KR100743146B1 - Pretreatment method of desulfurization and denitrification waste water - Google Patents

Pretreatment method of desulfurization and denitrification waste water Download PDF

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KR100743146B1
KR100743146B1 KR1020060050287A KR20060050287A KR100743146B1 KR 100743146 B1 KR100743146 B1 KR 100743146B1 KR 1020060050287 A KR1020060050287 A KR 1020060050287A KR 20060050287 A KR20060050287 A KR 20060050287A KR 100743146 B1 KR100743146 B1 KR 100743146B1
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tank
wastewater
waste water
water
desulfurization
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KR1020060050287A
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Korean (ko)
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김충래
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김충래
주식회사 동화엔텍
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    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00Multistage treatment of water, waste water, or sewage
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/40Devices for separating or removing fatty or oily substances or similar floating material
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/52Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5236Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
    • C02F1/5245Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/52Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/54Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
    • C02F1/56Macromolecular compounds
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F5/00Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
    • C02F5/08Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00Apparatus for treatment of water, waste water or sewage
    • C02F2201/002Construction details of the apparatus
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00Specific treatment goals
    • C02F2303/22Eliminating or preventing deposits, scale removal, scale prevention

Abstract

A method for pretreating desulfurized and denitrified waste water is provided to improve the quality of condensed water generated during an evaporation and condensation process, and reuse the condensed water. A waste water, which is inputted from a raw water storage tank, is primarily precipitated in a first precipitation tank(1) to remove suspended particles from the waster water and transfer supernatant to a recycle tank(2). The supernatant is inputted into a softening tank(3). Softeners, such as Na2CO3 and Ca(OH)2, are inputted into the softening tank to precipitate and remove CaSO4 and Ca(HCO3)2 contained in the waste water using CaCO3. The waste water after the softening reaction is inputted into a coagulation tank(4). A coagulant such as FeCl3 and a coagulation supplement such as polymer are inputted into the coagulation tank to coagulate suspended particles and CaCO3 precipitators remaining in the waste water. The waste water after the coagulating reaction is secondarily precipitated in a second precipitation tank(5) to minimize suspended particles in the waste water and transfer supernatant to a neutralization tank(6). An acid is inputted into the neutralization tank to neutralize the acidity of the waste water, and the neutralized waste water is transferred to a first processed water storage tank.

Description

탈황탈질폐수의 전처리 방법{PRETREATMENT METHOD OF DESULFURIZATION AND DENITRIFICATION WASTE WATER}Pretreatment Method for Desulfurization Denitrification Wastewater {PRETREATMENT METHOD OF DESULFURIZATION AND DENITRIFICATION WASTE WATER}
도 1은 본 발명에 의한 탈황/탈질폐수의 전처리 방법을 포함하는 전체 처리공정을 나타낸 블록 흐름도.1 is a block flow diagram showing an overall treatment process including the pre-treatment method of the desulfurization / denitrification waste water according to the present invention.
도 2는 본 발명에 의한 탈황/탈질폐수의 전처리 방법을 설명하기 위해 나타낸 공정도.Figure 2 is a process diagram shown to explain the pre-treatment method of desulfurization / denitrification waste water according to the present invention.
* 도면의 주요 부분에 대한 부호의 설명 *Explanation of symbols on the main parts of the drawings
1: 1차 침전조 2: 회수조1: primary sedimentation tank 2: recovery tank
3: 연화반응조 4: 응집반응조3: softening reaction tank 4: flocculation reaction tank
5: 2차 침전조 6: 중화반응조5: secondary precipitation tank 6: neutralization reaction tank
7: 1차 처리수 저장조 8: 농축조7: Primary treatment water reservoir 8: Concentration tank
9: 탈수기 10: 진공증발농축기9: dehydrator 10: vacuum evaporator
11: 결정화장치 12: 응축기11: crystallizer 12: condenser
본 발명은 탈황/탈질폐수의 처리를 위한 방법에 관한 것으로, 더욱 상세하게는 탈황/탈질폐수 중에 함유된 염(鹽)성분들이 후처리의 증발농축공정 시에 스케일(scale)을 발생하지 않고 고농도로 증발농축될 수 있도록 전처리함으로써 응축수의 수질을 좋게 함과 아울러 재사용할 수 있도록 하는 탈황/탈질폐수의 전처리 방법에 관한 것이다.The present invention relates to a method for the treatment of desulfurization / denitrification waste water, and more particularly, the salt components contained in the desulfurization / denitrification waste water do not generate scale during the evaporation concentration process of post-treatment. The present invention relates to a method for pretreatment of desulfurization / denitrification wastewater that can be reused to improve the quality of the condensate and to reuse it.
