JPH02152518A - Treatment of slurry after desulfurization - Google Patents
Treatment of slurry after desulfurizationInfo
- Publication number
- JPH02152518A JPH02152518A JP63303918A JP30391888A JPH02152518A JP H02152518 A JPH02152518 A JP H02152518A JP 63303918 A JP63303918 A JP 63303918A JP 30391888 A JP30391888 A JP 30391888A JP H02152518 A JPH02152518 A JP H02152518A
- Authority
- JP
- Japan
- Prior art keywords
- slurry
- thickener
- gypsum
- particles
- absorption
- 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.)
- Pending
Links
- 239000002002 slurry Substances 0.000 title claims abstract description 45
- 238000006477 desulfuration reaction Methods 0.000 title claims description 20
- 230000023556 desulfurization Effects 0.000 title claims description 20
- 239000002562 thickening agent Substances 0.000 claims abstract description 33
- 229910052602 gypsum Inorganic materials 0.000 claims abstract description 27
- 239000010440 gypsum Substances 0.000 claims abstract description 27
- 235000019738 Limestone Nutrition 0.000 claims abstract description 13
- 239000006028 limestone Substances 0.000 claims abstract description 13
- 239000006228 supernatant Substances 0.000 claims abstract description 13
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 12
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims abstract description 11
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims abstract description 9
- 239000007790 solid phase Substances 0.000 claims abstract description 5
- 238000010521 absorption reaction Methods 0.000 claims description 37
- 238000000034 method Methods 0.000 claims description 24
- 239000007788 liquid Substances 0.000 claims description 19
- 239000000428 dust Substances 0.000 claims description 11
- 239000007791 liquid phase Substances 0.000 claims description 10
- 239000011575 calcium Substances 0.000 claims description 7
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 235000010261 calcium sulphite Nutrition 0.000 claims description 4
- GBAOBIBJACZTNA-UHFFFAOYSA-L calcium sulfite Chemical compound [Ca+2].[O-]S([O-])=O GBAOBIBJACZTNA-UHFFFAOYSA-L 0.000 claims description 3
- 238000004065 wastewater treatment Methods 0.000 claims description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 2
- 235000011121 sodium hydroxide Nutrition 0.000 claims 1
- 239000010802 sludge Substances 0.000 abstract description 17
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 abstract description 16
- 239000002245 particle Substances 0.000 abstract description 15
- 239000007787 solid Substances 0.000 abstract description 10
- 229910000019 calcium carbonate Inorganic materials 0.000 abstract description 8
- 239000006227 byproduct Substances 0.000 abstract description 6
- 229910052925 anhydrite Inorganic materials 0.000 abstract description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 abstract description 3
- 238000002425 crystallisation Methods 0.000 abstract description 2
- 230000008025 crystallization Effects 0.000 abstract description 2
- 235000010216 calcium carbonate Nutrition 0.000 abstract 3
- 235000017550 sodium carbonate Nutrition 0.000 abstract 2
- 239000011362 coarse particle Substances 0.000 abstract 1
- 239000012071 phase Substances 0.000 abstract 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 9
- 238000004062 sedimentation Methods 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000007789 gas Substances 0.000 description 7
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 5
- 235000011149 sulphuric acid Nutrition 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 229910052815 sulfur oxide Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000003672 processing method Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 229940043430 calcium compound Drugs 0.000 description 1
- 150000001674 calcium compounds Chemical class 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000011268 mixed slurry Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 239000012066 reaction slurry Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
Landscapes
- Treating Waste Gases (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、カルシウム系吸収液を用いる吸収塔内の吸収
スラリに空気を供給し亜硫酸カルシウムを酸化して硫酸
カルシウム（石膏）として回収する脱硫方法に係り、特
に、軟化処理後の固形分の沈降性を高めるのに好適な脱
硫スラリの処理方法に関する。Detailed Description of the Invention [Field of Industrial Application] The present invention is a desulfurization method in which air is supplied to an absorption slurry in an absorption tower using a calcium-based absorption liquid to oxidize calcium sulfite and recover it as calcium sulfate (gypsum). The present invention relates to a desulfurization slurry treatment method, and particularly to a desulfurization slurry treatment method suitable for increasing the settling properties of solid content after softening treatment.
