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Đo nhiệt độ P19

Temperature Measurement in Industrial Appliances The majority of industrial appliances, and especially industrial heating appliances are equipped not only with temperature measurement and recording installations, but also with temperature control systems. The control systems are necessary for optimal, or at least correct, operation of technological processes such as heat treatment of metals, ceramic firing, sintering, melting, drying etc . For these reasons it has been decided to treat also the problems of temperature measurement for control purposes in this chapter . Such an approach is also justified by the common practice ofusing one temperature sensor, either as a single or double. | Temperature Measurement Second Edition L. Michalski K. Eckersdorf J. Kucharski J. McGhee Copyright 2001 John Wiley Sons Ltd ISBNs 0-471-86779-9 Hardback 0-470-84613-5 Electronic 20 Temperature Measurement in Industrial Appliances 20.1 Introduction The majority of industrial appliances and especially industrial heating appliances are equipped not only with temperature measurement and recording installations but also with temperature control systems. The control systems are necessary for optimal or at least correct operation of technological processes such as heat treatment of metals ceramic firing sintering melting drying etc. For these reasons it has been decided to treat also the problems of temperature measurement for control purposes in this chapter. Such an approach is also justified by the common practice of using one temperature sensor either as a single or double assembly for temperature measurement recording and control as previously discussed in Chapter 12. Although a really detailed analysis of temperature control problems is not possible it is important to emphasise the significant influence which the type location and dynamic behaviour of a temperature sensor has upon the results of temperature control Michalski and Eckersdorf 1987 . These aspects will be considered in detail in this chapter. Temperature measurement and control should be jointly analysed to give the highest accuracy and to grant the high infallibility and reliability of the heating appliances especially those for the heat treatment of very precious charges such as occur for example in semiconductor production. 20.2 Chamber Furnaces 20.2.1 General information A leading example of this joint treatment occurs in the temperature measurement and control of electric or gas chamber furnaces. A simplified block diagram of temperature measurement and control system of an electric chamber furnace is shown in Figure 20.1. A chamber furnace of 5 to 100 kW heating power and working temperature up to