CN111569630B - Wet desulfurization system and wet desulfurization method - Google Patents

Wet desulfurization system and wet desulfurization method Download PDF

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Publication number
CN111569630B
CN111569630B CN202010459180.5A CN202010459180A CN111569630B CN 111569630 B CN111569630 B CN 111569630B CN 202010459180 A CN202010459180 A CN 202010459180A CN 111569630 B CN111569630 B CN 111569630B
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flue gas
section
tower
water
evaporator
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CN111569630A (en
Inventor
李玖重
孙志钦
李国智
周天宇
高晓红
郜建松
张婧帆
高跃成
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China Petroleum and Chemical Corp
Sinopec Engineering Group Co Ltd
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China Petroleum and Chemical Corp
Sinopec Engineering Group Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/78—Liquid phase processes with gas-liquid contact
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D47/00—Separating dispersed particles from gases, air or vapours by liquid as separating agent
    • B01D47/06—Spray cleaning
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/002—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by condensation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases

Abstract

The invention discloses a wet desulphurization system and a wet desulphurization method, wherein a generator and a waste water evaporator are arranged in a split heat pump system to continuously reduce the temperature of sulfur-containing flue gas introduced into a desulphurization tower to be below the acid dew point temperature, and promote the SO of the flue gas3Condensation and first growth of fine contaminants. And the sulfur-containing flue gas is used for evaporating the desulfurization wastewater in the wastewater evaporator, and the generated steam is injected into the desulfurization tower to establish a supersaturated steam environment so as to promote the small pollutants in the desulfurization flue gas to grow up for the second time. Meanwhile, certain cold quantity and heat quantity are prepared through the generator and the deep evaporator, the cold quantity is used for deep cooling of purified flue gas, a supersaturated water vapor environment is constructed, fine pollutants are promoted to grow for the third time, and the heat quantity is used for heating purified flue gas out of the desulfurizing tower, so that the temperature of the purified flue gas is increased, and the white smoke phenomenon is eliminated. Further realizing the purposes of removing fine pollutants in the desulfurized flue gas, eliminating white smoke and reducing the emission of desulfurized waste water.

Description

Wet desulfurization system and wet desulfurization method
Technical Field
The invention relates to the technical field of desulfurization, in particular to a wet desulfurization system and a wet desulfurization method.
Background
The flue gas generated by burning of boilers, incinerators, catalytic cracking devices and the like can be discharged into the atmosphere after being desulfurized, and the sulfur-containing flue gas is generally treated by wet desulphurization. At present, the purified flue gas after desulfurization still contains a large amount of submicron-grade SO3The pollutants such as fog drops, fine particles, volatile salts and the like are discharged into the atmosphere to form haze weather, and the visibility of the surrounding environment and the physical and psychological health of residents are seriously influenced. The removal efficiency of the submicron order fine pollutants in the desulfurization flue gas in a wet desulfurization system is low, and generally the removal efficiency does not exceed 40%.
Fine particulate matter, SO, to traditional pollutant control facilities3The removal efficiency of submicron order fine pollutants such as acid mist and the like needs to be improved urgently, and various physical or chemical actions are adopted to ensure that fine particles and SO3The removal of acid mist and other fine pollutants after the growth is an important technical means for enhancing the removal of submicron fine pollutants by wet desulphurization.
Patent 200710132250.0 discloses a method for promoting removal of PM2.5 by applying water vapor phase change in wet flue gas desulfurization, which adopts a mode of adding steam into tower inlet flue gas and desulfurization purification flue gas to make the flue gas in the washing process and the purified flue gas reach a supersaturated state twice, thereby effectively realizing removal of PM 2.5. But the method has the disadvantages of high steam consumption, high energy consumption and poor economic performance of system operation. Patent 201710042816.4 discloses a wet desulfurization method for removing fine particles and SO3The acid mist method is to spray atomized water and spray cooling to purify fume inside the inlet flue of desulfurizing tower to establish supersaturated environment and to make the particle matter and SO in the fume to be purified3The acid mist is condensed and grows up and is intercepted and removed by a subsequent high-efficiency demister. The method establishes a supersaturated environment by injecting cooling water, has large water consumption of the system, greatly increases the corresponding treatment capacity of the desulfurization waste water, has high operation cost of the desulfurization system, and easily breaks the water balance of the desulfurization system to influence the overall desulfurization efficiency.
In addition, the above desulfurization method may generate a large amount of white smoke after being discharged into the air, may cause strong visual pollution in case of wasting a large amount of heat energy and water resources, and may cause a large burden of desulfurization wastewater treatment.
Therefore, the white smoke phenomenon, wastewater treatment, fine pollutant removal and the like are all problems which are urgently needed to be solved by the existing wet desulphurization system.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The present invention aims to provide a wet desulfurization system and a wet desulfurization method to improve the above problems.
