JPH0775641B2 - Method and apparatus for evaporating aqueous solution containing water-soluble solute whose saturated solubility in water is inversely proportional to temperature - Google Patents
Method and apparatus for evaporating aqueous solution containing water-soluble solute whose saturated solubility in water is inversely proportional to temperatureInfo
- Publication number
- JPH0775641B2 JPH0775641B2 JP10150391A JP10150391A JPH0775641B2 JP H0775641 B2 JPH0775641 B2 JP H0775641B2 JP 10150391 A JP10150391 A JP 10150391A JP 10150391 A JP10150391 A JP 10150391A JP H0775641 B2 JPH0775641 B2 JP H0775641B2
- Authority
- JP
- Japan
- Prior art keywords
- aqueous solution
- water
- evaporator
- heater
- temperature
- 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 - Fee Related
Links
- 239000007864 aqueous solution Substances 0.000 title claims description 67
- 238000001704 evaporation Methods 0.000 title claims description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 17
- 229920006395 saturated elastomer Polymers 0.000 title claims description 15
- 238000000034 method Methods 0.000 title claims description 6
- 239000013078 crystal Substances 0.000 claims description 36
- 230000008020 evaporation Effects 0.000 claims description 24
- 238000001556 precipitation Methods 0.000 claims description 19
- 238000010438 heat treatment Methods 0.000 claims description 17
- 239000007788 liquid Substances 0.000 claims description 16
- 238000002156 mixing Methods 0.000 claims description 15
- 238000011144 upstream manufacturing Methods 0.000 claims description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 72
- 229940099596 manganese sulfate Drugs 0.000 description 4
- 239000011702 manganese sulphate Substances 0.000 description 4
- 235000007079 manganese sulphate Nutrition 0.000 description 4
- SQQMAOCOWKFBNP-UHFFFAOYSA-L manganese(II) sulfate Chemical compound [Mn+2].[O-]S([O-])(=O)=O SQQMAOCOWKFBNP-UHFFFAOYSA-L 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000006228 supernatant Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003809 water extraction Methods 0.000 description 1
Landscapes
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、硫酸カルシウム（Ｃａ
ＳＯ4 ・１／２Ｈ2 Ｏ）又は硫酸マンガン（ＭｎＳＯ4
・Ｈ2 Ｏ）等のように、水に対する飽和溶解度が温度の
上昇に反比例する水溶性溶質を含む水溶液を、当該水溶
液中の水を加熱蒸発するようにした蒸発方法、及びその
装置に関するものである。The present invention relates to calcium sulfate (Ca
SO 4 · 1 / 2H 2 O) or manganese sulfate (MnSO 4
· H 2 O) as such, an aqueous solution containing a water-soluble solute saturation solubility in water is inversely proportional to the increase in temperature, but the evaporation method to heat evaporates the water in the aqueous solution, and to a device is there.
【０００２】[0002]
【従来の技術】水溶性溶質を含む水溶液中の水を加熱蒸
発するには、例えば、丸善株式会社、昭和５０年５月３
０日第２版発行の「化学装置便覧」等に記載されている
ように、自然循環型蒸発装置又は強制循環型蒸発装置等
のような各種形式の減圧式蒸発装置を使用するのが、一
般的であった。2. Description of the Related Art To heat and evaporate water in an aqueous solution containing a water-soluble solute, see, for example, Maruzen Co., Ltd., May 3, 1975.
Generally, it is common to use various types of decompression type evaporators such as a natural circulation type evaporator or a forced circulation type evaporator as described in "Chemical Equipment Handbook" issued on the 2nd edition of 0th day. It was target.
【０００３】そして、これらの減圧式蒸発装置は、従来
から良く知られているように、水溶液を、間接熱交換式
の加熱器にて加熱したのち、大気圧以下の減圧状態に保
持された蒸発缶内で蒸発し、この蒸発した後の水溶液
を、前記加熱器で再び加熱すると言う循環を行なわせ
て、前記水溶液の中を水を加熱蒸発するものである。As is well known in the art, these depressurization type evaporators evaporate an aqueous solution heated by an indirect heat exchange type heater and then kept at a reduced pressure below atmospheric pressure. The water in the aqueous solution is evaporated by heating in the can by circulating the aqueous solution after the evaporation by reheating with the heater.
【０００４】[0004]
【発明が解決しようとする課題】前記減圧式蒸発装置
は、水溶液を間接的に加熱するための加熱器を必要とす
るものであるから、蒸発しようとする水溶液が、水溶性
溶質として硫酸カルシウム、又は硫酸マンガンを含むも
のであって、この水溶液を、その溶質が結晶として析出
する状態まで蒸発する場合には、以下に述べるような問
題を招来する。Since the decompression-type evaporator requires a heater for indirectly heating the aqueous solution, the aqueous solution to be evaporated contains calcium sulfate as a water-soluble solute, Alternatively, when manganese sulfate is contained and the aqueous solution is evaporated to a state where the solute is deposited as crystals, the following problems are brought about.
