Heat processes

A. Muhlbaur, "Electrical Energy for Heating Processes for the Euture," Electrowarme Int. 49(B3), B58 (1991), a review of various electric heating and melting industrial appHcations. 

Phase Materials. Phase holograms can be recorded in a large variety of materials, the most popular of which are dichromated gelatin, photopolymers, thermoplastic materials, and photorefractive crystals. Dichromated gelatin and some photopolymers require wet processing, and thermoplastic materials require heat processing. Photorefractive crystals are unique in that they are considered to be real-time materials and require no after-exposure processing. 

Milk has been a source for food for humans since the beginning of recorded history. Although the use of fresh milk has increased with economic development, the majority of consumption occurs after milk has been heated, processed, or made into butter. The milk industry became a commercial enterprise when methods for preservation of fluid milk were introduced. The successful evolution of the dairy industry from small to large units of production, ie, the farm to the dairy plant, depended on sanitation of animals, products, and equipment cooling faciUties health standards for animals and workers transportation systems constmction materials for process machinery and product containers pasteurization and sterilization methods containers for distribution and refrigeration for products in stores and homes. 

Technology Country Heating process Feed Flow ... 

Above-Ground Retorting. AGR processes can be grouped into DH or IH processes. Numerous design configurations as well as a variety of heat-transport mediums have been used in the indirect heated processes (Table 7). 

Raw lac is first treated to remove water-soluble carbohydrates and the dye that gives lac its red color. Also removed are woody materials, insect bodies, and trash. It is further refined by either hot filtration or a solvent process. In the heat process, the dried, refined lac is filtered molten through cloth or wine screens to produce the standard grades of orange shellac. In the solvent process, lac is dissolved and refluxed in alcohol solvents, filtered to remove dirt and impurities, and concentrated by evaporation. The lac can be further decolori2ed in this process to produce very pale grades. Bleached shellac is prepared by treatment with dilute sodium hypochlorite and coalesced into slabs. 

Heat-processed photographic systems have been described that utilize silver behenate, silver laurate, and silver stearate. These silver salts are coated on paper in the presence of organic reducing agents (78,79). 

The concept of heat processing of foods in hermetically sealed containers was introduced in 1810 (23). The role of microorganisms was unknown at the time, and only the so-called agents of putrefaction were eliminated. 

In these processes, the starch slurry is prepared in the same manner as in the low temperature process. In a dual-enzyme/dual-heating process, the steps ate the same as the low temperature process until the completion of the second-stage reaction. Then, a 2—5-min heat treatment foUowed by a second enzyme addition and another reaction step is employed. In a dual-enzyme/single-heating process, the starch slurry is immediately heated to 145—150°C for one minute or less. Although the enzyme is rapidly inactivated, sufficient hydrolysis takes place to provide a partially thinned hydrolyzate that can be pumped to a second stage where additional enzyme is added and the reaction continued at 95—100°C for 20—30 minutes. The temperature is then lowered for the remainder of the reaction. 

Application Techniques, Structural Variations, and Fastness Properties. When appHed to polyester fiber, many of the disperse dyes originally developed for ceUulose acetate were found to be deficient in Hghtfastness, build-up properties, and especially fastness to the high temperatures employed in the newer dyeing and finishing, printing, and Thermosol (dry heat) processes. 

Filter P per Processing. In the fabrication of fuel oil and air filters for vehicles such as motorcycles and diesel locomotives, heat processing of the filter paper is required to cure the resin (usually phenoHc) with which the paper (qv) is impregnated (see Phenolic resins). The cure-oven exhaust, which contains water vapor, alcohols, and dimers and trimers of phenol, produces a typical blue haze aerosol having a pungent odor. The concentration of organic substances in the exhaust is usually rather low. 

REIST Aerosol Science and Technology, Second Edition RHINE, TUCKER Modeling of Gas-Fired Furnaces and Boilers and Other Industrial Heating Processes ROSSITER Waste Minimization Through Process Design SAMDANI Safety and Risk Management Tools and Techniques in the CPI... 

Contactive (Direct) Heat Transfer Contactive heat-transfer equipment is so constructed that the particulate burden in solid phase is directly exposed to and permeated by the heating or cooling medium (Sec. 20). The carrier may either heat or cool the solids. A large amount of the industrial heat processing of sohds is effected by this mechanism. Physically, these can be classified into packed beds and various degrees of agitated beds from dilute to dense fluidized beds. 

Shelf Devices Equipment having heated and/or cooled shelves is available but is httle used for divided-sohds heat processing. Most extensive use of stationaiy shelves is freezing of packaged solids for food industries and for freeze drying by sublimation (see Sec. 22). 

Substantial energy can be recovered using low-grade waste heat, process gas, or waste gas pressure letdown. 

Spirai Compact, concentric plates no bypassing, high turbulence. Cross-flow, condensing, heating. Process corrosion, suspended materials. 0.8-1.5... 

The seedlac may then be converted to shellac by either a heat process or by solvent processes. In the heat process the resin is heated to a melt which is then forced through a filter cloth which retains woody and insoluble matter. In the solvent process the lac is dissolved in a solvent, usually ethyl alcohol. The solution is filtered through a fine cloth and the solvent recovered by distillation. 

Receptor hoods, also called canopy hoods, are designed to capture contaminants given off by heated processes. They take advantage of the thermal updraft caused by such processes by placing the hood in the path of the updraft, they receive the exhaust and capture the contaminants. 

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