Patent EA-004084-B1 (EA)
Title: Method and plant for production of oxygenated hydrocarbons
Inventor: SOGGE JOSTEIN
IPC: C07C41/01
Filed: 2000-12-28
Abstract: 1. A method for increasing production in an existing process plant for converting natural gas to a product, wherein the natural gas is first converted into a synthesis gas in a synthesis gas section; the synthesis gas is reacted in a reactor for synthesis of the product, where non-converted synthesis gas and product are separated into two streams, where a product-rich stream is taken out of the process, whilst a product-poor stream is recycled as feed to the reactor together with make-up synthesis gas, where a portion of the recycle stream is taken out of the recycle loop as a purge gas, where the purges gas is separated into hydrogen-rich and hydrogen-poor streams, where the hydrogen-rich stream is introduced into steps in the process where it is desirable to have a supplement of hydrogen, and where the residual thermal value in the hydrogen-poor stream optionally is used for heating before it is discharged, characterised in that the synthesis gas from the synthesis gas section is fed with a hydrogen-rich stream from the separated purge gas and that this hydrogen-enriched synthesis gas is passed through a new once-through reactor for production of the product and through a unit in order to separate a product-rich stream that is taken out, and a product-poor stream that is used as feed in the original reactor. 2. A method according to claim 1, characterized in that the product-poor stream that is used as feed for the original reactor is fed with, additional synthesis gas which is produced in a separate secondary synthesis gas line. 3. A method according to claim 2, characterized in that the new synthesis gas line is based on ATR or POX. 4. A method according to one or more of the preceding claims. Characterized in that the product is methanol or dimethyl ether. 5. A processing plant for producing a product on the basis of natural gas, where the processing plant comprises a synthesis gas section (2,3,4,5,6,7,8) for producing synthesis gas that essentially consists of CO, CO2, H2 and water, a synthesis section (14) where the product is formed, and purification section (13,17) where the product is separated from unconverted reactants and other substances and is purified, where unconverted reactants that are separated from the product are recycled to the synthesis section (14), where a portion of the gas that is recycled is drawn off in a line (19) in order to prevent a build-up of inert gases, and where the plant comprises a separation unit (20) for separating the gas that is drawn off in line (19) into hydrogen-rich and hydrogen-poor fractions, a line (22) for conveying hydrogen-poor fractions to optional combustion, and lines (21,23) for leading hydrogen-rich fractions into the natural gas feed and for recycling to the synthesis section (14) respectively, characterized in that between the synthesis gas section (2,4,8) and the synthesis section (14) there is provided a once-through reactor (25) for synthesis of the product, and a separation unit (33) for separation of a product-rich fraction to a line (27) and a product-poor fraction to a line (26, 26b), that leads to the synthesis section (14). 6. A processing plant according to claim 5, characterized in that it also comprises a separate secondary synthesis gas line (28,29,31,30) for producing a secondary synthesis gas, and a line (32) to lead the secondary synthesis gas as feed for the synthesis section (14).