A cost effective, energy saving boosted evaporation process for alumina refineries

Hongyu Zhang, Hui Tong Chua, E. Boom, D. Cochrane

Research output: Chapter in Book/Conference paperConference paper

Abstract

Evaporation process is a significant section in the alumina production by the Bayer Process. It consumes a large amount of thermal energy and helps to manage water balance. We introduce a novel flash boosted evaporation process that can reduce live steam consumption for evaporation purposes, by using the available waste flash vapour from the last stage of the evaporation unit. The process can economise on the consumption of live steam, as waste flash vapour injection into the patent pending Flash Boosted Thermal-Vapour Compression Multi-Effect Evaporation (FB-TVC-MEE) process is able to minimise the motive steam usage of the Thermal-Vapour Compressor (TVC). We compare this novel FB-TVC-MEE process with the conventional Thermal-Vapour Compression Multi-Effect Evaporation (TVC-MEE) process and the current Multi-Stage Flash (MSF) process in terms of the amount of saved live steam, Gain Output Ratio (GOR), and specific pumping power consumption.
Our result shows that 82% of the current live steam consumption can be saved, with our process having the ability to exploit all the available flashed vapour for the evaporation of feed spent liquor. The Gain Output Ratio of our design is 468% better than the current MSF system and 98% better than the conventional TVC-MEE process. With regards to the pumping power consumption, the FB-TVC-MEE process shows a 5% increase as compared to the TVC-MEE process. Importantly, at a risk discount rate of 10%, the FB-TVC-MEE process has been shown to cost the least (both capex and opex considered), auguring 57% net present cost savings compared to the standard MSF technology that consumes 40 ton per hour of live steam with a baseline capex of $30 mil.
Original languageEnglish
Title of host publicationAlumina2018
Subtitle of host publicationThe 11th AQW International Conference: Efficiency for the future
Place of PublicationAustralia
PublisherAQW
Pages90-98
Number of pages9
ISBN (Electronic)9780646991641
Publication statusPublished - 2018
EventAlumina 2018: 11th AQW International Conference - Efficiency for the future - Gladstone, Australia
Duration: 9 Sep 201814 Sep 2018
http://www.alumina2018.com/

Conference

ConferenceAlumina 2018
Abbreviated titleAlumina2019
CountryAustralia
CityGladstone
Period9/09/1814/09/18
OtherThe Alumina Quality Workshop began in 1988 as a forum to bring the world’s alumina producers and their customers together to exchange ideas and information around a common goal of improved product quality. The symposia have been held in Australia at an interval of three years. Over time, the workshop has evolved into a major international symposium, incorporating all aspects of the production of alumina from bauxite. In recognition of this evolution we have rebranded the conference name Alumina 2018. The conference offers a unique opportunity to hear about the latest developments in alumina production and to network with other alumina producers, researchers and suppliers. The conference theme Efficiency for the Future reflects the current industry focus on cost reduction, optimisation of raw materials & energy use and the adoption of new technology. This continual drive for improved efficiency will ultimately result in a sustained and thriving alumina industry for the future.
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