【発明の詳細な説明】[Detailed description of the invention]
この発明はリン酸カルシウムを主成分とする脱
リン剤（リン鉱石、骨炭、リン酸カルシウムの各
結晶や、炭酸カルシウムやサンゴ化石の表面にリ
ン酸カルシウムを析出させたものなど）の結晶種
で処理塔内に接触層を形成し、リン酸塩を含む原
水を処理塔に上向流で通水することにより接触層
を流動化し、水中のリン酸イオンを結晶種に晶析
させて除去する流動床式晶析脱リン装置に関す
る。
この様な脱リン装置を本特許出願人は特願昭57
−103895号（特開昭58−223478公報）、特願昭58
−30889号（特開昭59−156487公報）で提案し
た。特願昭57−103895号は接触層に原水を下向流
で通水し、接触層を固定床として処理を行つてい
た従来の問題点を、原水を上向流で通水して接触
層を流動床として処理を行う様に改良したもので
あり、又、特願昭58−30889号は流動床式で処理
する場合、時間の経過により結晶種が肥大化して
流動床が膨張し、結晶種が処理水に混入すると共
に、水質をも悪化させるのを、流動床の界面の検
出や、流動床の圧力損失を測定することによつて
流動床の膨張量を感知し、結晶種の抜出量を制御
して流動する種結晶の粒子量を一定以下に保ち、
水質の悪化を防止する様にしたものである。
晶析反応によつて結晶種の表面に析出し、結晶
種を肥大化させるリン酸カルシウムに付いて詳細
に検討すると、リン酸カルシウムの結晶はポーラ
スに成長するため、結晶種の液中におけるみかけ
比重（湿潤比重）は低下し、原水の上向流の通水
で流動する際は肥大化し、粒径の増大により沈降
速度が大きくなる現象に反して湿潤比重の低下の
効果が大きく、みかけの沈降速度が減少し、流動
床の上部に移行し易くなることを見出した。
これは結晶種に調和平均粒径0.32mm（粒径0.25
〜0.45mm）のリン鉱石を用い、原水には市水にリ
ン酸＝水素ナトリウム、重炭酸ソーダ、塩化カル
シウム溶液を加えてＰ＝２mg／、Ｍ−アルカリ
度＝100mg／、Ca＝45mg／となる様に調整
し、これにNaOH溶液を加えてPH＝９とした合成
水を用い、直径30mm、高さ1000mmの透明アクリル
カラムに上記結晶種を約200ml充填し、上記合成
原水をカラムに通水線度約10ｍ／hrで上向流さ
せ、60日後に結晶種の粒径、湿潤比重を測定した
下表の結果でも明らかである。
This invention uses crystal seeds of a dephosphorizing agent whose main component is calcium phosphate (phosphate rock, bone char, calcium phosphate crystals, calcium carbonate, calcium phosphate precipitated on the surface of coral fossils, etc.) to create a contact layer in the treatment tower. In fluidized bed crystallization desorption, the raw water containing phosphate is passed through the treatment tower in an upward flow to fluidize the contact layer, and the phosphate ions in the water are crystallized into crystal seeds and removed. Concerning phosphorus equipment. The applicant of this patent filed a patent application for such a dephosphorization device in 1982.
-103895 (Japanese Unexamined Patent Application Publication No. 1983-223478), Patent Application No. 1983
This was proposed in No. 30889 (Japanese Unexamined Patent Publication No. 59-156487). Japanese Patent Application No. 57-103895 solves the conventional problems of passing raw water through the contact layer in a downward flow and treating the contact layer as a fixed bed by passing the raw water in an upward flow and contacting the contact layer. The bed has been improved to be treated as a fluidized bed, and Japanese Patent Application No. 58-30889 discloses that when processing in a fluidized bed type, the crystal seeds become enlarged over time and the fluidized bed expands. The amount of expansion of the fluidized bed can be detected by detecting the interface of the fluidized bed and measuring the pressure loss of the fluidized bed, and the amount of expansion of the fluidized bed can be detected to prevent crystal seeds from getting mixed into the treated water and deteriorating the water quality. By controlling the extraction amount and keeping the amount of flowing seed crystal particles below a certain level,
This is to prevent deterioration of water quality. A detailed study of calcium phosphate, which precipitates on the surface of crystal seeds through a crystallization reaction and enlarges them, reveals that since calcium phosphate crystals grow porous, the apparent specific gravity (wet specific gravity) in the liquid of crystal seeds is ) decreases, and when flowing through upward flow of raw water, they become enlarged, and contrary to the phenomenon that the sedimentation rate increases due to the increase in particle size, the effect of lowering the wet specific gravity is large, and the apparent sedimentation rate decreases. However, it was found that it becomes easier to migrate to the upper part of the fluidized bed. This has a harmonic mean grain size of 0.32mm (grain size 0.25mm) for crystal seeds.
