Honeywell UDC 3300 manual Carbon Potential, Introduction Features

5.22 Carbon Potential

Introduction

Features

Figure 5-6 shows a UDC 3300 controller being used to control the carbon potential of a furnace’s atmosphere. A carbon probe consisting of a ZrO2 sensor and a thermocouple (to measure the temperature at the sensor) provides two inputs to the controller. The microprocessor-based controller computes the atmosphere’s actual carbon potential from these two inputs and compares the computed value with the desired setpoint. As an on-off or PID control algorithm determines the controller output necessary to keep the actual carbon potential at the setpoint. Usually only one output is used to add more or less enriching gas (typically natural gas) to the furnace’s base atmosphere, which has a relatively low carbon potential.

The enriching gas then raises the carbon potential to the desired level; however, there are occasions when it is necessary to add dilution air to lower the carbon potential instead of enriching gas to raise it. In those instances, a second output from the controller provides this function.

When proportional control is used, a different set of PID tuning constants is used for the dilution air than those used for the enriching gas.

•Direct calculation of carbon percentage with seven different manufacturers’ probes

–Advanced Atmosphere Control Corporation (AACC)

–Corning

–Cambridge Instruments

–Marathon Monitors

–Furnace Control Corporation

–MacDhui (Barber Colman)

–Bricesco

•± 0.02 % accuracy

•No nomographs—no mistakes

•Two controller outputs are available for duplex control.

•Probe temperature input type is selectable from complete input menu.

•Three different local setpoints—standard feature

•Duplex control with second set of PID constants for dilution air control

•Process factor adjustment capability

•Automatic sooting warning via flashing display

•New Dewpoint algorithm is available. Range: –50 °F to +100 °F

•New % Oxygen algorithm is available. Range: 0 % to 40 %

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