EP0484042B1 - Méthode pour enlever les boues et les dépôts à l'intérieur d'un réservoir d'échangeur de chaleur - Google Patents

Méthode pour enlever les boues et les dépôts à l'intérieur d'un réservoir d'échangeur de chaleur Download PDF

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Publication number
EP0484042B1
EP0484042B1 EP19910309816 EP91309816A EP0484042B1 EP 0484042 B1 EP0484042 B1 EP 0484042B1 EP 19910309816 EP19910309816 EP 19910309816 EP 91309816 A EP91309816 A EP 91309816A EP 0484042 B1 EP0484042 B1 EP 0484042B1
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Prior art keywords
deposits
liquid
sludge
removing sludge
heat exchanger
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EP19910309816
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German (de)
English (en)
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EP0484042A1 (fr
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Allen Jay Baum
William Edward King
Gregg Daniel Auld
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Westinghouse Electric Corp
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Westinghouse Electric Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/48—Devices or arrangements for removing water, minerals or sludge from boilers ; Arrangement of cleaning apparatus in boilers; Combinations thereof with boilers
    • F22B37/483—Devices or arrangements for removing water, minerals or sludge from boilers ; Arrangement of cleaning apparatus in boilers; Combinations thereof with boilers specially adapted for nuclear steam generators

Definitions

  • This invention generally relates to a method for removing sludge and deposits from the interior of a heat exchanger vessel and more particularly relates to a method for removing sludge and deposits from the secondary side of a nuclear steam generator.
  • Nuclear steam generators generally comprise a bowl-shaped primary side through which hot, radioactive water from the reactor core is circulated, a secondary side disposed on top of the primary side into which non-radioactive water is fed, and a tubesheet which includes a number of U-shaped heat exchanger tubes disposed between the primary and secondary sides of the generator for thermally connecting but hydraulically insulating the primary and secondary sides so that heat from the radioactively contaminated water in the primary side would be conducted to the non-radioactive water in the secondary side, thereby causing it to boil and to create non-radioactive steam.
  • the U-shaped heat exchanger tubes are contained within the secondary side of said steam generators. Each such heat exchanger tube in inverted, with its open ends mounted in the tubesheet and its legs and bent portion extending into the secondary side. A plurality of vertically spaced-apart support plates are provided in the secondary side for laterally supporting the legs of each heat exchanger tube.
  • the legs of the U-shaped heat exchanger tubes extend through bores present in the support plates. Small, annular spaces are present between these heat exchanger tubes and the bores in the support plates and tubesheet through which these tubes extend. These annular spaces are known in the art as "crevice regions".
  • crevice regions provide only a very limited flow path for the water that circulates within the steam generator, which in turn can cause the water entering these regions to boil completely away, thereby causing these regions to dry-out.
  • This chronic drying-out causes impurities in the water to plate out and collect in these crevice regions. These impurities may promote the formation of deposits and cause corrosion on the exterior surfaces of the tubes.
  • the resulting corrosion products and sludges can, over time, accumulate in the crevice to the point where they can actually dent the heat exchanger tubes.
  • heat exchanger tubes are made from corrosion-resistant Inconel® 600, if the resulting impurities and sludges are not removed, sufficient corrosion and stress can occur in the crevice region areas of these tubes to ultimately cause them to crack unless some sort of maintenance operation is undertaken. Since a cracked heat exchanger tube can cause radioactive fluids from the primary side to contaminate the non-radioactive water in the secondary side of the generator, it is important that maintenance operations be implemented to prevent such corrosion and subsequent cracking from occurring.
  • Pressure pulse cleaning provides a completely mechanical way to clean the interior of a steam generator.
  • the generator is taken off-line, drained, and then filled with demineralized water up to the top of the bundle of heat exchanger tubes that are disposed within the secondary side.
  • Pressurized pulses of gas are then continuously introduced into this demineralized water near the tubesheet of the generator as the generator is being filled.
  • These pulses of gas create shock waves in the demineralized water within the secondary side which tend to loosen, dislodge and even fluidize the sludge and deposits present on the heat exchanger tubes, the support plates, the tubesheet and in the crevice regions of the secondary side.
  • the dislodged and fluidized sludge and deposits are removed from the demineralized water by recirculating them through a filter during the pressure pulsing operation.
