Direct steam injection

The Vepex process developed in Hungary (Table 9) involves disintegration of plant materials followed by double screw pressing to maximize juice production. Green chloroplastic protein is removed by direct steam-injection heat treatment at 82°C with the addition of flocculents and centrifugation. The white protein fraction is separated from the chlorophyU-free process juice by direct steam injection at 80°C, followed by centrifugation and drying (94). 

Dutt, S. (1996). Safe Design of Direct Steam Injection Heaters. 5th World Congress of Chemical Engineering, July 14-18, 1996, San Diego, CA, Paper 52c. New York American Institute of Chemical Engineers. 

This system requires direct steam injection into the still with the liquid, all the steam leaves overhead with the boiled-up vapors (no internal condensation) in a steady-state operation, and system at its dew point. Steam is assumed immiscible with the organics. Steam distillation is usually applied in systems of high boiling organics, or heat sensitive materials which require separation at vacuum conditions. 

Pick, A. E., Consider Direct Steam Injection for Heating Liquids, Chem. Eng, p. 87, June 28, (1982). 

Empty vessel, sterilisation of vessel and piping using direct steam injection... 

The use of direct steam injection into air is a common method of increasing humidity levels for both commercial and industrial applications. The process kills most types of bacteria and similar organisms that may contribute to fouling, health, or other indoor air quality (IAQ) problems. Where amines are present in the steam, however, even small concentrations can be detected by their odor and may be objectionable, even though they may be well under guidelines for concentrations in air. 

Figure 11.17 Substitute some (or all) of the reboiling with direct steam injection and introduce intermediate condensation.

Washing the tetryl. The filtered product is despatched in aluminium barrels from the nitration department to a special room where it is poured into a washing tank (Fig. 9). The tank of 1350 1. capacity, fitted with a stirrer, may be of wood lined with stainless steel. It is fed with water through pipe (/), and is heated by direct steam injection through pipe (2). 

The suspension of cut nitrocellulose fibres in water is transferred with the help of a pump into a boiler (poacher). This is a vertical (Fig. 160) or horizontal (Fig. 161) cylindrical vessel of 10-20 m3 capacity, constructed of sheet-metal, equipped with a stirrer and heated by direct steam injection. 

Figure 9.4 Hot water circulation with direct steam injection.

The usual equipment for pressure digestion consists of horizontal roll autoclaves or vertical autoclaves equipped with a stirrer. For NaOH leaching. Inconel-lined vessels are necessary, while mild steel can be used in case of sodium carbonate. Heating is performed by direct steam injection. 

The primary source of heat is hot water. The hot water is heated by direct steam injection in the hot water heater. Three PID controllers are used to control product temperature. The first control loop regulates the... 

Figure 4.17 Stripping tower with direct steam injection (dotted line indicates control volume), Example 4.5.

---