The invention is realized by the following steps:
on one hand, the embodiment of the invention provides a wet desulphurization system, which comprises a desulphurization tower and a split type heat pump system, wherein the inside of the desulphurization tower sequentially comprises a cooling absorption section, a steam injection section, a deep cooling section, a flue gas temperature raising section and a flue gas outlet section from bottom to top.
The split type heat pump system comprises a generator, a waste water evaporator, a cryogenic evaporator, an absorber, a heat exchanger and a sulfur-containing flue gas inlet pipe communicated with a cooling absorption section of the desulfurizing tower.
The generator and the waste water evaporator are sequentially arranged along the flowing direction of the sulfur-containing flue gas inlet pipe so as to realize the continuous cooling of the sulfur-containing flue gas by the generator and the waste water evaporator.
The desulfurization waste liquid outlet at the bottom of the desulfurization tower is sequentially communicated with the absorber and the waste water evaporator, and the steam outlet of the waste water evaporator is communicated with the steam injection section of the desulfurization tower, so that the absorber and the waste water evaporator can continuously heat the desulfurization waste liquid, and steam is generated to carry out the desulfurization tower.
The generator is sequentially communicated with the heat exchanger and the absorber, so that the refrigerating fluid discharged by the generator after heat exchange can be cooled by the heat exchanger, cooled and diluted by the absorber, returned to the heat exchanger to exchange heat with the refrigerating fluid before dilution, heated and then enters the generator.
The generator still communicates with the heat transfer device intercommunication of the flue gas section of heating of desulfurizing tower to in making the solvent steam that the refrigerant fluid intensifies the production in the generator get into the heat transfer device of desulfurizing tower, the condensate outlet and the cryogenic evaporator intercommunication of the heat transfer device of flue gas section of heating, still be provided with the choke valve that is used for the cooling between heat transfer device's condensate outlet and the cryogenic evaporator, the cryogenic evaporator still communicates with the degree of depth cooling section of desulfurizing tower, so that come from the cryogenic reflux water of cryogenic reflux section is in with come from in the cryogenic evaporator the condensate heat transfer cooling back of flue gas section of heating, the rethread the degree of depth cooling section of desulfurizing tower comes from the condensate water gasification is steam after being heated and intensification of flue gas section of heating.
The steam outlet of the cryogenic evaporator is communicated with the absorber to dilute and cool the refrigerant liquid from the generator.
Optionally, a water heating channel is further disposed in the absorber, and the water heating channel is provided with a normal-temperature water inlet and a heating water outlet so as to heat the normal-temperature water by heat released by the refrigerant liquid.
Optionally, at least two steam injection ports of the steam injection section of the desulfurization tower are arranged at equal intervals along the same horizontal plane of the inner wall of the desulfurization tower in the circumferential direction.
Optionally, the steam injection direction of each steam injection port is inclined downwards and forms an angle of 10-60 degrees, preferably 20-45 degrees, more preferably 30 degrees with the inner wall surface of the desulfurizing tower; optionally, the angle of inclination of all the steam injection ports is the same.
Optionally, a spray washing section is further arranged between the steam injection section and the deep cooling section of the desulfurization tower, and optionally, a return pipe communicated with the top is further arranged at the bottom of the spray washing section.
Optionally, the desulfurizing tower is further provided with a demisting section between the deep cooling section and the flue gas heating section, and preferably, the demister of the demisting section comprises any one of a water droplet separator, a baffle demister, a cyclone separator and an electrostatic demister.
On the other hand, the embodiment of the present invention further provides a wet desulphurization method using the wet desulphurization system, which includes:
the sulfur-containing flue gas with the temperature of more than or equal to 150 ℃ sequentially passes through the generator and the waste water evaporator for continuous cooling, then enters a cooling absorption section of the desulfurizing tower, and then sequentially rises in the desulfurizing tower to pass through a steam injection section, a deep cooling section, a flue gas temperature raising section and a flue gas outlet section.
And introducing the desulfurization waste liquid discharged from the bottom of the desulfurization tower into an absorber for heating, introducing the desulfurization waste liquid into a waste water evaporator for heat exchange to generate steam, and introducing the generated steam into a steam injection section of the desulfurization tower.
The method comprises the steps of carrying out heat exchange on rich liquid refrigerating fluid obtained after solvent steam is generated through evaporation and evaporation in a generator with sulfur-containing flue gas, cooling through a heat exchanger, then cooling through an absorber and diluting to obtain diluted refrigerating fluid, returning the diluted refrigerating fluid to the heat exchanger to exchange heat with the rich liquid refrigerating fluid before dilution, heating, and then entering the generator.
The heat exchange device of the flue gas temperature raising section for introducing the solvent steam generated by the heat exchange of the refrigerating fluid into the desulfurizing tower in the generator heats up the rising flue gas, the condensed water generated after the heat exchange is cooled through the throttle valve and then enters the cryogenic evaporator, and the condensed water is gasified into the solvent steam after being subjected to the heat exchange with the reflux water of the deep cooling section, and the solvent steam returns to the deep cooling section again after being cooled by the reflux water from the deep cooling section to cool the flue gas.