최근 급속하게 산업이 발전함과 더불어 생활이 윤택해지면서 전력사용량이 해마다 크게 증가하고 있으며, 이에 따라 화력발전소나 열병합발전소 등지에서 전기를 생산하는데 필요한 연료 또한 많은 량이 소모되고 있다.Recently, with the rapid development of the industry, the use of electricity has increased significantly every year as the life improves, and accordingly, the fuel required for producing electricity in thermal power plants and cogeneration plants is also consumed.
이때, 전기의 생산을 위한 연료의 연소시 배연가스 중에 황산화물 및 질소산화물의 오염물질이 발생하게 되며, 탈황/탈질공정을 통해 황산화물 및 질소산화물의 오염물질을 제거하게 되는데, 이 공정에서 각종 염성분이 함유된 탈황/탈질폐수(이하 "폐수"라 한다.)가 발생하게 된다.At this time, contaminants of sulfur oxides and nitrogen oxides are generated in the flue gas during the combustion of fuel for the production of electricity, and contaminants of sulfur oxides and nitrogen oxides are removed through the desulfurization / denitrification process. Desulfurization / denitrification waste water (hereinafter referred to as “waste water”) containing salt components is generated.
부연하여, 탈황공정에서는 연소가스 중에 함유된 황산성분을 제거하기 위해 탄산칼슘(CaCO3)을 주입하게 되는데, 이 과정에서 황산화물은 다음과 같은 [화학식1] 반응으로 제거된다.In addition, in the desulfurization process, calcium carbonate (CaCO 3 ) is injected to remove sulfuric acid contained in the combustion gas. In this process, the sulfur oxide is removed by the following [Formula 1].
[화학식 1][Formula 1]
SO3 + CaCO3 = CaSO4 + CO2SO 3 + CaCO 3 = CaSO 4 + CO 2
상기 반응에서 황산화물은 황산칼슘(CaSO4) 침전물로 폐수 중에 침전하게 되고 황산칼슘(CaSO4)은 폐수에 포화상태(약 2,000ppm정도)가 되는데, 이 황산칼슘 침전물은 폐수 내에 부유물질(SS:Suspended Solids) 농도를 20,000ppm 정도까지 증가시키는 원인이 되고 있으며, 이 폐수를 증발농축처리시 포화량만큼 황산칼슘(CaSO4) 스케일을 형성하게 되므로 증발농축설비의 효율저하는 물론 잦은 화학세정을 하여야하는 문제를 일으켜 증발농축설비의 운전에 지대한 영향을 미치게 되기 때문에 전처리 공정에서 이를 극소화하여야 한다.In this reaction, sulfur oxides are precipitated in the wastewater as calcium sulfate (CaSO 4 ) precipitate, and calcium sulfate (CaSO 4 ) becomes saturated (about 2,000 ppm) in the wastewater, and the calcium sulfate precipitate is suspended in the wastewater (SS). : Suspended Solids concentration is increased to about 20,000ppm, and this wastewater forms calcium sulfate (CaSO 4 ) scale by saturation amount during evaporation concentration process. The problem must be minimized in the pretreatment process because it will have a significant effect on the operation of the evaporation plant.
뿐만 아니라, 폐수에 미량 함유된 중탄산칼슘 Ca(HCO3)2은 후처리인 증발농축공정에서 다음과 같은 [화학식2]에서와 같이 용해도가 매우 낮은 탄산칼슘(CaCO3)을 형성하게 된다.In addition, a small amount of calcium bicarbonate Ca (HCO 3 ) 2 contained in the waste water forms calcium carbonate (CaCO 3 ) having very low solubility as shown in the following [Formula 2] in an evaporative concentration process.
[화학식2][Formula 2]
Ca(HCO3)2 = CaCO3 + H2O + CO2Ca (HCO 3 ) 2 = CaCO 3 + H 2 O + CO 2
하지만, 상기 탄산칼슘(CaCO3) 또한 증발농축공정에서 스케일을 형성시키므로 증발농축에 어려움을 야기함은 물론 응축수의 수질 향상을 매우 어렵게 한다.However, the calcium carbonate (CaCO 3 ) also forms a scale in the evaporation concentration process, causing difficulty in evaporation concentration, as well as making water quality of the condensate very difficult.
이에 따라, 비효율적으로 처리된 응축수의 방류 등 탈황/탈질폐수의 처리에 따른 환경오염이 심각해지는 문제점이 있었다.Accordingly, there has been a problem that the environmental pollution caused by the treatment of desulfurization / denitrification wastewater, such as discharge of condensate treated inefficiently.
