Steam superheated water

The effect of superheated steam may be illustrated by reference to baizaldehyde, which boils at 178° at 760 mm. It distils with steam at 97-9° (Pj = 703-5 mm. and pg = 56-5 mm.) and the distillate contains 32-1 per cent, of benzaldehyde by weight. If one employs steam superheated to 133°, the vapour pressure of benzaldehyde (extrapolated from the boUing point - pressure curve) is 220 mm. hence pj = 540 (water), Pg = 220 (benzaldehyde), and... 

Saturated or superheated steam flows on the shell side and FW on the tube side. Closed FW heaters are so called because the steam and water do not come into contact with each other. Most are of a horizontal design although vertical FW heaters are manufactured. 

Meluch et al.10 reported that high-pressure steam hydrolyzes flexible polyurethane foams rapidly at temperatures of 232-316°C. The diamines are distilled and extracted from the steam and the polyols are isolated from the hydrolysis residue. Good results were obtained by using reclaimed polyol in flexible-foam recipes at file 5% level. Mahoney et al.53 reported the reaction of polyurethane foams with superheated water at 200°C for 15 min to form toluene diamines and polypropylene oxide. Gerlock et al.54 studied the mechanism and kinetics of the reaction... 

As indicated in Sec. IIB, ordinary nucleate boiling is a two-step process. First, nuclei must appear. Second, the nuclei must grow into bubbles large enough to move away from the nucleation sites. The rate of heat absorption by the liquid may be controlled by either one or both of these two processes. The growth of a nucleus (tiny bubble) into ordinary bubbles has received attention recently. The theoretical attack of Forster and Zuber was discussed in Sec. IIB2. Inasmuch as the theory of Zwick and Plesset (P3, P4, Zl, Z2) represents another attempt to obtain exact expressions for bubble growth, and since the theory fits well with the few data for steam bubbles in superheated water, their theoretical method is summarized below. 

Replacing sterilizers that operate by one set of principles with sterilizers that operate by another principle (e.g., substituting a gravity displacement steam process with a process using superheated water spray). 

Fig. 5. In a double-flash plant for producing electricity from hydrothermal water, superheated water is delivered from the well, A, to an initial flashing unit, B, where the pressure is reduced to release steam which drives a turbine, D. The liquid fraction is then delivered to a second flashing unit, C, where further pressure reduction produces more steam which is introduced to the turbine at an intermediate stage. The waste fluid from the second flashing stage, E, may contain very high concentrations of dissolved or suspended solids, presenting significant disposal problems. The spent steam can be recondensed and...

Figure 8.1 BKZ-320-140GM impinging stream steam boiler. 1 burner 2 combustion space 3 secondary combustion space 4 steam superheating 5 water economizer.

The cooking conditions within an expanding/extmder soften and gelatinize the oilseed s protein, converting the protein into a glue-like condition that binds all the particles together. The gelatinized protein is elastic and allows the collets to inflate with internal pores as some of the superheated water flashes into steam when the collets exit into atmospheric pressure (104). 

Moist-heat sterilization is achieved when a suitable combination of temperature and humidity can be introduced (or indirectly generated) at the level of the micro-organisms to be inactivated. The classic way to achieve this is by means of pressurized saturated steam at the temperature of 121°C (250°F). However, other sterilizing media (e.g., superheated water or a steam-air mixture) are also frequently used to obviate certain problems that pure steam may pose. Sometimes the load is rotated inside the chamber of the sterilizer to achieve particular results. 

Current pharmaceutical production practice uses substantially three moist-heat sterilization processes 1) pressurized saturated steam 2) superheated water and 3) steam-air mixture. Process 1 is the traditional multipurpose process, which obviously uses pure pressurized saturated steam as sterilizing medium. Processes 2 and 3 are so-called counterpressure processes they were introduced in pharmaceutical production practice approximately 20 years ago and, respectively, use a spray superheated water and a homogeneous... 

Accordingly, a dual control principle is provided that acts independently on both parameters. Two methods currently in use are superheated water spray and steam-air mixture. 

With steam-air autoclaves, blushing of PVC bags is generally less intense than with superheated water spray autoclaves and essentially affects only the areas where the bags rest on the supporting racks. Among... 

Fig. 8 Critical comparison of superheated water spray (SWS) and steam-air mixture (SAM) autoclaves. (Adapted from Ref. l)...

The flue gas is cooled to about 600°F. by passage through a waste-heat steam boiler, and further cooled to 400°F. or lower by injecting a spray of superheated water, before introduction into the Cottrell (234). A 20-25 vol. % concentration of water vapor is maintained in the gas in order to minimize arcing. Injection of a small amount of ammonia, about 0.005% by weight of the flue gas, has also been found beneficial. 

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