Cost Effective Greenhouse Gas Reductions in the Steel Industry from an Organic Rankine Cycle

摘要

Large quantities of low grade heat (LGH) are generated within many process industries,rnand the recovery of LGH is a potentially significant means of improving processrnefficiency, but it is often difficult to find an appropriate internal heat load. Onernalternative is to use appropriate technologies to convert the low grade heat to electricityrnfor use on site. This paper describes the environmental and techno-economic evaluationrnof a case study examining the potential application of an Organic Rankine Cycle (ORC)rnto generate electricity from LGH from the stacks of a coke oven used in steelrnproduction. 21 MW of LGH was available for recovery at the plant and resourcernaccounting and lifecycle analysis methods were used to evaluate the environmental andrneconomic benefits of the operation of an ORC. The results showed that between 1 andrn3% of the CO_2 emitted directly through the production of coke would be offset byrninstallation of an ORC, with lifecycle environmental impacts of coke productionrnreduced by less than 1 %, although this was sufficient to offset over 10,000 t CO_2rnannually. However, the amount of electricity generated was sufficient to replace allrncurrently imported electricity and economic analysis indicated a relatively attractiverndiscounted payback period of between 3 and 6 years, suggesting this may be arncommercially viable option, which could present a relatively cost effective method ofrnachieving greenhouse gas savings in the process industries.