Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/32—Packing elements in the form of grids or built-up elements for forming a unit or module inside the apparatus for mass or heat transfer
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
  • F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
  • F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
  • F25J3/04763—Start-up or control of the process; Details of the apparatus used
  • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
  • F25J3/04896—Details of columns, e.g. internals, inlet/outlet devices
  • F25J3/04909—Structured packings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
  • F25J3/04763—Start-up or control of the process; Details of the apparatus used
  • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
  • F25J3/04896—Details of columns, e.g. internals, inlet/outlet devices
  • F25J3/04915—Combinations of different material exchange elements, e.g. within different columns
  • F25J3/04921—Combinations of different material exchange elements, e.g. within different columns within the same column
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/32—Details relating to packing elements in the form of grids or built-up elements for forming a unit of module inside the apparatus for mass or heat transfer
  • B01J2219/322—Basic shape of the elements
  • B01J2219/32203—Sheets
  • B01J2219/3221—Corrugated sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/32—Details relating to packing elements in the form of grids or built-up elements for forming a unit of module inside the apparatus for mass or heat transfer
  • B01J2219/322—Basic shape of the elements
  • B01J2219/32203—Sheets
  • B01J2219/32213—Plurality of essentially parallel sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/32—Details relating to packing elements in the form of grids or built-up elements for forming a unit of module inside the apparatus for mass or heat transfer
  • B01J2219/322—Basic shape of the elements
  • B01J2219/32203—Sheets
  • B01J2219/32224—Sheets characterised by the orientation of the sheet
  • B01J2219/32234—Inclined orientation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/32—Details relating to packing elements in the form of grids or built-up elements for forming a unit of module inside the apparatus for mass or heat transfer
  • B01J2219/322—Basic shape of the elements
  • B01J2219/32203—Sheets
  • B01J2219/32265—Sheets characterised by the orientation of blocks of sheets
  • B01J2219/32272—Sheets characterised by the orientation of blocks of sheets relating to blocks in superimposed layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/32—Details relating to packing elements in the form of grids or built-up elements for forming a unit of module inside the apparatus for mass or heat transfer
  • B01J2219/324—Composition or microstructure of the elements
  • B01J2219/32408—Metal

Definitions

• the present invention relates to a packed column for the exchange of heat and / or material between a descending liquid and a rising gas, of the type comprising at least one exchange section comprising several superposed sections of packings, or defined between two liquid distributors is defined between an inlet or a fluid outlet and a liquid distributor or between a first fluid inlet or outlet and a second fluid inlet or outlet or comprising at least 2 packing modules and at most 20 packing modules superposed, preferably directly on each other, this exchange section comprising a lower section and, above it, another section. It applies in particular to air distillation columns.
• packing is understood here to mean a device intended for putting in intimate contact a descending liquid and a rising gas, so that an exchange of heat and / or material takes place.
• the lining sections each consist of at least one packing module or "pack".
• These modules can be of the bulk type, that is to say each consisting of a volume of discrete particles, but are preferably of a so-called structured type. In this category in particular appear:
• Cross-corrugated packings generally constituted by corrugated strips comprising parallel alternating corrugations each arranged in a generally vertical plane and against each other, the corrugations being oblique and descending in opposite directions of a strip at the next.
• a perforation rate typically about 10% is generally provided for these so-called cross-corrugated packings.
• GB-AI 004 046 discloses cross-corrugated packings, and CA-AI 095 827 proposes an improvement of this type of packing by adding a small diameter dense perforation to allow the liquid to pass on either side crossed wavy bands.
• Such packing is generally made from a flat product, namely metal sheets in the form of strips.
• the strips are first folded (or bent) so as to form a kind of strip corrugated sheet whose corrugations are oblique with respect to the axis of the strip.
• the folded strips are then cut into sections and then stacked by alternately turning every other strip, so as to form modules or "packs".
• Fan packings each of which includes a plurality of baffles which define a set of horizontal layers of fixed upstream gas stirring fans.
• fan packings are structures having a three-dimensional effect on the gas that rises in the column. They ensure, by multiple rotation of the gas, a high turbulence of the gas, and the resulting stirring improves the exchange of heat and / or material with the descending liquid.
• the subject of the invention is a packing column of the aforementioned type, characterized in that the lower packing section of at least one section exchange comprises at least one packing module which has a number of transfer units less than that of at least one packing module of the other packing section of the same exchange section.
• NUTs vapor transfer units
• the number of vapor transfer units (NUTs) of a packing module is the quotient of the module height (HM) by the height of a transfer unit in phase steam (HUT).
