阅读说明：本技术 一种脱硫废水处理系统和方法 (Desulfurization wastewater treatment system and method ) 是由 陆明智 孟涛 荆黎 陈智 杨洋 葛智泉 李建 叶明君 于 2021-07-13 设计创作，主要内容包括：本发明公开了一种脱硫废水处理系统及方法,所述系统包括除尘器、湿法脱硫吸收塔、废水收集池、浓缩塔、调节沉淀装置、蒸发结晶器；除尘器与湿法脱硫吸收塔通过烟气管道连通；湿法脱硫吸收塔的出水口连通废水收集池,废水收集池的出水口连通浓缩塔的入水口,浓缩塔的出水口连通调节沉淀装置的入水口,调节沉淀装置的出水口连通蒸发结晶器的入水口；浓缩塔的出风口和入风口均连通除尘器与湿法脱硫吸收塔之间的烟气管道。本发明能够通过不同品质的能量综合混用,降低处理脱硫废水的成本,同时不对原有系统及灰渣品质造成影响。(The invention discloses a desulfurization wastewater treatment system and a method, wherein the system comprises a dust remover, a wet desulfurization absorption tower, a wastewater collection tank, a concentration tower, an adjusting and precipitating device and an evaporative crystallizer; the dust remover is communicated with the wet desulphurization absorption tower through a flue gas pipeline; the water outlet of the wet desulphurization absorption tower is communicated with a wastewater collection tank, the water outlet of the wastewater collection tank is communicated with the water inlet of a concentration tower, the water outlet of the concentration tower is communicated with the water inlet of an adjusting and precipitating device, and the water outlet of the adjusting and precipitating device is communicated with the water inlet of an evaporative crystallizer; the air outlet and the air inlet of the concentration tower are both communicated with a flue gas pipeline between the dust remover and the wet desulphurization absorption tower. The invention can comprehensively mix and use energy with different qualities, reduce the cost for treating the desulfurization wastewater and simultaneously not influence the original system and the quality of ash slag.)

1. A desulfurization wastewater treatment system is characterized by comprising a dust remover, a wet desulfurization absorption tower, a wastewater collection tank, a concentration tower and an evaporative crystallizer;

the dust remover is communicated with the wet desulphurization absorption tower through a flue gas pipeline;

the water outlet of the wet desulphurization absorption tower is communicated with a wastewater collection tank, the water outlet of the wastewater collection tank is communicated with the water inlet of a concentration tower, and the water outlet of the concentration tower is communicated with the water inlet of an evaporative crystallizer;

the air outlet and the air inlet of the concentration tower are both communicated with a flue gas pipeline between the dust remover and the wet desulphurization absorption tower.

2. The desulfurization wastewater treatment system of claim 1, wherein the evaporative crystallizer is in communication with a vapor outlet and a vapor inlet of a vapor compressor.

3. The desulfurization wastewater treatment system of claim 1, wherein the air outlet of the concentration tower is arranged at the top of the concentration tower, the water inlet and the air inlet of the concentration tower are both arranged at the middle part of the concentration tower, and the water outlet of the concentration tower is arranged at the lower part of the concentration tower.

4. The desulfurization wastewater treatment system of claim 1, further comprising a regulation and precipitation device, wherein the water inlet of the regulation and precipitation device is communicated with the water outlet of the concentration tower, and the water outlet of the regulation and precipitation device is communicated with the water inlet of the evaporative crystallizer.

5. The desulfurization wastewater treatment system according to any one of claims 1 to 4, wherein the system further comprises a denitrator, an air preheater, and a stack; the denitration device is communicated with a flue gas main pipeline of the coal-fired power plant, and the denitration device, the air preheater, the dust remover, the wet desulphurization absorption tower and the chimney are communicated in sequence through the flue gas pipeline.

6. A desulfurization wastewater treatment method, comprising the steps of:

1) the desulfurization wastewater enters a concentration tower, the desulfurization wastewater is concentrated by using the heat of the flue gas treated by a dust remover, the concentrated wastewater obtained after concentration is introduced into a regulation and precipitation device, and the flue gas discharged from the concentration tower enters a wet desulfurization absorption tower;

2) clarifying and separating the concentrated wastewater by using an adjusting and precipitating device to obtain clarified liquid and large-particle precipitates, and discharging the clarified liquid into an evaporation crystallizer;

3) the clear liquid is evaporated and crystallized in an evaporation crystallizer to obtain solid crystals and condensed clean water.

