JPS5948679B2 - How to prevent scale from adhering to heat exchangers, etc. - Google Patents
How to prevent scale from adhering to heat exchangers, etc.Info
- Publication number
- JPS5948679B2 JPS5948679B2 JP9801279A JP9801279A JPS5948679B2 JP S5948679 B2 JPS5948679 B2 JP S5948679B2 JP 9801279 A JP9801279 A JP 9801279A JP 9801279 A JP9801279 A JP 9801279A JP S5948679 B2 JPS5948679 B2 JP S5948679B2
- Authority
- JP
- Japan
- Prior art keywords
- hot water
- silicic acid
- amount
- heat
- geothermal hot
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 31
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 25
- 235000012239 silicon dioxide Nutrition 0.000 claims description 24
- 150000001875 compounds Chemical class 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- 239000000853 adhesive Substances 0.000 claims description 3
- 230000001070 adhesive effect Effects 0.000 claims description 3
- 239000000178 monomer Substances 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- 229940043430 calcium compound Drugs 0.000 claims 2
- 150000001674 calcium compounds Chemical class 0.000 claims 2
- 230000000717 retained effect Effects 0.000 claims 1
- 229920006395 saturated elastomer Polymers 0.000 claims 1
- 159000000007 calcium salts Chemical class 0.000 description 8
- 238000006116 polymerization reaction Methods 0.000 description 8
- 239000002253 acid Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical class [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- -1 Ca2+ compound Chemical class 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Landscapes
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Description
【発明の詳細な説明】
本発明は地熱熱水を有効利用するのに有効な熱交換器な
どへのスケール付着防止方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing scale adhesion to heat exchangers and the like, which is effective for effectively utilizing geothermal hot water.
一般に、地熱熱水にはヒ素などの有害成分が含まれてお
り、そのまま利用できるものは少ない。Generally, geothermal hot water contains harmful components such as arsenic, and there are few that can be used as is.
また、これらの有害成分を除去するためにはかなり高度
な水処理が必要となり、その際の放熱が大きいため実際
上不可能である。Furthermore, in order to remove these harmful components, a fairly sophisticated water treatment is required, which is practically impossible due to the large amount of heat released.
一方、清水や有機液体などの熱媒体と熱交換して地熱熱
水の保有する熱量を有効に利用しようとすると、地熱熱
水に含まれる硅酸が重合し、酸などによっても容易に溶
解しないスケールとなり、伝熱面や管壁に付着し、伝熱
効率を減少させるのみならず、配管の閉塞にまで至るこ
とがある。On the other hand, when attempting to effectively utilize the heat contained in geothermal hot water by exchanging heat with a heat medium such as fresh water or an organic liquid, the silicic acid contained in the geothermal hot water polymerizes and is not easily dissolved by acids. It becomes scale and adheres to heat transfer surfaces and pipe walls, reducing not only heat transfer efficiency but also clogging of pipes.
本発明は熱交換時において、難溶なスケールの生成を防
止し、地熱熱水の保有する熱量を最大限に利用できる方
法を提供するものである。The present invention provides a method that prevents the formation of refractory scale during heat exchange and makes maximum use of the amount of heat possessed by geothermal hot water.
発明者らは、すでに、熱交換器入口でＯａ 系化合物
を添加し、スケールの主因となる硅酸をカルシウム塩に
転換し、熱交換後、このカルシウム塩を除去するシステ
ムについて提案した。The inventors have already proposed a system in which an Oa-based compound is added at the inlet of a heat exchanger to convert silicic acid, which is the main cause of scale, into calcium salt, and this calcium salt is removed after heat exchange.
この発明は、これらのシステムにおいて、特に効果的で
かつ経済的なＣａ２＋系化合物の添加量を特定したもの
を提案するものである。This invention proposes a particularly effective and economical system in which the amount of Ca2+ compound added is specified.
地熱熱水を実験的に検討した結果、地熱熱水に含まれる
硅酸には、高分子化したゾル状態あるいはゲル状態の硅
酸と単量体硅酸とがあり、これらの硅酸を含んだ熱水を
熱交換して温度を下げると単量体硅酸としての溶解度が
下がり、過飽和の単量体硅酸が高分子状の硅酸をも架橋
するような状態で重合し、熱交換器などに付着し、強固
なスケールを生成することがわかった。As a result of experimental studies on geothermal hot water, we found that the silicic acid contained in geothermal hot water includes polymerized sol or gel silicic acid and monomeric silicic acid. When the temperature of hot water is lowered by heat exchange, the solubility of monomeric silicic acid decreases, and the supersaturated monomeric silicic acid polymerizes in such a way that it crosslinks polymeric silicic acid. It was found that it adheres to utensils, etc. and forms a strong scale.