【０００５】すなわち、前記硫酸カルシウムの水に対す
る飽和溶解度（飽和水溶液１００ｇ中に含まれる溶質の
重量）は、温度の上昇に伴って下がると言うように温度
に反比例するものであり、換言すると、この硫酸カルシ
ウム水溶液の飽和溶解度曲線は、図３に示すように右下
がりの曲線であって、この硫酸カルシウムを含む水溶液
を、前記減圧式蒸発装置によって硫酸カルシウムの結晶
が析出する状態まで加熱蒸発するに際しては、その加熱
器での加熱中において、当該硫酸カルシウム水溶液は、
前記飽和溶解度曲線より下側の未飽和領域から当該飽和
溶解度曲線を越えてその上側の過飽和領域に大きく移行
して高い過飽和状態になり、その結果、前記加熱器にお
ける両伝熱面のうち前記硫酸カルシウム水溶液が接触す
る側の伝熱面に、前記硫酸カルシウム水溶液中の硫酸カ
ルシウムの結晶が析出してスケールとなって付着するか
ら、加熱蒸発の運転を停止して、加熱器に発生するスケ
ールを除去することを頻繁に行うようにしなければなら
ないばかりか、スケールの付着が著しい場合には、加熱
器における伝熱管の損傷が発生すると言う問題があっ
た。That is, the saturated solubility of calcium sulfate in water (the weight of the solute contained in 100 g of the saturated aqueous solution) is inversely proportional to the temperature, that is, it decreases as the temperature rises. The saturated solubility curve of the calcium sulfate aqueous solution is a downward-sloping curve as shown in FIG. 3, and when the aqueous solution containing calcium sulfate is heated and evaporated by the decompression-type evaporator to a state where calcium sulfate crystals are precipitated. During heating in the heater, the calcium sulfate aqueous solution,
From the unsaturated region below the saturated solubility curve to the supersaturated region above the saturated solubility curve, the supersaturated state is largely shifted to a high supersaturated state, and as a result, the sulfuric acid in both heat transfer surfaces of the heater is increased. On the heat transfer surface on the side in contact with the calcium aqueous solution, the crystals of calcium sulfate in the calcium sulfate aqueous solution are deposited and adhere as a scale, so the heating evaporation operation is stopped and the scale generated in the heater is adjusted. In addition to having to be frequently removed, there is a problem that the heat transfer tube in the heater may be damaged if the scale adheres significantly.
【０００６】また、硫酸マンガンの水に対する飽和溶解
度も、前記硫酸カルシウムの場合と同様に、温度に反比
例するものであるから、これらの水溶液を結晶が析出す
る状態まで加熱蒸発する場合においても、前記と同様の
問題が発生するのである。本発明は、前記硫酸カルシウ
ム、又は硫酸マンガン等のように、水に対する飽和溶解
度が温度に反比例する水溶性溶質を含む水溶液を、溶質
の結晶が析出する状態まで加熱・蒸発するに際して、加
熱器における伝熱管にスケールが発生することを確実に
低減できるようにした方法、及びその方法に使用する装
置を提供することを技術的課題とするものである。Also, the saturation solubility of manganese sulfate in water is inversely proportional to the temperature as in the case of calcium sulfate, and therefore, even when these aqueous solutions are heated and evaporated to a state where crystals are precipitated, The same problem occurs. The present invention, in the case of heating and evaporating an aqueous solution containing a water-soluble solute whose saturation solubility in water is inversely proportional to temperature, such as the above-mentioned calcium sulfate or manganese sulfate, in a heater It is a technical object to provide a method capable of reliably reducing generation of scale in a heat transfer tube, and an apparatus used for the method.