7. The desulfurization wastewater treatment method of claim 6, wherein the heat energy of the evaporative crystallizer is derived from a vapor compressor, and condensed clean water obtained by the evaporative crystallizer is reused for the vapor compressor.

Technical Field

The invention relates to the technical field of industrial wastewater treatment, in particular to a coal-fired power plant desulfurization wastewater treatment system and a desulfurization wastewater treatment method.

Background

SO₂Is one of the main atmospheric pollutants faced by human beings at present, SO in air₂Too high a content may cause acid rain, damaging crops and buildings. SO (SO)₂It can also be adsorbed on dust in the air and enter human body through respiratory tract, which seriously damages human health. And most of SO₂The emissions of (b) are derived from coal combustion, for example: in a thermal power plant, industrial coal, heating and the like, a large amount of SO is generated in the process of burning the coal₂。

In order to reduce SO in the process of burning coal₂The emission of (2) and the flue gas desulfurization are treatment modes widely adopted at present. For example: in coal-fired power plants, limestone/gypsum wet flue gas desulfurization processes are commonly used to desulfurize flue gas. However, a large amount of high-hardness desulfurization wastewater containing dissolved salts, suspended solids, heavy metal ions and the like is generated in the wet desulfurization process, and cannot be directly discharged or recycled.

Currently, to realize zero discharge of desulfurization waste water, the method generally adopts the method comprising: chemical pretreatment, concentration and decrement, and concentrated water end treatment. In the related technology, the chemical cost in the chemical pretreatment stage is high, and the energy consumption cost of evaporative crystallization adopted in concentration reduction and concentrated water tail end treatment is high, so that the operation cost of the desulfurization wastewater zero-discharge system is high, while the salt content in ash exceeds the standard due to the adoption of flue spray drying and other modes in the tail end treatment, so that the subsequent comprehensive utilization is difficult, and meanwhile, the flue spray mode possibly causes the corrosion of a flue system, and the stability and the reliability of the system operation are influenced.

Therefore, the operation cost of the desulfurization wastewater zero-discharge system in the related technology is high, and the tail end treatment after concentration adopts a flue gas spray drying mode to cause certain influence on comprehensive utilization of ash residues and the like.

Disclosure of Invention

The invention aims to provide a desulfurization wastewater treatment system and method based on energy mixed utilization, and aims to solve the problems that in the related art, a desulfurization wastewater zero-discharge system is high in operation cost, the comprehensive utilization of ash is affected and a flue system is corroded due to the fact that salt is not completely separated.

In order to solve the technical problems, the invention adopts the following technical scheme:

a desulfurization wastewater treatment system comprises a dust remover, a wet desulfurization absorption tower, a wastewater collection tank, a concentration tower, an adjusting and precipitating device and an evaporation crystallizer;

the dust remover is communicated with the wet desulphurization absorption tower through a flue gas pipeline;

the water outlet of the wet desulphurization absorption tower is communicated with a wastewater collection tank, the water outlet of the wastewater collection tank is communicated with the water inlet of a concentration tower, the water outlet of the concentration tower is communicated with the water inlet of an adjusting and precipitating device, and the water outlet of the adjusting and precipitating device is communicated with the water inlet of an evaporative crystallizer;

the air outlet and the air inlet of the concentration tower are both communicated with a flue gas pipeline between the dust remover and the wet desulphurization absorption tower.

Preferably, the evaporative crystallizer is in communication with a vapor outlet and a vapor inlet of a vapor compressor.

Preferably, the air outlet of the concentration tower is arranged at the top of the concentration tower, the water inlet and the air inlet of the concentration tower are both arranged in the middle of the concentration tower, and the water outlet of the concentration tower is arranged at the lower part of the concentration tower.

In the invention, the system also comprises a denitration device, an air preheater and a chimney; the denitration device is communicated with a flue gas main pipeline of the coal-fired power plant, and the denitration device, the air preheater, the dust remover, the wet desulphurization absorption tower and the chimney are communicated in sequence through the flue gas pipeline.

