CN215249603U - Coal fired power plant desulfurization waste water recycling system - Google Patents

Abstract

The utility model discloses a coal fired power plant desulfurization waste water resource system, this resource system includes the waste water desulfurization pipeline: sequentially passes through a first-stage sedimentation tank, a first pressure filter, a second-stage sedimentation tank, a second pressure filter, a stirring tank, an acidification reaction tower, a third pressure filter, a first-stage purification tank, a fourth pressure filter, a second-stage purification tank, a fifth pressure filter and a clear waterSink, sixth pressure filter and Mg (OH)₂A drying pool; a wastewater desulfurization branch: sequentially passing through CaCl from a fifth filter press₂Concentrating column and CaCl₂A drying pool; a return line: connecting the first-stage purification tank with CaCl₂A concentration tower; the tower wall of the acidification reaction tower is provided with an air inlet, the tower top is provided with an air outlet, the air inlet is communicated with clean flue gas through a pipeline, and the air outlet is connected with the absorption tower through a pipeline. The utility model discloses can purify out high-purity Mg (OH) from waste water₂、CaCl₂And (3) after the finished product is obtained, the rest ion components and water in the wastewater are all returned to the desulfurization system for recycling, so that the resource utilization rate of the desulfurization wastewater is improved.

Description

Coal fired power plant desulfurization waste water recycling system

Technical Field

The utility model relates to a coal fired power plant's desulfurization waste water treatment especially relates to a coal fired power plant's desulfurization waste water resource system.

Background

When the coal-fired generator set is in operation, sulfur contained in the coal reacts with oxygen in the air to form SO when the coal is combusted₂、SO₃Gas, which is mixed in the flue gas at the outlet of the combustion boiler. According to the requirement of environmental protection, SO contained in the flue gas is removed by a desulfurization system needing to be put into operation₂、SO₃Gas to achieve the purpose of removing sulfur; the common system for flue gas desulfurization is limestone wet desulfurization, which adopts pulverized limestone as a reaction raw material. Limestone mainly comprises CaCO₃And MgCO₃Mixing with water to obtain limestone slurry, and mixing with SO in flue gas in desulfurizing absorption tower₂、SO₃Gas reaction is carried out, and insoluble matters of calcium sulfate and calcium sulfite are generated in an acid environment of the absorption tower; during the reaction process, Ca and Mg elements in the limestone are completely dissolved into Ca in the absorption tower²⁺、Mg²⁺And the concentration of the ions gradually increases to nearly 7000mg/L in the concentration process of the absorption tower, and finally flows out along with the desulfurization waste water discharged by the absorption tower.

When the coal-fired power generating unit is used for treating desulfurization wastewater, the wastewater is firstly concentrated, and Mg in the concentrated high-concentration wastewater solution²⁺The ion concentration can reach more than 60000Mg/L, but the Mg is partially added in the subsequent treatment²⁺The waste is mixed into fly ash or gypsum for low-quality treatment, and the treated fly ash or gypsum has low market value. In the concentrated wastewater treatment process, a large amount of energy is consumed, more equipment is occupied for treatment, the treatment cost is high, and the waste of a large amount of Mg element with high market value in the solution is caused.

The root cause of the unavailability of desulfurization waste water of coal-fired power generating units is Cl contained therein^-Ions. Cl in absorption tower of desulfurization system^-The existence of ions can cause the problems of low desulfurization efficiency, equipment corrosion and the like, and the absorption tower is required to discharge desulfurization wastewater outwards and supplement freshWater to reduce Cl in the absorber^-The concentration of the ions. During dechlorination, sodium chloride is usually prepared by adding sodium carbonate. However, the operation cost is obviously increased due to high sodium carbonate cost and low sodium chloride selling price, the whole operation benefit of an enterprise is reduced when the zero discharge is carried out in a coal-fired power plant, the popularization and the application of the zero discharge of the wastewater of the coal-fired power generating unit are not facilitated, and the resource utilization rate is low.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a coal fired power plant desulfurization waste water resource system is provided, this resource system can carry out make full use of to the high value particle in the waste water to improve desulfurization waste water's utilization ratio.