본 발명은 상기한 문제점 등을 감안하여 창출된 것으로서, 그 목적으로 하는 바는 탈황/탈질폐수 중에 함유된 염들이 증발농축공정시에 스케일을 발생하지 않고 고농도로 증발농축될 수 있도록 전처리하여 1차 처리수를 증발농축설비에 공급할 수 있게 하며 이를 통해서 후처리의 증발농축과정에서 효율저하와 잦은 화학세정을 예방하고 또 생산되는 응축수의 수질을 향상시켜 응축수를 재사용할 수 있도록 하여 탈황/탈질폐수에 의한 환경오염문제를 개선할 수 있도록 하는 탈황/탈질폐수의 전처리 방법을 제공하는데 있다.The present invention has been made in view of the above problems, and the object thereof is that the salts contained in the desulfurization / denitrification wastewater are pretreated so that they can be evaporated and concentrated at a high concentration without generating scale during the evaporation concentration process. It is possible to supply the treated water to the evaporation concentration facility, thereby preventing deterioration of efficiency and frequent chemical cleaning during the evaporation concentration process of the post-treatment, and improving the quality of the condensate produced so that the condensed water can be reused. The present invention provides a method for pretreatment of desulfurization / denitrification wastewater to improve the environmental pollution problem.
즉, 탈황/탈질폐수의 전처리 효율을 크게 향상시킬 수 있도록 하는데 있다.In other words, to improve the pretreatment efficiency of the desulfurization / denitrification waste water.
상기와 같은 목적을 달성하기 위한 본 발명은 탈황/탈질폐수의 처리를 위한 전처리 방법에 있어서, 탈황/탈질폐수의 원수저장조로부터 유입된 폐수를 1차침전조에서 1차 침전 처리하여 폐수 중의 부유물질을 최대한 제거하고 상등수를 회수조로 이송 처리하는 단계와; 상기 회수조에 저장된 상등수를 연화반응조로 유입되게 하고 상기 연화반응조에 Na2CO3과 Ca(OH)2의 연화제를 투입하여 폐수 중에 함유된 CaSO4와 Ca(HCO3)2의 각각을 CaCO3로 침전시켜 제거하는 단계와; 상기 연화반응을 마친 폐수를 응집반응조로 유입시켜 1차침전조에서 처리하고 잔류된 부유물과 연화공정에서 생성된 CaCO3 침전물들을 침전 분리하기 위해 응집제인 FeCl3와 응집보조제 인 폴리머를 투입하여 응집시키며 산성도를 조절하는 단계와; 상기 응집반응까지 마친 폐수를 2차침전조에서 2차 침전 처리하여 폐수 중에서 부유물질을 극소화시키고 상등수를 중화반응조로 이송시키는 단계와; 상기 중화반응조에 산을 투입하여 폐수의 산성도를 중화 처리하고 1차 처리수저장조로 이송시키는 단계를 포함하는 구성을 특징으로 한다.In the present invention for achieving the above object, in the pretreatment method for the treatment of desulfurization / denitrification wastewater, the first sedimentation treatment of the wastewater introduced from the raw water storage tank of the desulfurization / denitrification wastewater to the suspended solids in the wastewater Removing as much as possible and transferring the supernatant to a recovery tank; The supernatant stored in the recovery tank was introduced into a softening reactor, and a softener of Na 2 CO 3 and Ca (OH) 2 was added to the softening reactor to convert CaSO 4 and Ca (HCO 3 ) 2 contained in the wastewater into CaCO 3 . Precipitating and removing; The softened wastewater is introduced into a coagulation reactor, treated in a first settling tank, and coagulated by adding a coagulant FeCl 3 and a coagulant adjuvant polymer to precipitate and separate the suspended solids and CaCO 3 precipitates produced in the softening process. Adjusting the; Minimizing suspended solids in the wastewater and transferring the supernatant to a neutralization reactor by subjecting the wastewater completed to the flocculation reaction in a secondary sedimentation tank to secondary precipitation. The acid is added to the neutralization reaction tank to neutralize the acidity of the wastewater, and characterized in that the configuration comprising the step of transferring to the primary treatment water storage tank.
상기 연화반응단계에서는 Mg(OH)2의 침전 형성을 억제시킴과 동시에 CaSO4만을 효과적으로 제거하기 위하여 폐수의 산성도가 pH 10.4를 넘지 않도록 조절하고, 상기 중화단계에서는 폐수를 증발농축하는 후처리시에 CaCO3이 침전되는 것을 방지하기 위하여 폐수의 산성도를 pH 5~6으로 처리되게 한다.In the softening reaction step, the acidity of the wastewater is controlled not to exceed pH 10.4 in order to inhibit the precipitation formation of Mg (OH) 2 and to effectively remove CaSO 4 only. The acidity of the wastewater is treated with a pH of 5 to 6 to prevent the precipitation of CaCO 3 .
