On a remote farm, sustainability is a business as well as an environmental choice and it has to work faultlessly. The right pump can make all the difference, as Borger proved
Henry and Esther Rudge's 320 acre Ballingham Court farm includes 200 ewes, more than 100 cows and various arable crops farm in the Wye Valley area of Herefordshire.
While it lies in a designated Area of Outstanding Natural Beauty (AONB) there are disadvantages, admits Esther.
“We’re almost landlocked here by the River Wye, with poor road links and ever-tightening restrictions on what we can and can’t do, so it was vital that we became as sustainable and self-sufficient as possible.
“NVZ (Nitrate Vulnerable Zone) regulations were taking more effect and we considered building a pad to store manure but then thought, why not enclose it, put a roof on it and gather all the methane for good use?”
The solution was an 80KW AD plant, managed by their son Monty, an agriculture graduate (pictured) from Harper Adams University, which provides a sustainable solution and an opportunity to export most of the farm’s green energy to the National Grid.
However, the pump on which the plant relied was unable to handle the 11% dry matter thickness of the digestate being discharged.
Börger Pumps quickly helped out with a temporary solution until a larger unit could be installed. The firm also provided the Powerfeed system and Multichopper macerator at the front-end of the process.
The Powerfeed mixes and homogenises the feedstock of fruit, manure, maize and chicken litter – regardless of the content’s variability. Raw material feeding technology guarantees safe and reliable processing of solids from 4-5 tonnes per hour, up to nine tonnes per hour, if required.
“Despite the inevitable foreign objects (such as wood) that get caught up in straw, the Powerfeed will handle it,” says Esther.
We’ve seen first-hand that standard equipment simply cannot cope with certain feedstocks or the inevitable variations in what goes in to a digester
Connected by a Börger circulation pump, the P500 Multichopper boasts a perforated disk chopper with a robust central high-performance rotating blade holder, benefitting from reversible blades. The multiple blade cutters are automatically adjusted by the Börger MCA (Mechanical Cutting Adjuster). Throughput volumes are up to 400m3/h (1760 usgpm).
Börger has also supplied a bespoke control system to give a fully automated feed-in system. A PL200 Börger pump provides continuous feed for a 10m3 buffer tank. As the tank approaches capacity, the system typically performs a 5-minute feed cycle, pumping feedstock from the Powerfeed through Multichopper macerator and into the digester. Time length for a feed cycle can be adjusted for certain feedstocks in order to maintain gas levels. This prevents fluctuations in temperature that would prevent the AD process from operating at optimum levels
Load and flow sensors also enable Börger to monitor the equipment remotely so that they can see at a glance via a smartphone or pc that the feed/not-feed set-up is working as it should be. It operates at around 1Bar, with no great head of pressure to overcome.
Explains Esther: “We’ve achieved our aim of becoming increasingly sustainable – and generating a new income stream. In addition, the liquor we tanker on to our land is very rich in nutrients and good for our soil, as is the digestate.
“Even though our AD plant isn’t on a large scale, we’ve seen first-hand that standard equipment simply cannot cope with certain feedstocks or the inevitable variations in what goes in to a digester. Tough, industrial-type equipment is a must.”