Solve above-mentioned technical problem, the utility model discloses the technical scheme who adopts as follows:

the utility model provides a coal fired power plant desulfurization waste water resource system which characterized in that includes:

a wastewater desulfurization pipeline: sequentially passes through a primary sedimentation tank, a first pressure filter, a secondary sedimentation tank, a second pressure filter, a stirring tank, an acidification reaction tower, a third pressure filter, a primary purification tank, a fourth pressure filter, a secondary purification tank, a fifth pressure filter, a cleaning tank, a sixth pressure filter and Mg (OH)₂A drying pool;

a wastewater desulfurization branch: sequentially passing through CaCl from a fifth filter press₂Concentrating column and CaCl₂A drying pool;

a return line: connecting the first-stage purification tank with CaCl₂A concentration tower;

the tower wall of the acidification reaction tower is provided with an air inlet, the tower top is provided with an air outlet, the air inlet is filled with clean flue gas through a pipeline, and the air outlet is connected with the absorption tower through a pipeline;

the first pressure filter, the third pressure filter and the sixth pressure filter are all provided with insoluble substance discharge ports;

the second pressure filter and the fifth pressure filter are both provided with solution discharge ports, and the solution discharge port of the fifth pressure filter is communicated with the CaCl through a pipeline₂The concentration tower is connected.

The insoluble substance discharge port of the sixth filter press is connected with the absorption tower through a pipeline.

The utility model discloses Mg (OH)₂A drying tank and said CaCl₂The discharge ports of the drying pools are provided with conveying devices for conveying the dried objects.

The one-level sedimentation tank the second grade sedimentation tank one-level purification pond with the top in second grade purification pond all is equipped with the medicine mouth.

Compared with the prior art, the utility model discloses the technique has following advantage:

the utility model discloses a coal fired power plant desulfurization waste water resource system utilizes the characteristics of ion composition in the desulfurization waste water, and the high concentration waste water after will concentrating is through one-level deposit, second grade deposit, acidizing, one-level purification, second grade purification and washing purification treatment back, can follow and purify out high-purity Mg (OH) in the desulfurization waste water₂、CaCl₂And (3) finished products, namely all the rest ionic components and water in the desulfurization wastewater flow back to the desulfurization system for recycling, so that the resource utilization rate of the desulfurization wastewater is improved.

Drawings

The invention will be described in detail with reference to the drawings and specific embodiments

FIG. 1 is the schematic diagram of the desulfurization waste water recycling system of coal-fired power plant.

Reference numbers on the drawings: 1-first-stage sedimentation tank, 2-first pressure filter, 3-second-stage sedimentation tank, 4-second pressure filter, 5-stirring tank, 6-acidification reaction tower, 7-third pressure filter, 8-first-stage purification tank, 9-fourth pressure filter, 10-second-stage purification tank, 11-fifth pressure filter, 12-cleaning tank, 13-sixth pressure filter, 14-Mg (OH)₂Drying pool, 15-Mg (OH)₂Conveying device, 16-CaCl₂Concentration tower, 17-CaCl₂Drying tank, 18-CaCl₂Delivery device, 19-return line.

Detailed Description

Referring to fig. 1, the embodiment of the system for recycling desulfurization wastewater of coal-fired power plant of the present invention comprises:

a wastewater desulfurization pipeline: sequentially goes through the first-stage sedimentationA sedimentation tank 1, a first pressure filter 2, a secondary sedimentation tank 3, a second pressure filter 4, a stirring tank 5, an acidification reaction tower 6, a third pressure filter 7, a primary purification tank 8, a fourth pressure filter 9, a secondary purification tank 10, a fifth pressure filter 11, a cleaning tank 12, a sixth pressure filter 13 and Mg (OH)₂A drying tank 14;

a wastewater desulfurization branch: passing through CaCl from the fifth filter press 11 in sequence₂Concentrating column 16 and CaCl₂ A drying tank 17;

return line 19: connecting the first-stage purification tank 8 and CaCl₂ A concentration column 16;

the tower wall of the acidification reaction tower 6 is provided with an air inlet, the tower top is provided with an air outlet, the air inlet is filled with clean flue gas through a pipeline, and the air outlet is connected with the absorption tower through a pipeline;

the first pressure filter 2, the third pressure filter 7 and the sixth pressure filter 13 are all provided with insoluble matter discharge ports;

the second pressure filter 4 and the fifth pressure filter 11 are each provided with a solution discharge port.