Using phosphate rock (~0.45mm), add phosphoric acid = sodium hydrogen, sodium bicarbonate, and calcium chloride solution to city water so that P = 2 mg /, M - alkalinity = 100 mg /, Ca = 45 mg /. Using synthetic water adjusted to PH=9 by adding NaOH solution to it, approximately 200 ml of the above crystal seeds was packed into a transparent acrylic column with a diameter of 30 mm and a height of 1000 mm, and the synthetic raw water was passed through the column through the water line. This is also clear from the results shown in the table below, in which the grain size and wet specific gravity of the crystal seeds were measured after 60 days of upward flow at a rate of approximately 10 m/hr.
【表】
尚、終端速度Utはストークスの沈降速度式
Ut＝（ρｐ−ρ）Ｄｐ ２・ｇ／１８μ
但しρp＝粒子の密度（Kg／m3）
Ｄp＝粒子の直径（ｍ）
ρ＝流体の密度（Kg／m3）
μ＝粘度（Kg／ｍ−ｓ）
より求めた。
つまり、60日後には粒径も増大し、真比重も増
加しながら湿潤比重は低下し、その結果終端速度
も低下するのである。そして、この肥大した結晶
種の液との接触面積は、集合すると同大になる小
さい結晶種の複数の合計接触面積よりも小さいの
で、脱リン効率は小さい。
第１図は結晶種を粒度毎に選別して脱リン処理
を行つた場合の除去率を示すもので、調和平均径
0.1〜0.35mmのものゝ脱リン率が良好で、特に0.2
mmが最も高い。従つて流動床に供給する脱リン剤
の径はこの範囲内とする。調和平均径がそれより
大きなものゝリン除去率が低いのは液との接触面
積が減少するためである。尚、第１図に付いての
詳細ならびに、結晶種が使用によつて肥大する機
構は特願昭58−116058号（特開昭60−7992号公
報）の記載を参照されたい。
前述した各先行出願では塔内で使用している結
晶種の膨張を元の状態に無くし、且つ入れ換える
ために原水の上向流を中止し、処理塔の下端から
塔内の水を抜出すことによつて接触層を構成して
いる結晶種を、多段式の場合は相互に上段から下
段に一部移動させると共に最下段の一部を外に取
出し、賦活して最上段に供給しているが、これで
は、湿潤比重が低下し、接触層の主に上層に居る
肥大した結晶種は外に取出しにくゝ、各段の接触
層の結晶種は肥大したものが次第に多くなる。
そこで本発明は原水を上向流させての運転中
に、流動化している流動床の上面レベル上で乱舞
する主に湿潤比重の低下した肥大結晶種をダウン
カマーで塔外に抜取ることにより上述の問題点を
解消したのであつて、以下、図示の一実施例を参
照して本発明を説明する。
第２図は前述の先行特許出願（特願昭57−
103895、同58−30889）と同様な多段の流動床式
脱リン装置に実施した発明の一実施例であつて、
処理塔１内には最下段の支持板２′を除き安息角
ノズルと非安息角ノズルを取付けた支持板２を多
段に設け、最下段の支持板２′には安息角ノズル
だけを取付け、各支持板上には脱リン剤の結晶種
の接触層３を構成する。
運転を行うには最上段の接触層３に新品或いは
再生した結晶種を供給管４で連続的或いは間欠的
に供給し、原水を給水管５で最下段の支持板２′
の下に給水して各支持板のノズルを通じ塔内を上
向流させ、各段の接触層を構成する結晶種を乱舞
状態に流動させ、水中のリン酸イオンが晶析反応
にて除去された処理水を塔の上端の溢流堰６に得
る。尚、運転中には給水管５を流れる原水に薬注
装置７……………でカルシウム剤、アルカリ剤、
晶析促進剤（例えば塩素剤、弗化物など）を注入
し、又、必要に応じ薬注装置７……………で各段
の流動床中にもカルシウム剤、アルカリ剤、晶析
促進剤を注入する。
こうして運転を継続すると各段の接触層の結晶
種は肥大すると共に、表面にリン酸カルシウムが
析出した微細粒子も混在する様になつて接触層は
膨張し、特に最上段の接触層は供給管４で連続的
或いは間欠的に新品又は再生した結晶種が補給さ
れるので最も膨張する。
このため最上段の接触層の流動している上面を
レベルスイツチや圧力上昇などで検出し、その値
が一定以上になつたら原水の給水を停止し、塔下
端の抜出管８の弁を開き、塔内の水を各段支持板
の安息角ノズル及び非安息ノズルの孔を通じ下向
流させ、この水に随伴させて相互に上段の接触層
の一部を下段に移動させると共に、最下段の接触
層の結晶種は最下段の支持板の安息角ノズルの孔
を通じ塔外に一部抜出す。これにより各段の支持
板上の結晶種の量が或る程度減少したら塔内の水
の下向流を止め静置する。すると最下段の支持板
