Energy saving potential analysis of a short cycling industrial air compressor in a marine equipment manufacturing plant in Türkiye

Abstract

Compressed air systems are recognised as significant energy users and are characterised by their notably inefficient energy consumption. This ensures their significance and potential for decarbonisation through cleaner and more responsible energy consumption in manufacturing facilities, such as marine equipment manufacturing plants in the shipbuilding industry, in order to address the various economic and regulatory challenges related to energy use and climate change. In the relevant literature, there are numerous studies on various energy-saving measures for compressed air systems; however, none concentrates on the problem of short-cycling phenomena and associated energy-saving potential. In this study, using a novel and systematic energy audit methodology, a detailed energy audit of a rotary-type screw air compressor was conducted at a marine equipment manufacturing plant in Türkiye. The systematic energy audit methodology was based on the measurement of power consumption and the evaluation of various operation parameters to assess the existing performance of the compressor, including compressed air demand, compressed air production, cycle speed, air tank volume, specific capacity, and duty cycle. The audit results revealed that the air compressor was short cycling, resulting in excessive energy consumption. Comprehensive technical and economic assessments were conducted to determine the root cause of the compressor's short cycling and to identify energy-saving potentials. It was determined that the compressor was oversized relative to the plant's compressed air demand patterns, while the air tank was inadequately sized, causing the compressor to engage in short cycling. To replace the existing short-cycling compressor, a scenario analysis revealed that the deployment of an optimised system consisting of a fixed-speed baseload compressor and a variable-speed trim compressor can reduce the plant's energy consumption for the compressed air system by a significant 73%. This results in annual energy savings of 74,160 kWh, annual cost savings of €9.373,8, and an annual reduction of approximately 49,9 tonnes of carbon emissions. This application requires an initial investment of €24.280 and is anticipated to redeem itself in 2,2 years. Moreover, it is anticipated to generate a net present value of €147.602 over its 20-year lifespan.