이하, 본 발명의 바람직한 실시 예를 첨부한 도면을 참조하면서 상세히 설명하기로 한다.Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
도 1은 본 발명에 의한 탈황/탈질폐수의 전처리 방법을 포함하는 전체 처리공정을 나타낸 블록 흐름도이고, 도 2는 본 발명에 의한 탈황/탈질폐수의 전처리 방법을 설명하기 위해 나타낸 공정도이다.Figure 1 is a block flow diagram showing the entire treatment process including the pre-treatment method of desulfurization / denitrification waste water according to the present invention, Figure 2 is a flow chart showing to explain the pretreatment method of desulfurization / denitrification waste water according to the present invention.
도 1에 나타낸 바와 같이, 본 발명에 의한 탈황/탈질폐수의 처리를 위한 전체 공정을 살펴보면, 탈황/탈질폐수의 부유물질을 물리적으로 침전시켜 제거함과 더불어 스케일형성 가능물질들을 연화 및 응집 처리하여 제거하고 중화 처리하는 전처리단계(S10)와; 상기 전처리단계(S10)를 마친 탈황/탈질폐수의 1차 처리수를 증발 농축하고 염분을 결정시켜 제거함과 아울러 응축하여 재사용 가능한 응축수를 생산하는 후처리단계(S20)로 이루어진다.As shown in Figure 1, when looking at the overall process for the treatment of the desulfurization / denitrification waste water according to the present invention, by removing the physically precipitated suspended solids of the desulfurization / denitrification waste water by removing the softening and flocculation of the scaleable substances And a pretreatment step (S10) for neutralization treatment; After the pre-treatment step (S10) of the desulfurization / denitrification waste water is evaporated and concentrated to determine the salinity and condensation is made of a post-treatment step (S20) to produce a reusable condensate.
상기 전처리단계(S10)는 응집 및 침전을 통해 폐수에서 부유물질을 극소화시키고 탄산나트륨(Na2CO3)을 이용한 비탄산경도 연화반응을 유도하여 황산칼슘(CaSO4) 농도를 극소화시키며 수산화칼슘 Ca(OH)2을 이용한 탄산경도 연화반응을 유도하여 중탄산칼슘 Ca(HCO3)2을 제거함으로써 폐수 중에 함유된 염의 성분들이 증발농축공정에서 스케일을 생성하지 않도록 하기 위한 것이다.The pretreatment step (S10) minimizes suspended solids in the wastewater through aggregation and precipitation, induces a non-acid hardening reaction using sodium carbonate (Na 2 CO 3 ) to minimize the concentration of calcium sulfate (CaSO 4 ), and calcium hydroxide Ca (OH). Carbonate hardness using 2 is to induce a softening reaction to remove calcium bicarbonate Ca (HCO 3 ) 2 so that the components of the salt contained in the wastewater do not produce scale in the evaporative concentration process.
더욱 상세하게, 상기 전처리단계(S10)는 도 2에 나타낸 바와 같이, 탈황/탈질폐수(원수) 저장조로부터 유입된 폐수를 1차침전조(1)에서 1차 침전 처리하여 폐수 중의 부유물질을 최대한 제거하고 상등수를 회수조(2)로 이송 처리한다(S11).More specifically, the pretreatment step (S10), as shown in Figure 2, the primary sedimentation treatment of the wastewater introduced from the desulfurization / denitrification wastewater (raw water) storage tank in the primary sedimentation tank (1) to remove the suspended matter in the wastewater as much as possible Then, the supernatant water is transferred to the recovery tank 2 (S11).
이때, 탈황/탈질폐수의 원수 중에는 부유물질이 20,000ppm 정도가 되고 용해물 중 CaSO4이 포화상태가 되어 2,000ppm 정도가 되고 Ca(HCO3)2이 대략 40ppm 정도가 되며 기타 용해고형물이 30,000ppm 정도가 함유되어 있다.At this time, in the raw water of desulfurization / denitrification waste water, suspended matter becomes about 20,000ppm, CaSO 4 becomes saturated in the melt, about 2,000ppm, Ca (HCO 3 ) 2 is about 40ppm, and other dissolved solids is 30,000ppm. It contains a degree.
