JP5391577B2 - Hydrochloric acid recovery device and hydrochloric acid recovery method for recovering hydrochloric acid from waste hydrochloric acid solution - Google Patents

Hydrochloric acid recovery device and hydrochloric acid recovery method for recovering hydrochloric acid from waste hydrochloric acid solution Download PDF

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JP5391577B2
JP5391577B2 JP2008127258A JP2008127258A JP5391577B2 JP 5391577 B2 JP5391577 B2 JP 5391577B2 JP 2008127258 A JP2008127258 A JP 2008127258A JP 2008127258 A JP2008127258 A JP 2008127258A JP 5391577 B2 JP5391577 B2 JP 5391577B2
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hydrochloric acid
absorption tower
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JP2009274906A (en
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努 杉山
重史 桂
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JFE Steel Corp
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本発明は、鋼材の酸洗設備にて発生する廃塩酸液から塩酸を回収する装置および方法に関するものである。   The present invention relates to an apparatus and method for recovering hydrochloric acid from a waste hydrochloric acid solution generated in a steel pickling facility.

鋼材の酸洗設備にて発生する廃塩酸液から塩酸を回収する技術は、従来から種々検討されている（たとえば特許文献１等）。それらの技術は、いずれも廃塩酸液に含まれるFeCl2を分解して塩酸（ＨCl）を回収するものであり、その工程は図２に示す通りである。なお、ここでは図２を参照して、FeCl2を分解するリアクターとして培焼炉リアクターを用いる例について説明する。 Various techniques for recovering hydrochloric acid from a waste hydrochloric acid solution generated in a steel pickling facility have been conventionally studied (for example, Patent Document 1). In any of these techniques, FeCl 2 contained in the waste hydrochloric acid solution is decomposed to recover hydrochloric acid (HC1), and the process is as shown in FIG. Here, with reference to FIG. 2, an example in which a culture furnace reactor is used as a reactor for decomposing FeCl 2 will be described.

廃塩酸液は、図２に示す通り、廃塩酸液配管１を介して培焼炉リアクター２へ導入される。培焼炉リアクター２内でFeCl2の分解反応（４FeCl2＋４Ｈ2Ｏ＋Ｏ2→２Fe2Ｏ3＋８ＨCl）が進行する。
この分解反応で発生したＨClを含有するガス（以下、塩酸含有ガスという）は、塩酸含有ガス配管３を介して第１吸収塔５へ導入される。なお、従来の技術で使用する吸収塔は１機であり、その吸収塔に番号を付す必要はないが、本発明との差異を示すために第１吸収塔と記す。 As shown in FIG. 2, the waste hydrochloric acid solution is introduced into the culture furnace reactor 2 through the waste hydrochloric acid solution pipe 1. The decomposition reaction of FeCl 2 (4FeCl 2 + 4H 2 O + O 2 → 2Fe 2 O 3 + 8HCl) proceeds in the brewing furnace reactor 2.
A gas containing HCl generated by this decomposition reaction (hereinafter referred to as hydrochloric acid-containing gas) is introduced into the first absorption tower 5 through the hydrochloric acid-containing gas pipe 3. In addition, although the absorption tower used by the prior art is one machine, it is not necessary to attach | subject a number to the absorption tower, In order to show the difference with this invention, it describes as a 1st absorption tower.

第１吸収塔５には水配管４を介して水が供給され、第１吸収塔５内で塩酸含有ガスに噴霧される。そして、噴霧される水に塩酸含有ガス中のＨClが溶解して塩酸水溶液となり、塩酸回収配管11を介して回収される。
その一方で、第１吸収塔５から排出される排ガス（以下、第１排ガスという）は、第１排気配管６を介して洗浄塔（図示せず）へ導入される。第１排ガスにはＨClが残留しているので、洗浄塔内で中和剤（たとえばNaＯＨ等）を注入して中和処理を施す。第１排ガスにＨClが多量に残留する場合は、中和剤の消費量が増大して、塩酸回収コストが上昇する。 Water is supplied to the first absorption tower 5 through the water pipe 4 and sprayed onto the hydrochloric acid-containing gas in the first absorption tower 5. Then, HCl in the hydrochloric acid-containing gas is dissolved in the sprayed water to form a hydrochloric acid aqueous solution, which is recovered through the hydrochloric acid recovery pipe 11.
On the other hand, exhaust gas discharged from the first absorption tower 5 (hereinafter referred to as first exhaust gas) is introduced into the cleaning tower (not shown) via the first exhaust pipe 6. Since HCl remains in the first exhaust gas, neutralization is performed by injecting a neutralizing agent (for example, NaOH or the like) in the washing tower. If a large amount of HCl remains in the first exhaust gas, the consumption of the neutralizing agent increases and the hydrochloric acid recovery cost increases.