  • the pulses of pressurized gas responsible for the generation of the debris-removing shock waves are continuously introduced into the demineralized water not only during the recirculation step, but also during the time that the demineralized water is introduced into and drained from the secondary side.
  • pressure pulse cleaning induces no new, unwanted corrosion on the metallic surfaces within the secondary side of the steam generator, it represents a substantial advance in the art, and is rapidly gaining acceptance in the nuclear power industry as an alternative to chemical cleaning methods.
  • pressure pulse cleaning is capable of removing a great deal of the sludge and deposits present in many of the secondary sides of such steam generators, it is rarely effective in removing all of the tightly ensconced deposits that accumulate in the crevice regions of the generator.
  • one of the factors that limits the effectiveness of pressure pulse cleaning is that the intensity of the shock waves generated by the pluses of pressurized gas is curtailed by the limited hydraulic flow path presented by these regions.
  • Sludge lancing is often performed on the tubesheet regions prior to pressure pulsing to remove the large accumulations of sludge and deposits on top of the tubesheet. Sludge lancing is also performed after the pressure pulsing operation has been completed to remove loosened deposits that have fallen out of solution onto the tubesheet. Unfortunately, such sludge lancing adds to both the time and expense of the pressure pulsing cleaning operation.
  • EP-A-0 339 289 filed March 31, 1989 in the name of Westinghouse Electric Corporation.
  • This patent application discloses a method comprising the steps of providing a sufficient volume of a liquid, such as water, into the steam generator so that the lower portion which includes the tubesheet is submerged.
  • a succession of pressure pulses are then generated within the water from one or more pressure pulse generators.
  • Each pressure pulse creates shock waves that exert momentary forces throughout the submerged portion of the generator of a magnitude sufficient to loosen the sludge and debris, but safely below the yield and fatigue limits of the heat exchanger tubes and other components within the generator.
  • EP-A-0 339 289 does not disclose any type of chemical cleaning.
  • the invention resides in a method for removing sludge and deposits (32) from the interior of a heat exchanger vessel (1), including the steps of introducing a liquid into the interior of the vessel, and introducing a succession of pressurized pulses of gas into the liquid to generate shock waves that loosen and remove said sludge and deposits from said vessel interior, characterized in that said liquid includes a cleaning agent formed from a least one of the group consisting of surfactants, dispersants, thixotropes and flotation agents to promote fluidization and to inhibit re-setting of said sludge and deposits.
  • the aqueous solution is formed from a combination of surfactant to promote penetration of the of the solution into the crevice regions within the secondary side, and a dispersant to promote the fluidization of the loosened sludge and deposits.
  • the surfactant is preferably formed from at least one of the group consisting of Immunol 236 (a combination of alkylphenoy ethoxylate, ethylene oxide, and fatty alkanol amide), Surfynol 104 (tertiary acetylenicdiol), Triton-X100 (octyphenorypoly ethoxyethanal) and Hamposyl-L (lauroyl sarcosine), while the dispersant is formed from at least one of the group consisting of polyacrylates, acrylic polymers, polypropyloxy quarternium ammonium acetate, imidazoline acetate and aminedodecylbenzine sulfontate.
  • the concentration of the cleaning agents within the water component of the solution is preferably maintained to between about 0.1 and 0.5 weight percent.
  • the secondary side of the steam generator is filled with the aqueous solution of cleaning agent up to the top of the bundle of heat exchanger tubes which is contains.
  • the aqueous solution is then recirculated through a filtration system to remove sludge and deposits that have been dislodged and loosened by the shock wave generated by the pressurized pulses of gas that are continually introduced into the solution.
  • the solution is then drained out of the interior of the secondary side of the generator.
  • the introduction of the pressurized pulses of gas into the solution may commerce shortly after the solution is first introduced into the interior of the secondary side, and may further continue throughout the draining step.
  • the pressure of the gas used to create the pulses is increased from about 2.76 to 6.21 MPa as the secondary side is filled with the solution, and maintained at between about 5.52 and 6.21 MPa during the recirculation step, and then is reduced from about 6.21 to 2.76 MPa when the solution is drained from the interior of the secondary side.
  • the pressurized pulses are generated at a frequency of between about 10 and 60 seconds.
  • the draining step of the method may be halted when the level of the solution within the secondary side is about the same as the lowermost support plate, and the recirculation of the solution may be recommenced through the filter means while pulses of pressurized gas continue to be discharged into the solution until the density of the sludge and deposits entrained in the solution reaches a selected low level, whereupon the draining step is finally completed.
