Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/24—Cleaning or pickling metallic material with solutions or molten salts with neutral solutions
  • C23G1/26—Cleaning or pickling metallic material with solutions or molten salts with neutral solutions using inhibitors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto
  • B08B9/08—Cleaning containers, e.g. tanks
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/16—Organic compounds
  • C11D3/18—Hydrocarbons
  • C11D3/188—Terpenes
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/24—Cleaning or pickling metallic material with solutions or molten salts with neutral solutions
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
  • C11D1/02—Anionic compounds
  • C11D1/12—Sulfonic acids or sulfuric acid esters; Salts thereof
  • C11D1/22—Sulfonic acids or sulfuric acid esters; Salts thereof derived from aromatic compounds
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
  • C11D1/38—Cationic compounds
  • C11D1/52—Carboxylic amides, alkylolamides or imides or their condensation products with alkylene oxides
  • C11D1/523—Carboxylic alkylolamides, or dialkylolamides, or hydroxycarboxylic amides (R1-CO-NR2R3), where R1, R2 or R3 contain one hydroxy group per alkyl group
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
  • C11D1/66—Non-ionic compounds
  • C11D1/72—Ethers of polyoxyalkylene glycols
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
  • C11D2111/10—Objects to be cleaned
  • C11D2111/14—Hard surfaces
  • C11D2111/20—Industrial or commercial equipment, e.g. reactors, tubes or engines

Definitions

• This invention relates to the cleaning of process equipment and vessels to remove contaminants, particularly benzene, during turn-around periods making it safe for personnel to enter the vessel for maintenance and repair. Specifically, it involves an improvement in the process for using steam acids alkalies or wetting agents to decontaminate the vessels.
• an operating process vessel cannot merely be shut down and drained before entry of maintenance and repair crews.
• the vessel must first be rendered safe and decontaminated of any residual material in it which may be harmful, even fatal, to the workers who must enter to inspect and maintain, if not refurbish, the internal structure of the vessel.
• the present practice depending upon the vessel, is to inject steam for a period of time until monitoring devices indicate that no dangerous gases remain which present an explosive hazard to workers who must work in this environment.
• Vessels are also washed with water to remove contaminants where applicable, and often, both steaming and water washing is involved in the degassing of a vessel to make it possible for humans to safely enter to inspect and repair.
• Hazardous contamination of process vessels may also come from auxiliary pieces of equipment which are attached in fluid communication such as, for example, various kinds of heat exchangers and demister pads.
• This problem has been made much more difficult in view of the present concern that the hazardous materials removed from the vessel being cleaned become an environmental problem, either through release to the atmosphere or through improper disposal of wash water containing the waste.
• the previous attempts at steaming were just that, attempts, and often required long periods of time, days even, before the "sniffers" indicated the contaminant had been either removed or reduced to such a minuscule presence that the vessel was safe for entry. Water washing results in an inordinate amount of liquid waste for which disposal must be accomplished.
• US-A-2 023 496 relates to one prior method in which a heated liquid solution of a dissolving agent and an emulsifying agent are placed in contact with the surface to be cleaned. Steam may be used to atomize the solution.
• the goal of the present invention is to provide a process for vessel decontamination which exceeds this standard -- in fact, which approaches, if not meets, 0 ppm of benzene. Benzene can be trapped beneath scale or other contaminants only to seep out at a later time when cleaning had been considered completed or gathered in the head space of the vessel.
• the present invention provides a process for decontaminating a process vessel to remove hazardous chemical contamination, characterized by the steps of contacting contaminated surfaces of the process vessel with a heated aqueous solution containing a terpene extractant and a surfactant having an emulsification activity between the contaminant and water, agitating the solution in contact with the surface to allow invasion of interstices of scale residue on the surface by the surfactant and extractant for a time sufficient to entrap contaminants into the solution, and separating the solution from the surface to remove the contaminants from the vessel with the solution.