상기 1차침전조(1)에서 처리를 한 상등수의 수질상태는 폐수의 원수에 비해 부유물질은 1,500ppm 정도이고 CaSO4은 2,000ppm 정도이고 Ca(HCO3)2이 40ppm 정도이며 기타 용해고형물이 30,000ppm의 상태가 된다.The primary water quality conditions of the process the supernatant from the settling tank (1) is suspended solids than raw water of the waste water is about 1,500ppm, and CaSO 4 are about 2,000ppm, and Ca (HCO 3) 2 is about 40ppm, and other dissolved solids 30,000 It becomes the state of ppm.
상기 회수조(2)에 저장된 상등수를 연화반응조(3)로 유입되게 하고 상기 연화반응조(3)에 Na2CO3과 Ca(OH)2의 연화제를 동시 투입하여 폐수 중에서 CaSO4와 Ca(HCO3)2의 각각을 CaCO3로 침전시켜 제거되게 한다(S12).The supernatant stored in the recovery tank (2) is introduced into the softening reaction tank (3), and the softening reaction of Na 2 CO 3 and Ca (OH) 2 is simultaneously added to the softening reaction tank (3) to remove CaSO 4 and Ca (HCO) from the wastewater. 3 ) Each of 2 is precipitated with CaCO 3 to be removed (S12).
이때, 상기 연화반응조(3) 내에서 탈황/탈질폐수 내에 함유된 CaSO4와 Ca(HCO3)2의 제거를 위한 각각의 반응관계를 설명하면 다음의 [화학식3] 및 [화학식4]와 같다.At this time, the respective reaction relationship for the removal of CaSO 4 and Ca (HCO 3 ) 2 contained in the desulfurization / denitrification waste water in the softening reaction tank (3) is as follows [Formula 3] and [Formula 4] .
[화학식3][Formula 3]
CaSO4 + Na2CO3 = Na2SO4 + CaCO3CaSO 4 + Na 2 CO 3 = Na 2 SO 4 + CaCO 3
[화학식4][Formula 4]
Ca(HCO3)2 + Ca(OH)2 = 2CaCO3↓ + 2H2OCa (HCO 3 ) 2 + Ca (OH) 2 = 2CaCO 3 ↓ + 2H 2 O
또한, 상기 연화반응과정(S13)에서는 상기 [화학식3]의 반응과정에서 수산화마그네슘{Mg(OH)2}의 침전 형성을 억제시킴과 동시에 CaSO4만을 효과적으로 제거하기 위하여 상기 연화반응조(3) 내 산성도(pH)가 10.4를 넘지 않도록 한다. 이러한 pH의 조절은 폐수 중에서 Mg(OH)2의 침전이 pH 10.7에서부터 발생하기 때문에 스케일 형성방지 및 수질개선을 위해 필수적으로 요구된다.In addition, in the softening reaction step (S13) in the reaction process of [Formula 3] to suppress the precipitate formation of magnesium hydroxide {Mg (OH) 2 } and at the same time to effectively remove only CaSO 4 in the softening reaction tank (3) The acidity (pH) should not exceed 10.4. This adjustment of pH is essential for the prevention of scale formation and the improvement of water quality since precipitation of Mg (OH) 2 occurs in the wastewater from pH 10.7.
상기 연화반응조(3)에서 연화반응에 의해 생성된 CaCO3 침전물을 포함하는 폐수를 응집반응조(4)로 유입되게 하고 상기 응집반응조(4)에 응집제인 FeCl3와 응집보조제인 폴리머(polymer)를 투입하여 폐수 내에서 CaCO3 침전물들의 분리를 용이하게 하되 응집 침전되게 한다(S13).In the softening reaction tank (3), the wastewater containing CaCO 3 precipitates produced by the softening reaction is introduced into the coagulation reaction tank (4), and FeCl 3 and a coagulation aid polymer are added to the coagulation reaction tank (4). To facilitate the separation of CaCO 3 sediments in the wastewater, but to precipitate flocculation (S13).
이때, 상기 응집반응조(4) 내에서의 응집반응관계를 설명하면 다음의 [화학식5]와 같다.In this case, the coagulation reaction relationship in the coagulation reaction tank 4 will be described with the following [Formula 5].
[화학식5][Formula 5]
2FeCl3 + 3Ca(HCO3)2 = 2Fe(OH)3↓ + 6CO2 2FeCl 3 + 3Ca (HCO 3 ) 2 = 2Fe (OH) 3 ↓ + 6CO 2
즉, 연화반응에서 생성된 CaCO3이 분리되어 응집 침전되고 Fe(OH)3의 침전물을 형성하면서 다른 침전물들을 흡착하여 침전하기에 좋도록 보다 큰 응집 침전물을 생성하게 된다.That is, CaCO 3 produced in the softening reaction is separated and coagulated and precipitated to form a precipitate of Fe (OH) 3 to generate a larger flocculated precipitate to be good to adsorb other precipitates.
