NORMAL OPERATION
In order to consume the minimum quantity of product, water is normally used to start
up the equipment until the required running conditions are achieved, whereupon the
water can be easily drained and replaced by the product.
The product will have quite different physical properties from the water and will
cause the feed pump to perform differently. Some adjustment of the back pressure
valve will be required to obtain the desired conditions. If the gear pump option is
fitted, the pump speed will also have to be adjusted, however, the progressive cavity
pump option will maintain a steady flow rate.
Before start up, decide what product throughput and temperature (T1) are required.
Normal throughput is 10 litres per hour and the two holding tubes supplied are 2 sec
and 15 sec, calculated at this throughput. The flow rate is determined by simply
collecting the liquid emerging from the back-pressure valve in a measuring cylinder
for a timed period.
Every time the speed of the pump is adjusted, the flow rate changes and every time
the back-pressure valve is adjusted, the flow rate changes. The correct setting of back
pressure is that which will prevent product in the heat exchanger boiling at the
temperature at which it is being processed.
A setting of 4.0 bar will cope with any temperatures up to the maximum capability of
the unit (150°C). It is not necessary to apply any back pressure when working at
temperatures of less than 100°C as this will cause unnecessary wear of some
components in the system.
Set up:
1. Bring the unit up to temperature using water as the product. To do this follow
the procedure given in the COMMISSIONING section of this manual, but set
the temperature on the controller to the desired operational set point.
2. When the required operational temperature has been reached, re-adjust the
pump speed and back pressure valve until the flowrate is 10 l/h and the system
pressure is 4.0 bar.
3. The unit is now ready to process the food product. Remove the flexible tube
(returning water from the back pressure valve) from the feed tank and direct to
a suitable receptacle. As the water level in the feed tank falls be prepared to
replace with the product to be treated. It is desirable not to allow any air to be
pumped into the heat exchanger so do not allow all of the water to disappear
from the feed tank before adding the product. When a small amount of water
remains in the tank, add some product then leave to drain for a few seconds
and add more product - in this way the liquid in the tank becomes more
concentrated until none of the water remains and there will be no air allowed
into the exchanger. Fill the tank with product.
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