Process for Remote Lox/Lin Production by Hpair Turbo Expansion

This application claims the benefit of priority under 35 U.S.C. § 119(a) and (b) to U.S. Provisional Patent Application No. 63/571,178, filed Mar. 28, 2024, the entire contents of which are incorporated herein by reference.

It is the object of the present application to provide an improved process for the separation and liquefaction of oxygen and/or nitrogen. It is the objective to provide LOX and/or LIN at a customer site which may be remote, has limited space for process equipment, or other reasons not to have ASU and compression of liquefaction near LOX and LIN use location (for example: rocket launch pad or offshore platform).

When it is not feasible to locate production equipment near the point of use of the product liquid oxygen and/or liquid nitrogen the current practice is to locate production equipment away from site. Liquid products (LOX, LIN, . . . ) is loaded into trucks and transported to the site where the trucks are offloaded into liquid storage tanks near the site or offloaded directly into liquid product use point.

Alternatively, the air separation and liquefaction production equipment may be located adjacent to (say between 50 m to 1 km) the LOX and LIN use point. Whereby, these liquid products may be transferred from the production location to use location by pumps and highly insulated pipes. i.e. vacuum jacketed (VJ) insulated pipe. However, as the distance increases, such VJ piping is extremely expensive yielding this solution cost prohibitive.

Alternatively it is also known to produce and compress O2 and N2 molecules by cryogenic air separation at one location, then transport the pressurized gas in pipelines to a liquefaction unit. The liquefaction unit requires power and compression equipment to provide the refrigeration energy needed for the liquefaction, yielding two separate electrical and/or compression and drive systems at the ASU and Liquefier These compression and electrical systems occupy significant space and require significant power be available near the user location which may not be feasible.

It is desirable to have a system for producing and liquefying O2 and/or N2 and delivering to a use location without transporting the products by trailer, and without significant compression and power near the liquid product use location.

A process for cryogenic air separation and liquefaction, including purifying and compressing an inlet air stream, thereby producing a compressed inlet air stream, dividing the compressed inlet air stream into an ASU portion and a liquefaction portion, introducing the ASU portion into an air separation unit, thereby producing a gaseous oxygen steam and a gaseous nitrogen stream, and introducing the liquefaction portion, the gaseous oxygen steam and the gaseous nitrogen stream into a liquefaction unit, thereby producing a liquid nitrogen stream and a liquid oxygen stream. Wherein the air separation unit is located more than 200 meters from the liquefaction unit, and there is no compression driven by external energy within 200 meters of the liquefaction unit.

Illustrative embodiments of the invention are described below. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

A new and unforeseen arrangement is proposed wherein there are no power driven compression or refrigeration equipment near (say <100 m) the liquefaction unit. The energy for liquefaction is provided by pressurized dry air from the ASU located >100 m (preferably >500 m) from the liquefaction unit. The same air compressor and booster compressor and purification system used to produce dry air for the O2 and N2 separation and compression (typically between 40 bara to 80 bara) may also be used to produce additional high pressure dry air (40 to 80 bara) to the liquefier. The pressurized dry air to the liquefier is turboexpanded to produce the liquefaction energy without external compression energy. In one embodiment the pressurized air is turboexpanded to preferably <2 bara and vented or recycled.

Turning to, Inlet air streamenters front end purification unit, thereby producing purified inlet air. Purified inlet air streamis introduced into main air compressor, thereby producing compressed inlet air stream. Compressed inlet air streamis split into ASU portionand liquefaction portion. ASU portionis introduced into ASU expander, thereby producing cooled ASU air stream. Cooled ASU air streamis introduced into ASU, which produces at least gaseous nitrogen stream (GAN), and gaseous oxygen stream (GOX).

Liquefaction portionis introduced into liquefaction expander, thereby producing cooled liquefaction air stream. Cooled liquefaction air stream, gaseous nitrogen stream, and gaseous oxygen streamenter liquefaction unit, thereby producing at least liquid nitrogen streamand liquid oxygen stream. Liquid nitrogen streammay be introduced into liquid nitrogen storage unit. Liquid oxygen streammay be introduced into liquid oxygen storage unit. In one embodiment no addition refrigeration energy is withinmeters of the liquefaction unit. The addition refrigeration energy may be derived from electrical, steam, and/or hydrocarbon containing gas turbine compressor drives. Liquefaction portionmay be between 30 bara and 100 bara. Cooled liquefaction air streammay be less than 3 bara, preferably less than 2 bara. ASU portionhas a first flowrate, and liquefaction portion has a second flowrate. The ratio of the first flowrate to the second flowrate is between 1.0 and 2.0, preferably.. Liquid nitrogen streamhas a third flowrate, and liquid oxygen streamhas a fourth flowrate. The third flowrate plus the fourth flowrate is the fifth flowrate. The ration of the second flowrate to the fifth flowrate is between 2.0 and 4.0, preferably between 2.5 and 3.0. In one embodiment natural gas may be introduced into liquefaction unitand liquefied.

Turning to, at least a portion of the work produced by liquefaction expandermay be used to drive inlet air booster. At least a portion of the work produced by liquefaction expandermay be used to drive gaseous oxygen stream compressor, thereby producing boosted gaseous oxygen stream, which is then introduced into liquefaction unit. At least a portion of the work produced by liquefaction expandermay be used to drive gaseous nitrogen stream compressor, thereby producing boosted gaseous nitrogen stream, which is then introduced into liquefaction unit. At least a portion of the work produced by liquefaction expandermay be used to produce electricity E in electrical generatorwhich may be located near (within 100 meters) of liquefaction unit. In some embodiments, natural gas streamenters liquefaction unit, is liquefied, thus producing liquefied natural gas stream.

Turning to, in one embodiment liquefaction portion compressorprovides additional compression to liquefaction portion, thereby producing further compressed liquefaction portion, which is then introduced into liquefaction expander. At least a portion of the turboexpanded air is recycled and mixed with liquefaction portionand recompressed in compressor.

Turning to, in one embodiment, the air pressure of stream(second pressure) to liquefaction unit is a higher pressure than the air pressure of stream(first portion) to the ASU unit. The ratio of the second pressure to the first pressure is between 1.3 and 2.3, preferably between 1.5 and 1.8.

Turning to, air separation unitmay be located at least 200 meters, preferably 500 meters, from liquefaction unit.

It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.