通過優(yōu)化脫硫廢水取水方式、預(yù)沉、改進(jìn)加藥管理、澄清器合理排泥等技術(shù)措施，有針對性地解決脫硫廢水處理過程中存在的問題，保證系統(tǒng)的正常運(yùn)行和出水水質(zhì)，并提出以系統(tǒng)性管理的理念來推進(jìn)脫硫廢水處理的技術(shù)管理工作。

　　By optimizing the water intake method for desulfurization wastewater, pre settling, improving dosing management, and implementing reasonable sludge discharge in clarifiers, targeted solutions are taken to address the problems in the desulfurization wastewater treatment process, ensuring the normal operation of the system and the quality of the effluent. The concept of systematic management is proposed to promote the technical management of desulfurization wastewater treatment.

　　0前言

　　0 Preface

　　脫硫廢水處理系統(tǒng)是燃煤電廠濕法煙氣脫硫工藝的重要組成部分，通過對脫硫廢水處理排出，保障脫硫裝置穩(wěn)定可靠運(yùn)行，經(jīng)過處理后脫硫廢水還必須滿足達(dá)標(biāo)排放的要求。由于脫硫裝置、燃煤種類、工藝用水、運(yùn)行工況等原因，脫硫廢水水質(zhì)成分復(fù)雜，給廢水處理帶來了不小的挑戰(zhàn)。而在處理過程中，脫硫廢水提取、預(yù)沉、加藥反應(yīng)、澄清排泥等環(huán)節(jié)各有分工，彼此又存在相互影響的關(guān)系，需要從系統(tǒng)性角度開展相關(guān)技術(shù)管理工作來解決運(yùn)行中存在的問題。

　　The desulfurization wastewater treatment system is an important component of the wet flue gas desulfurization process in coal-fired power plants. By treating and discharging the desulfurization wastewater, it ensures the stable and reliable operation of the desulfurization device. After treatment, the desulfurization wastewater must also meet the requirements for standard discharge. Due to factors such as desulfurization equipment, types of coal, process water, and operating conditions, the complex composition of desulfurization wastewater poses significant challenges to wastewater treatment. In the process of desulfurization wastewater extraction, pre sedimentation, dosing reaction, clarification and sludge discharge, each link has its own division of labor, and there is a mutual influence between them. It is necessary to carry out relevant technical management work from a systematic perspective to solve the problems that exist in operation.

　　1 脫硫廢水處理工藝流程和水質(zhì)標(biāo)準(zhǔn)

　　1. Process flow and water quality standards for desulfurization wastewater treatment

　　脫硫廢水處理的典型工藝流程如圖1 所示。脫硫廢水主要含有脫硫廢水中的懸浮物、重金屬、COD、氟離子等污染物，經(jīng)過處理后，出水水質(zhì)需要符合8978-1996《污水綜合排放標(biāo)準(zhǔn)》的要求。

　　The typical process flow of desulfurization wastewater treatment is shown in Figure 1. The desulfurization wastewater mainly contains suspended solids, heavy metals COD、 After treatment, the effluent quality of pollutants such as fluoride ions needs to meet the requirements of the 8978-1996 "Comprehensive Wastewater Discharge Standard".

　　2 脫硫廢水取水方式優(yōu)化和預(yù)沉淀

　　Optimization of water intake method and pre sedimentation for desulfurization wastewater

