The 50% energy savings are possible. Following simple measures, the rotating speed of a vacuum pump can often be reduced by 30% (x 0.7) and thus the power consumption by 50% (as 0.7 x 0.7 = 0.49). Since the 1990s, we have often reduced the specific consumption and saved 50% of energy by replacing liquid ring pumps, often 25 years old, with new liquid ring pumps. This energy saving is more relevant today than ever before.
VAKUO manufactures two types of liquid ring vacuum pumps – radial distribution with cones or axial distribution with port plates as well as radial fans and Roots blowers.
Simple questions like “how much vacuum do we really need, and when?” or a measurement of the pump actual capacity lead to good practices and sustainable energy savings.
10 important topics for a better reliability and lower operating costs
1. When to replace a vacuum pump?
We recommend testing the performances of each pump regularly, ideally every year. We offer audits including on-site performance tests and endoscopies. Measurement and analysis of the results are the first essential step towards optimization.
2. Repair or replacement through a new or swap pump?
As important as the question if the pump is in good conditions, We have to ask and check if it is the right pump (adequate size) for your actual effective needs? Each 100 kW pump can save or waste up to 30 kW.
The extra costs or potential saving are high: 30 kW x 12.5 ct/kWh x 8,000 h/a = 30,000 €/year. 30,000 € is approximately the price for a new pump of this size, the price for repairing or replacing a pump is negligible compared to the annual energy savings.
3. Why does the efficiency of the pumps decrease over time?
Wear, due to corrosion or abrasion affect the critical clearances and result in lower flow. Also the deposition of fibers, scale or limestone clogs the inner channels, resulting in pressure drops and increased electrical consumption. A wrong response would be to increase the rotating speed to compensate for the loss of capacity: high tip speed means poor efficiency, and also more wear and more maintenance.
4. What is the expected efficiency of a pump?
1 kW per m³/min is our benchmark, it is the specific consumption for properly sized pumps in good condition. Liquid ring vacuum pumps taking advantage of the condensation effect, can easily reach this efficiency.
If the system was properly analysed and designed, liquid ring pumps, turbo blowers, high speed fans, roots blowers… will all reach the same efficiency – with various advantages and disadvantages.
5. Central system or dedicated pumps?
A system with dedicated pumps for each area is more adaptable and efficient and avoids expansion, which can cause a loss of performance.
6. With pre-separator?
Vacuum pumps (compressors) are designed for pumping air or steam and not for pumping liquids. Liquid ring pumps are robust but very inefficient when handling liquid: the energy consumption and the wear increase. A pre-separator improves efficiency and maintenance intervals.
7. Energy saving with cooler/colder water?
Yes, but not directly. Using a colder water, only increase the suction power of the pump. This increase in flow makes it possible to reduce the speed. We save energy by reducing the speed, i.e. by replacing the small motor pulley or installing a frequency converter. Cold water alone is not enough.
8. Port plates (axial) or cones (radial)?
Both designs have pros and contras – VAKUO offers both: conical pumps are more robust and more efficient when we take advantage of larger ports to recycle more water, get a lower ring temperature and a better efficiency.
Flat sided pumps (with port plates) are more versatile and adapt better to different vacuum levels. VAKUO has also launched the CNL Series combining conical design (larger ports) with the plate valves (adapting to the vacuum level and saving energy) like in the flat-sided pumps.
9. Are liquid-ring pumps capable of operating at variable speed?
Yes, especially liquid ring pumps benefit from the above-mentioned lever. The suction flow is proportional to the rotating speed, while the absorbed power increases (or decreases) exponentially. We can achieve high energy savings by adapting the suction flow (rotating speed).
10. What is the next step?
Call us now. Every day VAKUO analyses vacuum systems in the paper industry. By combining our experiences and knowledge, we will optimize your existing vacuum system.
50% energy saving using your existing systems with liquid ring pumps