【０００７】[0007]
【課題を解決するための手段】この技術的課題を達成す
るため本発明の方法は、「水に対する飽和溶解度が温度
の上昇に反比例する水溶性溶質を含む水溶液を、間接熱
交換式の加熱器にて加熱し、大気圧以下の減圧状態に保
持された蒸発缶内で蒸発するようにした蒸発方法におい
て、前記蒸発缶で蒸発した後の水溶液に、熱源としての
蒸気を混合し、前記水溶性溶質の結晶を析出してその結
晶を分離・除去し、次いで、大気圧以下の減圧状態でフ
ラッシュ蒸発したのち、前記加熱器にて加熱する循環を
行う。」ことを特徴とするものである。In order to achieve this technical object, the method of the present invention is "an indirect heat exchange type heater for an aqueous solution containing a water-soluble solute whose saturated solubility in water is inversely proportional to an increase in temperature. In the evaporation method of heating in, and evaporating in an evaporator held under reduced pressure below atmospheric pressure, the aqueous solution after evaporation in the evaporator is mixed with steam as a heat source, A solute crystal is deposited, the crystal is separated and removed, and then flash evaporation is performed under a reduced pressure condition of atmospheric pressure or less, followed by circulation by heating with the heater. "
【０００８】また、本発明の装置は、「大気圧以下の減
圧状態に保持した蒸発缶と、多数本の伝熱管を備えた加
熱器と、水に対する飽和溶解度が温度の上昇に反比例す
る水溶性溶質を含む水溶液を前記蒸発缶と加熱器との間
を循環するようにした循環経路とから成る蒸発装置にお
いて、前記循環経路のうち前記蒸発缶から加熱器に至る
部分に、前記水溶液に対して熱源としての蒸気を混合す
る気液混合部と、大気圧以下の減圧状態に保持したフラ
ッシュ蒸発部とを、前記気液混合部を上流側にフラッシ
ュ蒸発部を下流側にして設け、更に、前記循環経路のう
ち前記気液混合部とフラッシュ蒸発部との間の部位に、
結晶析出タンクを設ける。」と言う構成にした。Further, the apparatus of the present invention includes: an evaporator that is kept at a reduced pressure below atmospheric pressure, a heater provided with a large number of heat transfer tubes, and a water-soluble solution whose saturation solubility in water is inversely proportional to the increase in temperature. In an evaporator comprising a circulation path adapted to circulate an aqueous solution containing a solute between the evaporator and the heater, a part of the circulation path from the evaporator to the heater is provided with respect to the aqueous solution. A gas-liquid mixing section that mixes steam as a heat source, and a flash evaporation section that is maintained at a reduced pressure below atmospheric pressure are provided with the gas-liquid mixing section on the upstream side and the flash evaporation section on the downstream side. At a portion of the circulation path between the gas-liquid mixing section and the flash evaporation section,
Provide a crystal precipitation tank. "."
【０００９】[0009]
【作用】このように、加熱器で加熱し、次いで、蒸発缶
で蒸発した後の水溶液に、ボイラー等からの高い温度の
蒸気を、気液混合部において混合すると、前記水溶液の
温度が上昇して、当該水溶液は、飽和溶解度曲線よりも
上側の過飽和領域内における高い過飽和状態になること
により、この水溶液中の水溶性溶質は、結晶として析出
するから、当該水溶液の濃度は、飽和溶解度に近い状態
になる。As described above, when the high temperature steam from the boiler or the like is mixed with the aqueous solution after being heated by the heater and then evaporated by the evaporator, the temperature of the aqueous solution rises. Then, since the aqueous solution becomes a high supersaturated state in the supersaturation region above the saturation solubility curve, the water-soluble solute in this aqueous solution is precipitated as crystals, so the concentration of the aqueous solution is close to the saturated solubility. It becomes a state.
【００１０】次いで、この水溶液を、当該水溶液中の結
晶を分離・除去したのち、大気圧以下の減圧状態のフラ
ッシュ蒸発部においてフラッシュ蒸発すると、この水溶
液の温度が下がることにより、当該水溶液を、一旦、飽
和溶解度曲線よりも下側の未飽和領域内に大きく入り込
むように可成り低い未飽和状態にすることができ、換言
すると、前記加熱器による水溶液の加熱を、可成り低い
未飽和の状態から開始することができるから、この加熱
器での加熱中において、前記水溶液が、前記飽和溶解度
曲線を越えて過飽和領域に入ることを防止できるか、或
いは、過飽和領域に入る程度を大幅に下げることができ
るのである。Then, after the crystals in the aqueous solution are separated and removed, the aqueous solution is flash-evaporated in a flash evaporation section under a reduced pressure below atmospheric pressure, and the temperature of the aqueous solution is lowered. , It is possible to make a considerably low unsaturated state so as to largely enter into the unsaturated region below the saturated solubility curve, in other words, heating the aqueous solution by the heater from a considerably low unsaturated state. Since it can be started, it is possible to prevent the aqueous solution from entering the supersaturation region beyond the saturation solubility curve during heating with this heater, or to significantly reduce the degree of entering the supersaturation region. You can do it.
