SNG Plant

How SNG is made and Distributed

The first step is the removal of sulfur contained in the hydrocarbon feedstock. The feedstock is blended with hydrogen gas, heated to 700 degrees Fahrenheit and sent through a reactor vessel containing a cobalt-molybdenum catalyst and a zinc-oxide reactant. The end result is a chemical reaction that removes the sulfur from the feedstock by converting it to zinc sulfide.
The purified feedstock then proceeds to a series of reactors, where it is blended with super-heated steam and passed through a catalyst of nickel pellets. The result is methane, hydrogen and carbon dioxide. After the reactors, the gas flows in two separate directions.

One flow is to a carbon dioxide absorber to remove the carbon dioxide. Then, an odorant is added to give the odorless gas the familiar "gas" smell.

This is an important safety measure. Next, butane is added to give the SNG additional heating value so that it can be properly burned by customers. (The left over carbon dioxide is sent to a regenerator and prepared for sale to another company that will process it further.) Finally, this SNG is channeled into the distribution system at about 450 pounds of pressure, traveling through transmission and distribution lines to homes and businesses.

The other flow of SNG is into the hydrogen gas production plant. The products of this plant are hydrogen and carbon dioxide gas. The carbon dioxide is removed and sold to companies that manufacture dry ice and liquid carbon dioxide. The hydrogen flows back into the desulfurization step that began the whole process. Or it may be returned to the refinery for use in the petroleum refining process.

Gas Facts