CN111265989A - Flue gas pollutant removing device and method - Google Patents

Flue gas pollutant removing device and method Download PDF

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Publication number
CN111265989A
CN111265989A CN202010217870.XA CN202010217870A CN111265989A CN 111265989 A CN111265989 A CN 111265989A CN 202010217870 A CN202010217870 A CN 202010217870A CN 111265989 A CN111265989 A CN 111265989A
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adsorbent
flue gas
unit
adsorption
mercury
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刘勇
胡小吐
钟璐
杨颖欣
胡静龄
杨森林
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Guangdong Jiade Environmental Protection Technology Co Ltd
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Guangdong Jiade Environmental Protection Technology Co Ltd
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    • B01D53/34—Chemical or biological purification of waste gases
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Abstract

The invention provides a flue gas pollutant removing device and a method, wherein the device comprises an oxidation unit, an adsorption unit and an absorption unit, wherein an outlet of the oxidation unit is connected with an inlet of the adsorption unit, and an outlet of the adsorption unit is connected with an inlet of the absorption unit;the bottom of the oxidation unit is connected with a flue gas channel and an oxidant channel, the adsorption unit is filled with a halogen modified adsorbent, and a spraying layer is arranged above the halogen modified adsorbent. The device provided by the invention can oxidize and fixedly adsorb mercury in flue gas and realize SO (sulfur oxide) by the arrangement of the oxidation and adsorption units and the selection of the modified adsorbent2Adsorption of and NOxThe oxidation and absorption of the flue gas realize the full removal of sulfur, nitrogen and mercury pollutants in the flue gas; the device has the advantages of simple structure, simple and convenient operation and low cost, and is suitable for treating various types of flue gas.

Description

Flue gas pollutant removing device and method
Technical Field
The invention belongs to the technical field of flue gas treatment, and relates to a flue gas pollutant removal device and a flue gas pollutant removal method.
Background
With the rapid development of economic society, the consumption of coal, petroleum and other energy sources is increased continuously, and SO is generated in the fuel combustion process2、NOxMany atmospheric pollutants such as dust and mercury, SO2With NOxAs a main pollution source of air pollution, the existing flue gas treatment technology usually carries out removal, but the existence of heavy metal pollutants such as mercury and the like also causes great harm to human health, and the heavy metal pollutants mainly exist in flue gas discharged by coal-fired power plants and industrial boilers and need to be removed synchronously in the flue gas treatment process.
At present, the removal of multi-component pollutants in flue gas generally comprises a wet method technology and a dry method technology, wherein the selective catalytic reduction device, a dust removal device and a wet desulfurization device are generally connected in series, the removal of mercury mainly depends on the adsorption effect of an adsorbent in front of the dust removal device, but according to the existence form of mercury in the flue gas, the mercury mainly exists in the form of gaseous element mercury, and part of mercury exists in the forms of oxidized mercury and granular mercury, so that the gaseous element mercury is difficult to remove by dust removal equipment, the removal of mercury is incomplete, the structure of the whole device is relatively complex, and the cost is relatively high; in the latter, the effect of desulfurization, denitration and demercuration is usually achieved by using an adsorbent, but the consumption of the adsorbent is large, the adsorbent is easily decomposed or denatured by the corrosion of acidic components, mixed pollutants are generated during regeneration, and the adsorbent still needs to be treated again.
CN 106823773A discloses a coal-fired flue gas demercuration method using an additive and an adsorbent, wherein the additive is added into a boiler of a coal-fired combustion system, the adsorbent is sprayed in a flue at the upstream of a dust removal device of a flue gas purification system, the additive is a bromine compound, the adsorbent is active carbon, active coke or modified active carbon carrying Br, and mercury adsorbed by the adsorbent is removed together with particles in the dust removal device; in the method, the addition of the additive easily causes the corrosion of equipment, and the dust and the adsorbent are precipitated and recovered together, so that the separation is difficult, and the subsequent application is influenced.