The invention also provides a desulfurization wastewater treatment method, which comprises the following steps:

1) the desulfurization wastewater enters a concentration tower, the desulfurization wastewater is concentrated by using the heat of the flue gas treated by a dust remover, the concentrated wastewater obtained after concentration is introduced into a regulation and precipitation device, and the flue gas discharged from the concentration tower enters a wet desulfurization absorption tower;

2) clarifying and separating the concentrated wastewater by using an adjusting and precipitating device to obtain clarified liquid and large-particle precipitates, and discharging the clarified liquid into an evaporation crystallizer;

3) the clear liquid is evaporated and crystallized in an evaporation crystallizer to obtain solid crystals and condensed clean water.

Preferably, the heat energy of the evaporative crystallizer is derived from a vapor compressor.

According to a preferred embodiment of the present invention, a desulfurization wastewater treatment system is applied to a coal-fired power plant, wherein flue gas generated by the coal-fired power plant passes through a flue gas pipeline, is sequentially introduced into a denitration device, an air preheater, a dust remover and a wet desulfurization absorption tower, and is then discharged to the outside, and the flue gas passes through the wet desulfurization absorption tower to generate desulfurization wastewater, the system comprising:

the waste water collecting tank is communicated with the water outlet of the wet desulphurization absorption tower and is used for collecting the desulphurization waste water discharged by the wet desulphurization absorption tower;

the water inlet of the concentration tower is communicated with the water outlet of the wastewater collection pool, and the air inlet of the concentration tower is communicated with the flue gas pipeline behind the dust remover and is used for carrying out heat exchange, evaporation and concentration on the desulfurization wastewater by utilizing the heat of the flue gas in the pipeline;

the water inlet of the evaporation crystallizer is communicated with the water outlet of the concentration tower or is communicated with the water inlet of the adjusting and precipitating device, the evaporation crystallizer adopts an electric energy-driven mechanical vapor compressor to provide a heat source, concentrated desulfurization wastewater is evaporated to form crystalline solids, and the complete separation of brine is realized.

The evaporative crystallizer adopts a high-flow-rate large-flow-rate circulating evaporative crystallization system, and heat energy required by evaporative crystallization comes from a mechanical vapor compressor driven by electric energy to finally form crystals. Calcium sulfate contained in the desulfurization wastewater is used as a seed crystal to prevent scaling and blockage in the evaporation and crystallization process.

Preferably, the air outlet of the concentration tower is communicated with the part between the dust remover and the wet desulphurization absorption tower.

Preferably, an adjusting and precipitating device is communicated between the water outlet of the concentration tower and the water inlet of the evaporative crystallizer, and is used for clarifying and separating clarified liquid and precipitate from the concentrated desulfurization wastewater through the coagulating sedimentation device so as to discharge the clarified liquid into the evaporative crystallizer.

A desulfurization wastewater treatment method based on above-mentioned system is applied to coal fired power plant, the flue gas that coal fired power plant produced passes through the flue gas trunk line, discharges to the external world after letting in denitrification facility, air heater, dust remover and wet flue gas desulfurization absorption tower in proper order, and the flue gas produces desulfurization wastewater after passing through the wet flue gas desulfurization absorption tower, the method includes:

collecting the desulfurization wastewater discharged by the wet desulfurization absorption tower;

concentrating the desulfurization wastewater in a concentration tower by using the heat of the flue gas;

and finally evaporating and drying the concentrated desulfurization wastewater into crystalline solid by using the evaporation crystallizer.

Preferably, the method further comprises:

discharging the flue gas after the desulfurization wastewater is concentrated into an inlet flue of the wet desulfurization absorption tower;

and collecting and using the condensed water after the desulfurization wastewater is evaporated by the evaporative crystallizer.

In the invention, the heat of the discharged flue gas is utilized to concentrate the desulfurization wastewater in the concentration tower, and the electric energy is utilized to drive the steam compressor to evaporate the concentrated desulfurization wastewater in the evaporation crystallizer, so as to realize zero discharge of the desulfurization wastewater. Chemical pretreatment of the desulfurization wastewater is omitted, so that the chemical pretreatment agent cost is saved, the heat energy and the electric energy of the flue gas discharged by the coal-fired power plant are mixed and utilized, and the desulfurization wastewater is subjected to concentration and crystallization treatment, so that the energy consumption for treating the desulfurization wastewater is reduced, and therefore, the desulfurization wastewater treatment system provided by the invention can reduce the cost for treating the desulfurization wastewater. According to the invention, salt in the wastewater finally forms crystalline solids, and does not enter the original coal-fired power plant system, so that the problems of influencing ash quality, utilization and the like are avoided, the concentrated wastewater does not return to the flue gas system, the problems of corrosion, blockage and the like on the flue gas system are avoided, and the operation stability of the coal-fired power plant is effectively improved.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings needed for the embodiment or the prior art description will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic view of a desulfurization waste water treatment system of the present invention;

FIG. 2 is a flow chart of the desulfurization waste water treatment method of the present invention.

