JPH11123312A - Treatment method for flue gas desulfurization waste water - Google Patents

Treatment method for flue gas desulfurization waste water

Info

Publication number
JPH11123312A
JPH11123312A JP9288174A JP28817497A JPH11123312A JP H11123312 A JPH11123312 A JP H11123312A JP 9288174 A JP9288174 A JP 9288174A JP 28817497 A JP28817497 A JP 28817497A JP H11123312 A JPH11123312 A JP H11123312A
Authority
JP
Japan
Prior art keywords
evaporator
gypsum
flue gas
seed crystal
gas desulfurization
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.)
Granted
Application number
JP9288174A
Other languages
Japanese (ja)
Other versions
JP3534584B2 (en
Inventor
Atsumasa Endou
Hideki Kamiyoshi
Eiji Ochi
Takeo Shinoda
Yoshiyuki Takeuchi
Atsushi Yoshioka
篤 吉岡
秀起 神吉
竹内  善幸
岳男 篠田
英次 越智
篤昌 遠藤
Original Assignee
Mitsubishi Heavy Ind Ltd
三菱重工業株式会社
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Mitsubishi Heavy Ind Ltd, 三菱重工業株式会社 filed Critical Mitsubishi Heavy Ind Ltd
Priority to JP28817497A priority Critical patent/JP3534584B2/en
Publication of JPH11123312A publication Critical patent/JPH11123312A/en
Application granted granted Critical
Publication of JP3534584B2 publication Critical patent/JP3534584B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/02Treatment of water, waste water, or sewage by heating
    • C02F1/04Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34Chemical or biological purification of waste gases
    • B01D53/46Removing components of defined structure
    • B01D53/48Sulfur compounds
    • B01D53/50Sulfur oxides
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D9/00Crystallisation
    • B01D9/0018Evaporation of components of the mixture to be separated
    • B01D9/0031Evaporation of components of the mixture to be separated by heating
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D9/00Crystallisation
    • B01D9/0036Crystallisation on to a bed of product crystals; Seeding
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/58Treatment of water, waste water, or sewage by removing specified dissolved compounds

