Method and apparatus for pressurized product production

A method of producing a pressurized product stream comprising:

• rectifying a feed stream containing oxygen and nitrogen by a cryogenic rectification process utilizing a main heat exchanger of plate-fin construction and a distillation column system operatively associated with the main heat exchanger;
• pumping a product stream withdrawn from the distillation column system and composed of oxygen-rich liquid or nitrogen-rich liquid to produce a pumped product stream;
• warming at least part of the pumped product stream within layers of the main heat exchanger to produce the pressurized product stream and warming or cooling one other stream within said layers;
• the layers providing a heat transfer area within the main heat exchanger for the warming of the at least part of the pumped product stream that decreases, at least in part, by provision of regions within layers for warming or cooling of the one other stream, the regions positioned within the layers such that the heat transfer area decreases at a location of the main heat exchanger at which a temperature is reached within the main heat exchanger that exceeds the critical or dew point temperature of the pumped product stream the layers of the main heat exchanger include a first set of layers and a second set of layers, each of the first set of layers and the second set of layers have first sections and second sections;
• subsidiary streams composed of the at least part of the pumped product stream are introduced into the first sections of the first set of layers and the second set of layers;
• the subsidiary streams, after having been warmed within the first sections, are combined and introduced into the second sections of the first set of layers as combined subsidiary streams;
• the combined subsidiary streams are further warmed within the second sections of the first set of layers;
• the pressurized product stream is made up of the combined subsidiary streams after having been further warmed in the second sections of the first set of layers;
• the regions are formed by the second sections of the second set of layer.