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
  • C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
  • C25B15/087—Recycling of electrolyte to electrochemical cell
• • 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
  • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
  • C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
  • C25B11/036—Bipolar 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
  • C25B15/00—Operating or servicing cells
  • C25B15/02—Process control or regulation
• • 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
  • C25B9/13—Single electrolytic cells with circulation of an electrolyte
• • 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
  • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
  • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms

Definitions

• the invention relates to an electrochemical half cell, which consists at least of a membrane, an optionally gas-developing electrode ' or anode
• Cathode optionally an outlet for the gas and a support structure which connects the optionally gas-developing electrode with the half-cell rear wall.
• the support structure divides the interior of the half-cell into vertically arranged channels, the electrolyte flowing upward in the electrode channels facing the electrode and flowing downward in the channels facing away from the electrode, and the electrode channels and the channels facing away from the electrode at their upper and lower End connected.
• Another problem is to operate the electrolysis cell with the most homogeneous vertical and horizontal temperature and concentration distribution (salt concentration or pH value of the electrolyte) in the area of the electrolyte space in front of the membrane surface, also to avoid premature membrane aging.
• This is generally desirable for the operation of all gas-developing electrolysers, but in particular for the use of gas diffusion electrodes in which the heat dissipation (dissipation of the lost heat) is predominant or complete must take place via the electrolyte circuit on the other, gas-generating side, depending on whether work is being carried out beyond the membrane with a finite electrolyte gap (finite gap) or with an overlying gas diffusion electrode. This may result in a lowering of the temperature of the inflowing fresh electrolyte for the gas-generating side, which must not lead to local overcooling here.
• the invention relates to an electrochemical half-cell consisting at least of a membrane, an optionally gas-developing electrode as an anode or cathode, and a support structure which connects the optionally gas-developing electrode to the half-cell rear wall, and an inlet for the electrolyte and an outlet for the electrolyte and optionally for the gas, characterized in that the support structure divides the interior of the half cell into vertically arranged channels, the electrolyte in that of the electrode facing electrode channels flows upward and flows downward in the channels facing away from the electrode and that the electrode channels and the channels facing away from the electrode are connected to each other at their upper and lower ends.
• the channels with downward flow and the electrode channels are arranged alternately next to one another or else one behind the other.
• the channels with downward flow and the electrode channels can have a trapezoidal cross section.
• the channels with downward flow and the electrode channels are preferably formed by a folded, electrically conductive sheet metal as the supporting structure.
• the electrode channels have a cross-sectional constriction at their upper end.
• a vertically aligned parallel support structure separates the channels open to the electrode, in which the lighter electrolyte-gas mixture rises, from channels open to the rear wall, in which the degassed, heavier electrolyte flows down again.
• Essential for the improvement of the gas separation is a constriction at the top of the electrolyte channels, which is generated by a wing-like flow deflection profile that is bent towards the electrode. The two-phase flow is accelerated in the constriction between the electrode and the profile, above the backward curved upper edge of the
• the cross-sectional area of the electrode channels in the narrowest region of the constriction in relation to the cross-sectional area of the electrode channels below the constriction is preferably from 1 to 2.5 to 1 to 4.5.
• the narrowing of the electrode channels can be formed, for example, by an angled guide structure.
• the narrowing of the electrode channels has in particular an area with a constant cross section, the height of this area being at most 1:
• the half-cell can be produced in a particularly simplified manner if the guide structure is formed in one piece with the support structure.
• Electrode channels have an expansion of their cross section above the constriction.
• the excess electrolyte leaving the cell can be discharged behind the flow deflection profile either laterally at the top or downwards via a vertical standpipe.
• Electrolytes and the gas possibly formed during the electrolysis in particular a standpipe with passage in the cell bottom or one on a side wall of the Cell arranged outlet, which is arranged just above the upper end of the electrode channels.
• the overall structure - apart from the connection openings at the bottom and the few mm wide connection gap above the profile at the top - consists of a functional unit in order to fulfill the following functions:
• the carrying structure takes on the function of mechanically holding the electrode and, moreover, the function of connecting the electrode to the cell rear wall with low resistance.
• the support structure with the electrode channels and the outflow channels fills the interior of the half cell to at least 90%.
• the support structure is preferably electrically conductive and is electrically conductively connected to the electrode and in particular to the rear wall of the half cell.
