JP2018151132A - Cleaning method of heat exchanger - Google Patents
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Description
本発明は、冷却水系、給湯器、ボイラ、半導体洗浄水濃縮等に用いられる熱交換器の洗浄に使用される熱交換器の洗浄方法に関するものである。より詳しくは、熱交換器に付着するスケール、特にカルシウムやシリカを含むスケールを容易に除去することができる熱交換器の洗浄方法に関するものである。 The present invention relates to a heat exchanger cleaning method used for cleaning a heat exchanger used for cooling water systems, hot water heaters, boilers, semiconductor cleaning water concentration, and the like. More specifically, the present invention relates to a heat exchanger cleaning method capable of easily removing scales adhering to a heat exchanger, particularly scales containing calcium and silica.
冷却水系や給湯器等に用いられる熱交換器は、用途に応じてプレート式や、シェル＆チューブ式、フィンチューブ式などのチューブ式等が用いられる。プレートやチューブは銅、アルミニウム、鉄、ステンレス等の金属材料により形成されるが、プレートはステンレスが、チューブは熱伝導率の高い銅が主として用いられる。シェル内やプレート間空隙には熱を受ける或いは与える第一流体が流通し、チューブ内や前記プレート間に隣接するプレート間空隙には前記第一流体と熱交換する第二流体が流通し、これらの第一流体と第二流体とでチューブ壁やプレート等を介して熱交換するように構成されている。ここで、第一流体が水系の場合、水にはカルシウム、マグネシウム等の硬度成分やシリカ等が含有されているため、熱交換器内には、長期間にわたって水を流通させる等により、水による熱交換器の腐食に起因する金属腐食生成物が付着するとともに水内の硬度成分やシリカ等に起因するスケールがチューブの外、流入するプレート壁に付着し、熱交換器の能力の低下により運転に支障をきたすようになる。なお、第二流体が水系の場合には、スケールはチューブの内、流入するプレート壁に付着する。 As a heat exchanger used for a cooling water system, a water heater, or the like, a plate type, a tube type such as a shell and tube type, a fin tube type, or the like is used depending on the application. The plate and the tube are made of a metal material such as copper, aluminum, iron, and stainless steel. The plate is mainly made of stainless steel, and the tube is mainly made of copper having high thermal conductivity. A first fluid that receives or applies heat flows through the shell or between the plates, and a second fluid that exchanges heat with the first fluid flows through the tube or between the plates adjacent to the plate. The first fluid and the second fluid are configured to exchange heat via a tube wall or a plate. Here, when the first fluid is water-based, water contains hardness components such as calcium and magnesium, silica, and the like. Therefore, in the heat exchanger, water is circulated for a long period of time. The metal corrosion products resulting from corrosion of the heat exchanger adhere, and the scale due to hardness components in the water and silica adheres to the inflowing plate wall outside the tube, resulting in reduced heat exchanger capacity. Will be disturbed. When the second fluid is an aqueous system, the scale adheres to the inflowing plate wall in the tube.
従来、熱交換器内の金属腐食生成物やスケールを除去するための洗浄剤は酸を含有している（ 例えば、特許文献１、特許文献２、特許文献３参照）。そして、洗浄剤が熱交換器内に流入されたときには、酸によって金属腐食生成物等を溶解することにより熱交換器内を洗浄するが、フレーム等の鉄製部品も腐食させる他、シリカスケールは除去が難しいという問題があった。
Conventionally, cleaning agents for removing metal corrosion products and scales in heat exchangers contain an acid (see, for example,
鉄腐食とシリカスケール除去の改良として、被洗浄対象物を鉄製部材から取り外してからカルシウムスケール用酸性液とシリカスケール用フッ化水素アンモニウムを主成分とする酸性液により除去する洗浄方法（特許文献４）、有機酸又はその塩を含有する酸溶液と水酸化カリウム又は水酸化ナトリウム含有のアルカリ溶液で順次洗浄する洗浄方法（特許文献５）、および酸性洗浄剤による洗浄処理、次いで乾燥処理、次いでアルカリ性洗浄剤による洗浄処理を行うスケールの除去方法（特許文献６）が開示されている。 As an improvement of iron corrosion and silica scale removal, a cleaning method in which an object to be cleaned is removed from an iron member and then removed with an acidic liquid mainly composed of calcium scale acidic liquid and silica scale ammonium hydrogen fluoride (Patent Document 4). ), An acid solution containing an organic acid or a salt thereof and an alkaline solution containing potassium hydroxide or sodium hydroxide (Patent Document 5), and a washing treatment with an acidic detergent, followed by a drying treatment and then an alkaline solution A scale removal method (Patent Document 6) for performing a cleaning treatment with a cleaning agent is disclosed.
ところが、従来の洗浄方法では洗浄の終点を把握することができないので、スケールを完全に除去するために過剰に高濃度の洗浄液で長時間の洗浄を行ったり、あるいは、スケールの除去状況を把握するために、洗浄を一時的に中断して熱交換器内部を目視等で確認したりしなければならないという問題があった。 However, since the end point of cleaning cannot be grasped by the conventional cleaning method, in order to completely remove the scale, it is possible to perform cleaning for a long time with an excessively high concentration cleaning solution or to grasp the removal state of the scale. Therefore, there has been a problem that the cleaning must be temporarily interrupted to visually check the inside of the heat exchanger.
本発明は、このような従来技術に存在する問題点に着目してなされたものである。その目的とするところは、熱交換器に付着したスケール、特にカルシウムやシリカを含むスケールを洗浄する際に、洗浄の終点を容易に見極めることができ、スケールの除去状況確認のために洗浄を中断することなく定置洗浄が可能な熱交換器の洗浄方法を提供することにある。 The present invention has been made paying attention to such problems existing in the prior art. The objective is to easily determine the end point of cleaning when cleaning scales attached to heat exchangers, especially scales containing calcium or silica, and interrupting the cleaning to check the scale removal status. It is an object of the present invention to provide a heat exchanger cleaning method that can perform stationary cleaning without the need for cleaning.