CN 110339701A discloses a system for removing mercury and sulfur dioxide in flue gas in a synergistic manner, the system utilizes the existing traditional flue gas desulfurization tower or washing tower, a slurry pool, an inlet flue, a slurry spraying layer, a lower washing layer, a composite adsorption catalyst layer, an upper washing layer, a demister and an outlet flue are sequentially arranged in the tower from bottom to top, a composite adsorption catalyst is fixed in the composite adsorption catalyst layer, the composite adsorption catalyst adsorbs mercury in the flue gas, simultaneously catalyzes and oxidizes sulfur dioxide in the flue gas into sulfuric acid liquid drops, and then the generated sulfuric acid liquid drops are discharged from the composite adsorption catalyst layer in a spraying and washing manner; the adsorption of the composite adsorption catalyst on mercury in the system mainly adsorbs granular mercury, and mercury in a gaseous form is easy to generate mercury-containing wastewater or is still remained in flue gas to cause incomplete mercury removal of the flue gas; the regeneration of the composite adsorption catalyst in the system is difficult, and the continuous operation is difficult.
In conclusion, for the purification of the flue gas pollutants, especially for the realization of desulfurization, denitration and demercuration together, a proper device combination is selected according to the pollutant state, the removal efficiency is improved, the device is simplified as far as possible, and the operation and device cost is reduced.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a flue gas pollutant removal device and a flue gas pollutant removal method, wherein the device realizes the oxidation and fixed adsorption of mercury in flue gas through the arrangement of an oxidation and adsorption unit, especially the selection of an adsorbent, and simultaneously completes the adsorption of sulfur oxides and the oxidation and absorption of nitrogen oxides, thereby realizing the sufficient removal of sulfur, nitrogen and mercury pollutants in the flue gas.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, the invention provides a flue gas pollutant removal device, which comprises an oxidation unit, an adsorption unit and an absorption unit, wherein an outlet of the oxidation unit is connected with an inlet of the adsorption unit, and an outlet of the adsorption unit is connected with an inlet of the absorption unit;
the bottom of the oxidation unit is connected with a flue gas channel and an oxidant channel, the adsorption unit is filled with a halogen modified adsorbent, and a spraying layer is arranged above the halogen modified adsorbent.
In the invention, the device is mainly used for removing SO in the flue gas2、NOxAnd Hg, to SO in conventional plants2、NOxThe method mainly combines demercuration into the prior device, and based on the existence form and respective properties of mercury in flue gas, the method converts gaseous element mercury into oxidized mercury as much as possible through an oxidation unit so as to facilitate subsequent adsorption treatment and complete the oxidation of low-valence nitrogen oxides in the process; in order to facilitate the solidification and adsorption of mercury, the halogen modified adsorbent is selected to combine the oxidized mercury and halogen in a fixed mode, so that the mercury is favorably and stably adsorbed, the process can also finish the adsorption of sulfur oxides, the demercuration and desulfurization are realized, and finally the oxidized nitrogen oxide is absorbed, so that the main pollutants in the flue gas are removed, and the purification efficiency is high; the device has simple structure, simple and convenient operation and low cost, and is suitable for treating various types of flue gas.
The following technical solutions are preferred technical solutions of the present invention, but not limited to the technical solutions provided by the present invention, and technical objects and advantageous effects of the present invention can be better achieved and achieved by the following technical solutions.
As a preferable embodiment of the present invention, the apparatus further comprises an oxidizing agent generating device including an ozone generating device or a plasma generating device.
Preferably, the oxidant generation means is connected to the inlet of the oxidation unit or to the flue gas channel by an oxidant channel.
In the invention, the oxidant is selected from ozone or plasma, the former has stronger oxidizability, the latter contains various active groups, which is beneficial to the full oxidation of elemental mercury and NO in the flue gas, and the oxidant can be added into the pipeline in advance, namely, mixed with the flue gas, or can be introduced into the oxidation unit and then mixed.
As a preferable technical scheme of the invention, the oxidation unit comprises a reaction tower, and a gas distribution plate is arranged above a flue gas inlet of the reaction tower.
Preferably, at least two baffle plates, for example, two, three, four or five baffle plates, are transversely arranged in the reaction tower, and the selection of the specific number is related to the size of the reaction tower, the treatment capacity of the flue gas, the addition amount of the oxidant and other factors.