• HUT is commonly used to characterize the intrinsic efficiency of a packing, it is connected to the height equivalent to a theoretical plate (HEPT) of this packing by the relation:
• HEPT HUT mVIL - 1 ln (m.VIL) where L: molar flow rate of liquid (mol / s) V: molar flow rate of steam (mol / s) m: slope of the equilibrium line in a digraph representing the fraction molar in the vapor as a function of the molar fraction in the liquid.
• the HUT and therefore the NUT of a packing module, depends moderately on the distilled fluids and the distillation conditions.
• the NUTs of two packing modules are compared, it will be understood each time that these two modules are placed under identical distillation conditions.
• this text will refer to the number of vapor phase transfer units: number of transfer units.
• the packed column according to the invention may comprise one or more of the following characteristics, taken separately or in any technically possible combination: said module of said lower section differs from said module of said other section of the same exchange section by at least one of the following factors:
• said factor is the average density, and said lower section occupies only a fraction of the cross section of the column, located under the jets of liquid from the section above it;
• said sections of packing are sections of structured packing; said lower packing section is a cross-corrugated packing section, while the other packing section is a fan packing section; said lower packing section is a relatively low density cross-corrugated packing section, while the other packing section is a higher density cross-corrugated packing section, the packing modules being angularly offset, in particular 90 ° relative to each other around the vertical central axis of the column; said lower packing section consists of a single packing module;
• said single module has a lower height than the modules of the other section of the same exchange section; in each exchange section, the packing modules are stacked on top of one another directly or with the interposition of spacer elements;
• the column is the low pressure column of a double air distillation column or a separation column of an argon enriched air gas mixture;
• the column comprises at least two sections one above the other of which at least the upper section has a lower section comprising at least one packing module which has a number of transfer units less than that of at least one packing module of the other packing section of the same exchange section and a space defined between the two sections, this space containing neither distributor nor fluid inlet from the outside.
• the two sections, one above the other each comprise at least 2 modules, preferably at least 4 modules, or even at least 5 modules.
• the section is between an inlet or a fluid outlet and a liquid distributor, the section possibly comprising at least 2 sections and at most 20 superimposed sections, preferably directly on one another,
• the section is between a first fluid inlet or outlet and a second fluid inlet or outlet, the section optionally comprising at least 2 sections and at most 20 superimposed sections, preferably directly on each other.
• the column operates at a pressure of less than 2 bar abs and / or constitutes the low column pressure of a double column or an argon separation column fed by an argon enriched air gas flow.
• Figure 1 shows schematically in axial section a double air distillation column according to the invention
• Figure 2 is a graph showing the variation. of loss of load and height per transfer unit for columns according to the prior art and a column according to the invention.
• the double air distillation column 1 shown in the drawing has a conventional structure with the exception of the constitution of its packings. It thus consists of a medium pressure column 2 surmounted by a low pressure column 3.
• a main vaporizer-condenser V puts the overhead vapor of the column 2 (almost pure nitrogen) in heat exchange relation with the vessel fluid (approximately pure oxygen) from column 3.
• Column 2 has a head liquid distributor 4 and, beneath it, a single air distillation section 5.
• Column 3 comprises: a head liquid distributor 6; an upper distillation section 9 located between the distributor 6 and the feed 12; an intermediate distillation section 10 comprising at least 2 modules and at most 20 modules below section 9; and a lower distillation section 11 comprising a minimum of 2 modules and a maximum of 20 modules located between the section 10 and the withdrawal 21.
• a distributor 7 separates the sections 9 and 10.
• “Poor liquid” at the top of the column 2 consisting of liquid nitrogen, is withdrawn via a line 14, expanded at low pressure in an expansion valve 15 and introduced into the distributor 6.
• the excess of condensed liquid nitrogen in the vaporizer-condenser V falls into the distributor 4, which distributes it on the distillation section 5.
• the incoming air rises and exchanges heat and material with the liquid nitrogen reflux in s gradually depleting oxygen.
• the rising gas is gaseous oxygen, which exchanges heat and material with the reflux liquid.
• the distributor 6 distributes liquid nitrogen on the distillation section 9.
• Each liquid distributor 4, 6, 7 comprises a peripheral trough 16 and several parallel U-shaped troughs 17 which open at each end into the trough 16. Between troughs 16 are defined parallel channels 18 for the passage of the upstream gas, closed by a horizontal upper wall 19. Just below this wall are formed rows of windows 20. The bottom of the troughs 17 is perforated, which defines a large number of vertical jets of liquid under each of these chutes.