• the extractant material is chosen based upon its boiling point and vapor pressure and the known solubility of the contaminant in the extractant. Even if the surfactant and extractant do not boil in the temperature range of steam, if the partial pressure of these two components is sufficiently high at cleaning conditions, the material will be dispersed throughout the vessel and will condense in the interstices of the metal and matrix of hydrocarbon scale to assure extraction and removal of the contaminants, especially benzene. Condensation of the vapors in the closed vessel creates sufficient vacuum to extract the contaminants from the interstices and break down the scale particle. In the event other gases are present, such as, for example, hydrogen sulfide, a scavenger material for the hydrogen sulfide would also be used, such as, for example, an alkanolamine.
• the vessel to be decontaminated is a distillation tower, either with trays or packing, or similarly fitted reactors
• a cascading method is used to produce agitation of the solution against the contaminated surfaces, as opposed to the flowing condensed liquids mentioned above, to clean the tower where a pool of water is circulated from the bottom of the tower and discharged back into the top.
• the pool of liquid flows through the tower cascading down over the trays or through the packing, contacting the surfaces of the tower with extractant, surfactant and water mixture.
• the pool of liquid is recycled through the circulation loop at an optimum flow rate based upon the tower design for flooding the trays or tower packing. The skilled engineer can easily determine such rates for a given tower.
• a circulation rate from of about 3028 to 5299 lit/min (800 to about 1400 gallons per minute) is used, preferably about 3785 lit/min (1000 GPM) with simultaneous injection of steam to the base of the vessel to heat the circulating water.
• steam condenses on the internals in the tower as well as heating the water.
• the extractant and surfactant materials are injected into the water circulation loop or in the steam injection stream, or both.
• Circulation, with steam injection, is continued from about two to about eight hours, preferably from about four to about six hours, at a preferred temperature of about 85 0 C (185 0 F).
• the circulation is stopped and the tower is rinsed with fresh water and tested for unsafe contamination.
• Auxiliary equipment such as heat exchangers and tube bundles are also decontaminated by circulation of the hot water, extractant, and surfactant system of the invention.
• the vessels are all normally equipped with attachments where steam at a temperature of from about 100°C to 191°C (212°F to about 375°F), preferably from about 101°C to 177°C (215°F to about 350°F), may be introduced for periods of time to condense on the internal surfaces within the vessel and apparatus to wash it to the bottom where the contaminant and wash fluid is removed. Additional washing is often necessary with water and surfactants to gather up residual contaminants. It is this process of steam decontamination that is improved by the process of this invention. This improvement is brought about by introducing with the steam used to clean the tower a fog of an extractant, preferably accompanied by a surfactant.
• the extractant can be introduced into the tower with the steam or fogged into the vessel where it is then vaporized in the steam and carried up into the vessel where it condenses along with the steam and trickles down the inside of the vessel, agitating the solution against the contaminant while flooding the internals and thus removing the contamination.
• the extractant may be introduced into the steam and injected into a packed tower or a trayed tower while water is being circulated over the tower.
• Yet another alternative is to collect water in the bottom of the tower and circulate it over the tower while injecting steam to heat the circulating water to a temperature of from about 71°C to 110°C (160°F to about 230°F), preferably from about 85°C to 99°C (185°F to about 210°F), and then adding the extractant to the circulating water to obtain a concentration of from about 1-1/2% to about 5% by volume.
• the terpene extractant is chosen to correspond to the contaminant being removed.
• the criteria for selection are the solubility of the material being removed in the extractant, the vapor pressure and the boiling point of the extractant such that it is within the range of the temperature of the steam and will condense on the surfaces of the metal and in the interstices in the metal, preferably prior to the condensation of the steam, such that the water condensate, as it trickles down, washes the internal surfaces of the vessel.
• satisfactory extractants would include materials such as limonene and other like materials, preferably the various terpenes including for example dipentenes, cinenes, cajeputenes, diamylenes, the oils of bergamot, geranium, citronella, dill, and caraway, and the like and related terpenes such as hermiterpenes (isoprenes), sesquiterpenes (caryophyllenes), diterpenes, and polyterpenes.