を除き、それよりも上の各支持板に取付けてある
非安息角ノズルを通じ相互に上段の結晶種中、非
安息角ノズルの近傍に居る一部が下段に落下し、
最上段の接触層の結晶種の量と、それ以外の各段
の接触層の結晶種の量はほゞ等しくなるので、そ
れから運転を再開する。
上記した運転の詳細は特に先行特許出願の特に
特願昭57−103895号に詳説したので、詳細はそれ
を参照されたい。
さて前述した様に原水の給水を停止し、抜出管
８から塔内の水を抜いて相互に上段の接触層の結
晶種の一部を下段に移動させ、下段の接触層の結
晶種の一部を塔外に取出しても、湿潤比重が低下
した肥大結晶種は接触層の上部に存在するため下
段に移動したり、塔外に取出されることが少な
い。このため本発明は原水を上向流で通水し、接
触層を流動化させている際に、流動床の予定上面
或いはそれも少し上に上端を位置させてダウンカ
マー（抜取管）９を塔の側壁に貫通して設けたの
である。
接触層が多段にある場合は、この実施例の様に
ダウンカマーは各段の接触層毎に設けるのが最も
好ましいが、必ずしもその必要はなく、一つ置き
など一部の接触層に設けるだけでもよい。そし
て、ダウンカマーには夫々手動操作或いは自動操
作の弁などの開閉手段９′を付属させる。
従つて、運転中にタイマーなどで定期的に一定
時間ダウンカマーの開閉手段を開にしたり、ダウ
ンカマーの上端よりも上方の塔内部に界面検出セ
ンサーを設置し、そのセンサーが結晶種を検出し
たときに発する信号でダウンカマーの開閉手段を
開にしたり、或いは塔壁に覗き窓を設け、こゝか
ら塔内を透視してダウンカマーの上端よりも上で
乱舞する結晶種が多くなつたら手操作で開閉手段
を開にしたりして、流動している結晶種の一部を
塔外に抜取ることができ、抜取られる結晶種は主
に肥大した、湿潤比重の小さいものであるため、
接触層の結晶種が次第に肥大したものが多くなる
と言う現象を防ぎ、効果的に脱リンを行うことが
できる。
又、この様にしてダウンカマーで流動床の上部
或いは上方の結晶種を塔外に取出し、膨張を幾分
とも減らすので、最上段への新品、再生結晶種の
補給量にもよるが、塔内の結晶種を一部宛入れ換
え、且つ膨張を元の状態になくするために運転を
中断する間隔は従来より長くでき、運転効率を高
めることができる。
そして、ダウンカマーで抜取つた結晶種及び液
は、この実施例では入換えのために最下段の接触
層から抜出した結晶種をも入れる共通の貯槽１０
に受け、液は原水として給水管５に戻し、結晶種
は機械的に破砕、表面剥離などしたり、化学的に
酸処理して表面を溶解したりする細粒化加工手段
１１を経て分級機１２、例えばハイドロサイクロ
ン、スクリーンを用いた湿式篩分け機、沈降分離
槽でリン除去率が高い調和平均径0.1〜0.35mm、
好ましくは最も高い調和平均径0.2mmのものを分
級し、これを好ましくはアルカリ処理、酸処理、
次亜塩素酸ソーダ処理、加温処理の一種又は二種
以上の組合せを行う再活性化槽１３に供給して賦
活した後、供給管４で最上段の接触層に供給す
る。尚、分級機で生じた調和平均径以下のものは
回収する。
こうして本発明によれば使用により肥大化した
結晶種が湿潤比重を低下し、流動床の上方で流動
することに着目し、主としてこれをダウンカマー
で塔外に抜取つて接触層の膨張を抑制し、脱リン
効率のよい粒径の結晶種によつて効率よく脱リン
を行うと共に、塔内の結晶種を入換えるための運
転中断間隔を延長し、装置の運転効率を高めるこ
とができる。
尚、図示の実施例は多段式であるが本発明は接
触層が一段の単段式のものにもそのまゝ適用でき
ることは言う迄もない。[Table] The terminal velocity Ut is determined by the Stokes sedimentation velocity equation Ut = (ρ p - ρ) D p 2・g/18μ where ρ p = particle density (Kg/m 3 ) D p = particle diameter (m ) ρ = fluid density (Kg/m 3 ) μ = viscosity (Kg/m-s). In other words, after 60 days, the particle size increases, the true specific gravity increases, and the wet specific gravity decreases, and as a result, the terminal velocity also decreases. Since the contact area of the enlarged crystal seeds with the liquid is smaller than the total contact area of a plurality of small crystal seeds that become the same size when aggregated, the dephosphorization efficiency is low. Figure 1 shows the removal rate when dephosphorization is performed by sorting crystal seeds by particle size, and shows the harmonic mean diameter.
