Process for the co-production of methanol and ammonia
A process for the combined preparation of methanol and ammonia based on primary steam reforming a hydrocarbon feed stock and adiabatic secondary reforming with oxygen enriched air from electrolysis of water.
1. Process for the co-production of methanol and ammonia comprising the steps of:
(a) providing a hydrocarbon feed stock;
(b) preparing a separate hydrogen stream and a separate oxygen stream by electrolysis of water;
(c) primary steam reforming the hydrocarbon feed stock provided in step (a) to a primary steam reformed gas;
(d) providing process air for use in a secondary reforming step by enriching atmospheric air with the separate oxygen stream from step (b);
(e) secondary reforming the primary steam reformed gas from step (c) with the oxygen enriched air to a process gas stream comprising hydrogen, nitrogen, carbon oxides;
(f) introducing at least part of the separate hydrogen stream from step (b) into the process gas stream obtained in step (e), or optionally into the process gas stream after a shift and/or carbon dioxide removal step;
(g) catalytically converting the carbon oxides and a part of the hydrogen contained in the process gas stream in a once-through methanol synthesis stage and withdrawing an effluent containing methanol and a gas effluent containing un-converted carbon oxides, hydrogen and nitrogen, wherein the hydrogen prepared by electrolysis of water is introduced into the process gas stream in step (f), prior to the methanol synthesis, by introducing the hydrogen into a suction section of a process gas compressor in an amount to adjust a hydrogen/nitrogen molar ratio in the gas effluent to a stoichiometric ratio of 2.7-3.3 required for production of ammonia;
(h) purifying the gas effluent from step (g) and obtaining an ammonia synthesis gas containing hydrogen and nitrogen; and
(i) catalytically converting the nitrogen and the hydrogen of the ammonia synthesis gas in an ammonia synthesis stage and withdrawing an effluent containing ammonia.
2. Process of claim 1 , wherein at least a part of the process gas stream from step (e) is subjected one or more water gas shift reactions.
3. Process of claim 1 , wherein at least a part of the process gas stream from step (e) is subjected to carbon dioxide removal.
4. Process of claim 1 , wherein the purifying of the gas effluent in step (h) comprises methanation.
5. Process of claim 1 , wherein the purifying of the gas effluent in step (h) comprises a cryogenic process.
6. Process of claim 1 , wherein the electrolysis of water in step (b) is powered by renewable energy.