Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
  • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
  • B01D53/047—Pressure swing adsorption
  • B01D53/0476—Vacuum pressure swing adsorption
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
  • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
  • B01D53/047—Pressure swing adsorption
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
  • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
  • B01D53/0407—Constructional details of adsorbing systems
  • B01D53/0446—Means for feeding or distributing gases
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
  • C01B13/02—Preparation of oxygen
  • C01B13/0229—Purification or separation processes
  • C01B13/0248—Physical processing only
  • C01B13/0259—Physical processing only by adsorption on solids
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/04—Purification or separation of nitrogen
  • C01B21/0405—Purification or separation processes
  • C01B21/0433—Physical processing only
  • C01B21/045—Physical processing only by adsorption in solids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/10—Inorganic adsorbents
  • B01D2253/106—Silica or silicates
  • B01D2253/108—Zeolites
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2256/00—Main component in the product gas stream after treatment
  • B01D2256/10—Nitrogen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2256/00—Main component in the product gas stream after treatment
  • B01D2256/12—Oxygen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/10—Single element gases other than halogens
  • B01D2257/102—Nitrogen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/10—Single element gases other than halogens
  • B01D2257/104—Oxygen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2259/00—Type of treatment
  • B01D2259/40—Further details for adsorption processes and devices
  • B01D2259/402—Further details for adsorption processes and devices using two beds
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0043—Impurity removed
  • C01B2210/0045—Oxygen
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0043—Impurity removed
  • C01B2210/0046—Nitrogen