• the electrode is then preferably connected in an electrically conductive manner to the support structure of the half cell and fastened on the support structure.
• a heat exchanger is preferably connected upstream of the inlet of the electrolyte, through which fresh electrolyte and, if appropriate, degassed electrolyte returned from the outlet is introduced into the half-cell, so that a temperature-controlling electrolyte circuit is formed, if necessary.
• the electrolyte converted in the anode chamber is, for example, an aqueous sodium chloride solution or a hydrochloric acid solution and chlorine is obtained as the anode gas.
• the counter electrode is an oxygen consumption cathode.
• the amount of electrolyte fed into the cell increases compared to the internal circulation, so that the latter has to be particularly intensive in order to avoid even a local skew. This applies in particular to a highly desirable strong acidification of the brine in the case of NaCl electrolysis, which normally has to be based on the lowest local pH value.
• the half-cell is operated with a finite catholyte gap (finite gap) in front of an oxygen consumption cathode, part of the heat loss can be dissipated on the cathode side through the flow through this catholyte gap and external cooling, while the majority of the heat loss is dissipated with the anolyte flow
• the half cell is operated with an oxygen consumption cathode (zero gap) resting on the membrane, the entire heat loss is dissipated via the anolyte stream.
• the half cell according to the invention can generally be used in all gas-developing electrolyses. It is of particular importance in electrolysis, where electrolyte and gas are more difficult to separate.
• FIG. 1 shows a schematic cross section through a half cell according to the invention without a power supply line according to line B-B 'in FIG. 3
• FIG. 2 shows a schematic longitudinal section through a half-cell according to the invention along the line A-A 'in FIG. 3
• Fig. 3 The front view of the half-cell according to the invention with the electrode removed
• a flow and day structure 12 is welded in an electrically conductive manner in a half cell 1 (FIG. 1). It carries the electrode structure 3, on which in turn the membrane 4 either rests or is positioned at a smaller distance from the electrode structure 3.
• the support structure 12 is constructed from trapezoidal-shaped sheets which form vertical channels which are alternately open to the electrodes or are directed to the rear wall 15 as outflow channels 5.
• the fresh electrolyte 17 flows through an inlet pipe 10 and through openings 11 into the half-cell interior 13, the openings 11 being distributed such that they supply each of the channels 9 open to the electrode with fresh electrolyte.
• the openings 11 can also be arranged under the outflow channels 5 in order to improve mixing between the fresh electrolyte and the electrolyte flowing out in the outflow channels 5 (see FIG. 2).
• the gas evolution at the electrode 3 leads to a buoyancy of the electrolyte in the channels 9 open to the electrode.
• the alternation between acceleration and relaxation achieves a very effective bubble separation, so that the electrolyte and electrode gas have already been largely separated on the back of the profile structure.
• the profile structure 2 only protrudes into the upflow channels 9, but is open in the direction of the outflow channels 5.
• the degassed, heavier electrolyte can flow downward in the outflow channels 5, mix with the fresh electrolyte flowing in at the bottom, and convert the electrode structure again into an upward flow, so that there is an intensive natural convection (see FIG. 3).
• the excess electrolyte 18 leaves the half-cell 1 together with the gas separated behind the profile 2 either via a standpipe 8, as shown in FIGS. 1 and 3, or alternatively via a side outlet 16, as in FIG. 2 and in FIG. 3 is drawn.
• the following variants can also be used with comparable success (cf. FIG. 4).
• the gas-developing electrodes 3 be they anodes or cathodes
• flow guidance structures in semicircular form 28 with the bubble inflow region 20 and the outflow region 21 can be between these structural elements.
• the separating element 26 can also penetrate the structural elements 29 in a suitable manner as a continuous plate and extend over the entire width of the element. But it can also prove to be advantageous if this
• Separating elements are inserted individually between the structural elements 29 before the electrodes 3 are welded in and fix the separating elements.
• the separating elements 26, 27, 28 have no electrical function, they can be made not only of metal but also of non-conductive form from suitable plastic molded parts which have suitable chemical stability and temperature resistance. be performed. Depending on the application, EPDF is available here; Halar or Telene on.
• the bent-back part 6 of the profile 2 leaves an 8 mm gap to the upper edge of the half cell 1 for the passage of the two-phase flow to the rear (see FIG. 2).
• the passage openings to the downward channels 5 are open for an unimpeded outflow of the degassed electrolyte 14.
• the excess anolyte brine is taken up via a standpipe 8, which ends somewhat below the upper edge of the profile 2, and discharged downward from the cell 1.
• oxygen cathodes are used in the finite gap mode with a catholyte gap of 3 mm.
• Cell can be operated free of pressure pulsations. It was found that the half cells in the working area between 3 and 7 kA / m 2 with complete separation can be operated by gas and electrolyte, ie the running anolyte was completely free of bubbles and ran completely evenly and without any palpable or visible pulsation.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Metallurgy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Automation & Control Theory (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
• Electrodes For Compound Or Non-Metal Manufacture (AREA)
• Hybrid Cells (AREA)

