Cooling from

Example 7.3 A hot stream is to be cooled from 410 to 110°C by exchange with... 

Use Equipment Only When deeded. Start morning warm-up no earHer than necessary and do not use outside air for ventilation until the building is occupied. Use minimum amounts of outdoor air according to reference 8. Supply heat at night only to maintain a temperature above 13°C. Supply Heating and Cooling from the Most Efficient Source. 

Fig. 17. Structuie of U-700 after piecipitation hardening temperature of 1168 C/4 h + 1079" C/4 h + 843 C/24 h + TGO C/IG h with air cooling from each temperature. A grain boundary with precipitated carbides is passing through the center of the electron micrograph. Matrix precipitates are y -Nij(TiAl).

A nonaHoyed carbon steel having 0.76% carbon, the eutectoid composition, consists of austenite above its lowest stable temperature, 727°C (the eutectoid temperature). On reasonably slow cooling from above 727°C, transformation of the austenite occurs above about 550°C to a series of parallel plates of a plus cementite known as peadite. The spacing of these plates depends on the temperature of transformation, from 1000 to 2000 nm at about 700°C and below 100 nm at 550°C. The corresponding BrineU hardnesses (BHN), which correspond approximately to tensile strengths, are about BHN... 

When a eutectoid steel is slowly cooled from the austenite range, the ferrite and cementite form in alternate layers of microscopic thickness. Under the microscope at low magnification, the diffraction effects from this mixture of ferrite and cementite give an appearance similar to that of a pearl, hence the material is called peadite. 

Several plants employ cooled-belt flakers. These consist of flexible steel belts, ca 1-m wide and up to 50-m long, that have short mbber skirting at the edges. Molten pitch flows from a thermostatically controlled tank over a weir to give a flat thin sheet on the belt, which is cooled from below by water sprays. At the end of the belt, the solid pitch is broken up by rotating tines. The pitch flakes are drained and transported to a covered storage silo by belt conveyor, during which time the surface moisture evaporates. 

Some materials that are prepared in the molten state are converted advantageously to flake form by cooling a thin layer continuously on the surface of a rotating drum. Another way is to spray cool from the melt, using a spray diyer with cold air. Thus, massive cooling and subsequent pulverizing are avoided. See the Index for details of these other methods. 

Quenching Rapid cooling from an elevated temperature, e.g., severe cooling of the reaction system in a short time (almost instantaneously), freezes the status of a reaction and prevents further decomposition or reaction. 

Cupric nitrate (3H2O) [10031-43-3 (3H2O) 3251-23-8 (anhydr)] M 241.6, m 114 , b 170 (dec), d 2.0. Crystd from weak aqueous HNO3 (0.5mL/g) by cooling from room temperature. The anhydrous salt can be prepared by dissolving copper metal in a 1 1 mixture of liquid NO2 and ethyl acetate and purified by sublimation [Evans et al. J Chem Soc, Faraday Trans 1 75 1023 1979], The hexahydrate dehydr to trihydrate at 26°, and the anhydrous salt sublimes between 150 and 225°, but melts at 255-256° and is deliquescent. 

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