JP2002143639A - Method for treating ammonia gas - Google Patents

Method for treating ammonia gas

Info

Publication number
JP2002143639A
JP2002143639A JP2000343863A JP2000343863A JP2002143639A JP 2002143639 A JP2002143639 A JP 2002143639A JP 2000343863 A JP2000343863 A JP 2000343863A JP 2000343863 A JP2000343863 A JP 2000343863A JP 2002143639 A JP2002143639 A JP 2002143639A
Authority
JP
Japan
Prior art keywords
phosphoric acid
ammonia
absorption tower
aqueous solution
gas
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
Application number
JP2000343863A
Other languages
Japanese (ja)
Inventor
Tomoyuki Fuse
Kazutoshi Ichikawa
Katsuya Maruyama
Tadao Takeuchi
克也 丸山
一敏 市川
智之 布施
忠雄 竹内
Original Assignee
Kurita Water Ind Ltd
栗田工業株式会社
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 Kurita Water Ind Ltd, 栗田工業株式会社 filed Critical Kurita Water Ind Ltd
Priority to JP2000343863A priority Critical patent/JP2002143639A/en
Publication of JP2002143639A publication Critical patent/JP2002143639A/en
Pending legal-status Critical Current

Links

Classifications

    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

PROBLEM TO BE SOLVED: To reduce the consumption of phosphoric acid per ammonia absorbed in a liquid absorbent, and moreover, to highly remove ammonia in a method which absorbs and removes ammonia in gas as ammonium phosphate by allowing the ammonia-containing gas to contact with an absorbing solution of phosphoric acid-containing solution. SOLUTION: Raw gas is introduced into a first absorption tower 1 and is brought into contact with a first phosphoric acid-containing aqueous solution, a major part of the ammonium in the raw gas is absorbed and removed, the treated gas in the first absorption tower 1 is introduced into a second absorption tower 2 and is brought into contact with a second phosphoric acid-containing aqueous solution, and thereby remaining ammonium is absorbed and removed. PH of the second phosphoric acid-containing aqueous solution is lower than the pH of the first phosphoric acid-containing aqueous solution.

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、汚泥のコンポスト
化設備から発生する排ガス等のアンモニア含有ガスをリ
ン酸含有水溶液に吸収させて処理する方法に係り、特
に、この方法において、アンモニア除去率の向上とリン
酸消費量の低減を図る方法に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating an ammonia-containing gas such as an exhaust gas generated from a sludge composting facility by absorbing it into a phosphoric acid-containing aqueous solution. The present invention relates to a method for improving and reducing phosphoric acid consumption.
【0002】[0002]
【従来の技術】従来、汚泥のコンポスト化設備等から発
生する、アンモニアを含有する排ガスは、図2に示す如
く、吸収塔11に導入し、リン酸含有水溶液の吸収液と
向流接触させてアンモニアをリン酸アンモニウムとして
吸収液中に吸収させることにより処理されている。
2. Description of the Related Art Conventionally, an exhaust gas containing ammonia, which is generated from a sludge composting facility or the like, is introduced into an absorption tower 11 and brought into countercurrent contact with an absorption solution of a phosphoric acid-containing aqueous solution as shown in FIG. It is treated by absorbing ammonia as ammonium phosphate in the absorbing solution.
【0003】吸収塔11は、気液接触効率向上のための
充填材12が充填され、原ガスと吸収液とを向流接触さ
せるガス洗浄塔であり、原ガスはこの吸収塔11の下部
から導入され、塔上部の散水管13から散布される吸収
液と接触してアンモニアが吸収除去された後、処理ガス
は塔頂から排出される。
[0003] The absorption tower 11 is a gas washing tower filled with a filler 12 for improving gas-liquid contact efficiency and bringing the raw gas and the absorbing liquid into countercurrent contact with each other. After the ammonia gas is introduced and comes into contact with the absorbing liquid sprayed from the water spray pipe 13 at the top of the tower to absorb and remove ammonia, the processing gas is discharged from the top of the tower.
【0004】この吸収塔11の塔下部の循環槽14に
は、リン酸水溶液が供給され、原ガス中のアンモニアは
この吸収液中にリン酸アンモニウムとして吸収される。
循環槽14の吸収液はポンプPにより循環され、液中の
リン酸アンモニウム濃度が高められる。アンモニアの吸
収でリン酸アンモニウム濃度が高められた吸収液は循環
槽14から引き抜かれ、液体肥料として製品化される。
[0004] A phosphoric acid aqueous solution is supplied to a circulation tank 14 at the lower part of the absorption tower 11, and ammonia in the raw gas is absorbed as ammonium phosphate in the absorption liquid.