上記の目的を達成するために、
（１）
第１の発明は、流体用容器と、該流体用容器の内部に設けられた熱交換部材とを備えた熱交換器の洗浄方法であって、第一洗浄液を前記熱交換部材内又は流体用容器に流入、循環させ、定期的に循環水の第一洗浄液濃度指標を測定して該濃度指標の低下が実質停止するまで第一洗浄液を追加流入させて第一洗浄液濃度を制御することで前記熱交換部材に付着したスケールを膨潤又は剥落させ、その後、第二洗浄液を、前記熱交換部材内又は流体用容器に流入し、循環させ、定期的に循環水の第二洗浄液濃度指標を測定して該濃度指標の低下が実質停止するまで第二洗浄液を追加流入させて第二洗浄液濃度を制御することで前記熱交換部材に付着したスケールを溶解除去する熱交換器の洗浄方法である。
（２） 第２の発明は、第１の発明において、前記第一洗浄液が酸溶液であり、第二洗浄液が水に溶解してフッ化物イオンを生成するフッ化物を含むフッ化物水溶液である熱交換器の洗浄方法である。
（３） 第３の発明は、第２の発明において、前記フッ化物水溶液がフッ化水素アンモニウムを含有する熱交換器の洗浄方法である。
（４） 第４の発明は、第２または第３の発明において、前記熱交換部材内又は流体用容器に流入させた酸溶液の循環水の酸濃度指標、およびフッ化物水溶液の循環水のフッ化物濃度指標として酸濃度を用いる熱交換器の洗浄方法である。
（５） 第５の発明は、第２から第４のいずれかの発明において、前記熱交換器にステンレス製およびチタン製の部材が使用されていない熱交換器の洗浄方法である。
（６） 第６の発明は、第１の発明において、前記第一洗浄液が酸溶液であり、該酸溶液を、前記熱交換部材内又は流体用容器に流入、循環させ、定期的に循環水の酸濃度指標を測定して酸濃度指標の低下が実質停止するまで酸溶液を追加流入させて濃度を制御することで前記熱交換部材に付着したスケールを膨潤又は剥落させ、次いで、前記熱交換部材内又は流体用容器から酸溶液を排出し、その後、第二洗浄液としてアルカリ溶液を、前記熱交換部材内又は流体用容器に流入、循環させ、定期的に循環水のアルカリ濃度指標を測定してアルカリ濃度指標の低下が実質停止するまでアルカリ溶液を追加流入させてアルカリ濃度を制御することで前記熱交換部材に付着したスケールを溶解除去する熱交換器の洗浄方法である。
（７） 第７の発明は、第６の発明において、前記アルカリ溶液が、水酸化カリウム及び水酸化ナトリウムから選ばれる少なくとも一種を含有するアルカリ溶液である熱交換器の洗浄方法である。
（８） 第８の発明は、第６または第７の発明において、前記アルカリ溶液が、キレート作用及びスケール分散作用を有する沈殿防止剤を含有する熱交換器の洗浄方法である。
（９） 第９の発明は、第６から第８のいずれかの発明において、前記熱交換器にステンレス製またはチタン製の部材が使用されている熱交換器の洗浄方法である。
（１０） 第１０の発明は、第６から第９のいずれかの発明において、前記熱交換部材内又は流体用容器に流入させたアルカリ溶液の循環水のアルカリ濃度指標としてアルカリ濃度を用いる熱交換器の洗浄方法である。
（１１） 第１１の発明は、第６から第１０のいずれかの発明において、前記酸溶液及びアルカリ溶液が、食品添加物により構成されている熱交換器の洗浄方法である。
（１２） 第１２の発明は、第１から第１１のいずれかの発明において、前記酸溶液が、水溶性カルボン酸類、スルファミン酸、メタンスルホン酸、及びそれらの塩から選ばれる少なくとも一種を含有する溶液である熱交換器の洗浄方法である。
（１３） 第１３の発明は、第１から第１２のいずれかの発明において、前記酸溶液が、キレート作用及びスケール分散作用を有する洗浄性向上剤を含有する熱交換器の洗浄方法である。
（１４） 第１４の発明は、前記酸溶液が、第１から第１３のいずれかの発明において、スルファミン酸またはその塩を含有する熱交換器の洗浄方法である。
To achieve the above objective,
(1)
A first invention is a heat exchanger cleaning method comprising a fluid container and a heat exchange member provided inside the fluid container, wherein the first cleaning liquid is used in the heat exchange member or fluid. The first cleaning liquid concentration is controlled by controlling the first cleaning liquid concentration by adding the first cleaning liquid until the first cleaning liquid concentration index of the circulating water is periodically measured and the decrease in the concentration index is substantially stopped. The scale adhering to the heat exchange member is swollen or peeled off, and then the second cleaning liquid flows into the heat exchange member or fluid container and circulates, and periodically measures the second cleaning liquid concentration index of the circulating water. Thus, the second cleaning liquid is additionally introduced until the decrease in the concentration index substantially stops, and the concentration of the second cleaning liquid is controlled to dissolve and remove the scale attached to the heat exchange member.
(2) The second invention is the heat according to the first invention, wherein the first cleaning liquid is an acid solution, and the second cleaning liquid is a fluoride aqueous solution containing fluoride that generates fluoride ions by dissolving in water. This is a cleaning method for the exchanger.
(3) The third invention is the heat exchanger cleaning method according to the second invention, wherein the fluoride aqueous solution contains ammonium hydrogen fluoride.
(4) According to a fourth invention, in the second or third invention, the acid concentration index of the circulating water of the acid solution that has flowed into the heat exchange member or the fluid container, and the circulating water hook of the aqueous fluoride solution. This is a heat exchanger cleaning method that uses acid concentration as a chemical concentration indicator.
(5) 5th invention is the washing | cleaning method of the heat exchanger in which stainless steel and the member made from titanium are not used for the said heat exchanger in any one of 2nd-4th invention.
(6) In a sixth aspect based on the first aspect, the first cleaning liquid is an acid solution, and the acid solution is caused to flow into and circulate in the heat exchange member or the fluid container to periodically circulate water. The acid concentration index is measured and the acid attached to the heat exchange member is swollen or peeled off by controlling the concentration by adding an acid solution until the decrease in the acid concentration index substantially stops, and then the heat exchange. The acid solution is discharged from the member or the fluid container, and then an alkaline solution as the second cleaning liquid flows into and circulates in the heat exchange member or the fluid container, and periodically measures the alkali concentration index of the circulating water. In this heat exchanger cleaning method, the scale adhering to the heat exchange member is dissolved and removed by additionally introducing an alkaline solution and controlling the alkali concentration until the decrease in the alkali concentration index substantially stops.
(7) A seventh invention is a cleaning method for a heat exchanger according to the sixth invention, wherein the alkaline solution is an alkaline solution containing at least one selected from potassium hydroxide and sodium hydroxide.
(8) The eighth invention is the cleaning method for a heat exchanger according to the sixth or seventh invention, wherein the alkaline solution contains a precipitation inhibitor having a chelating action and a scale dispersing action.
(9) A ninth invention is a method of cleaning a heat exchanger according to any one of the sixth to eighth inventions, wherein a member made of stainless steel or titanium is used for the heat exchanger.
(10) In a tenth aspect of the invention according to any one of the sixth to ninth aspects, heat exchange using an alkali concentration as an alkali concentration index of circulating water of an alkaline solution that has flowed into the heat exchange member or the fluid container. This is a cleaning method for the vessel.