Wherein, two adjacent baffling baffles set up in relative both sides for the flue gas flows in the reaction tower of inflection in oxidation process, prolongs reaction time.
In a preferred embodiment of the present invention, the adsorbent filled in the adsorption unit includes halogen-modified activated carbon and/or activated coke.
Preferably, the sorbent is loaded with a salt of a halogen, the halogen comprising chlorine and/or bromine.
In the invention, the adsorbent selects the active carbon and/or the active coke with better adsorption performance, and the adsorbent can adsorb SO by the active carbon and/or the active coke2The adsorbent has a good effect with granular mercury, but most of mercury in the flue gas is converted into oxidized mercury, and in order to enhance the adsorption of the oxidized mercury, the adsorbent is loaded with halogen salt by utilizing the reaction adsorption effect of mercury ions and halogen ions, so that the adsorption of the adsorbent to the oxidized mercury is improved.
Preferably, the spray layer intermittently washes the modified adsorbent.
In the present invention, the adsorbent adsorbs SO2Acid liquor may be formed on the surface of the adsorbent, and if the acid liquor exists for a long time, the structure and the performance of the adsorbent are damaged, and the activity of the adsorbent is difficult to recover after regeneration, so that the adsorbent is rinsed at intervals so as to wash away the surface acid liquor in time, and the service life of the adsorbent is prolonged.
Preferably, the device further comprises an adsorbent regeneration device and an adsorbent storage device, and the adsorbent outlet of the adsorption unit is sequentially connected with the adsorbent regeneration device, the adsorbent storage device and the adsorbent inlet of the adsorption unit.
In the invention, in order to avoid the problem of intermittent operation when the adsorbent is saturated after being used for a period of time and needs to be regenerated, an adsorbent regeneration device and a storage device are arranged beside the adsorption device, the adsorbent can be discharged into the regeneration device in time, and then the adsorbent in the storage device is added in time, so that the adsorption process can be continuously carried out when the adsorbent is regenerated, and the regenerated adsorbent enters the storage device for later use; in addition, the adsorbent can also be in a dynamic motion state, and is slowly moved downwards and discharged along with the adsorption, and is added after regeneration, so that the dynamic balance of adsorption and regeneration is maintained.
As a preferred embodiment of the present invention, the absorption unit includes a spray absorption tower.
Preferably, the top of the absorption unit is provided with at least one spray header, such as one, two, three or four spray headers, and the number of the spray headers is selected according to the cross section size of a spray device, the size of a single spray header, the amount of flue gas to be treated, the addition amount of spray liquid and the like.
Preferably, at least one liquid redistributor is arranged in the absorption unit, the specific quantity is selected according to the size of the spraying absorption tower and the adding amount of the spraying liquid, and the flue gas denitration efficiency is improved by redistributing the spraying liquid.
Preferably, the bottom liquid outlet and the top liquid inlet of the spray absorption tower are connected through a pipeline outside the spray absorption tower.
In the invention, a pump is arranged on the circulating pipeline outside the spraying device to recycle the spraying liquid, and when the concentration of the spraying liquid is higher, new spraying liquid can be supplemented.
As a preferable technical scheme, the device further comprises a dust removal device, and the dust removal device is arranged in front of the oxidation unit.
In the invention, because the flue gas usually contains dust, if not removed in advance, the dust is usually mixed with mercury and SO at an adsorption unit2The dust is preferably removed in advance, so that the service cycle of the adsorbent can be prolonged.
On the other hand, the invention provides a flue gas pollutant removal method, which is carried out by adopting the device and comprises the following steps:
(1) under the action of ozone or plasma, mercury and NO are subjected to oxidation reaction, mercury is changed into an oxidation state from a simple substance state, and NO is converted into high-valence nitrogen oxide;
(2) adsorbing the oxidized smoke in the step (1) by adopting a halogen modified adsorbent, and adsorbing SO2And oxidized mercury is adsorbed;
(3) and (3) absorbing the flue gas obtained in the step (2) by adopting spraying liquid to obtain purified gas.
