JP3755259B2 - Wastewater treatment method in coke production facility - Google Patents
Wastewater treatment method in coke production facility Download PDFInfo
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- JP3755259B2 JP3755259B2 JP29687197A JP29687197A JP3755259B2 JP 3755259 B2 JP3755259 B2 JP 3755259B2 JP 29687197 A JP29687197 A JP 29687197A JP 29687197 A JP29687197 A JP 29687197A JP 3755259 B2 JP3755259 B2 JP 3755259B2
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- ammonia
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- 238000004065 wastewater treatment Methods 0.000 title claims description 30
- 239000000571 coke Substances 0.000 title claims description 18
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 127
- 229910021529 ammonia Inorganic materials 0.000 claims description 63
- 239000007788 liquid Substances 0.000 claims description 45
- 239000002351 wastewater Substances 0.000 claims description 45
- 238000000034 method Methods 0.000 claims description 20
- 239000010802 sludge Substances 0.000 claims description 9
- 238000011282 treatment Methods 0.000 claims description 6
- 239000007789 gas Substances 0.000 description 47
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 230000001105 regulatory effect Effects 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 241000894006 Bacteria Species 0.000 description 4
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000005416 organic matter Substances 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 230000001546 nitrifying effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
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- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
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- Physical Water Treatments (AREA)
- Degasification And Air Bubble Elimination (AREA)
- Activated Sludge Processes (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明はコークス製造設備における廃水の処理方法に関するものであり、特に廃水中のアンモニア分の除去方法に関するものである。
【０００２】
【従来の技術】
コークス製造設備では各種の廃水が発生する。この第一は余剰ガス液である。コークス製造では、コークス炉から流出する高温のコークス炉ガスに水を噴射してガスを冷却し、含まれているタール分を凝縮させる。次いでコークス炉ガスは間接冷却により更に冷却し、ガス精製装置に送られる。これらのガス冷却工程では水を回収し、含まれているタール分をデカンターなどで除去したのち、コークス炉ガスへの噴射に循環再利用している。この水はガス液と称されており、コークス炉ガス中のアンモニアを吸収して数千ｐｐｍのアンモニア分を含んでいる。このアンモニア分の一部は酸と塩を形成した固定アンモニアとして、他は遊離アンモニアとして存在している。またコークス炉から流出するコークス炉ガス中には、石炭付着水や乾留過程で石炭から生成した水が水蒸気として含まれている。従ってガス液の量は、放置しておくと、この水蒸気から生成する水量だけ漸増するので、ガス液の循環系からその一部を抜出して、循環系の液量が所定の範囲に収まるようにしている。この抜出されたガス液が余剰ガス液であり、前述の如く数千ｐｐｍのアンモニア分を含んでおり、かつ有機物で高度に汚染されているので、活性汚泥処理を経た後でなければ、公共水域に排出することはできない。