(11) An eleventh aspect of the invention is a heat exchanger cleaning method according to any one of the sixth to tenth aspects, wherein the acid solution and the alkaline solution are constituted by food additives.
(12) In a twelfth invention according to any one of the first to eleventh inventions, the acid solution contains at least one selected from water-soluble carboxylic acids, sulfamic acid, methanesulfonic acid, and salts thereof. This is a method for cleaning a heat exchanger that is a solution.
(13) A thirteenth aspect of the present invention is the heat exchanger cleaning method according to any one of the first to twelfth aspects, wherein the acid solution contains a detergency improver having a chelating action and a scale dispersing action.
(14) A fourteenth aspect of the invention is a method for cleaning a heat exchanger, wherein the acid solution contains sulfamic acid or a salt thereof in any one of the first to thirteenth aspects.
以上詳述したように、本発明の熱交換器の洗浄方法によれば、洗浄終点を容易に見極められ、特にカルシウムやシリカを含むスケールを容易に除去することができる。また、熱交換器の洗浄に際して冷却水系、給湯器、ボイラ水系、半導体洗浄水系等から熱交換器を取り外す必要は無く、定置洗浄が可能となる。 As described above in detail, according to the heat exchanger cleaning method of the present invention, the end point of cleaning can be easily determined, and in particular, scales containing calcium and silica can be easily removed. Further, when cleaning the heat exchanger, it is not necessary to remove the heat exchanger from the cooling water system, the hot water heater, the boiler water system, the semiconductor cleaning water system, etc., and stationary cleaning is possible.
本発明の、第一の洗浄方法は、内部に熱交換部材が設けられた流体用容器に、酸溶液、好ましくは水溶性カルボン酸類、スルファミン酸、メタンスルホン酸、及びそれらの塩の酸溶液を循環させ、経時の濃度変化が実質停止するまで追加流入させて酸濃度を制御することにより熱交換器に付着したシリカ系スケールを同酸溶液により膨潤又は剥落させ、その後、水に溶解してフッ化物イオンを生成するフッ化物を含むフッ化物水溶液、好ましくはフッ化水素アンモニウム溶液を循環させ、経時の濃度変化が実質停止するまで追加流入させることにより溶解させるという簡単な操作で、カルシウムやシリカを含むスケールを容易に除去することができる。 In the first cleaning method of the present invention, an acid solution, preferably an acid solution of water-soluble carboxylic acids, sulfamic acid, methanesulfonic acid, and salts thereof is placed in a fluid container provided with a heat exchange member. The silica scale adhering to the heat exchanger is swollen or peeled off by the acid solution by controlling the acid concentration by circulating and adding additional flow until the concentration change over time is substantially stopped, and then dissolving in the water to fluorinate. Calcium and silica can be dissolved by a simple operation of circulating an aqueous fluoride solution containing fluoride that generates fluoride ions, preferably an ammonium hydrogen fluoride solution, and dissolving it by additional inflow until the concentration change over time substantially stops. The containing scale can be easily removed.
本発明の第二の洗浄方法は、内部に熱交換部材が設けられた流体用容器に、酸溶液、好ましくは水溶性カルボン酸類、スルファミン酸、メタンスルホン酸、及びそれらの塩の酸溶液を循環させ、経時の濃度変化が実質停止するまで追加流入させて酸濃度を制御することにより熱交換器に付着したシリカ系スケールを同酸溶液により膨潤又は剥落させ、同酸溶液を流体容器から排出した後にアルカリ溶液、好ましくは水酸化カリウム及び水酸化ナトリウムから選ばれる少なくとも一種の溶液を循環させ、経時の濃度変化が実質停止するまで追加流入させることにより溶解させるという簡単な操作で、カルシウムやシリカを含むスケールを容易に除去することができる。この方法は、特に熱交換器がステンレス製またはチタン製である場合に洗浄による腐食の発生を抑えられるので好ましい。 In the second cleaning method of the present invention, an acid solution, preferably an acid solution of water-soluble carboxylic acids, sulfamic acid, methanesulfonic acid, and salts thereof is circulated in a fluid container provided with a heat exchange member. The silica scale adhering to the heat exchanger was swollen or peeled off by the acid solution by controlling the acid concentration by adding an additional flow until the concentration change over time substantially stopped, and discharging the acid solution from the fluid container. Thereafter, an alkaline solution, preferably at least one solution selected from potassium hydroxide and sodium hydroxide, is circulated and dissolved by further inflow until the concentration change with time is substantially stopped, so that calcium and silica are dissolved. The containing scale can be easily removed. This method is preferable because the occurrence of corrosion due to cleaning can be suppressed particularly when the heat exchanger is made of stainless steel or titanium.
以下、本発明の実施形態について具体的に説明する。
本発明の熱交換器の洗浄方法は、第一洗浄液として、酸溶液、好ましくは水溶性カルボン酸類、スルファミン酸、メタンスルホン酸、及びそれらの塩から選ばれる少なくとも一種を含有する酸溶液を内部に熱交換部材が設けられた流体用容器に流入、循環させ、定期的に循環水の酸濃度指標を測定して酸濃度指標の低下が実質停止するまで酸溶液を追加流入させて酸濃度を制御し、その後、第二洗浄液として、水に溶解してフッ化物イオンを生成するフッ化物を含むフッ化物水溶液、好ましくはフッ化水素アンモニウム、フッ化水素ナトリウム、フッ化水素カリウム溶液の少なくともいずれかを、流体用容器の循環水に流入、循環させ、定期的に循環水のフッ化物濃度指標を測定してフッ化物濃度指標の低下が実質停止するまでフッ化物溶液を追加流入させてフッ化物濃度を制御するものである。
Hereinafter, embodiments of the present invention will be specifically described.
The heat exchanger cleaning method of the present invention includes, as a first cleaning liquid, an acid solution, preferably an acid solution containing at least one selected from water-soluble carboxylic acids, sulfamic acid, methanesulfonic acid, and salts thereof. Flow into and circulate through a fluid container equipped with a heat exchange member, periodically measure the acid concentration index of the circulating water, and control the acid concentration by adding an acid solution until the decrease in the acid concentration index substantially stops. Then, as the second cleaning liquid, an aqueous fluoride solution containing fluoride that dissolves in water to generate fluoride ions, preferably at least one of ammonium hydrogen fluoride, sodium hydrogen fluoride, and potassium hydrogen fluoride solution. , Flow into and circulate the circulating water in the fluid container, periodically measure the fluoride concentration index of the circulating water, and the fluoride solution until the decrease in the fluoride concentration index substantially stops It controls the fluoride concentration by adding inlet.
