MUST HAVE. SHOULD HAVE. COULD HAVE. Module # 100. Batch Control Software. PAM & CPM Services. FBM. Fieldbus. Ethernet TCP/IP. 1. Measurement Devices Scales & Flowmeters. Qi Performance – the calculations and theory. Objectives:
Module # 100
In order to control at higher Flow rates - You need Speed !
Qi > 333 A/D conversions/s (Digital is SLOWER!!)
Qi Comparator responds within 20 mS (Flowmeter < 5 mS)
We have a Constant Material Flow rate of 100 kg/s
Our Comparator updates every 20mS or 50 x per second
Our weight will change by 2kg each time the comparator “compares”
Our theoretical error limits will then be within plus, minus 2kg
At Feed Flow rate of 100 kg/s
+2kgQi Performance – the calculations and theory
Imagine a Spill value of 200 kg
ie the material takes 2 seconds to travel from the Control Valve to the Scale
If the Flow rate changes between feeds by +20%
We can expect be over feed by roughly 40 kg! The High Flow rates have magnified the errors due to Flow rate variations.
This is why we have had to use two speed feeds in the past.
SpillEffect of Flow rate variations