コークス製造設備では、余剰ガス液以外にも、コークス炉ガスの精製工程やタールの処理工程などからも種々の廃水が排出される。これらの種々の排出源からの廃水も、相当量のアンモニア分と有機物を含んでいるものが多く、それらは余剰ガス液と同様に、活性汚泥処理を経た後でなければ、公共水域に排出することはできない。
【０００３】
【発明が解決しようとする課題】
公共水域に排出する廃水のアンモニア分の濃度は厳しく規制されている。従ってコークス製造設備の廃水のように高濃度のアンモニア分を含むものの処理においては、公共水域へ排出する際のアンモニア分の濃度を如何にして規制値以下にするかが、廃水処理費用に大きく影響する。すなわち廃水の発生量及びそのアンモニア分の含有量は常に変動するので、仮にこのような変動が生じても規制値を遵守し得るように常に余裕をもってアンモニア分の除去を行うと、当然のことながら処理費用が増大する。逆に平均的な廃水の発生量及びそのアンモニア分の含有量を基準にして処理を行う方法は、処理費用が安くて済むが、大容量の貯槽を設置して発生源での変動を平均化するなど、変動を吸収し得る手段を用意しておかなければ、規制値を遵守することはできない。本発明は廃水処理費用を低く維持しつつ、規制値を遵守することのできる方法を提供せんとするものである。
【０００４】
【課題を解決するための手段】
本発明によれば、ガス液循環系から排出される余剰ガス液を、他の排出源からの汚染された廃水と一緒にして、活性汚泥法を含む廃水処理系で処理するコークス製造設備における廃水の処理方法において、廃水処理系に流入する全廃水のアンモニア分が所定の範囲になるように、少くとも余剰ガス液をスチームストリッピングに供してそのアンモニア分を低減させてから廃水処理系に流入させること、及びスチームストリッピングにおけるアンモニアの除去量を廃水の持込むアンモニア分の量に応じて調節し、余剰ガス液の一部はスチームストリッピングに供したのち廃水処理系に流入させ、残部はスチームストリッピングに供することなく廃水処理系に流入させ、かつ両者の比率を調節することにより廃水処理系に持込まれるアンモニア分を調節することにより、廃水処理費用を低減させることができる。
【０００５】
【発明の実施の形態】
本発明では、廃水から予じめスチームストリッピングによりアンモニア分を除去しておくことにより、廃水処理系に流入する廃水のアンモニア分が所定の範囲に収まるようにする。前述のようにコークス製造設備では排出源を異にする種々の廃水が廃水処理系に流入するが、廃水の全アンモニア分の相当部分、通常は５０％以上、は余剰ガス液のアンモニア分である。余剰ガス液は、大量に循環しているガス液の一部を抜出したものであり、その量及びアンモニア分の変動は比較的緩慢である。本発明ではこの余剰ガス液をスチームストリッピングに供する。通常は余剰ガス液だけをスチームストリッピングに供するが、所望ならば余剰ガス液に加えて他の排出源からの廃水もスチームストリッピングに供してもよい。スチームストリッピングにおいて廃水から除去するアンモニア分の量は、廃水処理系に流入する廃水のアンモニア分が所定の範囲内になるように決定する。スチームストリッピングでは、供給する廃水及びスチーム量を調節することにより、アンモニア分の除去量を殆ど時間遅れなく且つ任意に制御することができる。従って廃水が持込むアンモニア分の変動に直ちに対応することができる。
【０００６】
スチームストリッピングによるアンモニア除去量の制御は、いくつかの方法で行うことができる。例えば余剰ガス液の全量を常にスチームストリッピングに供給しておき、スチーム量を制御することによりアンモニア分の除去量を制御することができる。しかし通常は、スチームストリッピングに供給する余剰ガス液量を制御することにより、アンモニア分の除去量を制御するのが好ましい。図１は、このような方式を実施する場合の液の流れの１例を示すもので、余剰ガス液は導管１を経て供給され、その一部はストリッピング塔２を経て、残部は直接に、廃水貯槽３に流入する。ストリッピング塔２には導管４を経てスチームが供給され、余剰ガス液中のアンモニア分はスチームと一緒に塔頂から導管５を経て流出する。このアンモニアはコークス炉ガスの脱アンモニア系に導入するなど、適宜の方法で処理される。廃水貯槽３には、導管６を経て他の排出源からの廃水も流入している。廃水貯槽３からは導管７を経て廃水が一定速度で流出し、活性汚泥法を含む廃水処理系に流入する。図１において、導管７を流れる廃水のアンモニア分の濃度を窒素計で測定し、余剰ガス液のアンモニア分を、窒素計と流量計で測定する。この測定値に基いてストリッピング塔２で除去すべきアンモニア分の量を算出し、ストリッピング塔でのアンモニア分の除去率に基いて、ストリッピング塔に供給する余剰ガス液量を算出する。またストリッピング塔から流出する余剰ガス液中のアンモニア分を測定し、除去率が所定の値となるように供給するスチーム量を調節する。
【０００７】
廃水貯槽３から流出する廃水を受入れる廃水処理系は、活性汚泥法を主体とし、これに更に所望により他の処理を組合せたものである。最も簡単には、活性汚泥法によりＢＯＤを低減させたのち、浮遊物（ＳＳ）を濾過ないしは沈降により除去して公共水域に排出する。所望ならば活性汚泥法と硝化菌、脱窒菌による硝化・脱窒とを組合せ、廃水中のアンモニア分を更に低減させることもできる。
【０００８】