本発明の他の熱交換器の洗浄方法は、第一洗浄液として、酸溶液、好ましくは水溶性カルボン酸類、スルファミン酸、メタンスルホン酸、及びそれらの塩から選ばれる少なくとも一種を含有する酸溶液を、内部に熱交換部材が設けられた流体用容器に流入、循環させ、定期的に循環水の酸濃度指標を測定して酸濃度指標の低下が実質停止するまで酸溶液を追加流入させ、次いで、流体用容器から酸溶液を排出し、その後、第二洗浄液として、アルカリ溶液、好ましくは水酸化カリウム及び水酸化ナトリウムから選ばれる少なくとも一種を、流体用容器に流入、循環させ、定期的に循環水のアルカリ濃度指標を測定してアルカリ濃度指標の低下が実質停止するまでアルカリ溶液を追加流入させてアルカリ濃度を制御するものである。 In another heat exchanger cleaning method of the present invention, an acid solution, preferably an acid solution containing at least one selected from water-soluble carboxylic acids, sulfamic acid, methanesulfonic acid, and salts thereof is used as the first cleaning liquid. , Flow into and circulate into a fluid container provided with a heat exchange member inside, periodically measure the acid concentration index of the circulating water and add the acid solution until the decrease in the acid concentration index substantially stops, then The acid solution is discharged from the fluid container, and then, as the second cleaning liquid, at least one selected from an alkaline solution, preferably potassium hydroxide and sodium hydroxide, flows into and circulates the fluid container, and is periodically circulated. The alkali concentration index is measured by measuring the alkali concentration index of water and adding an alkaline solution until the decrease in the alkali concentration index substantially stops.
本発明で使用する洗浄剤について説明する。
酸溶液に含まれる酸成分は、例えば水溶性カルボン酸として蟻酸、マロン酸、シュウ酸、マレイン酸、フマル酸、リンゴ酸、クエン酸、グリコール酸、乳酸、酒石酸、及びそれらの塩等が挙げられ、スルホン酸としてメタンスルホン酸、及びその塩、無機酸は塩酸、硝酸、リン酸、ポリリン酸、ホウ酸、硫酸および亜硫酸、スルファミン酸、及びその塩、等が挙げられる。好ましくはスルファミン酸またはその塩が用いられる。
The cleaning agent used in the present invention will be described.
Examples of the acid component contained in the acid solution include formic acid, malonic acid, oxalic acid, maleic acid, fumaric acid, malic acid, citric acid, glycolic acid, lactic acid, tartaric acid, and salts thereof as water-soluble carboxylic acids. Examples of the sulfonic acid include methanesulfonic acid and salts thereof, examples of the inorganic acid include hydrochloric acid, nitric acid, phosphoric acid, polyphosphoric acid, boric acid, sulfuric acid and sulfurous acid, sulfamic acid, and salts thereof. Preferably, sulfamic acid or a salt thereof is used.
流体用容器内の循環水における酸溶液の酸成分の濃度は、０．５質量％から２０質量％、好ましくは５質量％から１０質量％である。濃度が低すぎると洗浄効果が得にくく、高すぎても増加に見合った洗浄効果の向上が得られない。 The concentration of the acid component of the acid solution in the circulating water in the fluid container is 0.5% by mass to 20% by mass, preferably 5% by mass to 10% by mass. If the concentration is too low, it is difficult to obtain a cleaning effect, and if it is too high, an improvement in cleaning effect commensurate with the increase cannot be obtained.
酸濃度指標は、酸濃度、または計測対象溶液の酸濃度と対応関係を有しており、酸濃度に変換することができる特性値である。例えば、計測対象溶液の酸濃度そのものの他、計測対象溶液のｐＨ、酸化還元電位等が用いられる。 The acid concentration index has a correspondence relationship with the acid concentration or the acid concentration of the solution to be measured, and is a characteristic value that can be converted into an acid concentration. For example, in addition to the acid concentration itself of the measurement target solution, the pH of the measurement target solution, the oxidation-reduction potential, and the like are used.
水に溶解してフッ化物イオンを生成するフッ化物は、例えばフッ化水素アンモニウム、フッ化水素ナトリウム、フッ化水素カリウム、フッ化水素アミンなどのフッ化水素化合物やフッ化アンモニウム、フッ化ナトリウム、フッ化カリウム、フッ化アミンなどが挙げられる。好ましくはフッ化水素アンモニウムが用いられる。 Fluorides that dissolve in water to produce fluoride ions are, for example, hydrogen fluoride compounds such as ammonium hydrogen fluoride, sodium hydrogen fluoride, potassium hydrogen fluoride, hydrogen fluoride amine, ammonium fluoride, sodium fluoride, Examples include potassium fluoride and amine fluoride. Preferably, ammonium hydrogen fluoride is used.
流体用容器内の循環水におけるフッ化物の濃度は、０．１質量％から１０質量％、好ましくは２質量％から５質量％である。濃度が低すぎると洗浄効果が得にくく、高すぎても増加に見合った洗浄効果の向上が得られない。 The concentration of fluoride in the circulating water in the fluid container is 0.1% by mass to 10% by mass, preferably 2% by mass to 5% by mass. If the concentration is too low, it is difficult to obtain a cleaning effect, and if it is too high, an improvement in cleaning effect commensurate with the increase cannot be obtained.
フッ化物濃度指標は、フッ化物濃度として、熱加水分解法によりフッ素含有物を加熱し、発生するフッ化物を含んだガスを分析する方法で得られるが、簡便かつ迅速な方法としてフッ化物を添加することによる酸濃度指標の変化を測定することによりフッ化物濃度に変換できる。 The fluoride concentration index is obtained by a method of heating the fluorine-containing material by the thermal hydrolysis method and analyzing the gas containing the generated fluoride as the fluoride concentration, but adding fluoride as a simple and rapid method It can be converted to fluoride concentration by measuring the change in the acid concentration index.
アルカリ溶液のアルカリ成分は、例えば水酸化ナトリウム、水酸化カリウム、水酸化カルシウム、炭酸ナトリウム、炭酸カリウム、ケイ酸ナトリウム、ケイ酸カリウム、アンモニアなどが挙げられ、好ましくは水酸化ナトリウム、水酸化カリウムが用いられる。 Examples of the alkaline component of the alkaline solution include sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, potassium silicate, and ammonia. Preferably, sodium hydroxide and potassium hydroxide are used. Used.
