Pushing the efficiency envelope

13 April, 2017

The cement industry is enormously energy intensive. Aside from the very high heat required to create lime, a significant proportion is expended on compressed air, both to supply the oxygen for the kilns and for bulk transportation by pneumatic conveying.

The pneumatic conveying process, the transportation of powdered or granulated materials through enclosed pipes, is used in a wide range of industries and allows plant managers to precisely control the conditions in which the material is transported including the temperature, humidity and cleanliness. With an ever increasing focus on product quality management and health & safety requirements, it should not come as a surprise that the already widespread use of pneumatic conveying is expected to grow.

As with other energy-intensive industrial processes, how can such growth be achieved in a sustainable way? This is an obstacle that many in industry are yet to overcome ahead of new regulations set out by the EC. The EC Ecodesign Lot 31 project is reviewing new energy reduction standards for low pressure compressors of the type used in pneumatic conveying.

The need for innovation

With many businesses still using outdated technology, innovation is needed to help companies reduce their energy spend in this important area.

Although some plants use mechanical conveying, many employ compressed air systems as they allow products to be conveyed easily and quickly. These use a relatively simple and small-diameter pipeline, have less moving parts and a smaller footprint. While mechanical systems work well in straight runs, a direction change or ‘bend’ can require its own motor and drive, unlike pneumatic conveying pipes.

The most common compressor technology used for pneumatic conveying is the lobe or ‘roots’ compressor, the modern twisted lobe version of which dates all the way back to the 1870s. In fact, most compressors have barely changed for a very long time and even the more modern screw compressor, commonly used at higher pressures, dates back to 1935. Yet compressors account for 10% of Europe’s industrial electricity use and over 40% in some plants. That equates to over 10TWh of electricity every year and over 4.3 million tonnes of CO2.

Some compressors are often inefficient because the rotating parts do not seal well, which consequently allows for air to leak during the compression process. And, despite improvements made to minimise the loss, the fundamental geometry of the existing compressors is ultimately a limiting factor.

Blade compressor technology

An effective alternative is blade compressor technology, something we believe to be the first substantially new air-end design in more than 80 years. A circular mechanism replaces the old rotary technology, compressing air – or gas – in front and inducing air behind in continuous motion, minimising waste.