Heat coil-wound

Steam is supplied to the heating coils of a reactor vessel at 125 psig, saturated. The coils are 0.5-in schedule 80 pipe (internal diameter = 0.546 in). The steam is supplied from a main header through similar pipe with an equivalent length of 53 ft. The heating coils consist of 20 ft of the pipe wound in a coil within the reactor. 

Fredheim, A.O. Thermal design of coil-wound LNG heat exchangers, shell-side heat transfer and pressure drop , Dr.ing. thesis, NTH, 1994... 

Electrical heating circuit for solution calorimeter. The standard resistor should be a wire-wound resistor with a low temperature coefficient and rated for 2 W. If a heating coil of higher resistance (say, 60 2 is to be used, the current can be reduced to 0.5 A and a 1-H standard resistor can be used. 

A quartz reactor tube o (O.D. 34 mm., I.D. 30 mm., over-all length 1500 mm.) is wound over a length of 650 mm. with a heating coil c, which is cemented to the tube with a thin quartz-waterglass slurry. Molybdenum boat t is placed in the heated zone. The radiation shield d retards heat loss to the outside. Switch m controls the heat input to the winding, sensing the pressure developed by the hydrogen product stream. 

Natural gas is fed to the propane chilling section where is it cooled from ambient temperatures to approximately -35°C. Then the pre-cooled feed enters the Main Cryogenic Heat Exchanger (MCHE), which is a coil wound heat exchanger (CWHE) [2]. There, the natural gas is liquefied with a mixed refrigerant (MR) which is a combination of nitrogen, methane, ethane, and propane. The composition is optimized to maximize the process efficiency. Finally, the LNG exits the MCHE and goes to the end flash unit (not shown), where it is split into a fuel gas stream and LNG product. 

The furnace heating coil is wound non-induc-tively to avoid magnetic interactions between the coil and the sample. Coils are made from various materials, such as nichrome (T < 1300 K), platinum (T > 1300 K), platinum-10% rhodium (T < 1800 K) and silicon carbide (T < 1800 K). The furnaces consisting of an infrared (IR) ray heater instead of a standard coil heater are also used. An IR furnace is routinely used up to 1800 K. Using an elliptical reflector or parabolic reflector, IR... 

The heat exchange surface of a module consists of five rows of cylindrical multiple-thread coils wound on the central tube of the module. Coils are spaced in longitudinal and lateral directions using spacing combs and supporting strips. 

Fig. 7.20 Coil-wound heat exchanger on the winding bench.

Besides Air Products Chemicals, Inc., today the Linde AG is the only manufacturer worldwide of coil-wound heat exchangers suitable for base-load LNG-plants. Figure 7.21 shows two of these items manufactured by the Linde AG for an LNG-plant in Australia that works according to the C3MR-process. 

Fig. 7.21 Coil-wound heat exchanger ready for shipment.

For large motors, the practice is to wind the stator with formed coils (Figure 9.2). The coils are pre-formed and cured before insertion into the stator slots. They are insulated with resin-rich glass and mica paper tapes. The process of impregnation is therefore termed resin-rich insulation. The completed formed wound stator is then heated to remove trapped moisture and finally impregnated in varnish class F or H as required, under vacuum and pressure. The stator is then cured in an oven as described above. The process of insulation and curing conforms to powerhouse insulation requirements. This practice facili-... 

Coil boilers are available as fully automatic package units, typically ranging in size from 15 to 300 boiler hp (500 lb/hr-10,000 lb/hr). Most designs employ forced circulation and a single, continuous spiral, helical-wound coiled tube that hangs inside the furnace. The coil is subjected to intense heat release from a gas or oil burner. 

Toluene is continuously nitrated to mononitrotoluene in a cast-iron vessel, 1 m diameter, fitted with a propeller agitator 0.3 m diameter rotating at 2.5 Hz. The temperature is maintained at 310 K by circulating 0.5 kg/s cooling water through a stainless steel coil 25 mm o.d. and 22 mm i.d. wound in the form of a helix, 0.80 m in diameter. The conditions are such that the reacting material may be considered to have the same physical properties as 75 per cent sulphuric acid. If the mean water temperatute is 290 K, what is the overall coefficient of heat transfer ... 

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