Danish manufacturer Landia has kept this Shropshire dairy farm's AD plant in the loop
A Shropshire dairy farmer has highlighted how his new slurry pump now works wonders at his anaerobic digestion plant.
The farmer remembers the day when his sorrow turned to joy over what he thought was a faulty flowmeter â only to later discover that it was the output created by a new slurry pump that had sent readings soaring to numbers previously not recorded by the siteâs instrumentation.
âHe didnât believe it at firstâ, said Paul Davies from pump manufacturers Landia, âhe wasnât happy to begin with but didnât mind admitting later that he thought it had been his flowmeter playing upâ.
The reason for his welcome surprise was that a new pump from the Danish manufacturer had produced an unprecedented throughput.
Some had told the farmer that it wouldnât work for the very tough anaerobic digestion (AD) or feedstock application â and initially he agreed with them â but they were all proved wrong.
âMaximum Outputâ
Davies added: âPrior to the installation, he couldnât run at maximum output, which was very frustrating, but now all of a sudden, what was previously taking an hour to process has been reduced to just 25 minutes â enough to make any farmer happyâ.
Designed for a very specific application, directly on from the digestate feeder, the farm and its AD operation were almost immediately able to reduce the cost of its energy-rich feedstock.
Established over a century ago, the 2,000-acre farm first invested in Landia slurry pump - a submersible 7.5kW - in 2003, which is still in operation.
It continuously mixes what has now become a valuable feedstock, rather than a waste that must be dealt with.
Investing in its own AD plant four years ago, the farmâs annual electricity bill was around ÂŁ55,000 â but the 1.5MW of power now produced easily covers that now historic outlay, with a healthy surplus sold on to the National Grid â and excess heat put to good use for drying the farmâs bedding.
The feedstock of cow slurry, maize, rye and sugar beet is topped up with fruit and vegetable food waste from local wholesalers â which after being held in a 500m3 buffer tank, is pumped to a heat treatment tank, before it is sent to the primary digester.
The resulting digestate is pumped to two storage tanks of 240m3 and 500m3 â before the final liquor is sent to the farmâs slurry lagoon.
âBenefits the entire processâ
The high pressure 22kW Landia Chopper Pumps are designed with an external knife system that stops any solids from entering the pumpâs casing.
Throughout the operation, the Landia pumps at the farm - which all run on variable speed drives to maximise the life of the impellers - and continuously reduces particle sizes, which benefits the entire process.
In total, there is now one mixer and nine pumps from Landia, including three longshaft designs and four dry-installed pumps.
Paul Davies added: âWeâve worked with the farm for a long time and wanted to help them optimise their new AD process. We were faced with several challenges, but weâve put our heads together and were determined to achieve the required result.
âIn the end, we found a way of boosting the pumps with an extra loop in the pipework. âLive digestateâ can cause problems for many pumps and pipework, with so much extra gas being released, but our design and the robustness of the pumps means that nothing has tripped out,â he said.