そのため、第１吸収塔５におけるＨClの回収効率を高める必要がある。ところが第１吸収塔５のみを使用する従来の技術でＨClの回収効率を高めるためには、その第１吸収塔５を大型化せざるを得ないので、大規模な設備投資が必要となる。
また従来の技術では、ＨClの回収効率が低いという問題の他に、塩酸含有ガス配管３や第１排気配管６に配設される排気ファン13が振動するという問題がある。その振動は、培焼炉リアクター２内で発生するFe2Ｏ3の微粒子が塩酸含有ガスや第１排ガスに混入して排気ファン13の羽に付着し、羽の重心が変動することによって生じるものである。したがってFe2Ｏ3の微粒子の付着量が増加すれば、排気ファン13の振動が大きくなり、塩酸回収装置の稼動に支障をきたすので、定期的に排気ファン13を分解洗浄する等のメンテナンスの負荷が増大する。
特開昭57-61602号公報 Therefore, it is necessary to increase the recovery efficiency of HCl in the first absorption tower 5. However, in order to increase the recovery efficiency of HCl by the conventional technique using only the first absorption tower 5, the first absorption tower 5 must be enlarged, and therefore, a large-scale capital investment is required.
In addition to the problem that the recovery efficiency of HCl is low, the conventional technique has a problem that the exhaust fan 13 disposed in the hydrochloric acid-containing gas pipe 3 and the first exhaust pipe 6 vibrates. The vibration is caused by Fe 2 O 3 fine particles generated in the brewing furnace reactor 2 being mixed with hydrochloric acid-containing gas or first exhaust gas and adhering to the wings of the exhaust fan 13, and the centroid of the wings fluctuating. It is. Therefore, if the adhesion amount of Fe 2 O 3 particles increases, the vibration of the exhaust fan 13 will increase and the operation of the hydrochloric acid recovery unit will be hindered. Therefore, maintenance loads such as periodically disassembling and cleaning the exhaust fan 13 will be required. Will increase.
JP-A-57-61602

本発明は、鋼材の酸洗設備にて発生する廃塩酸液から塩酸を効率良く回収するとともに、設備投資の増加を抑制し、かつ設備機器のメンテナンスの負荷を軽減できる塩酸回収装置および塩酸回収方法を提供することを目的とする。   The present invention relates to a hydrochloric acid recovery apparatus and a hydrochloric acid recovery method capable of efficiently recovering hydrochloric acid from a waste hydrochloric acid solution generated in a steel pickling facility, suppressing an increase in capital investment, and reducing a load of maintenance on equipment. The purpose is to provide.

本発明は、鋼材の酸洗設備で発生する廃塩酸液から塩酸を回収する塩酸回収装置であって、廃塩酸液から塩酸含有ガスを分離するリアクターと、塩酸含有ガスに洗浄水を噴霧して塩酸水溶液と第１排ガスに分離する第１吸収塔と、第１排ガスに循環使用する洗浄水を噴射して希塩酸水溶液と第２排ガスに分離する第２吸収塔と、塩酸含有ガスをリアクターから第１吸収塔へ導入する塩酸含有ガス配管と、第１排ガスを第１吸収塔から第２吸収塔へ導入する第１排気配管と、塩酸水溶液を第１吸収塔から回収する塩酸回収配管と、第２排ガスを第２吸収塔から洗浄塔へ導入する第２排気配管と、希塩酸水溶液を第２吸収塔から回収しさらに第２吸収塔へ循環させる循環配管と、循環配管から分岐して希塩酸水溶液の一部を第１吸収塔へ導入する分岐配管と、第２排気配管に配設される排気ファンの羽に第２吸収塔から回収した希塩酸水溶液を噴霧するためのファン洗浄用配管と、を有する塩酸回収装置である。   The present invention relates to a hydrochloric acid recovery device for recovering hydrochloric acid from waste hydrochloric acid solution generated in a steel pickling facility, a reactor for separating hydrochloric acid-containing gas from waste hydrochloric acid solution, and spraying cleaning water on the hydrochloric acid-containing gas. A first absorption tower for separating hydrochloric acid aqueous solution and first exhaust gas, a second absorption tower for injecting wash water to be circulated into the first exhaust gas to separate into dilute hydrochloric acid aqueous solution and second exhaust gas, and a hydrochloric acid-containing gas from the reactor A hydrochloric acid-containing gas pipe for introducing the first absorption tower, a first exhaust pipe for introducing the first exhaust gas from the first absorption tower to the second absorption tower, a hydrochloric acid recovery pipe for recovering the hydrochloric acid aqueous solution from the first absorption tower, (2) A second exhaust pipe for introducing exhaust gas from the second absorption tower to the washing tower, a circulation pipe for collecting the diluted hydrochloric acid aqueous solution from the second absorption tower and circulating it to the second absorption tower, and a dilute hydrochloric acid aqueous solution branched from the circulation pipe. Part of it is introduced into the first absorption tower And 岐配 tube, a hydrochloric acid recovery device having a fan cleaning pipe for spraying the recovered aqueous dilute hydrochloric acid solution from the second absorption tower to blades of the exhaust fan is disposed in the second exhaust pipe.

