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Method For High Pressure Oxygen Production

IP.com Disclosure Number: IPCOM000019409D
Publication Date: 2003-Sep-12
Document File: 5 page(s) / 40K

Publishing Venue

The IP.com Prior Art Database

Abstract

The air separation industrial gas market (oxygen, nitrogen, argon) generally requires products at pressures below 500 psig (35 barg). Air separation companies supply oxygen to a number of refinery customers at pressures of 1,000 - 1,200 psig (68 – 83 barg). Energy project developers have recently expressed interest for the supply of gaseous oxygen at pressures over 2,000 psig (138 barg) with some applications approaching 5,000 psig (345 barg).

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Method For High Pressure Oxygen Production

Introduction

The air separation industrial gas market (oxygen, nitrogen, argon) generally requires products at pressures below 500 psig (35 barg). Air separation companies supply oxygen to a number of refinery customers at pressures of 1,000 - 1,200 psig (68 – 83 barg). Energy project developers have recently expressed interest for the supply of gaseous oxygen at pressures over 2,000 psig (138 barg) with some applications approaching 5,000 psig (345 barg).

The flow requirements for these applications will drive the basic process selection toward the use of cryogenic distillation processes. Oxygen can be delivered by a) compressing a low pressure stream produced from the distillation and heat exchange systems, b) pumping a liquid oxygen stream from the distillation system to an intermediate pressure, vaporizing and warming the oxygen, followed by gaseous compression to the final pressure, or c) pumping the oxygen stream to final delivery pressure followed by warming. Other basic process options such as adsorption and membrane separation would require low pressure gaseous oxygen compression systems.

The following article discusses the various approaches for cryogenic process options and describes methods to use essentially proven equipment to produce tonnage quantities (over 200 tons per day) of oxygen above 2,000 psig (138 barg).

Gaseous Oxygen Compression

In the 1980s compression of oxygen streams to pressures of about 2,200 psig (152 barg) was successfully demonstrated based on the use of a “barrel” type centrifugal compressor. Prior to this demonstration, oxygen delivery pressure for pipeline quantities had been limited to about 1,200 psig (83 barg). For large scale industrial requirements, compression choices are limited to reciprocating or centrifugal units. Although high pressure compression equipment exists for gases other than oxygen, designing for oxygen supply above about 2,500 psig (172 barg) will require concept development, materials analysis, sealing design, a thorough hazards and operability analysis and potentially a demonstration scale unit and proof of concept testing and analysis program. In addition to the mechanical issues, compression efficiency may be very low due to diminishing volumetric flow at the higher end of the compression range.

Pumped Liquid Oxygen

In the 1990s there was increasing use of pumped liquid oxygen or “internal compression” cycles, wherein liquid oxygen from the cryogenic distillation column is pumped and vaporized against an air or nitrogen stream (working fluid) that returns the refrigeration in the liquid oxygen to the distillation system. Figure 1 shows the schematic of a typical pumped LOX process, wherein PO is the pressure of the oxygen stream obtained by pumping and PW is the pressure of the working fluid. In the case shown, a portion of the feed air is boosted in pressure and used as the working fluid. Liquid oxygen is pumped to the final...