The absorption liquid in the circulation tank 14 is circulated by the pump P, and the concentration of ammonium phosphate in the liquid is increased. The absorption liquid whose ammonium phosphate concentration has been increased by the absorption of ammonia is withdrawn from the circulation tank 14 and commercialized as a liquid fertilizer.
【0005】上記従来のアンモニア含有ガスの処理方法
により、吸収液のpHを4〜7の範囲で変えて、アンモ
ニア濃度200〜300ppmの原ガスを処理したとき
の、吸収液のpHと処理ガスのアンモニア濃度及び液体
肥料として抜き出される吸収液のリン濃度と窒素濃度と
の比(以下「P/N比」と称す。)との関係は表1に示
す通りである。
According to the above-described conventional method for treating an ammonia-containing gas, when the pH of the absorbing solution is changed in the range of 4 to 7 and the raw gas having an ammonia concentration of 200 to 300 ppm is treated, the pH of the absorbing solution and the processing gas Table 1 shows the relationship between the ammonia concentration and the ratio between the phosphorus concentration and the nitrogen concentration of the absorbent extracted as the liquid fertilizer (hereinafter referred to as “P / N ratio”).
【0006】[0006]
【表1】 [Table 1]
【0007】この結果から、吸収液のpHを4以下に設
定すれば、処理ガスのアンモニア濃度を0にすることが
できることがわかる。これは、ガス中のアンモニアは、
リン酸水溶液に酸−アルカリ反応で吸収されることに基
き接触時間を十分に確保した場合、ガス中のアンモニア
と吸収液中のアンモニアとの間には気液平衡が成り立
ち、吸収液のpHが低いほど、ガス中のアンモニア濃度
は低くなることによる。
[0007] From these results, it can be seen that the ammonia concentration of the processing gas can be reduced to 0 by setting the pH of the absorbing solution to 4 or less. This is because the ammonia in the gas
If the contact time is sufficiently ensured based on the absorption in the aqueous phosphoric acid solution by the acid-alkali reaction, a gas-liquid equilibrium is established between the ammonia in the gas and the ammonia in the absorbing solution, and the pH of the absorbing solution is increased. The lower the lower, the lower the ammonia concentration in the gas.
【0008】また、吸収液のpHによって、吸収液のP
/N比が変化し、pHが低いほどこの値が大きくなる。
即ち、吸収したアンモニアに対するリン酸使用量が多く
なることがわかる。これは、吸収液のpHを低く維持す
るためにはリン酸を大量に使用する必要があるからであ
る。
Further, depending on the pH of the absorbing solution, P
This value increases as the / N ratio changes and the pH is lower.
That is, it is understood that the amount of phosphoric acid used relative to the absorbed ammonia increases. This is because it is necessary to use a large amount of phosphoric acid in order to keep the pH of the absorbing solution low.
【0009】[0009]
【発明が解決しようとする課題】上述の如く、処理ガス
のアンモニア濃度を0にするためには、吸収液のpHを
4以下に設定する必要があるが、この場合、pHの設定
値を7にした時に比べて、同じ量のアンモニアを吸収す
るためのリン酸の使用量が約2.5倍となり、リン酸の
使用効率が低下する。また、このように低pHの吸収液
を用いることは、得られる液体肥料のpHが低くなり、
取り扱いに注意を要するものとなる。
As described above, in order to reduce the ammonia concentration of the processing gas to zero, it is necessary to set the pH of the absorbing solution to 4 or less. The amount of phosphoric acid used to absorb the same amount of ammonia is about 2.5 times that in the case of the above, and the use efficiency of phosphoric acid is reduced. In addition, the use of such a low-pH absorbent reduces the pH of the resulting liquid fertilizer,
It requires careful handling.
【0010】一方、吸収液のpHを7に設定すると、処
理ガス中に10ppm程度のアンモニアが残留し、十分
な処理を行えない。
On the other hand, when the pH of the absorbing solution is set to 7, about 10 ppm of ammonia remains in the processing gas, and sufficient processing cannot be performed.
【0011】本発明は上記従来の問題点を解決し、アン
モニア含有ガスをリン酸含有水溶液の吸収液と接触させ
ることにより、ガス中のアンモニアをリン酸アンモニウ
ムとして吸収させて除去する方法において、吸収液に吸
収されるアンモニア当たりのリン酸使用量を低減した上
で、アンモニアを高度に除去することができるアンモニ
ア含有ガスの処理方法を提供することを目的とする。
The present invention solves the above-mentioned conventional problems and provides a method for absorbing and removing ammonia in a gas as ammonium phosphate by bringing the ammonia-containing gas into contact with an absorbing solution of a phosphoric acid-containing aqueous solution. It is an object of the present invention to provide a method for treating an ammonia-containing gas, which is capable of highly removing ammonia while reducing the amount of phosphoric acid used per ammonia absorbed in the liquid.
