History of The Petroleum Industry in Canada (natural Gas) - Canada's First Sweetening Plant

Canada's First Sweetening Plant

Sour gas, as it is known, in its natural state is laced with hydrogen sulfide (H₂S), which can be lethal if inhaled in even tiny concentrations. (The more general term acid gas refers to natural gas with any acidic gas in it - carbon dioxide (CO₂), for example.)

The process of taking hydrogen sulfide out of a gas stream is called "sweetening" the gas. The Union Gas Company of Toronto built Canada's first sweetening plant in 1924 at Port Alma, Ontario, to scrub Tillbury gas. Hydrogen sulfide is a dangerous substance which at low concentrations has an obnoxious rotten egg smell. This odour annoyed Union's customers and prompted it to build the Port Alma plant. It removed hydrogen sulfide by exposing the sour gas to dissolved soda ash. Although previously used on coal gas, the application at the Port Alma plant was the first time this process sweetened natural gas.

The second Canadian sweetening plant followed a year later in Turner Valley, and used the same process. The first gas found at Turner Valley had been sweet but the Royalite #4 discovery of 1924, from a deeper horizon, was sour. Royalite built the Turner Valley sweetening plant in order to sell its gas to Canadian Western Natural Gas for distribution.

The technology of the day did not render the hydrogen sulfide harmless. Instead, the producer disposed of the substance by burning it and dispersing the by-products into the air from two tall stacks. One chemical result of burning hydrogen sulfide emissions was sulfur dioxide, another toxic gas. Since hydrogen sulfide is heavier than air, it settled to the ground, dispersed enough to be less than lethal.

Hydrogen sulfide was always in the air in small concentrations. Turner Valley had a rotten egg odour on most days.