CN113648812A - Integrated removal system and method for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet-process absorption - Google Patents

Integrated removal system and method for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet-process absorption Download PDF

Info

Publication number
CN113648812A
CN113648812A CN202110945338.4A CN202110945338A CN113648812A CN 113648812 A CN113648812 A CN 113648812A CN 202110945338 A CN202110945338 A CN 202110945338A CN 113648812 A CN113648812 A CN 113648812A
Authority
CN
China
Prior art keywords
flue gas
mercury
pipe section
gas pipeline
solution
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202110945338.4A
Other languages
Chinese (zh)
Inventor
李娜
周屈兰
檀经考
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xian Jiaotong University
Original Assignee
Xian Jiaotong University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xian Jiaotong University filed Critical Xian Jiaotong University
Priority to CN202110945338.4A priority Critical patent/CN113648812A/en
Publication of CN113648812A publication Critical patent/CN113648812A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • 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
    • B01D53/64—Heavy metals or compounds thereof, e.g. mercury
    • 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
    • B01D53/75—Multi-step processes
    • 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
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/10—Oxidants
    • B01D2251/106—Peroxides
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2259/00—Type of treatment
    • B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
    • B01D2259/804—UV light

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Treating Waste Gases (AREA)

Abstract

The invention discloses an integrated removal system and method for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet absorption. According to the invention, the atomizing nozzles are arranged in the flue gas pipeline, the hydrogen peroxide solution containing ferrous sulfate hexahydrate is sprayed, elemental mercury is efficiently converted into water-soluble divalent mercury under the action of an electrode plate electric field and an ultraviolet lamp, and then the flue gas enters the rear-end wet denitrification device, so that the mercury and nitrogen elements in the flue gas can be absorbed and removed simultaneously. The system can be modified on the existing wet denitrification process, and has the advantages of simple process flow, low investment cost, high removal efficiency, higher economic value and practical production significance.

Description

Integrated removal system and method for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet-process absorption
Technical Field
The invention relates to a method for efficiently removing mercury and nitrogen in coal-fired flue gas, in particular to a system and a method for integrally removing mercury and nitrate through photoelectric synergistic catalytic oxidation and wet-process absorption.
Background
Mercury is a heavy metal element, and is a simple substance of mercury or a compound of mercury, has strong biological toxicity, and causes various direct or indirect damages to human beings, plants and animals. The international environmental and health communities have given increasing attention to the problem of mercury hazard. The pollution source of mercury to the environment mainly comprises two aspects: natural release and man-made emission, wherein the coal burning mercury emission quantity accounts for about one third. In the course of wet desulfurization, various operating parameters are adjusted and H is used2S and a small amount of Ethylene Diamine Tetraacetic Acid (EDTA) reagent are added, so that the mercury capture efficiency of the desulfurization system can be obviously improved. Selective catalytic reduction denitration device (SCR) capable of converting NO intoxReduction to nitrogen gas N2And for elemental mercury Hg0Also has certain oxidation effect. However, these flue gas cleaning devices have limited mercury removal capability, especially for elemental mercury Hg in coal-fired flue gas0And has extremely high volatility, and can generally pass through a conventional flue gas purification device without being captured. In this view, Hg is for elemental mercury0Is critical to effecting total mercury emission control. There are many control techniques for high concentration sources of mercury, but these techniques are difficult and costly to work with low concentrations of mercury in coal-fired power plants. At present, the mercury removal technology of flue gas after combustion mainly comprises dry removal (spraying adsorbent) and wet removal (adding oxidant). The dry-method demercuration has limited efficiency and higher cost, and can influence the flow field in the boiler, so the wet-method demercuration is a better choice, and the strong oxidizing solution can be used for removing the elemental mercury Hg0Oxidized into ion mercury Hg2+And the latter is trapped in the oxidant solution, so as to avoid secondary pollution of mercury element, and then the bivalent mercury solution is reasonably treated. However, a set of wet mercury removal equipment is unacceptable for new power plants and operated power plants, both in construction sites and in investment.