As a preferable technical scheme of the invention, SO in the flue gas to be treated in the step (1)2The concentration of (A) is 500-2000 mg/Nm3E.g. 500mg/Nm3、750mg/Nm3、1000mg/Nm3、1200mg/Nm3、1500mg/Nm3、1800mg/Nm3Or 2000mg/Nm3And the like, but are not limited to the recited values, and other unrecited values within the numerical range are equally applicable; NOxThe concentration of (A) is 200-350 mg/Nm3E.g. 200mg/Nm3、220mg/Nm3、250mg/Nm3、280mg/Nm3、300mg/Nm3、320mg/Nm3Or 350mg/Nm3And the like, but are not limited to the recited values, and other unrecited values within the numerical range are equally applicable; the concentration of mercury is 10-40 mug/Nm3E.g. 10. mu.g/Nm3、15μg/Nm3、20μg/Nm3、25μg/Nm3、30μg/Nm3、35μg/Nm3Or 40. mu.g/Nm3And the like, but are not limited to the recited values, and other values not recited within the numerical range are also applicable.
Preferably, the temperature of the flue gas to be treated in step (1) is 100-200 ℃, such as 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃ or 200 ℃, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the amount of ozone or plasma added in step (1) is not less than the theoretical amount required for complete oxidation of elemental mercury and NO.
In the invention, for the purpose of fully oxidizing mercury and NO, the adding amount of the oxidant at least needs to be theoretically capable of completely oxidizing the mercury and NO, and the problem that the mercury and NO cannot be completely converted is considered, so that the theoretical amount is enough, excessive adding can cause waste, and the cost of raw materials is increased.
Preferably, before the oxidation reaction to be processed in the step (1), dust removal processing is performed.
In a preferred embodiment of the present invention, the halogen-modified adsorbent in step (2) comprises halogen-supported modified activated carbon and/or activated coke.
Preferably, the halogen comprises chlorine and/or bromine, supported in the form of a halogen salt.
Preferably, the halogen loading is 5 to 20 wt% of the total adsorbent, such as 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, or 20 wt%, but not limited to the recited values, and other values not recited within the range are also applicable.
Preferably, in the adsorption process in step (2), the adsorbent is washed periodically to remove the acid generated on the surface.
Preferably, the adsorbent is discharged for regeneration after being saturated in adsorption, and the stored adsorbent is added during regeneration, so that adsorption and regeneration are carried out simultaneously.
As a preferable technical scheme of the invention, the spraying liquid in the step (3) is in countercurrent contact with the flue gas for absorption.
Preferably, the spray liquid of step (3) comprises an alkaline solution.
Preferably, the spray liquid in the step (3) comprises Ca (OH)2Solutions, NaOH solutions, ammonia or Na2CO3Any one or a combination of at least two of the solutions, typical but non-limiting examples of which are: ca (OH)2Combination of solution and NaOH solution, NaOH solution and Na2CO3Combination of solutions, Ca (OH)2Solution, combination of NaOH solution and ammonia water, NaOH solution, Na2CO3Combinations of solutions and ammonia, and the like.
Preferably, the mass concentration of the spray liquid in the step (3) is 5-15 wt%, such as 5 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt% or 15 wt%, but not limited to the recited values, and other values not recited in the range of the recited values are also applicable.
Preferably, the spraying liquid in the step (3) is recycled until the saturation is reached.
Compared with the prior art, the invention has the following beneficial effects:
(1) the device provided by the invention can oxidize and fixedly adsorb mercury in flue gas and realize SO (sulfur oxide) by the arrangement of the oxidation and adsorption units and the selection of the modified adsorbent2Adsorption of and NOxThe oxidation and absorption of the sulfur, nitrogen and mercury in the flue gas realize the full removal of the sulfur, nitrogen and mercury pollutants in the flue gas, the removal rate of the sulfur can reach more than 98 percent, the removal rate of the nitrogen can reach more than 91 percent, and the removal rate of the mercury can reach more than 90 percent;
(2) the device has the advantages of simple structure, simple and convenient operation and low cost, and is suitable for treating various types of flue gas.