したがって、単量体硅酸の重合を防止すれば、スケール
の生長を防止できることになる。Therefore, if the polymerization of monomeric silicic acid is prevented, scale growth can be prevented.
そこで、Ｃａ２＋系化合物を添加することによりこの硅
酸を付着性のないカルシウム塩へ転換する方法が考えら
れる。Therefore, a method of converting this silicic acid into a non-adhesive calcium salt by adding a Ca2+ type compound is considered.
そこで、この単量体硅酸を効率的にカルシウム塩に転換
する方法を検討した結果、単に化学量論的なＣａ２＋系
化合物を添加するのみではカルシウム塩に転換できず、
さらに０．００２〜０．００４ｍｏ ｌ ／１ の過剰
量の添加が最良であることが判明し本発明がなされたの
である。Therefore, as a result of investigating a method to efficiently convert this monomeric silicic acid into calcium salt, we found that it was not possible to convert it into calcium salt simply by adding a stoichiometric Ca2+-based compound.
Furthermore, it was found that it is best to add an excess amount of 0.002 to 0.004 mol/1, and the present invention was made based on this finding.
このように過剰のＣａ２＋系化合物の添加を要するのは
、高分子化した硅酸も１部Ｃａ２＋系化合物を消費する
ためと考えられる。The reason why it is necessary to add an excessive amount of Ca2+ type compound in this way is considered to be because polymerized silicic acid also partially consumes Ca2+ type compound.
Ｃａ２＋系化合物を大過剰に添加することにより、硅酸
をカルシウム塩に転換することは可能であるが、これに
よると高カルシウム含量の硅酸カルシウム塩が生成し、
熱水中の懸濁成分が増加し、これらが沈着などを起すた
め、かえって配管の閉塞などや熱交換器の伝熱性能の劣
化を生ぜしめ逆効果となる場合もある。Although it is possible to convert silicic acid into calcium salt by adding a large excess of Ca2+-based compounds, this produces calcium silicate salt with a high calcium content.
Suspended components in the hot water increase and cause deposition, which may even have the opposite effect, such as clogging pipes or deteriorating the heat transfer performance of the heat exchanger.
本発明でいうＣａ２＋系化合物とは、
Ｏａ （ＯＨ） ２ ・Ｏａ ０１２などの水中でＯａ
イオンを生ずる化合物をさし、これらを添加すると
同時に、酸またはアルカリを加えｐＨ調整などをするこ
ともできる。The Ca2+-based compound referred to in the present invention refers to Oa2+ compounds in water such as Oa (OH) 2 ・Oa 012.
Refers to compounds that generate ions, and at the same time as adding these compounds, it is also possible to adjust the pH by adding acid or alkali.
また本発明でいう化学量論量のＣａ２＋系化合物とは、
ＣａＯ／５ｉ０２が１である硫酸カルシウムを形成する
に必要なＣａ２＋系化合物の量をいう。In addition, the stoichiometric amount of Ca2+-based compound in the present invention is
It refers to the amount of Ca2+-based compounds required to form calcium sulfate where CaO/5i02 is 1.
本発明によれば、最も少量のＣａ２＋系化合物の添加で
最も少量の懸濁物質しか含まない状態でスケールの生成
を防止して熱交換ができる。According to the present invention, by adding the smallest amount of Ca2+ type compound, it is possible to perform heat exchange while preventing scale formation while containing only the smallest amount of suspended solids.
また、懸濁質である硅酸カルシウムはシリカスケールと
は異なって酸に可溶であり、沈着などした場合において
も洗浄が可能である。Furthermore, unlike silica scale, calcium silicate, which is a suspended substance, is soluble in acid, and even if it is deposited, it can be washed.
さらに、熱交換後に熱水に含まれるカルシウム塩を除去
すれば、この化合物と共に有害成分がかなり吸着除去さ
れることが予想され、放流あるいは農水産業などに利用
することも可能になる。Furthermore, if the calcium salts contained in the hot water are removed after heat exchange, it is expected that a considerable amount of harmful components will be adsorbed and removed along with these compounds, making it possible to discharge the water or use it in the agricultural and fisheries industries.