本発明の塩酸回収装置においては、排気ファンの羽に噴霧した希塩酸水溶液を回収して第２吸収塔へ導入する希塩酸回収配管を有することが好ましい。また、リアクターが廃塩酸液中のFeCl 2 を分解して酸化鉄と塩酸含有ガスを分離するものであることが好ましい。
また本発明は、鋼材の酸洗設備で発生する廃塩酸液から塩酸を回収する塩酸回収方法において、廃塩酸液をリアクターに導入して酸化鉄と塩酸含有ガスに分離し、塩酸含有ガスを第１吸収塔に導入して洗浄水を噴射することによって塩酸水溶液と第１排ガスに分離し、塩酸水溶液を回収する一方で、第１排ガスを第２吸収塔へ導入して循環使用する洗浄水を噴射することによって希塩酸水溶液と第２排ガスに分離し、第２排ガスを洗浄塔へ導入するとともに、希塩酸水溶液を第２吸収塔に循環させ、かつ希塩酸水溶液の一部を第１吸収塔へ導入し、さらに希塩酸水溶液の一部を第２排ガスの配管に配設される排気ファンの羽に噴霧する塩酸回収方法である。 The hydrochloric acid recovery apparatus of the present invention preferably has a diluted hydrochloric acid recovery pipe for recovering the diluted hydrochloric acid aqueous solution sprayed on the blades of the exhaust fan and introducing it into the second absorption tower. Further, it is preferable that the reactor decomposes FeCl 2 in the waste hydrochloric acid solution to separate iron oxide and hydrochloric acid-containing gas.
Further, the present invention provides a hydrochloric acid recovery method for recovering hydrochloric acid from a waste hydrochloric acid solution generated in a steel pickling facility, wherein the waste hydrochloric acid solution is introduced into a reactor and separated into iron oxide and a hydrochloric acid-containing gas, The aqueous solution of hydrochloric acid and the first exhaust gas are separated by being introduced into one absorption tower and sprayed with washing water, and the aqueous hydrochloric acid solution is recovered, while the washing water to be circulated by introducing the first exhaust gas into the second absorption tower is used. The dilute hydrochloric acid aqueous solution and the second exhaust gas are separated by injection, the second exhaust gas is introduced into the cleaning tower, the dilute hydrochloric acid aqueous solution is circulated to the second absorption tower, and a part of the dilute hydrochloric acid aqueous solution is introduced into the first absorption tower. Furthermore, this is a hydrochloric acid recovery method in which a part of the dilute hydrochloric acid aqueous solution is sprayed on the wings of an exhaust fan disposed in the pipe of the second exhaust gas.

本発明の塩酸回収方法においては、排気ファンの羽に噴霧した希塩酸水溶液を回収して第２吸収塔へ導入することが好ましい。また、廃塩酸液を前記リアクターに導入して廃塩酸液中のFeCl 2 を分解して酸化鉄と塩酸含有ガスに分離することが好ましい。 In the hydrochloric acid recovery method of the present invention, it is preferable that the diluted hydrochloric acid aqueous solution sprayed on the exhaust fan blades is recovered and introduced into the second absorption tower. Further, it is preferable to introduce a waste hydrochloric acid solution into the reactor to decompose FeCl 2 in the waste hydrochloric acid solution and separate it into iron oxide and hydrochloric acid-containing gas.

本発明によれば、鋼材の酸洗設備にて発生する廃塩酸液から塩酸を効率良く回収できる。また、本発明を適用するための既存設備の改造工事あるいは新規設備の建設工事における設備投資の増加を抑制できる。さらに、稼動後のメンテナンスの負荷を軽減でき、かつ稼働率を向上できる。   According to the present invention, hydrochloric acid can be efficiently recovered from a waste hydrochloric acid solution generated in a steel pickling facility. In addition, it is possible to suppress an increase in capital investment in remodeling existing facilities or constructing new facilities for applying the present invention. Furthermore, the maintenance load after operation can be reduced and the operation rate can be improved.