流体用容器内の循環水におけるアルカリ溶液のアルカリ成分の濃度は、０．５質量％から２０質量％、好ましくは２質量％から１０質量％である。濃度が低すぎると洗浄効果が得にくく、高すぎても増加に見合った洗浄効果の向上が得られない。 The concentration of the alkaline component of the alkaline solution in the circulating water in the fluid container is 0.5% by mass to 20% by mass, preferably 2% by mass to 10% by mass. If the concentration is too low, it is difficult to obtain a cleaning effect, and if it is too high, an improvement in cleaning effect commensurate with the increase cannot be obtained.
アルカリ濃度指標は、アルカリ濃度、または計測対象溶液のアルカリ濃度と対応関係を有しており、アルカリ濃度に変換することができる特性値である。例えば、計測対象溶液のアルカリ濃度そのものの他、計測対象溶液のｐＨ、酸化還元電位等が用いられる。 The alkali concentration index has a corresponding relationship with the alkali concentration or the alkali concentration of the solution to be measured, and is a characteristic value that can be converted into an alkali concentration. For example, in addition to the alkali concentration itself of the measurement target solution, the pH of the measurement target solution, the oxidation-reduction potential, and the like are used.
本発明で、酸溶液を前記流体用容器に流入、循環させ、定期的に循環水の酸濃度指標を測定して酸濃度指標の低下が実質停止するまで酸溶液を追加流入させて酸濃度を制御する場合の定期的に酸濃度指標を測定するとは、一定時間ごとに測定することであり、１０分から２時間の間隔で最適な間隔を決めて測定することが好まししい。定期的に循環水のフッ化物濃度指標を測定する場合、定期的に循環水のアルカリ濃度指標を測定する場合も一定時間ごとに測定することであり、１０分から２時間の間隔で測定することが好ましい。 In the present invention, the acid solution is caused to flow into and circulate through the fluid container, and the acid concentration index of the circulating water is periodically measured, and the acid concentration is adjusted by adding the acid solution until the decrease in the acid concentration index substantially stops. Measuring the acid concentration index periodically in the case of control is to measure at regular intervals, and it is preferable to determine an optimum interval from 10 minutes to 2 hours. When periodically measuring the fluoride concentration index of the circulating water, when measuring the alkaline concentration index of the circulating water regularly, it is also measured at regular intervals, and can be measured at intervals of 10 minutes to 2 hours. preferable.
本発明で、酸濃度指標の低下が実質停止するまで、フッ化物濃度指標の低下が実質停止するまで、およびアルカリ濃度指標の低下が実質停止するまでとは、各指標を測定した結果と、一定時間後に行った次の測定結果との差が実質ゼロになるまでであり、前後の測定指標の差が前測定指標の概略５％以内になるまでをいう。 In the present invention, until the decrease of the acid concentration index substantially stops, until the decrease of the fluoride concentration index substantially stops, and until the decrease of the alkali concentration index substantially stops, the results of measuring each index are constant. This is until the difference from the next measurement result made after time becomes substantially zero, and until the difference between the previous and next measurement indices is within approximately 5% of the previous measurement index.
本発明で、アルカリ溶液に含有させることができる、キレート作用及びスケール分散作用を有する沈殿防止剤は、剥落したシリカスケールの分散性を向上し、溶解したシリカスケール等が沈殿物として析出するのを防止する。沈殿防止剤の具体例としては、ポリマレイン酸等のマレイン酸系化合物、アミノトリ（メチレンホスホン酸）、１-ヒドロキシエチリデン-１，１-ジホスホン酸、エチレンジアミンテトラ（メチレンホスホン酸）、ヘキサメチレンジアミンテトラ（メチレンホスホン酸）、ジエチレンテトラミンペンタ（メチレンホスホン酸）、ホスホノカルボン酸、２−ホスホノブタン−１，２，４−トリカルボン酸等のホスホン酸系化合物、ポリリン酸ナトリウム、ポリリン酸カリウム等のポリリン酸系化合物、エチレンジアミン四酢酸（ＥＤＴＡ）−２Ｎａ等のＥＤＴＡ塩等が挙げられる。これらは単独で含有されてもよいし、二種以上を組み合わせて含有されてもよい。 これらの中でも、食品添加物として用いられるポリマレイン酸、ポリリン酸又はそれらのナトリウム塩、カリウム塩又はカルシウム塩等が、食品用機器に用いられる熱交換器の洗浄に使用することができるために好ましい In the present invention, the precipitation inhibitor having a chelating action and a scale dispersing action that can be contained in an alkaline solution improves the dispersibility of the peeled silica scale, and the dissolved silica scale and the like are precipitated as a precipitate. To prevent. Specific examples of the precipitation inhibitor include maleic acid compounds such as polymaleic acid, aminotri (methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid), hexamethylenediaminetetra ( Methylenephosphonic acid), diethylenetetraminepenta (methylenephosphonic acid), phosphonocarboxylic acid, phosphonic acid compounds such as 2-phosphonobutane-1,2,4-tricarboxylic acid, polyphosphoric acid compounds such as sodium polyphosphate and potassium polyphosphate Examples thereof include EDTA salts such as compounds and ethylenediaminetetraacetic acid (EDTA) -2Na. These may be contained alone or in combination of two or more. Among these, polymaleic acid, polyphosphoric acid used as a food additive, or a sodium salt, potassium salt, or calcium salt thereof is preferable because it can be used for washing heat exchangers used in food equipment.
本発明で、酸溶液に含有させることができる、キレート作用及びスケール分散作用を有する洗浄性向上剤としては、溶解した金属腐食生成物等が流体用容器の内表面等に再付着するのを防止し、剥落したシリカスケールの分散性を向上させることによって洗浄性を向上させる。洗浄性向上剤の具体例としては、前記のアルカリ溶液に含有させることができる沈殿防止剤と同様の化合物が使用可能である。 In the present invention, as a detergency improver having a chelating action and a scale dispersing action that can be contained in an acid solution, a dissolved metal corrosion product or the like is prevented from reattaching to the inner surface of a fluid container. And the detergency is improved by improving the dispersibility of the peeled silica scale. As a specific example of the detergency improver, the same compound as the precipitation inhibitor that can be contained in the alkaline solution can be used.
本発明における、酸溶液、フッ化物水溶液、及びアルカリ溶液の洗浄液の少なくとも何れかを用いた洗浄に際して、洗浄液に気泡を混入して洗浄することも可能である。特に熱交換器が洗浄時に気泡を滞留せずに速やかに流出する構造であれば気泡混入洗浄によりスケールをより効果的に除去することができ、スケールの付着状況により気泡の大きさや混入量を調整することでさらに効果的となる。 In the present invention, when cleaning is performed using at least one of an acid solution, an aqueous fluoride solution, and an alkaline solution, it is also possible to perform cleaning by mixing bubbles in the cleaning solution. In particular, if the heat exchanger has a structure that quickly flows out without retaining bubbles during cleaning, the scale can be more effectively removed by cleaning with bubbles, and the size and amount of bubbles can be adjusted according to the state of adhesion of the scale. It becomes more effective by doing.