Drawings
Fig. 1 is a schematic structural diagram of a flue gas pollutant removal device provided in embodiment 1 of the present invention;
the device comprises a dust removal device, a 2-oxidation unit, a 3-oxidant generation device, a 4-adsorption unit, a 5-absorption unit, a 6-adsorbent regeneration device and a 7-adsorbent storage device.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.
The invention provides a flue gas pollutant removing device and a method, the device comprises an oxidation unit 2, an adsorption unit 4 and an absorption unit 5, an outlet of the oxidation unit 2 is connected with an inlet of the adsorption unit 4, and an outlet of the adsorption unit 4 is connected with an inlet of the absorption unit 5;
the bottom of the oxidation unit 2 is connected with a flue gas channel and an oxidant channel, the adsorption unit 4 is filled with a halogen modified adsorbent, and a spraying layer is arranged above the halogen modified adsorbent.
The following are typical but non-limiting examples of the invention:
example 1:
the embodiment provides a flue gas pollutant removal device, the structural schematic diagram of the device is shown in fig. 1, and the device comprises an oxidation unit 2, an adsorption unit 4 and an absorption unit 5, wherein an outlet of the oxidation unit 2 is connected with a lower inlet of the adsorption unit 4, and an upper outlet of the adsorption unit 4 is connected with an inlet of the absorption unit 5;
the bottom of the oxidation unit 2 is connected with a flue gas channel and an oxidant channel, the adsorption unit 4 is filled with a halogen modified adsorbent, and a spraying layer is arranged above the halogen modified adsorbent.
The device also comprises an oxidant generating device 3, wherein the oxidant generating device 3 comprises an ozone generating device, and the oxidant generating device 3 is connected to the flue gas channel through an oxidant channel.
The oxidation unit 2 comprises a reaction tower, and a gas distribution plate is arranged above a flue gas inlet of the reaction tower; four baffle plates are transversely arranged in the reaction tower, and the distances between the adjacent baffle plates are the same.
The adsorbent filled in the adsorption unit 3 comprises bromine-loaded modified activated carbon; the spraying layer intermittently adopts water to wash the modified adsorbent.
The device also comprises an adsorbent regeneration device 6 and an adsorbent storage device 7, wherein the adsorbent outlet of the adsorption unit 3 is sequentially connected with the adsorbent regeneration device 6, the adsorbent storage device 6 and the adsorbent inlet of the adsorption unit 3.
The absorption unit 4 comprises a spray absorption tower, and three spray headers are arranged at the top of the spray absorption tower and are arranged in a triangular shape; the middle part of the spraying absorption tower is provided with a liquid redistributor, the bottom liquid outlet and the top liquid inlet of the spraying absorption tower are connected through a pipeline outside the spraying absorption tower, and a pump is arranged on the pipeline.
The device also comprises a dust removal device 1, wherein the dust removal device 1 is arranged in front of the oxidation unit 2; the dust removing device 1 includes a cyclone.
Example 2:
the embodiment provides a flue gas pollutant removing device, which comprises an oxidation unit 2, an adsorption unit 4 and an absorption unit 5, wherein an outlet of the oxidation unit 2 is connected with a lower inlet of the adsorption unit 4, and an upper outlet of the adsorption unit 4 is connected with an inlet of the absorption unit 5;
the bottom of the oxidation unit 2 is connected with a flue gas channel and an oxidant channel, the adsorption unit 4 is filled with a halogen modified adsorbent, and a spraying layer is arranged above the halogen modified adsorbent.
The device further comprises an oxidant generating device 3, the oxidant generating device 3 comprises a plasma generating device, and the oxidant generating device 3 is connected to the inlet of the oxidation unit 2 through an oxidant passage.
The oxidation unit 2 comprises a reaction tower, and a gas distribution plate is arranged above a flue gas inlet of the reaction tower; four baffle plates are transversely arranged in the reaction tower, and the distances between the adjacent baffle plates are the same.
The adsorbent filled in the adsorption unit 3 comprises chlorine-loaded modified activated coke; the spraying layer intermittently adopts water to wash the modified adsorbent.