カルシウム系吸収液を用いる湿式脱硫装置において、ボ
イラ等の排ガス中の硫黄酸化物（Ｓ Ｏ２が主体）を吸
収した吸収液は亜硫酸カルシウム（ＣａＳＯ３）を形成
し、一部は、さらに排ガス中に含まれる酸素（０□）に
より酸化されて、硫酸カルシウム（Ｃａ Ｓ Ｏ４１石
膏）を形成する。この反応スラリを、石膏回収工程にお
いてＰ）ｌを調整し、空気酸化を行った後面・液相を分
離し、固相分は脱水して付着水１０％以下の石膏として
回収する。一方、液相分は脱硫工程に戻して再利用する
ことによって脱硫装置からの排水量の低減をはかってい
るが、この液相には石膏が飽和状態で溶解しており、Ｐ
Ｈの変動、冷却、および、除じん工程で水の蒸発にとも
なう液の濃縮がある場合などにおいて、液中の溶解石膏
分が過飽和となって析出が起こり、該析出石膏が塔、タ
ンク、配管等に付着してスケールとなる。このため、該
液相分に炭酸ソーダ（Ｎ ａ−ＣＯ３）を添加して（１
）式の反応によりカルシウムイオン（Ｃａ２”）を炭酸
カルシウム（ＣａＣＯ３）として固定し、沈澱させるこ
とにより液相の軟化を行っている。In wet desulfurization equipment that uses a calcium-based absorption liquid, the absorption liquid absorbs sulfur oxides (mainly SO2) in the exhaust gas from boilers, etc., and forms calcium sulfite (CaSO3), some of which is further contained in the exhaust gas. It is oxidized by oxygen (0□) to form calcium sulfate (CaSO41 gypsum). In the gypsum recovery step, this reaction slurry is subjected to air oxidation, after which the P)l is adjusted and the liquid phase is separated, and the solid phase is dehydrated and recovered as gypsum with an adhering water content of 10% or less. On the other hand, the liquid phase is returned to the desulfurization process and reused to reduce the amount of water discharged from the desulfurization equipment, but this liquid phase contains saturated gypsum and P.
When the liquid is concentrated due to fluctuations in H, cooling, and water evaporation during the dust removal process, the dissolved gypsum in the liquid becomes supersaturated and precipitation occurs, and the precipitated gypsum is deposited in towers, tanks, and piping. etc., and forms scale. For this purpose, sodium carbonate (Na-CO3) was added to the liquid phase (1
The liquid phase is softened by fixing calcium ions (Ca2'') as calcium carbonate (CaCO3) and precipitating it by the reaction of the following formula.
Ｃａ” ＋ＳＯニー＋Ｎａ二Ｃｏ、−＊ＣａＣ０ｊ＋
２Ｎａ ＋ｓｏ４ −・曲（１）この際、固定したＣ
ａＣ０，が微細な粒子状で液相中に存在しているため、
その沈降分離に困難性があった。Ca” +SOney+Na2Co, -*CaC0j+
2Na +so4 -・Song (1) At this time, fixed C
Since aC0, exists in the liquid phase in the form of fine particles,
There were difficulties in its sedimentation separation.
以下、上記従来技術の方法の手順について、第２図によ
って、やや詳細に説明する。Hereinafter, the procedure of the above-mentioned prior art method will be explained in some detail with reference to FIG.
