DCSG to replace conventional generation.
The CanmetENERGY research centre in Ottawa and Canada’s Oil Sands Innovation Alliance (COSIA) are working on a direct contact steam generation (DCSG) technology intended to replace conventional generation.
Large amounts of fresh and saline groundwater are used to create steam for the steam-assisted gravity drainage (SAGD) process.
“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, research scientist, Combustion Technologies, CanmetENERGY.
Clements says the project was chosen for its potential as a transformative technology that addresses oil sands environmental issues.
The technology combusts fuel with pure oxygen at high pressure. Wastewater contaminated with hydrocarbons and dissolved or suspended solids, such as the type produced from SAGD and present in tailings ponds, creates a flue gas stream that’s 90% steam and 10% carbon dioxide (CO2). Trials have shown the process to have a thermal efficiency of nearly 100%.
The technology represents a new method of producing steam for heavy oil extraction that involves pumping the flue gas stream underground where CO2 is sequestered. In addition to energy savings, atmospheric CO2 emissions are diverted making this technology transformative in terms of the carbon intensity of oil sands-derived fuels.
Clements says to date, firing has been successful and will pave the way for the construction of a DCSG pilot plant capable of going up to 100 bar. It will use process water with high solids and hydrocarbon contamination directly fired with natural gas. He expects that other waste fuels, such as petroleum coke and asphaltene, could be combusted, and eventually, a demonstration DCSG plant might be feasible.
Clements notes the process also produces an inert, vitreous slag, a by-product potentially usable in the construction industry. And its high-pressure, direct-contact design means the steam generator has a much smaller environmental footprint.
Source: Natural Resources Canada
This article appears in the Nov./Dec. 2013 issue of PLANT West.