The device also comprises an adsorbent regeneration device 6 and an adsorbent storage device 7, wherein the adsorbent outlet of the adsorption unit 3 is sequentially connected with the adsorbent regeneration device 6, the adsorbent storage device 6 and the adsorbent inlet of the adsorption unit 3.
The absorption unit 4 comprises a spray absorption tower, and five spray headers are arranged at the top of the spray absorption tower; the heights of 1/3 and 2/3 in the spraying absorption tower are respectively provided with a liquid redistributor, the bottom liquid outlet and the top liquid inlet of the spraying absorption tower are connected through a pipeline outside the spraying absorption tower, and a pump is arranged on the pipeline.
The device also comprises a dust removal device 1, wherein the dust removal device 1 is arranged in front of the oxidation unit 2; the dust removing device 1 includes a bag type dust remover.
Example 3:
the embodiment provides a flue gas pollutant removal method, which is implemented by using the device in embodiment 1, and comprises the following steps:
(1) the flue gas to be treated is firstly subjected to dust removal treatment and then mixed with ozone to enter an oxidation unit 2, wherein SO in the flue gas to be treated2At a concentration of 1000mg/Nm3，NOxAt a concentration of 300mg/Nm3The concentration of mercury is 25 mug/Nm3The temperature of the flue gas is 150 ℃, and the adding amount of the ozone is NOxAnd 1.2 times of theoretical amount required by mercury oxidation, mercury is changed into an oxidation state from a simple substance state, and NO is converted into high-valence nitrogen oxide;
(2) adsorbing the flue gas obtained in the step (1) by adopting bromine-loaded modified activated carbon, wherein the bromine loading in the modified activated carbon accounts for 10 wt%, and SO2And oxidized mercury is adsorbed; in the adsorption process, the adsorbent is washed at regular time to remove acid generated on the surface, the adsorbent is discharged for regeneration after being adsorbed and saturated, and the stored adsorbent is added during regeneration so that adsorption and regeneration can be carried out simultaneously;
(3) the flue gas obtained in the step (2) is in countercurrent contact with 10 wt% NaOH spray liquid to absorb NOxObtaining purified gas, and circulating the spray liquidThe ring is used.
In this embodiment, after the flue gas is treated, the flue gas is treated according to SO in the purified gas2、NOxAnd mercury content, calculating to obtain SO2The removal rate of the catalyst reaches 98.2 percent, and NO is removedxThe removal rate of the mercury can reach 91.3 percent, and the removal rate of the mercury can reach 90.2 percent.
Example 4:
the embodiment provides a flue gas pollutant removal method, which is implemented by using the device in embodiment 2 and comprises the following steps:
(1) the flue gas to be treated is firstly subjected to dust removal treatment and then enters the oxidation unit 2 to be mixed with plasma, wherein SO in the flue gas to be treated2At a concentration of 500mg/Nm3，NOxAt a concentration of 200mg/Nm3The concentration of mercury is 12 mug/Nm3The temperature of the flue gas is 100 ℃, and the adding amount of the ozone is NOxAnd 1.1 times of theoretical amount required by mercury oxidation, mercury is changed into an oxidation state from a simple substance state, and NO is converted into high-valence nitrogen oxide;
(2) adsorbing the flue gas obtained in the step (1) by using modified activated coke loaded with chlorine, wherein the loading amount of bromine in the modified activated carbon is 5 wt%, and SO2And oxidized mercury is adsorbed; in the adsorption process, the adsorbent is washed at regular time to remove acid generated on the surface, the adsorbent is discharged for regeneration after being adsorbed and saturated, and the stored adsorbent is added during regeneration so that adsorption and regeneration can be carried out simultaneously;
(3) the flue gas obtained in the step (2) adopts Ca (OH) with the concentration of 5 weight percent2NO absorption by countercurrent contact of spray liquid and flue gasxAnd obtaining purified gas, wherein the spray liquid can be recycled.
In this embodiment, after the flue gas is treated, the flue gas is treated according to SO in the purified gas2、NOxAnd mercury content, calculating to obtain SO2The removal rate of the catalyst reaches 98.4 percent, and NO is removedxThe removal rate of the mercury can reach 91.0 percent, and the removal rate of the mercury can reach 90.4 percent.
