Evaluating Trend Displays - ABB ProKiln GAC400 Operating Instruction

104 ProKiln GAC400 PROBE GAS SAMPLING SYSTEM | OI/GAC400-EN REV. A
... 11 Maintenance
... Maintenance work

Evaluating trend displays

Introduction
Irregularities of cooling-water rate and cooling-water
temperature may indicate various errors. Common reasons for
an increase or drop in measured values may be, for example,
inadequate cooling of the heat exchanger or inadequate delivery
rate of the cooling-water pump.
Trends are an important basis for understanding
process/equipment relation and an important tool when service
is offered remotely. The system has a 60-day csv format data
recording (Last in, last out) file in the data storage dongle.
Instructions
Perform the following steps to evaluate trend displays:
1. Open the wanted trend menu.
Path: Menu ► Trend Water
Path: Menu ► Trend Heat in
2. The Trend Water menu will show the important data
connected to the probe cooling.
• Green – T10 tank temperature
• Yellow – T11 water cooling forward
• Blue - T12 water cooling return
• Red – F12 Water cooling flow
• The system must be able to maintain the water tank
temperature below 75°C.
• The water flow must be stable above 90 l/min
• The water-cooling temperature return will change
depending on process and if scaling or build-up occurs on
the probe.
3. The Trend Heat Input menu will show how much heat is going
into the probe. This is done by measuring the temperature
difference between T12 water cooling return and T11 water
cooling forward. As long as the water-cooling flow F12 is
constant the difference will represent the heat input to the
probe from the process.
The Heat Input can be used to evaluate how much material is
building up around the probe or how fast scaling occurs on
the probe surface.
If a build-up of material occurs, it can be seen in a lower Heat
Input compared to normal in the entire period the probe is
inside the kiln. Often when the probe is retracted, the build-
up will be scrapped-off and the probe will be relatively clean.
If scaling of material on the probe surface occurs, it can be
seen as a high Heat Input right after the probe enters the
kiln, and gradually lowering as time passes. Often when the
probe is retracted, the scaling will stay on its surface.
If the Heat Input default value set to 25°C (Parameter input
Alarm setpoint menu on page 33) continues to raise after the
probe enters the kiln, the probe will be automatically
retracted.