【0012】[0012]
【課題を解決するための手段】本発明のアンモニア含有
ガスの処理方法は、アンモニアを含有する原ガスをリン
酸含有水溶液と接触させ、原ガス中のアンモニアをリン
酸含有水溶液に吸収させて除去するアンモニア含有ガス
の処理方法において、原ガスを第1吸収塔に導入して第
1のリン酸含有水溶液と接触させると共に、第1吸収塔
の処理ガスを第2吸収塔に導入し、第2のリン酸含有水
溶液と接触させる方法であって、第2のリン酸含有水溶
液のpHが第1のリン酸含有水溶液のpHよりも低いこ
とを特徴とする。
According to the method for treating an ammonia-containing gas of the present invention, an ammonia-containing raw gas is brought into contact with a phosphoric acid-containing aqueous solution, and the ammonia in the raw gas is absorbed by the phosphoric acid-containing aqueous solution and removed. In the method for treating an ammonia-containing gas described above, the raw gas is introduced into the first absorption tower and brought into contact with the first phosphoric acid-containing aqueous solution, and the processing gas from the first absorption tower is introduced into the second absorption tower. The method of contacting with a phosphoric acid-containing aqueous solution of the above, wherein the pH of the second phosphoric acid-containing aqueous solution is lower than the pH of the first phosphoric acid-containing aqueous solution.
【0013】本発明では、原ガスを、比較的pHの高い
リン酸含有水溶液を吸収液とする第1吸収塔と、比較的
pHの低いリン酸含有水溶液を吸収液とする第2吸収塔
とで2段処理し、第1吸収塔で原ガス中のアンモニアの
大部分を吸収除去し、第1吸収塔の処理ガス中に残留す
るアンモニアを第2吸収塔で除去する。
In the present invention, a first absorption tower using a phosphoric acid-containing aqueous solution having a relatively high pH as an absorbing solution, and a second absorption tower using a phosphoric acid-containing aqueous solution having a relatively low pH as an absorbing solution. The first absorption tower absorbs and removes most of the ammonia in the raw gas, and the ammonia remaining in the processing gas of the first absorption tower is removed by the second absorption tower.
【0014】このように、2段処理を行うことにより、
第2吸収塔の処理ガスのアンモニア濃度を0ppmにす
ることができ、しかも、単位アンモニア吸収量に対する
リン酸消費量を低減することができる。即ち、第1吸収
塔の吸収液は比較的高pHであるため、このpHを維持
するためのリン酸使用量は少量で良く、一方、第2吸収
塔の吸収液は比較的低pHではあるが、この第2吸収塔
では、第1吸収塔の処理ガス中に残留する少量のアンモ
ニアを吸収するのみであるため、この第2吸収塔の吸収
液のpHを維持するためのリン酸も少量で足りる。
As described above, by performing the two-stage processing,
The ammonia concentration of the processing gas in the second absorption tower can be reduced to 0 ppm, and the consumption of phosphoric acid per unit ammonia absorption can be reduced. That is, since the absorption liquid in the first absorption tower has a relatively high pH, the amount of phosphoric acid used to maintain this pH may be small, while the absorption liquid in the second absorption tower has a relatively low pH. However, since the second absorption tower only absorbs a small amount of ammonia remaining in the processing gas of the first absorption tower, a small amount of phosphoric acid for maintaining the pH of the absorbent in the second absorption tower is also small. Is enough.
【0015】本発明においては、第1のリン酸含有水溶
液を第1の吸収塔で循環させ、第2のリン酸含有水溶液
を第2の吸収塔で循環させ、第2のリン酸含有水溶液の
一部を連続的又は間欠的に第1のリン酸含有水溶液とし
て第1吸収塔に送給すると共に、第2吸収塔へリン酸を
補給し、第1吸収塔からアンモニアが吸収されたリン酸
アンモニウム含有水溶液の一部を排出することにより、
第1吸収塔からpH中性で取り扱い性に優れた液体肥料
を回収することができる。
In the present invention, the first aqueous solution containing phosphoric acid is circulated in the first absorption tower, and the second aqueous solution containing phosphoric acid is circulated in the second absorption tower. A portion is continuously or intermittently fed as a first phosphoric acid-containing aqueous solution to the first absorption tower, and phosphoric acid is supplied to the second absorption tower, and phosphoric acid in which ammonia is absorbed from the first absorption tower By discharging a part of the ammonium-containing aqueous solution,
A liquid fertilizer having a neutral pH and excellent handleability can be collected from the first absorption tower.
【0016】この場合、第1のリン酸含有水溶液のpH
が所定値を超えたときに、第2のリン酸含有水溶液の一
部を第1吸収塔に送給することで効率的な処理を行え
る。
In this case, the pH of the first aqueous solution containing phosphoric acid
When exceeds a predetermined value, efficient treatment can be performed by feeding a part of the second aqueous solution containing phosphoric acid to the first absorption tower.
