Process and apparatus for the production of gaseous oxygen under pressure

Claim 2

Process for production of gaseous oxygen at a pressure higher than approximately 13 bars by air distillation in an apparatus provided with a double column comprising a mean pressure column and a low pressure column, each of said mean and low pressure columns having a respective base and a respective pressure, said process including the steps of: i) withdrawing liquid oxygen at the base of said low pressure column; ii) pumping said withdrawn liquid oxygen; iii) introducing air to be distilled into a heat exchange line, said air being at a first high pressure lower than that at which air condenses by heat exchange with said pumped liquid oxygen, where said pumped liquid oxygen is at a pressure greater than approximately 13 bars, said first pressure being at least equal to approximately 30 bars; iv) vaporizing said pumped liquid oxygen by heat exchange with said air in said heat exchange line, to produce gaseous oxygen at a pressure higher than approximately 13 bars; v) withdrawing a portion of said air from said line, said portion being surplus to refrigerating needs of said line; vi) expanding said portion to the pressure of said mean pressure column at an intermediate cooling temperature in a turbine, said turbine being slowed down by a first compressor, said compressor being used in step iii) to pressurize all the air to be distilled to said first high pressure; and vii) withdrawing an amount of at least one liquid product from said apparatus as a final product.

Claim 3

Process according to claim 1, wherein for a first high pressure of approximately 30 bars, said amount of said liquid product withdrawn as a final product is approximately 25% by weight of the production of gaseous oxygen.

Claim 4

Process according to claim 1, wherein for production of gaseous oxygen at second and third pressures, respectively lower and higher than approximately 13 bars, two flows of compressed liquid oxygen are vaporized by heat exchange with compressed air at the first high pressure which is lower than that at which air condenses by heat exchange with oxygen at said third pressure during vaporization and at least equal to approximately 30 bars, and higher than that pressure at which air condenses by heat exchange with oxygen at said second pressure during vaporization.

Claim 5

Process according to claim 1, including compressing the air in first and second stages, said second stage being carried out by means of the first compressor which is operated by the turbine.

Claim 6

Process according to claim 1, including withdrawing liquid nitrogen under pressure from the double column, and vaporizing said withdrawn nitrogen, in the heat exchange line, with air at high pressure.

Claim 7

Process according to claim 1, wherein a portion of air at the pressure of the mean pressure column is, after separation of its liquid phase, expanded in a second turbine and is blown into the low pressure column.

Claim 8

Process according to claim 1, including withdrawing vat liquid from the base of the mean pressure column, expanding said liquid and introducing said liquid into said low pressure column.

Claim 9

Process for the production of gaseous oxygen at a pressure of at least approximately 13 bars, by introducing air to be distilled in an apparatus provided with a double column comprising a low pressure column and a mean pressure column, said mean pressure column having a pressure, including pumping of liquid oxygen which is withdrawn at the bottom of the low pressure column, and vaporization of the pumped liquid oxygen compressed by heat exchange with air pressurized to a high pressure which is substantially higher than the pressure of the mean pressure column, wherein said process comprises the steps of: i) compressing all the air to be distilled to a first high pressure which is considerably higher than the pressure of the mean pressure column; ii) cooling a first fraction of the compressed air; iii) expanding at an intermediate cooling temperature at least a portion of said first cooled fraction to the pressure of the mean pressure column in a turbine before introducing same into the double column; iv) boosting any remaining compressed air at the first high pressure to a second high pressure, said second high pressure being lower than at least one of (a) that pressure at which air condenses and (b) that pressure at which air pseudo-condenses, by heat exchange with oxygen vaporizing at the oxygen pressure of at least 13 bars, said second high pressure being at least equal to approximately 30 bars, and also, being selected so that one of air condensation and air pseudo-condensation at the second high pressure takes place at approximately the inlet temperature of the turbine; v) cooling and liquefying at least a portion of the boosted air, the flow rate of which is lower than the flow rate of liquid oxygen to be vaporized; vi) expanding said liquefied portion of air and introducing said expanded air into the double column; and vii) withdrawing at least one liquid product from the apparatus as a final product.

Claim 10

Process for the production of gaseous oxygen at a pressure of at least approximately 13 bars, by introducing air to be distilled in an apparatus provided with a double column comprising a low pressure column and a mean pressure column, said mean pressure column having a pressure, including pumping of liquid oxygen which is withdrawn at the bottom of the low pressure column, and vaporization of the pumped liquid oxygen compressed by heat exchange with air pressurized to a high pressure which is substantially higher than the pressure of the mean pressure column, wherein said process comprises the steps of: i) compressing all the air to be distilled to a first high pressure which is considerably higher than the pressure of the mean pressure column; ii) cooling a first fraction of the compressed air; iii) expanding at an intermediate cooling temperature at least a portion of said first cooled fraction to the pressure of the mean pressure column in a turbine before introducing same into the double column; iv) boosting any remaining compressed air at the first high pressure to a second high pressure, said second high pressure being lower than at least one of (a) that pressure at which air condenses and (b) that pressure at which air pseudo-condenses, by heat exchange with oxygen vaporizing at the oxygen pressure of at least 13 bars, said second high pressure being at least equal to approximately 30 bars, and also, being selected so that one of air condensation and air pseudo-condensation at the second high pressure takes place at approximately the inlet temperature of the turbine; v) cooling and liquefying at least a portion of the boosted air, the flow rate of which is lower than the flow rate of liquid oxygen to be vaporized; vi) expanding said liquefied portion of air and introducing said expanded air into the double column; and vii) withdrawing at least one liquid product from the apparatus as a final product.

Claim 11

Process according to claim 8, wherein in step iv) said second high pressure is achieved by means of a blower having a compression rate lower than 2.

Claim 12

Process according to claims 9, wherein the blower is operated by means of an outside source of energy.

Claim 13

Process according to claim 8, wherein said second high pressure is achieved by means of first and second blowers mounted in series and each connected to a respective expansion turbine, each said turbine having a respective inlet temperature, the first blower being connected to a first said turbine for expanding air at the first high pressure and the second blower being connected to a second said turbine for expanding a portion of the boosted air, the inlet temperature of the second turbine being higher than that of the first turbine.

Claim 14

Process according to claim 11, comprising withdrawing a quantity of air between said first and second blowers, and at least in part cooling and liquefying said withdrawn air and, after expansion introducing said air into the double column.

Claim 15

Process according to claim 8, wherein said second high pressure is achieved by means of a blower connected to the turbine for expanding air to the first high pressure, a first portion of the boosted air being expanded in a second turbine connected to a second blower which is fed with any remaining boosted air, the air originating from the second blower being cooled and liquefied and, after expansion, being introduced into the double column.

Claim 16

Process according to claim 13, wherein the air from the second blower is again boosted by means of the third blower which is operated by means of an outside source of energy.

Claim 17

Process according to claim 14, wherein a portion of the gaseous phase of the air issued from at least one turbine is expanded at low pressure in an additional turbine, and is thereafter blown into the low pressure column.