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Recovering heat – and profitability

13 February 2014

For businesses there are a number of avenues to explore when it comes to saving energy. One energy saving opportunity for many compressed air users is waste heat recovery, explains Mark Whitmore, general manager at BOGE Compressors


Rising electricity prices over recent years have added yet another challenge to those striving to maintain profitability.  Running a lean business has rarely been so difficult but one technology is developing fast to help recoup the cost of energy – heat recovery.


This technology is now being applied on a large scale.  For example, an innovative scheme in the UK will provide warmth for local homes by channelling waste heat from London Underground tunnels. The London Underground system generates large amounts of heat and that is to be captured from a Northern Line vent and piped into the heat network.  It is hoped that the project will reduce bills and lower carbon emissions, as well as drive innovation, jobs and growth in what looks to be a burgeoning sector. 


For businesses there are a number of avenues to explore. One option that provides an energy saving opportunity for many compressed air users is waste heat recovery. 


Because almost the entire energy consumption from the supply net of a standard compressor is converted into heat there is a correspondingly high degree of energy available for heat recovery.  Take for example an oil lubricated screw compressor: Up to 94% of the electrical energy input to this equipment is available for heat recovery. 


This waste heat generated by the compressor can be re-directed into heating spaces, just as it is in the London Underground initiative. This is especially efficient in plants where the compressor is within the vicinity of the area being heated, for example in a workshop where the compressor is stationed, or by the use of ducting where the compressor is in a more remote location. 


It is also possible to extract waste heat from the compressor to heat water for use in central heating or boiler systems, industrial cleaning processes, plating, operations, heat pumps, laundries, or any other application where hot water is required.


For businesses that are considering investment in heat recovery, a compressor specialist can help calculate the potential energy and cost savings to highlight the possible payback in terms of the immediate reductions in fuel, oil and gas costs.  The benefits are typically striking; for example, the BOGE Duotherm heat recovery system can recover up to 94% of the input energy used in compression in the form of heat. 


Before investing in heat recovery, the user can calculate the potential energy and cost savings of implementing the process by assessing the heat or hot water demand in areas where practical adjacent to the compressor installation. This assessment can then be compared to the average operating hours of the existing compressed air system, which will highlight the possible payback in terms of the immediate reductions in fuel, oil and gas costs.


With energy consumption typically the biggest target for engineering operators when looking to make saving and improve efficiency, designers and engineers have invested much time and effort in recent years into developing energy efficient compressed air solutions. This is a core mission at BOGE where the growing popularity of heat recovery has led to the recent extension of the Duotherm heat recovery product range, now available as an external, stand-alone model. As well as recovering up to 94% of the input energy used in compression in the form of heat the Duotherm heat recovery system is compact, requiring only a minimum space requirement, and connects into the oil circuit of the compressor with no external energy needed for operation.


Re-directing the heat generated by a compressor for heating spaces or heating water are options which can assist the end user in significantly reducing their associated energy bills and optimise their compressor use.  So, it’s well worth considering heat recovery as a means of recovering not only energy but profitability.


 
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