　　2.1 脫硫廢水取水方式優(yōu)化傳統(tǒng)設(shè)計(jì)上，脫硫廢水取自廢水旋流站的溢流液，其含固量平均值大于1.5%，最大值達(dá)5% 以上，遠(yuǎn)高于1% 的設(shè)計(jì)值。這樣的水質(zhì)經(jīng)常造成脫硫廢水池污泥沉積曝氣管堵塞、澄清器泥位過高刮泥機(jī)過載損壞、壓濾機(jī)超負(fù)荷運(yùn)行及加藥量增加等一系列問題，這些問題反過來又會影響脫硫廢水的正常處理量，形成惡性循環(huán)，最終會影響脫硫裝置的正常運(yùn)行。針對傳統(tǒng)設(shè)計(jì)的不足，根據(jù)真空皮帶機(jī)石膏濾液的含固量小且相對穩(wěn)定的特點(diǎn)，將脫硫廢水的取水點(diǎn)調(diào)整為石膏濾液。石膏漿液經(jīng)過真空皮帶機(jī)的過濾，其含固量大大降低，石膏濾液的含固量低于0.5%。經(jīng)過取水點(diǎn)的調(diào)整，基本能解決脫硫廢水含固量高所帶來的問題，也為脫硫系統(tǒng)運(yùn)行良性循環(huán)創(chuàng)造了條件。根據(jù)脫硫吸收塔內(nèi)漿液的雜質(zhì)含量來控制取水量是改善脫硫廢水處理運(yùn)行的有效方法。上下游之間可以根據(jù)吸收塔漿液中氯、氟離子、脫硫廢水重金屬的含量等指標(biāo)建立有效的協(xié)調(diào)工作機(jī)制，以降低脫硫廢水處理量。當(dāng)吸收塔漿液氯離子含量控制在10000～20000mg/L，且脫硫裝置保持正常運(yùn)行時(shí)，說明此時(shí)脫硫廢水的處理量是合理的。2.2 預(yù)沉池的沉降效果和緩沖作用脫硫廢水里的懸浮物主要成分是石膏和煤塵中的硅、鋁、鐵等氧化物，其特點(diǎn)是密度大易沉降。設(shè)置預(yù)沉池的目的就是對脫硫廢水中懸浮物進(jìn)行自然沉淀，進(jìn)一步降低脫硫廢水的含固量。有試驗(yàn)結(jié)果顯示120min 以上的沉降時(shí)間，可使脫硫廢水懸浮物濃度下降99% 以上。實(shí)際運(yùn)行中，經(jīng)過預(yù)沉池后，脫硫廢水的含固量能降低50% 以上，且進(jìn)水含固量越高，沉淀效果越好。圖1 脫硫廢水處理工藝流程圖預(yù)沉池還能起到緩沖池的作用。由于各種原因，有時(shí)脫硫廢水處理系統(tǒng)需要以低于設(shè)計(jì)值并且相對穩(wěn)定的流量才能保持正常運(yùn)行，保證出水水質(zhì)合格。脫硫廢水的來水也經(jīng)常是波段性的，利用預(yù)沉池的緩沖容量，就可以以相對穩(wěn)定的流量運(yùn)行，保證其處理效果。根據(jù)實(shí)際運(yùn)行經(jīng)驗(yàn)，當(dāng)脫硫廢水來水量為30m3/h 時(shí)，500m3以上的預(yù)沉池就可以起到較好的預(yù)沉淀和緩沖作用。

　　2.1 Optimization of desulfurization wastewater intake method In traditional design, desulfurization wastewater is taken from the overflow liquid of the wastewater cyclone station, with an average solid content greater than 1.5% and a maximum value of over 5%, far higher than the design value of 1%. Such water quality often causes a series of problems such as sludge deposition and aeration pipe blockage in the desulfurization wastewater tank, high sludge level in the clarifier, overload damage to the scraper, overload operation of the filter press, and increased dosage. These problems in turn affect the normal treatment capacity of desulfurization wastewater, forming a vicious cycle, and ultimately affecting the normal operation of the desulfurization device. In response to the shortcomings of traditional design, the water intake point for desulfurization wastewater is adjusted to gypsum filtrate based on the characteristics of low solid content and relatively stable gypsum filtrate in vacuum belt conveyor. The solid content of gypsum slurry is greatly reduced after filtration by a vacuum belt conveyor, and the solid content of gypsum filtrate is less than 0.5%. After adjusting the water intake point, the problem caused by high solid content in desulfurization wastewater can be basically solved, and it also creates conditions for the healthy operation of the desulfurization system. Controlling the water intake based on the impurity content of the slurry in the desulfurization absorption tower is an effective method to improve the operation of desulfurization wastewater treatment. An effective coordination mechanism can be established between upstream and downstream based on indicators such as chlorine, fluoride ions, and heavy metal content in the absorption tower slurry to reduce the treatment capacity of desulfurization wastewater. When the chloride ion content of the absorption tower slurry is controlled at 10000-20000mg/L and the desulfurization device is operating normally, it indicates that the treatment capacity of desulfurization wastewater is reasonable at this time. 2.2 The settling effect and buffering effect of the pre settling tank. The suspended solids in desulfurization wastewater are mainly composed of oxides such as silicon, aluminum, and iron in gypsum and coal dust, which are characterized by high density and easy settling. The purpose of setting up a pre settling tank is to naturally settle suspended solids in desulfurization wastewater, further reducing the solid content of desulfurization wastewater. Experimental results have shown that a settling time of more than 120 minutes can reduce the concentration of suspended solids in desulfurization wastewater by over 99%. In actual operation, after passing through the pre sedimentation tank, the solid content of desulfurization wastewater can be reduced by more than 50%, and the higher the solid content of the influent, the better the sedimentation effect. Figure 1: Process flow diagram of desulfurization wastewater treatment. The pre settling tank can also serve as a buffer tank. Due to various reasons, sometimes the desulfurization wastewater treatment system needs to operate at a flow rate lower than the design value and relatively stable in order to maintain normal operation and ensure that the effluent quality is qualified. The inflow of desulfurization wastewater is often frequency dependent, and by utilizing the buffer capacity of the pre settling tank, it can operate at a relatively stable flow rate to ensure its treatment efficiency. According to actual operating experience, when the inflow of desulfurization wastewater is 30m3/h, a pre settling tank of 500m3 or more can play a good role in pre settling and buffering.