여기서, 상기 응집반응 후의 폐수 수질은 부유물질이 1,500ppm 정도이고 폐수의 증발농축공정시 스케일 생성요인이 되는 CaSO4와 Ca(HCO3)2이 거의 제거되며 기타 용해고형물이 30,000ppm 정도가 된다.Herein, the wastewater quality after the flocculation reaction is about 1,500 ppm of suspended solids, and CaSO 4 and Ca (HCO 3 ) 2, which are scale generation factors in the evaporative concentration process of the waste water, are almost eliminated, and other dissolved solids are about 30,000 ppm.
상기 응집반응과정(S13)까지 마친 폐수를 2차침전조(5)에서 2차 침전 처리하여 폐수 중에서 부유물질을 극소화시키고 상등수를 중화반응조(6)로 이송 처리한다(S14).The wastewater finished up to the flocculation reaction process (S13) is subjected to the second precipitation treatment in the secondary settling tank (5) to minimize suspended solids in the wastewater and transfer the supernatant water to the neutralization reaction tank (S14).
이때, 상기 2차 침전 처리에 의한 상등수의 수질상태는 부유물질이 20ppm 이하로 되고, 기타 용해고형물이 30,000ppm 정도가 되며, pH가 10.4 정도를 유지하게 된다.At this time, the water quality of the supernatant water by the secondary precipitation treatment is less than 20ppm suspended solids, other dissolved solids is about 30,000ppm, the pH is maintained at about 10.4.
상기 중화반응조(6)로 이송 처리된 폐수는 중화반응조(6)에 HCl 등의 산을 투입하여 10.4의 pH를 5~6으로 중화 처리하고 1차 처리수저장조(7)로 이송 처리한다(S15).Wastewater transferred to the neutralization reaction tank (6) is neutralized with a pH of 10.4 to 5 to 6 by adding an acid such as HCl to the neutralization reaction vessel (6) and transported to the primary treatment water storage tank (S15). ).
여기서, 상기 pH를 5~6의 범주로 중화 처리하는 이유는 후처리단계(S20)의 증발농축과정에서 스케일 형성요인이 되는 CaCO3이 침전되는 것을 방지하기 위함이다. 즉, 수질처리지수인 LSI(Langelia Sturated Index) 계산에서 적용 pH가 높으면 LSI가 0보다 커져 스케일 형성 가능성이 높아지기 때문에 LSI를 0보다 낮게 하기 위하여 중화처리가 필요하게 되는 것이다.The reason for neutralizing the pH in the range of 5 to 6 is to prevent precipitation of CaCO 3, which is a factor of scale formation, in the evaporative concentration process of the post-treatment step (S20). In other words, when the applied pH is high in the Langel (Langelia Sturated Index) calculation, which is a water treatment index, since the LSI becomes larger than zero, the possibility of scale formation is increased, so that neutralization treatment is required to make the LSI lower than zero.
이때, 상기 중화과정(S15)까지 마친 폐수의 수질상태는 부유물질이 20ppm 이하로 되고, 기타 용해고형물이 30,000ppm 정도가 되며, pH 5~6을 유지하게 된다.At this time, the water quality of the wastewater completed by the neutralization process (S15) is less than 20ppm suspended solids, other dissolved solids is about 30,000ppm, and maintains the pH 5-6.
아울러, 상기 중화과정(S15)에 의한 폐수의 중화 처리시에 폐수의 pH가 7이하로 조절됨에 따라 폐수 중에 함유된 질소산화물이 휘발되지 않는 특성을 발휘하게 된다.In addition, as the pH of the wastewater is adjusted to 7 or less during the neutralization of the wastewater by the neutralization process (S15), the nitrogen oxides contained in the wastewater are not volatilized.
나아가, 상기 1차침전조(1)에서 생성되는 슬러지와 상기 2차침전조(5)에서 생성되는 슬러지는 농축조(8)로 이송하여 농축 처리하며, 상기 농축조(8)에서의 상등 수는 상기 회수조(2)로 회수 처리하고 농축슬러지는 탈수기(9)를 통해 탈수 처리한다(S16).Furthermore, the sludge produced in the primary sedimentation tank 1 and the sludge produced in the secondary sedimentation tank 5 are transferred to the concentration tank 8 for concentration processing, and the supernatant water in the concentration tank 8 is the recovery tank. Recovered to (2) and the concentrated sludge is dewatered through a dehydrator (9) (S16).