  • the solution is pumped at a flow rate of preferably over at least 94.64 litres per minute in order to help maintain the entrainment of sludge and deposits within the solution as it flows into the filter means.
  • the chemically enhanced pressure pulse cleaning method of the invention is more effective than pressure pulse cleaning methods alone and about as effective as chemical cleaning methods without inducing the unwanted corrosion associated with the cleaning agents used in prior art chemical cleaning methods. It further obviates the need for the post cleaning sludge lancing associated with prior art pressure pulse cleaning methods, and is faster and easier to implement than prior art chemical cleaning techniques since there is no need to heat the cleaning solutions, and further generates less in the way of radioactive liquid wastes since multiple baths of cleaning agent are unnecessary.
  • the enhanced pressure pulse cleaning method of the invention is particularly useful in cleaning the interior of a nuclear steam generator 1.
  • Such generators 1 include a bowl-shaped primary side 3 at their bottom portions, and a cylindrically shaped secondary side 5 in their middle portions which are hydraulically separated by means of a tubesheet 7. Heat is conducted from the primary side 3 to the secondary side 5 through a number of heat exchanger tubes 9, each of which is shaped like an inverted U.
  • Each tube 9 includes an inlet end 11 and an outlet end 12 which are mounted in bores in the tubesheet 7.
  • a divider plate 14 divides the bowl-shaped primary side 3 into two quadrispherical chambers known as channel heads 16a,b in the art.
  • a feed water inlet 20 is provided for admitting non-radioactive and purified water over the bundle of U-shaped heat exchanger tubes 9 so as to immerse the same.
  • a steam drying assembly 22 Disposed above these tubes 9 is a steam drying assembly 22 which captures and returns water vapor entrained in the steam created by the generator 1 back into the feed water that immerses the heat exchanger tubes 9.
  • An outlet port 24 at the top of the steam generator 1 conducts dry steam to the blades of a turbine that is connected to an electrical generator (not shown).
  • a number of vertically spaced support plates 26 are disposed along the length of the secondary side 5 of the steam generator 1 for laterally supporting the legs of the U-shaped heat exchanger tubes 9.
  • each of these support plates 26 includes a plurality of bores 28 through which the heat exchanger tubes 9 extend.
  • hot radioactive water from the reactor core (not shown) is admitted into the channel head 16a, and from thence flows upwardly into the inlet ends 11 of each of the heat exchanger tubes 9.
  • This hot water flows upwardly through the inlet legs of each of the tubes 9 (known as hot legs in the art), continues flowing around the bend of each of the tubes 9, and from there flows down through the outlet legs (known as cold legs) and from thence out through the outlet ends 12 of the heat exchanger tubes 9 and into the outlet channel head 16b, where it is ultimately recirculated back to the core of the reactor.
  • the hot, radioactive water from the primary side transfers much of its heat through the walls of the heat exchanger tubes 9 and into the non-radioactive water that surrounds these tubes 9. This causes the non-radioactive water to boil, and to create the steam which is ultimately conducted out of the outlet port 24 of the steam generator 1.
  • sludge and deposits 32 can completely fill the annular space 30.
  • the primary components of the sludge and deposits 32 include magnetite (Fe3O4), elemental copper, and copper oxide.
  • Such sludge and deposits can promote the occurrence of corrosion in the outer walls of the heat exchanger tubes 9 in the vicinity of the support plates 26, which in turn may cause these tubes 9 to crack, thereby contaminating the non-radioactive water of the secondary side 5 with the hot, radioactive water from the primary side 3 of the generator 1.
  • the same destructive phenomenon can also occur in the annular spaces (not shown) between the bores in the tubesheet 7, and the outer walls of the heat exchanger tubes 9 that extend through these bores.
  • One of the principal purposes of the enhanced pressure pulse cleaning method of the invention is to remove such sludge and deposits 32 from crevice regions such as the annular space 30, along with the products of any corrosion which this debris might have started.
  • the method of the invention involves the generation of pressure pulses in an aqueous solution of a surfactant, dispersant, thixotrope, and/or a flotation agent introduced into the secondary side 5 of the steam generator 1 in order to loosen, dislodge and fluidize such sludge and deposits 32.