The insoluble matter discharge port of the sixth pressure filter 13 in this example is connected to the absorption column through a pipe.

In this example, Mg (OH)₂The discharge port of the drying pond 14 is provided with Mg (OH)₂Conveying means 15, CaCl₂The discharge port of the drying tank 17 is provided with CaCl₂A conveyor 18.

The top of the first-stage sedimentation tank 1, the second-stage sedimentation tank 3, the first-stage purification tank 8 and the second-stage purification tank 10 in the embodiment are all provided with a dosing port.

The method for recycling desulfurization wastewater of the coal-fired power plant in the embodiment comprises the following steps:

(1) the concentrated desulfurization wastewater of the coal-fired power plant enters a primary sedimentation tank 1 and is added with Ca (OH) in the primary sedimentation tank 1₂The solution reacts in a weakly acidic environment with the pH value controlled to be 2-5 to generate CaSO₄The precipitate is discharged out of the pipeline after being filtered by the first pressure filter 2, and the solution after being filtered by pressure enters a secondary sedimentation tank 3;

(2) the solution after filter pressing and Ca (OH) added in a secondary sedimentation tank 3₂The reaction is carried out in an alkaline environment with the pH value of the solution controlled to be 11-12CaSO produced₄And Mg (OH)₂The precipitated mixture is filtered and pressed by a second filter press 4 and then enters a stirring tank 5, and the filtered solution is discharged from a pipeline and is separately collected to purify CaCl₂；

(3) Clear water and CaSO are added into the stirring pool 5₄And Mg (OH)₂Stirring the precipitate mixture into slurry, and feeding the precipitate mixed slurry into an acidification reaction tower 6;

(4) introducing clean flue gas from an air inlet of the acidification reaction tower 6, wherein the clean flue gas contains SO₃And SO₂After the clean flue gas and the precipitate mixed slurry react, controlling the pH value of the precipitate mixed slurry after the reaction with the clean flue gas to be 2-3, discharging the slurry from an air outlet of an acidification reaction tower 6, conveying the slurry into an absorption tower, and adding Mg (OH) in the precipitate mixed slurry₂Dissolve to form Mg²⁺Ionic solution, CaSO filtered by the third filter press 7₄Discharging the precipitate out of the pipeline, and feeding the solution after filter pressing into a primary purification tank 8;

(5) the solution after filter pressing and CaCl added in a primary purification tank 8₂The solution reacts to generate precipitate CaSO₄The solution is filtered out by a fourth filter press 9 and becomes gypsum and then is discharged out of a pipeline, and the solution after filter pressing enters a secondary purification tank 10; controlling the pH value of the solution after the primary purification to be 11-12;

(6) the solution after pressure filtration is mixed with Ca (OH) added in the secondary purification tank 10₂The solution is reacted to produce Mg (OH)₂The precipitate was pressure-filtered through a fifth pressure filter 11 to be in the form of a paste (Mg (OH) therein)₂The purity is close to 97 percent) and enters a clean water tank 12, the solution after filter pressing enters a wastewater desulfurization branch from a solution discharge port of a fifth filter press 11 and flows to CaCl₂In the concentration tower 16;

(7) adding clear water and paste Mg (OH) into the clear water tank 12₂In (1) CaCl₂Dissolved in clear water to form a paste Mg (OH)₂Cleaning and purifying, cleaning and purifying Mg (OH)₂Filter-pressed through a sixth filter press 13 into Mg (OH)₂ Drying tank 14, Mg (OH) in dried solid matter₂The purity reaches 99 percent, the finished product is packaged by a conveying device 15, and the solution after filter pressing is conveyed to a suction deviceCollecting the tower;

into CaCl₂The solution of the concentration tower 16 is passed through CaCl₂Concentrating in a concentrating tower 16 to obtain part of concentrated CaCl₂Reflowing to the first-stage purification tank 8 through a reflow line 19 for supplementary reaction, and concentrating the other part of the CaCl₂Into CaCl₂A drying tank 17;