ボイラ等からの排ガスは、まず、ダクト１０を経て除じ
ん塔１に導かれ、導管１０１を経て供給される除じん塔
循環液によって除じんと同時に冷却される。この冷却さ
れた除じん排ガスはダクト１１を経て吸収塔２に導かれ
、導管１０５を経て供給される吸収塔循環液により硫黄
酸化物が吸収、除去されて、清浄な脱硫処理ガスとして
、ダクト１２を経て、大気中に放出される。Exhaust gas from a boiler or the like is first led to the dust removal tower 1 through a duct 10, and is cooled while being removed by the dust removal tower circulating fluid supplied through a conduit 101. This cooled dust-removed exhaust gas is led to the absorption tower 2 through the duct 11, and the sulfur oxides are absorbed and removed by the absorption tower circulating fluid supplied through the conduit 105, and the sulfur oxide is removed as a clean desulfurized gas through the duct 12. It is then released into the atmosphere.
除じん塔１からはばいじんを含有する除じん塔循環液の
一部がばいじん捕集量に応じて抜き出され、導管１００
および１０２を経て、排水処理装置９に送られる。A part of the dust-removing tower circulation liquid containing soot and dust is extracted from the dust removal tower 1 according to the amount of dust collected, and is passed through the conduit 100.
and 102, and then sent to the wastewater treatment device 9.
吸収塔２には、石灰石（ＣａＣＯ，）１３が送入される
石灰石スラリ槽３から、硫黄酸化物吸収量に応じて１石
灰石スラリか導管１０３を経て供給される。吸収塔２で
反応し、生成したＣａ５Ｏ，。The absorption tower 2 is supplied from a limestone slurry tank 3 into which limestone (CaCO, ) 13 is fed via a conduit 103 depending on the amount of sulfur oxides absorbed. Ca5O, produced by reaction in absorption tower 2.
Ｃａ５Ｏ，および未反応Ｃａ ＣＯ、からなるスラリは
、吸収塔での吸収硫黄酸化物量に応じて抜き出され、導
管１０４および１０６を経て反応槽１８に送られる。反
応槽１８では、硫酸（Ｈ２ＳＯ４）２０の添加により、
上記混合スラリ中の未反応Ｃａ ＣＯＪをＣａＳＯ４と
し、スラリｐＨを４．５〜５として導管１０７を経て酸
化塔１９に送る。酸化塔１９では、スラリ中のＣａ Ｓ
Ｏ３が供給空気１４によって酸化されＣａＳＯ４とな
り、スラリ中の固形物がすべてＣａＳＯ４２なるので、
これを導管１０８を経て石膏シックナ４に送り、固・液
を分離し、濃縮固形物は脱水器５により脱水して、Ｃａ
５０４（石膏）１７を副生じ、−方、脱水操作で得られ
る液相分は導管１１１を経て石膏シックナ４に還流する
。ここで、シックナ４の上澄液はＣａ５Ｏ，が飽和状態
で溶解している液であり、そのままではｐＨの変動ある
いは液の濃縮等によってＣａ５Ｏ，がスケールとして配
管等に析出するので、これを軟化処理槽６に送り、ここ
でＮａ２Ｃｏ、および／または力性ソーダ（ＮａＯＨ）
１５を添加して溶解Ｃａ５Ｏ，を粒状析出させ、さらに
、沈降、濃縮に適したフロックとするため凝集剤１６を
添加し、調質スラリとして導管１１３を経てスラッジシ
ックナ７に送る。スラッジシックナ７では固・液相を分
離し、上澄液は導管１１４および１１５、１１６．１１
７を経由して除じん塔ｌ、吸収塔２および石灰石スラリ
槽３に送って補給水として再利用し、一方、ＣａＣ０，
を主成分とする濃縮固形分はスラッジタン７．８および
導管２００および２０１、２０２．２０３を経て石灰石
スラリ槽３１反応槽１８および吸収塔２に送り、ＣａＣ
０，源として再利用するという手順である。A slurry consisting of Ca5O and unreacted Ca2CO is extracted in accordance with the amount of sulfur oxide absorbed in the absorption tower and sent to reaction vessel 18 via conduits 104 and 106. In the reaction tank 18, by adding 20 sulfuric acid (H2SO4),
The unreacted Ca COJ in the mixed slurry is made into CaSO4, the slurry pH is adjusted to 4.5 to 5, and the slurry is sent to the oxidation tower 19 via the conduit 107. In the oxidation tower 19, CaS in the slurry
O3 is oxidized by the supply air 14 to become CaSO4, and all the solids in the slurry become CaSO42, so
This is sent to the gypsum thickener 4 through the conduit 108 to separate solids and liquids, and the concentrated solids are dehydrated by the dehydrator 5 to remove Ca.