図１は、本発明を適用して塩酸を回収する工程の例を示すフロー図である。鋼材の酸洗設備にて発生する廃塩酸液は、図１に示す通り、廃塩酸液配管１を介して培焼炉リアクター２へ導入される。廃塩酸液には塩素がFeCl2として含有されており、培焼炉リアクター２内でFeCl2の分解反応（４FeCl2＋４Ｈ2Ｏ＋Ｏ2→２Fe2Ｏ3＋８ＨCl）が進行する。
この分解反応で発生したＨClを含有するガス（すなわち塩酸含有ガス）は、塩酸含有ガス配管３を介して第１吸収塔５へ導入される。第１吸収塔５には循環配管９から分岐された分岐配管10を介して希塩酸水溶液が供給され、第１吸収塔５内で塩酸含有ガスに噴霧される。そして、噴霧される希塩酸水溶液に塩酸含有ガス中のＨClが溶解して塩酸水溶液となり、塩酸回収配管11を介して回収される。 FIG. 1 is a flowchart showing an example of a process for recovering hydrochloric acid by applying the present invention. As shown in FIG. 1, the waste hydrochloric acid solution generated in the steel pickling equipment is introduced into the culture furnace reactor 2 through the waste hydrochloric acid solution pipe 1. The waste hydrochloric acid solution are contained chlorine as FeCl 2, the decomposition reaction of FeCl 2 in roasting furnace reactor within 2 (4FeCl 2 + 4H 2 O + O 2 → 2Fe 2 O 3 + 8HCl) progresses.
A gas containing HCl generated by the decomposition reaction (that is, hydrochloric acid-containing gas) is introduced into the first absorption tower 5 through the hydrochloric acid-containing gas pipe 3. A dilute hydrochloric acid aqueous solution is supplied to the first absorption tower 5 through a branch pipe 10 branched from the circulation pipe 9 and sprayed onto the hydrochloric acid-containing gas in the first absorption tower 5. Then, HCl in the hydrochloric acid-containing gas is dissolved in the sprayed dilute hydrochloric acid solution to form a hydrochloric acid aqueous solution, which is collected through the hydrochloric acid collection pipe 11.

その一方で、第１吸収塔５から排出される排ガス（すなわち第１排ガス）は、第１排気配管６を介して第２吸収塔７へ導入される。第２吸収塔７には循環配管９を介して循環使用される洗浄水が供給され、第２吸収塔７内で第１排ガスに噴霧される。その結果、第１排ガスに残留するＨClが洗浄水に溶解して、希塩酸水溶液となる。循環使用することで塩酸濃度が上昇するが、第１排ガスに残留するＨClの溶解によって生じる塩酸濃度の上昇はわずかである。そのため、ここでは第１排ガスに噴霧する前の洗浄水とＨClが溶解して塩酸濃度がわずかに上昇した希塩酸水溶液とを特に区別せず、それらを総称して希塩酸水溶液と記す。   On the other hand, the exhaust gas discharged from the first absorption tower 5 (that is, the first exhaust gas) is introduced into the second absorption tower 7 through the first exhaust pipe 6. Wash water used for circulation is supplied to the second absorption tower 7 through the circulation pipe 9 and sprayed on the first exhaust gas in the second absorption tower 7. As a result, HCl remaining in the first exhaust gas is dissolved in the washing water to form a dilute hydrochloric acid aqueous solution. Although the hydrochloric acid concentration increases by circulating, the increase in the hydrochloric acid concentration caused by the dissolution of HCl remaining in the first exhaust gas is slight. Therefore, here, the washing water before spraying on the first exhaust gas and the dilute hydrochloric acid aqueous solution in which HCl dissolves and the hydrochloric acid concentration slightly increases are not particularly distinguished, and they are collectively referred to as dilute hydrochloric acid aqueous solution.

第１排ガス中のＨClを溶解した希塩酸水溶液は、循環配管９を介して再び第２吸収塔７へ導入されて、第１排ガスに噴霧される。
希塩酸水溶液の一部は、分岐配管10を介して第１吸収塔５へ導入される。その希塩酸水溶液は、塩酸含有ガスに噴霧され、塩酸含有ガス中のＨClが溶解することによって塩酸水溶液となり、塩酸回収配管11を介して回収される。このようにして塩酸含有ガス中のＨClのみならず、第１排ガスに残留するＨClも塩酸水溶液として回収できる。 The dilute hydrochloric acid aqueous solution in which HCl in the first exhaust gas is dissolved is again introduced into the second absorption tower 7 through the circulation pipe 9 and sprayed on the first exhaust gas.
A part of the dilute hydrochloric acid aqueous solution is introduced into the first absorption tower 5 through the branch pipe 10. The dilute hydrochloric acid aqueous solution is sprayed onto the hydrochloric acid-containing gas, and HCl in the hydrochloric acid-containing gas dissolves to become a hydrochloric acid aqueous solution, which is recovered through the hydrochloric acid recovery pipe 11. In this way, not only HCl in the hydrochloric acid-containing gas but also HCl remaining in the first exhaust gas can be recovered as an aqueous hydrochloric acid solution.

