Environmental boost saves energy, water, cuts CO2.
Thermal-efficient technology for heavy oil extraction could transform oil sands operations.
A project involving the CanmetENERGY Ottawa Research Centre and Canada’s Oil Sands Innovation Alliance (COSIA) is developing a high-pressure, oxygen-fired direct contact steam generation (DCSG) technology that’s intended to replace conventional steam production.
“The innovative technology will not only significantly reduce fresh water consumption but also decrease greenhouse gas emissions (GHG) as well as water and air pollution,” says Bruce Clements, a combustion technologies research scientist with CanmetENERGY in Ottawa.
With DCSG technology, a fuel is combusted with pure oxygen at high pressure. Wastewater contaminated with hydrocarbons and dissolved or suspended solids, such as the type produced from steam-assisted gravity drainage (SAGD) and present in tailings ponds, can be used with this system to create the final product – a flue gas stream consisting mainly of steam at 90% and carbon dioxide (CO2) at 10%. Trials have shown the process to have a thermal efficiency of nearly 100%.
This new method of producing steam for heavy oil extraction pumps the flue gas stream underground, at which point CO2 is sequestered, saving energy and diverting emissions.
Clements notes firing has been successful so far and will pave the way for the construction of a DCSG pilot plant capable of going up to 100 bar in a few years.
The pilot plant will use process water with high solids and hydrocarbon contamination directly fired with natural gas. Clements expects that other waste fuels, such as petroleum coke and asphaltene, could eventually be combusted, and a demonstration DCSG plant might eventually be feasible.
In addition to the environmental benefits of DCSG, Clements notes the process will produce an inert, vitreous slag, a by-product potentially suitable for use in the construction industry. Another benefit of the high-pressure, direct-contact design is a steam generator with a much smaller environmental footprint.
Source: Natural Resources Canada
This article appears in the Oct. 2013 edition of PLANT.