At present, the construction cost of independent equipment for forced oxidation demercuration is very high, so that a wet-process demercuration method with high efficiency and economic requirements is required, the existing equipment of a power plant can be utilized, and the combined removal of mercury and other pollutants is carried out at the same time, so that the increasingly strict emission standard of pollutants in the flue gas of a coal-fired power plant is met.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a system and a method for integrated removal of mercury and nitrate by photoelectric synergistic catalytic oxidation and wet absorption, which are methods for efficiently removing mercury and nitrogen oxides in coal-fired flue gas, and are relatively reliable and efficient in removing gaseous Hg by using forced oxidation and solution absorption0And nitrogen oxides.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
an integrated removal system for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet absorption comprises a flue gas pipeline 1, a solution nozzle 2, an electrode plate 3, an ultraviolet light source 4, a positive electrode 5, a negative electrode 5, an electrochemical enrichment pool 6, a check valve 7, a circulating pump 8 and a spraying device 9;
the flue gas pipeline 1 is a main body and an attachment of the whole system, a middle vertical pipe section is connected with a straight pipe section at an inlet, a cuboid region serving as an electrochemical enrichment pool 6 is sealed at the bottom of the middle vertical pipe section, a straight pipe section at an outlet is connected with the top of the middle vertical pipe section, and the solution nozzle 2 is installed on the upper wall surface of the straight pipe section at the inlet of the flue gas pipeline 1; the electrode plates 3 are arranged on the upper wall surface and the lower wall surface of the inlet straight pipe section of the flue gas pipeline 1, and the electrode plates 3 are positioned behind the solution nozzle 2; the ultraviolet light source 4 is arranged on the upper electrode plate of the electrode plate 3; the positive and negative electrodes 5 are arranged on two side wall surfaces at the bottom of the middle vertical pipe section of the flue gas pipeline 1, and the positive and negative electrodes 5 are positioned in the electrochemical enrichment pool 6; the outlet of the electrochemical enrichment pool 6 is connected to the inlet of a circulating pump 8 through a check valve 7, the outlet of the circulating pump 8 is connected to a spraying device 9, and the spraying device 9 is positioned at the upper part of the middle vertical pipe section of the flue gas pipeline 1; the solution nozzle 2 sprays hydrogen peroxide solution containing ferrous sulfate hexahydrate into the flue gas pipeline 1, and the electrochemical enrichment pool 6 contains an oxidant.
The solution nozzle 2 dissolves hydrogen peroxide containing ferrous sulfate hexahydrateThe liquid is uniformly sprayed into the pipeline, and the Hg-containing liquid to be treated0The flue gas and the NO continue to advance together with the atomized liquid particles, flow through an electric field arranged on an electrode plate 3 behind the solution nozzle 2 and are irradiated by the ultraviolet light source 4, and the elemental mercury is efficiently catalyzed and oxidized into bivalent mercury; then the flue gas enters the middle vertical pipe section of the flue gas pipeline 1 for wet denitrification: in the electrochemical enrichment pool 6, Hg is introduced by the action of the positive and negative electrodes 52+The mercury is concentrated on the cathode and treated uniformly, and elemental mercury can be generated by direct electrolysis and recovered; the cheap oxidant solution in the electrochemical enrichment pool 6 is conveyed to a spraying device 9 through a check valve 7 and a circulating pump 8, and is sprayed from top to bottom on the upper part of the middle vertical pipe section of the flue gas pipeline 1, and the further treated Hg-containing solution is2+And NO2And a small residual proportion of Hg0The flue gas and NO go in the same direction with the atomized oxidant liquid particles, and then return to the electrochemical enrichment pool 6 after the removal is finished. After the mercury and the nitrogen are absorbed and removed by a wet method through photoelectric synergistic catalytic oxidation of elemental mercury and nitrogen, the mercury and the nitrogen are simultaneously treated and remain in a liquid phase, and finally purified flue gas is obtained.
Under the combined action of an electric field arranged on the electrode plate 3 and the irradiation of the ultraviolet light source 4, the oxidant catalyzes and oxidizes the elemental mercury, namely photoelectricity is cooperated to catalyze and oxidize.
