Flexible process for converting carbon dioxide, hydrogen, and methane into synthesis gas
The present invention relates to a process for converting feed streams selected from (1) a gas stream comprising carbon dioxide and a hydrogen rich gas stream; (2) a methane rich gas stream; and (3) a combination of feed streams (1) and (2) into a product stream comprising carbon monoxide, water and hydrogen. The process may include introducing feed streams selected from (1), (2) or (3) and oxygen into a reaction vessel and switching modes between performing method I or method II in the reaction vessel wherein no catalyst is present. The reaction vessel may be provided with a burner located at the top of the reaction vessel, the burner may include coaxial channels for the separate introduction of the different gas streams. Method I may be a reverse water gas shift reaction at elevated temperature. Method II may be a partial oxidation reaction at elevated temperature.
1 . A process for converting feed streams selected from (1) a gas stream comprising carbon dioxide and a hydrogen rich gas stream; (2) a methane rich gas stream; and (3) a combination of feed streams (1) and (2) into a product stream comprising carbon monoxide, water and hydrogen, the process comprising:
introducing the feed streams selected from (1), (2) or (3) and oxygen into a reaction vessel;
in switching mode, performing method I or method II in the reaction vessel, wherein no catalyst is present, the reaction vessel being provided with a burner located at the top of the reaction vessel, the burner comprising coaxial channels for the separate introduction of the feed streams and the oxygen:
in method I, performing a reverse water gas shift reaction at an elevated temperature, wherein (a) at least feed stream (1) and an oxygen rich gas stream are introduced into the reaction vessel via the burner in separate feed streams, wherein the hydrogen rich gas stream is introduced into the reaction vessel at a temperature between 15 and 500° C., (b) the hydrogen rich gas stream and the oxygen rich gas stream being introduced in close vicinity of each other, wherein the hydrogen and the oxygen in the hydrogen rich gas stream and the oxygen rich gas stream, respectively, undergo a combustion reaction upon entering the reaction vessel, thereby providing the heating energy required for the reverse water-gas shift reaction; and (c) the temperature in the reaction vessel is maintained in the range of 1000 to 1500° C. by varying the molar ratio of the hydrogen to the oxygen, which are introduced into the reaction vessel in the hydrogen rich gas stream and the oxygen rich gas stream, respectively; and
in method II, performing a partial oxidation reaction at an elevated temperature, wherein (d) at least feed stream (2) and an oxygen rich gas stream are introduced into the reaction vessel via the burner in separate feed streams, (e) the feed stream (2) and the oxygen rich gas stream being introduced in close vicinity of each other, wherein the feed stream (2) and the oxygen rich gas stream undergo the partial oxidation reaction upon entering the reaction vessel; and (f) the temperature in the reaction vessel is maintained in the range of 1100 to 1500° C. by varying the flow rate of the oxygen and/or the feed stream (2); wherein during the switching mode from method I to method II or vice versa, the feed streams are gradually changed to the relevant feed streams, so that the feed stream (3) is present in an intermediate phase, the feed streams being introduced via the appropriate channels, while also changing the temperature of the reaction vessel to the desired temperature for the relevant method.
2 . The process according to claim 1 , wherein the feed streams can be selected without change in equipment or stopping the process by either gradually increasing the flow of the feed stream (1) while gradually decreasing the flow of the feed stream (2), and vice versa, or by opening and closing valves of the respective feed streams feeding to the burner, while continuing the flow of the oxygen and adapting that as required.
3 . The process according to claim 1 , wherein, in the process, the percentage of the feed streams (1) and (2) in the feed stream (3) may be varied over time as required along with the variation of the oxygen rich gas stream.
4 . The process according to claim 1 , wherein the reaction vessel is preheated to a temperature ranging up to 1100° C.
5 . The process according to claim 1 , wherein one or more feed streams selected from the feed streams (1) and (2) along with the oxygen rich gas stream are preheated before being introduced into the reaction vessel.
6 . The process according to claim 1 , wherein at least part of the hydrogen rich gas stream and/or at least part of the oxygen rich gas stream in the feed streams is obtained from a water splitter.
7 . The process according to claim 1 , wherein, in the method I, part of the gas stream comprising carbon dioxide is introduced via a channel in between the hydrogen rich gas stream and the oxygen rich gas stream and the remaining part of the gas stream containing carbon dioxide is introduced in an outer channel of the burner, wherein the outer channel of the burner is outside of the channels for the hydrogen rich gas stream and the oxygen rich gas stream.
8 . The process according to claim 1 , wherein, in the method I, the oxygen rich gas stream is introduced via an inner channel(s) of the burner.
9 . The process according to claim 1 , wherein, in the method II, the oxygen rich gas stream is introduced via an inner channel(s) of the burner.
10 . The process according to claim 1 , wherein, in both of the methods I and II, the oxygen rich gas stream is introduced via an inner channel(s) of the burner.