And introducing the solvent steam generated by the cryogenic evaporator into the absorber to dilute and cool the refrigerant liquid from the generator.
Optionally, the temperature of the sulfur-containing flue gas entering the waste water evaporator is 110-140 ℃, and the temperature of the flue gas entering the desulfurizing tower is 80-110 ℃.
Optionally, when the desulfurization tower is provided with a spray washing section and a demisting section, the cooling absorption section is washed by slurry at the bottom of the desulfurization tower, then the slurry flows upwards to be mixed with steam injected by the steam injection section, enters the spray washing section for washing, is cooled by deep cold water from the evaporator, enters the demisting section, enters the flue gas heating section again, raises the temperature to above 90 ℃, and is discharged from the flue gas outlet section of the desulfurization tower.
Optionally, the return water temperature of the deep cooling section is 20-40 ℃, and the temperature of deep cooling water from the evaporator is 5-25 ℃.
Optionally, the refrigerant fluid used for exchanging heat with the sulfur-containing flue gas in the generator and generating the solvent vapor comprises any one of a lithium bromide solution, ammonia water and a lithium nitrate solution, preferably a lithium bromide solution.
The invention has the following beneficial effects:
the temperature of the flue gas entering the desulfurizing tower is reduced by the split heat pump system, SO that the temperature of the flue gas can be reduced to be below the acid dew point temperature, and the SO of the flue gas is promoted3The condensation and the tiny pollutants grow up for the first time, the desulfurization waste water is evaporated through the flue gas of the desulfurization tower, the generated water vapor is injected into the desulfurization tower, a supersaturated water vapor environment is established, the flue gas cooled by the washing of the slurry at the bottom of the desulfurization tower acts, and the tiny pollutants in the desulfurization flue gas grow up for the second time. Meanwhile, solvent steam is prepared by heat exchange between the refrigerating fluid in the generator and the high-temperature sulfur-containing flue gas and is used for heating the purified flue gas out of the desulfurizing tower, so that the temperature of the purified flue gas is increased, the white smoke phenomenon is eliminated, cooling water obtained by condensation after the heat exchange of the water steam is further cooled by the evaporator and then is introduced into the desulfurizing tower, the purified flue gas is deeply cooled, a supersaturated water vapor environment is constructed, and the growth of fine pollutants for the third time is promoted. Further realizing the purposes of removing fine pollutants in the desulfurized flue gas, eliminating white smoke and reducing the emission of desulfurized waste water.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic view of a wet desulfurization system of example 1 of the present invention;
FIG. 2 is a schematic process flow diagram of a wet desulfurization method according to example 2 of the present invention.
Icon: 1-a generator; 2-a waste water evaporator; 3-a cryogenic evaporator; 4-an absorber; 5-a heat exchanger; 6-a desulfurizing tower; a-a cooling absorption section; b-a steam injection section; c, a spray washing section; d-a deep cooling section; e-demisting section; f, a flue gas temperature rising section; g-flue gas outlet section.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
Referring to the attached drawing 1, the embodiment provides a wet desulphurization system, which includes a desulphurization tower 6 and a split type heat pump system, wherein the inside of the desulphurization tower 6 sequentially includes, from bottom to top, a cooling absorption section a, a steam injection section B, a spray washing section C, a deep cooling section D, a demisting section E, a flue gas temperature raising section F and a flue gas outlet section G. The split type heat pump system comprises a generator 1, a waste water evaporator 2, a cryogenic evaporator 3, an absorber 4, a heat exchanger 5 and a sulfur-containing flue gas inlet pipe communicated with a cooling absorption section A of a desulfurizing tower 6.
It is noted that in other embodiments, the spray wash section C or the demister section E may be omitted as desired.
Along the sulphur flue gas that contains advances pipe flow direction and has set gradually generator 1 and waste water evaporator 2, generator 1 is provided with the import of sulphur flue gas and contains the export of sulphur flue gas, and high temperature flue gas passes through the import of sulphur flue gas and gets into generator 1 to take place the heat transfer with the refrigerating fluid in generator 1, carry out the first cooling to sulphur flue gas. The sulfur-containing flue gas is discharged from a sulfur-containing flue gas outlet of the generator 1, enters the waste water evaporator 2 through a pipeline, and is cooled for the second time with the desulfurization waste water in the waste water evaporator 2, the sulfur-containing flue gas cooled for the second time can be reduced to be below the acid dew point temperature, and further the SO of the flue gas is promoted3Condensation and first growth of fine contaminants. Wherein, the high-temperature sulfur-containing flue gas is subjected to dividing wall type heat exchange in the generator 1 and the waste water evaporator 2, and certainly, according to the requirements of process conditions,in the waste gas evaporator in other embodiments, the high-temperature flue gas can also exchange heat with the desulfurization waste water directly.