504 (gypsum) 17 is produced as a by-product, and on the other hand, the liquid phase obtained by the dehydration operation is returned to the gypsum thickener 4 via a conduit 111. Here, the supernatant liquid of thickener 4 is a liquid in which Ca5O is dissolved in a saturated state, and if left as it is, Ca5O will precipitate as scale on piping etc. due to pH fluctuations or concentration of the liquid, so it is necessary to soften it. It is sent to a treatment tank 6 where Na2Co and/or sodium hydroxide (NaOH) is added.
15 is added to precipitate dissolved Ca5O in granular form, and further, a flocculant 16 is added to form a floc suitable for sedimentation and concentration, and the slurry is sent to the sludge thickener 7 via a conduit 113 as a tempered slurry. The sludge thickener 7 separates solid and liquid phases, and the supernatant liquid is passed through conduits 114 and 115, 116.11.
7 to the dust removal tower 1, absorption tower 2, and limestone slurry tank 3 to be reused as make-up water.
Concentrated solids mainly composed of CaC
0, the procedure is to reuse it as a source.
しかしながら、この方式の場合、軟化処理槽６で形成さ
れるＣａＣＯ，は前述の通り微細であることから、スラ
ッジシックナ７内で沈降を行わせるためには、該シック
ナ７内に長時間滞留させる必要があり、大容量のシック
ナの設置を必要としていた。However, in the case of this method, since the CaCO formed in the softening treatment tank 6 is fine as described above, it is necessary to stay in the sludge thickener 7 for a long time in order to cause the CaCO to settle therein. Therefore, it was necessary to install a large-capacity thickener.
また、上記の方式以外に、吸収塔内で排ガス中のＳＯ２
を吸収するとともに該吸収塔の下部タンク部に空気を吹
き込み、吸収スラリ中のＣａＳ○。In addition to the above method, SO2 in the exhaust gas is
At the same time, air is blown into the lower tank part of the absorption tower to remove CaS○ in the absorption slurry.
を酸化することによって酸化塔の設置を省略する方式や
、吸収スラリに酸化触媒を添加し、ボイラ排ガス中に含
まれる酸素を利用して、特に空気吹き込みを行うことな
く、吸収スラリ中のＣａ５Ｏｚを酸化してＣａ５Ｏ，と
する方式（特公昭筒５８−２０８８８号）などが、これ
までに提案されている。Ca5Oz in the absorption slurry can be removed by adding an oxidation catalyst to the absorption slurry and using the oxygen contained in the boiler exhaust gas without blowing air. A method of oxidizing to Ca5O (Japanese Patent Publication No. 58-20888) has been proposed so far.