本発明によれば、廃水処理系に流入する廃水のアンモニア分を平均化させるための大きな廃水貯槽を設置する必要がない。また余剰ガス液には微生物の生育に有害なシアンが含まれているが、このシアンにより後続する廃水処理系が悪影響を受けるのを回避できる。例えば、硝化菌や脱窒菌はシアンの影響を受け易く、シアン濃度が脱窒槽で約３０ｐｐｍ以上になると生育が著しく阻害されるとされている。また活性汚泥もシアンの影響を受け、シアン濃度が曝気槽で約５０ｐｐｍ以上になると生育が阻害されるようになる。しかし本発明によれば、スチームストリッピングによりアンモニアを除去すると、余剰ガス液中のシアンも容易に留去されるので、後続する廃水処理系が余剰ガス液中のシアンにより阻害されるのを回避することができる。更に本発明では、廃水処理系に流入するアンモニア分が所定の値となるように、廃水から除去すべきアンモニア分の量に応じて、必要最小限のスチームストリッピングを行えばよいので、スチーム量を大幅に節減できる。例えば平均して、余剰ガス液が遊離アンモニアを１９５ｋｇ／ｈｒ、固定アンモニアを１０５ｋｇ／ｈｒで廃水処理系に持込んでおり、他の排出源からの廃水が１００ｋｇ／ｈｒのアンモニア分を廃水処理系に持込んでいるが、公共水域へ排出する廃水中のアンモニア分の規制により、後続する廃水処理系には３００ｋｇ／ｈｒのアンモニア分しか流入させられない場合を想定する。廃水の量とそのアンモニア濃度が常に一定ならば、スチームストリッピングにより余剰ガス液の遊離アンモニアのうち１００ｋｇ／ｈｒを除去すればよい。スチームストリッピングによる遊離アンモニアの除去率を９０％とすると、余剰ガス液の約５７％をスチームストリッピングに供すればよい。しかし若し他の排出源からの排水の持込むアンモニア分が最大で１５０ｋｇ／ｈｒに達するとすると、この場合においても後続する廃水処理系に３００ｋｇ／ｈｒのアンモニア分しか流入させない為には、余剰ガス液の遊離アンモニアのうちの１５０ｋｇ／ｈｒを除去しなければならない。そのためには余剰ガス液の約８６％をスチームストリッピングに供しなければならず、スチームストリッピングに供する余剰ガス液は約５０％増加する。スチームストリッピングに供する液量とスチーム消費量とはほぼ比例するので、スチームの消費量も約５０％増加することになる。この想定事例からも明らかなように、廃水の持込むアンモニア分が変動しても大丈夫なように常に余裕をもってスチームストリッピングを行うと、廃水の持込むアンモニア量に応じてスチームストリッピングでのアンモニア除去量を調節する場合に比し、スチーム消費量が著しく増加する。かつ、後続する廃水処理系の活性汚泥も、アンモニア分の濃度が変動するので管理が面倒である。
【図面の簡単な説明】
【図１】本発明方法により余剰ガス液のスチームストリッピングを行う場合の液の流れの１例を示すものである。
【符号の説明】
１ 余剰ガス液の供給導管
２ ストリッピング塔
３ 廃水貯槽
４ スチーム供給導管
５ アンモニアガス流出管
６ 他の排出源からの廃水の供給導管
７ 廃水の流出管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating wastewater in a coke production facility, and more particularly to a method for removing ammonia in wastewater.
[0002]
[Prior art]
Various types of wastewater are generated at coke production facilities. The first is a surplus gas liquid. In coke production, water is injected into the high-temperature coke oven gas flowing out of the coke oven to cool the gas and condense the tar content. The coke oven gas is then further cooled by indirect cooling and sent to a gas purification unit. In these gas cooling processes, water is collected and the tar content is removed with a decanter, etc., and then recycled for injection into coke oven gas. This water is called a gas liquid and absorbs ammonia in the coke oven gas and contains several thousand ppm of ammonia. A part of this ammonia is present as fixed ammonia which forms a salt with an acid, and the other as free ammonia. The coke oven gas flowing out of the coke oven contains coal adhering water and water produced from coal during the dry distillation process as water vapor. Therefore, the amount of the gas liquid gradually increases by the amount of water generated from this water vapor, so that a part of the gas liquid is extracted from the gas liquid circulation system so that the amount of the circulation system liquid falls within a predetermined range. ing. This extracted gas liquid is a surplus gas liquid that contains several thousand ppm of ammonia as described above, and is highly contaminated with organic matter. It cannot be discharged into the water area.