【００１１】[0011]
【発明の効果】従って、本発明によると、水に対する飽
和溶解度が温度の上昇に反比例する水溶性溶質を含む水
溶液を、溶質の結晶が析出する状態まで加熱・蒸発する
に際して、この水溶液を、加熱器で加熱する途中におい
て、当該水溶液が、飽和溶解度曲線を越えて過飽和状態
になることを防止できるか、或いは、過飽和状態になる
程度を大幅に下げることができるから、前記加熱器にお
ける伝熱面に、水溶液中の水溶性溶質がスケールとして
析出すること、換言すると、前記加熱器における各伝熱
管にスケールが発生することを確実に低減でき、その結
果、加熱・蒸発の運転時間を大幅に延長することができ
ると共に、加熱器における各伝熱管に損傷が発生するこ
とも確実に低減できる効果を有する。Therefore, according to the present invention, when an aqueous solution containing a water-soluble solute whose saturated solubility in water is inversely proportional to the increase in temperature is heated and evaporated until a crystal of the solute is precipitated, the aqueous solution is heated. In the middle of heating with a heating device, the aqueous solution can be prevented from exceeding the saturation solubility curve and becoming a supersaturated state, or the degree of becoming a supersaturated state can be significantly reduced. In addition, it is possible to reliably reduce the precipitation of the water-soluble solute in the aqueous solution as a scale, in other words, to prevent the scale from being generated in each heat transfer tube in the heater, and as a result, the operating time of heating and evaporation can be significantly extended. In addition to the above, it is possible to reliably reduce the occurrence of damage to each heat transfer tube in the heater.
【００１２】[0012]
【実施例】以下、本発明の実施例を、自己蒸気圧縮型の
蒸発装置にて硫酸カルシウム水溶液を硫酸カルシウムの
結晶が析出する状態まで蒸発することに適用した場合の
図面（図１）について説明する。図において符号１は、
密閉型の蒸発缶を示し、該蒸発缶１内の上部には、左右
一対のヘッダー２ａ，２ｂと、この両ヘッダー２ａ，２
ｂの間を繋ぐ複数本の伝熱管２ｃとから成る加熱器２が
設けられている。Embodiments of the present invention will now be described with reference to the drawing (FIG. 1) in the case where the present invention is applied to evaporating an aqueous solution of calcium sulfate to a state in which calcium sulfate crystals are precipitated in a self-vapor compression type evaporator. To do. In the figure, reference numeral 1 is
A closed-type evaporator is shown, and a pair of left and right headers 2a and 2b and both headers 2a and 2 are provided in the upper part of the evaporator 1.
A heater 2 including a plurality of heat transfer tubes 2c connecting between b is provided.
【００１３】符号３は、管路４より供給される冷却水に
よって冷却するようにした凝縮器を示し、この凝縮器３
には、前記蒸発缶１における蒸気出口５からの蒸気ダク
ト６が接続されていると共に、前記蒸発缶１内を大気圧
以下の減圧状態に保持するための真空ポンプ７等の真空
発生装置が接続され、且つ、凝縮水の排出ポンプ８が接
続され、更に、前記加熱器２における他方のヘッダー２
ｂからの凝縮水抽出管路９が接続されている。なお、前
記蒸気ダクト６又は凝縮器３には、前記加熱器２におけ
る他方のヘッダー２ｂからの不凝縮性ガスの抽出管路１
０が接続されている。Reference numeral 3 indicates a condenser which is cooled by the cooling water supplied from the pipe 4, and the condenser 3
Is connected to a steam duct 6 from a steam outlet 5 of the evaporator 1, and is connected to a vacuum generator such as a vacuum pump 7 for maintaining the inside of the evaporator 1 at a reduced pressure below atmospheric pressure. And a discharge pump 8 for the condensed water is connected, and the other header 2 in the heater 2 is further connected.
The condensed water extraction line 9 from b is connected. It should be noted that the steam duct 6 or the condenser 3 has an extraction conduit 1 for extracting the non-condensable gas from the other header 2b of the heater 2.
0 is connected.
【００１４】前記蒸発缶１から前記凝縮器３への蒸気ダ
クト６内を流れる蒸気の一部を、ボイラー（図示せず）
から蒸気供給管路１１より供給の高圧蒸気にて駆動され
る蒸気エゼクター１２によって吸引・圧縮したのち、蒸
気ダクト１３を介して前記加熱器２における一方のヘッ
ダー２ａ内に供給する。一方、前記蒸発缶１内の底部に
おける硫酸カルシウム水溶液を、第１循環管路１４を介
して結晶析出タンク１５内に導いたのち、この結晶析出
タンク１５内における上部から上澄液として抽出し、こ
れを循環ポンプ１６及び第２循環管路１７を介して、前
記蒸発缶１内の上部に設けたノズル１８に送って、この
ノズル１８から前記加熱器２における各伝熱管２ｃの外
表面に向かって散布する循環を行うように構成する一
方、前記第２循環管路１７の途中に、硫酸カルシウム水
溶液を管路１９より供給する。A part of the steam flowing in the steam duct 6 from the evaporator 1 to the condenser 3 is replaced by a boiler (not shown).