【0017】[0017]
【発明の実施の形態】以下に図面を参照して本発明のア
ンモニア含有ガスの処理方法の実施の形態を詳細に説明
する。
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method for treating an ammonia-containing gas of the present invention will be described below in detail with reference to the drawings.
【0018】図1は、本発明の実施の形態を示す系統図
である。
FIG. 1 is a system diagram showing an embodiment of the present invention.
【0019】この方法では、吸収塔を2塔直列に設け、
原ガスを第1吸収塔1に導入してリン酸含有水溶液(以
下「第1の吸収液」と称す場合がある。)と向流接触さ
せた後、更に第2吸収塔2に導入してリン酸含有水溶液
(以下「第2の吸収液」と称す場合がある。)と向流接
触させ、第2吸収塔2の処理ガスを系外へ排出する。
In this method, two absorption towers are provided in series,
After the raw gas is introduced into the first absorption tower 1 and brought into countercurrent contact with a phosphoric acid-containing aqueous solution (hereinafter sometimes referred to as “first absorption liquid”), it is further introduced into the second absorption tower 2. It is brought into countercurrent contact with a phosphoric acid-containing aqueous solution (hereinafter sometimes referred to as “second absorption liquid”), and the processing gas in the second absorption tower 2 is discharged out of the system.
【0020】第1吸収塔1及び第2吸収塔2は、従来法
で用いられる吸収塔と同様の構成とされており、それぞ
れ塔内には充填材3,4が充填され、また塔下部には循
環槽5,6を備え、循環槽5,6内の吸収液をポンプP
,Pで塔上部の散水管7,8に循環するように構成
されている。
The first absorption tower 1 and the second absorption tower 2 have the same structure as the absorption tower used in the conventional method. Is provided with circulation tanks 5 and 6 and pumps the absorbent in circulation tanks 5 and 6 with pump P
1, and is configured to circulate the water spray pipe 7 and 8 of the tower top at P 2.
【0021】第1吸収塔1の循環槽(以下「第1循環
槽」と称す。)5には、液体肥料としてのリン酸アンモ
ニウム水溶液を抜き出すための配管20が設けられてい
る。一方、第2吸収塔2の循環槽(以下「第2循環槽」
と称す。)6にはリン酸水溶液の供給配管21が設けら
れると共に、この第2循環槽6の吸収液を第1吸収塔1
の第1循環槽5に送給する配管22が設けられている。
The circulation tank (hereinafter referred to as "first circulation tank") 5 of the first absorption tower 1 is provided with a pipe 20 for extracting an aqueous solution of ammonium phosphate as a liquid fertilizer. On the other hand, the circulation tank of the second absorption tower 2 (hereinafter, “second circulation tank”)
Called. ) 6 is provided with a supply pipe 21 of a phosphoric acid aqueous solution, and the absorbent in the second circulation tank 6 is supplied to the first absorption tower 1.
A pipe 22 for feeding the first circulation tank 5 is provided.
【0022】原ガスは、配管23より第1吸収塔1の下
部に導入され、塔内を上昇する過程で、循環ポンプP
を備える配管24で第1循環槽5から循環され、散水管
7から散水されるリン酸含有水溶液(第1の吸収液)と
向流接触する。第1の吸収液と接触してアンモニアが吸
収除去された処理ガスは配管25から第2吸収塔2の塔
下部に送給される。
The raw gas is introduced into the lower part of the first absorption tower 1 through a pipe 23, and in the process of ascending in the tower, the circulation pump P 1
Is circulated from the first circulating tank 5 by the pipe 24 provided with the water, and comes into countercurrent contact with the phosphoric acid-containing aqueous solution (first absorbing liquid) sprinkled from the water sprinkling pipe 7. The processing gas from which the ammonia has been absorbed and removed by contact with the first absorption liquid is supplied from the pipe 25 to the lower part of the second absorption tower 2.
【0023】第2吸収塔2に導入された第1吸収塔1の
処理ガスは、塔内を上昇する過程で、循環ポンプP
備える配管26で第2循環槽6から循環され、散水管8
から散水されるリン酸含有水溶液(第2の吸収液)と向
流接触する。第2の吸収液と接触してアンモニアが吸収
除去された処理ガスは配管27より系外へ排出される。
The first processing gas of the absorption tower 1 is introduced into the second absorption tower 2, in the course of rising in the column is circulated from the second circulation tank 6 by a pipe 26 provided with a circulating pump P 2, sprinkling pipe 8
And a phosphoric acid-containing aqueous solution (second absorbing solution) sprinkled from the surface. The processing gas from which the ammonia has been absorbed and removed by contact with the second absorbing liquid is discharged from the pipe 27 to the outside of the system.
