Energy-efficient screw blowers

Paul Boughton
Atlas Copco's new energy-efficient technology for air blowing applications is the ZS screw blower. Screw technology on average is 30 percent more energy-efficient compared to lobe technology.

Atlas Copco says it is convinced that the lobe technology, widely used at present, no longer meets the needs of today’s low carbon economy. Industries and applications such as wastewater treatment, pneumatic conveying, power generation, food and beverage, pharmaceuticals, chemicals, pulp and paper, textiles, cement, and general manufacturing will highly benefit from energy savings through replacing the conventional lobe with the leading screw technology. The ZS screw blower will replace the company’s entire range of ‘Roots’ type rotary lobe blowers.
According to the United States Environmental Protection Agency (EPA), for example, '…approximately 56 billion kilowatt hours (kWh) is used for drinking water and wastewater services. Assuming an average mix of energy sources in the country, this equates to adding almost 45 million tons of greenhouse gases to the atmosphere. Just 10 per cent of energy savings in this sector could collectively save about $400 million annually'.
In a typical biological wastewater treatment plant, the aeration blower system accounts for up to 70 percent of the energy usage. Today the majority of these plants use less efficient lobe technology, a technology that has had little development since its introduction in the late 19th century. By reducing the energy usage of their aeration blower system, these plants will decrease their energy costs while operating in a more environmentally friendly manner.
Many industries use air blowers for their processes and will benefit from the energy efficiency of screw air blowers. Those that will have a major benefit are the municipal and industrial wastewater treatment plants, where air blowers typically represent up to 70 per cent of the total electricity costs. Here, millions of bacteria feed on organic waste, breaking it up into carbon dioxide, nitrogen gas and water. Because the bacteria need oxygen, large amounts of air are blown in the aeration tanks.
The performance of the new ZS screw blower was tested against a tri-lobe blower by the independent Technische Überwachungs-Verein (German Technical Monitoring Association, or TÜV), according to the international standard ISO 1217, edition4. It was proven that the ZS is 23,8 percent more energy-efficient than a tri-lobe blower at 0,5 bar(e)/7 psig, and 39,7 per cent at 0,9 bar(e)/13 psig. The world-class efficiency of the ZS is mainly attributed to the superior screw technology. Other important features that secure increased efficiency and reliability are the integrated gearbox, the oil system and the innovative design that integrates all individual components into a plug-and-run solution.
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