• materials such as limonene and other like materials, preferably the various terpenes including for example dipentenes, cinenes, cajeputenes, diamylenes, the oils of bergamot, geranium, citronella, dill, and caraway, and the like and related terpenes such as hermiterpenes (isoprenes), sesquiterpenes (caryophyllenes), diterpenes, and polyterpenes.
• the extractant material should be non-toxic and non-hazardous and selected such that it has a high vapor pressure or boiling point within the range of the steam available at the particular plant for use, when injection with the steam is to be practiced, preferably within the range of from about 100 0 C to 191 0 C (212 0 F to about 375 0 F), preferably from about 135 0 C to 177 0 C (275 0 F to about 350 0 F).
• the partial pressure of the extractant will be significant at cleaning conditions.
• Mixtures of several extractants may be used satisfactorily with the same criteria as set forth above. Simple experimentation is all that is necessary to select the mixture and relative proportions.
• the matter of selecting the satisfactory surfactant is also within the range of one skilled in the art.
• the boiling point and vapor pressure criteria remain the same, i.e., up to about 191°C (375°F) such that the surfactant will also condense at substantially the same time as the steam and the extractant material condenses. This allows the cracks and crevices of the metal and tower internals, including the matrix of scaley contamination, to all be invaded by the components of this cleaning system to break down the scale and trap the contaminants into the solution (microemulsion) and remove the troublesome contaminants, especially benzene.
• the selected surfactants may be anionic, cationic, amphoteric or non-ionic, or mixture from several classes, but the selection specifically is within the experience of the skilled chemist, based upon the material being removed as the contaminant, the extractant being used and the relative amounts which are expected to be taken up into the wash from the condensing steam or subsequent water wash of the vessel, which, in the practice of this invention, should be substantially diminished over previous washing operations.
• the HLB (Hydrophile/Lyophile Balance) of the surfactants selected should be between 6 and 18 and preferably, between about 7.5 and 12 for the optimum results in the practice of this invention.
• the characteristics of the members of these classes of surfactants are well known as are the many compounds within these classes.
• the extractant per gram (pound) of steam should be introduced.
• the surfactant should be introduced in the ratio of from about 0.001 gr to 0.01 gr (0.001 pounds to about 0.01 pounds), preferably from about 0.003 gr to 0.005 gr (0.003 pounds to about 0.005 pounds), per gram (pound) of steam.
• both the extractant and surfactant are present, they are present in a ratio of from about 0.5 to 30 gr (0.5 to about 30 pounds) preferably from about 1.5 to 10 gr (1.5 to about 10 pounds), of extractant per gram (pound) of surfactant.
• all of the materials may be introduced simultaneously with the steam or any one introduced with the steam with either other or both of the extractant and surfactant being picked up by the steam within the tower, vaporized and transported up the vessel with the steam until condensed.
• the steam and extractant can be premised prior to injection into the vessel or injected at separate points in the vessel.
• the extractant, surfactant and steam, all three may be premixed prior to injection into the vessel.
• Many vessels notably catalytic cracking units and distillation columns, include reflux systems and demister pads of woven strands of metal at the upper end of the tower, which must also be decontaminated.
• the entire tower By carrying the extractant/surfactant steam mixture of this invention upwards through the vessel with condensation occurring at or near the top and even in the reflux equipment itself, the entire tower can be contacted and flushed through the practice of this invention, leaving only the liquid residue at the bottom of the tower for removal.
• the steam is injected into the vessel until a pressure of from about 2.9 to 8.7 kPa (20 to about 60 psig) is reached. Injection is stopped and the tower is held to allow condensation to occur on the internal surfaces.
• a cascading, or circulation, method is used to clean the vessel.
• the closed vessel usually a packed tower or trayed distillation column is first partially filled with water sufficient to wet packing or fill trays and still leave the pump intake covered when circulating, usually about 8% to 15% of the tower volume.
• a water circulation loop is provided by connecting a line from the bottom of the vessel to the top of the vessel. This loop allows the water to flow down through the packing or over trays in the vessel, be suctioned from the bottom, and pumped upward for discharge again to the top of the vessel.