  • Figures 1 and 3 illustrate the best mode of implementing the method of the invention, wherein both pressure pulse generators 33a,b and a solution recirculation system 34 are installed within the lower hand holds 35a,b and upper manways 37a,b of the nuclear steam generator 1. More specifically, a pressure generator 33a,b having a nozzle 41 for emitting a pressurized pulse of gas is detachably secured within each of the lower hand holes 35a,b. A source of pressurized gas 43, which may be a compressed bottle of nitrogen or air, is connected to each of the pressure pulse generators 33a,b, as is a pulser control unit 45 which periodically actuates the pulser generators 33a,b to discharge a volume of compressed nitrogen through the nozzle 41.
  • a source of pressurized gas 43 which may be a compressed bottle of nitrogen or air
  • each of the pressure pulse generators 33a,b includes a pulser control unit 45 which periodically actuates the pulser generators 33a,b to discharge a volume of compressed nitrogen through the nozzle 41.
  • each of the pressure pulse generators 33a,b is a PAR 600 B air gun manufactured by Bolt Technology Inc. located in Norwalk, Connecticut, U.S.A.
  • the pulser control unit 45 is a model FC100 controller manufactured by the same corporate entity.
  • nozzles 41 are schematically illustrated as being horizontally oriented, they are more preferably canted at a 30 angle with respect to the upper surface of the tubesheet 7 so as to minimize the momentary forces that the shock waves created by the pulses of gas apply to the heat exchanger tubes 9 nearest the open ends of the nozzle 41.
  • the firing cylinder of each of the pressure pulse generators 33a,b contains between 1229 and 1638 cubic cms. of pressurized gas.
  • the recirculation system 34 that is preferably used to implement the method of the invention includes a pair of suction conduits 48a,b which extend through the hand holes 35a,b, respectively.
  • a mounting plate (not shown) allows both the nozzles 41 of the pressure pulse generators 33a,b and the suction conduits 48a,b to be mounted in water-tight engagement over the hand holes 35a,b.
  • the open ends of these suction conduits 48a,b are each located in close proximity to the upper surface of the tubesheet 7.
  • each suction conduit 48a,b has an internal diameter of approximately 76.2 cm or more in order to easily conduct the preferred flow rate of cleaning solution out of the steam generator 1 of 946.4 litres per minute.
  • These conduits 48a,b may be formed from either a durable plastic such as polyvinylchloride, or stainless steel pipes.
  • both of the suction conduits 48a,b converge into a main re-circulation conduit 50.
  • Conduit 50 has an in-line strainer assembly 52 that is disposed upstream of the intake of suction pump 54.
  • the purpose of the strainer assembly 52 is to prevent large particles of sludge and other debris entrained in the solution exiting the steam generator 1 from damaging the blades of the suction pump 54, which is preferably an impeller-type pump having a capacity of about 1135.6 litres per minute.
  • a filtration system 56 Downstream of the suction pump 54 is a filtration system 56 for removing fine particles of sludge and deposits from the aqueous cleaning solution being re-circulated through the secondary side 5 of the steam generator 1.
  • This filtration system 56 has an upstream filter bank 58 formed from filter units 60a,b, and a downstream filter bank 62 formed from filter units 64a,b.
  • Each of the filter banks 58 and 62 are connected parallel with respect to one another so that one filter bank may be completely isolated from both the main conduit 50 and the other filter bank when it becomes necessary to change the filter elements in the units of either of the banks 58,62.
  • filter units 60a,b are bag-type filters
  • filter units 64a,b are cartridge-type filter units.
  • the filter elements (not shown) in each of the filter units 60a,b and 64a,b are each preferably sized to remove particulate matter having a diameter of one 0.001 mm or more.
  • a resin bed 74 Downstream of the filtration system 56 is a resin bed 74 which is formed from a plurality of ion-exchange columns hydraulically connected in parallel. As will be described more specifically hereinafter, the resin bed 74 does not normally come on-line until the cleaning operation has been completed, as the purpose of the bed 74 is to remove all of the chemical cleaning agents and other ionic species which are present in the aqueous solution exiting the generator 1 in order to convert it back to de-mineralized water.
  • Three isolation valves 76a,b,c are provided so that cleaning solution leaving the filtration system 56 may be forced through the resin bed 74 at the end of the cleaning operation.
  • An optional return conduit (illustrated in phantom) may be provided which connects the outlet of the resin bed 74 back to the main conduit 50.