Reference numerals: 12. a denitration device; 13. an air preheater; 14. a dust remover; 15. a wet desulfurization absorption tower; 16. a chimney; 21; a wastewater collection tank; 22. a concentration tower; 23. adjusting the precipitation device; 24. an evaporative crystallizer; 25. a vapor compressor; 201. 202, 203 and 204 are steps of a desulfurization waste water treatment method.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

As shown in fig. 1, a desulfurization wastewater treatment system applied to a coal-fired power plant, wherein flue gas generated by the coal-fired power plant passes through a flue gas pipeline, is sequentially introduced into a denitration device 12, an air preheater 13, a dust remover 14 and a wet desulfurization absorption tower 15, and is discharged to the outside through a chimney 16.

The waste water collecting tank 21 is communicated with the water outlet of the wet desulphurization absorption tower 15 and is used for collecting the desulphurization waste water in the wet desulphurization absorption tower 15;

a water inlet of the concentration tower 22 is communicated with a water outlet of the wastewater collection tank 21, and an air inlet of the concentration tower 22 is communicated with a flue gas pipeline behind the dust remover and is used for concentrating the desulfurization wastewater by utilizing the heat of the flue gas in the pipeline;

the adjusting and precipitating device 23 is used for adjusting and precipitating the concentrated solution wastewater passing through the concentrating tower 22 in the adjusting and precipitating device 23 to separate large-particle solids and form clear liquid only containing small-particle suspended matters;

an evaporation crystallizer 24, wherein a water inlet of the evaporation crystallizer 24 is communicated with a water outlet of the adjusting and precipitating device 23, heat in the operation process of the evaporation crystallizer comes from an electric-driven vapor compressor 25, the vapor compressor 25 applies work to secondary vapor generated by evaporation of waste water in the evaporation crystallizer, the vapor with the enthalpy value increased is sent into the evaporation crystallizer again to heat the waste water, and the circulation is carried out, so that the waste water is finally evaporated into solid crystals and condensed clean water, and the complete separation of salt water is realized.

Wherein, the boiler of the coal-fired power plant carries out coal-fired reaction, thereby generating flue gas with high temperature, and the flue gas is mixed with dust and sulfur dioxide SO₂Nitrogen oxide, and the like, in order to avoid the environmental pollution caused by the flue gas, the flue gas needs to be subjected to treatment including denitration, cooling, dust removal and desulfurization, and then can be discharged into the atmosphere.

In addition, before the temperature reduction, the temperature of the flue gas discharged by the coal-fired power plant is very high, such as: the temperature is between 90 ℃ and 120 ℃, and the smoke has higher heat.

Moreover, the desulfurization wastewater can be concentrated by 60-80% through the concentration tower 22, and the volume of the desulfurization wastewater entering the evaporative crystallizer 24 is greatly reduced.

Like this, utilize flue gas heat to carry out the heat transfer concentration to desulfurization waste water earlier to reduce the water content of desulfurization waste water, thereby reduce the volume of desulfurization waste water. And then the concentrated desulfurization wastewater is completely evaporated by using an evaporation crystallizer driven by electric energy to form solid crystals, so that zero discharge of wastewater is achieved.

As shown in fig. 1, the coal-fired power plant is further provided with a chimney 16, and the wet desulfurization absorption tower 15 is communicated with the chimney 16 so as to discharge flue gas subjected to denitration, temperature reduction, dust removal, desulfurization and the like to the atmosphere.

The denitration device 12 may be any one or more of a selective catalytic reduction denitration device (SCR), a selective non-catalytic reduction denitration device (SNCR), and the like.

In addition, the air preheater 13 can preheat air entering the boiler by using the temperature of the flue gas, so that the heat can be recycled while the temperature of the flue gas is reduced.

The air outlet of the concentration tower 22 is communicated with the pipeline part between the dust remover 14 and the wet desulphurization absorption tower 15.

