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WARM EXPANDER APPLICATIONS IN AIR SEPARATION

IP.com Disclosure Number: IPCOM000032922D
Publication Date: 2004-Nov-18
Document File: 3 page(s) / 52K

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WARM EXPANDER APPLICATIONS IN AIR SEPARATION

Sometimes an air separation unit (ASU, typically comprising high-pressure and low-pressure cryogenic distillation columns) is located in proximity of a heat source. For example, it supplies oxygen to a gas-to-liquid process (GTL). GTL often produces excess steam that can be used as a source of heat. This heat can be used to preheat a gas expander and generate power or shaft work.

Figure 1

Figure 1 shows arrangement described in German patent DE 201 20 111 U1. ASU produces gaseous oxygen (GOX), typically low-purity (less that about 98% O2). Air is compressed in the main air compressor (MAC). A portion of air heated up, for example against steam, expanded in an expander (EXP), and fed to the ASU at low pressure, for example to the low-pressure column. Expander supplies at least a portion of energy required to drive at least one stage of MAC.

Figure 2

Figure 2 shows a variation. A portion of air taken from the discharge of a booster air compressor (BAC) is heated up, for example against steam, expanded in an expander (EXP) and fed to the ASU at a higher pressure, for example to the high-pressure column. It can be combined with MAC air. Expander supplies at least a portion of energy required to drive at least one stage of MAC. This arrangement may be applicable to both low-purity and high-purity (greater than about 98% O2) GOX. Typically, BAC air is liquefied against boiling liquid oxygen. It can also go the mixing column. It is possible to expand a...