Systems and methods for generating carbon dioxide for use as a reforming oxidant in making syngas or reformed gas
Processes that generate syngas or reformed gas that have the desired H2/CO ratio, such that they can be used directly for producing higher value liquids, such as using a FT GTL process. The systems and methods of the present invention are simpler and more cost effective than conventional systems and methods. The systems and methods of the present invention generate the required CO2 in a reforming furnace by combusting natural gas with a mixture of O2 from an external source and CO2 that is recirculated from a reforming furnace. A second application of the natural gas combustion with external O2 mixed with recirculated CO2 in the reformer burners can be utilized in a DR process. The reformed gas or syngas containing H2 and CO is used to reduce iron oxide to metallic iron in a shaft furnace, for example.
1. A process for generating syngas or reformed gas that comprises a desired H2/CO ratio, comprising:
generating CO2 in a reforming furnace by combusting natural gas with a mixture of O2 from an external source and cooled recirculated CO2 from the reforming furnace;
wherein the combustion of the O2 and the natural gas produces CO2 and H2O;
splitting the produced CO2 into two streams;
wherein a first produced CO2 stream is compressed, and then is mixed with steam and additional natural gas and is sent as a process gas to reformer tubes in the reforming furnace where the produced CO2 of the first produced CO2 stream and H2O forming the steam reform the additional natural gas to H2 and CO;
wherein a second produced CO2 stream having a greater flow than the first produced CO2 stream is compressed, mixed with the O2 from the external source, and sent to reformer burners in the reforming furnace where the natural gas is combusted to produce the CO2 and H2O; and
wherein a H2/CO ratio of the syngas or reformed gas derived from the reformer tubes in the reforming furnace is 2 or less and the syngas or reformed gas is used directly in a Fischer-Tropsch gas-to-liquid process.
2. The process of claim 1 , wherein the cooled recirculated CO2 is continually recirculated from the reforming furnace to a heat exchanger, then to a scrubber that condenses a majority of the water.
3. The process of claim 1 , wherein the first produced CO2 stream is compressed to about 2-4 barg.
4. The process of claim 1 , wherein the second produced CO2 stream is compressed to about 0.5 barg.
5. The process of claim 1 , wherein cooled syngas or reformed gas is treated for delivery to a syngas processor.
6. The process of claim 1 , wherein a portion of the generated CO2 is delivered to and utilized in an additional reformer.
7. The process of claim 1 , wherein a portion of the cooled recirculated CO2 is received from an additional reformer.