Thermo-economic analysis of low-grade heat driven multi-effect distillation based desalination processes

• Published in: Desalination Vol. 448; pp. 36 - 48
• Main Authors: Datsgerdi, Hamid Rezvani, Chua, Hui Tong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2018
• Subjects: Desalination; Multi effect distillation; Seawater; Thermo-economic; Waste heat; Waste heat; Multi effect distillation; Desalination; Thermo-economic; Seawater
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2018.09.018

We examine the economic viability of three multi-effect distillation (MED) based processes against the MED as a benchmark, when they are driven by low grade heat. We model and compare the Boosted MED (BMED), Flash Boosted MED (FBMED) and Distributed Boosted MED (DBMED) processes with the MED in terms of waste heat performance ratio, specific capex and opex. All three new configurations generate significantly higher productions than MED with higher capex and opex investment. We provide the corresponding cash-flow analyses using such financial metrics as the Net Present Value (NPV) and Internal Rate of Return (IRR). This study leads to the conclusion that the DBMED process is the superior scenario up to an interest rate of 12.5% at 65 °C heat source supply temperature which then drops to 8.4% at 90 °C heat source supply temperature. Also, the analysis shows for the high interest rates (above 8.4% at 90 °C), MED has higher NPV compared to other MED based processes. The distributed boosted multi-effect distillation (DBMED) powered with low grade heat resources has been compared against MED, Boosted MED (BMED) and Flash Boosted MED (FBMED) in both technical and economic aspects. [Display omitted] •The distributed multi-effect distillation process is the best process for waste heat.•At 65 °C heat source temperature, this process is superior up to 12.5% discount rate.•At 90 °C heat source temperature, this process is superior up to 8.4% discount rate.•Beyond these discount rates, conventional process with lower capex is more viable.