In the coke production facility, various waste water is discharged from the coke oven gas refining process and tar processing process in addition to the surplus gas liquid. Many wastewater from these various sources also contain substantial amounts of ammonia and organic matter, and, like surplus gas liquids, they are discharged into public waters unless they have been subjected to activated sludge treatment. It is not possible.
[0003]
[Problems to be solved by the invention]
The concentration of ammonia in wastewater discharged into public water areas is strictly regulated. Therefore, in the treatment of wastewater containing high concentrations of ammonia such as wastewater from coke production facilities, how to reduce the concentration of ammonia when discharged into public water areas is below the regulated value has a significant impact on wastewater treatment costs. To do. In other words, since the amount of wastewater generated and the content of its ammonia always fluctuate, it is a matter of course that if the ammonia content is always removed with a margin so that the regulatory values can be observed even if such fluctuations occur. Processing costs increase. On the other hand, the treatment method based on the average amount of wastewater generated and its ammonia content is low in processing costs, but a large-capacity storage tank is installed to average fluctuations at the source. If you do not prepare a means that can absorb fluctuations, such as doing this, you will not be able to comply with regulatory values. The present invention seeks to provide a method that allows compliance with regulatory values while keeping wastewater treatment costs low.
[0004]
[Means for Solving the Problems]
According to the present invention, waste gas in a coke production facility for treating surplus gas liquid discharged from the gas liquid circulation system together with contaminated waste water from other discharge sources in a waste water treatment system including an activated sludge process. In this treatment method, at least the surplus gas liquid is subjected to steam stripping to reduce the ammonia content so that the ammonia content of the total wastewater flowing into the wastewater treatment system falls within the predetermined range, and then flows into the wastewater treatment system. And adjusting the amount of ammonia removed in the steam stripping according to the amount of ammonia contained in the wastewater, a part of the surplus gas liquid is supplied to the wastewater treatment system after being subjected to steam stripping, and the remainder is The ammonia content brought into the wastewater treatment system by allowing it to flow into the wastewater treatment system without being subjected to steam stripping and adjusting the ratio between the two. By adjusting, it is possible to reduce the wastewater treatment costs.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the ammonia content is removed from the wastewater by steam stripping in advance, so that the ammonia content of the wastewater flowing into the wastewater treatment system falls within a predetermined range. As described above, in the coke production facility, various wastewaters with different emission sources flow into the wastewater treatment system, but a substantial part of the total ammonia in the wastewater, usually 50% or more, is the ammonia content of the surplus gas liquid. . The surplus gas liquid is obtained by extracting a part of the gas liquid circulating in a large amount, and the fluctuation of the amount and the ammonia content is relatively slow. In the present invention, this surplus gas liquid is subjected to steam stripping. Normally, only the surplus gas liquid is subjected to steam stripping, but if desired, waste water from other discharge sources may be subjected to steam stripping in addition to the surplus gas liquid. The amount of ammonia removed from the wastewater in the steam stripping is determined so that the ammonia content of the wastewater flowing into the wastewater treatment system falls within a predetermined range. In the steam stripping, the removal amount of ammonia can be arbitrarily controlled with little time delay by adjusting the amount of waste water to be supplied and the amount of steam. Therefore, it is possible to immediately cope with fluctuations in the ammonia content brought into the wastewater.