また、必要に応じて、この熱水に高度な水処理を行なっ
ても、熱交換後であるため熱損失は問題にならず、目的
に応じた水処理も可能となり、場合によれほこの処理水
を熱媒体として使用するシステムも可能となる。In addition, if necessary, even if this hot water is subjected to advanced water treatment, heat loss will not be a problem because it has been heat exchanged, and water treatment can be carried out according to the purpose. Systems that use water as a heat medium also become possible.
また、Ｃａ２＋系化合物の添加量を減少させて、さらに
経済性を高めるシステムとしてもう一つの発明がある。In addition, there is another invention as a system that further improves economic efficiency by reducing the amount of Ca2+-based compounds added.
すなわち、単量体硅酸の量を極力減少させた後Ｃａ２＋
系化合物を添加し熱交換する方法である。That is, after reducing the amount of monomeric silicic acid as much as possible, Ca2+
This method involves adding a system compound and exchanging heat.
ｐＨを５〜９に調整した地熱熱水を０．５〜３時間滞留
させると、さきにも述べたように、過飽和の硅酸が重合
するため単量体硅酸の量は熱交換器入口温度での飽和濃
度に近ずく。When geothermal hot water with a pH adjusted to 5 to 9 is allowed to stay for 0.5 to 3 hours, supersaturated silicic acid polymerizes, so the amount of monomeric silicic acid decreases at the inlet of the heat exchanger. Near saturation concentration at temperature.
したがって、滞留後Ｃａ２＋系化合物を熱交換器入口で
の単量体硅酸に対する化学量論量よりも０．００２〜０
．００４ｍｏｌ／Ｉ過剰量を添加することによって単量
体硅酸を完全にカルシウム塩に転換させ得る。Therefore, after residence, the Ca2+-based compound is 0.002 to 0.0
．． By adding an excess of 0.004 mol/I, the monomeric silicic acid can be completely converted to calcium salt.
そしてその添加量は大巾に減少されたものとなる場合が
多い。In many cases, the amount added is greatly reduced.
ここで、ｐＨを５〜９に、滞留時間を０．５〜３時間に
限定した理由について説明する。Here, the reason why the pH was limited to 5 to 9 and the residence time to 0.5 to 3 hours will be explained.
硅酸の水に対する溶解度は温度とｐＨに関係する。The solubility of silicic acid in water is related to temperature and pH.
温度が高いほど溶解度が高く、またｐＨが高くなるｃ！
＝（Ｈ２Ｃ１’）Ｓｉ（ＯＨ）５ＦＳｉ（ＯＨ）ｊ−な
ど（Ｄ陰イオンとして水中に存在することができ溶解度
が高くなる。The higher the temperature, the higher the solubility and the higher the pH c!
=(H2C1')Si(OH)5FSi(OH)j-, etc. (Can exist in water as a D anion and has high solubility.
すなわち硅酸は次式の反応によって水に溶解する。That is, silicic acid dissolves in water by the following reaction.
水中のｐＨが高いと、ＯＨ−イオン量が多いと次式のよ
うに解離するので溶解度がさらに増える。When the pH in water is high, the solubility further increases because a large amount of OH- ions dissociates as shown in the following equation.
ところで、単量体硅酸の重合反応（１）式の逆反応は、
ＯＨ−イオンを触媒として起こる反応であるから、ｐＨ
が低くＯＨ−イオンが少ないと重合しないのでｐＨを５
以上とし、またｐＨが高くなりすぎると、（２）及び（
３）式の解離が起こり、溶解度が大きくなって重合しな
くなるので、ｐＨを９以下とした。By the way, the reverse reaction of the polymerization reaction (1) of monomeric silicic acid is as follows:
Since the reaction occurs using OH- ions as a catalyst, the pH
If the pH is low and there are few OH- ions, polymerization will not occur, so the pH is set to 5.
above, and if the pH becomes too high, (2) and (
3) Since the dissociation of the formula occurs and the solubility increases and polymerization does not occur, the pH was set to 9 or less.
また滞留時間すなわち重合時間については、地熱水のｐ
Ｈや溶解物の量によって重合速度が異なるが、重合がほ
ぼ完了するためには０．５時間は必要と考えられ、また
３時間以上滞留させても重合しない硅酸であれば、熱交
換時にスケールとして重合することはないと考えられる
ため、上記のような時間範囲を設定した。Regarding the residence time, that is, the polymerization time, the geothermal water p
The polymerization rate varies depending on the amount of H and dissolved materials, but it is thought that 0.5 hours is necessary for the polymerization to be almost complete.Also, if silicic acid does not polymerize even after staying for more than 3 hours, Since it is thought that polymerization will not occur as a scale, the above time range was set.
