The client needed to augment supply of CO2 for injection in an enhanced oil recovery (EOR) project, and was using expensive trucked-in CO2 as a stopgap supply. A nearby steam methane reformer offered a potential local source. The CO2 generated in the reformer, however, leaves the process in the reformer tail gas, diluted with hydrogen and unreacted methane. This could not be used directly, because the client needed 90% pure CO2 for the EOR project.
MTR proposed this scheme to recover 90% pure CO2 from the reformer. Because the CO2-rich tail gas is at low pressure, gas coming directly from the reformer provides a better source for CO2 recovery. In the solution developed by MTR, the Polaris™ membrane is used to permeate CO2 out of the pressurized reformer gas. Because hydrogen is fairly concentrated in this stream, some hydrogen does co-permeate with the CO2. The permeating gas is therefore recompressed and passed through a second membrane stage. This stage permeates 90% pure CO2 for reinjection. The pressurized, CO2-depleted gas leaving this stage is recycled back to the feed.
This simple process increases the CO2 concentration from 20% in the gas from the reformer to >90% in the recovered CO2 stream, and recovers nearly 75% of the CO2 contained in the reformer gas.