이때, 상기 농축조(8)에는 폴리머를 투입하여 슬러지가 응집되면서 농축되게 한다.At this time, the concentration of the sludge is concentrated by injecting a polymer into the concentration tank (8).
상기 후처리단계(S20)는 상기 1차 처리수저장조(7)로부터 전처리된 1차 처리수를 진공증발농축기(10)에서 증발농축하고 결정화장치(11)를 통해 보다 더 농축(S21)시키며, 증발농축과정(S21)에서의 증발증기는 응축기(12)를 통해 응축수 처 리하여 재사용할 수 있게 한다(S22).The post-treatment step (S20) evaporates and concentrates the primary treated water pretreated from the primary treated water storage tank (7) in a vacuum evaporator (10) and further concentrates (S21) through a crystallization apparatus (11), The evaporation vapor in the evaporation concentration process (S21) allows the condensate to be processed and reused through the condenser 12 (S22).
이때, 상기 전처리(S10)에 의해 1차 처리수의 수질상태가 매우 안정되고 스케일 형성요인이 모두 사전에 제거됨에 따라 1차 처리수가 고농도로 증발농축되면서 스케일을 발생하지 않게 되어 증발농축설비의 효율저하를 예방하게 됨은 물론 상기 증발농축과정(S21)에서 1차 처리수에 함유되어 있던 질소산화물이 증발증기가 아닌 농축액으로 배출 처리되므로 응축기(12)로 유입되지 않아 양질의 응축수가 생산되는 것이다.At this time, the water quality of the primary treated water is very stable by the pretreatment (S10), and the scale forming factors are all removed in advance, so that the primary treated water is evaporated and concentrated at a high concentration so that the scale is not generated. In addition to preventing degradation, the nitrogen oxide contained in the first treatment water in the evaporation concentration process (S21) is discharged as a concentrate rather than an evaporation vapor, so that the condensate 12 does not flow into the condenser 12, thereby producing high quality condensate.
여기서, 상기 응축기(12)를 통과한 응축수의 수질은 전처리를 효율화함에 따라 전도도(conductivity)가 150μS, 총 경도(2가 금속이온의 총량을 탄산칼슘량으로 환산한 것으로 물의 경도를 나타내는 수치가 단물(0~75ppm)에 해당하는 50ppm 이하, Cl-이온이 40ppm 이하, TDS(Total Dissolved Solid; 총용존 고형물질)이 수돗물(40~100ppm)에 해당하는 70ppm 이하, COD(화학적 산소 요구량)가 3ppm 이하로 재사용이 가능한 양질의 수질상태를 형성하게 된다.Here, the water quality of the condensed water passing through the condenser 12 has a conductivity of 150 μS as the efficiency of pretreatment and a total hardness (the total hardness of the divalent metal ions is converted into the amount of calcium carbonate. 50 ppm or less (0 to 75 ppm), Cl - ion is 40 ppm or less, TDS (Total Dissolved Solid) is 70 ppm or less for tap water (40 to 100 ppm), COD (chemical oxygen demand) 3 ppm It will form a high quality water quality that can be reused below.
또한, 상기 결정화장치(11)에서의 농축액은 상기 탈수기(9)로 보내 탈수 처리하고 케이크(cake) 상태로 배출시킨다(S23).In addition, the concentrated liquid in the crystallization apparatus 11 is sent to the dehydrator 9 to be dehydrated and discharged in a cake state (S23).
이상에서 살펴본 바와 같이 본 발명에 의한 탈황/탈질폐수의 전처리 방법에 의하면, 탈황/탈질폐수로부터 부유물질을 극소화할 수 있고 스케일 형성요인이 되 는 용해물을 최적의 조건으로 사전 제거할 수 있게 하며 전처리 효율의 향상으로 전처리된 수질상태를 매우 안정되게 하므로 탈황/탈질폐수 중에 함유된 염(鹽)성분들이 후처리의 증발농축공정시에 스케일을 발생하지 않고 고농도로 증발농축될 수 있도록 증발농축설비에 공급할 수 있게 한다.As described above, according to the method for pretreatment of desulfurization / denitrification wastewater according to the present invention, it is possible to minimize suspended solids from the desulfurization / denitrification wastewater and to remove the dissolved substance which is a factor of scale in advance under optimum conditions. The evaporation concentration facility is designed to make the pre-treated water quality very stable by improving the pretreatment efficiency, so that the salt components contained in the desulfurization / denitrification waste water can be evaporated to high concentration without generating scale during the evaporation concentration process of the post-treatment. To be supplied.