  • Such an optional conduit is provided when it is desired to circulate the cleaning solution through the bed 74 to remove dissolved, radioactive ionic species from the solution. However, if this mode of operation is desired, it will be necessary to select resins for the ion-exchange columns that will not remove the dissolved cleaning agents present in the solution, but only the radioactive ionic species.
  • An isolation valve 77 is provided in the optional return conduit to isolate the flow of solution through the main conduit from any contact with the resin bed 74 when the bed 74 is not is use.
  • a holding tank 78 Downstream of the resin bed 74 is a holding tank 78.
  • the tank 78 has a capacity of about 1892.7 litres.
  • the purpose of the tank 78 is to insure that a sufficient amount of solution is present throughout the recirculation system 34 at all times to avoid the introduction of air either into the inlet of a solution-introduction pump 80 (located downstream of the tank 78), or in any other critical junction within the system 34.
  • the impeller-type solution introduction pump 80 is located downstream of the holding tank 78.
  • the purpose of this pump 80 is to drive the filtered cleaning solution through the balance of the main conduit 50 so that it is forceably discharged through the two inlet conduits 82a,b that are connected to the terminus of the conduit 50.
  • the outlet ends of the inlet conduits 82a,b are located just above the bundle of heat exchanger tubes 9.
  • the inlet conduits 82a,b effectively hose-down sludge and debris that would otherwise settle on the top surfaces of the support plates 26 so that this sludge and debris is ultimately entrained in cleaning solution flowing over the top surface of the tubesheet 7 which in turn is ultimately sucked up by the suction conduits 48a,b.
  • the technique of vertically recirculating a cleaning liquid throughout the secondary side 5 of a steam generator 1 is an inventive concept described and claimed in U.S. patent application serial number 07/456,436 filed December 26, 1989, the entire specification of which is expressly incorporated herein by reference.
  • an inlet valve 84 that is connected to an inlet conduit 86 joins with the main conduit 50 just upstream of the holding tank 78.
  • the purpose of the inlet conduit 86 is to introduce cleaning solution from a reservoir (not shown) connected to conduit 86.
  • the steam generator 1 is taken off-line, and all of the water in the secondary side 5 is then completely drained.
  • sludge lancing may or may not be necessary at this juncture. If the sludge and deposits on the tubesheet 7 and support plates 26 are relatively light (i.e., not thick), no sludge lancing is necessary and the recirculation system 34 illustrated in Figure 3 is then hydraulically connected to the secondary side. If, however, these deposits are several centimeters thick, sludge lancing in accordance with known prior art techniques is carried out for two reasons.
  • such sludge lancing expedites the entire cleaning operation by quickly removing what might amount to up to 453.6 Kg of sludge and debris that, while loosely deposited on the tubesheet 7 and other areas of the generator 1, would tend to hydraulically insulate crevice regions such as the annular spaces 30 between the bores 28 in the support plates 26 and the heat exchanger tubes 9 from the penetrating and cleaning action of any surrounding cleaning agent.
  • such sludge lancing reduces the number of times that the various filter units 60a,b and 64a,b of the filtration system 56 must be back-washed or changed during the pressure pulse cleaning phase of the method.
  • the next step of the method is to install the mounting plates (not shown) which secure the nozzles 41 of the pressure pulse generators 33a,b and the suction conduits 48a,b the hand holes 35a,b, and to further install the inlet conduits 82,b through the upper manways 37a,b into position over the bundle of heat exchanger tubes 9.
  • inlet valve 84 is opened to admit a flow of cleaning solution into the holding tank 78 from a reservoir (not shown).
  • the solution introduction pump 80 is actuated to spray this solution through the inlet conduits 82 over the heat exchanger tubes 9 to begin to fill the secondary side 5 with solution.
  • the cleaning solution is an aqueous solution of de-mineralized water containing a surfactant, a dispersant, a thixotrope, and/or a flotation agent.
  • concentration of the cleaning agent within the de-mineralized water is preferably no more than 0.5 weight percent, and may be as little as 0.1 percent.
  • the surfactants, dispersants, thixotropes and flotation agents forming the active ingredients within the cleaning solution are selected so as to be substantially free from either sodiumchloride, or sulfate ions which can render the cleaning solution either undesirably alkaline or acidic.
  • These cleaning agents are further selected so as to be substantially free from phosphates which can form unwanted encrustations within the crevice regions 30 and hence impair the cleaning operation, as well as halides which are known to promote the occurrence of unwanted corrosion.