これらの方式においては吸収スラリ中に残留している未
反応ＣａＣ０，をＨ２ＳＯ４との反応によってＣａ５Ｏ
，とじて除去する方法をとっているため、副生ＣａＳＯ
４への未反応ＣａＣ０，の混入を防止するための工夫が
必要となる。その−例を第３図に示す。この場合は、吸
収塔２の下部の液に導管１０７を経て空気１４を吹き込
む方法によるもので、吸収スラリはＣａＳＯ４と未反応
のＣａＣ０，とを含むスラリとなり、導管１０６を経て
反応槽１８に送られ、Ｈ２ＳＯ４添加が添加され、
ＣａＣＯ３＋Ｈ２ＳＯ４＋Ｈ２Ｏ−＋ＣａＳＯ４・２Ｈ
２０＋ＣＯ２・・・・・・（２）の反応によって未反応
Ｃａ ＣＯＪがＣａＳＯ４２Ｈ２０（２水石膏）となり
、シックナ４で濃縮された後、副生石膏１７として回収
される。この場合にも、シックナ４の上澄液は前記第２
図の装置を用いた場合と同様の方法で軟化処理されるも
のであり、従って、スラッジシックナ７はやはり大容積
のものが必要となっていた。In these methods, unreacted CaC0 remaining in the absorption slurry is converted to Ca5O by reaction with H2SO4.
, by-product CaSO
It is necessary to devise ways to prevent unreacted CaC0 from being mixed into 4. An example of this is shown in FIG. In this case, air 14 is blown into the liquid at the bottom of the absorption tower 2 through the conduit 107, and the absorbed slurry becomes a slurry containing CaSO4 and unreacted CaC0, and is sent to the reaction tank 18 through the conduit 106. and H2SO4 addition is added, CaCO3 + H2SO4 + H2O- + CaSO4.2H
20+CO2... (2) Unreacted Ca COJ becomes CaSO42H20 (dihydrate gypsum), which is concentrated with thickener 4 and then recovered as by-product gypsum 17. In this case as well, the supernatant liquid of the thickener 4 is
The softening process is performed in the same manner as in the case of using the apparatus shown in the figure, and therefore, the sludge thickener 7 still needs to have a large volume.
上記したように、従来技術においては軟化処理後の固形
物分離の迅速化について配慮されていなかったため、大
容量のスラッジシックナの設置と固形物分離促進のため
の凝集剤の添加が必要となっていた。As mentioned above, in the conventional technology, no consideration was given to speeding up the separation of solids after the softening process, which necessitated the installation of a large-capacity sludge thickener and the addition of a flocculant to promote solids separation. Ta.
本発明の目的は、上記従来技術の有していた課題を解決
し、軟化処理後の固形物分離の迅速化をはかり、スラッ
ジシックナ容量の縮小を可能とし。The object of the present invention is to solve the problems of the above-mentioned prior art, speed up the separation of solids after softening treatment, and make it possible to reduce the capacity of the sludge thickener.
また、凝集剤添加を軽減あるいは省略することのできる
脱硫スラリの処理方法を提供することにある。Another object of the present invention is to provide a method for treating desulfurization slurry that can reduce or omit the addition of a flocculant.
上記目的は、吸収スラリ中の未反応ＣａＣ０゜（吸収ス
ラリ中に１〜ｌｏｍ−ｍｏＱ／Ｑ含まれる）を、Ｈ２Ｓ
Ｏ４添加による中和処理を施すことなく、石膏シックナ
に送り、該シックナの上澄液中にＣａ ＣＯ、粒子を残
存させた状態で、さらに、軟化処理槽に送ることによっ
て達成することができろ。The above purpose is to remove unreacted CaC0° (contained from 1 to lom-moQ/Q in the absorption slurry) in the absorption slurry to H2S
This can be achieved by sending it to a gypsum thickener without performing neutralization treatment by adding O4, leaving Ca CO and particles in the supernatant liquid of the thickener, and then sending it to a softening treatment tank. .
吸収スラリ中の未反応ＣａＣＯ３の粒径は５〜２〇−で
、同じく吸収スラリ中に形成、存在しているＣａＳＯ４
の粒径４０〜６０虜に比較して微細なため、石膏シック
ナにおいては上Ｋｌ液側に流出する。この上澄液中に流
出した微細Ｇ ａ ＣＯ、粒子が核となって、軟化処理
槽で前出（１）式の反応により新たに形成されるＣ ａ
ＣＯａがその表面に析出、結晶化する結果、ＣａＣ０
，粒子が巨大化し、スラッジシックナでの沈降を促進す
る働きをすることになる。The particle size of unreacted CaCO3 in the absorption slurry is 5 to 20-2, which is larger than the CaSO4 formed and present in the absorption slurry.