The generator 1 is provided with a refrigeration channel, the refrigeration channel is provided with a refrigerant liquid inlet, a refrigerant liquid outlet and a steam outlet, the steam outlet is communicated with a heat exchange device of a flue gas heating section F of the desulfurizing tower 6, and solvent steam generated after the refrigerant liquid absorbs heat of high-temperature sulfur-containing flue gas enters the heat exchange device of the flue gas heating section F to heat rising purified flue gas, so that the temperature of the purified flue gas rises, and white smoke is eliminated. The heat exchange device of the flue gas temperature raising section F and the flue gas in the desulfurizing tower perform dividing wall type heat exchange, namely the heat exchange device can be a tubular heat exchanger or a plate heat exchanger arranged in the desulfurizing tower 6, and in the embodiment, the heat exchange device is arranged in the desulfurizing tower 6 in a coil pipe mode.
Compared with the traditional split type heat pump system, the condenser part of the traditional heat pump system is integrated inside the desulfurizing tower, so that the effect of eliminating white smoke of purified flue gas is realized, the system structure is simplified, and the energy utilization efficiency is improved.
Referring to fig. 1 again, a condensed water outlet of the heat exchange device of the flue gas temperature rising section F in the desulfurizing tower 6 is communicated with the pipeline of the cryogenic evaporator 3, a throttle valve for cooling is further arranged on the pipeline, and after the flue gas temperature rising section F exchanges heat with purified flue gas, condensate obtained by condensing solvent steam is cooled through the throttle valve and then enters the cryogenic evaporator 3. The cryogenic evaporator is provided with a cryogenic liquid outlet and a cryogenic reflux inlet, the cryogenic liquid outlet is communicated with the cryogenic liquid inlet of the deep cooling section D, and the cryogenic reflux inlet is communicated with the cryogenic liquid outlet of the deep cooling section D. The cooling device of the deep cooling section D performs dividing wall type heat exchange with the flue gas in the desulfurization tower, that is, the cooling device can be a tubular heat exchanger or a plate heat exchanger arranged in the desulfurization tower 6, and in this embodiment, is arranged in the desulfurization tower 6 in a coil pipe manner. And then the condensate entering the cryogenic evaporator 3 exchanges heat with the cryogenic reflux liquid after heat exchange, the cooled cryogenic reflux liquid serving as cooling liquid enters the deep cooling section D again to cool the flue gas, and the condensate from the flue gas temperature raising section F is heated and gasified under the negative pressure condition to be solvent steam and enters the absorber 4.
Furthermore, a refrigeration channel of the generator 1 is sequentially communicated with the heat exchanger 5 and the absorber 4 through pipelines, after heat exchange with high-temperature sulfur-containing flue gas, rich liquid refrigerant obtained after solvent evaporation enters the heat exchanger 5 for cooling, then enters the absorber 4 to be mixed with solvent steam from the cryogenic evaporator to form diluted refrigerant, and then the diluted refrigerant returns to the heat exchanger 5 through a pipeline to exchange heat with the rich liquid refrigerant obtained after solvent evaporation, so that the temperature of the diluted refrigerant is raised and then enters the generator 1.
Meanwhile, one part of the desulfurization wastewater discharged from the bottom of the desulfurization tower 6 is discharged outside, and the other part of the desulfurization wastewater is introduced into the absorber 4 through a pipeline to perform dividing wall type heat exchange and temperature rise, and then further enters the wastewater evaporator 2. The desulfurization waste water is made to generate water vapor in the waste water evaporator 2 by absorbing the heat of the sulfur-containing flue gas at a higher temperature. The steam outlet of the waste water evaporator 2 is communicated with the steam injection section of the desulfurizing tower 6, the desulfurizing waste water is evaporated by entering the flue gas of the desulfurizing tower, the generated steam is injected into the desulfurizing tower 6 to establish a supersaturated steam environment, SO that the small pollutants in the desulfurized flue gas grow up for the second time, and the SO is more favorably used for3And removal of contaminants. Wherein the waste water evaporator 2 periodically discharges sulfur-containing solid waste.
In order to achieve better steam injection effect, at least two steam injection ports are arranged on the steam injection section of the desulfurizing tower. In this embodiment, the number of the two steam injection ports is two, and the two steam injection ports are circumferentially arranged oppositely along the same horizontal plane of the inner wall of the desulfurizing tower. Of course, in other embodiments, when there are more steam injection ports, the steam injection ports are uniformly spaced along the circumference of the same horizontal plane of the inner wall of the desulfurization tower.