  • surfactants which are suitable for use in the method of the invention include Immunol 236 available from the Harry Miller Company located in Philadelphia, Pennsylvania, U.S.A., Surfynol 104, available from Air Products located in Allentown, Pennsylvania, U.S.A., Triton X100 available from Rohm & Haas located in Philadelphia, Pennsylvania, U.S.A., and Hamposyl L, which is available from the W. R. Grace Company located in Nashua, New Hampshire, U.S.A.
  • surfactants whose primary active ingredients include either a combination of alkylphenoy ethoxylate, ethylene oxide and fatty alkanol amide, or tertiary acetylenic diol, or octyphenoxypoly ethoxyethanol, or lauroyl sarcosine are suitable for use in the method of the invention.
  • Surfynol 104 is the most preferred because it has proven to be virtually non-foaming when subjected to the near-explosive burst of pressurized gas generated by the pressure pulse generators 33a,b.
  • Dispersants which may be used in conjunction with the method of the invention include tannic acid, Wayplex 55-S, Wayplex 55-A, Indulin C, Indulin AT, polyocrylic acid and lignin in the form of Reax 68 W.
  • dispersants whose active ingredients include polyacrylates, acrylic polymers, polypropyloxy quarternium ammonium acetate, imidazoline acetate and aminedodecylbenzine sulfonate are suitable for use in the method of the invention.
  • Each of the aforementioned dispersants works by coating the small particles of sludge and other debris dislodged and fluidized within the cleaning solution by the pressure pulse generator 33a,b so that they do not agglomerate with one another.
  • Flotation agents which may be used in conjunction with the method of the invention include Emersol 221, or a mixture of Emersol 221 plus triethanolamine.
  • Emersol 221 may be obtained from Emery Industries located in Cincinnati, Ohio, U.S.A. More generically, flotation agents whose active ingredients are comprised mostly of 9-octadecenoic acid may be used in the method.
  • a cleaning solution including one or more of the group of the aforementioned surfactants, dispersants, thixotropes and flotation agents may be used in the method of the invention
  • a mixture of only a surfactant and a dispersant is the most preferred mode of implementing the method of the invention.
  • flotation agents help to keep particles of sludge and debris in suspension, they also tend to drive a disproportionate amount of the particulate sludge and other debris near the surface of the cleaning agent present within the interior of the secondary side 5, and hence far away from the suction conduits 48a,b.
  • thixotropes help to keep such particulate matter in suspension by thickening the cleaning agent; they also impair the ability of the cleaning agent to penetrate small crevice regions such as the annular space 30 between the heat exchanger tubes 9 and the bores 28 in the support plate 26.
  • these generators are actuated to commence the introduction of pressurized pulses of gas into the solution in order to generate shock waves that effectively loosen and dislodge sludge and other debris from the metallic surfaces within the secondary side 5.
  • these shock waves are induced by pulses of gas pressurized to about 2.76 MPa.
  • the pressure of these gas pulses is proportionately increased to a maximum of about 6.21 MPa until the level of cleaning solution is about the same level as the uppermost bent portions of the heat exchanger tubes 9.
  • This proportionate increase in the pressure of the gas pulses counteracts the tendency of the gradually increasing level of the hydrostatic pressure of the solution at the bottom of the secondary side 5 to reduce the intensity of the shock waves generated by the pressure pulse generators 33a,b.
  • the frequency of the pressure pulses generated by the pressure pulses generators 33a,b takes place at intervals of between 10 and 60 seconds, and is preferably one pulse every ten seconds.
  • the filling step may be implemented with a flow rate through the inlet conduits 82a,b of as little as 94.64 litres per minute, a relatively fast flow rate of 946.4 litres per minute is preferred in order to shorten the total amount of time required for the method to be completed.
  • the recirculation step of the method may be commenced by actuating the suction pump 54.
  • the flow rate of the suction pump 54 is adjusted so that it is less than that of introduction pump 80 until the level of cleaning solution is about even with the height of the bundle of heat exchanger tubes 9, whereupon the rate of solution introduction and the rate of solution withdrawal are made equal.
  • the recirculation of the cleaning solution preferably takes place at a rate of between approximately 283.9 to 946.4 litres per minute. All during this step, the recirculated solution is continuously filtered by the filter units 60a,b, 64a,b of the filtration system 56.