　　3 石灰乳加藥和pH值控制

　　3. Lime milk dosing and pH control

　　3.1 石灰乳加藥和pH值控制脫硫廢水進(jìn)入三聯(lián)箱后，首先是加氫氧化鈣(配制成石灰乳液) 調(diào)節(jié)pH 值。脫硫廢水中帶正電荷的膠體顆粒只要達(dá)到零界pH 值9 時(shí)，膠體顆粒就會開始脫穩(wěn)凝聚。另外，氫氧化鈣還與脫硫廢水中的重金屬反應(yīng)生成氫氧化物沉淀，與氟離子反應(yīng)生成氟化鈣沉淀。石灰乳加藥與脫硫廢水各污染因子均有關(guān)系，是脫硫廢水處理過程中的關(guān)鍵環(huán)節(jié)。為保證重金屬和氟離子的去除效果，一般建議將中和箱的p H 值調(diào)整至9.0～9.5。如果石灰乳加藥量過大p H 值過高時(shí)部分兩性金屬會形成絡(luò)合物而使沉淀物發(fā)生返溶現(xiàn)象，不利于重金屬的沉淀反應(yīng)，還會浪費(fèi)藥品，并且增加廢水中含固量。當(dāng)三聯(lián)箱的pH 值大于9.5 時(shí)，也會發(fā)生三聯(lián)箱出口管道、混合箱進(jìn)出口管道結(jié)垢，造成管道流通面積變小，系統(tǒng)出力降低的情況。因此，石灰乳加藥量不宜過高。在實(shí)際運(yùn)行中，pH 值調(diào)整至9.2 左右是比較理想的工況。為控制好石灰乳加藥效果，對在線pH 計(jì)的及時(shí)維護(hù)必不可少。因?yàn)檫\(yùn)行環(huán)境較差，pH 計(jì)電極表面極易被硫酸鈣、氫氧化鈣等物質(zhì)結(jié)垢包圍，阻礙水流和離子通道，影響pH 值的正常顯示，并影響石灰乳加藥反應(yīng)效果，pH 值顯示偏大會造成加藥量不足，pH 值顯示偏小會造成加藥過量。所以，需要對在線pH計(jì)進(jìn)行定期校驗(yàn)和定期清洗，以保證其靈敏度和準(zhǔn)確性。3.2 石灰乳加藥系統(tǒng)管理運(yùn)行中，石灰乳加藥系統(tǒng)故障會比較多，主要有加藥管道堵塞、加藥泵轉(zhuǎn)子和定子卡澀、磨損等。氫氧化鈣本身是易沉積、易磨損，加上純度不高、細(xì)度不夠、配濃度過高、加藥管道設(shè)計(jì)不合理等因素，就極易造成上述問題。對此，需要針對具體情況，作出相應(yīng)的改進(jìn)措施。石灰粉應(yīng)選用氫氧化鈣含量95%以上的；石灰乳配制濃度可以由5% 調(diào)整為2%～3%；減少加藥管道彎頭；將加藥管道人工沖洗改為停運(yùn)自動沖洗程序；設(shè)置石灰乳自動加藥程序，根據(jù)pH 值變化自動調(diào)整加藥量。通過以上措施，可以減少管道沉積和泵體磨損等問題的發(fā)生，提高加藥效果。