希塩酸水溶液の一部を第１吸収塔５へ導入することによって、第２吸収塔７で循環使用する希塩酸水溶液の循環量が減少する。そこで、必要に応じて第２吸収塔７へ水配管４を介して水を供給して希塩酸水溶液の循環量を維持する。第２吸収塔７へ水を導入することによって希塩酸水溶液の塩酸濃度が低下するが、循環使用する上で問題はない。むしろ、希塩酸水溶液の循環使用による塩酸濃度の過剰な上昇を防止できるので、設備機器の腐食を防止するとともに、塩酸の安定した回収が可能となる。   By introducing a part of the dilute hydrochloric acid aqueous solution into the first absorption tower 5, the circulation amount of the dilute hydrochloric acid aqueous solution circulated in the second absorption tower 7 is reduced. Therefore, if necessary, water is supplied to the second absorption tower 7 through the water pipe 4 to maintain the circulation amount of the dilute hydrochloric acid aqueous solution. By introducing water into the second absorption tower 7, the hydrochloric acid concentration of the dilute hydrochloric acid aqueous solution is lowered, but there is no problem in recycling. Rather, excessive increase in the concentration of hydrochloric acid due to the circulating use of dilute hydrochloric acid solution can be prevented, so that corrosion of equipment can be prevented and stable recovery of hydrochloric acid can be achieved.

第２吸収塔７から排出される排ガス（以下、第２排ガスという）は、第２排気配管８を介して洗浄塔（図示せず）へ導入される。第２排ガスには極めて微量のＨClが残留しているので、洗浄塔内で中和剤（たとえばNaＯＨ等）を注入して中和処理を施す。その際、使用する中和剤は、ＨClの残留濃度が極めて微量であるから少量で良い。
以上に説明した通り、本発明によれば廃塩酸液から塩酸を効率良く回収できる。しかも本発明では小型の吸収塔を２機使用するので、既存の吸収塔（１機）に第２吸収塔を併設すれば良く、改造工事の設備投資の増加を抑制できる。また新たに吸収塔を２機新設する場合も、大型の吸収塔の新設に比べて、建設工事の設備投資の増加を抑制できる。 Exhaust gas discharged from the second absorption tower 7 (hereinafter referred to as second exhaust gas) is introduced into the cleaning tower (not shown) via the second exhaust pipe 8. Since a very small amount of HCl remains in the second exhaust gas, neutralization is performed by injecting a neutralizing agent (such as NaOH) in the washing tower. At that time, the neutralizing agent to be used may be a small amount because the residual concentration of HCl is extremely small.
As explained above, according to the present invention, hydrochloric acid can be efficiently recovered from the waste hydrochloric acid solution. In addition, since two small absorption towers are used in the present invention, it is only necessary to add a second absorption tower to an existing absorption tower (one machine), and an increase in capital investment for remodeling work can be suppressed. Also, when two new absorption towers are newly installed, an increase in capital investment for construction work can be suppressed as compared to the construction of a large absorption tower.

さらに本発明では、第２吸収塔７で循環使用する希塩酸水溶液の一部を用いて、第２排気配管８に配設される排気ファン13を洗浄する。希塩酸水溶液で排気ファン13を洗浄するための配管をファン洗浄用配管12として図１に示す。
つまり、培焼炉リアクター２内でFe2Ｏ3の微粒子が発生するのは避けられず、その微粒子が塩酸含有ガス，第１排ガス，第２排ガスに混入して排気ファン13の羽に付着するので、希塩酸水溶液を排気ファン13の羽に噴霧することによってFe2Ｏ3の微粒子を溶解して洗い流す。その結果、排気ファン13の振動を防止でき、メンテナンスの負荷を軽減できる。しかも排気ファン13の洗浄や交換のための稼動停止を削減できるので、塩酸回収装置の稼働率が向上する。なお、希塩酸水溶液の塩酸濃度は低いので、排気ファン13の腐食は発生し難いが、耐食性の素材（たとえばチタン材等）からなる排気ファンを使用することが好ましい。 Further, in the present invention, the exhaust fan 13 disposed in the second exhaust pipe 8 is washed using a part of the dilute hydrochloric acid aqueous solution circulated and used in the second absorption tower 7. A pipe for cleaning the exhaust fan 13 with dilute hydrochloric acid aqueous solution is shown in FIG.
That is, it is inevitable that Fe 2 O 3 fine particles are generated in the brewing furnace reactor 2, and the fine particles are mixed with hydrochloric acid-containing gas, first exhaust gas, and second exhaust gas and adhere to the wings of the exhaust fan 13. Therefore, the Fe 2 O 3 fine particles are dissolved and washed away by spraying dilute hydrochloric acid aqueous solution onto the wings of the exhaust fan 13. As a result, the vibration of the exhaust fan 13 can be prevented and the maintenance load can be reduced. In addition, since the operation stop for cleaning and replacement of the exhaust fan 13 can be reduced, the operating rate of the hydrochloric acid recovery device is improved. Since the hydrochloric acid concentration of the dilute hydrochloric acid aqueous solution is low, corrosion of the exhaust fan 13 hardly occurs, but it is preferable to use an exhaust fan made of a corrosion-resistant material (for example, titanium material).

