Waste-heat utilization – The sustainable technologies to minimize energy consumption in Bangladesh textile sector

Abstract

Waste-heat utilization holds great potential for cleaner production by improving energy efficiency, reducing energy usage and enhancing engineering functionality of an industry. Utilization of waste-heat is highly neglected in textile industries of the developing countries. This study quantified the energy and cost saving potential of waste-heat utilization in textile industries with several case studies. It focused on the common waste-heat sources and readily implementable technologies considering both technical and economic aspects. A waste-heat recovery boiler with a capacity of 2.70 t/h ran by hot exhaust from onsite electricity generators was estimated to save annually 15,094 MWh of energy and energy cost of USD 141,280. Installing economizer reduced 4.9% of boiler fuel consumption. Approximately 10% of energy used in stenter-setting machines was saved by installing a heat-exchanger that extracted waste-heat of stenter exhaust to preheat fresh air supplied to stenter operations. A counter-flow heat-exchanger was set up for utilizing waste-heat of dyed waste water. The yearly energy saving potential was 5716 MWh along with minimizing annual energy cost of USD 47,100. A proper stem-condensate recovery system reduced water loss and 10.50% of energy saving was achieved for steam production.