EP4079938A1 - Ensemble cadre de cellule pour un électrolyseur, électrolyseur et son procédé de fabrication - Google Patents

Ensemble cadre de cellule pour un électrolyseur, électrolyseur et son procédé de fabrication Download PDF

Info

Publication number
EP4079938A1
EP4079938A1 EP21170110.7A EP21170110A EP4079938A1 EP 4079938 A1 EP4079938 A1 EP 4079938A1 EP 21170110 A EP21170110 A EP 21170110A EP 4079938 A1 EP4079938 A1 EP 4079938A1
Authority
EP
European Patent Office
Prior art keywords
cell frame
cell
electrolyzer
shell
staple
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP21170110.7A
Other languages
German (de)
English (en)
Inventor
Vicente FANDINO
Christian Haegele
Adrian Schneider
Hartmut Hähnle
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Zosen Innova AG
Original Assignee
Hitachi Zosen Innova AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Zosen Innova AG filed Critical Hitachi Zosen Innova AG
Priority to EP21170110.7A priority Critical patent/EP4079938A1/fr
Publication of EP4079938A1 publication Critical patent/EP4079938A1/fr
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/60—Constructional parts of cells
    • C25B9/63—Holders for electrodes; Positioning of the electrodes
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/70—Assemblies comprising two or more cells
    • C25B9/73—Assemblies comprising two or more cells of the filter-press type
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water