After being sucked and compressed by the steam ejector 12 driven by the high-pressure steam supplied from the steam supply pipe 11, the steam is supplied into the one header 2a of the heater 2 through the steam duct 13. On the other hand, after introducing the calcium sulfate aqueous solution at the bottom of the evaporator 1 into the crystal precipitation tank 15 via the first circulation line 14, it is extracted as a supernatant from the upper part of the crystal precipitation tank 15. This is sent via a circulation pump 16 and a second circulation pipe line 17 to a nozzle 18 provided in the upper part of the evaporator 1 and directed from the nozzle 18 to the outer surface of each heat transfer pipe 2c in the heater 2. On the other hand, the calcium sulfate aqueous solution is supplied from a conduit 19 in the middle of the second circulation conduit 17 while the circulation is performed by spraying.
【００１５】そして、前記第１循環管路１４の途中に
は、気液混合部２０を設ける一方、前記蒸気エゼクター
１２から一方のヘッダー２ａへの蒸気ダクト１３内を流
れる蒸気の一部を、熱源として取り出し、これを前記蒸
気供給管路１１より供給の高圧蒸気にて駆動される補助
蒸気エゼクター２１によって吸引・圧縮したのち、蒸気
ダクト２２を介して前記気液混合部２０に導いて、前記
蒸発缶１から結晶析出タンク１５内への硫酸カルシウム
水溶液に対して直接的に混合するようにする。A gas-liquid mixing section 20 is provided in the middle of the first circulation line 14, while a part of the steam flowing in the steam duct 13 from the steam ejector 12 to the header 2a is partially heated. And sucked and compressed by an auxiliary steam ejector 21 driven by high-pressure steam supplied from the steam supply pipeline 11, and then guided to the gas-liquid mixing section 20 via a steam duct 22 to carry out the evaporation. The calcium sulfate aqueous solution from the can 1 into the crystal precipitation tank 15 is directly mixed.
【００１６】この構成において、蒸発缶１内の底部にお
ける硫酸カルシウム水溶液は、第１循環管路１４を介し
て結晶析出タンク１５内に導かれる途中の気液混合部２
０において、熱源としての蒸気が混合されることによっ
て、濃度が少し低くなりながら温度が高くなって、結晶
析出タンク１５内に流入する。そして、この結晶析出タ
ンク１５内に流入した硫酸カルシウム水溶液は、当該結
晶析出タンク１５から上澄液として循環ポンプ１６にて
汲み出され、第２循環管路１７を経てノズル１８から蒸
発缶１内に噴出するときフラッシュ蒸発することによ
り、濃度が少し高くなりながら蒸発缶１内における蒸気
の温度と等しい温度まで下がり、次いで、加熱器２にお
ける各伝熱管２ｃの外表面に接触することにより、加熱
・蒸発されると言う循環を繰り返すのである。In this structure, the aqueous solution of calcium sulfate at the bottom of the evaporator 1 is introduced into the crystal precipitation tank 15 via the first circulation line 14, and the gas-liquid mixing section 2 is in the process of being introduced.
At 0, the vapor is mixed as a heat source, so that the temperature rises while the concentration is slightly lowered, and the vapor flows into the crystal precipitation tank 15. Then, the calcium sulfate aqueous solution that has flowed into the crystal precipitation tank 15 is pumped out from the crystal precipitation tank 15 as a supernatant liquid by the circulation pump 16, and passes through the second circulation pipe line 17 from the nozzle 18 to the inside of the evaporator 1. When it is jetted to the flash, it flash-evaporates and its concentration decreases to a temperature equal to the temperature of the vapor in the evaporator 1 while increasing slightly, and then it contacts the outer surface of each heat transfer tube 2c in the heater 2 to heat it.・ The cycle of being vaporized is repeated.
【００１７】この装置において、前記蒸発缶１内におけ
る蒸気の温度を７０℃に設定する一方、硫酸カルシウム
水溶液の沸点上昇が例えば約５℃であると仮定すると、
この蒸発缶１の底部から流出する硫酸カルシウム水溶液
の温度は７５℃になる。また、この硫酸カルシウム水溶
液に前記気液混合部２０において蒸気を混合することに
よって、当該硫酸カルシウム水溶液の温度を８０℃まで
上昇するものとすると、この硫酸カルシウム水溶液は、
前記蒸発缶１内にノズル１８から噴出するときのフラッ
シュ蒸発により、その温度が、前記蒸発缶１内の蒸気の
温度７０に沸点上昇５℃を加えた７５℃の温度に下がる
ことになる。In this apparatus, assuming that the temperature of the steam in the evaporator 1 is set to 70 ° C. and the boiling point of the calcium sulfate aqueous solution rises by about 5 ° C.,
The temperature of the aqueous solution of calcium sulfate flowing out from the bottom of the evaporator 1 is 75 ° C. Further, if the temperature of the calcium sulfate aqueous solution is raised to 80 ° C. by mixing the calcium sulfate aqueous solution with steam in the gas-liquid mixing section 20, the calcium sulfate aqueous solution is
The flash evaporation when the gas is ejected from the nozzle 18 into the evaporator 1 reduces its temperature to 75 ° C., which is the temperature 70 of the vapor in the evaporator 1 plus the boiling point increase 5 ° C.
