DriSteem Vaporstream Specifikace stáhnout pdf (Strana 73)

P a g e 6 8 • D R I - S T E E M D e s i g n G u i d e

D R I - S T E E M D e s i g n G u i d e • P a g e 6 9

eliminates heat gain during the “off” humidification periods only

(see Figures 68-1 and 69-1). The jacketing steam valve should be

a two-position type, with a minimum Cv of 5, and set to the full-

open position prior to opening the modulating valve.

In Figure 68-1, all of the steam (for jacketing and humidification)

must pass through the jacket steam valve, and it must do so with

very little or no pressure drop across the valve, or maximum

capacity will be reduced. More importantly, with just one supply

source for jacket and humidification steam, the temperature of the

jacket steam may drop below the temperature required to eliminate

dripping. Therefore, the valve must be adequately sized. This is

not significant in a small capacity humidifier. However, in a large

capacity humidifier, the valve of the size required may be quite

expensive. Another option is to install two valves: one sized for

jacket steam and one sized for humidification steam.

Figure 69-1 shows a steam flow that has been divided into two

paths: a humidifying steam path (which passes through the

separator valve assembly) and a jacket steam path. When dividing

the steam path, install a temperature switch as shown in the

drawing to ensure that condensate is not present when the control

valve opens. Install a header trap, as shown, to collect condensation

when the jacket steam is off.

Figure 69-1:

Divided humidifying steam path

Note: Due to the pressure drop across the

valve, the steam pressure at the header

trap is minimal; therefore, you cannot

lift condensate or return condensate to a

pressurized return from this trap.

Jacketing steam on-off valve

Modulating control valve

Temperature switch

Header

trap

Drain

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DriSteem Vaporstream Specifikace Strana 73