塩酸濃度の低い希塩酸水溶液を用いて排気ファン13の洗浄を行なうので、排気ファン13が腐食する惧れはなく、常に希塩酸水溶液を噴霧できる。そのため、制御系を非常に簡素化でき、設備故障等を大幅に低減できる。
また、排気ファン13の羽に噴霧した希塩酸水溶液を回収して、第２吸収塔へ導入しても良い。希塩酸水溶液を排気ファン13から回収して第２吸収塔へ導入する配管（以下、希塩酸回収配管という）を設けることによって、希塩酸水溶液が第２吸収塔から第１吸収塔５へ導入されるので、希塩酸水溶液中のＨClも塩酸水溶液として回収できる。なお図１では、希塩酸回収配管は図示を省略する。 Since the exhaust fan 13 is cleaned using a dilute hydrochloric acid aqueous solution having a low hydrochloric acid concentration, the exhaust fan 13 is not likely to be corroded, and the dilute hydrochloric acid aqueous solution can always be sprayed. Therefore, the control system can be greatly simplified, and equipment failures can be greatly reduced.
Further, the diluted hydrochloric acid aqueous solution sprayed on the wings of the exhaust fan 13 may be collected and introduced into the second absorption tower. Since a dilute hydrochloric acid aqueous solution is introduced from the second absorption tower to the first absorption tower 5 by providing a pipe for collecting the dilute hydrochloric acid aqueous solution from the exhaust fan 13 and introducing it to the second absorption tower (hereinafter referred to as dilute hydrochloric acid collection pipe). HCl in the dilute hydrochloric acid aqueous solution can also be recovered as a hydrochloric acid aqueous solution. In FIG. 1, the dilute hydrochloric acid recovery pipe is not shown.

図１に示すように吸収塔を２機使用して、廃塩酸液から塩酸を回収した。すなわち、廃塩酸液を培焼炉リアクター２へ導入して廃塩酸液中のFeCl2を分解し、得られた塩酸含有ガスを第１吸収塔５へ導入し、さらに水を噴霧した。第１吸収塔５から排出される第１排ガスを第２吸収塔７へ導入して希塩酸水溶液を噴霧した。その希塩酸水溶液を第２吸収塔７で循環使用しながら、希塩酸水溶液の一部を第１吸収塔５へ導入して、水とともに塩酸含有ガスに噴霧した。このようにして得られた塩酸水溶液を第１吸収塔から回収した。また第２吸収塔７で循環使用する希塩酸水溶液の一部を用いて、第２排気配管８に配設される排気ファン13を洗浄した。さらに、必要に応じて第２吸収塔へ洗浄水を導入することによって、希塩酸水溶液の循環量を維持した。第２吸収塔７から排出される第２排ガスは、洗浄塔（図示せず）で中和処理を施した後、煙突から放散した。これを発明例とする。 As shown in FIG. 1, hydrochloric acid was recovered from the waste hydrochloric acid solution using two absorption towers. That is, the waste hydrochloric acid solution was introduced into the culture furnace reactor 2 to decompose FeCl 2 in the waste hydrochloric acid solution, and the resulting hydrochloric acid-containing gas was introduced into the first absorption tower 5 and further sprayed with water. The 1st exhaust gas discharged | emitted from the 1st absorption tower 5 was introduce | transduced into the 2nd absorption tower 7, and the dilute hydrochloric acid aqueous solution was sprayed. While the dilute hydrochloric acid aqueous solution was circulated and used in the second absorption tower 7, a part of the dilute hydrochloric acid aqueous solution was introduced into the first absorption tower 5 and sprayed onto the hydrochloric acid-containing gas together with water. The hydrochloric acid aqueous solution thus obtained was recovered from the first absorption tower. Further, the exhaust fan 13 disposed in the second exhaust pipe 8 was cleaned using a part of the diluted hydrochloric acid aqueous solution circulated in the second absorption tower 7. Furthermore, the circulation amount of dilute hydrochloric acid aqueous solution was maintained by introducing wash water into the second absorption tower as necessary. The second exhaust gas discharged from the second absorption tower 7 was neutralized by a washing tower (not shown) and then diffused from the chimney. This is an invention example.