　　3.1 After the desulfurization wastewater from lime milk dosing and pH control enters the triple header, first add calcium hydroxide (prepared into lime lotion) to adjust the pH value. When the positively charged colloidal particles in desulfurization wastewater reach the zero bound pH value of 9, the colloidal particles will begin to destabilize and coalesce. In addition, calcium hydroxide reacts with heavy metals in desulfurization wastewater to form hydroxide precipitates, and reacts with fluoride ions to form calcium fluoride precipitates. The addition of lime milk is related to various pollution factors in desulfurization wastewater and is a key link in the treatment process of desulfurization wastewater. To ensure the removal efficiency of heavy metals and fluoride ions, it is generally recommended to adjust the pH value of the neutralization box to 9.0-9.5. If the dosage of lime milk is too high and the pH value is too high, some amphoteric metals will form complexes and cause the precipitation to dissolve, which is not conducive to the precipitation reaction of heavy metals, wastes drugs, and increases the solid content in the wastewater. When the pH value of the triple box is greater than 9.5, scaling may also occur in the outlet pipes of the triple box and the inlet and outlet pipes of the mixing box, resulting in a decrease in the flow area of the pipes and a decrease in the system output. Therefore, the dosage of lime milk should not be too high. In actual operation, adjusting the pH value to around 9.2 is an ideal working condition. Timely maintenance of the online pH meter is essential to control the dosing effect of lime milk. Due to poor operating environment, the electrode surface of the pH meter is easily surrounded by substances such as calcium sulfate and calcium hydroxide, which hinder water flow and ion channels, affect the normal display of pH value, and affect the effect of lime milk dosing reaction. If the pH value is displayed too high, it will cause insufficient dosage, and if the pH value is displayed too low, it will cause excessive dosage. Therefore, it is necessary to regularly calibrate and clean the online pH meter to ensure its sensitivity and accuracy. During the management and operation of the lime milk dosing system, there will be many malfunctions, mainly including blockage of the dosing pipeline, jamming and wear of the dosing pump rotor and stator. Calcium hydroxide itself is prone to sedimentation and wear, coupled with factors such as low purity, insufficient fineness, high concentration, and unreasonable design of dosing pipelines, which can easily cause the above-mentioned problems. Corresponding improvement measures need to be taken based on specific situations. Lime powder should be selected with a calcium hydroxide content of over 95%; The concentration of lime milk can be adjusted from 5% to 2% to 3%; Reduce the number of bends in the dosing pipeline; Change the manual flushing of the dosing pipeline to the automatic shutdown flushing program; Set up an automatic lime milk dosing program to automatically adjust the dosage according to changes in pH value. Through the above measures, the occurrence of pipeline sedimentation and pump body wear can be reduced, and the dosing effect can be improved.

　　4 絮凝劑和有機(jī)硫加藥量控制

　　4. Control of dosage of coagulants and organic sulfur

　　脫硫廢水處理過程中，會加入適量的絮凝劑和助凝劑，提高絮凝沉淀效果。脫硫廢水的絮凝劑可以選用聚合鋁、聚合氯化鋁鐵、三氯化鐵等，需要根據(jù)實(shí)際水質(zhì)情況，試驗(yàn)選用合適的絮凝劑。聚合氯化鋁鐵的加藥量一般控制在15～30mg/L。脫硫廢水中的重金屬與氫氧化鈣反應(yīng)后，大部分以沉淀物的形式除去，但仍有部分殘余溶解在水中，加入有機(jī)硫的目的就是除去這些殘留的重金屬。有機(jī)硫的加藥量應(yīng)根據(jù)脫硫廢水的重金屬成分和含量進(jìn)行調(diào)整，若是來水的重金屬含量本來就很低，經(jīng)過與石灰乳反應(yīng)沉淀后，水中的含量已低于排放標(biāo)準(zhǔn)，則可降低有機(jī)硫的加藥量甚至停用，從而降低藥品的耗量和成本。

　　During the treatment of desulfurization wastewater, an appropriate amount of coagulants and coagulants are added to improve the coagulation and sedimentation effect. The coagulants for desulfurization wastewater can be selected from polyaluminum, polyaluminum ferric chloride, ferric chloride, etc. It is necessary to test and select suitable coagulants according to the actual water quality. The dosage of polyaluminum ferric chloride is generally controlled at 15-30mg/L. After the reaction between heavy metals in desulfurization wastewater and calcium hydroxide, most of them are removed in the form of precipitates, but there are still some residual dissolved in water. The purpose of adding organic sulfur is to remove these residual heavy metals. The dosage of organic sulfur should be adjusted according to the heavy metal composition and content of desulfurization wastewater. If the heavy metal content in the incoming water is already very low, and after reaction and precipitation with lime milk, the water content is lower than the emission standard, the dosage of organic sulfur can be reduced or even stopped, thereby reducing the consumption and cost of drugs.