• the double column 1 also comprises at least one product outlet such as a conduit 21 for withdrawing gaseous oxygen from the tank of column 2, situated just below section 11, and a pipe 22 for withdrawing gas. wastewater (impure nitrogen) from the top of column 3.
• the column 2 inlet air pipe is indicated at 23. It may comprise an air inlet 25 and / or distributors between the sections 10 and 11 and / or below the section HA.
• Each of the distillation sections 5, 9, 10, 11 consists of a stack of structured packing modules.
• the lower module constitutes the lower section 9A, 10A, HA of the section, while the other modules form the current section of the section.
• the modules are stacked either directly on one another or with the interposition of spacer elements.
• Each lower section 9A, 1OA, HA of the low pressure column 3 is constituted by a packing module or "pack" more particularly adapted to distribute uniformly over the entire cross section of the column the gas it receives from below, while the modules of each other section are more particularly adapted to perform a heat exchange of high efficiency material between the liquid and the rising gas.
• the lower section 9A may be of the same nature as the other section 9B but have an intrinsic density
• the lower section 10A may be of a different nature from that of the other section 10B, namely less effective from the point of view of distillation and less expensive.
• the lower section may be of the cross-corrugated type, in particular at low density or at an angle of inclination of the channels relative to the larger horizontal, whereas the current section 10B is denser or at an angle of inclination. weaker channels.
• the lower section HA can be a packing module whose height is lower than that of the modules of the upper sections HB. In this way, the height of the column is reduced without substantially penalizing the overall efficiency of the distillation, since the upper section is not fully effective.
• the lower section may consist of more than one packing module.
• the sections 9A, 10A and HA may be replaced by another section whose number of transfer units is reduced by modifying the section in another way described in this description.
• the lower section has, for each of its modules, a number of transfer units less than that of each module of the other section.
• case (2) By definition, the lower distillation efficiency corresponds to a smaller number of transfer units. At a constant density, the lining angle of inclination of the channels with respect to the larger horizontal has a reduced number of transfer units.
• case (3) Reducing the height of a module reduces its number of transfer units.
• the upper section of the distillation section of the column medium pressure 2 is a single cross-corrugated packing module according to EP-A-1186843.
• the upper section 5A of section 5 is discontinuous. It consists of several parallel strips, each of which is located below a corresponding chute 17 of the distributor 4.
• the other section 5B is a common section consisting of a stack of corrugated-crisscross packing modules. The modules of section 5 are angularly offset by 90 ° relative to each other around the X-X axis.
• the section HB of the section 11 is a current section consisting of a stack of corrugated-crimped packing modules whose density is greater than that of the lower section HA.
• the modules of section 11 are angularly offset by 90 ° relative to each other about the X-X axis.
• the HB section fulfills the role of distributor so that no distributor is required between sections 10 and 11.
• the lower portion 10A of section 10 is a common section consisting of a stack of fan-type packing modules. These modules are angularly offset by 90 ° relative to each other around the X-X axis.
• the section 9B of section 9 is a current section consisting of a stack of cross-corrugated packing modules of the same density as that of the lower section 9A, but of greater height than this one.
• the modules of section 11 are also angularly offset by 90 ° relative to each other about the axis XX. It is also conceivable that the upper section of a section has a number of transfer units lower or higher than that of a section of the section other than the lower section.
• the upper section may differ from the other section other than the lower section of the same exchange section by at least one of the following factors:
• each exchange section is composed only of sections having the same number of transfer units, the test sections 1 having a number of transfer units greater than the number for the Test 2 sections.
• Test 3 corresponding to the invention, all the sections of column section except the inner section have a number of transfer units identical to that for the test sections 1. The section smaller than a number of transfer units less than that of the sections greater than, equal to the number of transfer units found for Test 2 sections.
• the height per transfer unit is substantially the same for the packed column according to the invention (Test 3) and the column according to the prior art Test 1. On the other hand, a higher height is observed for the column of Test 2.
• the pressure drops are always of the order of 10% lower than those of the Test column 1, regardless of the congestion rate, resulting in significant energy savings.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Separation By Low-Temperature Treatments (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

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• 2008
  • 2008-04-07 FR FR0852300A patent/FR2929532B1/fr not_active Expired - Fee Related
• 2009
  • 2009-04-07 CN CN2009801117607A patent/CN101980775A/zh active Pending
  • 2009-04-07 US US12/935,929 patent/US9108179B2/en not_active Expired - Fee Related
  • 2009-04-07 EP EP09742259A patent/EP2265368A2/fr not_active Withdrawn
  • 2009-04-07 WO PCT/FR2009/050596 patent/WO2009136061A2/fr active Application Filing

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