A Continuous Process; Figure 3 - Continuous Mixing Process - Hydronix Hydro-View HV02 User Manual

A continuous process

A typical example of a continuous process is shown in Figure 3.
In this case, a continuous mixer is supplied with material to be wetted to a pre-set
moisture content. Modulating the water feed, dry-material flow-rate or a combination of
both may be used to achieve this.
A Hydro-Skid sensor is used to monitor the output of the continuous mixer on a conveyor
belt. In some cases, it may be convenient to use a Hydro-mix sensor at the output of the
mixer, depending on mechanical arrangements.
As with many control systems of this type, there is a time lag between the control action
point - the input to the mixer - and the point at which the measurement can be made.
Hence the response time of the Hydro-View (in terms of the number of samples
parameter) should be set in accordance with the time constant of the system to prevent
unnecessary and erratic modulation of the valve controller.
Systems such as this have been used successfully in the tempering of materials such as
clay and PFA.
Recommendations for best performance
site the moisture sensor in the most appropriate place for the application -
A
LWAYS
preferably as near to the control point as possible (to minimise time lag) without
compromising the homogeneity of the material passing the sensor. The position chosen
should ensure that the sensor is covered by sufficient material at all times during
measurement and is not in an area prone to build up of waste material, which would lead
to erroneous readings. General advice on this can be found in the Hydronix moisture
sensor data sheets and by contacting your Hydronix supplier.
ensure that the sampling and filter parameters are set appropriately for the
ALWAYS
application - guidelines are given in Suggested working values (p40).
provide some means of detecting an empty belt condition when using the Hydro-
A
LWAYS
Skid sensor. In many cases, simply setting the sensor maximum voltage parameter to a
suitable value will suffice. The purpose of this would be to prevent the control loop adding
water to apparently very dry material. The alarm output relay of the Hydro-View might be
used to signal the controller in this event.
try to use the Hydro-Skid on very thin layers of material as this will give erroneous
N
EVER
readings. All Hydronix sensors work best in bulk materials.

• Figure 3 - Continuous mixing process

HYDRO-VIEW USER GUIDE D0022 REV 1.06
A BATCH MIXING SYSTEM
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