Definitions

  • the invention is related to a cell frame assembly for an electrolyzer, electrolyzer and method of manufacturing thereof.
  • Such cell frame assemblies respectively cell frames forming a cell frame assembly for an electrolyzer are known f.i. from DE 10 2014 010 813 A1 .
  • a frame structure of the cell frame has close to its outer border an embedded reinforcement ring to provide availability of such electrolysis cells also for electrolysis being performed under high pressure.
  • the reinforcing ring may be set into a mold for forming the cell frame and is, thereby, embedded therein. Then, the cells may be completed by adding the various membrane, bipolar pellets, sealings, and other parts to create, cell by cell, the cell stack being eventually sandwiched between end-plates of the electrolyzer to form the electrolyzer.
  • a cell frame assembly for an electrolzyer of the cell-stack type comprising a plurality of stacked individual inner cell frame parts and at least temporarily during manufacturing and/or mounting an integral outer reinforcing shell or an axial holding arrangement extending over a subset of at least two stacked inner cell frame parts.
  • a plurality (subset of at least two) (inner) cell frame parts are provided with an integral outer reinforcing shell, even a larger number of at least 3 or 4, at least 6, at least 8, or even more.
  • said outer shell can be provided in form of a wrapping.
  • the construction of the plurality of inner cell frame parts and outer shell is divided again to the level of single inner cell frame parts, f.i. by cutting.
  • Such cutting could be mechanical cutting, f.i. sawing or other techniques as laser cutting can be provided.
  • it is sufficient to cut only the outer shell, since the inner cell frame parts are axially not connected anyway.
  • manufacturing of reinforced cell frames becomes easier in the overall performance irrespective of the apparent double work to first combine and later separate the inner cell frame parts.
  • the mounting of the re-separated cell frames to form electrolyzer cells and forming the electrolyzer cell stack by such electrolyzer cells can be as usual in a one-by-one mounting process.
  • the mounting of the electrolyzer cells between the end-plates of the electrolyzer is not one-by-one, but by modules containing already a subset of at least two pre-mounted cells.
  • Such pre-mounting can be effected at a different location than the mounting location of the electrolyzer, advantageously shifting mounting time from the final mounting process to preparatory mounting processes which can be organized in advance and which allow also to have already mounted modules on hold. This enables also to increase the safety level for the final mounting process, involving a lower number of parts to be handled, in particular in consideration of the several sealings to be applied with high accuracy in the final mounting process according to the actually practiced mounting process in the art.
  • an axial holding arrangement can be provided to hold a subset of electrolysis cells axially together in the pre-mounting process.
  • the holding mechanism of the holding arrangement may comprise axial bars extending through manifolds in the cell frames later used for electrolyte transport. It is understood that such axial holding arrangement is for temporary mounting only and is removed prior to final mounting. Outer clamping brackets can be used, also.
  • the axial holding arrangement is provided by an outer shell as f.i. in form of a wrapping.
  • an outer shell as f.i. in form of a wrapping.
  • the cell frames as referenced above in another embodiment are combined for common wrapping, but a subset of at least two cells comprising already the remaining components such as membrane, sealings, bipolar plates are wrapped together.
  • Such wrapping can be either a temporary wrapping removed and used only for mounting purposes as the above-described axial holding arrangement in general. Otherwise, the wrapping remains and serves as integral outer reinforcing shell.
  • openings are made in the outer shell/the wrapping in order to allow passage of at least partly circumferential portions of the bipolar plates. This enables on the one hand side cell voltage measurements during operation of the electrolyzer.
  • the area of the bipolar plate accessible by passing through the openings in the shell is at least 6000 mm 2 , preferably at least 15,000 mm 2 , in particular at least 24,000 mm 2 .
  • the integral outer reinforcing shell provides for reinforcement against radial forces. Therefore, fixing between the outer shell and the inner cell frame against axial displacement is preferred for some embodiments, while not mandatory for other embodiments.
  • the above-described embodiments can be applied alone and/or in combination. For instance, a first number of stacked cells can have the same outer shell, and two or more of such sub-assemblies with respective common outer shell can be axially held within an axially holding arrangement.
  • mounting can be done without pre-mounted stacks held by axial holding arrangements, but a single outer reinforcement shell for an individual inner cell frame part can be result of a separation process of a previously common integral outer reinforcing shell applied in a common working (application) step to a subset/plurality of individual inner cell frame parts.
  • the invention can be applied for any kind of electrolyzer of the cell-stack type. Particularly preferred are electrolyzers for alkali electrolysis. In a preferred application of a method of operating the electrolyzer, electrolysis of water to produce hydrogen (and oxygen) is preferred.
  • the overall number of cells is at least 20, preferably at least 40, in particular at least 60.
