tailieunhanh - Modeling of Combustion Systems A Practical Approach 10

Tham khảo tài liệu 'modeling of combustion systems a practical approach 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 2 Introduction to Combustion Chapter Overview This chapter overviews some practical and theoretical aspects of combustion. We first discuss burners generically including fuel and air metering flame stabilization and shaping and some fundamental techniques for control of emissions such as NOx. So prepared we move on to consider archetypical burners those representative of the traditional classes of burners one might find in a refinery or petrochemicals plant or that provide heat for steam. We build upon this foundation by next considering archetypical process units such as boilers process heaters of various types and reactors such as hydrogen reformers and cracking units. In order to lay the groundwork for more detailed combustion modeling the chapter considers important combustion-related responses such as NOx emissions flame length noise etc. and the factors that influence them. Historically practitioners have defined a traditional test protocol for quantifying these effects which we present. We also consider some aspects of thermoacoustic instability this has become a more important topic with the advent of ultralow NOx burners employing very fuel lean flames. In the latter third of the chapter we develop stoichiometric and mass balance relations in considerable mathematical detail. We also consider energy-related quantities such as heat and work adiabatic flame temperature and heat capacity. As well we relate the practical consequences of a mechanical energy balance as applied to combustion equipment. Such things include draft pressure incompressible airflow compressible fuel flow and practical representations thereof capacity curves for air and fuel. 101 2006 by Taylor Francis Group LLC 102 Modeling of Combustion Systems A Practical Approach General Overview Combustion is the self-sustaining reaction between a fuel and oxidizer characterized by a flame and the liberation of heat. Usually but not always the flame is visible. A flame is the reaction zone .