Alcoa’s Anglesea power station (APS) is located about 120 km southwest of Melbourne, Australia and is a key supplier of power to the Point Henry aluminum smelter.
Hatch conducted an FEL 3 feasibility study including basic engineering for the retrofit and integration of a flue-gas desulfurization process within the power station. The purpose was to reduce stack SO2 emissions, thereby reducing ground-level concentrations in surroundings areas. Building on an earlier Hatch study, the technology selected was a limestone slurry forced oxidation (LSFO) process.
The proven engineering solution reduces sulfur emissions by treating 100% of the exhaust flue gases with slurried limestone reagent in a scrubber with high-efficiency SO2 removal. The sulfur in the gas reacts with calcium carbonate (limestone) to chemically remove SO2 with the resulting by-product converted to a stabilized gypsum. The limestone reagent is sourced locally and the gypsum can be used in both industrial and agricultural markets within the region.
The feasibility study included site studies, process and design engineering, equipment specifications, estimating and implementation planning, consulting with environmental agencies and affected stakeholders, and services for securing all needed environmental approvals and permits for the project.
We addressed all design, supply, installation and commissioning of the following components:
- LSFO FGD process design; energy, mass and materials balances; process support for limestone reactivity assessment
- Limestone receiving, handling, grinding and storage facilities
- Gas path ductwork modifications, new dampers and flue-gas booster fans
- Absorber island complete with recirculation pumping system and forced oxidation system
- Primary and secondary gypsum dewatering, handling and storage facilities
- New chimney designed for wet flue gas
- HV/LV power and control system
- Plant-wide infrastructure and utilities
- Modifications to the existing plant facilities to integrate the new FGD system and related works.
An integrated team was established comprising client site personnel, local Hatch project managers and engineers with specialist support from Hatch offices in Canada, and in Newcastle and Wollongong, Australia.
The feasibility study was completed in less than 12 months and fully considered all of Alcoa’s key criteria including capital cost, operating expenses, energy efficiency, reliability, maintainability and utilization of raw materials and utilities.
Value-added outcomes of the project included:
- Strategic contracting strategy that achieved overall CAPEX savings and minimized construction risks
- Customized limestone receiving facility and vertical mill preparation equipment to match the local soft limestone
- Limestone reactivity specification and testing support
- Identified opportunity for flue-gas heat recovery to mitigate CO2 emissions and water requirements
- Gas path bypass system to improve reliability and flexibility of the power station
- Utilization of centrifuges for dewatering of gypsum to meet current and potential product quality requirements
- Integration of process equipment, structures, utilities and footprint to minimize overall costs.