  • the invention has advantages in particular also for even larger electrolyzers having at least 80, preferably at least 100, in particular at least 120 cells inbetween the end-plates of the electrolyzer.
  • the outer shell or holding arrangement extends over at least or exactly 3 or 4, preferably at least or exactly 5, even 6 or more of the inner cell frame parts. This provides handable modules regarding in particular their overall weight.
  • said plurality comprises all cells of a complete stack, and an outer reinforcement formed by one or more of said outer shells comprises not more than 60, preferably not more than 50, in particular not more than 40 integral outer shells.
  • the outer shell or axial/holding arrangement is detachably mounted to the inner cell frame parts. This allows better dismounting after end of temporary mounting state and/or for maintenance purposes.
  • the shell is in form of a wrapping.
  • a sheet material comprising or made of carbon fiber, glass fiber, and/or other materials as resin materials, f.i. PPS, PPE, PSU material can be wound over in particular cylindrically formed staples.
  • a bonding agent, f.i. a resin can be applied between the first winding and the outer surface of the inner cell frame parts and/or between the surfaces of subsequent windings of the wrapping.
  • the wrapping may comprise at least 2, preferably at least 4, in particular at least 6 full terms. This further increases resistance against radial forces arising due to the pressure in the process.
  • the integral outer shell may comprise reinforcement fibers, in particular carbon fibers and/or fibers in form of staple fibers.
  • the fibers are comprised in an amount of at least 6, preferably at least 12, in particular at least 24 weight% of the integral outer shell.
  • the fibers can be embedded in a resin material, f.i. those indicated above.
  • the invention also provides an electrolyzer of the cell-stack type, comprising a cell frame assembly according to any of the preceding aspects and/or manufactured according to any of the precedingly described aspects of manufacturing.
  • electrolyzers combine the advantages of reasonable resistances in particular against radial pressure forces on the one hand side with facilitated manufacturing and/or mounting on the other hand side.
  • the invention provides also a method of operating the electrolzyer, wherein the cell frame assembly is kept in a working state with the integral outer reinforcing cell frame part being mounted to the individual inner cell frame parts in a first state in which the electrolyzer performs electrolysis of a liquid, in particular produces hydrogen from water, wherein for maintenance the integral outer shell is removed from the individual inner cell frame parts in preparation for a second maintenance state in which access to the cells is given, and the integral outer reinforcing cell frame part is reapplied after maintenance.
  • the outer reinforcing shell is not only temporarily applied in the manufacturing process of the cell frames, but also kept after mounting and in particular acting as axial holding arrangement.
  • the shell can also be not removed but cut on a level of the individual inner cell frame parts such as to allow separation thereof.
  • the invention also provides a method of manufacturing such electrolyzer, comprising stacking a plurality of cell frame parts, thereby providing a cell frame staple, and mounting an integral outer reinforcing shell extending over a subset of at least two stack inner cell frame parts of the cell frame staple.
  • a method of manufacturing such electrolyzer comprising stacking a plurality of cell frame parts, thereby providing a cell frame staple, and mounting an integral outer reinforcing shell extending over a subset of at least two stack inner cell frame parts of the cell frame staple.
  • said mounting may comprise to apply the outer shell in form of a wrapping.
  • this also allows a setting of reinforcement level against radial forces by varying, in particular increasing the number of turns of the wrapping.
  • the invention provides a method of manufacturing the electrolyzer, comprising the steps of forming, at a first location, a cell staple of a plurality of cells and applying thereto a temporary axial holding arrangement axially holding the staple together, transporting said staple held by the holding arrangement to a second location where the staple is inserted between end-plates of the electrolyzer and where the holding arrangement is removed.
  • the invention provides a method for manufacturing cell frames to form a cell frame stack for an electrolyzer of the staple-type, comprising the steps of forming a number of cell frames corresponding to the number of cells of the electrolyzer, providing a subset of at least two of said cell frames with an outer reinforcement shell, in particular in form of a wrapping, separating the common outer shell such as to re-establish individual cell frames having each an individual outer reinforcement shell from the previous integral outer reinforcing shell, mounting the cell staple of the electrolyzer on the basis of said individual cell frames with individual outer shell, one-by-one or in form of pre-mounted modules comprising two or more cells.
  • Fig. 1 shows in an explosive view and without details the general structure of part of a cell stack assembly.
  • a pressure frame 30 holds a membrane 20 against a main frame 10, which has holes 12 being part of a manifold to provide the electrolyzer with electrolyte and to discharge the electrolyte.
  • a bipolar plate 40 is sandwiched between the cell frame 10 and subsequent cell frame 10.
  • the invention is by no means restricted to the type of electrolyzer, although an electrolyzer for water electrolysis to produce hydrogen (and oxygen) is preferred.
  • the electrolysis technique can be that of alkali electrolysis, PEM electrolysis, or other.