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method for flue gas desulfurization waste water to prevent a scale from attaching to a liquid contact surface or the like of a vaporization drum and a heater in a flue gas desulfurization plant. SOLUTION: A process (a) in which seed crystals of gypsum are mixed into a desulfurization waste water 1, a process (b) in which the waste water containing the seed crystals is concentrated in a vaporization drum 2 until the waste water has a predetermined concentration ratio to effect a deposit of gypsum in the water 1, and a process (c) in which after the concentrated desulfurization waste water is discharged from the drum 2, the inner surface of the drum 2 is cleaned with a washing water 8a are repeated successively.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION
【0001】[0001]
【発明の属する技術分野】本発明は、石油、石炭等の燃
焼排ガス中の硫黄酸化物を除去する湿式排煙脱硫プラン
トにおける排煙脱硫排水の処理方法に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating flue gas desulfurization wastewater in a wet flue gas desulfurization plant for removing sulfur oxides from flue gas such as petroleum and coal.
【0002】[0002]
【従来の技術】排煙脱硫装置から排出される脱硫排水中
には、各種イオンが多量に含まれている。特に、カルシ
ウムイオンと硫酸イオンは、スケールの生成の原因とな
る成分であり、脱硫排水中に飽和または過飽和の状態で
存在する。脱硫排水を蒸発濃縮すると、スケールが蒸発
缶および加熱器の内面(接液面)や配管等に付着し、熱
効率の低下や配管の閉塞が生じて、運転が困難となる。
そこで、脱硫排水を蒸発濃縮しても、スケール成分が蒸
発缶の内部に付着しない技術が検討されている。その例
として、特開平7−251162号公報に記載の技術を
挙げることができる。
2. Description of the Related Art The desulfurization effluent discharged from a flue gas desulfurization apparatus contains a large amount of various ions. In particular, calcium ions and sulfate ions are components that cause the formation of scale, and are present in the desulfurized effluent in a saturated or supersaturated state. When the desulfurization wastewater is evaporated and concentrated, the scale adheres to the inner surface (liquid contact surface) of the evaporator and the heater, the pipes, and the like, resulting in a decrease in thermal efficiency and blockage of the pipes, making operation difficult.
Therefore, a technology has been studied in which the scale component does not adhere to the inside of the evaporator even when the desulfurization wastewater is evaporated and concentrated. As an example thereof, a technique described in JP-A-7-251162 can be mentioned.
【0003】特開平7−251162号公報には、スケ
ール成分を含む廃液の加熱および濃縮方法であって、蒸
発液の温度を90℃以上とし、無水石膏を種晶として用
い、一定の時間間隔で蒸発ユニットの水洗を行なう方法
が記載されている。しかし、該公報に記載された技術の
ように、蒸発液の温度を90℃以上とし、無水石膏を種
晶として用いると、次のような問題点が生じる。通常、
脱硫装置から排出される石膏は、大部分、二水塩(Ca
SO4 ・2H2O)である。無水石膏(CaSO4 )を
種晶として用いる場合、予め系外に準備した無水石膏を
添加しなければならないため、濃縮液の固形物量が増加
し、最終的には廃棄物量の増加を招く。
Japanese Patent Application Laid-Open No. 7-251162 discloses a method for heating and concentrating a waste liquid containing a scale component, in which the temperature of an evaporating liquid is 90 ° C. or more, and anhydrous gypsum is used as a seed crystal at regular time intervals. A method for washing the evaporation unit with water is described. However, when the temperature of the evaporating liquid is set to 90 ° C. or higher and the anhydrous gypsum is used as a seed crystal as in the technique described in the publication, the following problems occur. Normal,
Most of the gypsum discharged from the desulfurizer is dihydrate (Ca
SO 4 .2H 2 O). When anhydrous gypsum (CaSO 4 ) is used as a seed crystal, since anhydrous gypsum prepared outside the system must be added in advance, the amount of solids in the concentrated solution increases, and eventually the amount of waste increases.
【0004】特に、蒸発ユニットの洗浄時には、無水石
膏を含む濃縮液を、一旦、蒸発ユニットより排出して別
途貯留する。この際、濃縮液の温度が低下(特に45℃
以下)すると、無水石膏は二水石膏に移行する。これを
蒸発ユニットに戻して、再度90〜140℃に加熱して
も、一旦二水石膏になったものは、無水石膏には戻ら
ず、半水塩(CaSO4 ・1/2H2 O)にしかならな
いという性質がある。無水石膏にするためには、さらに
高温に加熱して、脱水しなければならない。したがっ
て、蒸発ユニットの洗浄中に別置した無水石膏を含む濃
縮液を、加熱して90℃以上に保持する操作か、あるい
は、蒸発ユニットの洗浄毎に、ユニット内の種晶を全て
廃棄して、系外から無水石膏を新たに添加する操作が必
要になる。このため、加熱量の増加、または廃棄物量の
増加を避けることはできない。
In particular, when the evaporating unit is washed, the concentrated liquid containing anhydrous gypsum is once discharged from the evaporating unit and stored separately. At this time, the temperature of the concentrate decreases (particularly 45 ° C.).
Then, anhydrous gypsum is converted to gypsum. Even if this is returned to the evaporating unit and heated again to 90 to 140 ° C., the gypsum once converted to gypsum does not return to anhydrous gypsum but to hemihydrate (CaSO 4 .1 / 2H 2 O). There is a property that must be. In order to form anhydrous gypsum, it must be further heated to a high temperature and dehydrated. Therefore, the concentrated liquid containing anhydrous gypsum separately placed during the washing of the evaporation unit is heated and maintained at 90 ° C. or higher, or every time the washing of the evaporation unit is performed, all seed crystals in the unit are discarded. In addition, it is necessary to newly add anhydrous gypsum from outside the system. Therefore, an increase in the amount of heating or an amount of waste cannot be avoided.
【0005】[0005]
【発明が解決しようとする課題】本発明は、このような
問題点を解決すべくなされたものであり、スケールの生
成を防止しつつ脱硫排水を蒸発濃縮するための排煙脱硫
排水の処理方法を提供することを目的とする。
SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and a method for treating flue gas desulfurization wastewater for evaporating and condensing desulfurization wastewater while preventing the formation of scale. The purpose is to provide.
【0006】[0006]
【課題を解決するための手段】本発明の排煙脱硫排水の
処理方法は、脱硫排水に石膏の種晶を含有させる工程
(a)と、種晶を含有させた該脱硫排水を、蒸発缶内に
おいて所定の濃縮比になるまで濃縮させて、該脱硫排水
中の石膏を析出させる工程(b)と、濃縮された該脱硫
排水を、該蒸発缶から排出させたのち、該蒸発缶の内面
を洗浄水によって洗浄する工程(c)とを、順次繰り返
すことを特徴とする(請求項1)。
According to the method for treating flue gas desulfurization wastewater of the present invention, a step (a) of adding gypsum seed crystals to the desulfurization wastewater is performed. (B) precipitating the gypsum in the desulfurization effluent by concentrating to a predetermined concentration ratio in the inside, and discharging the concentrated desulfurization effluent from the evaporator, And step (c) of washing with a washing water are sequentially repeated (claim 1).
