Patent ID: 7037948

Claim:
A method of increasing the production in an existing process plant for converting natural gas into a product, comprising: converting the natural gas to a synthesis gas in a synthesis gas section, the synthesis gas being brought to reaction in a first reactor for synthesis of the product; separating non-converted synthesis gas and product into two streams, wherein a product-rich stream is taken off the process, and a product-poor stream is re-circulated back as feed to the first reactor together with fresh synthesis gas; taking part of the product-poor stream off a re-circulation loop as a purge gas; separating the purge gas into hydrogen-rich and hydrogen-poor streams, where the hydrogen-rich streams are introduced in stages of the process where addition of hydrogen is desirable, and where the residual thermal value of the hydrogen-poor stream may be used for heating prior to the stream being discharged; wherein the synthesis gas from the synthesis gas section receives a first hydrogen-rich stream from the separated purge gas to form a hydrogen enriched synthesis gas; passing the hydrogen enriched synthesis gas through a second reactor for production of product, and also a unit for separating a second product-rich stream that is taken off, and a second product-poor stream used as feed to the first reactor; wherein the second product-poor stream, which is used as feed to the first reactor, receives additional synthesis gas produced in a separate secondary synthesis gas line comprising a pre-converter.