Apparatus and method of heating pumped liquid oxygen

A heat exchanger for heating a stream of liquid oxygen at a pressure of at least about 30 bar by indirect heat exchange against a heat exchange fluid, said heat exchanger comprising:

• a stack of ferrous alloy plates, each plate having a laterally spaced plurality of walls defining channels extending across the surface of the plate and each plate being in thermal contact with at least one other plate in the stack;
• oxygen inlet means for introducing pumped liquid oxygen at a pressure of at least about 30 bar into the channels of at least one plate , hereafter “oxygen plates”;
• oxygen outlet means for removing heated oxygen from said channels of the oxygen plates;
• heat exchange fluid inlet means for introducing heat exchange fluid into the channels of at least one plate, hereafter “heat exchange plates”, adjacent an oxygen plate in thermal contact therewith;
• heat exchange fluid outlet means for removing cooled heat exchange fluid from said channels of the heat exchange plates;
• wherein said walls between adjacent channels in each oxygen plate and the walls between said channels in the oxygen plate and channels in an adjacent plate each have a cross-section, in a plane perpendicular to the direction of flow through the adjacent channels, having a thickness which at its narrowest is at least about 10% of the combined hydraulic mean diameters of the two adjacent channels and on average is at least about 15% of said combined hydraulic mean diameters, and the ratio of cross-sectional area, in said plane, of the mass of each oxygen plate, including walls, to the cross-sectional area of the channels therein is at least about 0.7.

A process for providing a stream of high pressure gaseous oxygen comprising introducing a pumped liquid oxygen stream at a pressure of at least about 30 bar into channels of at least one layer, hereafter “oxygen layers” of a heat exchange body having a plurality of spaced layers of transversely extending laterally spaced channels defined by ferrous alloy walls with each layer being in thermal contact with at least one other layer and heating said oxygen stream during passage through said channels in the oxygen layers by indirect heat exchange with a heat exchange fluid passing through channels of at least one layer, hereafter “heat exchange layers” adjacent an oxygen layer in thermal contact therewith;

• wherein the walls between adjacent channels in each oxygen layer and the walls between said channels in the oxygen layer and channels in an adjacent layer each have a cross-section, in a plane perpendicular to the direction of flow through the adjacent channels, having a thickness which at its narrowest is at least about 10% of the combined hydraulic mean diameters of the two adjacent channels and on average is at least about 15% of said combined hydraulic mean diameters, and the ratio of cross-sectional area, in said plane, of the mass of the ferrous alloy walls defining the channels in each oxygen layer to the cross-sectional area of the channels in that layer is no less than about 0.7.

A cryogenic process for the separation of air to provide a high pressure gaseous oxygen stream comprising separating a feed air stream in a distillation column system to provide at least a liquid oxygen stream and a gaseous nitrogen stream;

• pumping said liquid oxygen stream to a pressure of at least about 30 bar;
• and heating the pumped liquid oxygen by introducing it into channels of at least one layer, hereafter “oxygen layers”, of a heat exchange body having a plurality of spaced layers of transversely extending laterally spaced channels defined by ferrous alloy walls with each layer being in thermal contact with at least one other layer and heating said oxygen stream during passage through said channels in the oxygen layers by indirect heat exchange with a heat exchange fluid, selected from air and a stream produced during the air separation, passing through channels of at least one layer, hereafter “heat exchange layers” adjacent an oxygen layer in thermal contact therewith;
• wherein the walls between adjacent channels in each oxygen layer and the walls between said channels in the oxygen layer and channels in an adjacent layer each have a cross-section, in a plane perpendicular to the direction of flow through the adjacent channels, having a thickness which at its narrowest is at least about 10% of the combined hydraulic mean diameters of the two adjacent channels and on average is at least about 15% of said combined hydraulic mean diameters, and the ratio of cross-sectional area, in said plane, of the mass of the ferrous alloy walls defining the channels in each oxygen layer to the cross-sectional area of the channels in that layer is no less than about 0.7.

A cryogenic process for the separation of air to provide a high pressure gaseous oxygen stream comprising separating a feed air stream in a distillation column system to provide at least a liquid oxygen stream and a gaseous nitrogen stream;

• pumping said liquid oxygen stream to a pressure of at least about 30 bar;
• and heating the pumped liquid oxygen by introducing it into channels of at least one plate, hereafter “oxygen plates”, of a stack of ferrous alloy plates, each plate having a laterally spaced plurality of walls defining channels extending across the surface of the plate and each plate being in thermal contact with at least one other plate in the stack and heating said oxygen stream during passage through said channels in the oxygen plates by indirect heat exchange with heat exchange fluid passing through channels of at least one plate, hereafter “heat exchange plates” adjacent an oxygen plate in thermal contact therewith;
• wherein said walls between adjacent channels in each oxygen plate and the walls between said channels in the oxygen plate and channels in an adjacent plate each have a cross-section, in a plane perpendicular to the direction of flow through the adjacent channels, having a thickness which at its narrowest is at least about 10% of the combined hydraulic mean diameters of the two adjacent channels and on average is at least about 15% of said combined hydraulic mean diameters, and the ratio of cross-sectional area, in said plane, of the mass of each oxygen plate, including walls, to the cross-sectional area of the channels therein is no less than about 0.7.