【0007】上記工程(a)は、蒸発缶に導入される前
の脱硫排水に種晶を添加する操作と、上記(b)工程前
に予め、種晶を含有する濃縮液を蒸発缶に供給する操作
と、上記(b)工程中に、蒸発缶内で晶析する石膏自体
を種晶(自己種晶)とする操作とから選ばれる一つ以上
の操作からなることができる(請求項2)。
In the step (a), the seed crystal is added to the desulfurization wastewater before being introduced into the evaporator, and before the step (b), the concentrated liquid containing the seed crystal is supplied to the evaporator in advance. And the operation of setting the gypsum itself crystallized in the evaporator during the step (b) as a seed crystal (self-seed crystal). ).
【0008】上記種晶を含有する濃縮液として、上記蒸
発缶から排出される脱硫排水の濃縮液を用いることがで
きる(請求項3)。上記種晶として、二水塩の形態の石
膏を用い、かつ、上記蒸発缶内での脱硫排水の濃縮を、
45〜90℃の温度条件下で行うことができる(請求項
4)。上記蒸発缶内での脱硫排水の濃縮比を、石膏の晶
析速度と種晶濃度の比が特定範囲内となるように定める
ことができる(請求項5)。上記(c)工程の洗浄水と
して、上記蒸発缶から排出される水蒸気を凝縮して得ら
れる凝結水と、該凝結水を得るのに使用された後の冷却
水と、該凝結水と該冷却水の混合液とから選ばれる一つ
以上を用いることができる(請求項6)。
[0008] As the concentrated liquid containing the seed crystal, a concentrated liquid of desulfurization effluent discharged from the evaporator can be used. As the seed crystal, gypsum in the form of dihydrate is used, and the concentration of the desulfurization wastewater in the evaporator is
It can be carried out under a temperature condition of 45 to 90 ° C (claim 4). The concentration ratio of the desulfurization effluent in the evaporator can be determined so that the ratio of the crystallization speed of gypsum to the seed crystal concentration falls within a specific range (claim 5). Condensed water obtained by condensing steam discharged from the evaporator as the washing water in the step (c), cooling water used to obtain the condensed water, the condensed water and the cooling One or more selected from a mixture of water can be used (claim 6).
【0009】[0009]
【発明の実施の形態】排煙脱硫排水の処理方法の実施形
態の一例を図1に示す。図1において、脱硫排水1は、
蒸発缶2内に供給され、所定の温度条件下で、所定の濃
度になるまで、加熱器3によって加熱され、蒸発缶2で
蒸発濃縮される。加熱器3には、加熱用水蒸気4が導入
され、復水5が排出される。蒸発缶2から排出される水
蒸気6は、冷却装置7によって冷却されて凝結水8とな
る。凝結水8は、一旦貯留されたのち(図示せず)、一
部量は、洗浄水8aとして蒸発缶2に供給され、大部分
量は、補給水8bとして脱硫装置へ送られる。
FIG. 1 shows an example of an embodiment of a method for treating flue gas desulfurization wastewater. In FIG. 1, the desulfurization wastewater 1 is
It is supplied into the evaporator 2, is heated by the heater 3 under a predetermined temperature condition until a predetermined concentration is obtained, and is concentrated by evaporation in the evaporator 2. Heating steam 4 is introduced into the heater 3, and condensed water 5 is discharged. The steam 6 discharged from the evaporator 2 is cooled by the cooling device 7 to form condensed water 8. After the condensed water 8 is once stored (not shown), a part of the condensed water 8 is supplied to the evaporator 2 as washing water 8a, and a large part of the condensed water is sent to a desulfurization device as makeup water 8b.
【0010】蒸発缶2内で濃縮された脱硫排水の濃縮液
9の大部分は、ポンプ10によって加熱器3を経て蒸発
缶2に返送・循環され、その一部の濃縮液12は、濃縮
液槽11に供給される。濃縮液槽11内の濃縮液12a
は、ポンプ13によって、種晶として蒸発缶2に供給さ
れる。蒸発缶2に供給される脱硫排水1には、必要に応
じて種晶を添加することができる。濃縮液槽11内の大
部分の濃縮液12bは、固化装置14に送られ、石炭灰
およびポルトランドセメント(図示せず)等の固化促進
剤と混合し、固化されて、固化物15となり廃棄され
る。このように固化装置14を用いることによって、汚
濁物質を含む排水の排出制限に対応することができる。
蒸発缶2および加熱器3の接液面の洗浄に用いられる洗
浄水8aは、蒸発缶2等の洗浄後、洗浄排水16として
脱硫装置へ送られ、脱硫装置の補給水として使用され
る。
Most of the concentrated liquid 9 of the desulfurization effluent concentrated in the evaporator 2 is returned and circulated to the evaporator 2 via the heater 3 by the pump 10, and a part of the concentrated liquid 12 is It is supplied to the tank 11. The concentrate 12a in the concentrate tank 11
Is supplied to the evaporator 2 as seed crystals by the pump 13. Seed crystals can be added to the desulfurization wastewater 1 supplied to the evaporator 2 as needed. Most of the concentrated liquid 12b in the concentrated liquid tank 11 is sent to a solidifying device 14, where it is mixed with a solidification accelerator such as coal ash and Portland cement (not shown), solidified, solidified into a solid 15 and discarded. You. By using the solidifying device 14 in this manner, it is possible to cope with the discharge restriction of the wastewater containing the pollutant.
The washing water 8a used for washing the liquid contact surfaces of the evaporator 2 and the heater 3 is sent to the desulfurizer as washing waste water 16 after washing the evaporator 2 and the like, and is used as makeup water for the desulfurizer.
【0011】なお、冷却装置7には通常、循環冷却水が
供給される(図示せず)。この循環冷却水中の塩濃度を
一定に保つために、一部ブローされる。このブロー水の
一部量を前記の凝結水8とともに洗浄水8aとして用い
ることができ、その大部分量は、補給水8bとともに脱
硫装置への補給水として利用できる。以下、本発明の方
法を工程順に説明する。
The cooling device 7 is usually supplied with circulating cooling water (not shown). Part of the circulating cooling water is blown to keep the salt concentration constant. A part of this blow water can be used together with the condensed water 8 as the washing water 8a, and most of the blow water can be used together with the makeup water 8b as makeup water for the desulfurization device. Hereinafter, the method of the present invention will be described in the order of steps.
【0012】第1工程 排煙脱硫排水に石膏の種晶(結晶種)を添加する工程で
ある。排煙脱硫排水は、石炭、重油等の燃焼排ガス中の
硫黄酸化物を除去する湿式排煙脱硫装置からの排水であ
る。石膏は、溶解度が温度の上昇と共に減少する物質で
あり、そのため、加熱面にスケールとなって付着しやす
い。スケールとして付着する石膏の結晶は、二水塩、半
水塩、無水塩の三形態をとり、高温になるほど結晶水の
少ない形態となる。半水塩は、脱水および吸水の転移速
度が比較的大きいが、無水塩の晶析速度は、45〜14
0℃では比較的小さい。そのため、二水塩を湿式加熱
(45〜140℃)すると半水石膏が生成し、無水塩を
得るためにはさらに高温に加熱して脱水しなければなら
ないという性質がある。
The first step is a step of adding gypsum seed crystals (crystal seeds) to flue gas desulfurization wastewater. Flue gas desulfurization wastewater is wastewater from a wet flue gas desulfurization device that removes sulfur oxides in combustion exhaust gas such as coal and heavy oil. Gypsum is a substance whose solubility decreases with increasing temperature, and therefore tends to adhere to the heated surface as a scale. The gypsum crystals that adhere as scales take three forms: dihydrate, hemihydrate, and anhydrous salt. The higher the temperature, the less the amount of water of crystallization. Hemihydrate has a relatively high rate of dehydration and water absorption, while the rate of crystallization of the anhydrous salt is 45-14.
