| 摘要 |
Natural gas is converted with steam and oxygen in an autothermally operated reactor, and from the reactor a raw synthesis gas with a temperature in the range from 800 to 1200.degree.C is withdrawn. To the cooled, raw synthesis gas a gas rich in H2 is admixed. The synthesis gas with an increased H2 content is converted in a methanol synthesis reactor on a copper catalyst at a pressure in the range from 10 to 150 bar and temperatures from 180 to 350.degree.C. From the synthesis reactor a gas mixture containing methanol vapor is withdrawn, methanol is condensed out, and a cooled residual gas is separated. The residual gas is divided into a first partial stream (recycle gas) and a second partial stream (purge gas). The recycle gas is admixed to the synthesis gas before the methanol synthesis reactor. The purge gas consists of 30 to 80 vol-% H2, 7 to 35 vol-% CO2 and 3 to 25 vol-% CO. The hourly quantity of purge gas is 8 to 25 % (calculated dry) of the hourly quantity of raw synthesis gas. The purge gas is charged into a separating means, where the gas rich in H2 is recovered, which is admixed to the raw synthesis gas. The hourly quantity of carbon dioxide supplied to the separating means in the purge gas is 10 to 50 % of the hourly quantity of CO2 in the raw synthesis gas. |