The electric field intensity of the electrode plate 3 and the intensity of the ultraviolet light source 4 are selected between 300 and 3000 mu W/cm2 according to the concentration of the elemental mercury in the purified flue gas.
The electrochemical enrichment pool 6 contains an oxidant Ca (ClO) with the pH value of 4-62And (3) solution.
The pH value of the hydrogen peroxide solution containing the ferrous sulfate hexahydrate is 3-4.
In order to ensure the uniform dispersion and sufficient gas-liquid absorption reaction of the liquid particles in the flue gas pipeline, the solution nozzle 2 should be of a type with a large spraying angle and small atomized particles.
The operation method of the integrated removal system for the mercury and nitrate through photoelectric cooperative catalytic oxidation adopts the combination of wet absorption and removal of elemental mercury and nitrogen through photoelectric cooperative catalytic oxidation in a single system, and specifically comprises the following steps:
photoelectric concerted catalytic oxidation:
after completion of desulfurization, Hg is contained0And the flue gas with NO enters the flue gas pipeline 1, and at the moment, elemental mercury and nitric oxide which are not removed in the flue gas enter the inlet straight pipe section of the flue gas pipeline 1.
A solution nozzle 2 is arranged at the center of the top of an inlet straight pipe section of a flue gas pipeline 1 at the front end of an electrode plate 3, and hydrogen peroxide solution containing ferrous sulfate hexahydrate is sprayed into the flue gas pipeline and contacts with flue gas, so that elemental mercury in the flue gas is oxidized into bivalent mercury. Adding ammonium iron (II) sulfate hexahydrate (i.e., Fe (NH)) to hydrogen peroxide4)2·(SO4)2·6H2O) to form a Fenton solution with strong oxidizability, and the reaction equation is as follows:
Figure BDA0003216460630000041
Figure BDA0003216460630000042
iron ion catalyzed H2O2The decomposition is mainly by Fe2+ and Fe3+And mutual transformation between them. Wherein, at a pH of about 3, the ferric ion is mainly Fe (OH)2+The complex exists in an ionic form;
and after the solution nozzle 2, the electrode plates 3 arranged up and down on the inlet straight pipe section of the flue gas pipeline 1 generate an electric field, and the electric field strength is about 0.1-100 kV/cm. The micro liquid drops are easy to be subjected to electrostatic field action to generate charge separation, and by utilizing the effect, under the action of the electrostatic field, two ions with different charges can be converged towards different directions, the ion concentration at the middle part is reduced, and the reversible reaction is promoted
Figure BDA0003216460630000052
The chemical equilibrium of (A) is shifted to dissociate more OH.cndot.to generate more active oxide particles OH.cndot.. I.e. the electrostatic field can intensify H2O2Dissociate to help H2O2The dissociation reaction proceeds faster and more thoroughly. Since the electric field only helps H in the solution2O2Generates OH rather than ionizes O2Generating ozone O3Therefore, the voltage and the power consumption are low, and the energy consumption is lower than that of the ionization oxidation method. The intensity of the electric field can be adjusted by detecting the removal efficiency in use, and if the removal rate of the elemental mercury is low, the intensity of the electric field is increased, so that the full utilization of substances can be ensured, and the energy consumption can be reduced;
the inlet straight pipe section of the flue gas pipeline 1 is provided with a short wave continuous ultraviolet light source 4, and the ultraviolet light can promote H2O2Decomposition to OH, UV and Fe2+To H2O2There is a synergistic effect of the catalytic decomposition, i.e. in this case H2O2Has a decomposition rate far greater than that of Fe2+Catalysis or ultraviolet light excitation H2O2The simple addition of the decomposition rate, which is caused by the photosensitization reaction of the hydroxyl complex of ferric iron to produce. OH, is given by the following equation:
Figure BDA0003216460630000051
OH is strongly oxidizing and can trap gaseous Hg on the surface of the droplet0And carrying out an oxidation reaction:
2OH·+Hg→Hg2++2OH-
the zero-valent mercury Hg which is difficult to dissolve in the above reaction0Forced oxidation to water soluble Hg2+Thereby realizing the complete capture of the mercury element;
hg contained after desulfurization0Flue gas with NO, in the duct with injected H2O2/Fe2+After the solution is mixed, under the combined action of ultraviolet light and an electric field, a forced oxidation reaction occurs to remove most Hg0And NO to Hg2+And NO2And then, finishing the photoelectric synergistic catalytic oxidation part, and removing most of mercury simple substances;
wet absorption:
the flue gas flows out through the electrode plate 3 and then is denitrified by a wet method, a mature wet method process can be adopted to ensure the removal of NOx, and cheap oxidants Ca (ClO) can be adopted in an electrochemical enrichment pool 6 at the bottom of a middle vertical pipe section of the flue gas pipeline 12The mass concentration of the solution is controlled to be 25-35%, the solution is economical, the pH is controlled to be 4-6 in order to ensure the denitration efficiency, and the mercury simple substance can be captured.