It is relatively small at 0 ° C. Therefore, when the dihydrate is wet-heated (45 to 140 ° C.), hemihydrate gypsum is generated, and in order to obtain an anhydrous salt, it has to be heated to a higher temperature to be dehydrated.
【0013】種晶としては、脱硫排水中の石膏の結晶と
同じものを用いるのが好ましい。例えば、二水塩が析出
する濃縮条件下には、二水塩を種晶として用いるのが好
ましく、逆に、無水塩が析出する濃縮条件下に、二水塩
を種晶として用いると、石膏の析出がほとんどなく、種
晶の添加の効果が小さくなる。脱硫排水中に含まれる石
膏の大部分は、二水塩(CaSO4 ・2H2 O)であ
る。種晶として二水塩の石膏を用いると、無水塩の石膏
(CaSO4 )の場合のように、蒸発缶の洗浄時の種晶
の加温操作や、系外から新たに無水石膏を添加する操作
が不要であるという利点がある。このときの蒸発缶内の
温度は、45〜90℃、好ましくは55〜70℃とす
る。45℃未満であると、蒸発缶内は高い真空度としな
ければならないので、高性能の真空ポンプを要し、経済
的でないという欠点があり、90℃を超えると、スケー
ル付着防止の効果が低下するとともに、蒸発濃縮操作に
要する加熱用熱量が多くなるという欠点がある。
It is preferable to use the same seed crystal as the gypsum crystal in the desulfurization effluent. For example, it is preferable to use dihydrate as a seed crystal under the concentration conditions under which dihydrate precipitates, and conversely, if the dihydrate is used as a seed crystal under the concentration conditions under which anhydrous salts precipitate, gypsum Is hardly precipitated, and the effect of adding a seed crystal is reduced. Most of the gypsum contained in the desulfurization effluent is dihydrate (CaSO 4 · 2H 2 O) . When gypsum of dihydrate is used as a seed crystal, as in the case of gypsum of anhydrous salt (CaSO 4 ), a heating operation of the seed crystal at the time of washing the evaporator or a new anhydrous gypsum is added from outside the system. There is an advantage that no operation is required. The temperature in the evaporator at this time is 45 to 90 ° C, preferably 55 to 70 ° C. If the temperature is lower than 45 ° C., the inside of the evaporator must have a high degree of vacuum. Therefore, a high-performance vacuum pump is required, which is not economical. If the temperature exceeds 90 ° C., the effect of preventing scale adhesion is reduced. In addition, there is a disadvantage that the amount of heat for heating required for the evaporative concentration operation is increased.
【0014】蒸発缶2に供給される脱硫排水1に種晶を
予め添加する場合、種晶の添加量は、蒸発缶内に保有さ
れる脱硫排水1リットル当たり、二水石膏(CaSO4
・2H2 O)として、1〜20g、好ましくは2〜10
gである。種晶の添加量が1g未満であると、後記第2
工程における蒸発缶内の脱硫排水の濃縮の際に、石膏の
析出量に対する種晶量が少ないため、石膏スケールの付
着量が増加するという欠点があり、20gを超えると、
添加効果は向上せず、廃棄物量が増加するという欠点が
ある。
When seed crystals are added in advance to the desulfurization wastewater 1 supplied to the evaporator 2, the amount of the seed crystals added per liter of the desulfurization wastewater held in the evaporator is gypsum dihydrate (CaSO 4
2H 2 O), 1 to 20 g, preferably 2 to 10 g
g. If the amount of the seed crystal added is less than 1 g, the second
At the time of concentration of the desulfurization effluent in the evaporator in the process, since the amount of seed crystals with respect to the amount of precipitated gypsum is small, there is a disadvantage that the amount of gypsum scale adhered increases.
There is a disadvantage that the effect of addition is not improved and the amount of waste increases.
【0015】なお、この方法は、運転開始当初、蒸発缶
内に保有する脱硫排水量に対してのみ行なう。後記第2
工程において、蒸発缶内で所定濃縮比で定常的に濃縮し
ている場合は、脱硫排水に種晶を予め添加する必要はな
い。また、ここで用いる種晶は、脱硫装置で生成した石
膏(二水塩)でよいから、脱硫設備内の石膏分離工程で
石膏回収率を調整することで、脱硫排水の石膏濃度を調
整できるため、新たに種晶供給装置等の付属設備を設け
る必要はない。
This method is performed only for the desulfurization wastewater retained in the evaporator at the beginning of the operation. Postscript 2
In the process, when the concentration is constantly performed at a predetermined concentration ratio in the evaporator, it is not necessary to add a seed crystal to the desulfurization wastewater in advance. In addition, since the seed crystal used here may be gypsum (dihydrate) generated in a desulfurization device, the gypsum concentration of the desulfurization effluent can be adjusted by adjusting the gypsum recovery rate in the gypsum separation step in the desulfurization facility. It is not necessary to provide additional equipment such as a seed crystal supply device.
【0016】蒸発缶2に脱硫排水1を供給する前に、予
め種晶を含有する濃縮液を蒸発缶2に供給する場合は、
後記第3工程で蒸発缶から排出した脱硫排水の濃縮液1
2を用いることによって、前記の蒸発缶内に保有する濃
縮液の種晶(石膏二水塩)濃度を容易に確保することが
できる。これは、前記のとおり、脱硫排水の濃縮液12
aの液温が低温(45℃以下)になっても、二水塩の石
膏は安定した形態を維持でき、種晶として利用できるか
らである。
When a concentrated liquid containing seed crystals is supplied to the evaporator 2 before the desulfurization wastewater 1 is supplied to the evaporator 2,
Concentrated liquid 1 of desulfurization effluent discharged from the evaporator in the third step described later
By using 2, the concentration of the seed crystal (gypsum dihydrate) of the concentrated liquid held in the evaporator can be easily ensured. This is, as described above, the concentrated liquid 12 of the desulfurization wastewater.
This is because even if the liquid temperature of a becomes low (45 ° C. or less), the gypsum of the dihydrate can maintain a stable form and can be used as a seed crystal.
【0017】第2工程 脱硫排水を、蒸発缶内において、所定の濃縮比になるま
で濃縮させて、脱硫排水中の石膏を析出させる工程であ
る。ここで、濃縮比とは、蒸発缶に供給する脱硫排水量
と蒸発缶から排出される濃縮スラリー量の重量比を意味
する。蒸発缶内での脱硫排水の濃縮比は、石膏の晶析速
度(γ)と種晶濃度(Cs)の比(γ/Cs)が特定範
囲内となるように定めるのが好ましい。具体的には、晶
析速度(モル/L/hour)と種晶濃度(g/m3
の比(γ/Cs)が2000以上、より好ましくは30
00以上となるように濃縮比を設定するのが好ましい。
比が2000未満であると、蒸発缶の内面にスケールが
付着するおそれがある。比(γ/Cs)の上限は、通
常、4000程度である。
The second step is a step of concentrating the desulfurized wastewater in the evaporator to a predetermined concentration ratio to precipitate gypsum in the desulfurized wastewater. Here, the concentration ratio means the weight ratio of the amount of desulfurization wastewater supplied to the evaporator to the amount of concentrated slurry discharged from the evaporator. The concentration ratio of the desulfurization effluent in the evaporator is preferably determined so that the ratio (γ / Cs) between the gypsum crystallization speed (γ) and the seed crystal concentration (Cs) falls within a specific range. Specifically, crystallization rate (mol / L / hour) and seed crystal concentration (g / m 3 )
Of (γ / Cs) is 2,000 or more, more preferably 30
It is preferable to set the concentration ratio so as to be 00 or more.
