Process for the manufacture of methyl tert.-butyl ether

Claim 1

A process for the manufacture of methyl tert.-butyl ether which comprises isomerizing n-butane to form isobutane in an isomerization stage, catalytically dehydrogenating resulting isobutane in a dehydrogenating stage to form an isobutane/isobutene mixture, steam reforming natural gas to form a synthesis gas containing CO and H 2 in a steam reforming stage, converting the resulting synthesis gas to methanol in a methanol synthesis stage, etherifying the resulting methanol with isobutene in the isobutene/isobutane mixture to form methyl tert.-butyl ether in an etherification mixture, separating isobutane from the etherification mixture, recycling separated isobutane to the dehydrogenation stage, burning secondary product gases from at least one of the isomerization, dehydrogenation and methanol synthesis stages in a combustion stage to form hot combustion gases, generating and superheating steam at high pressure by heat exchange with the resulting hot combustion gases, expanding at least a part of the resulting high pressure steam to a medium pressure in first back-pressure turbines coupled to compressors for the compression of the synthesis gas and of the dehydrogenation stage product gas, supplying part of resulting medium pressure steam as process steam to the steam reforming stage, expanding another part of said medium pressure steam in second back-pressure turbines to low pressure steam in excess of atmospheric pressure, and utilizing resulting low pressure steam for heating apparatus employed in said process for the manufacture of methyl tert.-butyl ether.