In the process of wet denitrification, the positive and negative electrodes 5 can be arranged on two sides of the lower part of the electrochemical enrichment pool 6 and used as an electrolytic device, and reduction recovery of mercury simple substances is realized at the cathode through electrolytic absorption liquid: liquid Hg2+And NO3-In the enrichment pool, Hg is absorbed by the action of the electrodes2+The mercury is concentrated on the cathode for uniform treatment, can be directly electrolyzed to generate simple substance mercury for recycling, can also be added with sulfur element for solidification, is not discharged into the environment along with coal ash or desulfurized gypsum, and avoids secondary pollution;
the solution in the electrochemical enrichment pool 6 is conveyed by a non-return valve 7 via a circulation pump 8 to a spray device 9 located in the upper part of the middle vertical pipe section of the flue gas duct 1, where the oxidant Ca (ClO)2The solution is sprayed into the middle vertical pipe section of the flue gas duct 1, so that the further treated Hg-containing stream is obtained2+And NO2And a small residual proportion of Hg0Flue gas with NO and atomized Ca (ClO)2The liquid particles move in the same direction, and the reaction area and the reaction kinetics of wet absorption and removal are increased, so that the Hg in the flue gas which is not completely oxidized is treated0The NO undergoes further oxidation absorption.
Compared with conventional independent equipment for forced oxidation and demercuration, the integrated removal system for photoelectric synergistic catalytic oxidation and wet-process mercury and nitrate absorption combines photoelectric synergistic catalytic oxidation of elemental mercury and wet-process mercury and nitrogen absorption and removal, can utilize the existing equipment of a power plant to simultaneously carry out combined removal of mercury and other pollutants, meets increasingly strict emission standards of pollutants in flue gas of a coal-fired power station, is expected to obtain remarkable energy-saving and economic benefits, and can achieve the following beneficial effects:
(1) the invention utilizes the iron ion catalysis "Three functions of ultraviolet light excitation and electrostatic field strengthening can be used for H2O2The dissociation generates more active oxidized particles OH which contributes to the removal of elemental mercury.
(2) The invention utilizes the mature wet denitrification process, simultaneously oxidizes and absorbs the elementary substance mercury and NO in the flue gas, namely the mercury and the nitrogen are removed cooperatively, and the electrolysis process is adopted, thereby realizing the recycling of the mercury.
(3) The invention can adjust the oxidant jet quantity, the light intensity and the electric field intensity on line according to the concentration and the emission requirement of pollutants in the flue gas, thereby regulating and controlling the operation energy consumption and having better advantages on energy conservation and emission reduction.
Description of the drawings:
FIG. 1 is a schematic diagram of the system of the present invention.