If the ratio is less than 2000, scale may adhere to the inner surface of the evaporator. The upper limit of the ratio (γ / Cs) is usually about 4000.
【0018】蒸発缶2で脱硫排水1を濃縮すると、種晶
表面に石膏(二水塩)が析出して結晶が成長し、石膏濃
度が増加する。やがて所定の濃縮比を一定に維持する
と、供給される脱硫排水1からの石膏析出量と蒸発缶2
からの濃縮液12中の石膏の流出量が釣り合って、蒸発
缶2内の石膏濃度が一定となる。すなわち、蒸発缶2内
の晶析石膏(二水塩)そのものが種晶(以下、これを
「自己種晶」という。)となる。蒸発缶2内の濃縮液9
に含まれる自己種晶は、ポンプ10によって加熱器3を
経て蒸発缶2へと循環される際、蒸発缶、加熱器、付属
機器および配管の接液面で常に種晶として作用するた
め、接液面での石膏スケールの付着が防止される。
When the desulfurization effluent 1 is concentrated in the evaporator 2, gypsum (dihydrate) precipitates on the surface of the seed crystal, crystals grow, and the gypsum concentration increases. Eventually, when the predetermined concentration ratio is maintained constant, the amount of gypsum deposited from the supplied desulfurization wastewater 1 and the evaporator 2
The amount of gypsum in the concentrated liquid 12 flowing out of the evaporator 2 is balanced, and the gypsum concentration in the evaporator 2 becomes constant. That is, the crystallized gypsum (dihydrate) itself in the evaporator 2 becomes a seed crystal (hereinafter, referred to as “self-seed crystal”). Concentrate 9 in evaporator 2
The self-seed crystal contained in the evaporator, which is circulated to the evaporator 2 via the heater 3 by the pump 10, always acts as a seed crystal on the liquid contact surfaces of the evaporator, the heater, ancillary equipment, and piping. The adhesion of gypsum scale on the liquid surface is prevented.
【0019】また、石膏結晶の成長により、蒸発缶内の
石膏結晶が粗大化する。通常、結晶が粗大化した場合、
結晶表面積が低下するため、種晶としての効果が低下す
る。しかし、本発明では、蒸発缶内の濃縮液が、ポンプ
10により加熱器3を経て蒸発器2に循環される際に、
機械的衝撃によって石膏結晶のほとんどが細分化され、
蒸発缶内での種晶として利用できるため、特に自己種晶
の破砕工程(装置)を設けなくてよい。
The gypsum crystals in the evaporator become coarse due to the growth of the gypsum crystals. Usually, when the crystal becomes coarse,
Since the crystal surface area is reduced, the effect as a seed crystal is reduced. However, in the present invention, when the concentrated liquid in the evaporator is circulated to the evaporator 2 via the heater 3 by the pump 10,
Most of the gypsum crystals are subdivided by mechanical impact,
Since it can be used as a seed crystal in the evaporator, it is not necessary to particularly provide a crushing step (apparatus) for self-seed crystals.
【0020】第3工程 濃縮された脱硫排水を、蒸発缶から排出させたのち、蒸
発缶、加熱器、ポンプおよび配管の接液面を洗浄水によ
って洗浄する工程である。まず、蒸発缶2、加熱器3、
ポンプ10および配管から排出した濃縮液12は、濃縮
液槽11に貯留する。ついで、洗浄水8aを蒸発缶2に
導入し、ポンプ10によって加熱器3を経て蒸発缶2に
所定時間返送・循環すると、接液面に発生した石膏スケ
ールは、洗浄水8aによって溶解される。
The third step is a step of discharging the concentrated desulfurized wastewater from the evaporator, and then washing the liquid contact surfaces of the evaporator, the heater, the pump and the piping with washing water. First, evaporator 2, heater 3,
The concentrate 12 discharged from the pump 10 and the piping is stored in a concentrate tank 11. Then, the washing water 8a is introduced into the evaporator 2 and is returned and circulated to the evaporator 2 via the heater 3 by the pump 10 for a predetermined time, whereby the gypsum scale generated on the liquid contact surface is dissolved by the washing water 8a.
【0021】この濃縮液接液面の洗浄頻度は、脱硫装置
の運転負荷により変わるが、12〜120時間毎に1
回、好ましくは12〜48時間に1回である。1回当た
りの洗浄時間は30分間以上、好ましくは1時間以上で
ある。所定時間の洗浄後、蒸発缶2からの洗浄排水16
は、脱硫装置に送り、補給水として利用することができ
る。
The frequency of cleaning the liquid contact surface of the concentrated liquid varies depending on the operation load of the desulfurization apparatus.
Times, preferably once every 12 to 48 hours. The washing time per time is 30 minutes or more, preferably 1 hour or more. After washing for a predetermined time, the washing wastewater 16 from the evaporator 2 is removed.
Can be sent to a desulfurization unit and used as makeup water.
【0022】なお、洗浄用水としては、凝結水8aのほ
かに、冷却装置7に供給される循環冷却水のブロー水の
一部量、または凝結水8aと該ブロー水の混合水を用い
ることができる。これらの洗浄用水は比較的清澄で、石
膏スケールを溶解させることができるだけでなく、工業
用水量の節減に役立つ。洗浄排水16を蒸発缶2から排
出した後は、濃縮液12をポンプ13によって蒸発缶2
に導入し、前記の第1工程に移行して、脱硫排水1の濃
縮を再開する。
As the washing water, in addition to the condensed water 8a, a part of the blow water of the circulating cooling water supplied to the cooling device 7, or a mixed water of the condensed water 8a and the blow water may be used. it can. These wash waters are relatively clear and not only can dissolve gypsum scale, but also help to reduce industrial water usage. After the washing wastewater 16 is discharged from the evaporator 2, the concentrated liquid 12 is pumped by the pump 13.
Then, the process proceeds to the first step, and the concentration of the desulfurization wastewater 1 is restarted.
【0023】[0023]
【発明の効果】本発明の方法によれば、蒸発缶、加熱
器、付属機器および配管等の脱硫排水の接液面へのスケ
ールの付着を、種晶の添加によって防止しつつ、加熱蒸
発による脱硫排水の濃縮を行なうことができる。
According to the method of the present invention, the adhesion of scale to the liquid contact surface of desulfurization effluent such as an evaporator, a heater, an accessory and piping is prevented by the addition of a seed crystal, while the evaporation by heating is carried out. The desulfurization wastewater can be concentrated.
【図面の簡単な説明】[Brief description of the drawings]
【図1】本発明の方法の実施形態の一例を示す概略図で
ある。
FIG. 1 is a schematic diagram showing an example of an embodiment of the method of the present invention.
【符号の説明】[Explanation of symbols]
1 脱硫排水 2 蒸発缶 3 加熱器 4 加熱用水蒸気 5 復水 6 水蒸気 7 冷却装置 8 凝結水 8a 洗浄水 8b 補給水 9 濃縮液 10 循環ポンプ 11 濃縮液槽 12、12a、12b 濃縮液 13 濃縮液ポンプ 14 固化装置 15 固化物 16 洗浄排水 DESCRIPTION OF SYMBOLS 1 Desulfurization wastewater 2 Evaporator 3 Heater 4 Heating steam 5 Condensed water 6 Steam 7 Cooling device 8 Condensed water 8a Washing water 8b Makeup water 9 Concentrate 10 Circulation pump 11 Concentrate tank 12, 12a, 12b Concentrate 13 Concentrate Pump 14 Solidifying device 15 Solidified material 16 Cleaning drainage
───────────────────────────────────────────────────── フロントページの続き (72)発明者 竹内 善幸 広島県広島市西区観音新町四丁目6番22号 三菱重工業株式会社広島研究所内 (72)発明者 神吉 秀起 兵庫県神戸市兵庫区小松通五丁目1番16号 株式会社神菱ハイテック内 (72)発明者 遠藤 篤昌 兵庫県神戸市兵庫区小松通五丁目1番16号 株式会社神菱ハイテック内 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshiyuki Takeuchi, Inventor Hiroshima Research Institute, Hiroshima City, Hiroshima Pref. 5-1-1-16, Shinryo High-Tech Co., Ltd.

