Loy Yang mitigates beater wheel fires wirelessly

The Loy Yang B power station is a large, brown-coal-fired power station located in Victoria’s Latrobe Valley. Loy Yang B has two units with a capacity of 1050 MW and is Victoria’s newest and most efficient brown coal-fired power station, generating around 17% of Victoria's energy needs. It is owned by GDF SUEZ Australian Energy (70%) and Mitsui & Co (30%). In 1995, Loy Yang B was the world’s first coal-fired power station to gain quality accreditation to ISO 9001 and the first Australian power station to gain environmental accreditation to ISO 14001. Loy Yang B employs up to 152 full-time staff and another 40 contractors.

Loy Yang B is supplied 24 hours a day with raw brown coal from its adjacent mine. Four giant bucket-wheel excavators, called dredgers, operate 24 hours a day in the Loy Yang open cut mine, feeding coal directly to the power station silos via a conveyor belt.

The incoming coal is fed from the silos to the coal milling plant where it is partially dried by flue gas from the boilers before being fed into the beater wheel to be pulverised and dried before it enters the boiler furnace space. The beater wheel breaks down the coal into fine dust particles the size of talcum powder, which are then blown into the partial-separation firing boiler to fuel the furnace fire.

The beater wheel stands three metres high, weighs 28 tonnes, spins at approximately 490 revolutions per minute within the mill, and operates in temperatures around 320-400°C. Under certain operating conditions, a localised fire can occur near the face of the beater wheel which can result in costly downtime and repairs.

A decision to install temperature-monitoring equipment near the face of the beater wheel was taken by engineering staff. They needed to monitor the beater wheel temperature, get that data into their existing monitoring system, and prevent localised fires on the beater wheel. Because of the severe operating conditions and the difficult installation location, a wireless system was deemed the only method capable of achieving a reliable and suitably flexible solution.

After an in-depth investigation and a review of available technologies by engineering staff, the IECex-rated Oleumtech wireless battery-powered sensors and wireless gateway I/O products were selected. These products were supplied by Automation Group, a group of companies that specialises in providing electrical and automation products, support and technical services to the utility, mining and energy sectors as well as contractors and integrators.

An embedded thermocouple device was installed near the face of the beater wheel. This was connected directly to the Oleumtech TC-1 thermocouple wireless sensor which is a self-contained, battery-powered temperature measurement solution. The TC-1 Thermocouple sensor is made especially for remote, rugged environments without access to mains power, and where solar is not an option, and can be operated in a hazardous environment with or without the enclosure and without the risk or fear of causing an explosion. It is therefore particularly suitable for monitoring flares, kilns, gas turbines and other hot industrial processes.

The Oleumtech TC-1 wireless sensors transmit data about the temperature that the beater wheel is exposed to. It also transmits the sensor’s battery voltage and wireless strength (RSSI) data to an Oleumtech DH-2 wireless gateway installed at the engineering office. The DH-2 gateway then connects to an existing DCS via RS232/485 Modbus.

“With the required temperature data being fed directly from the face of beater wheel to the DCS system, it is expected that downtime and repairs due to unforeseen temperature levels will be kept to a minimum - if not totally eliminated,” said Oleumtech Product Specialist at Automation Group Graeme Lane.

Future system expansion and the addition of other types of battery-powered wireless sensors and wireless I/O into the existing network will be easy using the Oleumtech wireless system. This is because the Oleumtech wireless system can operate point to point and point to multipoint, as well as peer to peer using multiple gateways to interface to other existing PLCs, RTUs, or DCS anywhere around the plant. This could include not only the addition of more thermocouples, but also sensors for air temperature, pressure, levels, flows, RTDs and cathodic protection.