process resulting in periodic reaction and heat release rates. If the periodic heat release rate is in phase with the local acoustic pressure oscillations driving of the acoustic mode by the combustion process will occur and the pu 1 sati ng combustion process could maintain itself indefinitely. This condition is generally referred to as Rayleigh's criterion. Research conducted to date (e. g., see Refs. 1-7) has shown that the presence of pu 1 sati ons ina flow increases the rates of mass, momentum and heat transfer processes. Since the rates of most combustion processes depend upon the rates of the vari ous transport processes, one would expect that the intensity and efficiency of the combustion process will increase as the rates of the vari ous transport processes increase due to the presence of pulsations within the combustor; an expectatio(8_rr~ch has been confirmed in practice . Also, the enhanced mlxlng rate associated with the presence of flow pulsations often reduces the