North Ridge Pumps – Digestate Transfer Pump for AD Plant Reduces Fertiliser Use
An anaerobic digestion plant operator contacted North Ridge Pumps who were looking to reduce fertiliser use, and utilise digestate throughout their farm.
Digestate is an excellent fertiliser containing all the nutrients and micronutrients required for successful modern farming, including nitrogen, potassium and phosphorus. What’s more, none of these nutrients are lost during anaerobic digestion, so farmers can close what’s called the nutrient cycle and reuse these essential minerals.
What our client wanted
They wanted to improve the transfer rates from their digestate pond to a nursing tank at their anaerobic digestion plant.
The liquid being transferred was mechanically-separated anaerobic digestate which contained screed at less than 1mm and only 5% solids. The mixture also contained a small amount of sand.
They were struggling to achieve a flow rate of 100m³h, and wanted to double this up to 200m³h. The digestate transfer pipeline was 300m long and fed into a nursing tank, as well as into digestate tanks as a feedstock or seed for future batches.
They were extracting the digestate liquid from a lagoon 4m in height and 18m away. Their objective was to double their existing flow rate and hydraulically mix their lagoon, they were looking for a heavy duty transfer pump to achieve this.
What was our specification?
Here at North Ridge Pumps, our wide-ranging expertise means we can specify from a wide range of pumps for a variety of industrial and commercial applications.
Moreover, we’re not limited to a single pump technology. Our know-how enables us to offer a bespoke solution, not something just picked off the shelf. This means we can select the most appropriate pump for any application at the lowest lifetime cost.
For this demanding application, we specified our XR625, and built and supplied it in just over 6 weeks. This is a 6” self-priming pump manufactured from ductile iron and hard faced seal unsusceptible to solids such as sand for this application.
Our pump is designed to deliver a digestate transfer flow rate of 200m³h with only an 18.5Kw motor. To maximise output flow, we advised the client to run the pump at 60Hz via a frequency inverter to achieve the required flow and pressure.
Our XR pump range
These are heavy-duty self-priming pumps which are solid handling, efficient and extremely durable. This is thanks to the armoured volute which surrounds the impeller, improving pump efficiency and protecting the pump casing from wear.
What’s more, the XR’s double curved impeller helps improve pump efficiency. For example, in this particular application, the existing pump achieved a flow rate of just 100m³h with a 25kw motor. Our new pump delivered 200m³h with a motor power of only 18.5Kw.
Protected against corrosion
Another important consideration was the properties of the digestate itself. It can vary in quality and be very corrosive. So when selecting a pump type, we had to make sure that all internal parts were easily accessible and aren’t held in place by screws which can corrode over time.
Our XR pump series has design features including oversized inspection ports, and no internal screws in the pump unit.
Another clear advantage of our XR range is that traditionally self priming pumps have a wear plate covering the impeller which is replaced as it wears.
The issue with this design is that when the wear plate is replaced pump performance is not restored to that of the original design as the casing has worn. Our range features an armoured volute covering the impeller which when replaced ensures the pump works to the original performances.
If you have an application needing smooth transfer of fluids, viscous liquids or solids and don’t know which pump is best for you, talk to North Ridge Pumps and get expert help and advice.