Claims (6)

    【特許請求の範囲】[Claims]
  1. 【請求項1】 脱硫排水に石膏の種晶を含有させる工程
    (a)と、種晶を含有させた該脱硫排水を、蒸発缶内に
    おいて所定の濃縮比になるまで濃縮させて、該脱硫排水
    中の石膏を析出させる工程(b)と、濃縮された該脱硫
    排水を、該蒸発缶から排出させたのち、該蒸発缶の内面
    を洗浄水によって洗浄する工程(c)とを、順次繰り返
    すことを特徴とする排煙脱硫装置から排出される排煙脱
    硫排水の処理方法。
    1. A step (a) of including gypsum seed crystals in desulfurized wastewater, and the desulfurized wastewater containing seed crystals is concentrated in an evaporator until a predetermined concentration ratio is obtained. Step (b) of depositing gypsum therein and step (c) of discharging the concentrated desulfurized wastewater from the evaporator and then washing the inner surface of the evaporator with washing water are sequentially repeated. A method for treating flue gas desulfurization wastewater discharged from a flue gas desulfurization device.
  2. 【請求項2】 上記工程(a)が、蒸発缶に導入される
    前の脱硫排水に種晶を添加する操作と、上記(b)工程
    前に予め、種晶を含有する濃縮液を蒸発缶に供給する操
    作と、上記(b)工程中に、蒸発缶内で晶析する石膏自
    体を種晶とする操作とから選ばれる一つ以上の操作から
    なる請求項1に記載の排煙脱硫排水の処理方法。
    2. The method according to claim 1, wherein the step (a) comprises adding an seed crystal to the desulfurization effluent before being introduced into the evaporator, and the step (b) further comprising: 2. The flue gas desulfurization effluent according to claim 1, comprising one or more operations selected from an operation of supplying gypsum itself and a process of using gypsum itself crystallized in the evaporator as a seed crystal during the step (b). 3. Processing method.
  3. 【請求項3】 上記種晶を含有する濃縮液が、上記蒸発
    缶から排出される脱硫排水の濃縮液である請求項1また
    は2に記載の排煙脱硫排水の処理方法。
    3. The method for treating flue gas desulfurization wastewater according to claim 1, wherein the concentrate containing the seed crystal is a concentrate of desulfurization wastewater discharged from the evaporator.
  4. 【請求項4】 上記種晶として、二水塩の形態の石膏を
    用い、かつ、上記蒸発缶内での脱硫排水の濃縮が、45
    〜90℃の温度条件下で行われる請求項1〜3のいずれ
    かに記載の排煙脱硫排水の処理方法。
    4. Gypsum in the form of dihydrate is used as the seed crystal, and the concentration of desulfurization wastewater in the evaporator is 45%.
    The method for treating flue gas desulfurization effluent according to any one of claims 1 to 3, which is performed under a temperature condition of ~ 90 ° C.
  5. 【請求項5】 上記蒸発缶内での脱硫排水の濃縮比が、
    石膏の晶析速度と種晶濃度の比が特定範囲内となるよう
    に定められる請求項1〜4のいずれかに記載の排煙脱硫
    排水の処理方法。
    5. The concentration ratio of desulfurization effluent in the evaporator is:
    The method for treating flue gas desulfurization effluent according to any one of claims 1 to 4, wherein the ratio between the gypsum crystallization rate and the seed crystal concentration is determined to be within a specific range.
  6. 【請求項6】 上記(c)工程の洗浄水が、上記蒸発缶
    から排出される水蒸気を凝縮して得られる凝結水と、該
    凝結水を得るのに使用された後の冷却水と、該凝結水と
    該冷却水の混合液とから選ばれる一つ以上からなる請求
    項1に記載の排煙脱硫排水の処理方法。
    6. The condensed water obtained by condensing steam discharged from the evaporator in the washing water in the step (c), cooling water used for obtaining the condensed water, 2. The method for treating flue gas desulfurization wastewater according to claim 1, comprising at least one selected from condensed water and a mixture of the cooling water.
JP28817497A 1997-10-21 1997-10-21 Treatment of flue gas desulfurization wastewater Expired - Lifetime JP3534584B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP28817497A JP3534584B2 (en) 1997-10-21 1997-10-21 Treatment of flue gas desulfurization wastewater