  • the recirculation of the cleaning solution along with continuous pressure pulsing is between 16 and 24 hours to insure that the bulk of the sludge and other deposits initially present within the secondary side 5 is removed.
  • the filter bags and cartridges present in the filter units 60a,b are replaced as necessary during this step.
  • the secondary side 5 is drained by either de-actuating the introduction pump 80 or by reducing the flow rate of the introduction pump 80 relative to the suction pump 54.
  • the state of the isolation valves 76a,b,c is changed so that the net amount of cleaning solution drained from the secondary side 5 is forced to flow through the resin bed 74 to remove the dissolved ionic species and active cleaning agents from the solution and render it back into de-mineralized water.
  • the rate of flow of the introduction pump 80 is set lower than that of the suction pump 54, and the state of the isolation valves 76a,b,c is again reversed to continue the draining step. The draining step is then continued until substantially all of the cleaning solution is removed from the interior of the secondary side 5.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Cleaning In General (AREA)
  • Cleaning By Liquid Or Steam (AREA)
  • Incineration Of Waste (AREA)
  • Treatment Of Sludge (AREA)

Claims (19)

  1. Procédé pour retirer de la boue et des dépôts (32) de l'intérieur d'une cuve (1) d'échangeur de chaleur, qui comprend les étapes consistant à :
    - introduire un liquide à l'intérieur de la cuve, et
    - introduire une succession d'impulsions de gaz sous pression dans le liquide pour produire des ondes de choc qui détachent et retirent ladite boue et lesdits dépôts de l'intérieur de ladite cuve, caractérisé en ce que ledit liquide contient un agent nettoyant formé par au moins un produit du groupe constitué par les agents tensio-actifs, les agents dispersants, les agents thixotropes et les agents de flottation afin de favoriser la mise en suspension de ladite boue et desdits dépôts (32) et d'empêcher qu'ils ne se redéposent.
  2. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 1, dans lequel ledit agent nettoyant contient en outre un agent anti-mousse.
  3. Procédé pour retirer de la boue et des dépôts selon la revendication 1, dans lequel ledit agent nettoyant constitue moins de 1% en poids dudit liquide.
  4. Procédé pour retirer de la boue et des dépôts selon la revendication 1, dans lequel ledit agent nettoyant ne contient pas de sodium, de phosphates, d'halogénures ni de sulfates.
  5. Procédé pour retirer de la boue et des dépôts selon la revendication 1, dans lequel ledit agent nettoyant constitue entre environ 0,1 et 0,5 % en poids dudit liquide.
  6. Procédé pour retirer de la boue et des dépôts selon la revendication 1, caractérisé en outre par l'étape consistant à mettre en circulation ledit liquide à travers une installation de filtration (56) quand ladite succession d'impulsions de gaz sous pression est introduite dans le liquide, afin de retirer la boue et les dépôts (32) entraînés dans le liquide.
  7. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 6, caractérisé en outre par l'étape consistant à mettre en circulation ledit liquide à travers un milieu d'échange ionique (74) afin de retirer dudit liquide de la boue et des dépôts dissous.
  8. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 1, caractérisé en outre par les étapes séquentielles consistant à remplir sensiblement ladite cuve (1) avec ledit liquide, à mettre en circulation ledit liquide à l'intérieur de la cuve et à évacuer ledit liquide de ladite cuve (1) tout en introduisant en continu ladite succession d'impulsions sous pression pendant lesdites étapes de remplissage, mise en circulation et évacuation.
  9. Procédé pour retirer de la boue et des dépôts selon la revendication 8, dans lequel la pression du gaz utilisé pour créer lesdites impulsions augmente d'environ 2,76 à 6,21 MPa à mesure que la cuve se remplit dudit liquide, est maintenue à environ 6,21 MPa pendant ladite étape de mise en circulation et diminue d'environ 6,21 à 2,76 MPa lors de l'évacuation dudit liquide.
  10. Procédé pour retirer de la boue et des dépôts selon la revendication 1, dans lequel la fréquence desdites impulsions sous pression est d'une impulsion toutes les 10 à 60 secondes environ.
  11. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 1, dans lequel ledit liquide est fait de la combinaison d'un agent tensio-actif qui favorise la pénétration de ladite solution dans des régions crevassées à l'intérieur de ladite cuve (1) d'échangeur de chaleur et d'un agent dispersant qui favorise la mise en solution de ladite boue et desdits dépôts (32).