Further, in order to enable the steam to better act with the flue gas, the steam injection direction of each steam injection port is inclined downwards and forms an angle of 10-60 degrees, preferably 20-45 degrees, more preferably 30 degrees with the inner wall surface of the desulfurizing tower, and the inclination angles of the steam injection ports are the same. In this embodiment, the injection angle is 30 ° to the inner wall surface of the desulfurization tower, i.e., the injection angle in fig. 1.
In addition, in this embodiment, a water heating channel is further disposed in the absorber, and the water heating channel is provided with a normal-temperature water inlet and a heating water outlet so as to heat the normal-temperature water by heat released by the refrigerant liquid. And (3) heating the normal-temperature water by 10-50 ℃ under the heat of the rich liquid refrigerant, and then leading out the normal-temperature water to a hot user or entering a circulating water system.
In this embodiment, the bottom of the spray washing section C is further provided with a return pipe communicated with the top. In this embodiment, the demister of the demisting section E includes any one of a water droplet separator, a baffle demister, a cyclone separator, and an electrostatic demister.
The wet desulphurization method adopting the wet desulphurization system specifically comprises the following steps:
the sulfur-containing flue gas with the temperature of more than or equal to 150 ℃ is continuously cooled by the generator 1 and the waste water evaporator 2 in sequence, enters the cooling absorption section A of the desulfurizing tower 6, and then sequentially rises in the desulfurizing tower 6 to pass through the steam injection section B, the spray washing section C, the deep cooling section D, the demisting section E, the flue gas heating section F and the flue gas outlet section G. The temperature of the sulfur-containing flue gas entering the waste water evaporator is 110-140 ℃, and the temperature of the flue gas entering the desulfurizing tower is 80-110 ℃.
And introducing the desulfurization waste liquid discharged from the bottom of the desulfurization tower 6 into an absorber 4 to be heated, introducing the desulfurization waste liquid into a waste water evaporator 2 to exchange heat to generate steam, and introducing the generated steam into a steam injection section of the desulfurization tower 6, wherein the temperature of the steam injected into the steam injection section B is 101-120 ℃.
The method comprises the steps of carrying out heat exchange on rich liquid refrigerant obtained after solvent steam is generated through evaporation and evaporation in a generator 1 through a sulfur-containing flue gas, cooling through a heat exchanger 5, cooling through an absorber 4, diluting to obtain diluted refrigerant, returning the diluted refrigerant to the heat exchanger 5, carrying out heat exchange on the diluted refrigerant and the rich liquid refrigerant before dilution, heating, and then entering the generator 1.
The steam generated by the heat exchange of the refrigerating fluid in the generator 1 is introduced into the heat exchange device of the flue gas heating section F of the desulfurizing tower 6 to heat rising flue gas, condensed water generated after heat exchange is cooled through the throttle valve and then enters the cryogenic evaporator, the condensed water and reflux water from the deep cooling section D are subjected to heat exchange, the condensed water is heated and gasified into solvent steam and then enters the absorber, and the reflux water from the deep cooling section D returns to the deep cooling section D for cooling again after being cooled. The return water temperature of the deep cooling section D is 20-40 ℃, and the temperature of deep cooling water is 5-25 ℃.
The solvent vapor produced by the cryogenic evaporator 3 is passed to the absorber 4 for dilution and temperature reduction of the refrigerant liquid from the generator 1.
The flue gas entering the desulfurizing tower is washed by the slurry at the bottom of the desulfurizing tower through the cooling absorption section, then flows upwards to be mixed with the steam injected by the steam injection section B, enters the spraying washing section C for washing, is cooled by the deep cold water from the cryogenic evaporator 3, enters the demisting section E, enters the flue gas temperature raising section F for raising the temperature to be more than 90 ℃, and is discharged from the flue gas outlet section of the desulfurizing tower 6. Specifically, flue gas from the waste water evaporator 2 enters a cooling absorption section A of a desulfurizing tower 6, is washed by slurry at the bottom of the desulfurizing tower, flows upwards after the temperature of the flue gas is reduced by 2-8 ℃, is mixed with steam injected from a steam injection section B, and enters a spraying washing section C. The flue gas enters a deep cooling section D after further washing in a spray washing section C of the desulfurizing tower, is cooled by deep cold water from a cryogenic evaporator 3, and enters a demisting section E after the temperature of the flue gas is reduced by 3-6 ℃. The flue gas enters a flue gas temperature raising section F after entering a demisting section E of the desulfurizing tower to remove fog drops and partial fine pollutants, and is heated by solvent steam from a generator 1 to raise the temperature, and then the temperature is raised to be higher than 90 ℃ and is discharged from a flue gas outlet section G of a desulfurizing tower 6.
The refrigerant fluid used for exchanging heat with the sulfur-containing flue gas in the generator 1 and generating water vapor comprises any one of a lithium bromide solution, ammonia water and a lithium nitrate solution, and the lithium bromide solution is adopted in the embodiment.
Example 2
This example also provides a specific wet desulfurization method using the wet desulfurization system of example 1.