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP28817497A JP3534584B2 (en) 1997-10-21 1997-10-21 Treatment of flue gas desulfurization wastewater
TW087114753A TW436467B (en) 1997-10-21 1998-09-05 Process for the treatment of flue gas desulfurization waste water
KR1019980040481A KR100312938B1 (en) 1997-10-21 1998-09-29 Processes for the treatment of flue gas desulfurization waste water
IDP981375A ID21178A (en) 1997-10-21 1998-10-19 PROCESS FOR TREATING WASTE DESULFURIZATION OF WASTE GAS
CNB981213839A CN1162334C (en) 1997-10-21 1998-10-20 Process for treatment of flue gas desulfurization waste water
HK99104893A HK1019730A1 (en) 1997-10-21 1999-10-29 Process for the treatment of flue gas desulfurization waste water.

Publications (2)

Publication Number Publication Date
JPH11123312A true JPH11123312A (en) 1999-05-11
JP3534584B2 JP3534584B2 (en) 2004-06-07

Family

ID=17726779

Family Applications (1)

Application Number Title Priority Date Filing Date
JP28817497A Expired - Lifetime JP3534584B2 (en) 1997-10-21 1997-10-21 Treatment of flue gas desulfurization wastewater

Country Status (6)

Country Link
JP (1) JP3534584B2 (en)
KR (1) KR100312938B1 (en)
CN (1) CN1162334C (en)
HK (1) HK1019730A1 (en)
ID (1) ID21178A (en)
TW (1) TW436467B (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005152745A (en) * 2003-11-25 2005-06-16 Babcock Hitachi Kk Wet flue gas desulfurization method and wet flue gas desulfurizer
JP2012040469A (en) * 2010-08-16 2012-03-01 Japan Organo Co Ltd Washing method of evaporation concentration apparatus, washing apparatus of evaporation concentration apparatus, wastewater treatment method and wastewater treatment apparatus
WO2014174647A1 (en) * 2013-04-25 2014-10-30 三菱重工業株式会社 Water treatment method and water treatment system
CN105502540A (en) * 2016-01-27 2016-04-20 成都锐思环保技术股份有限公司 Anti-scaling and anti-corrosion desulfurization waste water multi-effect evaporation, concentration and crystallization method
CN105502792A (en) * 2016-01-27 2016-04-20 成都锐思环保技术股份有限公司 Zero-discharge treatment method of desulfurization waste water
CN105523677A (en) * 2016-01-27 2016-04-27 成都锐思环保技术股份有限公司 Treatment system capable of realizing zero discharge of desulfurization wastewater
JPWO2014041986A1 (en) * 2012-09-12 2016-08-18 三菱重工業株式会社 Desulfurization apparatus and method of using condensed water generated there