Priority Applications (11)

Applications Claiming Priority (2)

Publications (1)

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Citations (5)

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• 1998
  • 1998-10-30 DE DE19850071A patent/DE19850071A1/de not_active Withdrawn
• 1999
  • 1999-10-20 PT PT99953890T patent/PT1133587E/pt unknown
  • 1999-10-20 KR KR1020017005402A patent/KR100607632B1/ko not_active Expired - Fee Related
  • 1999-10-20 JP JP2000579809A patent/JP2002528648A/ja active Pending
  • 1999-10-20 CZ CZ20011503A patent/CZ20011503A3/cs unknown
  • 1999-10-20 HU HU0104430A patent/HUP0104430A3/hu unknown
  • 1999-10-20 WO PCT/EP1999/007949 patent/WO2000026442A1/de not_active Ceased
  • 1999-10-20 AT AT99953890T patent/ATE257868T1/de not_active IP Right Cessation
  • 1999-10-20 BR BR9914956-7A patent/BR9914956A/pt not_active Application Discontinuation
  • 1999-10-20 CN CNB998125954A patent/CN1208501C/zh not_active Expired - Fee Related
  • 1999-10-20 ES ES99953890T patent/ES2211188T3/es not_active Expired - Lifetime
  • 1999-10-20 US US09/830,492 patent/US6596136B1/en not_active Expired - Lifetime
  • 1999-10-20 AU AU10411/00A patent/AU763013B2/en not_active Ceased
  • 1999-10-20 PL PL99347424A patent/PL190638B1/pl not_active IP Right Cessation
  • 1999-10-20 EP EP99953890A patent/EP1133587B1/de not_active Expired - Lifetime
  • 1999-10-20 CA CA002348394A patent/CA2348394A1/en not_active Abandoned
  • 1999-10-20 DE DE59908322T patent/DE59908322D1/de not_active Expired - Lifetime
  • 1999-10-20 ID IDW00200100944A patent/ID29184A/id unknown
  • 1999-10-25 AR ARP990105381A patent/AR018966A1/es not_active Application Discontinuation
  • 1999-10-29 TW TW088118731A patent/TW466279B/zh not_active IP Right Cessation
• 2001
  • 2001-04-26 NO NO20012056A patent/NO20012056L/no not_active Application Discontinuation

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