Digital Communication in Sample Conditioning Systems Envirotech Online

When extracting the process gas sample, process-related impurities such as particles or moisture are inevitably also extracted. These can affect the measurement results or damage the measuring cells. The gas sample must therefore be prepared before entering the analyzer. To remove moisture, the gas temperature in the sample gas cooler is lowered below the dew point. The resulting condensate is discharged.

The chiller is controlled by a microprocessor. Exceeding or exceeding the set warning range (e.g. after switching on) is signaled both by flashing LEDs and by the status relay. The status output can e.g. B. can be used to control the gas sampling pump to allow gas flow to be activated only when the allowable cooling range is reached. By connecting a humidity sensor, the controller can be extended to monitor condensate breakouts.

Until now, the measured temperature of the cooling block could be transmitted via an analog signal 4 – 20 mA. As digitization continues to progress rapidly, Bühler Technologies GmbH will in future offer the more advanced Modbus RTU communication protocol as an option for all sample gas coolers with solid-state cooling elements. This digital interface represents a higher authority, such as B. The control system has extensive information about the sample gas cooler.

With the option of the Modbus RTU digital interface, the user now has direct access to process and diagnostic data, for example the current temperature of the cooling block or information about a possible temperature error if this is outside the target range. If a humidity sensor is connected, eg B. also a humidity breakthrough can be determined directly from the control station. All settings that could previously be made via the menu on the display of the sample gas cooler can now be made remotely from the control room and directly during operation. Condensate pumps can be switched on and off again as needed, the cooling block temperature setpoint can be adjusted and alarm thresholds can also be set remotely. New features are also the chiller utilization output (in %), which is useful for evaluating the performance limit, and the device runtime output, which can be used to implement maintenance intervals.

Modbus RTU is considered a very robust interface and allows remote access to the sample gas cooler from Bühler Technologies GmbH to control and monitor the current status, robust and reliable communication between field devices and the control system and thus supports the safe and continuous operation of the process and plant.

The following sample gas coolers are available with Modbus RTU:

  • Electric gas coolers
  • TC-Double
  • TC-Double+
  • TC-MIDI
  • TC-MIDI+
  • TC-MINI
  • CT standard
  • TC-Standard+
  • RC Gas Cooler 1.1
  • Gas Coolers 1.2+

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