Example 5:
the embodiment provides a flue gas pollutant removal method, which is implemented by using the device in embodiment 1, and comprises the following steps:
(1) the flue gas to be treated is firstly subjected to dust removal treatment and then mixed with ozone to enter an oxidation unit 2, wherein SO in the flue gas to be treated2At a concentration of 2000mg/Nm3，NOxAt a concentration of 350mg/Nm3The concentration of mercury is 35. mu.g/Nm3The temperature of the flue gas is 200 ℃, and the adding amount of the ozone is NOxAnd 1.3 times of theoretical amount required by mercury oxidation, mercury is changed into an oxidation state from a simple substance state, and NO is converted into high-valence nitrogen oxide;
(2) adsorbing the flue gas obtained in the step (1) by adopting bromine-loaded modified activated carbon, wherein the bromine loading in the modified activated carbon accounts for 20 wt%, and SO2And oxidized mercury is adsorbed; in the adsorption process, the adsorbent is washed at regular time to remove acid generated on the surface, the adsorbent is discharged for regeneration after being adsorbed and saturated, and the stored adsorbent is added during regeneration so that adsorption and regeneration can be carried out simultaneously;
(3) adopting NaOH solution and Na with the concentration of 7.5 wt% and the volume ratio of 1:1 for the smoke obtained in the step (2)2CO3Solution and flue gas countercurrent contact absorption of NOxAnd obtaining purified gas, wherein the spray liquid can be recycled.
In this embodiment, after the flue gas is treated, the flue gas is treated according to SO in the purified gas2、NOxAnd mercury content, calculating to obtain SO2The removal rate of the catalyst reaches 98.1 percent, and NO is removedxThe removal rate of the mercury can reach 91.2 percent, and the removal rate of the mercury can reach 90.0 percent.
Comparative example 1:
this comparative example provides a flue gas pollutant removal device and method, the structure of the device is as in example 1, the difference is only: the adsorption unit 4 is filled with unmodified adsorbent, and a spray layer is not arranged above the adsorbent.
The process is referred to the process in example 3, with the only difference that: and (3) adopting activated carbon for adsorption in the step (2), wherein an adsorbent is not washed in the adsorption process.
In the comparative example, due to the difference of the types of the used adsorbents and the composition of the adsorption unit devices, the adsorption capacity of the adsorbents on the oxidized mercury is weaker, and the adsorbents are easily corroded by acid to cause damage, so that part of the oxidized mercury enters the spray liquid and is easily reduced to be in a gas-phase simple substance state again to be released, the demercuration rate is influenced, and mercury pollution can be caused.
It can be seen from the above examples and comparative examples that the device of the present invention can not only oxidize and fix and adsorb mercury in flue gas, but also realize SO by the arrangement of the oxidation and adsorption units and the selection of the modified adsorbent2Adsorption of and NOxThe oxidation and absorption of the sulfur, nitrogen and mercury in the flue gas realize the full removal of the sulfur, nitrogen and mercury pollutants in the flue gas, the removal rate of the sulfur can reach more than 98 percent, the removal rate of the nitrogen can reach more than 91 percent, and the removal rate of the mercury can reach more than 90 percent; the device has the advantages of simple structure, simple and convenient operation and low cost, and is suitable for treating various types of flue gas.
The applicant states that the present invention is illustrated by the detailed apparatus and method of the present invention through the above embodiments, but the present invention is not limited to the above detailed apparatus and method, i.e. it is not meant to imply that the present invention must be implemented by the above detailed apparatus and method. It will be apparent to those skilled in the art that any modifications to the present invention, equivalents of the means for substitution and addition of means for carrying out the invention, selection of specific means, etc., are within the scope and disclosure of the invention.

Claims (10)

1. A flue gas pollutant removal device is characterized by comprising an oxidation unit, an adsorption unit and an absorption unit, wherein an outlet of the oxidation unit is connected with an inlet of the adsorption unit, and an outlet of the adsorption unit is connected with an inlet of the absorption unit;
the bottom of the oxidation unit is connected with a flue gas channel and an oxidant channel, the adsorption unit is filled with a halogen modified adsorbent, and a spraying layer is arranged above the halogen modified adsorbent.