一方、従来は図２に示すように、吸収塔を１機使用して廃塩酸液から塩酸を回収していた。すなわち、廃塩酸液を培焼炉リアクター２へ導入して廃塩酸液中のFeCl2を分解し、得られた塩酸含有ガスを第１吸収塔５へ導入し、さらに水を噴霧した。このようにして得られた塩酸水溶液を第１吸収塔５から回収した。第１吸収塔５から排出される第１排ガスは、洗浄塔（図示せず）で中和処理を施した後、煙突から放散した。これを従来例とする。 On the other hand, conventionally, as shown in FIG. 2, hydrochloric acid was recovered from the waste hydrochloric acid solution using one absorption tower. That is, the waste hydrochloric acid solution was introduced into the culture furnace reactor 2 to decompose FeCl 2 in the waste hydrochloric acid solution, and the resulting hydrochloric acid-containing gas was introduced into the first absorption tower 5 and further sprayed with water. The hydrochloric acid aqueous solution thus obtained was recovered from the first absorption tower 5. The first exhaust gas discharged from the first absorption tower 5 was neutralized by a washing tower (not shown) and then diffused from the chimney. This is a conventional example.

塩酸回収装置を稼動させた６ケ月の期間中に、排気ファンの洗浄を行なった回数は、発明例が皆無であったのに対して、従来例は９回であった。このことから、本発明を適用すればメンテナンスの負荷を軽減できることが確かめられた。
さらに、上記のメンテナンス負荷の軽減によって、稼働率の向上および塩酸回収効率の向上が確かめられた。 During the period of 6 months when the hydrochloric acid recovery unit was operated, the exhaust fan was cleaned the number of times of the invention example, while that of the conventional example was 9 times. From this, it was confirmed that the maintenance load can be reduced by applying the present invention.
Furthermore, by reducing the maintenance load, it was confirmed that the operating rate and hydrochloric acid recovery efficiency were improved.

本発明を適用して塩酸を回収する工程の例を示すフロー図である。It is a flowchart which shows the example of the process of collect | recovering hydrochloric acids by applying this invention. 従来の塩酸を回収する工程を示すフロー図である。It is a flowchart which shows the process of collect | recovering the conventional hydrochloric acid.

符号の説明Explanation of symbols

１ 廃塩酸液配管
２ 培焼炉リアクター
３ 塩酸含有ガス配管
４ 水配管
５ 第１吸収塔
６ 第１排気配管
７ 第２吸収塔
８ 第２排気配管
９ 循環配管
10 分岐配管
11 塩酸回収配管
12 ファン洗浄用配管
13 排気ファン
DESCRIPTION OF SYMBOLS 1 Waste hydrochloric acid liquid piping 2 Culture furnace reactor 3 Hydrochloric acid containing gas piping 4 Water piping 5 1st absorption tower 6 1st exhaust piping 7 2nd absorption tower 8 2nd exhaust piping 9 Circulation piping
10 Branch piping
11 Hydrochloric acid recovery pipe
12 Fan cleaning piping
13 Exhaust fan

Claims (6)

