Fluid situation: sustainability in compressors
2017 February 13, 10:00 CEST
While Paris will be important in shaping environmental policy, the fluid machinery industry is more likely to be affected by a historical piece of legislation – the Montreal and Kyoto Protocols, Magnus Arvidsson, Business Engineer at SKF Group, explains.
The COP21 meeting in Paris was a seismic event that will have a huge effect on sustainability. Future legislation and guidelines are likely to be shaped by what was decided at the conference.
Rob Jenkinson, director of corporate sustainability at SKF, says the agreement reached in Paris must now lead to a raft of sensible and challenging legislation – introducing the practical measures that will restrict future temperature rises to less than 2 degrees C.
However, the ‘Paris effect’ will not be felt quite yet. And, as far as the use of refrigerant compressors is concerned, there is a far more significant piece of legislation shaping the industry: the Montreal Protocol. It came into effect way back in 1989 – the same year the Berlin Wall came down – with the intention of reversing damage to the ozone layer by phasing out HFC and HCFC refrigerants.
Some of the phase-outs agreed in Montreal – and in subsequent follow-up meetings – are now coming into effect. The refrigerant R134A, for example, will be completely banned in different regions and industries from next year, meaning that alternatives must be found: one potential replacement, a refrigerant known as R-1234yf, is currently being considered.
Those who have not previously prepared for this legislation are now under pressure from a ticking deadline. The rules will affect all use of compressors for refrigeration – from air conditioning units for cars to hospital cooling systems.
In parallel with this, air conditioning systems will be expected to run with greater energy efficiency – and this is also being addressed.
One solution that SKF has developed for AC centrifugal compressors is to make them oil-free. However, using magnetic systems banishes the need for oil – and raise efficiencies by up to 10%.
The main driver for this was a leading HVAC OEM in the US, which was seeking a reduction of energy consumption and efficiency increase for its centrifugal compressors. SKF helped it to meet this goal by supplying magnetic bearings, as well as the motor and control unit.
This OEM is a good example of an industry leader that pushes the environmental agenda forwards through its desire for efficiency gains. The company has recently extended its line of magnetic bearing centrifugal chillers – the YMC2 range – to handle 1,000 tonnes of cooling (3,500kW).
An alternative way of banishing oil is to use the refrigerant itself as the lubricant, which is possible by using SKF Pure refrigerant lubricated bearings ‘Hermetic’ compressors, used in air conditioning systems for hospitals or other large facilities, can be run in this way. The refrigerant then does its normal job – as well as cooling and lubricating the bearings.
Total cost of ownership (TCO) is an important concept that is still not fully understood – though the advent of higher-priced energy is certainly helping to focus people’s minds.
Variable speed drives (VSDs) have made a huge contribution to energy efficiency across industry – including fluid machinery. By driving the motor according to process need, the user can save up to 30% on energy costs. That’s a huge chunk – bearing in mind that energy accounts for 80% of the total cost of a compressor over its lifetime.
There is one small disadvantage of using a VSD: the electrical output of the drive can cause arcing, which can quickly destroy the bearing. The answer is to upgrade the system, such as by fitting insulating bearings that withstand arcing.
Permanent magnet motors (PMMs) can also have a huge effect on energy efficiency, in a diversity of industries. The wastewater treatment industry, for instance, uses blowers to aerate the water. This helps bacteria to break down organic waste more effectively. One French treatment plant had been using four traditional ‘Roots’ blowers for this purpose – which accounted for around half of the plant’s total energy consumption.
The plant replaced its four 80kW blowers with two 160kW aeration blowers based on a PMM, active magnetic bearings, SKF control system and VSD. As well as reducing noise, the new system cut energy use by 500,000kWh – as well as saving 375 tonnes of CO2 emissions and 54,000 euros. Payback time was just one year.
The technology that underpins the aeration blower – SKF’s high-speed PMM – is from its ‘BeyondZero’ portfolio of products, which can impart real sustainable benefits. Others that are relevant to this sector are the refrigeration-lubricated bearings and high-speed oil-lubricated bearings.
These are just some practical measures that are helping to improve the sustainability of compressors and other fluid machinery – helping customers meet or even exceed existing environmental legislation.
At this moment, at least as far as compressors are concerned, the Montreal Protocol is having the greatest effect in determining sustainability priorities. But we can be sure of one thing: future legislation – enacted in the wake of COP21 in Paris – will not take anywhere near as long to come to fruition.
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SKF is a leading global supplier of bearings, seals, mechatronics, lubrication systems, and services which include technical support, maintenance and reliability services, engineering consulting and training. SKF is represented in more than 130 countries and has around 17,000 distributor locations worldwide. Annual sales in 2015 were SEK 75 997 million and the number of employees was 46 635. www.skf.com
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