【００１８】そこで、前記蒸発缶１の底部から流出する
硫酸カルシウム水溶液の濃度を、温度が７５℃における
飽和溶解度０．１１３（ｗｔ％）と略等しい値、つま
り、図３においてＡ点に設定すると、この硫酸カルシウ
ム水溶液は、前記気液混合部２０における蒸気の混合に
より、その濃度が若干低くなりつつ温度が８０℃まで上
昇することにより、図３に示すように、蒸発缶１から出
るときのＡ点の状態からから熱源としての蒸気の混合に
よってＢ点の状態に移行して、飽和溶解度曲線よりも上
側の過飽和領域内における高い過飽和状態になるから、
この硫酸カルシウム水溶液中の硫酸カルシウムは、前記
結晶析出タンク１５内において結晶として析出して、当
該結晶析出タンク１５内の底部に沈澱・分離する。Therefore, if the concentration of the calcium sulfate aqueous solution flowing out from the bottom of the evaporator 1 is set to a value approximately equal to the saturation solubility of 0.113 (wt%) at a temperature of 75 ° C., that is, at point A in FIG. As the calcium sulfate aqueous solution is mixed with the vapor in the gas-liquid mixing section 20, the temperature thereof rises to 80 ° C. while the concentration thereof is slightly lowered, so that the aqueous solution of the calcium carbonate when it is discharged from the evaporator 1 as shown in FIG. Since the state of point A shifts to the state of point B by mixing steam as a heat source, the state becomes a high supersaturation state in the supersaturation region above the saturation solubility curve,
The calcium sulfate in the calcium sulfate aqueous solution is precipitated as crystals in the crystal precipitation tank 15, and is precipitated and separated at the bottom of the crystal precipitation tank 15.
【００１９】この結晶の析出によって、この結晶析出タ
ンク１５より流出する硫酸カルシウム水溶液の濃度は、
８０℃における略飽和溶解度０．１０１（ｗｔ％）まで
下がって、図３におけるＣ点の状態になる。次いで、こ
のＣ点の状態の硫酸カルシウム水溶液は、蒸発缶１内に
ノズル１８から噴出するときフラッシュ蒸発して、濃度
が少し上昇しつつ温度が７５℃まで下がることにより、
結晶析出タンク１５を出るときのＣ点の状態からフラッ
シュ蒸発によってＤ点の状態に移行するから、硫酸カル
シウム水溶液を加熱器２にて加熱する前の状態におい
て、当該硫酸カルシウム水溶液を、一旦、飽和溶解度曲
線よりも下側の未飽和領域内に大きく入り込むように可
成り低い未飽和状態にすることができ、この可成り低い
未飽和状態のＤ点から前記Ａ点まで加熱・蒸発されるの
である。Due to the precipitation of the crystals, the concentration of the calcium sulfate aqueous solution flowing out from the crystal precipitation tank 15 is
The saturated solubility at 80 ° C. is lowered to 0.101 (wt%), and the state becomes point C in FIG. Next, the calcium sulfate aqueous solution in the state of point C undergoes flash evaporation when ejected from the nozzle 18 into the evaporator 1, and the temperature decreases to 75 ° C. while the concentration slightly increases,
Since the state of point C when leaving the crystal precipitation tank 15 is changed to the state of point D by flash evaporation, the calcium sulfate aqueous solution is once saturated in the state before the calcium sulfate aqueous solution is heated by the heater 2. The unsaturated state can be set to a considerably low unsaturated state so as to largely enter the unsaturated region below the solubility curve, and heating and evaporation are performed from point D to point A in the unsaturated state that is considerably low. .
【００２０】すなわち、前記加熱器２にて加熱する前に
おいて、硫酸カルシウム水溶液を、硫酸カルシウム結晶
化及びフラッシュ蒸発によって一旦、可成り低い未飽和
の状態にすることができ、この可成り低い未飽和の状態
から前記加熱器２による加熱を開始するものであるか
ら、この加熱器２での加熱中において、前記硫酸カルシ
ウム水溶液が、前記飽和溶解度曲線を越えて過飽和領域
に入ることを防止できるか、或いは、過飽和領域に入る
程度を大幅に下げることができるのである。That is, before heating with the heater 2, the calcium sulfate aqueous solution can be once brought into a considerably low unsaturated state by calcium sulfate crystallization and flash evaporation. Since heating by the heater 2 is started from this state, it is possible to prevent the aqueous solution of calcium sulfate from exceeding the saturated solubility curve and entering the supersaturated region during heating by the heater 2. Alternatively, the degree of entering the supersaturation region can be significantly reduced.