鋼材の酸洗設備で発生する廃塩酸液から塩酸を回収する塩酸回収装置であって、前記廃塩酸液から塩酸含有ガスを分離するリアクターと、前記塩酸含有ガスに洗浄水を噴霧して塩酸水溶液と第１排ガスに分離する第１吸収塔と、前記第１排ガスに循環使用する洗浄水を噴射して希塩酸水溶液と第２排ガスに分離する第２吸収塔と、前記塩酸含有ガスを前記リアクターから前記第１吸収塔へ導入する塩酸含有ガス配管と、前記第１排ガスを前記第１吸収塔から前記第２吸収塔へ導入する第１排気配管と、前記塩酸水溶液を前記第１吸収塔から回収する塩酸回収配管と、前記第２排ガスを前記第２吸収塔から洗浄塔へ導入する第２排気配管と、前記希塩酸水溶液を前記第２吸収塔から回収しさらに前記第２吸収塔へ循環させる循環配管と、前記循環配管から分岐して前記希塩酸水溶液の一部を前記第１吸収塔へ導入する分岐配管と、前記第２排気配管に配設される排気ファンの羽に前記第２吸収塔から回収した希塩酸水溶液を噴霧するためのファン洗浄用配管と、を有することを特徴とする塩酸回収装置。   A hydrochloric acid recovery device for recovering hydrochloric acid from waste hydrochloric acid generated in a steel pickling facility, a reactor for separating hydrochloric acid-containing gas from the waste hydrochloric acid, and a hydrochloric acid aqueous solution by spraying cleaning water on the hydrochloric acid-containing gas And a first absorption tower that separates the first exhaust gas, a second absorption tower that injects cleaning water to be circulated into the first exhaust gas and separates it into a dilute hydrochloric acid aqueous solution and a second exhaust gas, and the hydrochloric acid-containing gas from the reactor. A hydrochloric acid-containing gas pipe to be introduced to the first absorption tower, a first exhaust pipe to introduce the first exhaust gas from the first absorption tower to the second absorption tower, and the aqueous hydrochloric acid solution are recovered from the first absorption tower. A hydrochloric acid recovery pipe, a second exhaust pipe for introducing the second exhaust gas from the second absorption tower to the washing tower, and a circulation for recovering the dilute hydrochloric acid aqueous solution from the second absorption tower and circulating it to the second absorption tower Piping and said circulation A diverging hydrochloric acid aqueous solution recovered from the second absorption tower is branched to a branch pipe for branching off from the pipe to introduce a part of the dilute hydrochloric acid aqueous solution into the first absorption tower, and a wing of an exhaust fan disposed in the second exhaust pipe. A hydrochloric acid recovery apparatus comprising a fan cleaning pipe for spraying. 前記排気ファンの羽に噴霧した希塩酸水溶液を回収して前記第２吸収塔へ導入する希塩酸回収配管を有することを特徴とする請求項１に記載の塩酸回収装置。   2. The hydrochloric acid recovery apparatus according to claim 1, further comprising a diluted hydrochloric acid recovery pipe that recovers the diluted hydrochloric acid aqueous solution sprayed on the blades of the exhaust fan and introduces the diluted hydrochloric acid aqueous solution into the second absorption tower. 鋼材の酸洗設備で発生する廃塩酸液から塩酸を回収する塩酸回収方法において、前記廃塩酸液をリアクターに導入して酸化鉄と塩酸含有ガスに分離し、前記塩酸含有ガスを第１吸収塔に導入して洗浄水を噴射することによって塩酸水溶液と第１排ガスに分離し、前記塩酸水溶液を回収する一方で、前記第１排ガスを第２吸収塔へ導入して循環使用する洗浄水を噴射することによって希塩酸水溶液と第２排ガスに分離し、前記第２排ガスを洗浄塔へ導入するとともに、前記希塩酸水溶液を前記第２吸収塔に循環させ、かつ前記希塩酸水溶液の一部を前記第１吸収塔へ導入し、さらに前記希塩酸水溶液の一部を前記第２排ガスの配管に配設される排気ファンの羽に噴霧することを特徴とする塩酸回収方法。   In a hydrochloric acid recovery method for recovering hydrochloric acid from a waste hydrochloric acid solution generated in a steel pickling facility, the waste hydrochloric acid solution is introduced into a reactor and separated into an iron oxide and a hydrochloric acid-containing gas, and the hydrochloric acid-containing gas is separated into a first absorption tower. The aqueous solution is separated into a hydrochloric acid aqueous solution and a first exhaust gas by injecting the cleaning water into the first exhaust gas, and the hydrochloric acid aqueous solution is recovered, while the first exhaust gas is introduced into the second absorption tower and the cleaning water to be circulated is injected. In this way, the dilute hydrochloric acid aqueous solution and the second exhaust gas are separated, the second exhaust gas is introduced into the cleaning tower, the dilute hydrochloric acid aqueous solution is circulated to the second absorption tower, and a part of the dilute hydrochloric acid aqueous solution is circulated in the first absorption. A hydrochloric acid recovery method comprising introducing into a tower and spraying a part of the dilute hydrochloric acid aqueous solution onto a blade of an exhaust fan disposed in a pipe of the second exhaust gas. 前記排気ファンの羽に噴霧した希塩酸水溶液を回収して前記第２吸収塔へ導入することを特徴とする請求項３に記載の塩酸回収方法。   4. The hydrochloric acid recovery method according to claim 3, wherein a dilute hydrochloric acid aqueous solution sprayed on the blades of the exhaust fan is recovered and introduced into the second absorption tower. 前記リアクターが、前記廃塩酸液中のFeClThe reactor is FeCl in the waste hydrochloric acid solution. 22 を分解して酸化鉄と前記塩酸含有ガスを分離することを特徴とする請求項１または２に記載の塩酸回収装置。The hydrochloric acid recovery apparatus according to claim 1 or 2, wherein iron oxide and the hydrochloric acid-containing gas are separated by decomposing iron. 前記廃塩酸液を前記リアクターに導入して前記廃塩酸液中のFeClThe waste hydrochloric acid solution is introduced into the reactor and FeCl in the waste hydrochloric acid solution is introduced. 22 を分解して前記酸化鉄と前記塩酸含有ガスに分離することを特徴とする請求項３または４に記載の塩酸回収方法。The method for recovering hydrochloric acid according to claim 3 or 4, wherein the iron oxide and the hydrochloric acid-containing gas are separated by decomposition.
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