【0024】第1吸収塔1及び第2吸収塔2では、原ガ
スの処理により、アンモニアの吸収でpHが上昇する。
In the first absorption tower 1 and the second absorption tower 2, due to the treatment of the raw gas, the pH increases due to the absorption of ammonia.
【0025】本実施の形態では、第1の吸収液のpHが
上昇した場合には、第2吸収塔2の第2の吸収液を配管
22で第1循環槽5に送給して第1の吸収液のpHを下
げる。また、第2循環槽6には、この第1吸収塔1への
移送量と同量のリン酸水溶液を配管21より補給してp
Hを下げる。
In the present embodiment, when the pH of the first absorbing solution rises, the second absorbing solution in the second absorbing tower 2 is supplied to the first circulating tank 5 through the pipe 22 and the first absorbing solution is supplied to the first circulating tank 5. Lower the pH of the absorbing solution. Further, the same amount of phosphoric acid aqueous solution as the transfer amount to the first absorption tower 1 is supplied from the pipe 21 to the second circulation tank 6, and p
Lower H.
【0026】液体肥料としてのリン酸アンモニウム水溶
液は、第1循環槽5から配管20より抜き出す。この抜
き出し量は、第1循環槽5に設置したレベル計によって
制御する。この抜き出し量は、循環槽保有液量の数十分
の一となるため、抜き出しと移送とが干渉して問題とな
ることはない。
An aqueous solution of ammonium phosphate as a liquid fertilizer is extracted from the first circulation tank 5 through a pipe 20. This withdrawal amount is controlled by a level meter installed in the first circulation tank 5. Since the withdrawal amount is several tenths of the amount of the liquid held in the circulation tank, there is no problem in that the withdrawal and the transfer interfere with each other.
【0027】本発明においては、第1の吸収液のpHは
6.8〜7.2、特にpH7程度(リン酸濃度8〜10
重量%程度)に維持するのが好ましく、このために、第
1の吸収液のpHが設定pH値を超えた場合には第2の
吸収液を第1吸収塔1に移送し、第1の吸収液のpHが
設定pH値にまで低下したところで、この第2の吸収液
の移送を停止するようにするのが好ましい。
In the present invention, the pH of the first absorbing solution is 6.8 to 7.2, particularly about pH 7 (phosphoric acid concentration 8 to 10).
(% By weight). For this reason, when the pH of the first absorbing solution exceeds a set pH value, the second absorbing solution is transferred to the first absorption tower 1 and the first absorbing solution is transferred to the first absorbing tower 1. When the pH of the absorbing solution has dropped to the set pH value, it is preferable to stop the transfer of the second absorbing solution.
【0028】また、第2の吸収液のpHは4以下、特に
pH3.0〜4.0程度(リン酸濃度8〜10重量%程
度)に維持するのが好ましく、このpH値に維持するこ
とができるように、第2の吸収液の第1吸収塔1への移
送時に、所定濃度のリン酸水溶液を第2吸収塔2に補給
する。なお、第2吸収塔2では、アンモニア吸収量が少
なく、従って、第2の吸収液のpHは、補給するリン酸
水溶液のpHより若干高くなる程度であり、特にリン酸
水溶液の補給量を制御することなく、上記移送量と同量
のリン酸水溶液を補給するのみで、pHを維持すること
が可能である。
It is preferable that the pH of the second absorbing solution is maintained at 4 or less, particularly at a pH of about 3.0 to 4.0 (phosphoric acid concentration of about 8 to 10% by weight). During the transfer of the second absorbing liquid to the first absorption tower 1, a predetermined concentration of a phosphoric acid aqueous solution is supplied to the second absorption tower 2 so that the second absorption liquid can be transported. In the second absorption tower 2, the ammonia absorption amount is small, and therefore, the pH of the second absorption liquid is slightly higher than the pH of the phosphoric acid aqueous solution to be replenished. The pH can be maintained only by replenishing the same amount of the phosphoric acid aqueous solution as the transfer amount without performing the above.
【0029】第1吸収塔1及び第2吸収塔2のガス流速
や接触時間、液ガス比等には特に制限はないが、通常の
場合、第1吸収塔1,第2吸収塔2共に、ガス流速0.
5〜0.7m/秒、接触時間2.0〜3.0秒、液ガス
比4.0〜6.0L/Nmで運転を行って、第1吸収
塔1において、原ガス中のアンモニアの95〜97%を
吸収除去し、第2吸収塔2において、第1吸収塔1の処
理ガス中に残留するアンモニアを完全に除去するように
するのが好ましい。
The gas flow rate, the contact time, the liquid-gas ratio, and the like of the first absorption tower 1 and the second absorption tower 2 are not particularly limited, but usually, both the first absorption tower 1 and the second absorption tower 2 Gas flow rate 0.