이에 따라 증발농축설비의 효율저하를 예방하는 유용함을 발휘하며, 증발농축공정에서 생산되는 응축수의 수질을 매우 양호하게 할 수 있음은 물론 생산되는 응축수를 재사용할 수 있게 하는 아주 커다란 유용성을 발휘되게 하며, 탈황/탈질폐수에 의한 환경오염문제를 개선할 수 있게 한다.As a result, it is useful for preventing the deterioration of the efficiency of the evaporation concentrating equipment, and the quality of condensate produced in the evaporation concentrating process can be made very good, and the condensate produced can be reused. It also helps to improve the environmental pollution problem caused by desulfurization / denitrification wastewater.

Claims (2)

  1. 탈황/탈질폐수의 처리를 위한 전처리 방법에 있어서,In the pretreatment method for the treatment of desulfurization / denitrification wastewater,
    탈황/탈질폐수의 원수저장조로부터 유입된 폐수를 1차침전조에서 1차 침전 처리하여 폐수 중의 부유물질을 최대한 제거하고 상등수를 회수조로 이송 처리하는 단계와;Treating the wastewater introduced from the desulfurization / denitrification wastewater storage tank with primary sedimentation in the primary sedimentation tank to remove the suspended solids in the wastewater as much as possible and transferring the supernatant to the recovery tank;
    상기 회수조에 저장된 상등수를 연화반응조로 유입되게 하고 상기 연화반응조에 Na2CO3과 Ca(OH)2의 연화제를 투입하여 폐수 중에 함유된 CaSO4와 Ca(HCO3)2의 각각을 CaCO3로 침전시켜 제거하는 단계와;The supernatant stored in the recovery tank was introduced into a softening reactor, and a softener of Na 2 CO 3 and Ca (OH) 2 was added to the softening reactor to convert CaSO 4 and Ca (HCO 3 ) 2 contained in the wastewater into CaCO 3 . Precipitating and removing;
    상기 연화반응을 마친 폐수를 응집반응조로 유입시켜 1차침전조에서 처리하고 잔류된 부유물과 연화공정에서 생성된 CaCO3 침전물들을 침전 분리하기 위해 응집제인 FeCl3와 응집보조제인 폴리머를 투입하여 응집시키며 산성도를 조절하는 단계와;The wastewater after the softening reaction is introduced into a coagulation tank, treated in a first settling tank, and coagulated by adding FeCl 3 and a coagulant polymer in order to precipitate and separate the suspended matter and CaCO 3 precipitates generated in the softening process. Adjusting the;
    상기 응집반응까지 마친 폐수를 2차침전조에서 2차 침전 처리하여 폐수 중에서 부유물질을 극소화시키고 상등수를 중화반응조로 이송시키는 단계와;Minimizing suspended solids in the wastewater and transferring the supernatant to a neutralization reactor by subjecting the wastewater completed to the flocculation reaction in a secondary sedimentation tank to secondary precipitation.
    상기 중화반응조에 산을 투입하여 폐수의 산성도를 중화 처리하고 1차 처리수저장조로 이송시키는 단계를 포함하여 이루어지는 것을 특징으로 하는 탈황/탈질폐수의 전처리 방법.A method for pretreatment of desulfurization / denitrification wastewater, comprising the step of neutralizing the acidity of the wastewater by adding acid to the neutralization reaction tank and transferring the acidity to the primary treatment water storage tank.
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KR101054036B1 (en) * 2008-07-09 2011-08-03 주식회사 세화엔스텍 Descaling Method of Evaporative Concentrator for Desulfurization Wastewater Treatment
CN106854020B (en) * 2015-12-09 2020-02-14 中国石油天然气股份有限公司 Method for recycling sulfur-containing gas production wastewater
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CN105502792A (en) * 2016-01-27 2016-04-20 成都锐思环保技术股份有限公司 Zero-discharge treatment method of desulfurization waste water
CN105523677A (en) * 2016-01-27 2016-04-27 成都锐思环保技术股份有限公司 Treatment system capable of realizing zero discharge of desulfurization wastewater
CN105502540A (en) * 2016-01-27 2016-04-20 成都锐思环保技术股份有限公司 Anti-scaling and anti-corrosion desulfurization waste water multi-effect evaporation, concentration and crystallization method
WO2017133513A1 (en) * 2016-02-05 2017-08-10 大唐环境产业集团股份有限公司 Treatment apparatus and method for softening desulfurization wastewater
WO2017133514A1 (en) * 2016-02-05 2017-08-10 大唐环境产业集团股份有限公司 Treatment apparatus and method for softening desulfurization wastewater
CN105692959A (en) * 2016-03-01 2016-06-22 大唐环境产业集团股份有限公司 Low-sludge-output desulfurization waste water treatment device and method

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