Definitions

• the present invention relates to an improved method for separating oxygen or nitrogen from air in the sense of vacuum swing adsorption
• VSA vacuum-vacuum swing adsorption
• PVSA pressure-vacuum swing adsorption
• the preferred adsorption of nitrogen over oxygen is used, ie nitrogen in the air is adsorbed on the zeolite, the less strongly adsorbed components such as oxygen and argon are collected as a product when air flows through a zeolite bed at the outlet of this bed.
• the desorption of the adsorbed nitrogen can e.g. by evacuating the fill. In this case one speaks of the VSA process
• step a) is carried out at a pressure of 200 to 600 kPa and step b) is carried out at about 100 kPa with purging with part of the O 2 product (the pressures always relate to absolute values)
• Vacuum pumps previously used for vacuum desorption are two- or three-stage rotary lobe blowers with displacement function (see EP 158 262) or water ring pumps, also based on a
• centrifugal compressors that are used as vacuum pumps (see, for example, EP 575 591).
• These compressors known as radial blowers, have the property that they are operated up to a pressure ratio of back pressure to suction pressure of about 2.6 can, but for their optimal use, that is, to achieve the lowest possible energy requirement, a certain ratio between suction pressure and discharge pressure is required.This is also known as the optimal pressure ratio ⁇ .
• This pressure ratio ⁇ is around 1 6 to 1 7 with conventional radial blowers a radial blower is to be optimally used as a vacuum pump and the back pressure including the pressure loss of the downstream S chal 1 steam is equal to 1000 hPa, then a constant pressure of 625 or 588 hPa had to be set on the suction side.
• the evacuation pressure within about a minute e from a highest level (P Des-) ), typically 950 hPa to a lowest value (Pn c -m ⁇ n ), e.g. 300 hPa, the use of only one radial blower as a single stage is not possible considering the optimal low energy input
• the invention relates to a method for separating oxygen or
• ⁇ is brought to at least 0.6 times the ambient pressure, then in a desorption phase the adsorber containing the nitrogen or oxygen-coated adsorbent within a certain desorption time, in particular from 20 to 120 seconds, for the desorption of the adsorbed nitrogen or oxygen by means of the vacuum pump level of the higher pressure P l:) es.
• the positive displacement pump connected in series pump the adsorber, the positive displacement pump being connected to the pressure side of the radial blower, and that during the series operation of the radial fan and the positive displacement pump, the positive displacement pump running to the pressure side is set or dimensioned such that the radial blower is on average during the evacuation phase optimal
• the possible changeover of the pump arrangement from parallel to row is preferably carried out at an evacuation pressure P Dc 0 upstream of the radial fan, in particular when the evacuation pressure P Dcs 0 is at least the value formed from the pressure P () at the outlet of the pressure-side displacement pump divided by 0 65 * reached ⁇
• Radial blowers and positive displacement pumps are preferably operated in series at the beginning of the evacuation phase
• a preferred variant of the method according to the invention is characterized in that the pressure P cs . 0 in which the switch is made from parallel operation to series operation, is at least equal to the pressure P () at the outlet of the pressure-side displacement pump divided by 1.15 times the pressure ratio ⁇ of the radial fan
• a particularly advantageous variant of the invention is characterized in that for a given initial evacuation pressure P Des . ] at the beginning of the desorption phase, the minimum evacuation pressure P Des m
• the changeover of the pump arrangement from parallel operation to series operation can be controlled, for example, via a control system of the adsorption system according to a time specification or a pressure specification
• the downstream vacuum pump has to operate according to the displacement principle at a pumping pressure below 0 25 of the ambient pressure, it can consist of two or three displacement pumps connected in series
• FIG. 3 shows the characteristic curve and the pressure-dependent power consumption of a pumping station made up of radial blowers and rotary lobe blowers connected in series
• FIG. 5 shows the diagram of a VSA system for carrying out the method according to the invention
• the VSA system has the following components
• the adsorbers A, B and C are filled with Ca zeolite A granules with a grain size of 1 to 2.5 mm, which is produced according to Example 2 from the published patent application EP-A 0 170 026.
• the nitrogen adsorption on these granules is 1000 hPa and 25 ° C 14 Nl / kg the oxygen adsorption 4.3 Nl / kg
• the nominal diameter of the adsorbent was 1 000 mm, the height of the rubble of the total fill was 2200 mm.
• a 20 cm layer of silica gel was attached to the inlet of the adsorber.
• the height of the rubble of the zeolite granules was 200 cm, the weight of the zeolite was 1 000 kg
• the adsorbers A, B, C are operated in cycles.
• valve 15 A on adsorber A is open. Only valves I2C and 13C are open on adsorber C. Sucked in by pumping station V10, O - rich gas flows from adsorber A via valve 15A, open control valve 17 ABC and valve 13C in adsorber C The pressure in adsorber A thus drops from the adsorption pressure to a lower pressure P D s , (relaxation phase) In adsorber C, the evacuation is ended, the pressure in adsorber C falling from the final pressure increases to a higher pressure
• Adsorber B begins with the air separation (adsorption phase), that is, ambient air passes through valve I IB into adsorber B, 0 -, - real product gas leaves the adsorber via valve 14B and is discharged with compressor G10 to the product supply (not shown)
• Valve 15A on adsorber A is closed again and only valve 12A is open.
• adsorber A becomes pressurized by P es. , sucked to the pressure Po e - mm with the vacuum pump VI 0.
• the adsorber B is in the adsorption phase, ie the valves I IB and 15B are open.
• the valves 18 ABC, 16ABC and 13C open the adsorber C with O 2 -re ⁇ chem Gas filled
• valve 13C Only valve 13C is open on adsorber C The full quantity is dimensioned so that at the end of this period the pressure in adsorber C almost reaches the adsorption pressure (covering phase) In the next cycle of the cycle, adsorber C separates the air (adsorption phase), in the third cycle of the cycle adsorber A, ie the two cycle times of 0-8 sec and 8-60 sec are repeated accordingly
• the maximum adsorption pressure was always 1 100 hPa, the minimum evacuation pressure P ]) CS-mm was always 300 hPa.
• the pressure P cs was compared, at the beginning of the evacuation step. In the first variant, this starting pressure was 950 hPa and compared to it 800 hPa was the pressure at the outlet of the pump stand (P 0 & ambient pressure including the strau pressure of the muffler behind the pump stand) was on average 1050 hPa
• Capacity at 300 hPa was about 1,000 m 3 / h
• the characteristic curve of a two-stage rotary blower is shown in FIG. 2.
• the second stage connected in series, has a 40% lower suction power at ambient pressure than the first stage on the suction side, depending on the gradation ratio. Between 1,000 hPa and 200 hPa, the suction power of the overall characteristic curve drops by about 10%. from
• the evacuation pressure P Dc is achieved in that the valve 12C is closed in the above-mentioned time cycle of "0-8 sec", ie a pressure equalization or a partial pressure equalization between adsorber A and C takes place during this time evacuates the vacuum pump
• the evacuation pressure P Dcs- ⁇ is achieved in that in the above-mentioned time cycle of "0 - 8 sec" on adsorber C only valve 12C is open, thereby adsorber C is evacuated to its final pressure.
• Adsorber B is only Valve I IB opened, causing the air blower C10 to
• the optimum starting pressure P es] for evacuation with a connected vacuum pump level is achieved relatively quickly by only using adsorber C in the time interval of "0 - 8 sec.” 98/01215. ,,.
• valves 1 IB and 14B are open on adsorber B, whereby the air blower CIO fills the adsorber B with air and already produces O -, - rich gas.
• the valves 12A and 15A are open fills the adsorber C via valves 15A, 17ABC and 13C.
• the pressure in adsorber A drops rapidly to the desired optimal starting pressure P D - I re ' at ' v due to the vacuum pump VI 0 connected to valve 12A
• Figure 6 gives the measured pressure curve at a starting pressure P I c;>. ] from 950 hPa again
• the pumping station E) (series connection of radial blowers with rotary lobe compressors) with its low suction capacity at higher pressures has a relatively high pressure level in the suction process compared to type D (two-stage rotary lobe blowers)
• the pumping station F (start with parallel operation of the radial blower and rotary lobe compressor) with its higher suction capacity at higher pressures has a relatively low pressure level in the extraction process compared to type D (two-stage rotary lobe blower), which suggests an unfavorable energy requirement
• FIG. 7 shows the measured pressure curve at a starting pressure P Dcs.) Of 800 mbar. Compared to FIG. 6, the evacuation characteristics are not so far apart
• the ambient pressure would be 1000 hPa and 50 hPa dynamic pressure

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• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Separation Of Gases By Adsorption (AREA)
• Oxygen, Ozone, And Oxides In General (AREA)

Applications Claiming Priority (3)

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• 1996
  • 1996-07-08 DE DE19627422A patent/DE19627422A1/de not_active Withdrawn
• 1997
  • 1997-07-01 CZ CZ9940A patent/CZ4099A3/cs unknown
  • 1997-07-01 EP EP97929311A patent/EP0910457A1/de not_active Withdrawn
  • 1997-07-01 CA CA002259660A patent/CA2259660A1/en not_active Abandoned
  • 1997-07-01 WO PCT/EP1997/003434 patent/WO1998001215A1/de not_active Ceased
  • 1997-07-01 JP JP10504728A patent/JP2000513997A/ja active Pending
  • 1997-07-01 PL PL97331017A patent/PL331017A1/xx unknown
  • 1997-07-01 BR BR9710225A patent/BR9710225A/pt unknown
  • 1997-07-07 TW TW086109661A patent/TW380118B/zh active
  • 1997-07-07 ZA ZA9706025A patent/ZA976025B/xx unknown
• 1999
  • 1999-01-07 KR KR1019997000051A patent/KR20000023604A/ko not_active Withdrawn

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