This week (1-5 October) saw the Intergovernmental Panel on Climate Change (IPCC) meeting in Incheon, Republic of Korea, to agree on a plan of action to limit climate change from rising by more than 1.5C this century. In light of this, Mattei is once again calling on industry to assess how air compressor specification can make a difference to greenhouse gas emissions. Andy Jones, managing director at Mattei, comments.
“The industrial sector accounts for more than 50 per cent of global electricity consumption (6673TWh), and of this, up to 20 per cent (1335 TWh) is due to air compression and delivery to its final uses.
“With this in mind, it’s clear that energy saving and energy recovery in industrial compressed air systems should be recognised as an important consideration in any plan to reduce greenhouse gas emissions and curb global temperature rises.
“Whilst most major compressor manufacturers have successfully reduced their specific energy over recent years, there is much more to compressor efficiency than the traditional specific energy calculated by the conventional life cycle cost calculation (LCC).
“Mattei has long argued that traditional discussions fail to take into account changes in efficiency across the lifespan of a compressor – therefore, a true Life Cycle Cost (LCC) cannot be reached. Relying on the standard life cycle cost calculation does not factor in fundamental design issues and long-term wear and tear. As a result, buyers are being misinformed on the true running costs of units, preventing accurate analysis of energy usage.
“Many are unaware that screw and vane compressors differ significantly in terms of lifetime efficiency. In the case of screw compressors, tests have shown that efficiency deteriorates from the beginning of operation, as roller bearings are subject to wear, contingent on speed and load. Although screw compressor manufacturers advise the substitution of all major rolling and thrust elements after a certain number of operational hours, any modification of the clearances is likely to have a significant impact on efficiency, as internal air leakage becomes highly likely.”
“By contrast, the efficiency of vane compressors can actually improve over an initial running-in period. With no roller and thrust bearings to experience wear within the unit, from the moment a rotary vane compressor is turned on the compression unit undergoes a polishing process. This also means that the manufacturing set clearances are constant throughout the lifetime of the compressor. The benefit of this is two-fold. First, there will never be any loss in volumetric efficiency over time, and second the compressor will never require an overhaul to substitute the worn bearings.
“With these fundamental engineering differences between vane and screw compressors in mind, along with the previously discussed wear issues, it is clear that the standard LCC cannot be relied upon as a true representation of lifetime energy efficiency.
“In the face of global warming, and the devastating consequences that could accompany significant climate change, it is vital that we recognise the reality of compressor efficiencies and the impact that this can have on reducing industrial emissions. By choosing a rotary vane compressor, such as those available from Mattei, industry professionals can increase the efficiency of their outfits, and potentially help save the planet in the process.”