EtherCAT based system treats commercial waste efficiently

As the volume of greasy waste being produced by a variety of commercial enterprises grows, the environmental impact and cost of dealing with this type of waste in conventional ways continues to escalate.

To assist in addressing this challenge, a pilot plant that utilises new Omron NJ control and EtherCAT technology for processing and treating greasy commercial waste, including from restaurant grease traps, has been built in the Melbourne suburb of Dandenong South by Organic Environmental Solutions (OES), which is part of the K S Environmental Group.

The company collects highly caustic greasy waste from a range of customers and then treats it via an automated process whereby by-products such as soil conditioners, fertilisers and organic lime are produced that can be recycled, thus providing additional income streams.

Final effluent is treated to a standard that is approved by South East Water for discharge to the local sewer main, thus avoiding the high costs of dumping to landfill.

K S Environmental's engineering services manager, Darren Souter, advises that some 90,000 litres per day of grease trap waste comes into the plant for processing, and that in 2011 around 91,665 tonnes of grease trap waste was produced in Victoria.

"We are a small family owned business that is taking on the big multi-nationals in the waste processing industry through a strong focus on cutting edge technology that could potentially change the way greasy waste is handled in Australia," he said.

"A centrifuge is used to separate out various elements of the waste instead of utilising conventional settlement ponds, thus providing significant environmental and cost benefits. The building that houses the plant, including 16 large silos, operates on negative air pressure to control odour via a wet scrubber which cleans the air and discharges it to the atmosphere."

 EtherCAT is  the way of the future for plant and process control

The entire plant is run on EtherCAT, which is supplied by Omron Electronics and provides a control communications platform designed for industrial process plants.

Omron's Chris Probst says that EtherCAT is mainly used for field networks and is the way of the future for plant and process control.

"It is essentially Ethernet for industrial automation control, but it overcomes some of the limitations of Ethernet. A big advantage of EtherCAT is that it can mix star topology with daisy chain topology, which provides a lot of flexibility in plant design and layout, as well as reduced installation time and cost," Probst said.

"EtherCAT provides a fast network that achieves high synchronisation accuracy by using a distributed clock mechanism with standard Ethernet cables and connectors, and automatic address assignment for nodes.

"This is an inter-system network that eliminates the barrier between motion networks and field networks, thereby contributing to a reduction in design works and a shortening of task times. It is a high-performance field network that is able to connect drive devices, intelligent sensors and I/O devices using Ethernet technologies.

"The OES ground breaking pilot plant needed an industrial FieldBus network that allowed for large expansion, and EtherCAT provides this.

"The company recognised the advantages of EtherCAT over DeviceNet, including the future proofing that would be provided, and that DeviceNet would be 30 percent more costly. The main aim was design flexibility to provide a leading edge process with leading edge technology controlling it."

Probst explains that Omron's CX-Supervisor SCADA system communicates over the information network to an Omron NJ controller. The NJ is the EtherCAT Master, controlling the process via the various Slaves on the EtherCAT network.

The screen in the plant operations room shows all processes that are running in real time.

The screen in the plant operations room shows all processes that are running in real time. 

An Omron Sysmac CJ2 PLC controls the centrifuge that is used to separate the raw material, and an Omron NS HMI (human/machine interface) forms part of the PLC control system.

"CX-Supervisor performs monitoring and supervisory tasks of the complete process. It provides powerful functions for a wide range of PC based requirements and offers the ability to create flexible applications and extend functionality. Past data can be overlaid with new data to compare one period with another.

The entire plant is run on EtherCAT which can mix star topology with daisy chain topology.[The entire plant is run on EtherCAT which can mix star topology with daisy chain topology. ]

"Machine control is based around the NJ EtherCAT Controller, which is a completely new Sysmac automation platform that can seamlessly integrate up to 64 axes of motion control with the control functionality of a PLC.

"New Sysmac Studio software integrates configuration, programming and monitoring based on popular programming standards PLCopen and IEC 61131-3.

"EtherCAT uses industrial standard Cat 5 or higher Ethernet cable to connect devices to the field network, which has nodes throughout the plant that interface with tank level sensors and control valves to allow product to flow between process stages.

"There are 10 variable speed drives throughout the plant which can be monitored and controlled by the EtherCAT Controller."

In the plant operations room a large screen shows all processes that are running in real time. All tank levels, flow rates and set points are displayed as well as the entire SCADA process.

Logging, trending and historical reports are provided, and alarms are automatically activated in relation to any issues that need addressing.

Probst says the NS HMI has enhanced graphics capabilities including a large library and high definition TFT colour touch screen. A new gateway function is also included to transfer data between connected devices. There are also three smaller screens.

The first shows the raw material settlement process following intake, and the second shows centrifuge preparation. The third screen provides the office with readings from the PLC on the centrifuge during centrifuge operation.

An iPhone can be used as a modem with a laptop computer to remotely control the plant processes. According to Souter, the pilot plant is providing a range of significant benefits including both cost control and environmental protection.

"Our customers are recognising the cost benefits of utilising this environmentally friendly commercial waste treatment process compared with sending their greasy commercial waste to landfill," he said.

"There are also substantial cost benefits for OES through processing efficiencies as well as the benefit of additional income streams from by-product production and recycling.

"Introduction of this new cutting edge technology means that only four-to-five people are required to operate the plant and these people have been involved from the start in helping to design and build the operation.

"Environmental responsibility is central to the company's operations and is reflected in our triple bottom line approach to accounting practices."