5~0.7M / sec, contact time 2.0 to 3.0 seconds, performing the operation with liquid-to-gas ratio 4.0~6.0L / Nm 3, in the first absorption tower 1, ammonia raw gas It is preferable to absorb and remove 95 to 97% of the ammonia in the second absorption tower 2 to completely remove ammonia remaining in the processing gas of the first absorption tower 1.
【0030】[0030]
【実施例】以下に実施例及び比較例を挙げて本発明をよ
り具体的に説明する。
The present invention will be described more specifically below with reference to examples and comparative examples.
【0031】実施例1 図1に示す方法により、下水汚泥のコンポスト化設備か
ら排出されるアンモニア含有排ガス(アンモニア濃度:
200〜300ppm)の処理を行った。第1吸収塔1
及び第2吸収塔2の処理条件は、いずれも下記の通りと
した。 [処理条件] ガス流速 :0.6m/秒 接触時間 :2.5秒 充填層高さ:1.5m 液ガス比 :5L/Nm
Example 1 An ammonia-containing exhaust gas discharged from a sewage sludge composting facility (ammonia concentration:
(200 to 300 ppm). First absorption tower 1
The treatment conditions for the second absorption tower 2 were as follows. [Treatment conditions] Gas flow rate: 0.6 m / sec Contact time: 2.5 sec Packed bed height: 1.5 m Liquid / gas ratio: 5 L / Nm 3
【0032】従って、2塔合計での接触時間は5秒で充
填層高さは3m、液ガス比は10L/Nmになる。
Accordingly, the contact time of the two towers in total is 5 seconds, the height of the packed bed is 3 m, and the liquid-gas ratio is 10 L / Nm 3 .
【0033】第1吸収塔1の吸収液のpHが7.2に上
昇したときに、第2吸収塔2の吸収液の一部を第1循環
槽5に移送し、この移送により第1吸収塔1の吸収液の
pHが7.0になると移送を停止した。また、第2循環
槽6には第1吸収塔1に移送した量と同量のリン酸水溶
液(pH0.4、濃度9重量%)を補給した。
When the pH of the absorption liquid in the first absorption tower 1 rises to 7.2, a part of the absorption liquid in the second absorption tower 2 is transferred to the first circulation tank 5, and the first absorption is performed by this transfer. When the pH of the absorption solution in the tower 1 reached 7.0, the transfer was stopped. Further, the same amount of phosphoric acid aqueous solution (pH 0.4, concentration 9% by weight) as the amount transferred to the first absorption tower 1 was supplied to the second circulation tank 6.
【0034】これにより第1吸収塔1の吸収液のpHを
約7に維持すると共に、第2吸収塔2の吸収液のpHを
約3に維持した。
Thus, the pH of the absorbing solution in the first absorption tower 1 was maintained at about 7, and the pH of the absorbing solution in the second absorption tower 2 was maintained at about 3.
【0035】その結果、第1吸収塔1から排出される処
理ガスのアンモニア濃度は10〜15ppmで、原ガス
中のアンモニアの95%が第1吸収塔1で除去された。
また、第2吸収塔2の処理ガスのアンモニア濃度は0p
pmであり、アンモニアを完全に除去することができ
た。
As a result, the ammonia concentration of the processing gas discharged from the first absorption tower 1 was 10 to 15 ppm, and 95% of the ammonia in the raw gas was removed in the first absorption tower 1.
The ammonia concentration of the processing gas in the second absorption tower 2 is 0 p
pm, and ammonia could be completely removed.
【0036】この処理において、第1循環槽5から引き
抜いたリン酸アンモニウム水溶液のP/N比は1.2
5、pHは約7で吸収したアンモニアに対するリン酸消
費量(系外へ抜き出されるリン酸量)が少なく、また、
pH中性で液体肥料としての取り扱い性に優れるもので
あった。
In this treatment, the P / N ratio of the aqueous ammonium phosphate solution withdrawn from the first circulation tank 5 was 1.2.
5. The consumption of phosphoric acid with respect to the ammonia absorbed at about pH 7 (the amount of phosphoric acid extracted to the outside of the system) is small.
It was pH-neutral and excellent in handling properties as a liquid fertilizer.
【0037】比較例1,2 図2に示す従来法により、実施例1と同様の原ガスの処
理を行った。
Comparative Examples 1 and 2 The same raw gas treatment as in Example 1 was performed by the conventional method shown in FIG.
【0038】この比較例では、実施例1と条件をそろえ
るために、ガス流速0.6m/秒で接触時間5秒、液ガ
ス比が10L/Nmとなるように吸収塔を設計し、ま
た充填層高さは3mとした。
In this comparative example, the absorption tower was designed so that the gas flow rate was 0.6 m / sec, the contact time was 5 seconds, and the liquid-gas ratio was 10 L / Nm 3 in order to match the conditions of Example 1. The height of the packed bed was 3 m.