2. The apparatus of claim 1, further comprising an oxidant generating device comprising an ozone generating device or a plasma generating device;
preferably, the oxidant generation means is connected to the inlet of the oxidation unit or to the flue gas channel by an oxidant channel.
3. The device according to claim 1 or 2, wherein the oxidation unit comprises a reaction tower, and a gas distribution plate is arranged above a flue gas inlet of the reaction tower;
preferably, at least two baffle plates are transversely arranged in the reaction tower.
4. The apparatus according to any one of claims 1 to 3, wherein the adsorbent packed in the adsorption unit comprises halogen-modified activated carbon and/or activated coke;
preferably, the sorbent is loaded with a halogen salt, the halogen comprising chlorine and/or bromine;
preferably, the spraying layer intermittently washes the modified adsorbent;
preferably, the device further comprises an adsorbent regeneration device and an adsorbent storage device, and the adsorbent outlet of the adsorption unit is sequentially connected with the adsorbent regeneration device, the adsorbent storage device and the adsorbent inlet of the adsorption unit.
5. The apparatus according to any one of claims 1 to 4, wherein the absorption unit comprises a spray absorption tower;
preferably, at least one spray header is arranged at the top of the absorption unit;
preferably, at least one liquid redistributor is arranged in the absorption unit;
preferably, the bottom liquid outlet and the top liquid inlet of the spray absorption tower are connected through a pipeline outside the spray absorption tower.
6. The apparatus according to any one of claims 1 to 5, further comprising a dust removal device, the dust removal device being disposed before the oxidation unit.
7. A method for removing flue gas pollutants by using the device of any one of claims 1 to 6, which is characterized by comprising the following steps:
(1) under the action of ozone or plasma, mercury and NO are subjected to oxidation reaction, mercury is changed into an oxidation state from a simple substance state, and NO is converted into high-valence nitrogen oxide;
(2) adsorbing the oxidized smoke in the step (1) by adopting a halogen modified adsorbent, and adsorbing SO2And oxidized mercury is adsorbed;
(3) and (3) absorbing the flue gas obtained in the step (2) by adopting spraying liquid to obtain purified gas.
8. The method according to claim 7, wherein SO in the flue gas to be treated in the step (1)2The concentration of (A) is 500-2000 mg/Nm3，NOxThe concentration of (A) is 200-350 mg/Nm3The concentration of mercury is 10-40 mu g/Nm3；
Preferably, the temperature of the flue gas to be treated in the step (1) is 100-200 ℃;
preferably, the addition amount of the ozone or the plasma in the step (1) is not less than the theoretical amount required for completely oxidizing the elemental mercury and NO;
preferably, before the oxidation reaction to be processed in the step (1), dust removal processing is performed.
9. The method of claim 7 or 8, wherein the halogen-modified sorbent of step (2) comprises halogen-loaded modified activated carbon and/or activated coke;
preferably, the halogen comprises chlorine and/or bromine, supported in the form of a halogen salt;
preferably, the loading amount of the halogen accounts for 5-20 wt% of the total amount of the adsorbent;
preferably, in the adsorption process in the step (2), the adsorbent is washed regularly to remove acid generated on the surface;
preferably, the adsorbent is discharged for regeneration after being saturated in adsorption, and the stored adsorbent is added during regeneration, so that adsorption and regeneration are carried out simultaneously.
10. The method according to any one of claims 7 to 9, wherein the spraying liquid in the step (3) is contacted with the flue gas in a counter-current manner for absorption;
preferably, the spray liquid of step (3) comprises an alkaline solution;
preferably, the spray liquid in the step (3) comprises Ca (OH)2Solutions, NaOH solutions, ammonia or Na2CO3Any one or a combination of at least two of the solutions;
preferably, the mass concentration of the spraying liquid in the step (3) is 5-15 wt%;
preferably, the spraying liquid in the step (3) is recycled until the saturation is reached.
CN202010217870.XA 2020-03-25 2020-03-25 Flue gas pollutant removing device and method Pending CN111265989A (en)

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