| abstract |
Described is a method for sequestering carbon dioxide from a top gas fuel in a direct reduction process, including: given a top gas divided into a process gas and a top gas fuel, mixing the process gas with a hydrocarbon and feeding a resulting reformer feed gas into a reformer for reforming the reformer feed gas and forming a reducing gas, and feeding at least a portion of the top gas fuel into a carbon dioxide scrubber comprising one of a pressure swing adsorption (PSA) unit, a vacuum pressure swing adsorption (VPSA) unit, and a membrane separator for removing at least some carbon dioxide from the top gas fuel and forming a carbon dioxide lean gas that is selectively mixed with the reducing gas. A volume ratio of the process gas to the top gas fuel is responsive to available heat in the reformer to which the reformer feed gas is fed, and the volume ratio of the process gas to the top gas fuel is 1:1 when the carbon dioxide lean gas is fully utilized for mixing with the reducing gas and is 2:1 when the carbon dioxide lean gas is not utilized for mixing with the reducing gas. Also described is an apparatus useful in the method, and a corresponding method for sequestering carbon dioxide from a waste gas and reusing it as a recycled gas without emissions concerns. |