Industrial Heating Applications Research Articles

Consequences of recent gas turbine developments for industrial CHP applications

Developments in gas turbine (GT) technology have been considerable during the last few years. In this paper, consequences regarding the technical performance for industrial combined heat and power applications are discussed and the most important design parameters are identified. Some GT types, which represent different stages of the developmental trend, are analysed in the simple and the combined cycle. Both the industrial and the aero-derivative GT classes are included. Conclusions are: (i) Generally, the developments have broadened the span of achievable power-to-heat ratios (α-values). Values between 0 and 1.5 are obtainable for different GT-based schemes with acceptable total efficiencies. (ii) The total efficiencies achievable depend strongly, and differently for different GT types, on the nature of the heat demands in the industrial process. (iii) When opportunities do not exist to cool the exhaust gases in an economizer, i.e. when the stack temperature is directly given by process heat demands, the total efficiency is independent of the GT class. For both classes, however, the development has led to higher total efficiencies when the process temperature demands are high. (iv) When opportunities exist to cool the exhaust gases in an economizer (which is often the case for the simple cycle and always for the combined cycle), the industrial GT developments have given improved ability to reach a high total efficiency. The new aero-derivative types, on the contrary, are worse than the conventional ones in this respect. This can also lead to worse performance in combined cycles for the new aero-derivative types. (v) When supplementary firing is applied, however, the total efficiency is high and similar for all various units and conditions. The ‘new aero-derivative’ units have, in that case, superior α-values—especially in the combined cycle.

Fiberoptic Thermometry and its Applications

This paper reviews briefly the reasons for interest in fiberoptic thermometry and the various types of fiberoptic temperature sensors which have been developed to the point of commercialization. It then focuses on a particular technology in which the rate of decay of fluorescence from a phosphor sensor is utilized to determine temperature. This technology provides essentially calibration-free operation and easy interchangeability of a wide variety of applications-specific probe types. After describing the available systems, the paper addressed briefly a number of key applications including usage in high voltage transformers, industrial microwave heating applications, electromagnetically-induced hyperthermia, electronics fabrication and testing and magnetic resonance.

The value of improvements in the absorbing and glazing surfaces of solar devices

Simulation techniques are used to examine the value of various technical improvements in solar collection-storage devices in residential, industrial and agricultural passive space heating applications. The improvements include decreased emittances and increased absorptances in absorbing surfaces, and decreased reflectances and emittances in glazings. The improvements are evaluated in the context of a single family house and of an agricultural and an industrial application having large ventilation requirements. The results of this study show that decreases in glazing reflectance are of the most value, followed (in order of likely decreasing importance) by increased absorber absorptance, decreased absorber emittance, and decreased glazing emittance. These qualitative results should not be used to determine or guide research priorities directly; rather, individual research programs should be evaluated using the quantitative results of this study in conjunction with other applicable information.

Microwaves for cooking and heating

A microwave oven is a common item in the modern kitchen. This article explores the history, development and problems involved with microwave ovens and also explores other domestic and industrial heating applications

RCA 915-MHz Power Oscillator for Microwave Cooking and Industrial Heating Applications*

AbstractThis paper describes a unique triode tube, power oscillators, and power-supply systems which can provide 915-MHz power from 300 to more than 2000 watts for microwave cooking and industrial heating applications. The paper also discusses the advantages of operating at 915 MHz and the advantages of triodes over magnetrons; in particular, a triode has a greater tolerance of unusual load conditions. The excellent low-voltage characteristics of the recently developed RCA power oscillator permit high performance to be obtained with simple low-cost transformerless voltage-doubling power supplies operating from standard power-line voltages. Techniques are described for automatically matching the load to the oscillator to achieve near-optimum transfer of energy under a wide range of loads. Several applications of the system are presented.

Transient voltages in rectifier transformers

This paper discusses transient-voltage phenomena which occur in rectifier circuits involving mercury-vapor hot-cathode tubes commonly used as power sources in many electronic equipments such as broadcast transmitters, high-frequency industrial-heating applications and the like. In particular, reference is made to equipments with power outputs in the range 10?200 kw with direct voltages of 3 to 15 kv.

The Design of High Power Vacuum Tubes for Industrial Heating Applications

Analysis of tube failures from industrial application has pointed up three principal sources of failure: (1) copper-glass seals are not strong enough to withstand handling by industrial maintenance people; (2) filament structures of the spring-tensioned type are not too reliable; (3) thin-walled copper anodes will not stand occasional overloads. Tubes have been designed which greatly increase tube life by eliminating failures of the above types. The use of thick kovar metal in glass seals will withstand about ten times the torsion of the conventional copper seals commonly used in transmitter tubes. A self-supporting filament structure not only eliminates the failures caused by filaments sticking in guides and annealing of the spring material, but maintains uniform tube characteristics throughout life. Data on a type ML-5658 20-kw tube shows less than 2 per cent change in static data after 10,000 hours of life. The use of copper anodes from four to eight times thicker than customary permits nearly 100 per cent increase in plate dissipation ratings without additional water flow. For use at normal plate dissipation, the anode temperature runs lower and scaling of the anode, with resultant anode puncture, is eliminated. Failure of tubes due to excessive cathode temperature cannot be reduced since evaporation of the cathode material is a physical reality which cannot be compromised. Instead of running a tube above ratings, a larger tube with greater cathode area must be used.