  12. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 1, dans lequel ledit agent dispersant est au moins un élément choisi dans le groupe formé par les polyacrylates, les polymères acryliques, l'acétate de poly(propyloxy)-ammonium quaternaire, l'acétate d'imidazoline et l'aminododécylbenzène sulfonate.
  13. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 1, dans lequel ledit agent tensio-actif est au moins un élément choisi dans le groupe formé par l'alkylphénoxy-éthoxylate, l'alcanolamide gras-oxyde d'éthylène, le diol acéthylènique tertiaire, l'octyéphénoxy-polyéthoxy-éthanol et la lauroyl-sarcosine.
  14. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 1, dans lequel ledit agent de flottation est de l'acide 9-octadécénoique.
  15. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 1, dans lequel ledit agent thixotrope est un polyacrylate réticulé.
  16. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 6, dans lequel ledit liquide est mis en circulation à un débit compris entre environ 94,6 et 567,8 litres par minute afin de maintenir l'entraînement de la boue et des dépôts (32) dans le liquide lorsqu'il s'écoule vers ladite installation de filtration (56).
  17. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 8, dans lequel ladite étape d'évacuation est arrêtée quand le niveau du liquide dans ledit échangeur de chaleur (1) atteint une valeur choisie et dans lequel la mise en circulation dudit liquide recommence jusqu'à ce que la densité de boue et de dépôts (32) entraînés dans ledit liquide atteigne un niveau choisi, après quoi ladite étape d'évacuation recommence.
  18. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 1, dans lequel le pourcentage pondéral total dudit agent par rapport à l'eau composant le liquide se situe entre environ 0,1 et 0,5%.
  19. Procédé pour retirer de la boue et des dépôts (32) selon la revendication 6, dans lequel ladite étape de mise en circulation dure entre 1 et 30 heures.
EP19910309816 1990-10-29 1991-10-23 Méthode pour enlever les boues et les dépôts à l'intérieur d'un réservoir d'échangeur de chaleur Expired - Lifetime EP0484042B1 (fr)

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US605200 1990-10-29

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EP0484042B1 true EP0484042B1 (fr) 1995-04-26

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Publication number Priority date Publication date Assignee Title
US5280701A (en) * 1992-08-31 1994-01-25 Environmental Energy Systems, Inc. Waste treatment system and method utilizing pressurized fluid
FR2761803A1 (fr) * 1997-04-04 1998-10-09 Framatome Sa Procede d'enlevement de matiere deposee sur une surface d'un circuit ou composant d'un reacteur nucleaire et applications du procede
KR100405156B1 (ko) * 2001-05-10 2003-11-12 김선욱 고압 세정장치
US20100300218A1 (en) * 2009-06-02 2010-12-02 Electric Power Research Institute, Inc. Dispersant application for clean-up of recirculation paths of a power producing facility during start-up
CA3029788C (fr) 2015-07-23 2021-07-27 Renmatix, Inc. Procede et appareil d'elimination d'une substance d'encrassement d'un recipient sous pression
CN119281769B (zh) * 2024-12-10 2025-03-11 江苏优驱机电科技有限公司 管路检测清洁装置、清洁处理系统及伴生气净化方法

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US3447965A (en) * 1966-10-31 1969-06-03 Dow Chemical Co Removal of copper containing scale from ferrous surfaces
JPS54120449A (en) * 1978-03-10 1979-09-19 Mitsubishi Heavy Ind Ltd Method and apparatus for cleansing minute gaps
US4320528A (en) * 1980-01-23 1982-03-16 Anco Engineers, Inc. Ultrasonic cleaner
US4632705A (en) * 1984-03-20 1986-12-30 Westinghouse Electric Corp. Process for the accelerated cleaning of the restricted areas of the secondary side of a steam generator
DE3533886A1 (de) * 1985-04-16 1987-03-26 Kraftwerk Union Ag Reinigungsverfahren
US4921662A (en) * 1988-04-19 1990-05-01 Westinghouse Electric Corp. Pressure pulse cleaning method
JPH04227487A (ja) * 1990-05-18 1992-08-17 Westinghouse Electric Corp <We> スラッジ及び腐食生成物の除去方法

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JP2952090B2 (ja) 1999-09-20
JPH04281196A (ja) 1992-10-06
EP0484042A1 (fr) 1992-05-06

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