【0039】その結果、吸収液のリン酸含有水溶液のp
Hを4とした場合(比較例1)には、実施例1と同様に
処理ガスのアンモニア濃度を0ppmにすることができ
たが、液体肥料として抜き出したリン酸アンモニウム水
溶液のP/N比は3.33でリン酸消費量が多く、ま
た、この液は低pHであるために取り扱い性に注意を要
するものであった。
As a result, p of the phosphoric acid-containing aqueous solution
When H was set to 4 (Comparative Example 1), the ammonia concentration of the processing gas could be reduced to 0 ppm as in Example 1, but the P / N ratio of the ammonium phosphate aqueous solution extracted as a liquid fertilizer was: At 3.33, the consumption of phosphoric acid was large, and since this solution had a low pH, care was required in handling.
【0040】一方、吸収液のリン酸含有水溶液のpHを
7とした場合には、P/N比1.25のリン酸アンモニ
ウム水溶液が得られ、リン酸の消費量は実施例1と同様
に少なく、pHも中性であることから液体肥料としても
好適であったが、処理ガスのアンモニア濃度は10pp
mであり、アンモニアが残留した。
On the other hand, when the pH of the aqueous solution containing phosphoric acid in the absorbing solution was set to 7, an aqueous solution of ammonium phosphate having a P / N ratio of 1.25 was obtained, and the consumption of phosphoric acid was the same as in Example 1. It was suitable as a liquid fertilizer because of its low pH and neutral pH, but the ammonia concentration of the treated gas was 10 pp
m and ammonia remained.
【0041】上記実施例及び比較例の結果を表2にまと
めて示す。
Table 2 summarizes the results of the above Examples and Comparative Examples.
【0042】[0042]
【表2】 [Table 2]
【0043】[0043]
【発明の効果】以上詳述した通り、本発明のアンモニア
含有ガスの処理方法によれば、アンモニアを含有する原
ガスをリン酸含有水溶液と接触させて、原ガス中のアン
モニアをリン酸含有水溶液に吸収させて除去するに当た
り、リン酸使用量を低減した上で、アンモニア除去効率
を高め、アンモニアを含まない処理ガスを得ることがで
きる。しかも、液体肥料としての商品価値の高いpH中
性のリン酸アンモニウム水溶液を回収することができ
る。
As described above in detail, according to the method for treating an ammonia-containing gas of the present invention, the raw gas containing ammonia is brought into contact with the aqueous solution containing phosphoric acid, and the ammonia in the raw gas is converted into the aqueous solution containing phosphoric acid. In removing and removing the gas, the amount of phosphoric acid used is reduced, and the ammonia removal efficiency is increased, so that a process gas containing no ammonia can be obtained. In addition, a pH neutral ammonium phosphate aqueous solution having high commercial value as a liquid fertilizer can be recovered.
【図面の簡単な説明】[Brief description of the drawings]
【図1】本発明のアンモニア含有ガスの処理方法の実施
の形態を示す系統図である。
FIG. 1 is a system diagram showing an embodiment of a method for treating an ammonia-containing gas of the present invention.
【図2】従来のアンモニア含有ガスの処理方法を示す系
統図である。
FIG. 2 is a system diagram showing a conventional method for treating an ammonia-containing gas.
【符号の説明】[Explanation of symbols]
1 第1吸収塔 2 第2吸収塔 3,4 充填材 5 第1循環槽 6 第2循環槽 7,8 散水管 DESCRIPTION OF SYMBOLS 1 1st absorption tower 2 2nd absorption tower 3,4 Filler 5 1st circulation tank 6 2nd circulation tank 7,8 Sprinkling pipe
───────────────────────────────────────────────────── フロントページの続き (72)発明者 布施 智之 東京都新宿区西新宿三丁目4番7号 栗田 工業株式会社内 (72)発明者 丸山 克也 東京都新宿区西新宿三丁目4番7号 栗田 工業株式会社内 Fターム(参考) 4D002 AA13 AC10 BA02 CA07 CA13 DA18 EA02 EA13 EA20 FA06 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Tomoyuki Fuse, Inventor 3- 4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Kurita Industry Co., Ltd. (72) Katsuya Maruyama 3-4-2, Nishi-Shinjuku, Shinjuku-ku, Tokyo Kurita Kogyo Co., Ltd. F term (reference) 4D002 AA13 AC10 BA02 CA07 CA13 DA18 EA02 EA13 EA20 FA06

Claims (3)

    【特許請求の範囲】[Claims]
  1. 【請求項1】 アンモニアを含有する原ガスをリン酸含
    有水溶液と接触させ、原ガス中のアンモニアをリン酸含
    有水溶液に吸収させて除去するアンモニア含有ガスの処
    理方法において、 原ガスを第1吸収塔に導入して第1のリン酸含有水溶液
    と接触させると共に、第1吸収塔の処理ガスを第2吸収
    塔に導入し、第2のリン酸含有水溶液と接触させる方法
    であって、 第2のリン酸含有水溶液のpHが第1のリン酸含有水溶
    液のpHよりも低いことを特徴とするアンモニア含有ガ
    スの処理方法。
    1. A method for treating an ammonia-containing gas in which a raw gas containing ammonia is brought into contact with a phosphoric acid-containing aqueous solution and the ammonia in the raw gas is absorbed by the phosphoric acid-containing aqueous solution and removed therefrom, wherein the raw gas is first absorbed A method of introducing the first phosphoric acid-containing aqueous solution into the column and bringing it into contact with the first phosphoric acid-containing aqueous solution, introducing the processing gas of the first absorption tower into the second absorption tower, and bringing the processing gas into contact with the second phosphoric acid-containing aqueous solution; Wherein the pH of the aqueous phosphoric acid-containing solution is lower than the pH of the first aqueous phosphoric acid-containing solution.
