Nortec DRAABE Pure Water System - Manual (Page 23)

Created: 21.09.2006
Changed: 29.02.2008
Printed: 02.03.2009
page 23 of 59
For a humidification rate of 57 kg/h (126 lbs/h) a 120 litre system is required, that is, the
PerPur 120. Here it does not matter how much of this total is to be used in which way. It
could all be used for humidification or some of it could be used as process water. That does
not affect the amount which passes through the water softener and wears its resins out.
To design a water softener one must understand that when pure water is produced by re-
verse osmosis (this applies to all manufacturers) waste water (concentrate) is also pro-
duced and this water was treated by the water softener too. To provide for this extra water,
the required output rates are doubled. Also, a safety term is included for water hardness.
In our example:
pure water output x 2 = 240 kg/h (530 lbs/h).
Here we are using an AC 2101. It has a capacity of 100,000 litres for 1°dH.
A safety term of 5°dH is added to the raw water hardness of 16°dH to yield:
total pure water output:
240 kg/h (530 lbs/h)
capacity of softener: 100000 litres / (16°dH + 5°dH) = 4760 litres
time before regeneration: 4760 litres / 240 litres/h = 19,8h
SOLUTION TO EXAMPLE 1
According to the foregoing example the resins must be regenerated after ~ 20 hours.
IMPORTANT: During the periods of regeneration (approx. 2 hours) no treated water is
available for air humidification.
For questions about computation of humidification rates please contact DRAABE Ottawa.