[0006]
The amount of ammonia removed by steam stripping can be controlled by several methods. For example, the removal amount of ammonia can be controlled by always supplying the entire amount of surplus gas liquid to steam stripping and controlling the steam amount. However, usually, it is preferable to control the removal amount of ammonia by controlling the amount of surplus gas liquid supplied for steam stripping. FIG. 1 shows an example of the flow of liquid when such a method is carried out. The surplus gas liquid is supplied through a conduit 1, part of which is passed through a
[0007]
The wastewater treatment system for receiving wastewater flowing out from the
[0008]
According to the present invention, there is no need to install a large wastewater storage tank for averaging the ammonia content of wastewater flowing into the wastewater treatment system. The surplus gas liquid contains cyan which is harmful to the growth of microorganisms, and it can be avoided that the subsequent waste water treatment system is adversely affected by this cyan. For example, nitrifying bacteria and denitrifying bacteria are easily affected by cyanide, and growth is markedly inhibited when the cyan concentration is about 30 ppm or more in the denitrification tank. Activated sludge is also affected by cyanide, and growth is inhibited when the cyan concentration reaches about 50 ppm or more in the aeration tank. However, according to the present invention, when ammonia is removed by steam stripping, cyan in the surplus gas liquid is also easily distilled off, so that the subsequent wastewater treatment system is prevented from being hindered by cyan in the surplus gas liquid. can do. Furthermore, in the present invention, the minimum amount of steam stripping may be performed according to the amount of ammonia to be removed from the wastewater so that the ammonia amount flowing into the wastewater treatment system has a predetermined value. Can be saved significantly. For example, on average, the surplus gas liquid is brought into the wastewater treatment system at 195 kg / hr free ammonia and 105 kg / hr fixed ammonia, and the wastewater treatment system uses 100 kg / hr ammonia content from other sources as wastewater treatment system. However, it is assumed that only the ammonia content of 300 kg / hr can be introduced into the subsequent wastewater treatment system due to the restriction of the ammonia content in the wastewater discharged to the public water area. If the amount of waste water and its ammonia concentration are always constant, 100 kg / hr of the free ammonia in the surplus gas liquid may be removed by steam stripping. If the removal rate of free ammonia by steam stripping is 90%, about 57% of the surplus gas liquid may be used for steam stripping. However, if the ammonia content of wastewater from other discharge sources reaches 150 kg / hr at the maximum, even in this case, only 300 kg / hr of ammonia can flow into the subsequent wastewater treatment system. 150 kg / hr of free ammonia in the gas liquid must be removed. For this purpose, about 86% of the surplus gas liquid must be used for steam stripping, and the surplus gas liquid used for steam stripping increases by about 50%. Since the amount of liquid used for steam stripping is substantially proportional to the amount of steam consumed, the amount of steam consumed also increases by about 50%. As is clear from this assumed case, when steam stripping is always performed with sufficient margin so that the amount of ammonia brought into the wastewater can be changed, the ammonia in the steam stripping depends on the amount of ammonia brought into the wastewater. Compared with the case where the removal amount is adjusted, the steam consumption is remarkably increased. In addition, the activated sludge in the subsequent wastewater treatment system is also difficult to manage because the concentration of ammonia varies.
[Brief description of the drawings]
FIG. 1 shows an example of a liquid flow when steam stripping of surplus gas liquid is performed according to the method of the present invention.
[Explanation of symbols]
1 Supply pipe for
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29687197A JP3755259B2 (en) | 1997-10-29 | 1997-10-29 | Wastewater treatment method in coke production facility |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29687197A JP3755259B2 (en) | 1997-10-29 | 1997-10-29 | Wastewater treatment method in coke production facility |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11128972A JPH11128972A (en) | 1999-05-18 |
| JP3755259B2 true JP3755259B2 (en) | 2006-03-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29687197A Expired - Fee Related JP3755259B2 (en) | 1997-10-29 | 1997-10-29 | Wastewater treatment method in coke production facility |
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| Country | Link |
|---|---|
| JP (1) | JP3755259B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2817547B1 (en) * | 2000-12-01 | 2003-08-22 | Total Raffinage Distribution | METHOD AND DEVICE FOR THE CONTINUOUS TREATMENT OF WASTE WATER OF INDUSTRIAL ORIGIN BY WATER VAPOR STRIPPING |
| JP3709824B2 (en) * | 2001-10-09 | 2005-10-26 | 富士電機システムズ株式会社 | Control method of nitrogen removal process |
| JP4764095B2 (en) * | 2005-08-05 | 2011-08-31 | 新日鉄エンジニアリング株式会社 | Purification method of gasification gas |
| CN105948306B (en) * | 2016-05-12 | 2018-09-21 | 华陆工程科技有限责任公司 | A kind of pretreatment of coal gasification waste water exhaust gas and method of comprehensive utilization |
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1997
- 1997-10-29 JP JP29687197A patent/JP3755259B2/en not_active Expired - Fee Related
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| Publication number | Publication date |
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| JPH11128972A (en) | 1999-05-18 |
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