• the water is recycled through the circulation loop at a rate sufficient to flood packing or fill the trays, preferably about 3185 lit./min (1000 GPM), with simultaneous injection of steam to the base of the vessel.
• the vessels are free from volatile organic compounds (VOCs), especially benzene which is known carcinogen.
• VOCs volatile organic compounds
• workmen could detect benzene by smell after a period of time spent working in the vessel.
• the VOCs would collect in the head space of the vessel where they could later be purged to the atmosphere. That purging is no longer possible under present environmental standards.
• the benzene odor never reoccurred and testing of a tower or other equipment with instruments indicated undetectable levels of benzene or other VOCs without purging the dangerous materials to the atmosphere.
• a preferred mixture of extractants and surfactants for cleaning a reaction vessel was prepared using the following components: (Mixture A) Weight Percent D. Limonene 57% Pluronic 10R-5 9% Monamulse 653-C 17% Butyl Cellusolve 3% Macon 10 5% Water 9% 100%
• microemulsion having a long shelf life and exhibiting good solvency for oils or greases, including the lighter materials such as benzene, toluene, and xylene which are trapped and held by the microemulsion until removed from the vessel in spite of the elevated temperatures at which the cleaning is performed.
• either microemulsion described above is injected with steam into the tower at a rate of 0.5 Kg per 1.4 to 1.8 Kg (1 pound per 3 to 4 pounds) of steam. The injection is continued until the tower is cleaned, the amount of surfactant/extractant and steam being determined by the size of the tower and the degree of contamination in it.
• This example describes decontamination cf a naphtha splitter tower to allow entry for maintenance on the tower internals. Excess liquid hydrocarbon was first flushed from the tower with fire hydrant water. The tower was then filled to 10% volume with water.
• a filter/pump trailer was connected to the tower, taking suction from the bottoms removal line of the tower, and discharging to the top tray of the tower, to provide a continuous, recycled cascade effect through the tower.
• Circulation of the water was commenced at 3185 lit/min (1000 GPM) to cause agitation between the solution and surface with simultaneous steam injection at the base of the tower using steam available at the refinery.
• 85°C 85°C
• the decontamination mixture of the present invention (Mixture B, above) was injected into the water loop to provide 2.0% concentration. Circulation was continued for 3-1/2 hours, while holding the temperature at 85 0 C (185 0 F).
• the circulation was then stopped and the liquid containing hydrocarbon scale and contaminants was pumped directly to refinery "slops" storage.
• the tower was rinsed twice with water and again all contaminated water was pumped to the slops.
• the tower was refilled to 10% volume with water, the cleaning Mixture B was again added to provide a 2.0% solution, and the circulation stage was repeated for 3-1/2 hours. As before, all "spent" solution and rinse water was pumped to slops.
• Decontamination was performed on a Visbreaker Tower which was 1.7m (5'6") in diameter and 19m (62') high, containing 23 trays with bubble cap design. Approximately 10598 lit (2800 gallons) (25% of tower volume) of water at 82 0 C (180 0 F) containing 3.0% of cleaning Mixture B was circulated for 8 hours through the whole tower using a filter truck connected to the tower as described in Example 1 above. Samples of the circulating water were collected at 1 hour intervals, to test how well the emulsification of the contaminants in the tower was progressing. After 8 hours, the spent solution from the tower was removed and hauled to a portable tank by a vacuum truck.
• the tower was then rinsed with fresh water and the rinsed water was also carried away to the portable tank by a vacuum truck.
• a tower manway was opened immediately upon completion of the rinse cycle.
• the tower was inspected and it appeared to be clean to bare metal. Inside tower walls, upon touching, felt grease-free and hydrocarbon-free. The next morning, refinery personnel inspected the tower and declared it safe for entry. There was neither odor of any hydrocarbon present nor detectable amounts by instruments.
• This example describes cleaning a heat exchanger bundle which had Visbreaker bottoms on the shell side and crude oil on the tube side.
• a 8.2m x 2.2m x 2.9m (27' x 8' x 9.6') "vat" was built and fitted with steam and air lines to clean the bundle.
