Steam supply generation

Steam generated from an external source positioned close to the unit is injected into the airstream. It is essential that the steam supply is uncontaminated and odorless. In order to stop scale buildup, it is essential that some means of water treatment be provided. 

Larger clean-steam generator designs typically employ a pressure vessel (shell) containing a U-shaped tube bundle. The heat source is primary steam supplied to the shell side (which may be amine treated), and secondary clean steam is generated within the tubes. 

A schematic drawing of the nuclear steam supply system is provided in Figure 2.7, and a drawing of a nuclear boiler is shown in Figure 2.8, with the various steam generation zones indicated. 

A plant is proposing to install a combined heat and power system to supply electrical power and process steam. Power is currently taken from a utility company and steam is generated using on-site boilers. 

Utility functions such as the supply of steam and cooling water generally are set up to service several processes. Boiler feed water is prepared and steam is generated in a single boiler house. Noncontact steam used for surface heating is circulated through a closed loop, whereby various quantities are made available for the specific requirements of the different processes. The condensate is nearly always recycled to the boiler house, where a certain portion is discharged as blowdown. 

Water baths are the more common of the two, and the steam is generated by heating water with an electric element - just like a kettle. The element may have a thermostatic control, which can control the temperature of the water to some extent. Most water baths have a constant level device on the side of the bath, which supplies water to the bath to a fixed level above the heating element and prevents the water bath from boiling dry. Water baths are single hole or multiple hole types, and the holes are covered by concentric metal or plastic rings, which allows you to vary the size of the hole. 

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