（実施例１）
流体用容器４と、流体用容器４の内部に設けられた銅により形成されている熱交換部材４ａ（例えばチューブ）からなり、熱交換部材４ａの内又は外表面等に金属腐食生成物やシリカスケール等が付着している（シェル＆チューブ式）熱交換器４ｂに、仮設循環ライン３、仮設循環ポンプ２、仮設循環タンク１を含む仮設循環回路５（図１参照）を設け、スルファミン酸の含有量が８質量％に調整したスルファミン酸溶液を循環させて酸濃度を測定し、その後３０分毎に酸濃度を測定して直前の測定値から低下があれば初期の酸濃度になるまでスルファミン酸を追加し、連続した測定値間の酸濃度の低下がほぼ無くなれば、続いて、フッ化水素アンモニウムの含有量が３質量％に調整したフッ化水素アンモニウム溶液を循環させて酸濃度を測定し、その後３０分毎に酸濃度を測定して直前の測定値から低下あれば初期の酸濃度になるまでフッ化水素アンモニウムを追加し、連続した測定値間の酸濃度の低下がほぼ無くなれば洗浄液を流体用容器から排出し、浄水により流体用容器を洗浄した。ここで、各流体の温度は２０℃とし、酸濃度の測定には標準液として１ｍｏｌ／Ｌの水酸化ナトリウム溶液を用い、指示薬としてフェノールフタレイン溶液を用いた。
Example 1
It consists of a
(実施例２)
実施例１で、酸溶液中のスルファミン酸の含有量は８質量％で、フッ化水素アンモニウム溶液中のフッ化水素アンモニウムの含有量を７質量％とした以外は同様にして試験を行った。
(Example 2)
The test was conducted in the same manner as in Example 1 except that the content of sulfamic acid in the acid solution was 8% by mass and the content of ammonium hydrogen fluoride in the ammonium hydrogen fluoride solution was 7% by mass.
（実施例３）
実施例１で、酸溶液中のスルファミン酸の含有量は８質量％で、フッ化水素アンモニウム溶液中のフッ化水素アンモニウムの含有量を１質量％とした以外は同様にして試験を行った。
(Example 3)
In Example 1, the test was performed in the same manner except that the content of sulfamic acid in the acid solution was 8% by mass and the content of ammonium hydrogen fluoride in the ammonium hydrogen fluoride solution was 1% by mass.
（実施例４）
実施例１で、酸溶液中のスルファミン酸の含有量を１２質量％とし、フッ化水素アンモニウム溶液中のフッ化水素アンモニウムの含有量は３質量％とした以外は同様にして試験を行った。
(Example 4)
A test was conducted in the same manner as in Example 1 except that the content of sulfamic acid in the acid solution was 12 mass% and the content of ammonium hydrogen fluoride in the ammonium hydrogen fluoride solution was 3 mass%.
（実施例５）
実施例１で、酸溶液中のスルファミン酸の含有量を２質量％とし、フッ化水素アンモニウム溶液中のフッ化水素アンモニウムの含有量は３質量％とした以外は同様にして試験を行った。
(Example 5)
The test was performed in the same manner as in Example 1 except that the content of sulfamic acid in the acid solution was 2% by mass and the content of ammonium hydrogen fluoride in the ammonium hydrogen fluoride solution was 3% by mass.
（実施例６）
実施例１で、酸溶液中のスルファミン酸の含有量は８質量％で、フッ化水素アンモニウム溶液中のフッ化水素アンモニウムの含有量は８質量％とした以外は同様にして試験を行った。
(Example 6)
A test was conducted in the same manner as in Example 1 except that the content of sulfamic acid in the acid solution was 8% by mass and the content of ammonium hydrogen fluoride in the ammonium hydrogen fluoride solution was 8% by mass.
（実施例７）
実施例１で、酸溶液中のスルファミン酸の含有量は８質量％で、フッ化水素アンモニウム溶液中のフッ化水素アンモニウムの含有量は１質量％とした以外は同様にして試験を行った。
(Example 7)
A test was conducted in the same manner as in Example 1 except that the content of sulfamic acid in the acid solution was 8% by mass and the content of ammonium hydrogen fluoride in the ammonium hydrogen fluoride solution was 1% by mass.
（実施例８）
ステンレスにより形成されている２枚の熱交換部材４ａ（例えばプレート）が、流体流路形成ガスケットをサンドしてセットを構成するとともに、そのセットが複数積層されてなり、熱交換部材４ａの表面等に金属腐食生成物やシリカスケール等が付着している流体用容器４である（プレート式）熱交換器４ｂに、仮設循環ライン３、仮設循環ポンプ２、仮設循環タンク１を含む仮設循環回路５（図２参照）を設け、スルファミン酸の含有量が８質量％に調整したスルファミン酸溶液を循環させて酸濃度を測定し、その後３０分毎に酸濃度を測定して直前の測定値から低下があれば初期の酸濃度になるまでスルファミン酸溶液を追加し、連続した測定値間の酸濃度の低下がほぼ無くなれば仮設循環回路からスルファミン酸溶液を排出し、続いて、水酸化カリウムの含有量が６質量％に調整したアルカリ溶液を循環させてアルカリ濃度を測定し、その後３０分毎にアルカリ濃度を測定して直前の測定値からの低下があれば、初期のアルカリ濃度になるまで水酸化カリウムを追加し、連続した測定値間のアルカリ濃度の低下がほぼ無くなれば洗浄液を流体用容器から排出し、浄水により流体用容器を洗浄した。ここで、各流体の温度は２０℃とし、酸濃度の測定には標準液として１ｍｏｌ／Ｌの水酸化ナトリウム溶液を用い、指示薬としてフェノールフタレイン溶液を用いた。またアルカリ濃度の測定には標準液として１ｍｏｌ／Ｌの塩酸溶液を用い、指示薬としてブロモクレゾールグリーン・メチルレッド混合溶液を用いた。
(Example 8)
Two
（実施例９）
実施例８で、酸溶液中のスルファミン酸の含有量は８質量％で、アルカリ溶液中の水酸化カリウムの含有量を１２質量％とした以外は同様にして試験を行った。
Example 9
In Example 8, the test was performed in the same manner except that the content of sulfamic acid in the acid solution was 8% by mass and the content of potassium hydroxide in the alkaline solution was 12% by mass.
（実施例１０）
実施例８で、酸溶液中のスルファミン酸の含有量は８質量％で、アルカリ溶液中の水酸化カリウムの含有量を１質量％とした以外は同様にして試験を行った。
(Example 10)
In Example 8, the test was performed in the same manner except that the content of sulfamic acid in the acid solution was 8% by mass and the content of potassium hydroxide in the alkaline solution was 1% by mass.