　　5 澄清器運(yùn)行管理和污泥處理

　　5 Clarifier operation management and sludge treatment

　　如果澄清器內(nèi)泥位過高，污泥會被帶至清水區(qū)直接影響出水水質(zhì)，因此，澄清器需要做到及時(shí)排泥?？梢愿鶕?jù)澄清器的上中下三個(gè)取樣門的水樣狀況來進(jìn)行污泥排放操作。當(dāng)上部取樣門的樣水由清變渾濁，中部取樣門的水樣含泥量增多時(shí)，便可以進(jìn)行排泥操作。澄清器運(yùn)行正常時(shí)，其出水濁度可以達(dá)到小于1NTU 的水平。對污泥處理的能力直接影響澄清器和脫硫廢水處理系統(tǒng)的出力。除保證壓濾機(jī)的正常出力外，因?yàn)槊摿驈U水污泥主要成分是硫酸鈣，將污泥直接回收至脫硫漿液系統(tǒng)是污泥處理的解決方向，可以有效提高污泥處理效率和降低處理成本。

　　If the sludge level in the clarifier is too high, the sludge will be carried to the clean water area, directly affecting the effluent quality. Therefore, the clarifier needs to discharge the sludge in a timely manner. The sludge discharge operation can be carried out based on the water sample conditions of the upper, middle, and lower sampling gates of the clarifier. When the sample water from the upper sampling gate changes from clear to turbid and the sediment content of the sample from the middle sampling gate increases, the sludge discharge operation can be carried out. When the clarifier is operating normally, its effluent turbidity can reach a level of less than 1NTU. The ability to treat sludge directly affects the output of the clarifier and desulfurization wastewater treatment system. In addition to ensuring the normal output of the filter press, the main component of desulfurization wastewater sludge is calcium sulfate. Directly recycling the sludge to the desulfurization slurry system is the solution for sludge treatment, which can effectively improve sludge treatment efficiency and reduce treatment costs.

　　6 結(jié)語

　　6 Conclusion

　　脫硫廢水處理關(guān)系到脫硫裝置的正常運(yùn)行和脫硫廢水合格達(dá)標(biāo)這兩大目標(biāo)，其每個(gè)環(huán)節(jié)的工況也會影響整個(gè)脫硫廢水系統(tǒng)的運(yùn)行?？傊?，對于脫硫廢水處理主要應(yīng)從以下幾個(gè)方面推進(jìn)其技術(shù)管理工作：(1) 應(yīng)該建立系統(tǒng)性管理理念，嘗試從源頭和各處理環(huán)節(jié)的相關(guān)性上著手解決脫硫廢水處理中存在的問題。(2) 應(yīng)充分利用設(shè)備自動化條件，實(shí)現(xiàn)自動加藥自動調(diào)整水質(zhì)參數(shù)，改善脫硫廢水處理效果。(3) 污泥回收利用解決污泥處理能力受限問題，是脫硫廢水處理的一個(gè)改進(jìn)方向。(4) 隨著廢水“零排放”推進(jìn)，脫硫廢水處理還應(yīng)進(jìn)一步關(guān)注 “零排放”的技術(shù)要求，及時(shí)調(diào)整技術(shù)措施，做好技術(shù)對接工作。

　　The treatment of desulfurization wastewater is related to the normal operation of desulfurization equipment and the achievement of qualified desulfurization wastewater. The working conditions of each link will also affect the operation of the entire desulfurization wastewater system. In summary, the technical management of desulfurization wastewater treatment should mainly be promoted from the following aspects: (1) a systematic management concept should be established, and efforts should be made to solve the problems in desulfurization wastewater treatment from the source and the correlation between each treatment link. (2) We should fully utilize the automation conditions of the equipment to achieve automatic dosing and adjustment of water quality parameters, and improve the treatment effect of desulfurization wastewater. (3) Sludge recycling and utilization is an improvement direction for desulfurization wastewater treatment to solve the problem of limited sludge treatment capacity. (4) With the promotion of "zero discharge" of wastewater, desulfurization wastewater treatment should further pay attention to the technical requirements of "zero discharge", adjust technical measures in a timely manner, and do a good job in technical docking.

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