  • FIG. 2 main frame 10 of Fig. 1 is shown separately. Again, structural details as protrusions, recesses, positioning pins, channels for proper coupling to membrane, pressure frame, sealings, and so on, are omitted, as they are well known to the person skilled in the art.
  • the main frame 10 as shown in Fig. 2 could be manufactured by f.i. diecasting.
  • a plurality of such main frames 10 as shown in Fig. 2 are axially stapled to form an ensemble 100 of cell frame bodies axially adjacent one to another. In this state, each frame 10, the ensemble 100 is provided with an outer reinforcement 11.
  • the ensemble is rotatably held by holding arrangement 200.
  • a wrap of reinforcing material in form of a strap 310 is wound for a plurality of windings onto the circumferential outer surface of the ensemble 100.
  • a fixing liquid is applied to the last wound winding (and before winding the first winding), such that the continuously wound strap 310 rolled from a strap roll 300 is appropriately fixed.
  • the ensemble 100 of a plurality of cell frames 10 obtains each a reinforcement 11 (by its share of shell 110) together in one and the same manufacturing step.
  • the fixing agent may be applied by spraying via nozzle 400 or otherwise.
  • the machining step shown in Fig. 3 may be carried out semi-automatically or even manually.
  • the ensemble 100 comprising the plurality of cell frames 10 is shown with common reinforcement shell 110.
  • the common reinforcement shell 110 is cut by a suitable cutting arrangement 500 with cutter 501, as shown in Fig. 5 .
  • the ensemble 100 of the plurality of cell frames can be held again by holding arrangement 200.
  • the representation of Fig. 5 is a schematical representation, and various kinds of cutting techniques may be applied, such as the (shown) mechanical cutting, as well as other cutting techniques such as laser cutting.
  • Important for this exemplified embodiment is the separation of the reinforcing shell 110 in single reinforcings 11, one for each cell frame 10. At the end of the cutting step ( Fig.
  • a staple of cell frames 10 having each an outer reinforcement 11 comprising a plurality of windings of reinforcing strap fixed to each other by f.i. the resin applied during manufacturing of reinforcing shell 110 shown in Fig. 3 .
  • the single reinforced cell frames 10 can be separated from each other, thereby dismounting the ensemble to obtain reinforced cell frames 10, which can then be used to build up cells and a cell frame staple according to the structure shown in Fig. 1 .
  • formation of an ensemble of cells and formation of a common reinforcing shell for the ensemble can be created in a similar way as illustrated in Figs. 3 and 4 .
  • the ensemble is not only formed by cell frames 10, but already by a plurality of stacked cells 60.
  • access to the electrodes, in the present embodiment bipolar plates 40 need to be created, which could be, in one example, by drilling holes into the common reinforcing shell 110, to be able to contact bipolar plates 40.
  • bipolar plates are formed with radially extending pins 41, which radially extend beyond the outer diameter of the cell frames 10. This is shown in Fig. 7 , where an ensemble 160 of cells 60 is shown in axially stapled manner.
  • a plurality of circumferentially arranged and radially extending pins 41 are protruding radially outwards.
  • pins 41 can be and preferably are integral with bipolar plates 40.
  • bipolar plates 40 can be manufactured with a larger diameter than that of cell frame 10, and material can be removed to leave pins 41. This could be, f.i. done by mechanical cutting, laser cutting, or any other cutting technique as water jet cutting or other.
  • a lower number of pins 41 than shown can also be provided, f.i. when for the purpose of contacting for measuring the cell voltage. Also taps instead of or additionally to pins can be provided, for bridging purposes.
  • pins 41 penetrate strap 310 during its winding around the ensemble 160. Therefore, as shown in Fig. 8 , after formation of the common outer reinforcing shell 110 formed by a plurality of windings of reinforcing strap 310 and the fixing agent, the pins 41 still radially extend out of the reinforced ensemble 180, composed of 160, 110, and can be contacted for proper working, but give also the possibility to measure cell voltages, respectively to bridge a possibly defect cell.
  • this flexibility and different mounting approach can also be applied even in case that there is not the integral common reinforcing cell 110, due to the cutting step shown in Fig. 5 .
  • a sub-stack 190 of cells 60 is pre-mounted and held together by clamping means 290, as shown for an example in Fig. 9 , with four clamping brackets 290 axially holding the plurality, in the shown embodiment five cells 60 together.
  • the number of cells 60 held by clamping means 290 can be selected in particular also in dependency of the overall weight of one cell 60, such that for smaller electrolyzer with lower diameter, maybe more cells can be held together, while for larger diameter electrolyzer, the number may be appropriately selected and be lower. However, even when only two or three cells 60 are pre-mounted for a sub-stack 190, the mounting time for mounting the complete cell stack in the final mounting process can be significantly reduced.
  • bipolar plates 40 radially extend beyond the cell frames 10, similar as shown in Fig. 8 not in form of the pins 41 but with larger surface areas or even completely.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
EP21170110.7A 2021-04-23 2021-04-23 Ensemble cadre de cellule pour un électrolyseur, électrolyseur et son procédé de fabrication Withdrawn EP4079938A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP21170110.7A EP4079938A1 (fr) 2021-04-23 2021-04-23 Ensemble cadre de cellule pour un électrolyseur, électrolyseur et son procédé de fabrication

