(EECR-72)Identification and classification of waste heat streams and their exergy component review of enabling technologies on an integrated steelworks

摘要

With the steel industry being under pressureto reduce its carbon footprint and energy prices beingon the rise in recent years, improving energyefficiency is critical for an integrated steelworks.Waste heat recovery could undoubtedly play animportant role in this effort. Previous studies andbenchmarking between Tata Steel integrated sites inEurope have shown that the recovery potential ofsome of the high-grade waste heat sources (>500oC)has not been fully realised and numerous sources oflow- (<300oC) to medium-grade (<500oC) waste heatare usually neglected. In this study, the majority ofthese sources have been identified and the potentialsfor beneficial utilisation of waste heat have beendetermined. The quantification of heat losses aroundan integrated site has been carried out using asimple methodology and established thermodynamicformulas, for gaseous, liquid and solid sources. Also,the Exergy of Heat has been introduced to provide ameasure of the “quality” of waste heat.Results showed that heat losses from coolingwater around an integrated steelworks can exceed4.5 GJ/tcs whereas waste heat from combustionstacks can exceed 1.5 GJ/tcs. The highlights in thearea of high-grade waste heat include coke heatlosses at 1.4 GJ/t coke and BF and BOF slag whereheat losses account for 1.4 GJ/t and 2.0 GJ/t of slagrespectively. Exergy values from virtually all solidsources reveal the high potential for heat recoveryvia a thermodynamic cycle. The potentials for novelenergy recovery techniques, heat pumps andinnovative thermal cycles (e.g. Kalina~R cycle) havebeen studied and could be an integral part in meetingthe targets of improving energy efficiency andreducing the carbon footprint of the steel industry.