Referring to fig. 2, the number of steam injection ports of the steam injection section B of the desulfurization tower of the wet desulfurization system is two, and the injection angle of the steam injection direction to the wall surface of the desulfurization tower is 30 °. The deep cooling section cryogenic water and the flue gas can adopt a direct contact spray heat exchange type; the refrigerating fluid is a lithium bromide solution; the demister of the demisting section E of the desulfurizing tower is a baffle demister. Among them, the evaporator in fig. 2 is a deep cooling evaporator.
The high-temperature flue gas with the temperature of 180 ℃ from the waste heat boiler enters a generator, the temperature of the flue gas is reduced to 130 ℃, the flue gas enters a waste water evaporator, and the flue gas temperature is reduced to 90 ℃ after the waste water is evaporated, and then the flue gas enters a desulfurizing tower.
After the lithium bromide dilute solution in the generator absorbs the heat of high-temperature flue gas, water vapor is generated and enters a flue gas heating section F of the desulfurizing tower to heat and purify the flue gas, the temperature of the water vapor is reduced, the condensed liquid water is cooled and depressurized by a throttle valve, and the condensed liquid water enters a cryogenic evaporator after the temperature is reduced to 15 ℃. The dilute lithium bromide solution in the generator absorbs heat to generate water vapor at 110 ℃, and then the water vapor is changed into rich lithium bromide solution which enters a heat exchanger.
The low-temperature low-pressure liquid water enters the deep cooling section D for cooling after absorbing the heat of the 30 ℃ return water from the deep cooling section D of the desulfurization tower, the condensed water from the flue gas temperature raising section F is gasified into 20 ℃ water vapor in the deep cooling section D and enters the absorber, and the return water temperature of the deep cooling section D is reduced to become 20 ℃ deep cold water which enters the deep cooling section D of the desulfurization tower for cooling and purifying flue gas.
After the water vapor enters the absorber, the water vapor is absorbed by the lithium bromide rich solution from the heat exchanger to release heat, and the water at the normal temperature of 30 ℃ is heated to 70 ℃ and is led out to a heat user; the temperature of the part of the desulfurized wastewater at 56 ℃ from the bottom of the desulfurization tower is raised to 80 ℃ and then the desulfurized wastewater enters a wastewater evaporator.
The lithium bromide rich solution absorbs water vapor and is changed into dilute solution, the dilute solution is led out from the absorber and enters the heat exchanger to exchange heat with the lithium bromide rich solution from the generator, the temperature of the lithium bromide rich solution is reduced to 85 ℃ and then enters the absorber, and the temperature of the lithium bromide dilute solution is increased to 105 ℃ and then enters the generator to absorb high-temperature flue gas heat to generate water vapor for heat pump circulation.
And the desulfurization wastewater heated to 80 ℃ in the absorber enters a wastewater evaporator, absorbs the heat of the flue gas to generate 105 ℃ water vapor, and the water vapor is injected into the desulfurization tower from a desulfurization tower vapor injection section B.
The flue gas from the waste water evaporator enters a cooling absorption section A of the desulfurizing tower and is washed by slurry at the bottom of the desulfurizing tower, the temperature of the flue gas is reduced to 54 ℃, then the flue gas flows upwards to be mixed with steam injected by a steam injection section, and the temperature is increased to 56 ℃ and then the flue gas enters a spraying washing section C. And returning a part of the slurry at the bottom of the desulfurization tower to the cooling absorption section A for washing flue gas, discharging a part of the slurry outside for treatment, and feeding a part of the slurry into an absorber for heating and then into a wastewater evaporator.
The flue gas enters a spray washing section C of the desulfurizing tower for further washing and then enters a deep cooling section D, and is cooled by cryogenic water at 20 ℃ from an evaporator, and the temperature of the flue gas is reduced to 52 ℃ and then enters a demisting section E. Removing fog drops and fine pollutants in a demisting section of the desulfurizing tower, reducing the total amount of purified smoke fine pollutants by 85%, then enabling the smoke to enter a smoke temperature raising section F, heating the smoke to 90 ℃ by water vapor at 110 ℃ from a generator, and then discharging the smoke from a smoke outlet section G of the desulfurizing tower.
In summary, the above embodiments of the present invention have at least the following effects compared to the prior art:
1. the submicron order fine pollutant in the flue gas is reduced by more than 80 percent, and the clean emission of the flue gas is realized. The temperature of the flue gas entering the tower can be reduced to 80-110 ℃, the flow speed of the flue gas in the desulfurizing tower is reduced, the contact time of the flue gas and the absorption washing liquid is prolonged, and the cleaning and the removal of SOx and particulate matters are facilitated. Meanwhile, the temperature of the flue gas is reduced, the evaporation of volatile substances in the solution is reduced, and the secondary generation of fine pollutants is effectively reduced.