(8)Mg(OH)₂ drying pool 14 Pair paste Mg (OH)₂Drying to obtain Mg (OH) with purity of over 90%₂Finished product and passing through Mg (OH)₂The conveying device 15 conveys the materials to packaging equipment for packaging;

CaCl₂drying pool 17 for concentrated CaCl₂Drying to obtain CaCl₂The finished product is passed through CaCl₂The conveyor 18 feeds the packaging plant for packaging.

The utility model discloses utilize the characteristics of ionic composition in the desulfurization waste water, with the high concentration waste water after the concentration through one-level deposit, second grade deposit, acidizing, one-level purification, second grade purification and wash purification treatment after, can purify out high-purity Mg (OH) from desulfurization waste water₂、CaCl₂Final product, in which Mg (OH)₂The purity of the finished product reaches 99 percent, and CaCl₂The purity of the finished product reaches 90%, and the rest ionic components and water in the desulfurization wastewater completely flow back to the desulfurization system for recycling, so that the resource utilization rate of the desulfurization wastewater is improved.

The utility model discloses a process principle: first, Na in the desulfurization waste water is reduced⁺、Cl^-The total amount of ions, the regeneration of cation resin adopts sulfuric acid instead of hydrochloric acid, and the main ionic component is Na by the waste water generated in the fine treatment of a coal-fired power generating set and the resin regeneration of a water preparation system⁺、SO₄ ^2-Separately concentrating the part of wastewater to purify high-purity finished product Na₂SO₄Producing a product;

secondly, after preheating and concentrating the low-sodium desulfurization wastewater by using flue gas, firstly performing a purification process of magnesium hydroxide, wherein the purification process of the magnesium hydroxide comprises primary precipitation, secondary precipitation, acidification, primary purification, secondary purification and cleaning purification, and then purifying high-purity magnesium hydroxide;

finally, the main ionic component in the solution after the secondary precipitation is Ca²⁺、Cl^-The solution is dried and then high-purity CaCl is purified₂And (5) producing the product.

Through the 3 steps, the desulfurization wastewater generated by the coal-fired power generating unit can be completely recycled, and the problems of waste and coal ash doping are solved.

The more specific steps are as follows:

1. independent treatment of sodium from resin regeneration of coal-fired power generating units

1) The regeneration of the cation resin adopts sulfuric acid regeneration, avoids adopting hydrochloric acid regeneration, and reduces Cl^--Total amount of ions that may enter the system;

2) separately treating waste water generated by regeneration of anion and cation resin, wherein the main ionic component is Na⁺、SO₄ ^2-The wastewater is concentrated into high-concentration Na by adopting a medium-temperature air concentration mode₂SO₄A solution;

3) conveying the high-concentration solution to a dryer for drying to obtain a finished product Na₂SO₄Producing a product;

2. purification of magnesium hydroxide from desulfurized waste water

Using mainly Mg²⁺Ion and Ca²⁺The difference of the characteristics of the precipitates is taken as a starting point, and the concentrated high-concentration wastewater is subjected to 6 processes of primary precipitation, secondary precipitation, acidification, primary purification, secondary purification, cleaning and purification and the like to produce Mg (OH) with the purity of more than 99 percent₂A solid product;

1) primary precipitation: adding hydrated lime into concentrated strong-acid wastewater, adjusting the pH value of the solution to 2-5 weak acidity, and precipitating partial CaSO₄Precipitating a product and performing filter pressing to separate out the product;

2) secondary precipitation: adding hydrated lime into the solution after the first-stage precipitation, adjusting the pH value of the solution to 11-12, wherein the precipitation product in the solution is CaSO₄、Mg(OH)₂Solid, filter pressing to obtain the partial solid; separately collecting the solution and purifying calcium chloride;