  2. 【請求項2】 請求項1において、第1のリン酸含有水
    溶液を第1の吸収塔で循環させ、第2のリン酸含有水溶
    液を第2の吸収塔で循環させる方法であって、 第2のリン酸含有水溶液の一部を第1のリン酸含有水溶
    液として第1吸収塔に送給すると共に、第2吸収塔へリ
    ン酸を補給し、第1吸収塔からアンモニアが吸収された
    リン酸アンモニウム含有水溶液の一部を排出することを
    特徴とするアンモニア含有ガスの処理方法。
    2. The method according to claim 1, wherein the first phosphoric acid-containing aqueous solution is circulated in the first absorption tower, and the second phosphoric acid-containing aqueous solution is circulated in the second absorption tower. A part of the phosphoric acid-containing aqueous solution is supplied as a first phosphoric acid-containing aqueous solution to the first absorption tower, and phosphoric acid is supplied to the second absorption tower, and the phosphoric acid in which ammonia is absorbed from the first absorption tower A method for treating an ammonia-containing gas, comprising discharging a part of an ammonium-containing aqueous solution.
  3. 【請求項3】 請求項2において、第1のリン酸含有水
    溶液のpHが所定値を超えたときに、第2のリン酸含有
    水溶液の一部を第1吸収塔に送給することを特徴とする
    アンモニア含有ガスの処理方法。
    3. The method according to claim 2, wherein when the pH of the first phosphoric acid-containing aqueous solution exceeds a predetermined value, a part of the second phosphoric acid-containing aqueous solution is sent to the first absorption tower. For treating ammonia-containing gas.
JP2000343863A 2000-11-10 2000-11-10 Method for treating ammonia gas Pending JP2002143639A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004011127A1 (en) * 2002-07-30 2004-02-05 Scan-Airclean Aps Method of purifying air, process for manufacture of fertilizer, apparatus for purifying air and building provided with this apparatus
CN102527212A (en) * 2011-12-07 2012-07-04 南京钢铁股份有限公司 Comprehensive treating method and system for tail gas in ammoniac tank of coke-oven plant
CN103446865A (en) * 2013-07-03 2013-12-18 四川大学 Nitrophosphate tail gas deamination device and nitrophosphate tail gas deamination process
CN103894048A (en) * 2014-04-18 2014-07-02 中石化南京工程有限公司 Method for treating low-concentration ammonia-containing tail gas
CN104474866A (en) * 2014-11-25 2015-04-01 安徽省鸿福新型建材科技有限公司 Environment protection device used for managing kiln flue gas

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004011127A1 (en) * 2002-07-30 2004-02-05 Scan-Airclean Aps Method of purifying air, process for manufacture of fertilizer, apparatus for purifying air and building provided with this apparatus
CN102527212A (en) * 2011-12-07 2012-07-04 南京钢铁股份有限公司 Comprehensive treating method and system for tail gas in ammoniac tank of coke-oven plant
CN102527212B (en) * 2011-12-07 2013-08-28 南京钢铁股份有限公司 Comprehensive treating method and system for tail gas in ammoniac tank of coke-oven plant
CN103446865A (en) * 2013-07-03 2013-12-18 四川大学 Nitrophosphate tail gas deamination device and nitrophosphate tail gas deamination process
CN103894048A (en) * 2014-04-18 2014-07-02 中石化南京工程有限公司 Method for treating low-concentration ammonia-containing tail gas
CN104474866A (en) * 2014-11-25 2015-04-01 安徽省鸿福新型建材科技有限公司 Environment protection device used for managing kiln flue gas

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