Pond Water Heating System For Cameco Corporation McArthur River Project In Saskatchewan

PROJECT OVERVIEW

Case study - Sistema de Calentamiento de Agua de Laguna (CAMECO in Spanish) 

In early 1997, Inproheat supplied a 6 MM BTU/hr pond water heating system for Cameco McArthur River project in northern Saskatchewan. The McArthur project is one of the newest uranium mines located in a remote site approximately 500 kilometers north of Saskatoon. The mine was developed in late 1998. Two deep underground shafts will provide access to the ore body. Mining will be done by remote controlled machines to minimize worker exposure to the high grade ore. The shafts are subject to inflow of groundwater, which has to be pumped to the surface and stored in several large plastic lined ponds to prevent seepage into the underlying soil and hydrological regimes. Before the water is pumped out and discharged to the river, it has to be chemically treated and filtered. Since the ponds are located outside, and winter temperatures dropping below minus 40º C (-40º F), a thick layer of ice is formed on the surface. The ice can be as thick as 8 feet, reaching almost to the pond bottom. This creates a two-fold problem. Firstly, the ice formation reduces the pond capacity, and secondly, the ice cap moves when the water is pumped into or out of the pond. In the process, ice can tear the plastic liner, leading to the contamination of the surrounding soil and water system.

Pond Water Heating CAMECO-05

THE CHALLENGE

To reduce ice formation and minimize the potential loss of water containment, Cameco identified a need for an energy efficient heating system capable of handling up to 1,000 USGPM of pond water containing a high TDS which could very easily form a scale in a traditional heat exchanger system.

  • The system had to be able to handle widely varying flows.
  • The requirement for high efficiency was dictated not only by the economics but also by the logistics of trucking propane and fuel oil for several hundred kilometers and storing it at a remote location.

The automatic heater operation and lack of boiler engineer on staff also had to be taken into consideration.

THE SOLUTION

Inproheat designed and manufactured a 6 MM BTU/hr SubCom® submerged combustion system. The unit was skid-mounted prepackaged and prewired including the heating tank, submerged combustion burner, combustion air blower, propane fuel train, and control panel. The fabricated steel vent stack was shipped in two sections. Cameco designed and supplied their own water supply valves and piping, discharge pump box, pump, and fabricated steel platform. The pump box was located below the platform on which the Inproheat heating system was placed to enable gravity discharge into the pump box. Manual inlet valves were used to control the water flow into the heater, while an overflow weir controls the level built in the SubCom® tank. To attenuate the momentum of water inlet velocity at 1,000 USGPM flow, an internal perforated flow distributor was also incorporated into the inlet system. Cameco providedthe pump box level control system. The SubCom® burner fuel train was connected to a 15 psig propane supply. The unit is located in a water treatment building and operates without operator intervention.

THE RESULT

Inproheat commissioned and started up the system in March 1997. A number of combustion tests were conducted. The water discharge temperature was set at 12º C (54º F), with stack temperature between 11 and 13º C (52 and 55º F). The resulting overall system efficiency was calculated at 98.5% of the propane higher heating value, compared to a typical maximum 82% efficiency of other heating methods.