Since the particle size is finer than that of 40 to 60 particles, it flows out to the upper Kl liquid side in the gypsum thickener. The fine Ga CO and particles that flowed out into this supernatant become nuclei, and Ca is newly formed in the softening treatment tank by the reaction of formula (1) above.
As a result of COa precipitation and crystallization on the surface, CaC0
, the particles become large and act to promote sedimentation in the sludge thickener.
以下、本発明による脱硫スラリの処理方法について、実
施例によって具体的に説明する。Hereinafter, the method for treating desulfurization slurry according to the present invention will be specifically explained with reference to Examples.
第１図は本発明の方法の実施に用いる排煙脱硫装置の一
例を示す系統図である。FIG. 1 is a system diagram showing an example of a flue gas desulfurization apparatus used for carrying out the method of the present invention.
ここで、除じん塔１、吸収塔２、石灰石スラリ槽３およ
びその周辺の構成は従来方法の場合の装置（第２図、第
３図）と同様であるが、本発明の方法による場合、吸収
塔で空気供給による酸化処理を施した未反応Ｃａ ＣＯ
、を含む吸収スラリは、従来技術の方法のようなＦＩ２
Ｓ０４の添加を行うことなく、導管１０４．１０６を経
て、直接、石膏シックナ４に排出される。石膏シックナ
４において、粒径の大きいＣａ５Ｏ，粒子は迅速に沈降
し、脱水機５により脱水され、副生石膏として取り出さ
れる。Here, the configurations of the dust removal tower 1, absorption tower 2, limestone slurry tank 3, and their surroundings are the same as those in the conventional method (FIGS. 2 and 3), but in the case of the method of the present invention, Unreacted Ca CO subjected to oxidation treatment by air supply in the absorption tower
, an absorbent slurry containing FI2 as in prior art methods.
It is discharged directly to the gypsum thickener 4 via conduits 104, 106 without addition of S04. In the gypsum thickener 4, Ca5O particles with large particle diameters quickly settle, are dehydrated by the dehydrator 5, and are taken out as by-product gypsum.
一方、未反応ＣａＣＯ，は、粒径が小さいため、石膏シ
ックナの上澄液側に流出しており、導ｇｏｔを経て軟化
処理槽６に供給される。軟化処理槽６ではＮａ、Ｃｏ、
および／またはＮａＯＨ１５が添加され、ここで形成さ
れるＣａＣ０，はすでに上澄液中に分散、存在している
微細ＣａＣ０，粒子を核としてその表面に結晶化し、巨
人粒子となり、スラッジシックナ７１こ送られ、濃縮、
分離される。ａ縮されたスラッジの主成分はＣａ ＣＯ
ｊであり、導管２００、２０１．２０２等を経て吸収塔
２および／または石灰石スラリ槽３に送られ、再利用さ
れる。−力、スラジシックナの上１ｆｄｄｉは溶解カル
シウム分が少なく、硫酸ナトリウムを含んでいるが、導
管１１３゜１１５、１１６．１１４等を経て、除じん塔
１および／または吸収塔２および／または石灰石スラリ
槽３しこ送られ、その補給水として利用される。On the other hand, since the unreacted CaCO has a small particle size, it flows out to the supernatant liquid side of the gypsum thickener, and is supplied to the softening treatment tank 6 through the guide Got. In the softening treatment tank 6, Na, Co,
and/or NaOH15 is added, and the CaC0 formed here crystallizes on the surface of the fine CaC0 particles already dispersed and present in the supernatant, forming giant particles and being sent to the sludge thickener 71. concentrated,
Separated. The main components of a-condensed sludge are Ca CO
j, and is sent to the absorption tower 2 and/or limestone slurry tank 3 via conduits 200, 201, 202, etc., and is recycled. - The upper 1fddi of the sludge thickener has a low dissolved calcium content and contains sodium sulfate, but it is passed through conduits 113, 115, 116, 114, etc. to the dust removal tower 1 and/or absorption tower 2 and/or limestone slurry tank. The water is sent to three locations and used as supplementary water.