And the temperature of the flue gas is reduced to 80-110 ℃ before entering the tower, SO that the acid dew point temperature, SO, of the flue gas is reached3Condensation occurs to promote the first growth of fine pollutants; injecting steam into the desulfurizing tower to form a supersaturated steam environment to promote the secondary growth of fine pollutants; and deep cold water is used for cooling the flue gas in the deep cooling area, so that the steam in the flue gas is promoted to be condensed by taking fine pollutants as condensation nuclei, and fine particles are promoted to be condensed for the third time. Through cubic phase transition condensation principle, impel tiny particulate matter fully to grow up, by effective desorption of washing liquid and defroster, make the tiny particulate matter in the flue gas reduce more than 80%, realize the clean emission of flue gas.
2. Effectively eliminating the white smoke phenomenon.
The high-temperature flue gas enters a desulfurizing tower, the temperature is reduced to 80-110 ℃, and the temperature of the purified flue gas after desulfurization can be reduced by 3-7 ℃; the deep cooling section can reduce the temperature of the desulfurized purified flue gas by 3-5 ℃, the temperature of the purified flue gas can be reduced by 6-12 ℃ in total, and the water content of the flue gas can be reduced by 45-75 g/kg. The temperature of the desulfurized flue gas is increased to more than 90 ℃ after being reduced, the humidity of the flue gas is reduced to 20-28% from 100%, and the phenomenon of white smoke can be effectively eliminated.
3. Realizes the emission reduction and the recycling of the desulfurization wastewater.
The heat of the flue gas entering the desulfurizing tower is utilized to evaporate the desulfurizing wastewater, and the desulfurizing wastewater is changed into water vapor to be injected into the desulfurizing tower, so that the emission reduction and the recycling of the desulfurizing wastewater are realized. The emission of the desulfurization waste water can be reduced by 10-20 g/kg of flue gas, and the waste water treatment cost is effectively reduced.
4. The cascade utilization of energy is realized, the system is simple, and the investment is low.
The split heat pump system is adopted, the heat of the high-temperature flue gas is utilized step by step, the step utilization of energy is realized, an additional heat source is not needed by the system, and the aims of greatly reducing the content of fine pollutants in the desulfurized flue gas, eliminating white smoke, reducing wastewater discharge and supplementing water to the system are fulfilled; meanwhile, the condenser part of the traditional heat pump is arranged in the desulfurizing tower of the split heat pump system, and a heat exchange type of solvent steam flowing through the pipe is adopted, so that the complexity of the whole system is greatly simplified, and the investment cost is saved.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (13)

1. A wet desulphurization system is characterized by comprising a desulphurization tower and a split heat pump system, wherein the inside of the desulphurization tower sequentially comprises a cooling absorption section, a steam injection section, a deep cooling section, a flue gas heating section and a flue gas outlet section from bottom to top;
the split type heat pump system comprises a generator, a waste water evaporator, a cryogenic evaporator, an absorber, a heat exchanger and a sulfur-containing flue gas inlet pipe communicated with a cooling absorption section of the desulfurizing tower;
the generator and the waste water evaporator are sequentially arranged along the flowing direction of the sulfur-containing flue gas inlet pipe so as to realize the continuous cooling of the sulfur-containing flue gas by the generator and the waste water evaporator;
a desulfurization waste liquid outlet at the bottom of the desulfurization tower is sequentially communicated with the absorber and the waste water evaporator, and a steam outlet of the waste water evaporator is communicated with a steam injection section of the desulfurization tower, so that the absorber and the waste water evaporator can continuously heat the desulfurization waste liquid and generate steam to be carried out in the desulfurization tower;
the generator is sequentially communicated with the heat exchanger and the absorber, so that the refrigerating fluid discharged after heat exchange of the generator can be cooled through the heat exchanger, then cooled and diluted through the absorber, then returned to the heat exchanger to exchange heat with the refrigerating fluid before dilution, heated and then fed into the generator;
the generator is communicated with a heat exchange device of a smoke temperature raising section of the desulfurizing tower, so that solvent steam generated by heating of refrigerating fluid in the generator enters the heat exchange device of the desulfurizing tower, a condensate water outlet of the heat exchange device of the smoke temperature raising section is communicated with the cryogenic evaporator, a throttling valve for cooling is further arranged between the condensate water outlet of the heat exchange device and the cryogenic evaporator, the cryogenic evaporator is further communicated with a deep cooling section of the desulfurizing tower, so that cryogenic reflux water from the deep cooling section is subjected to heat exchange with the condensate water from the smoke temperature raising section in the cryogenic evaporator and then is cooled, and then enters the deep cooling section of the desulfurizing tower, and the condensate water from the smoke temperature raising section is heated and then is gasified into steam;
and a steam outlet of the cryogenic evaporator is communicated with the absorber to dilute and cool the refrigerant liquid from the generator.