• This is an auxiliary heat exchanger to the Visbreaker tower described in Example 2.
• the "vat” was filled with approximately 30280 lit (8000 gallons) of water. Steam was injected into the water via a steam line until the water temperature reached about 82 0 C (180 0 F). Four drums of cleaning Mixture B were added to the "vat" to make approximately 3% solution.
• the bundle had a heavy coat of viscous tar and coke on the shell side. In some places, the build up was about 7.6 cm to 10.2 cm (3" to 4") thick.
• the pulled bundle was then placed in the "vat" containing hot 3% aqueous solution described above.
• the "vat” was covered with a tarpaulin (to avoid atmospheric pollution) and an air line was connected to the vat and turned on to provide agitation. Foaming occurred and the air line was turned off.
• the bundle was soaked in the vat without agitation for 8 hours. After 8 hours, the bundle was taken to the hydroblast pad for hydroblasting with high pressure water.
• the bundle was soaked again for 4 hours in a fresh 3% solution of cleaning Mixture B.
• the second soaking of the bundle helped greatly because the cleaning mixture solution could now penetrate the scale, break down the hydrocarbon matrix and emulsify the tar between the tubes.
• Subsequent hydroblasting helped remove the previously impervious coke layer. It took approximately 1-1/2 to 2 days to clean the bundle, which normally takes up to 8 days. Refinery personnel were pleased with the results.
• the liquid circulation tubes of two finned fan coolers were connected in series and the volume of the tubes was calculated to be about 7570 lit (2000 gallons).
• a holding tank (Baker) was filled with approximately 11355 lit (3000 gallons) of water and a steam line was hooked up to the tank.
• the water in the tank was heated to 82 0 C (180 0 F) and approximately 303 lit (1-1/2 drums) (about 80 gallons) of the cleaning Mixture B was added to the tank.
• the solution thus made (about 2.75% of the cleaning mixture) was circulated through the tubes of the in fans connected in series for 6 hours at a temperature of about 82 0 C (180 0 F).
• the solution was drained back into the tank after circulation.
• Fresh water from a fire hydrant was used to rinse the fin fans. Discharge ports of the fin fans were inspected and looked very clean. Again, the refinery personnel were very pleased with the job. Two additional fin fans were cleaned on a later date, in the same manner, with excellent results. No hydrocarbon fouling was observed.
• This example relates to a successful decontamination of a complete hydrocracker process system at a refinery.
• the hydrocracker process system which was decontaminated consisted of the following ten units plus all the heat exchangers and piping associated with the units:
• Each of the above units were decontaminated following applicable steps of the previous examples using 1.0% of cleaning Mixture B, which was circulated for about 6 to 8 hours at 82°C (180°F). The units were then drained and rinsed with fresh water. The spent solution and rinse water were sent to a holding tank where it was disposed of with other refinery waste water.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Mechanical Engineering (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Wood Science & Technology (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Life Sciences & Earth Sciences (AREA)
• Cleaning By Liquid Or Steam (AREA)
• Cleaning In General (AREA)
• Wrappers (AREA)
• Containers Having Bodies Formed In One Piece (AREA)
• Packages (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Detergent Compositions (AREA)
• Food Preservation Except Freezing, Refrigeration, And Drying (AREA)

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• 1993
  • 1993-03-17 AT AT93104356T patent/ATE186756T1/de not_active IP Right Cessation
  • 1993-03-17 SG SG1996009473A patent/SG59993A1/en unknown
  • 1993-03-17 EP EP93104356A patent/EP0604698B1/en not_active Expired - Lifetime
  • 1993-03-17 PT PT93104356T patent/PT604698E/pt unknown
  • 1993-03-17 DK DK93104356T patent/DK0604698T3/da active
  • 1993-03-17 DE DE69327034T patent/DE69327034T2/de not_active Expired - Lifetime
  • 1993-04-16 CA CA002094165A patent/CA2094165C/en not_active Expired - Lifetime
• 1994
  • 1994-06-28 CN CN94107939.2A patent/CN1114243A/zh active Pending

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