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In the compressor room of a biogas plant of every plant module, a remote I/O system in zone 1 collects all sensors and other signals from the hazardous areas

Image: Turck

Fieldbus & Networking Automation solution for energy sector

Aug 31, 2016

Efficient energy use requires intelligent measurement, management and control of production and auxiliary processes in combination with energy-efficient products. The article highlights how the automation industry has picked up on these aspects, offering a range of products and services that span many different industrial sectors.

Some industries endure the challenges that energy applications must persevere on a daily basis. Extreme temperature, rain and moisture, and even exposure to the sun can wreak havoc on sustainable energy applications. Turck provides robust solutions focused on keeping these systems running.

A Swedish company, who is an expert on biogas upgrading plants, can upgrade biogas from fermented household garbage and other organically waste very efficiently into methane and CO2. The company recently improved the maintenance work for its gas plants with a new remote I/O system, which met all their demands with Turck’s excom system, used in hazardous and non-hazardous areas.

A sustainable approach

Almost every human activity creates waste. But waste can be a valuable resource. Excess agricultural produce, manure, waste water sludge, household and restaurant waste are the perfect raw materials for biogas production. The biogas can be upgraded to pure bio methane, which is used as vehicle fuel or for injection into the natural gas grid. The digestion of organic solids produces raw biogas that contains 50-70% bio methane, 30-50% carbon dioxide and traces of sulphur, nitrogen and oxygen.

The gas plants take raw biogas and upgrade it to pure bio methane. With its chemical absorption process, called CApure, the plants remove carbon dioxide and hydrogen sulphur from the raw biogas. This increases the efficiency of the biogas plant and improves its eco balance.

Turck has its remote I/O system excom, which can be mounted directly in zone 1. Additionally, the excom status LEDs are easily visible through the window of the stainless steel box the excom is mounted in, allowing easy identification of potential problems.

In the compressor room of a biogas plant of every plant module, a remote I/O system in zone 1 collects all sensors and other signals from the hazardous areas. This aids the customers and prevents the shutdown of the plant module and de-gassing of the compressor room. A lot of time, work and money is often required for minor problems such as, a wire break, which can be prevented.

Reason for system change

As per the engineers of the plant, the easy maintenance of excom was the major reason for the system change. They elaborated, “The well-visible LEDs and the easier maintenance through hot swap in run were our main reasons for excom. Besides that, excom matches aesthetically. We try to build everything in stainless steel. With its designated stainless steel housing, excom fits like a hand in a glove.”

During the process, other solutions in the Turck portfolio were found to enhance their gas plant. In the outdoor parts of the plant, at the CO2 absorption tower, a fieldbus system had to connect several valve indicators to the Profibus of the PLC. Modular fieldbus I/O system BL67 with a temperature range up to 40°C can be used outdoors, even in harsh Swedish winters.

A Chinese Power Engineering Company began expanding its plant’s capacity with another two 135 MW units for processing lower quality coal. Extensive transport system run through the entire plant in order to transport the coal from its repository to the coal mills that precede the burning kilns.

This is why the plant designers made great demands on the automation solutions being used. Ultimately, countless sensors and actuators spread all over the plant area have to be operated despite dust, dampness, vibrations, noise or electromagnetic interferences.

Going the modern way

A conventional automation architecture would not have met these demands, which is why the designers chose a modern fieldbus system for the signal transmission between the PLC and sensors/actuators. The proper fieldbus system – featuring a modular design and IP67 protection – not only guarantees interference-free communication between all devices involved, but it also provides a high degree of data integrity, protection against vibration and extensive diagnostic functionality.

In order to guarantee reliable operation in spite of dust and vibration, plant designers decided not to abandon IP67 protection – although each and every fieldbus station was to be installed in a control cabinet. Turck’s fieldbus system convinced the plant designers with another option: single I/O modules can be swapped in full operation.

In this way, BL67 allows plant operators to replace broken I/O modules and avoid expensive downtime. Short-circuit protection and distinct diagnostic functionality that provide a quick status overview complete the system’s comprehensive safety equipment. Thanks to its modular design, the BL67 system can simply be expanded if necessary – whether digital, analog, temperature or other signals need to be integrated.

The modular I/O stations transfer all the analog and digital signals that reflect the transport system’s status – whether rate of feed, offset, distension, cracks or fill level data. The fieldbus stations are connected to the higher level PLC, via DeviceNet. After evaluating the obtained data, the PLC submits the plant’s status to the management information system (MIS).

Reduced hardware needs

The application of fieldbus technology avoids the use of a large number of cables, cable routes, terminal blocks, and marshalling racks as well as costs of laying of cables, cable connection, and checking. Reduced hardware needs result in easier project engineering, fewer engineering hours, and less documentation. Also, upgrades become more economical. Looking into this, Turck provides robust solutions focused on keeping systems running and helping collect and produce energy quickly, efficiently, and with minimised downtime.

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