【正文】 cle fluid of the open cooling cycle involved in the separation steps. 11. The process according to claim 1, wherein carbon monoxide having a purity of at least 98% is produced. 12. In a plant for the bined production of an ammonia synthesis mixture and carbon monoxide prising cryogenic means for separating the constituents of a gas mixture containing essentially hydrogen and carbon monoxide, as well as other constituents including nitrogen and methane, including a heat exchanger, a source capable of providing a stream of nitrogen at high pressure and a column for washing with liquid nitrogen, the improvement wherein: the nitrogenwashing column prises means for drawing off liquid from a position intermediate between the base and the head of the column, and the plant further prises a mediumpressure stripping column provided with boiling means, producing a liquid fraction rich in carbon monoxide at the base, and hydrogen at the head。 62/920 Field of Search: 62/617,620,618,630,632,631,920 References Cited [Referenced By] . Patent Documents 4478621 October 1984 Fabian 4636334 January 1987 Skinner et al. 5295356 March 1994 Billy 5609040 March 1997 Billy et al. Foreign Patent Documents 38 01 712 March DE 0 092 770 March EP Primary Examiner: Doerrler。Air Liquide, Societe Anonyme pour l39。 ( 2 of 4 ) United States Patent 6,178,774 Billy , et al. January 30, 2020 Process and plant for the bined production of an ammonia synthesis mixture and carbon monoxide Abstract In the process of the invention, an ammonia synthesis mixture and carbon monoxide are produced. The hydrogen is purified in a nitrogenwashing column (61). The carbon monoxide is recovered cryogenically from a first liquid fraction (51) collected at the base of the said washing column (61), in a mediumpressure stripping column (62), then in a lowpressure distillation column (63). A second liquid fraction (52) is drawn from a position intermediate between the base and head of the washing column (61). Inventors: Billy。 Daniele (LimeilBrevannes, FR) Assignee: L39。 62/630。 and a second liquid fraction at an intermediate position between the base and head of the washing column, which is rich in nitrogen and lean in carbon monoxide。 and a line provided with expansion means for conveying the base liquid fraction from the stripping column to an intermediate position on the distillation column. 13. The plant according to claim 12, further prising an open nitrogen cooling cycle supplied with nitrogen at high pressure intended for the production of the ammonia synthesis mixture. 14. The plant according to claim 12, wherein the boiling means of the stripping and the distillation columns prise highpressure nitrogen lines respectively connected to the stream of nitrogen at high pressure. 15. The plant according to claim 12, further prising a feed line provided with expansion means connected to the stream of nitrogen at high pressure for supplying the lowpressure portion of the cooling cycle. 16. The plant according to claim 12, further prising an open CO cooling cycle supplied with the carbon monoxide produced and connected to a cycle pressor. 17. The plant according to claim 12, wherein said plant is integrated into equipment for synthesizing ammonia whose means of production of the synthesis mixture prise a first unit for partial oxidation of hydrocarbons or of coal, and a last unit for washing with nitrogen。 and means for cryogenically purifying the carbon monoxide from the first liquid fraction by a first separation under medium pressure in a stripping column separating the residual hydrogen at the head, and a second distillation under low pressure in a distillation column separating the carbon monoxide and the residual nitrogen at the head from the base mixture resulting from the first separation in the stripping column. Description FIELD OF THE INVENTION The present invention relates to the bined production of an ammonia synthesis mixture ( +) and carbon monoxide, as well as to a plant for such bined production. BACKGROUND OF THE INVENTION Conventionally, carbon monoxide is obtained during the steam reforming or partial oxidation of hydrocarbons. It is possible to produce highly pure carbon monoxide with such units by using conventional purification techniques. These include cryogenic processes such as partial condensation or washing with liquid methane。 treatment of the hydrogen sulphide output by step 2, at 11, by a Claus process to produce sulphur, and various heat exchangers 12 to 14. In the prior art, the residual gas from the nitrogenwashing step 6 is burned. A process for production of carbon monoxide, which makes it possible in the particular case above to utilize the residual gas rich in carbon monoxide is known from document EPA0,092,770. The residual gas is then used as feed mixture for the carbon monoxide production process. One of the processes described in that patent application includes a step of washing with methane in order to separate the hydrogen from a mixture also prising methane, carbon monoxide and nitrogen. The condensate thus produced is distilled in a first distillation column in order to separate methane from the rest of the mixture. The gas from the head of this first column, mainly containing carbon monoxide, is distilled in a second distillation column in order to extract the nitrogen and the hydrogen remaining, the pure carbon monoxide being drawn off from the base of this column. The carbon monoxide is then used as a coolant for the head condensers of the first and second columns. A process for production of carbon monoxide from the residua