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP21170110.7A EP4079938A1 (fr) 2021-04-23 2021-04-23 Ensemble cadre de cellule pour un électrolyseur, électrolyseur et son procédé de fabrication

Publications (1)

Publication Number Publication Date
EP4079938A1 true EP4079938A1 (fr) 2022-10-26

Family

ID=75659888

Family Applications (1)

Application Number Title Priority Date Filing Date
EP21170110.7A Withdrawn EP4079938A1 (fr) 2021-04-23 2021-04-23 Ensemble cadre de cellule pour un électrolyseur, électrolyseur et son procédé de fabrication

Country Status (1)

Country Link
EP (1) EP4079938A1 (fr)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4615107A (en) * 1984-11-16 1986-10-07 Sanyo Electric Co., Ltd. Method and device for assembling a fuel cell stack
JPH02144857A (ja) * 1988-11-25 1990-06-04 Hitachi Ltd 燃料電池及びその分解方法
JPH0729592A (ja) * 1993-07-09 1995-01-31 Honda Motor Co Ltd 燃料電池用セルスタックおよびその組立方法
US5686200A (en) * 1993-12-22 1997-11-11 Ballard Power Systems Inc. Electrochemical fuel cell assembly with compliant compression mechanism
US20050069743A1 (en) * 2003-01-08 2005-03-31 Toshiro Kobayashi Stacked fuel cell and method for its maintenance
EP2434570A1 (fr) * 2010-09-22 2012-03-28 Siemens Aktiengesellschaft Batterie électrochimique et procédé d' échange de cellules d'une telle batterie
DE102014010813A1 (de) 2014-07-23 2016-01-28 Etogas Gmbh Rahmen für eine Elektrolysevorrichtung, Elektrolysezellen-Modul und Elektrolysevorrichtung

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4615107A (en) * 1984-11-16 1986-10-07 Sanyo Electric Co., Ltd. Method and device for assembling a fuel cell stack
JPH02144857A (ja) * 1988-11-25 1990-06-04 Hitachi Ltd 燃料電池及びその分解方法
JPH0729592A (ja) * 1993-07-09 1995-01-31 Honda Motor Co Ltd 燃料電池用セルスタックおよびその組立方法
US5686200A (en) * 1993-12-22 1997-11-11 Ballard Power Systems Inc. Electrochemical fuel cell assembly with compliant compression mechanism
US20050069743A1 (en) * 2003-01-08 2005-03-31 Toshiro Kobayashi Stacked fuel cell and method for its maintenance
EP2434570A1 (fr) * 2010-09-22 2012-03-28 Siemens Aktiengesellschaft Batterie électrochimique et procédé d' échange de cellules d'une telle batterie
DE102014010813A1 (de) 2014-07-23 2016-01-28 Etogas Gmbh Rahmen für eine Elektrolysevorrichtung, Elektrolysezellen-Modul und Elektrolysevorrichtung

Similar Documents

Publication Publication Date Title
JP4799866B2 (ja) 膜ベース電気化学電池スタック
US8232015B2 (en) One-shot fabrication of membrane based electrochemical cell stacks
US8123889B2 (en) Adhesion method and adhesion apparatus of separators, and separator adhesion body
JP4515233B2 (ja) 燃料電池とセル締結ピン
JP2010508628A (ja) 燃料電池を連続製造するための方法および装置
JP6759247B2 (ja) 燃料電池
DK2898115T3 (en) Electrolysis block as well as cell frame, electrode module and kit
WO2007096012A1 (fr) Ensemble electrode a membrane avec structure d'etancheite renforcee
EP4079938A1 (fr) Ensemble cadre de cellule pour un électrolyseur, électrolyseur et son procédé de fabrication
US20030221311A1 (en) Fuel cell assembly and sealing
DE102012202832B4 (de) Verfahren zur Herstellung einer Komponente für eine Wasserdampftransfereinheit sowie solch eine Wasserdampftransfereinheit
WO2003092096A2 (fr) Empilement de cellules electrochimiques a base de membrane
US20090197136A1 (en) High-Volume-Manufacture Fuel Cell Arrangement and Method for Production Thereof
WO2019048101A1 (fr) Procédé de fabrication d'un composite d'une plaque bipolaire et d'un assemblage électrode-membrane à l'aide d'une fixation magnétique
US20120052410A1 (en) High-Volume-Manufacture Fuel Cell Arrangement and Method for Production Thereof
JPH07249426A (ja) 燃料電池およびその製造方法ならびに燃料電池の収納ケース
US20050158601A1 (en) Method to startup a fuel cell stack without battery derived compressor power
WO2008079143A1 (fr) Couche hydrophobe pour une pile à combustible
WO2008050598B1 (fr) Cellule électrochimique
KR20210078380A (ko) 전극의 교대 공급에 의한 단위셀의 제조방법
EP3493307B1 (fr) Pile à combustible
JP2004134179A (ja) 燃料電池スタック及びその組立方法
EP4084162A1 (fr) Procédé de fabrication d'un ensemble membrane-électrode
US20230089216A1 (en) Insert for cell frame integrated with adhesive film and method of manufacturing cell frame using the same
JP2024502975A (ja) 燃料電池膜加湿器

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN PUBLISHED

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20230427