（実施例１１）
実施例８で、酸溶液中のスルファミン酸の含有量を１２質量％とし、アルカリ溶液中の水酸化カリウムの含有量は６質量％とした以外は同様にして試験を行った。
(Example 11)
A test was conducted in the same manner as in Example 8, except that the content of sulfamic acid in the acid solution was 12% by mass and the content of potassium hydroxide in the alkaline solution was 6% by mass.
（実施例１２）
実施例８で、酸溶液中のスルファミン酸の含有量を２質量％とし、アルカリ溶液中の水酸化カリウムの含有量は６質量％とした以外は同様にして試験を行った。
(Example 12)
A test was conducted in the same manner as in Example 8, except that the content of sulfamic acid in the acid solution was 2% by mass and the content of potassium hydroxide in the alkaline solution was 6% by mass.
（実施例１３）
実施例１で、酸溶液としてスルファミン酸に代えてメタンスルホン酸を用いた以外は同様にして試験を行った。
(Example 13)
A test was conducted in the same manner as in Example 1 except that methanesulfonic acid was used as the acid solution instead of sulfamic acid.
（実施例１４）
実施例８で、酸溶液としてスルファミン酸に代えてメタンスルホン酸を用いた以外は同様にして試験を行った。
(Example 14)
In Example 8, the test was conducted in the same manner except that methanesulfonic acid was used in place of sulfamic acid as the acid solution.
（実施例１５）
実施例１で、酸溶液としてスルファミン酸に代えてグリコール酸を用いた以外は同様にして試験を行った。
(Example 15)
The test was conducted in the same manner as in Example 1 except that glycolic acid was used as the acid solution instead of sulfamic acid.
（実施例１６）
実施例８で、酸溶液としてスルファミン酸に代えてグリコール酸を用いた以外は同様にして試験を行った。
(Example 16)
The test was conducted in the same manner as in Example 8 except that glycolic acid was used as the acid solution instead of sulfamic acid.
（実施例１７）
実施例８で、アルカリ溶液として水酸化カリウムに代えて水酸化ナトリウムを用いた以外は同様にして試験を行った。
(Example 17)
The test was conducted in the same manner as in Example 8 except that sodium hydroxide was used instead of potassium hydroxide as the alkaline solution.
（実施例１８）
実施例８で、アルカリ溶液（中に水酸化カリウム６質量％含有）に沈殿防止剤としてＥＤＴＡを１質量％含有させた以外は同様にして試験を行った。
(Example 18)
A test was conducted in the same manner as in Example 8 except that 1% by mass of EDTA was contained as an anti-precipitation agent in the alkaline solution (containing 6% by mass of potassium hydroxide therein).
（実施例１９）
実施例１で酸溶液（スルファミン酸８質量％含有）に洗浄性向上剤としてＥＤＴＡを１質量％含有させた以外は同様にして試験を行った。
(Example 19)
A test was conducted in the same manner as in Example 1 except that 1% by mass of EDTA was contained in the acid solution (containing 8% by mass of sulfamic acid) as a detergency improver.
（比較例１）
実施例１と同様に仮設循環回路を設置し、スルファミン酸の含有量が１０質量％に調整したスルファミン酸溶液を１２０分間循環させた後、フッ化水素アンモニウムの含有量が５質量％に調整したフッ化水素アンモニウム溶液を１２０分間循環させた。その後、洗浄液を排出し、浄水で洗浄した。各流体の温度は２０℃とした。
(Comparative Example 1)
A temporary circulation circuit was installed in the same manner as in Example 1, and after the sulfamic acid solution in which the content of sulfamic acid was adjusted to 10% by mass was circulated for 120 minutes, the content of ammonium hydrogen fluoride was adjusted to 5% by mass. The ammonium hydrogen fluoride solution was circulated for 120 minutes. Thereafter, the washing liquid was discharged and washed with purified water. The temperature of each fluid was 20 ° C.
（比較例２）
実施例１と同様に仮設循環回路を設置し、スルファミン酸の含有量が８質量％に調整したスルファミン酸溶液を１２０分間循環させた後、フッ化水素アンモニウムの含有量が３質量％に調整したフッ化水素アンモニウム溶液を１２０分間循環させた。その後、洗浄液を排出し、浄水で洗浄した。各流体の温度は２０℃とした。
(Comparative Example 2)
A temporary circulation circuit was installed in the same manner as in Example 1, and after the sulfamic acid solution in which the content of sulfamic acid was adjusted to 8% by mass was circulated for 120 minutes, the content of ammonium hydrogen fluoride was adjusted to 3% by mass. The ammonium hydrogen fluoride solution was circulated for 120 minutes. Thereafter, the washing liquid was discharged and washed with purified water. The temperature of each fluid was 20 ° C.
（比較例３）
実施例８と同様に仮設循環回路を設置し、スルファミン酸の含有量が１０質量％に調整したスルファミン酸溶液を１２０分間循環させた後、スルファミン酸溶液を排出し、水酸化カリウムの含有量が１０質量％に調整したアルカリ溶液を１２０分間循環させた。その後、洗浄液を排出し、浄水で洗浄した。各流体の温度は２０℃とした。
(Comparative Example 3)
In the same manner as in Example 8, a temporary circulation circuit was installed, and after the sulfamic acid solution in which the content of sulfamic acid was adjusted to 10% by mass was circulated for 120 minutes, the sulfamic acid solution was discharged and the content of potassium hydroxide was The alkaline solution adjusted to 10% by mass was circulated for 120 minutes. Thereafter, the washing liquid was discharged and washed with purified water. The temperature of each fluid was 20 ° C.
（比較例４）
実施例８と同様に仮設循環回路を設置し、スルファミン酸の含有量が８質量％に調整したスルファミン酸溶液を１２０分間循環させた後、スルファミン酸溶液を排出し、水酸化カリウムの含有量が６質量％に調整したアルカリ溶液を１２０分間循環させた。その後、洗浄液を排出し、浄水で洗浄した。各流体の温度は２０℃とした。
(Comparative Example 4)
In the same manner as in Example 8, a temporary circulation circuit was installed, and after the sulfamic acid solution in which the content of sulfamic acid was adjusted to 8% by mass was circulated for 120 minutes, the sulfamic acid solution was discharged and the content of potassium hydroxide was The alkaline solution adjusted to 6% by mass was circulated for 120 minutes. Thereafter, the washing liquid was discharged and washed with purified water. The temperature of each fluid was 20 ° C.