【００２１】前記結晶析出タンク１５内の底部に沈澱し
た結晶は、スラリーポンプ２３にて遠心分離機２４に送
って、この遠心分離機２４にて液分を分離したのち取り
出される一方、この結晶から分離されてタンク２５に溜
まった硫酸カルシウム水溶液は、ポンプ２７付き管路２
６を介して、前記第２循環管路１７内に戻されるのであ
る。このスラリーポンプ２３には、当該スラリーポンプ
２３から吐出液の一部を、前記結晶析出タンク１５内に
おける前記スラリーポンプ２３への吸い込み部に戻すこ
とによって、結晶の抽出を容易にするためのバイパス管
路２８が設けられている。The crystals precipitated at the bottom of the crystal precipitation tank 15 are sent to the centrifugal separator 24 by the slurry pump 23, and the liquid is separated after being separated by the centrifugal separator 24, while the crystals are taken out from the crystals. The aqueous solution of calcium sulfate that has been separated and accumulated in the tank 25 is connected to the pipeline 2 with the pump 27.
It is returned to the inside of the second circulation conduit 17 via 6. The slurry pump 23 has a bypass pipe for facilitating the extraction of crystals by returning a part of the liquid discharged from the slurry pump 23 to the suction part in the crystal precipitation tank 15 to the slurry pump 23. A path 28 is provided.
【００２２】なお、前記実施例は、蒸発缶１内に加熱器
２を設ける一方、循環する水溶液を、前記蒸発缶１内に
設けたノズル１８から前記加熱器２における伝熱管２ｃ
に対して噴出することにより、前記循環する水溶液を、
蒸発缶１内においてフラッシュ蒸発したのち、前記加熱
器２によって加熱する場合、つまり、蒸発缶１内に、フ
ラッシュ蒸発部と加熱器とを設けた場合を示したが、本
発明は、これに限らず、図２に示すように、加熱器２
を、蒸発缶１とは別個に設けた形態にし、前記蒸発缶１
からの出た水溶液に気液混合部２０において熱源として
の蒸気を混合し、結晶析出タンク１５内で結晶を析出
し、次いで、前記蒸発缶１とは別に設け、且つ、大気圧
以下の減圧状態に保持した密閉型のフラッシュ蒸発部２
９内でフラッシュ蒸発したのち、前記加熱器２を経て前
記蒸発缶１に導くようにした構成にしても良いことは言
うまでもなく、また、本発明は、多重効用型蒸発装置に
対しても適用できるのである。In the above embodiment, the heater 2 is provided in the evaporator 1, while the circulating aqueous solution is supplied from the nozzle 18 provided in the evaporator 1 to the heat transfer tube 2c in the heater 2.
By squirting against the circulating aqueous solution,
Although the case where the flash device is heated by the heater 2 after flash evaporation in the evaporation can 1, that is, the flash evaporation unit and the heater are provided in the evaporation can 1, the present invention is not limited to this. First, as shown in FIG.
Is provided separately from the evaporator 1 and the evaporator 1
A vapor as a heat source is mixed with the aqueous solution discharged from the above in the gas-liquid mixing section 20 to precipitate crystals in the crystal precipitation tank 15, and then, is provided separately from the evaporator 1 and a depressurized state below atmospheric pressure. Closed flash evaporation unit 2
It is needless to say that the structure may be such that after flash evaporation in 9 and then to the evaporator 1 via the heater 2, the present invention can also be applied to a multiple-effect evaporator. Of.
【図１】本発明における一つの実施例を示す図である。FIG. 1 is a diagram showing an embodiment of the present invention.
【図２】本発明における他の実施例を示す図である。FIG. 2 is a diagram showing another embodiment of the present invention.
【図３】水に対する硫酸カルシウムの飽和溶解度曲線を
示す図である。FIG. 3 is a diagram showing a saturated solubility curve of calcium sulfate in water.