2. The wet desulfurization system of claim 1, further characterized in that a water heating channel is disposed in the absorber, and the water heating channel is provided with a normal-temperature water inlet and a heating water outlet so as to heat the normal-temperature water by the heat released from the refrigerant fluid.
3. The wet desulphurization system of claim 1, further characterized in that at least two steam injection ports are provided in the steam injection section of the desulphurization tower, and the steam injection ports are circumferentially and uniformly spaced along the same horizontal plane of the inner wall of the desulphurization tower;
the steam injection direction of each steam injection port is inclined downwards, and the steam injection direction and the inner wall surface of the desulfurizing tower form an angle of 10-60 degrees; the inclination angles of all the steam injection ports are the same.
4. The wet desulfurization system of claim 3, further characterized in that the steam injection direction of each steam injection port is 20 ° to 45 ° from the inner wall surface of the desulfurization tower.
5. The wet desulfurization system of claim 3, further characterized in that the steam injection direction of each steam injection port is 30 ° to the inner wall surface of the desulfurization tower.
6. The wet desulphurization system according to any one of claims 1 to 5, further characterized in that the desulphurization tower is further provided with a spray washing section between the steam injection section and the deep cooling section, and the bottom of the spray washing section is further provided with a return pipe communicated with the top.
7. The wet desulphurization system according to any one of claims 1 to 5, further characterized in that the desulphurization tower is further provided with a demisting section between the deep cooling section and the flue gas heating section, and the demister of the demisting section comprises any one of a water droplet separator, a baffle demister, a cyclone separator and an electrostatic demister.
8. A wet desulfurization method using the wet desulfurization system according to any one of claims 1 to 7, characterized by comprising:
enabling sulfur-containing flue gas with the temperature of more than or equal to 150 ℃ to sequentially pass through the generator and the waste water evaporator for continuous cooling, then enabling the sulfur-containing flue gas to enter a cooling absorption section of the desulfurization tower, and enabling the sulfur-containing flue gas to sequentially rise in the desulfurization tower to pass through the steam injection section, the deep cooling section, the flue gas temperature raising section and the flue gas outlet section;
introducing the desulfurization waste liquid discharged from the bottom of the desulfurization tower into the absorber to heat up, then introducing the desulfurization waste liquid into the waste water evaporator to exchange heat to generate water vapor, and introducing the generated water vapor into a vapor injection section of the desulfurization tower;
after the temperature of the rich liquid refrigerant liquid is reduced by the heat exchanger, the rich liquid refrigerant liquid is cooled and diluted by the absorber to obtain diluted refrigerant liquid, and the diluted refrigerant liquid is returned to the heat exchanger to exchange heat with the rich liquid refrigerant liquid before dilution, raise the temperature and then enter the generator;
introducing solvent steam generated by heat exchange of the refrigerating fluid in a generator into a heat exchange device of a flue gas heating section of the desulfurizing tower to heat rising flue gas, cooling condensed water generated after heat exchange through a throttle valve, then entering the cryogenic evaporator, exchanging heat with return water from the deep cooling section, heating and gasifying the condensed water into the solvent steam, cooling the return water from the deep cooling section, and then returning the cooled return water to the deep cooling section to cool the flue gas;
and introducing the solvent steam generated by the cryogenic evaporator into the absorber to dilute and cool the refrigerant liquid from the generator.
9. The wet desulphurization method according to claim 8, wherein the temperature of the sulfur-containing flue gas entering the waste water evaporator is 110-140 ℃, and the temperature of the flue gas entering the desulphurization tower is 80-110 ℃.
10. The wet desulphurization method as recited in claim 9, wherein when the desulphurization tower is provided with a spray washing section and a demisting section, the slurry at the bottom of the desulphurization tower is washed by the cooling absorption section, then flows upwards to be mixed with the steam injected by the steam injection section, enters the spray washing section for washing, is cooled by the deep cold water from the evaporator, enters the demisting section, enters the flue gas heating section for raising the temperature to more than 90 ℃, and is discharged from the flue gas outlet section of the desulphurization tower.
11. The wet desulphurization method according to any one of claims 8 to 10, wherein the cryogenic water and the flue gas in the deep cooling section adopt a direct contact spray heat exchange type or a non-contact indirect heat exchange type, the temperature of the return liquid in the deep cooling section is 20 to 40 ℃, and the temperature of the cryogenic liquid from the evaporator is 5 to 25 ℃.
12. The wet desulphurization method according to any one of claims 8 to 10, wherein the refrigerant fluid used for exchanging heat with the sulfur-containing flue gas in the generator and generating the solvent vapor comprises any one of a lithium bromide solution, ammonia water and a lithium nitrate solution.
13. The wet desulphurization method according to any one of claims 8 to 10, wherein the refrigerant fluid used for exchanging heat with the sulfur-containing flue gas in the generator and generating the solvent vapor is a lithium bromide solution.
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