0.1 to 0.35 mm has a good dephosphorization rate, especially 0.2
mm is the highest. Therefore, the diameter of the dephosphorizing agent supplied to the fluidized bed should be within this range. The reason why the phosphorus removal rate is lower when the harmonic mean diameter is larger than that is because the contact area with the liquid is reduced. For details regarding FIG. 1 and the mechanism by which crystal seeds enlarge with use, please refer to Japanese Patent Application No. 116058/1982 (Japanese Unexamined Patent Publication No. 7992/1982). In each of the above-mentioned prior applications, in order to eliminate the expansion of the crystal seeds used in the tower and to replace them, the upward flow of raw water is stopped and the water inside the tower is extracted from the lower end of the treatment tower. In the case of a multi-stage system, part of the crystal seeds that make up the contact layer are moved from the upper stage to the lower stage, and a part of the bottom stage is taken out, activated, and supplied to the top stage. However, in this case, the wet specific gravity decreases, and the enlarged crystal seeds mainly present in the upper layer of the contact layer are difficult to take out, and the number of enlarged crystal seeds in the contact layer at each stage gradually increases. Therefore, the present invention aims to extract enlarged crystal seeds with a reduced wet specific gravity from the column using a downcomer, which dances wildly on the upper surface level of the fluidized bed during operation with raw water flowing upward. Having solved the above-mentioned problems, the present invention will now be described with reference to an embodiment shown in the drawings. Figure 2 shows the aforementioned prior patent application (Japanese Patent Application No. 1983-
103895, 58-30889), which is an embodiment of the invention implemented in a multistage fluidized bed dephosphorization device similar to
Inside the treatment tower 1, there are multiple support plates 2 equipped with angle-of-repose nozzles and non-angle-of-repose nozzles, except for the support plate 2' at the bottom, and only the angle-of-repose nozzles are attached to the support plate 2' at the bottom. A contact layer 3 for crystal seeds of the dephosphorizing agent is formed on each support plate. To carry out the operation, new or regenerated crystal seeds are continuously or intermittently supplied to the contact layer 3 on the uppermost stage through the supply pipe 4, and raw water is supplied through the water supply pipe 5 to the support plate 2' on the lowermost stage.
Water is supplied to the bottom of the column and allowed to flow upward through the nozzles of each support plate, causing the crystal seeds that make up the contact layer at each stage to flow in a turbulent state, and phosphate ions in the water are removed by a crystallization reaction. The treated water is obtained at the overflow weir 6 at the top of the tower. During operation, the raw water flowing through the water supply pipe 5 is supplied with calcium agents, alkaline agents, etc. by the chemical injection device 7.
Inject crystallization accelerators (e.g. chlorine agents, fluorides, etc.) and, if necessary, inject calcium agents, alkali agents, crystallization accelerators into the fluidized bed at each stage using chemical injection device 7. inject. If the operation continues in this way, the crystal seeds in the contact layer of each stage will enlarge, and the contact layer will expand as fine particles with calcium phosphate precipitated on the surface will also be mixed in. In particular, the contact layer of the top stage will be affected by the supply pipe 4. New or regenerated crystal seeds are continuously or intermittently replenished, resulting in maximum expansion. For this reason, the flowing upper surface of the contact layer at the top stage is detected using a level switch or pressure increase, and when the value exceeds a certain level, the supply of raw water is stopped, and the valve of the extraction pipe 8 at the bottom end of the tower is opened. , the water in the tower is made to flow downward through the holes of the angle of repose nozzle and the non-repose nozzle of each stage support plate, and accompanied by this water, a part of the contact layer of the upper stage is mutually moved to the lower stage, and a part of the contact layer of the upper stage is moved to the lower stage. A portion of the crystal seeds in the contact layer is extracted to the outside of the column through the hole of the angle of repose nozzle in the lowermost support plate. As a result, when the amount of crystal seeds on the support plates of each stage is reduced to a certain extent, the downward flow of water in the tower is stopped and the tower is allowed to stand still. Then, apart from the bottom support plate, a part of the crystal seeds in the upper layer near the non-repose angle nozzle falls to the lower layer through the non-repose angle nozzles attached to each support plate above it.