なお、吸収塔２内吸収スラリ中のＣａ ＣＯ、ａ度と脱
硫率との関係は第４図に示す通りで、高い脱硫率を得る
ためには、吸収スラリ中のｃ ａ ｃ Ｏ］ Ｌｆｌａ
度を５ ｍ−ｍｏ Ｑ ／ Ｑ前後としておくことが有
効であることがわかる。The relationship between Ca CO in the absorption slurry in the absorption tower 2, a degree and the desulfurization rate is as shown in Fig. 4, and in order to obtain a high desulfurization rate, it is necessary to
It can be seen that it is effective to set the degree to around 5 m-mo Q/Q.
また１発明者等が石膏シックナ４の上澄液中の残留Ｃａ
Ｃ０，４度を変えて軟化処理後の生成固形物の沈降速度
の試験を行った結果、第１表に示すような結果を得た。In addition, one inventor et al.
As a result of testing the sedimentation rate of the solids produced after the softening treatment by changing the C0.4 degrees, the results shown in Table 1 were obtained.
この結果から、吸収スラリ中にＣａＣ０，を残留させた
場合、軟化処理生成物の沈降速度を約８倍近く促進でき
る効果のあることがわかる。This result shows that when CaC0 remains in the absorption slurry, it has the effect of accelerating the sedimentation rate of the softened product by about 8 times.
第 １ 表
Ｐｉ（１０
また、吸収スラリ中のＣａ５０４ａ度は６００−９００
ｍ−ｍｏＱ／Ｑとなっており、これに対して吸収スラリ
中のＣａＣＯ３は全体のカルシウム化合物に対し０．６
〜０．９ｍｏＱ％であって、そのまま石膏シックナ４へ
排出しても、副生石膏純度に与える影響は極めて小さい
。Table 1 Pi (10 Also, the Ca504a degree in the absorption slurry is 600-900
m-moQ/Q, whereas CaCO3 in the absorption slurry is 0.6% of the total calcium compound.
~0.9moQ%, and even if it is discharged as it is to the gypsum thickener 4, the effect on the purity of by-product gypsum is extremely small.
なお、上記した本実施例の工程において、軟化処理の際
に、沈降をさらに促進するために、凝集剤１６を添加す
ることができることは言うまでもない。It goes without saying that in the process of this embodiment described above, a flocculant 16 can be added to further promote sedimentation during the softening treatment.
以上述べてきたように、脱硫スラリの処理方法を本発明
の方法とすることによって、従来技術の有していた課題
を解決して、軟化処理生成物の沈降を促進することがで
き、従って、スラッジシックナの容量を低減することが
できること、さらに、吸収スラリ中の残存ＣａＣ０，を
中和するためのＨ２ＳＯ４の添加を省略することができ
るという効果が得られる。As described above, by using the method of the present invention as a treatment method for desulfurization slurry, the problems of the prior art can be solved and the sedimentation of the softened treatment product can be promoted, and therefore, The following effects are obtained: the capacity of the sludge thickener can be reduced, and addition of H2SO4 for neutralizing residual CaC0 in the absorption slurry can be omitted.
なお、スラッジシックナの断面積は沈降分離すべき固有
物の沈降速度にほぼ比例するものであり、本発明の方法
を採用することによって、該シックナの断面積を従来技
術の方法を用いる場合の約１／８にコンパクト化するこ
とができることになる。Note that the cross-sectional area of the sludge thickener is approximately proportional to the sedimentation rate of the specific matter to be separated by sedimentation, and by employing the method of the present invention, the cross-sectional area of the thickener can be reduced to approximately This means that the size can be reduced to 1/8.
