Fires in a coal-fired plant's fuel system rarely happen out of nowhere. There is usually a sign hours or even days earlier: a slowly rising temperature inside a bunker, at a pulverizer outlet, or in a fuel tank. Plants that monitor these points have time to act before the problem grows.
Coal in bunkers and stockpiles keeps reacting with oxygen in the air. This reaction releases heat little by little, and if the heat cannot escape, the temperature deep inside the pile can keep rising until spontaneous combustion occurs. The risk is higher for the low-rank coal widely used in Indonesia, especially when coal sits in the bunker for a long time while the unit runs at low load. A temperature sensor with a long probe reaching into the bunker can catch this rise early. The same applies to biomass silos, since wood pellets and palm kernel shells can also self-heat in storage.
In the pulverizer or coal mill, coal is ground while being dried by hot air, then carried to the burners. The temperature of the air and coal dust mixture at the mill outlet is one of the parameters operators watch most closely. Too low, and the coal is not dry enough and the mill can choke. Too high, and the risk of a fire or explosion inside the mill increases. Mill outlet temperature is therefore usually controlled automatically by adjusting the mix of hot and cold air.
Sensors at the mill outlet work in a harsh environment, since the coal dust moves fast and is abrasive. They need a wear-resistant thermowell and should be placed where they read the temperature of the mixture, not just the temperature near the wall.
Fuel oil tanks, such as high-speed diesel (HSD) for unit start-up or marine fuel oil (MFO) for support firing, also need temperature monitoring. For MFO that has to be heated to stay pumpable, the tank sensor controls the heater so the fuel is neither too thick nor overheated. Combined with level measurement, temperature data also helps calculate fuel volume accurately.
All these measuring points are usually connected to the DCS through temperature transmitters with a 4–20 mA output. Operators can then follow temperature trends in bunkers, mills, and tanks from the control room and receive alarms before conditions become dangerous.
CV. Rach Tekindo Makmur supplies Temperature Sensors & Temperature Transmitters for a wide range of industrial instrumentation needs. If you need sensors, transmitters, or consultation on configuration and installation for your temperature system, contact us on WhatsApp at 0877-8620-5656 to discuss your technical requirements and request a quotation tailored to your application.
