Techno-economic analysis of ECF bleaching and TCF bleaching for a bleached eucalyptus kraft pulp mill

Abstract

An early stage techno-economic analysis was performed to compare a traditional elemental chlorine free (ECF) sequence (O O D0 [EOP] D1 P) with the proposed totally chlorine free (TCF) sequence (O O A [ZEO]1 [ZEO]2 P)] for a bleached eucalyptus kraft pulp mill. Similar operating costs (ECF = US$465/a.d. metric ton; TCF = US$468/a.d. metric ton) and similar internal rate of return (ECF = 16.5%; TCF = 16.4%) were obtained. Although the TCF case has lower revenue with surplus steam, savings with chemicals (e.g., sodium chlorate and methanol) pays for the higher consumption of electricity. Probabilistic analyses were also performed to evaluate the financial risks associated with the variability of chemical costs and electricity price. Probabilistic analyses have shown that the price volatility of sodium hydroxide and sodium chlorate have a significant impact on the probability distribution of internal rate of return (IRR). Despite its promising potential, the new TCF sequence has only been tested in laboratory scale and further scaleup has to be performed to validate the technology. However, the techno-economic economic analysis shows that the proposed TCF technology has promising potential for future industrial application.