Hatch was retained by Skye Nickel Resources and Compañía Guatemalteca de Níquel (now HudBay Minerals) to prepare a feasibility study for a new 150-MW coal/petcoke-fired captive power plant to serve the Fenix ferronickel processing facility in Guatemala.

The project scope included refurbishment of a nominal 60-MW HFO-fired (heavy fuel oil-fired) boiler and steam turbine generator. The power supply is required to meet the average and peak power demand of the process plant, mine and housing complex. Dedicated power generation options for on-site or off-site power production were considered. A variety of power production technologies and configurations were reviewed to provide reliability of power availability for the
process plant. Technologies considered included reciprocating engines, coal/petcoke fuelled steam generation facilities and gas turbines.

The new power plant will consist of:

• A new 150-MW solid fuel CFB (circulating fluid-bed) boiler
• A new 90-MW STG (steam turbine generator)
• The refurbished, existing 60-MW nominal STG

Compañía Guatemalteca de Níquel also considered electrical power supply through a five-year Power Purchase
Agreement (PPA). Electrical power will be supplied via a new 150-km long, 230-kV transmission line; after the ferronickel plant is operating, a coal/petcoke fired power plant may be constructed on site or off-site.

Among a number of options considered, the optimal boiler-turbine configuration for on-site power production was found to include a full-rated (150-MW) boiler supplying the existing 60-MW turbine and a new 90-MW unit.

In addition to the full-rated CFB boiler, the new power plant will include the following features:

• Single-casing turbine design for maximum robustness in supplying industrial and smelting furnace load
• Steam-bypass valving on the larger turbine unit to accommodate severe furnace load reductions
• SPLC compensated furnace load to limit maximum furnace power demand and associated power plant rating. SPLC is a state-of-the-art smelting furnace compensation technology
• Closed-circuit condenser cooling water system with cooling tower rated for full heat rejection by the entire power plant

Scope of Services
Hatch’s scope of services included:

• A technical and economic feasibility study for a new captive power plant and possible grid interconnection
• Specifications for major equipment
• Development of design criteria for the power plant
• Development of basic engineering (FEL 3)
• Capital and operating cost estimates

Project Highlights
The project included Circulating Fluidized Bed (CFB) Boiler Technology. The advantage of a CFB boiler is its ability to burn a variety of solid fuels such as high-sulphur coal, or petcoke, using limestone to comply with environmental emissions. Another benefit is the formation of lower levels of nitrogen oxides.