RNG Controls System Project

Helle Engineering developed the RNG Controls System Project in Morris, Minnesota from the ground up. The project consisted of 3 dairy farms sending H2S free methane to a central facility where the gas would then be scrubbed of CO2 and injected into the pipeline for distribution. Over the course of 2 years, we developed the operator interface, PLC logic, automated alarm features, installed fire and gas protection, cloud-based historian access, and are still supporting them to this day. Even when a natural disaster struck, we were there to help get our client back up and running as quickly as possible!

Throughout a 5-month period we developed HMI graphics for 3 operator consoles and 4 HMI’s (one for each site). The operator consoles used Rockwell’s FactoryTalk SE software and the HMI’s used FactoryTalk ME, however we came across incompatibilities in the platforms. The incompatibilities occurred when creating graphics in one software that did not allow those graphics to be used in the other. This is inefficient; therefore, we devolved a way to import graphics into both platforms using the source code in the graphics. This development significantly reduced the time it would have taken to produce the graphics normally.

Using a pre-designed control narrative Helle created the BPCS (Basic Process Control System) involving motor start/stop, valve control, cascade controls, alarms, safety interlocks, and communication logic between vendors. We also developed a custom function block in the PLC for FIFO (First In First Out) logic. This logic was tested in a FAT/SAT and has been working without any issues since we commissioned it.

One feature our customer wanted to have an automated system that would send email or SMS alerts when certain alarms would be active. Unfortunately, the SCADA software we were using did not have this capability therefore we came up with two solutions to accomplish this task. One way was using EWON custom scripts and the other was using Sensaphone technology. Ultimately our customer decided to use the Sensaphone rather than the EWON scripts.

Safety is one of Helle’s biggest concerns during every project. Our top priority is to ensure there is no harm to people or the environment. We developed fire and gas logic to evacuate personnel, clear toxic fumes from indoor areas, and stop the plant during a leak. We also incorporated fire beacons and wobbler horns to alert personnel so they can evacuate the process area. This was done by integrating Honeywell fire and gas detection panels into the control system which will display to operators which area the fire or gas leak has been detected.

At any facility collecting data is a necessity for recording and troubleshooting purposes. In the biogas sector our clients need to report methane and flare gas data to the government. For our client to do this efficiently Helle used our Micro Historians to collect data then send it back to a central location. At the same time in the central location the data is being processed into a cloud-based historian service which allows our client’s recorders from a remote location to access the data. In the event the link between the cloud-based service and the local data collector becomes broken (i.e., loss of power, network failure) the data collector will buffer any data until the link can be re-established ensuring no data ever gets lost (see our Micro Historian Project for more information). This helped our client achieve a Carbon Intensity (CI) score of -254.94 gCO2e/MJ, the lowest ever issued by CARB. 

Our client was so pleased with how well this facility turned out that they signed a 24/7 support contract for this facility and their others across the country. We still support this site, and it is one of our clients’ most efficient and least problematic sites.