Wherein, fresh process water is needed to be supplemented into the wet desulphurization absorption tower 15 to ensure the efficiency of wet desulphurization in the wet desulphurization absorption tower 15. The air outlet of the concentration tower 22 is communicated with the flue gas pipeline in front of the wet desulphurization absorption tower, so that the water vapor formed by evaporation in the concentration tower 22 can enter the wet desulphurization absorption tower 15 to supplement the water amount in the wet desulphurization absorption tower 15.

Therefore, the water in the desulfurization wastewater can be recycled, and the aim of reducing the supplementary water amount in the wet desulfurization absorption tower is achieved.

As shown in fig. 1, the air inlet and the air outlet of the concentration tower 22 are both communicated with the flue gas pipeline portion between the dust remover 14 and the wet desulphurization absorption tower 15.

In this embodiment, the flue gas after utilizing the dust removal is concentrated desulfurization waste water, avoids in the dust in the flue gas gets into desulfurization waste water, causes the system to block up to can promote desulfurization waste water's treatment effeciency.

In the embodiment, the salt water separation of the desulfurization wastewater is finally realized, the solid salt can be recycled, and the condensed water can be directly recycled in a factory. The problem of influence etc. is caused to the quality of lime-ash in having avoided the salinity to get into flue gas system, can not cause the corruption scheduling problem to flue gas system simultaneously, has promoted coal fired power plant's operating stability.

An adjusting and precipitating device 23 is communicated between the water outlet of the concentration tower 22 and the water inlet of the evaporative crystallizer 24, and is used for separating clear liquid and large-particle precipitates from the concentrated desulfurization wastewater through adjusting and precipitating of the adjusting and precipitating device 23 so as to send the clear liquid into the evaporative crystallizer 24.

Like this, can reduce the impurity that gets into in the desulfurization waste water of evaporative crystallizer, alleviate impurity recovery's work burden to reduce and discharge to external impurity content, promote this desulfurization waste water treatment system's environmental protection performance.

In addition, after the precipitated impurities in the precipitation device are regulated to be precipitated to a certain amount, the impurities can be uniformly collected, so that the impurities in the desulfurization wastewater can be conveniently collected.

In the invention, the heat of the discharged flue gas is utilized to concentrate the desulfurization wastewater in the concentration tower, and the electric energy is utilized to drive the steam compressor to evaporate the concentrated desulfurization wastewater in the evaporation crystallizer, so as to realize zero discharge of the desulfurization wastewater. Chemical pretreatment of the desulfurization wastewater is omitted, so that the chemical pretreatment agent cost is saved, the heat energy and the electric energy of the flue gas discharged by the coal-fired power plant are mixed and utilized, and the desulfurization wastewater is subjected to concentration and crystallization treatment, so that the energy consumption for treating the desulfurization wastewater is reduced, and therefore, the desulfurization wastewater treatment system provided by the invention can reduce the cost for treating the desulfurization wastewater. According to the invention, the salt in the wastewater finally forms a crystalline solid, and does not enter the original coal-fired power plant system, so that the problems of influencing the quality and utilization of ash and slag and the like are avoided, and the operation stability of the coal-fired power plant is effectively improved.

As shown in fig. 2, a desulfurization waste water treatment method based on energy mixed utilization. The method is applied to a coal-fired power plant, the flue gas generated by the coal-fired power plant is sequentially introduced into a denitration device, an air preheater, a dust remover and a wet desulphurization absorption tower through a flue gas main pipeline and then is discharged to the outside, and the flue gas generates desulphurization wastewater after passing through the wet desulphurization absorption tower, and the method comprises the following steps:

and step 201, collecting the desulfurization wastewater in the wet desulfurization absorption tower.

And step 202, concentrating the desulfurization wastewater by using the heat of the flue gas in the pipeline.

And 203, evaporating the concentrated desulfurization wastewater by using the evaporation crystallizer driven by the electric energy so as to dry the desulfurization wastewater into solid crystals, thereby realizing brine separation.

And 204, discharging the flue gas at the air outlet of the concentration tower into the inlet of the wet desulphurization absorption tower.

The method provided by the invention can be applied to the desulfurization wastewater treatment system as shown in fig. 1, and can obtain the same beneficial effects, and the method is not repeated herein for avoiding repetition.

Conventional technical knowledge in the art can be used for the details which are not described in the present invention.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.