なお、滞留槽はその構造を十分検討することによって、
滞留時間中の放熱を極力小さくすること困難でない。In addition, by carefully considering the structure of the retention tank,
It is not difficult to minimize heat radiation during the residence time.
また、この発明により、単量体硅酸を計測することなく
、熱交換入口温度によって、Ｃａ２一系化合物の添加量
をコントロールすることもできる。Further, according to the present invention, the amount of Ca2-based compound added can be controlled by the heat exchange inlet temperature without measuring monomer silicic acid.
以上の説明から明らかなように、本発明によれば地熱熱
水を熱源として有効利用することができ、その場合に、
熱交換器の伝熱面等に対するスケールの付着を防止し得
るものであり、加えて懸濁成分の発生も最小限に抑える
ことができる。As is clear from the above description, according to the present invention, geothermal hot water can be effectively used as a heat source, and in that case,
It is possible to prevent scale from adhering to the heat transfer surface of the heat exchanger, and in addition, the generation of suspended components can be minimized.
また懸濁物質が生成したとしてもこれは酸に可溶である
ため容易に洗浄が可能であり、伝熱性能を劣化せしめる
ことはない。Further, even if suspended matter is generated, it can be easily washed because it is soluble in acid, and the heat transfer performance will not be deteriorated.
さらに本発明において地熱熱水に添加するＣａ２一系物
質は必要かつ十分な量に限定されるので、経済的でもあ
る。Furthermore, in the present invention, the Ca2 type substance added to geothermal hot water is limited to a necessary and sufficient amount, so it is also economical.
Claims (1)
熱水中の単量体硅酸に対する化学量論量よりも０．００
２〜０．００４ ｍｏｌ／１過剰のＯａ 系化合物を
該地熱熱水に添加して、硅酸を非付着性のカルシウム化
合物として除去することを特徴とする熱交換器などへの
スケール付着防止方法。 ２ 地熱熱水との熱交換において、熱交換器入口で、地
熱熱水をｐＨ５〜９の範囲で０．５〜３時間滞留させ、
その後、熱交換器の入口温度における単量体硅酸の飽和
溶解量に対して化学量論量よりも０、 ＯＯ２〜０．０
０４ ｍｏｌ／１過剰のＣａ２＋系化合物を該地熱熱水
に添加して、硅酸を非付着性のカルシウム化合物として
除去することを特徴とする熱交換器などへのスケール付
着防止方法。[Claims] 1. In heat exchange with geothermal hot water, at the inlet of the heat exchanger, the amount of silica monomer in the geothermal hot water is 0.00% less than the stoichiometric amount.
A method for preventing scale adhesion to heat exchangers, etc., characterized by adding 2 to 0.004 mol/1 excess Oa-based compound to the geothermal hot water to remove silicic acid as a non-adhesive calcium compound. . 2. In heat exchange with geothermal hot water, geothermal hot water is retained at the inlet of the heat exchanger for 0.5 to 3 hours at a pH in the range of 5 to 9,
After that, the amount of saturated dissolved monomer silicic acid at the inlet temperature of the heat exchanger is less than the stoichiometric amount, and OO2~0.0.
04 A method for preventing scale adhesion to a heat exchanger or the like, which comprises adding a mol/1 excess of a Ca2+-based compound to the geothermal hot water to remove silicic acid as a non-adhesive calcium compound.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9801279A JPS5948679B2 (en) | 1979-07-31 | 1979-07-31 | How to prevent scale from adhering to heat exchangers, etc. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9801279A JPS5948679B2 (en) | 1979-07-31 | 1979-07-31 | How to prevent scale from adhering to heat exchangers, etc. |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5621696A JPS5621696A (en) | 1981-02-28 |
| JPS5948679B2 true JPS5948679B2 (en) | 1984-11-28 |
Family
ID=14207877
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9801279A Expired JPS5948679B2 (en) | 1979-07-31 | 1979-07-31 | How to prevent scale from adhering to heat exchangers, etc. |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5948679B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6097186U (en) * | 1983-12-08 | 1985-07-02 | スミダ紙工株式会社 | Inlaid paint for sales promotion |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53145265A (en) * | 1977-05-20 | 1978-12-18 | Toshiba Corp | Pulverulent body feeder |
-
1979
- 1979-07-31 JP JP9801279A patent/JPS5948679B2/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6097186U (en) * | 1983-12-08 | 1985-07-02 | スミダ紙工株式会社 | Inlaid paint for sales promotion |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5621696A (en) | 1981-02-28 |
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