Just outside Breddorf in northern Germany, two livestock and crop farmers jointly operate an AD plant, in which the Vogelsang HiCone progressive cavity pump has dramatically cut their spare parts bill.
Plant operators Harm Drewes and Uwe Ringen had previously faced frequent and costly replacement of wear parts in their feed pump. The Harm Drewes biogas plant processes around 20,000 tonnes of feedstock each year, including approximately 8,000 tonnes of manure and solids separated from liquid manure, supplied by neighbouring farms.
With almost 75 tonnes of feedstock entering the plant every day, a high-performance pumping solution was essential. Fibres and foreign matter in the feedstock place considerable strain on system components. And with a dry matter content of 14 to 15 per cent in the digester, the pumps and mixers also have to work harder and run for longer.
With its conical rotor and stator design, the HiCone offers a long service life, low life-cycle costs and high energy efficiency. Its smart adjustment system compensates for wear and allows the pump to be adjusted to suit individual operating conditions. This keeps costly replacement of wear parts to a minimum.
Marco Blanken, an employee of Drewes and Ringen, said:
“We had to replace worn parts in the feed pump every two to three months. That’s why we replaced the feed pump with a HiCone progressive cavity pump from Vogelsang. Since then, its service life has more than quadrupled, and there is still scope for further readjustment.”
To improve efficiency and modernise the system, Drewes and Ringen installed a liquid feeding system. The solid matter feeder mixes dry solids with recirculated material from the digester to create a feed slurry. It then processes the mixture into a homogeneous suspension before pumping it into the digester.
This places considerable demands on the pump that transfers the highly viscous recirculated material from the digester to the liquid feeding system. Because of the material’s high viscosity, the long pumping distances and, in places, challenging pipework, the pump has to operate at pressures of up to five bar.
The smart adjustment system compensates for the gap that develops between the rotor and stator as a result of wear by allowing the rotor to be adjusted axially. This has enabled the plant operators to significantly reduce how often wear parts need to be replaced.
The Harm Drewes biogas plant
Operating conditions such as pressure, temperature and viscosity all affect the demands placed on a pump. Its settings therefore need to be adjusted to ensure optimum operation. With conventional progressive cavity pumps, however, this is not possible.
The HiCone’s smart adjustment system ensures that the rotor and stator can always be positioned optimally in relation to one another. When the pumping elements are precisely matched to the operating conditions, contact pressure between the two components is reduced, helping to minimise both wear and power consumption.
Thanks to its conical design and the ability to readjust the pumping elements, the HiCone provides durable, highly efficient pumping technology while reducing the cost of spare parts and maintenance.
The HiCone also runs more quietly and smoothly than conventional progressive cavity pumps while maintaining a consistent pumping capacity. With conventional pumps, performance can fluctuate as wear increases. Consistent pumping capacity is particularly important for ensuring that the liquid feeding system operates efficiently and delivers a well-prepared, homogeneous suspension to the system.
Uwe Ringen said:
“The HiCone puts us in a very good position. It pumps consistently – much more smoothly and evenly than conventional pumps of this type. Thanks to the modernisation of our system, we can respond flexibly to changing requirements.”
The farmers were so impressed with the HiCone’s performance that they also installed a progressive cavity pump on the external heat exchanger. Depending on the weather, it runs for up to six hours a day to maintain a constant digester temperature of 53°C.
The HiCone automatic control system allows Drewes and Ringen to make adjustments while the pump is running. Its smart automatic start-up function also keeps starting torque low, reducing the energy required when the pump starts.
Digesters at the AD plant
This offers another important advantage: the power required to start a pump is generally a key factor in determining the size of its drive motor and, consequently, the dimensions of the power electronics and safety components. With the HiCone automatic control system, these components can be specified at a smaller size, significantly reducing costs.
As Uwe Ringen explained:
“We needed technology that was durable and could be flexibly adapted to our operating conditions. With the HiCone, we have a highly efficient solution that we can adjust and readjust to suit our requirements.”
Learn more about the HiCone.