50% energy savings are possible
With simple improvements and relatively easy modifications, the suction capacity of a vacuum pump or system can be increased by 30%, thus the rotating speed of a vacuum pump can often be reduced by 30% (x0.7) and thus the power consumption (as 0.7×0.7 = 0.49) will be reduced by 50%. Since the 1990s, we have often reduced the specific consumption and saved 50% of energy by replacing old liquid ring vacuum pumps through new liquid ring pumps. This energy saving is more relevant today than ever before.
VAKUO assists the papermakers in optimizing their existing vacuum systems
We have 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.
VAKUO manufacture both types of liquid ring vacuum pumps: radial distribution with cones or axial distribution with port plates, as well as radial fans and Roots blowers. Vacuum system supplier and vacuum pump manufacturer, VAKUO assists the papermakers in optimizing their existing vacuum systems. Simple questions like “how much vacuum do we really need, and when?” or a test of the actual pump capacity lead to good practices and sustainable energy savings. As an introduction, we have selected 10 frequently asked questions.
1. When to replace a vacuum pump?
Measurement and analysis of the results are the first essential step towards optimization. We recommend to test the performances of each pump regularly, ideally every year. We offer audits including on-site performance tests during a shut-down and endoscopies.
2. Repair or replacement through a new- or swap-pump?
Is the pump in good/bad conditions? But also: is it the right pump (adequate size) for your actual effective needs? Each 100 kW pump can save or waste up to 30KW; the extra costs or potential saving are high: 30 kW x 12.5 ct/kWh x 8000 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, affects the critical clearances and results 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, high power absorbed 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, we only increase the suction power of the pump, as we increase the suction capacity. 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.
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 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