Induction heating systems

Noise protection is needed to protect against RFI/EMI problems caused by mobile and stationary radio, television, and handheld walkie-talkies radio-controlled overhead cranes radar induction heating systems static discharge high-speed power-switching elements high-AC current conductors large solenoids and relays transformers AC and DC motors welders and even... 

Shinn (1982) developed a mechanically agitated slurry reactor with induction heaters for coal liquefaction. While the induction heaters required large power input, they allowed the slurry to heat up to 400-450°C in few minutes, thus cutting down the heat-up period. In the use of such reactors, the effects of induction heating on the metal degradation and failure need to be carefully considered. Except for the induction heating system, the rest of the reactor was a conventional slurry reactor. The concept of induction heating is more practical for smaller-size reactors. 

Induction heating systems, skin effect heating, dielectric heating or systems with a current passing through a liquid, an enclosure or pipework are not within the scope of increased safety. However, resistance heating devices... 

The p-type manganese silicide sintered element used ia this investigation were formed in the shape of sintered (7mm in diameter) cylindrical pellets by means of the processing as shown in Pig.l. The raw materials of Mn(4ISI) and Si(4N) were mixed in the ratio of (Mn Si = 1 1.73) and directly melted by Radio-Frequency induction heating system in a graphite crucible under vacuum. The small amoimt of Ge was added in the raw material as a dopant. In order to... 

A 75-ml Parr high-pressure reaetor (Parr Instrument, MoUne, IL, USA) was used for hydrothermal treatment of the feedstoek. The reaetor consists of a reaction cylinder and a pressure gauge/valve assembly. An induction heating system, whieh allows the reduction of heat-up times by about two orders of magnitude, was customized by L.C. Miller, Monterey Park, CA, USA. For a typical run, 5 g of feedstock and 45 ml of distilled water were placed... 

Power Supplies and Controls. Induction heating furnace loads rarely can be connected directiy to the user s electric power distribution system. If the load is to operate at the supply frequency, a transformer is used to provide the proper load voltage as weU as isolation from the supply system. Adjustment of the load voltage can be achieved by means of a tapped transformer or by use of a solid-state switch. The low power factor of an induction load can be corrected by installing a capacitor bank in the primary or secondary circuit. 

The alternative of lower cost r-f systems, ie, induction and r-f heating systems at 40 MH2 and below, should be considered (96) (see also Furnaces, electric). More extensive discussions of the economic aspects of microwave systems and payback calculations are available (97,98). 

Thin-film epitaxy by OMCVD is generally more flexible, faster, lower in cost, and more suited for industrial production than MBE. An OMCVD system usually consists of two principal components, a gas manifold for blending the gas composition, and a graphite substrate holder which is usually inductively heated. A schematic diagram of an OMCVD system is shown in Figure 5. 

Weld joints may be coated in the field with FBE powder, utilising a portable blast cleaning/induction heating and powder application system. Alternatively joints may be provided with self-adhesive laminate tapes or heat-shrink crosslinked polyethylene sleeves. 

PVD reactors may use a solid, liquid, or vapor raw material in a variety of source configurations. The energy required to evaporate liquid or solid sources can be supplied in various ways. Resistive heating is common, induction heating of the source bottle is sometimes used, and electron beams are also employed. Molecular-beam-epitaxy (MBE) systems are PVD-type reactors that operate at ultrahigh vacuum. Very low growth rates are used ( 1 xm/h), and considerable attention is devoted to in situ material characterization to obtain high-purity epitaxial layers (2). 

Direct Sample Insertion. In direct sample insertion (DSI) [82], the sample is placed on a rod, metal loop, or cup on a rod. After desolvation (by inductive heating of the rod or use of a heat gun), the sample is inserted into the plasma. The advantages of the DSI system include nearly 100% sample transport efficiency into the ICP and use of a single power source. The most exciting capability of DSI is preconcentration using aerosol deposition that can provide two orders of magnitude of improvement in ICP-MS detection limits [83]. Detection limits as low as 0.06 parts per trillion were obtained. 

Cold wall reactors are the other major category of CVD reactors. In such systems, the substrates are heated but the walls are cooled. Figure 9 shows an example of a cold wall rotating disk CVD reactor.This system has water-cooled quartz walls, with a rotating holder for (silicon or compound semiconductor) wafers that is resistively heated from below. Other commercial cold-wall reactors include lamp heated single-wafer reactors that are widely used in microelectronics fabrication, and inductively heated horizontal flow reactors. Cold-wall reactors are often run at relatively high pressures, several hundred torr to atmospheric total... 

Microwave radiation is emitted by dryers, ovens, and heaters normally used in the home. The high-power radars used for military purposes, communication equipment, alarm systems, and signal generators are other sources of microwave radiation. The low-power microwave radiation can cause heating and skin redness whereas high-power microwave radiation can cause inductive heating of metals and induced currents that can produce electric spark. Containers with flammable materials may catch fire if they are placed in the microwave fields. Rings, watches, metal bands, keys, and similar objects worn or carried by a person in such a field can be heated vmtil they burn the bearers. 

There are several construction principles for pyrolyzers, such as with resistively heated filaments, inductively heated, furnace type, and radiatively heated. Detailed descriptions for instrument construction can be found in literature [1] or obtained from instrument manufacturers. The pyrolysis unit usually consists of a controller and the pyrolyzer itself. The controller provides the appropriate energy needed for heating. A simplified scheme of a pyrolyzer based on the design of a flash heated filament system (made by CDS Inc.) is shown in Figure 3.1.1. 

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