Energy Recovery (ER) systems are specifically designed to transfer the energy recovered from air compressors to the customers' process. A properly designed heat recovery unit can recover anywhere from 50-94% of available thermal energy (as low-grade heat) to heat air or water (up to 90?C or 140?F). Pre-heated water can be used in the application process to reduce the use of traditional energy sources reducing the amount of CO2 emissions.

Compressed air is one of the most important utilities for industry. It is also one of the largest consumers of energy. Therefore, any savings made in compressed air systems have a significant impact on costs and on the environment. While compressed air systems in general account for about 10% of total industrial electricity consumption, this can amount to as much as 40% of the electricity bill for certain plants.

The way to achieve the highest energy savings is to recover wasted energy through radiation losses by the use of heat recovery systems. As much as 94% of the electrical energy used by an industrial air compressor is converted into heat and loss through radiation in the compression process. The remaining 6% is converted into compressed air heat losses. In view of this, Atlas Copco has been innovating in energy-efficient compressed air solutions for many years.

Hot water recovered from the compressed air system can be used for many process applications. Hot water and steam are used in many dairy processes. Steam is commonly used for pasteurization, scalding, cleaning and sterilizing cooking vessels, drying products, etc. In larger dairies, huge amounts of hot water and steam are required in continuous processes. Here, the hot water energy recovery system of the compressor can provide substantial energy savings.

The chemical industry and refineries are major users of steam. Some applications are: thermal steam crackers, which require highly superheated steam at typically 40 bar; re-boilers and stripping employ superheated medium pressure steam at typically 10 bar; and heat tracing and other applications require superheated low pressure steam at typically 2 bar. In some processes, a great deal of hot water is recovered after the steam condenses. Hot water from compressors is used as make-up water to supplement the losses.

Large amounts of steam are used in the pharmaceutical industry and in manufacturing processes. Fermentation temperature control, drying and sterilization processes are part of the daily routine of the pharmaceutical industry. The CIP (Clean in Place) cleaning method, SIP (Sterilization in Place), direct contact sterilisation in bioreactors and fermenters, and steam barriers against bacteria are commonly employed in these manufacturing units. The heat energy recovered from the Atlas Copco air compressor contributes to a higher bottom line.

Colouring of fabric makes use of considerable volumes of hot water at 80? to 90?C. Energy Recovery systems of Atlas Copco's compressors can directly offer the hot water to the process. For yarn and fibre treatment, steam is used for heat-setting manmade fibres to achieve dimensional stability, increased volume, and wrinkle and temperature resistance. Significant volumes of compressed air are used in the wood pulp and paper industry.

Vast amounts of steam are also used in the industrial processes. Typical applications are bleaching, digesters, pulp machines and black liquor evaporators. Steam is used for humidification since it is clean and inherently sterile. Clean room humidification in electronics assembly, chip manufacture and in pharmaceutical industry is common practice. As this steam is used as a utility, continuous replenishment water is required. Hot water from the air compressor can pre-heat the replenishment water, and consequently, reduce the energy consumption of the steam boiler.

Highly superheated steam (typically 40 bar) is used for motive applications such as steam turbines. Turbines are used as prime movers for captive power generation and for several machines. Preheated boiler feed water reduces fuel consumption in boilers resulting in significant savings.

Committed to sustainable productivity' is Atlas Copco's brand promise. This is a promise to ensure reliable, lasting results with a responsible use of resources; human, natural and capital. Increasing productivity is the foundation for all of Atlas Copco's business activities.

(Atlas Copco is an industrial group with world-leading positions in compressors, construction and mining equipment, power tools and assembly systems. The Group delivers sustainable solutions for increased customer productivity through innovative products and services. Contact: Atlas Copco Compressor Sales, Pune. Tel: 020-39852302. Fax: 91-20-39857009. Email: keerti.lele@in.atlascopco.com)