3) acidifying: pressure of the secondary precipitationAdding clear water into the filtered solid product, stirring into slurry, and utilizing SO in the tail flue gas of the boiler₃、SO₂Gas, adjusting the pH of the solution to 2, precipitating Mg (OH) in the product₂Dissolve to form Mg with high concentration²⁺An ionic solution;

4) primary purification: adding CaCl into the acidified strong acid solution₂The SO in the solution₄ ^2-、SO₃ ^2-Precipitating ions and filtering out the ions by pressure;

5) secondary purification: adding slaked lime to the first-stage purified and filter-pressed solution to adjust the pH of the solution to 11 and precipitate a high purity Mg (OH)₂Concentrating and reducing water of the solid and the solution after filter pressing, and then entering a first-stage purification reaction stage;

6) cleaning and purifying: secondary purified Mg (OH)₂The solid has high water content and contains more dissolved CaCl₂Adding water into the solid for cleaning, and dissolving CaCl in the solid₂Washed off and filter-pressed again to give Mg (OH) of high purity₂A solid product;

3. purification of calcium chloride from magnesium hydroxide purified solution

The main ion component in the solution generated after the secondary precipitation in the magnesium hydroxide purification process is Ca²⁺、Cl^-The concentration of other ions is extremely low;

1) the wastewater is concentrated into high-concentration CaCl by adopting a high-temperature air concentration mode₂A solution;

2)CaCl₂conveying the solution to a dryer for drying to obtain finished CaCl₂And (5) producing the product.

The utility model discloses an adopt the mode of handling resin regeneration waste water and desulfurization waste water respectively, utilize the characteristics of ionic composition component in two kinds of waste water, purify out high-purity Mg (OH) with two kinds of waste water respectively₂、CaCl₂And (3) the chloride ions in the wastewater are completely recycled, and the residual ion components and water can be completely recycled to a desulfurization system, so that the complete recycling of the wastewater of the coal-fired generator set is completely realized.

The above embodiments of the present invention are not right the utility model discloses the limited protection scope, the utility model discloses an embodiment is not limited to this, all kinds of basis according to the above-mentioned of the utility model discloses an under the above-mentioned basic technical thought prerequisite of the utility model, right according to ordinary technical knowledge and the conventional means in this field the modification, replacement or the change of other multiple forms that above-mentioned structure made all should fall within the protection scope of the utility model.

Claims (4)

1. The utility model provides a coal fired power plant desulfurization waste water resource system which characterized in that includes:

a wastewater desulfurization pipeline: sequentially passes through a primary sedimentation tank, a first pressure filter, a secondary sedimentation tank, a second pressure filter, a stirring tank, an acidification reaction tower, a third pressure filter, a primary purification tank, a fourth pressure filter, a secondary purification tank, a fifth pressure filter, a cleaning tank, a sixth pressure filter and Mg (OH)₂A drying pool;

a wastewater desulfurization branch: sequentially passing through CaCl from a fifth filter press₂Concentrating column and CaCl₂A drying pool;

a return line: connecting the first-stage purification tank with CaCl₂A concentration tower;

the tower wall of the acidification reaction tower is provided with an air inlet, the tower top is provided with an air outlet, the air inlet is filled with clean flue gas through a pipeline, and the air outlet is connected with the absorption tower through a pipeline;

the first pressure filter, the third pressure filter and the sixth pressure filter are all provided with insoluble substance discharge ports;

the second pressure filter and the fifth pressure filter are both provided with solution discharge ports, and the solution discharge port of the fifth pressure filter is communicated with the CaCl through a pipeline₂The concentration tower is connected.

2. The system for recycling desulfurization wastewater from a coal-fired power plant according to claim 1, wherein the insoluble matter discharge port of the sixth pressure filter is connected to the absorption tower through a pipe.

3. The desulfurization wastewater for coal-fired power plants as defined in claim 2A recycling system, wherein the Mg (OH)₂A drying tank and said CaCl₂The discharge ports of the drying pools are provided with conveying devices for conveying the dried objects.

4. The desulfurization wastewater recycling system for coal-fired power plants as claimed in claim 3, wherein the top of the primary sedimentation tank, the top of the secondary sedimentation tank, the top of the primary purification tank and the top of the secondary purification tank are all provided with a dosing port.

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