Catch here
Ensuring reliable heat and power generation
Mitsubishi Electric’s automation technology delivers highly accurate control solution for anaerobic digestion plant
M
itsubishi Electric Ireland Automation Partner, Ashdale Engineering, located in Northern Ireland, has designed a highly accurate control system for an anaerobic digestion (AD) plant. The precision process control is achieved using Mitsubishi Electric automation components and is vital to ensuring continued operation of the live AD process, enabling the generation of heat and electricity that the plant operator now plans to sell to the grid. The anaerobic digester at a large farm near Armagh drives a combined heating and power (CHP) plant that heats the farm’s buildings while also producing electricity. Animal slurry, silage and additives are mixed together and the resulting biomass then is heated to produce biogas, used to power the CHP. Based in Belfast, Ashdale Engineering became involved with the project because of its specialist expertise, having worked on AD projects for over 10 years in Northern Ireland together with Mitsubishi Electric.
Accurate control
By utilising the advanced programming features of the Mitsubishi Electric MELSEC-Q Series PLC, Ashdale Engineering was able to develop an accurate and reliable control solution. Analogue flow and temperature signals transmitted from the pump house and digesters, which could be up to 30 metres away, are communicated over CC-Link via remote I/O. Interaction with the PLC takes place via a HMI communicating over Ethernet and a variety of Mitsubishi Electric variable speed drives control the system’s pumps. The solution ensures reliable heating and power generation and is now providing the opportunity for profitable export to the grid. “The AD plant has capacity for around 40,000 m³ of biomass fuel and small changes to any of the variables can impact the temperature of the biomass,” says Adrian Whitten, systems manager at Ashdale Engineering. “Floating point number calculations, made possible by Mitsubishi
The precision process control solution provided is vital to ensuring continued operation of the live AD process, enabling the generation of heat and electricity that the plant operator now plans to sell to the grid. Source: Mitsubishi Electric Europe B.V.
explains Adrian. “Again, this can kill the microbes and stop the process. Any changes in the feed have to be made very gradually and with precise control. That’s what the MELSEC-Q PLC enables us to do.”
System management
Ashdale also accounted for the AD plant’s wish to expand in the future. The MELSEC-Q Series PLC offers the needed flexibility in terms of expansion on I/O, for example to control additional drives as well as pumps, enabling the scale up of their operation and energy export to the grid. To enhance operator control, the system enables easy selection of recipes from the Mitsubishi Electric HMI and different recipe settings can be stored for changing feed parameters.
By utilising the advanced programming features of the Mitsubishi Electric MELSEC-Q Series PLC, Ashdale Engineering was able to develop an accurate and reliable control solution. Source: Mitsubishi Electric Europe B.V.
One of the crucial aspects of anaerobic digestion is temperature control, as the microorganisms that break down the biomass require temperature stability. Fluctuations above one degree centigrade per day can kill them, stopping the process and with it, the generation of heat and power. In the event that this occurs, it takes considerable time to remove and replenish the biomass to restart the AD process. In addition to offering stability, the control system also needs to be responsive, easy to use and reliable.
www.cieonline.co.uk
Electric’s MELSEC-Q Series PLC, were vital to achieve the precise control required to ensure long-term stability of the process. Combined with high resolution analogue inputs, the accuracy of calculations gives greater control, meaning continued assurance for heat and power generation.”
High resolution and accuracy are also critical for recipe control. The ratio of ingredients can change dependent on seasonality as well as adjustments for desired outcomes. “Some farmers may overfeed the AD system, or feed a recipe that is too rich,”
“The HMI’s recipe system allows farmers to retrieve feed ratio data from previous months and years, identifying how the ratio changed according to the season. This way, planning and monitoring recipes is a simple process for the farmer to manage for optimum generation and efficiency,” adds Adrian.
Monitoring data and alarms can be easily viewed from any internet-connected device and the system can be controlled remotely too. Ashdale Engineering’s system design integrates gas monitoring into a single measurement sensor, removing the need for multiple analogue devices that measure each gas separately.
The slurry pump is responsible for filling the digester, so reliability is essential, and
the torque requirement is dependent on the consistency of the slurry. This is achieved with the FR-A800 series variable speed drive. With flux vector control and providing high torque at low and zero speed, the drive features torque monitoring for quick detection of blockages. Gas feed pressure is very important for the efficient operation of the gas engine and this is achieved by the FR-D700 drives that are highly reliable and simple to set up.
“Choosing the correct variable speed drive for the application and the careful consideration of the fieldbus network that links all plant components is critical,” says Simon Murray, Variable Speed Drives product manager, Mitsubishi Electric.
Automation control systems “We have a close partnership with Ashdale Engineering and have been delivering solutions for a wide range of applications for over 35 years, and this project is an example of our successful working relationship,” says Ciaran Moody, general manager, Mitsubishi Electric Ireland.
The next stage for the AD plant operator is to expand the process and export biomethane as well as electricity to the grid. This requires an increase in the methane content of the produced biogas from 70% to 90%, the level needed for export to the grid, which will be achieved by the partnership between Ashdale Engineering and Mitsubishi Electric.
gb.mitsubishielectric.com Components in Electronics April 2021 15
Power
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54