１ 蒸発缶 ２ 加熱器 ３ 凝縮器 ６ 蒸気ダクト １２ 蒸気エゼクター １４ 第１循環管路 １５ 結晶析出タンク １６ 循環ポンプ １７ 第２循環管路 ２０ 気液混合部 ２１ 補助蒸気エゼクター ２２ 蒸気ダクト ２９ フラッシュ蒸発部 1 Evaporator 2 Heater 3 Condenser 6 Steam Duct 12 Steam Ejector 14 First Circulation Pipeline 15 Crystal Precipitation Tank 16 Circulation Pump 17 Second Circulation Pipeline 20 Gas-Liquid Mixing Section 21 Auxiliary Steam Ejector 22 Steam Duct 29 Flash Evaporating Section
Claims (2)
例する水溶性溶質を含む水溶液を、間接熱交換式の加熱
器にて加熱し、大気圧以下の減圧状態に保持された蒸発
缶内で蒸発するようにした蒸発方法において、前記蒸発
缶で蒸発した後の水溶液に、熱源としての蒸気を混合
し、前記水溶性溶質の結晶を析出してその結晶を分離・
除去し、次いで、大気圧以下の減圧状態でフラッシュ蒸
発したのち、前記加熱器にて加熱する循環を行うことを
特徴とする水に対する飽和溶解度が温度に反比例する水
溶性溶質を含む水溶液の蒸発方法。1. A saturation solubility in water of an aqueous solution containing a water-soluble solutes which is inversely proportional to the rise in temperature, heated at indirect heat exchange type of heater, the evaporator in which is kept below the reduced pressure atmosphere In the evaporation method adapted to evaporate, the aqueous solution after being evaporated in the evaporator is mixed with steam as a heat source, and the crystals of the water-soluble solute are precipitated to separate the crystals.
A method for evaporating an aqueous solution containing a water-soluble solute whose saturated solubility in water is inversely proportional to temperature, which is characterized by performing circulation by heating after removing, and then flash-evaporating under reduced pressure below atmospheric pressure. .
と、多数本の伝熱管を備えた加熱器と、水に対する飽和
溶解度が温度の上昇に反比例する水溶性溶質を含む水溶
液を前記蒸発缶と加熱器との間を循環するようにした循
環経路とから成る蒸発装置において、前記循環経路のう
ち前記蒸発缶から加熱器に至る部分に、前記水溶液に対
して熱源としての蒸気を混合する気液混合部と、大気圧
以下の減圧状態に保持したフラッシュ蒸発部とを、前記
気液混合部を上流側にフラッシュ蒸発部を下流側にして
設け、更に、前記循環経路のうち前記気液混合部とフラ
ッシュ蒸発部との間の部位に、結晶析出タンクを設けた
ことを特徴とする水に対する飽和溶解度が温度に反比例
する水溶性溶質を含む水溶液の蒸発装置。Wherein the evaporator was kept below the reduced pressure atmosphere, a large number of heater equipped with a heat transfer tube, an aqueous solution containing a water-soluble solute saturation solubility in water is inversely proportional to the increase in temperature the evaporator In an evaporator comprising a can and a circulation path that circulates between a heater, a part of the circulation path from the evaporation can to the heater is mixed with steam as a heat source for the aqueous solution. a gas-liquid mixing section, and a flash evaporation unit which is kept below the reduced pressure atmosphere, provided the flash evaporation unit for the gas-liquid mixing section upstream and the downstream side, further, the gas-liquid of the circulation path Mixing section and hula
An apparatus for evaporating an aqueous solution containing a water-soluble solute whose saturation solubility in water is inversely proportional to temperature, characterized in that a crystal precipitation tank is provided in a region between the ash evaporating section .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10150391A JPH0775641B2 (en) | 1991-05-07 | 1991-05-07 | Method and apparatus for evaporating aqueous solution containing water-soluble solute whose saturated solubility in water is inversely proportional to temperature |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10150391A JPH0775641B2 (en) | 1991-05-07 | 1991-05-07 | Method and apparatus for evaporating aqueous solution containing water-soluble solute whose saturated solubility in water is inversely proportional to temperature |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04330901A JPH04330901A (en) | 1992-11-18 |
| JPH0775641B2 true JPH0775641B2 (en) | 1995-08-16 |
Family
ID=14302422
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10150391A Expired - Fee Related JPH0775641B2 (en) | 1991-05-07 | 1991-05-07 | Method and apparatus for evaporating aqueous solution containing water-soluble solute whose saturated solubility in water is inversely proportional to temperature |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0775641B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016180187A (en) * | 2016-07-05 | 2016-10-13 | パンパシフィック・カッパー株式会社 | Concentrating apparatus of sulfuric acid acidic solution, concentrating method of sulfuric acid acidic solution, and recovery method of crude nickel sulfate |
| CN110548310A (en) * | 2019-09-10 | 2019-12-10 | 贵州大龙汇成新材料有限公司 | manganese sulfate solution purification treatment equipment |
-
1991
- 1991-05-07 JP JP10150391A patent/JPH0775641B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04330901A (en) | 1992-11-18 |
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