IDM ¦ Technology/IT
Improved CIP
Switchable ring distributor
Author: Joachim Löw, Milkron GmbH
The switchable ring distributor was awarded the Dairy
Technology Award by "IDM International Dairy Magazine"
as part of the 2021 tender. Meanwhile, the development
of the patented function is well advanced. It is
worth taking a look at this.
When planning and implementing a CIP plant for a dairy, the
cleaning areas that require the largest electric power to convey
media are often tanks. In classic storage tanks, the distribution
of cleaning agents usually takes place via centrally permanentinstalled
spray balls or comparable components at the top of the
tank interior.
The size of the ball depends mainly on the tank diameter. As
a rule, 2 to 2.5bar overpressure is required for distribution inside
the tank at this point. Depending on the tank height, a CIP supply
pump often has to deliver about 4.5bar.
Volume flows of e.g. 20-30m³/h and more are not uncommon
for larger storage tanks, but rather classic. The cleaning effect in
the tank is not achieved by mechanical impact when liquids hit,
but by the outflowing media including their temperature/concentration.
Problems with the spray ball
If you take a closer look at the function and distribution pattern of
a spray ball, doubts arise about the efficiency and quality of this
method: The liquid is pressed through narrow holes in almost all
directions and, depending on its orientation, sooner or later hits
the wall, top or tank bottom. All areas of the tank are hit at the
same time, so that the flow is significantly higher in the lower area
and significantly lower in the upper area. During phase changes,
the "new" liquid is partly thrown directly towards the bottom,
while another part goes to the top and mixes with remnants of
the "older" liquid when it drains.
8 · May/June 2022 ¦ international-dairy.com
The spray pattern (comparable to a toilet brush) results in a
large surface area between the moving liquid and the air volume
inside the tank, so that energy is blown "into the air" during temperature
changes, which is also clearly noticeable in the ventilation.
Uniform movement, reduced flow
Already earlier the consideration arose that it would be better to
let the entire liquid drain from the upper end of the tank wall (in
a circular starting) downwards, as the movement of liquid is uniform.
This allows the overall volume flow to be reduced. When
changing phases (e.g. water to lye), the old medium is "pushed
out" more linearly from top to bottom. Mixing is reduced. During
temperature changes, significantly less energy is transferred
to the air volume; the heat goes more directly to the surfaces to
be cleaned.
In order to achieve a uniform, plate-shaped distribution of the
liquid in the upper tank, an annular gap is used, which can be realized,
for example, by means of a distribution plate. Throwing the
liquid from the center to the wall here requires significant less pressure
than with a spray nozzle. Thus, even with a larger diameter
(in tests e.g. 4.6m) 0.6bar instead of the approx. 2 to 2.5bar when
using a spray head are sufficient. This alone can save one third of
the electrical power on the flow pump.
Decisive advantages arise if the annular gap can be changed
in a defined way during cleaning: The top of the inner tank can be
washed at defined intervals. During the phase change, it is possible
to increase the throughput of the cleaning and thus to achieve
the criteria in the return flow (temperature, concentration) more
quickly. By frequently changing the gap size, the flow velocity on
the tank wall can be rhythmically changed, which increases the
effect of cleaning. In the classic circulation of lye and acid, less volume
flow needs to circulate at a narrower gap in order to further
reduce of the consumption of electrical energy.
/international-dairy.com