Since the amount of crystal seeds in the contact layer at the top level is approximately equal to the amount of crystal seeds in each of the other contact layers, operation is restarted. The details of the above-mentioned operation are particularly explained in the prior patent application, especially Japanese Patent Application No. 103895/1983, so please refer to that for details. Now, as mentioned above, the supply of raw water is stopped, the water in the tower is drained from the extraction pipe 8, and some of the crystal seeds in the upper contact layer are transferred to the lower layer, and the crystal seeds in the lower contact layer are removed. Even if a portion is taken out of the tower, the enlarged crystal seeds whose wet specific gravity has decreased are present in the upper part of the contact layer, so they are unlikely to move to the lower stage or be taken out of the tower. Therefore, in the present invention, when raw water is passed through in an upward flow to fluidize the contact layer, the downcomer (sampling pipe) 9 is positioned with its upper end positioned at or slightly above the planned upper surface of the fluidized bed. It was installed through the side wall of the tower. When there are multiple contact layers, it is most preferable to provide a downcomer for each contact layer as in this example, but it is not always necessary to provide a downcomer for every other contact layer. But that's fine. Each downcomer is attached with an opening/closing means 9' such as a manually operated or automatically operated valve. Therefore, during operation, the opening/closing means of the downcomer is periodically opened for a certain period of time using a timer, or an interface detection sensor is installed inside the tower above the top of the downcomer, and the sensor detects the crystal seeds. The downcomer's opening/closing means can be opened using a signal emitted from time to time, or a viewing window can be installed in the tower wall to look through the tower and take action if there are many crystal seeds dancing wildly above the top of the downcomer. By opening the opening/closing means, some of the flowing crystal seeds can be extracted outside the column, and the extracted crystal seeds are mainly enlarged ones with low wet specific gravity.
It is possible to prevent the phenomenon in which the number of crystal seeds in the contact layer gradually enlarges and to effectively perform dephosphorization. In addition, in this way, the crystal seeds at the top or upper part of the fluidized bed are taken out of the column using the downcomer, and the expansion is somewhat reduced. The interval at which operation is interrupted in order to replace some of the crystal seeds within and to restore the expansion to its original state can be made longer than in the past, making it possible to improve operational efficiency. In this embodiment, the crystal seeds and liquid taken out by the downcomer are stored in a common storage tank 10, which also holds the crystal seeds taken out from the contact layer at the bottom for replacement.
The liquid is returned to the water supply pipe 5 as raw water, and the crystal seeds are passed through a particle refining means 11 that mechanically crushes and peels the surface, or chemically treats with acid to dissolve the surface, and then passes through a classifier. 12. For example, a hydrocyclone, a wet sieving machine using a screen, or a settling tank with a harmonic mean diameter of 0.1 to 0.35 mm, which has a high phosphorus removal rate;
Preferably, those with the highest harmonic mean diameter of 0.2 mm are classified, and this is preferably subjected to alkali treatment, acid treatment,
After being supplied to a reactivation tank 13 that performs one or a combination of two or more of sodium hypochlorite treatment and heating treatment and activated, it is supplied to the uppermost contact layer through a supply pipe 4. In addition, those produced in the classifier with a harmonic mean diameter or less are collected. In this way, according to the present invention, attention is paid to the fact that the crystal seeds enlarged by use lower the wet specific gravity and flow above the fluidized bed, and are mainly extracted to the outside of the column using a downcomer to suppress the expansion of the contact layer. In addition to efficiently dephosphorizing using crystal seeds having a particle size with high dephosphorization efficiency, it is possible to extend the operation interruption interval for replacing the crystal seeds in the column, thereby increasing the operating efficiency of the apparatus. Although the illustrated embodiment is of a multi-stage type, it goes without saying that the present invention can also be applied to a single-stage type with a single contact layer.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は結晶種の粒径別の脱リン率を示す図
表、第２図は本発明の一実施例を示すフローシー
トで、図中、１は処理塔、３は流動床を構成する
接触層、４は結晶種の供給管、５は原水の給水
管、８は結晶種及び水の抜出管、９はダウンカマ
ーを示す。
Fig. 1 is a chart showing the dephosphorization rate according to the particle size of crystal seeds, and Fig. 2 is a flow sheet showing an example of the present invention. 4 is a supply pipe for crystal seeds, 5 is a supply pipe for raw water, 8 is a discharge pipe for crystal seeds and water, and 9 is a downcomer.