| 摘要 |
<p>The invention relates to a method and device for generating gaseous compressed nitrogen by the low-temperature separation of air in a distillation column system, said distillation column system having a pre-column (41), a high-pressure column (42) and a low-pressure column (43). All the feed air is compressed in a main air compressor (103), purified in a purification apparatus (104) and cooled down in a main heat exchanger (2). A first sub-flow (11) of the cooled feed air is introduced in gaseous form into the pre-column (41). A second sub-flow (21) of the cooled feed air is introduced (23, 24) in a predominantly liquid state into the distillation column system. A gaseous fraction (51) from the upper region of the pre-column (41) is introduced into the liquefaction chamber of a pre-column head condenser (44). Liquid (52) formed in the liquefaction chamber is fed as reflux (53) into the pre-column (41). A first nitrogen product fraction (65) is drawn in gaseous form from the high-pressure column (42), heated in the main heat exchanger (2) and obtained as first gaseous compressed nitrogen product. At least a part (23) of the second sub-flow (21) is introduced into the evaporation chamber of the pre-column head condenser (44). A third sub-flow (34) of the cooled feed air is expanded to perform work (35) and subsequently (36) introduced into the liquefaction chamber of a bottom evaporator (45) of the low-pressure column and there at least partially liquefied. The liquefied third sub-flow (37, 38) is introduced into the low-pressure column (43). An intermediate liquid of the low-pressure column (43) is at least partially evaporated in the evaporation chamber of an intermediate evaporator (46) of the low-pressure column (43). A gaseous head fraction (59) from the high-pressure column (42) is as least partially liquefied in the liquefaction chamber of the intermediate evaporator (46), and liquid (59, 60) resulting therefrom is fed as reflux into the high-pressure column (42). More than 35 Mol % in the form of the first nitrogen product fraction (65), which is drawn in gaseous form from the high-pressure column (42), is heated in the main heat exchanger (2) and obtained as first gaseous compressed nitrogen product (66).</p> |
