A method is described for increasing the production in an existing process plant for converting natural gas to a product, wherein the synthesis gas from the synthesis gas section receives a hydrogen-rich stream from the separated purge gas, and that this hydrogen enriched synthesis gas is passed through a new flow reactor for production of product, and also a unit for separating a product-rich stream that is taken off, and a product-poor stream used as feed to the original reactor, and that the product-poor stream, which is used as feed to the original reactor, receives additional synthesis gas produced in a separate secondary synthesis gas line.