（比較例５）
実施例１と同様に仮設循環回路を設置し、メタンスルホン酸の含有量が１０質量％に調整したメタンスルホン酸溶液を１２０分間循環させた後、フッ化水素アンモニウムの含有量が５質量％に調整したフッ化水素アンモニウム溶液を１２０分間循環させた。その後、洗浄液を排出し、浄水で洗浄した。各流体の温度は２０℃とした。
(Comparative Example 5)
A temporary circulation circuit was installed in the same manner as in Example 1, and after the methanesulfonic acid solution in which the content of methanesulfonic acid was adjusted to 10% by mass was circulated for 120 minutes, the content of ammonium hydrogen fluoride was reduced to 5% by mass. The adjusted ammonium hydrogen fluoride solution was circulated for 120 minutes. Thereafter, the washing liquid was discharged and washed with purified water. The temperature of each fluid was 20 ° C.
（比較例６）
実施例８と同様に仮設循環回路を設置し、メタンスルホン酸の含有量が１０質量％に調整したメタンスルホン酸溶液を１２０分間循環させた後、メタンスルホン酸溶液を排出し、水酸化カリウムの含有量が１０質量％に調整したアルカリ溶液を１２０分間循環させた。その後、洗浄液を排出し、浄水で洗浄した。各流体の温度は２０℃とした。
(Comparative Example 6)
A temporary circulation circuit was installed in the same manner as in Example 8, and after the methanesulfonic acid solution in which the content of methanesulfonic acid was adjusted to 10% by mass was circulated for 120 minutes, the methanesulfonic acid solution was discharged, The alkaline solution whose content was adjusted to 10% by mass was circulated for 120 minutes. Thereafter, the washing liquid was discharged and washed with purified water. The temperature of each fluid was 20 ° C.
実施例１〜１９の評価結果を表１〜３に示し、比較例１〜６の評価結果を表４に示す。各表中の循環水中濃度は、各々の循環水で測定された酸濃度指標、フッ化物濃度指標、およびアルカリ濃度指標から算出された各成分の濃度を質量％で表示したものであり、経時での循環水中濃度は各溶液を追加前の濃度を示す。スケール状況は、洗浄後のスケール状況を洗浄前後の質量減少により５段階評価で示し、５（８０％〜１００％除去）、４（６０％〜８０％除去）、３（４０％〜６０％除去）、２（２０％〜４０％除去）、１（２０％以下）で評価した。 The evaluation results of Examples 1 to 19 are shown in Tables 1 to 3, and the evaluation results of Comparative Examples 1 to 6 are shown in Table 4. The circulating water concentration in each table is the concentration of each component calculated from the acid concentration index, the fluoride concentration index, and the alkali concentration index measured in each circulating water, expressed in mass%. The concentration in circulating water indicates the concentration before adding each solution. The scale status shows the scale status after cleaning with a five-step evaluation based on the decrease in mass before and after cleaning. 5 (80% to 100% removed), 4 (60% to 80% removed), 3 (40% to 60% removed) ), 2 (20% to 40% removal), 1 (20% or less).
表１〜表３に示すように、実施例１〜１９での洗浄により熱交換器に付着していたスケールはほぼ完全に除去されていた。特にアルカリ溶液に沈殿防止剤を含有させた実施例１８、および酸溶液に洗浄性向上剤を含有させた実施例１９での洗浄によりスケールは完全に除去されていた。これらに対して表４に示すように比較例１〜６ではスケールの除去は不完全であった。 As shown in Tables 1 to 3, the scale adhering to the heat exchanger was almost completely removed by washing in Examples 1 to 19. In particular, the scale was completely removed by washing in Example 18 in which a precipitation inhibitor was contained in an alkaline solution and in Example 19 in which a detergency improver was contained in the acid solution. On the other hand, as shown in Table 4, in Comparative Examples 1 to 6, scale removal was incomplete.
１ 仮設循環タンク
２ 仮設循環ポンプ
３ 仮設循環ライン
４ 流体用容器
４ａ 熱交換部材
４ｂ 熱交換器
５ 仮設循環回路
DESCRIPTION OF
Claims (14)
第一洗浄液を前記熱交換部材内又は流体用容器に流入、循環させ、定期的に循環水の第一洗浄液濃度指標を測定して該濃度指標の低下が実質停止するまで第一洗浄液を追加流入させて第一洗浄液濃度を制御することで前記熱交換部材に付着したスケールを膨潤又は剥落させ、
その後、第二洗浄液を、前記熱交換部材内又は流体用容器の循環水に流入、循環させながら、定期的に循環水の第二洗浄液濃度指標を測定して該濃度指標の低下が実質停止するまで第二洗浄液を追加流入させて第二洗浄液濃度を制御することで前記熱交換部材に付着したスケールを溶解除去することを特徴とする熱交換器の洗浄方法。 A heat exchanger cleaning method comprising a fluid container and a heat exchange member provided inside the fluid container,
The first cleaning liquid is allowed to flow into and circulate in the heat exchange member or the fluid container, and the first cleaning liquid concentration is periodically measured until the first cleaning liquid concentration index of the circulating water is measured and the decrease in the concentration index substantially stops. The scale attached to the heat exchange member is swollen or peeled off by controlling the first cleaning liquid concentration,
Thereafter, the second cleaning liquid is periodically flown into and circulated in the heat exchange member or in the fluid container, and the second cleaning liquid concentration index of the circulating water is periodically measured to substantially stop the decrease in the concentration index. A method of cleaning a heat exchanger, wherein the scale adhering to the heat exchange member is dissolved and removed by adding a second cleaning liquid until the second cleaning liquid is added to control the concentration of the second cleaning liquid.
その後、第二洗浄液としてアルカリ溶液を、前記熱交換部材内又は流体用容器に流入、循環させ、定期的に循環水のアルカリ濃度指標を測定してアルカリ濃度指標の低下が実質停止するまでアルカリ溶液を追加流入させてアルカリ濃度を制御することで前記熱交換部材に付着したスケールを溶解除去することを特徴とする請求項１に記載の熱交換器の洗浄方法。 The first cleaning liquid is an acid solution, and the acid solution is allowed to flow into and circulate in the heat exchange member or fluid container, and the acid concentration index of the circulating water is periodically measured to substantially reduce the acid concentration index. The acid solution is additionally introduced until it stops and the scale attached to the heat exchange member is swollen or peeled off by controlling the concentration, and then the acid solution is discharged from the heat exchange member or the fluid container,
Thereafter, an alkaline solution is introduced into the heat exchange member or the fluid container as a second cleaning liquid and circulated, and the alkali concentration index of the circulating water is periodically measured until the decrease in the alkali concentration index is substantially stopped. The heat exchanger cleaning method according to claim 1, wherein the scale adhering to the heat exchange member is dissolved and removed by adding an additional amount of alkali to control the alkali concentration.
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