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101417827B (en) * 2007-10-26 2011-09-21 余乐 Technique method for processing desulphurization waste water
CN101417826B (en) * 2007-10-26 2011-12-21 余乐 Method and system for processing desulphurization waste water
CN101417828B (en) * 2007-10-26 2011-09-21 余乐 Method and system for processing desulphurization waste water
CN101613161B (en) * 2008-06-26 2011-04-20 上海梅山钢铁股份有限公司 Method for treating and using sintering flue gas desulphurization wastewater and special device thereof
US8388917B2 (en) * 2010-02-25 2013-03-05 Mitsubishi Heavy Industries, Ltd. Air pollution control system and air pollution control method
CN106242144B (en) * 2016-08-19 2019-12-31 北京国电富通科技发展有限责任公司 Method and system for realizing reflux self-balancing of evaporative crystallization mother liquor based on gypsum seed crystal process

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR960010361B1 (en) * 1991-05-29 1996-07-31 가부시기가이샤 사사쿠라 기카이 세이사쿠쇼 Evaporating method and apparatus of aqueous solution
JPH07251162A (en) * 1994-01-31 1995-10-03 Kikai Kagaku Kenkyusho:Kk Treatment of waste liquid

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005152745A (en) * 2003-11-25 2005-06-16 Babcock Hitachi Kk Wet flue gas desulfurization method and wet flue gas desulfurizer
JP4587197B2 (en) * 2003-11-25 2010-11-24 バブコック日立株式会社 Wet flue gas desulfurization method and apparatus
JP2012040469A (en) * 2010-08-16 2012-03-01 Japan Organo Co Ltd Washing method of evaporation concentration apparatus, washing apparatus of evaporation concentration apparatus, wastewater treatment method and wastewater treatment apparatus
JPWO2014041986A1 (en) * 2012-09-12 2016-08-18 三菱重工業株式会社 Desulfurization apparatus and method of using condensed water generated there
WO2014174647A1 (en) * 2013-04-25 2014-10-30 三菱重工業株式会社 Water treatment method and water treatment system
JP5968524B2 (en) * 2013-04-25 2016-08-10 三菱重工業株式会社 Water treatment method and water treatment system
CN105502540A (en) * 2016-01-27 2016-04-20 成都锐思环保技术股份有限公司 Anti-scaling and anti-corrosion desulfurization waste water multi-effect evaporation, concentration and crystallization method
CN105502792A (en) * 2016-01-27 2016-04-20 成都锐思环保技术股份有限公司 Zero-discharge treatment method of desulfurization waste water
CN105523677A (en) * 2016-01-27 2016-04-27 成都锐思环保技术股份有限公司 Treatment system capable of realizing zero discharge of desulfurization wastewater

Also Published As

Publication number Publication date
HK1019730A1 (en) 2000-02-25
ID21178A (en) 1999-04-29
KR19990036699A (en) 1999-05-25
TW436467B (en) 2001-05-28
KR100312938B1 (en) 2002-07-18
CN1162334C (en) 2004-08-18
CN1216290A (en) 1999-05-12
JP3534584B2 (en) 2004-06-07

Similar Documents

Publication Publication Date Title
JPH11123312A (en) Treatment method for flue gas desulfurization waste water
JP4519485B2 (en) Phosphorus recovery method and apparatus
CN107758962A (en) A kind of system of the preparing magnesium sulfate from desulfurization wastewater
JPH11513357A (en) Salt production method and equipment
JP2004261640A (en) Dephosphorization method for waste water
CN102448885A (en) Device and method for separating and extracting sodium and potassium
KR101860295B1 (en) Treatment Apparatus of FGD Wastewater by using Vacuum Evaporation and Method Thereof
JP4097910B2 (en) Method and apparatus for removing phosphorus
JP2008073662A (en) Recycling method of hydroxyapatite crystal
JP2005193189A (en) Anaerobic treatment method and anaerobic treatment apparatus
JP2004067922A (en) Process for treating de-ammoniacal liquor
JP2011083657A (en) Treatment apparatus of phosphorus-containing wastewater
CN104276707A (en) Evaporative treatment method for aqueous solution
JPH07251162A (en) Treatment of waste liquid
CN207792939U (en) A kind of system of the preparing magnesium sulfate from desulfurization wastewater
CN104402124A (en) Calcium sulfate seed crystal crystallization device and calcium sulfate seed crystal crystallization method
EP0074438A1 (en) Apparatus and process for simultaneously dissipating industrial waste heat and removing dissolved solids from water
JP4052432B2 (en) Method and apparatus for removing ions in liquid by crystallization method
JPH11104450A (en) Treatment of desulfurization waste water
JP2018162201A (en) Ammonium sulfate manufacturing method and ammonium sulfate manufacturing facility
CN205676308U (en) Desulfurizing waste water processing device
JPH0671297A (en) Organic sludge treating method
GB2304296A (en) Distillation process
JPH11226302A (en) Wastewater treatment method
JPS58205501A (en) Depositing method of electrolyte salts

Legal Events

Date Code Title Description
A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20031128

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20040119

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20040220

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20040309

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20080319

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20090319

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100319

Year of fee payment: 6

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110319

Year of fee payment: 7

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110319

Year of fee payment: 7

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120319

Year of fee payment: 8

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130319

Year of fee payment: 9

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20140319

Year of fee payment: 10

EXPY Cancellation because of completion of term