Vogelsang innovation improves efficiency of wastewater solids transfer
10 April 2006, News release from Vogelsang Ltd
A new patented innovation is now available in the UK. The dynamic injection system from Vogelsang, a leading manufacturer of rotary lobe pumps, improves the efficiency of wastewater solids transfer.
The new development allows more efficient pumping of solids such as in un-screened sewage. Following extensive research and development in Germany, and numerous projects managed by Vogelsang's American and German offices, Anglian Water is the first UK end-user to incorporate the system on a pump recently installed at Flag Fen in Peterborough. The system includes a new housing segment that has an angled entry, directing liquid and solid objects through the pump more efficiently. We describe how the innovative system works and outline the application of this new technology.
For over 75 years Vogelsang has been committed to developing innovative pumping, grinding, and spreading solutions. Through extensive research and development the Company has led the industry in the design and manufacturing of various developments including the HiFlo, the first pulsation-free positive displacement rotary lobe pump. Their latest innovation to arrive in the UK is the dynamic injection system which can be fitted to this range of pumps.
The system comprises a specially designed housing segment (see Figure 1) with an angled entry and extended surface which directs the flow of liquid and solid objects through the pump more efficiently without the need to alter lobe design.
In rotary lobe pumps without the dynamic injection system, large solids touch the lobe tips when passing the suction area. These particles become trapped inside the vortices, touching lobes repeatedly, resulting in accelerated wear at the lobe tips (see Figure 2).
The transfer efficiency is significantly increased because the new design overcomes the vortex effect by directing the flow into the centre of the suction side of the pump (see Figure 3). Solids are transferred into the lobe space without touching the lobe tips. This reduces wear but, because of increased fluid acceleration, the lobe spaces fill more readily leading to increased efficiency without any significant change to NPSHR.
The danger of cavitation occurring is minimised and the number of lobe sealing lines is increased. The dynamic injection system housing comes into contact with a lower fluid level resulting in a better seal between the upper lobe and the housing, also increasing efficiency.
Figure 4 shows test results from a rotary lobe pump with two chambers. 1-20 mm sand and water was pumped through both chambers. The results show lobes from the chamber with the dynamic injection system at the top, and below, lobes from the chamber without the new system. The excessive wear on the lower lobes can be clearly seen.
The whole life cost of a HiFlo rotary lobe pump in high solids applications fitted with the dynamic injection system is significantly lower than a pump with a standard housing. The slight increase in capital cost of around 3% is more than offset by extended pump life, typically 2.5 to 5 times that obtained from a standard housing. If increased efficiency is taken into account along with lower maintenance and downtime requirements and the reduced need for spare parts, the dynamic injection system is extremely cost effective.
All existing HiFlo pumps can be retrofitted with the new housing with no modifications. In-situ maintenance is straightforward; should it be necessary to change lobes this can be done in less than 30 minutes. HiFlo pumps can run dry for 30 minutes without causing any damage and, because the pump and motor can be vertically mounted, the footprint requirement can be as low as one third of that required by alternative suppliers. Vogelsang pumps are fabricated in Germany to project requirements and bespoke solutions are provided to meet specific site conditions.
Vogelsang's HiFlo rotary lobe pumps are used in municipal water and wastewater treatment, industrial and chemical industries, the food and beverage industry, mills and recycling facilities, and also in portable applications where temporary on-site requirements exist.
The use of the new dynamic injection system in these situations means that higher solids concentrations and larger particles can be pumped without affecting pump life or efficiency. Vogelsang engineers in the USA and Germany have successfully demonstrated the use of the new system on high and coarse solids applications, where wastewater containing grit and small stones is effectively pumped.
Specific sewage treatment applications include transfer of raw sewage, flotation slimes, digested sludge, scum, lime, carbide slurry, centrifuge and belt press feed, waste and return activated sludge, and polymer.
Based on the extensive experience gained overseas the new system has now been launched in the UK. The first municipal application for the pump is at Anglian Water's wastewater treatment plant at Flag Fen, near Peterborough.
A VX136 pump is installed to transfer un-screened primary sewage containing rags, other large solids and stones up to 40 mm in diameter, delivered by tanker from other Anglian Water sites to a sump. Because the HiFlo pump is self priming to 8 m and can run dry for 30 minutes without affecting performance, the addition of the new dynamic injection system means that raw sewage can be effectively pumped out of the sump for subsequent treatment on-site at Flag Fen.
The incorporation of an inverter variable speed drive increases efficiency still further and optimises the rate of raw sewage transfer, which can be set at 25 to 75 m3/h. The HiFlo positive displacement design operates pulsation-free across the whole flow range. To minimise footprint the pump is vertically mounted underneath its motor.
UK applications can now benefit from the exclusive dynamic injection system for Vogelsang HiFlo rotary lobe pumps. On high solids applications, HiFlo pumps will last longer and cost less overall due to increased pumping efficiency, less wear and reduced maintenance requirements.
About the Author
Toby Clarke is Managing Director at Vogelsang UK. He can be contacted at their office in Crewe on 01270 216600, or by email to email@example.com. Further details on the Company can be viewed at www.vogelsang.co.uk.
For further information please email Vogelsang Ltd