第１図は本発明の脱硫スラリの処理方法の実施に使用す
る脱硫装置の構成を示す系統図、第２図、第３図は従来
技術の脱硫スラリの処理方法の実施に使用する脱硫装置
の構成を示す系統図、第４図は吸収スラリ中のＣａＣ○
、ａ度と脱硫率との関係を示す図である。
１・・除じん塔 ２・・吸収塔
３・・石灰石スラリ槽 ４・石膏シックナ５・脱水機
６・・・軟化処理槽７・・・スラッジシックナ
８、スラッジタンク ９・・排水処理装置１０〜１２・
・ダクト １３・・・石灰石１４・空気
１５・・・炭酸ソーダおよび／あるいは力性ソーダ１６
・・・凝集剤 １７・・石膏１８・・反応槽
１９・・・酸化塔２０・・硫酸 １０
０〜１１８・・・導管２００〜２０３・・導管
代理人弁理上 中 村 純之助Fig. 1 is a system diagram showing the configuration of a desulfurization apparatus used to carry out the desulfurization slurry processing method of the present invention, and Figs. 2 and 3 show the desulfurization apparatus used to carry out the desulfurization slurry processing method of the prior art. A system diagram showing the composition, Figure 4 shows CaC○ in the absorption slurry.
, is a diagram showing the relationship between a degree and desulfurization rate. 1. Dust removal tower 2. Absorption tower 3. Limestone slurry tank 4. Gypsum thickener 5. Dehydrator
6... Softening treatment tank 7... Sludge thickener 8, sludge tank 9... Waste water treatment equipment 10-12.
・Duct 13...Limestone 14・Air 15...Soda carbonate and/or strength soda 16
...Flocculant 17..Gypsum 18..Reaction tank
19... Oxidation tower 20... Sulfuric acid 10
0-118...Conduit 200-203...Conduit agent attorney Junnosuke Nakamura
Claims (1)
に空気を供給し亜硫酸カルシウムを酸化して硫酸カルシ
ウム（石膏）として回収する脱硫装置において、石膏シ
ックナの上澄液に未反応石灰石を残留させ、該上澄液に
炭酸ソーダおよび／またはカ性ソーダおよび／または凝
集剤を添加して固・液相を分離し、固相分を石灰石スラ
リ槽および／または吸収塔に、液相分を吸収塔および／
または石灰石スラリ槽および／または除じん塔および／
または排水処理装置に供給することを特徴とする脱硫ス
ラリの処理方法。1. In a desulfurization equipment that supplies air to the absorption slurry in an absorption tower using a calcium-based absorption liquid to oxidize calcium sulfite and recover it as calcium sulfate (gypsum), unreacted limestone remains in the supernatant liquid of the gypsum thickener. , add soda carbonate and/or caustic soda and/or a flocculant to the supernatant liquid to separate solid and liquid phases, transfer the solid phase to a limestone slurry tank and/or absorption tower, and absorb the liquid phase. tower and/
or limestone slurry tank and/or dust removal tower and/or
Or a method for treating desulfurization slurry, characterized by supplying it to a wastewater treatment device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63303918A JPH02152518A (en) | 1988-12-02 | 1988-12-02 | Treatment of slurry after desulfurization |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63303918A JPH02152518A (en) | 1988-12-02 | 1988-12-02 | Treatment of slurry after desulfurization |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02152518A true JPH02152518A (en) | 1990-06-12 |
Family
ID=17926842
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63303918A Pending JPH02152518A (en) | 1988-12-02 | 1988-12-02 | Treatment of slurry after desulfurization |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02152518A (en) |
-
1988
- 1988-12-02 JP JP63303918A patent/JPH02152518A/en active Pending
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