The specific implementation mode is as follows:
as shown in fig. 1, an integrated removal system for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet absorption comprises a flue gas pipeline 1, a solution nozzle 2, an electrode plate 3, an ultraviolet light source 4, a positive electrode 5, a negative electrode 5, an electrochemical enrichment pool 6, a check valve 7, a circulating pump 8 and a spraying device 9;
the flue gas pipeline 1 is a main body and an attachment of the whole system, is a section of an inlet straight pipe section and is connected with a middle vertical pipe section, the bottom of the middle vertical pipe section is sealed to leave a cuboid region as an electrochemical enrichment pool, and the top of the middle vertical pipe section is connected with an outlet straight pipe section, and the shape of the middle vertical pipe section is shown in figure 1; the solution nozzle 2 is arranged on the upper wall surface of the inlet straight pipe section of the flue gas pipeline 1; the electrode plates 3 are arranged on the upper wall surface and the lower wall surface of the inlet straight pipe section of the flue gas pipeline 1, and the electrode plates 3 are positioned behind the solution nozzle 2; the ultraviolet light source 4 is arranged on the upper electrode plate of the electrode plate 3; the positive and negative electrodes 5 are arranged on two side wall surfaces at the bottom of the middle vertical pipe section of the flue gas pipeline 1, and the positive and negative electrodes 5 are positioned in the electrochemical enrichment pool 6; the electrochemical enrichment pool 6 is positioned at the bottom of the middle vertical pipe section of the flue gas pipeline 1, the outlet of the electrochemical enrichment pool 6 is connected to the inlet of the circulating pump 8 through the check valve 7, the outlet of the circulating pump 8 is connected to the spraying device 9, and the spraying device 9 is positioned at the upper part of the middle vertical pipe section of the flue gas pipeline 1. The solution nozzle 2 sprays hydrogen peroxide solution containing ferrous sulfate hexahydrate into the flue gas pipeline 1, and the electrochemical enrichment pool 6 contains an oxidant.
The invention can be used for H by using three functions of iron ion catalysis, ultraviolet light excitation and electrostatic field reinforcement2O2More active oxidized particles OH generated by dissociation contribute to the removal of elemental mercury, and a mature wet denitrification process is added to oxidize and absorb the elemental mercury and NO in the flue gas, namely the mercury and nitrogen pollutants are removed synergistically, and the mercury can be recycled by adopting an electrolysis process. The method can adjust the oxidant jet quantity, the light intensity and the electric field intensity on line according to the concentration and the emission requirement of pollutants in the flue gas, thereby regulating and controlling the operation energy consumption and having better advantages on energy conservation and emission reduction.
The invention relates to an operation method of a photoelectric synergistic catalytic oxidation mercury-nitrate integrated removal system, which combines the photoelectric synergistic catalytic oxidation elemental mercury and the wet absorption removal of mercury and nitrogen elements in a single system, and comprises the following specific operation methods:
photoelectric concerted catalytic oxidation:
hg-containing desulfurized product0And the flue gas with NO enters the flue gas pipeline 1, and at the moment, elemental mercury and nitric oxide which are not removed in the flue gas enter the inlet straight pipe section of the flue gas pipeline 1.
A solution nozzle 2 is arranged at the center of the top of an inlet straight pipe section of a flue gas pipeline 1 at the front end of an electrode plate 3, and hydrogen peroxide solution (with the pH value of about 3-4) containing ferrous sulfate hexahydrate is sprayed into the flue gas pipeline and contacts with flue gas, so that elemental mercury in the flue gas is oxidized into bivalent mercury. Adding ammonium iron (II) sulfate hexahydrate (i.e., Fe (NH)) to hydrogen peroxide4)2·(SO4)2·6H2O) to form a Fenton solution with strong oxidizability, and the reaction equation is as follows:
Figure BDA0003216460630000091
Figure BDA0003216460630000092
iron ion catalyzed H2O2The decomposition is mainly by Fe2+ and Fe3+And mutual transformation between them. Wherein, at a pH of about 3, the ferric ion is mainly Fe (OH)2+The complex exists in an ionic form;
in order to ensure the uniform dispersion and sufficient gas-liquid absorption reaction of liquid particles in the pipeline, the solution nozzle 2 is of a type with a larger spraying angle and smaller atomized particles;
after the solution nozzle 2, the electrode plates 3 with proper sizes are arranged on the upper and lower parts of the inlet straight pipe section of the flue gas pipeline 1, and the device generates a reasonable electric field with the electric field intensity of about 0.1-100 kV/cm. The micro liquid drops are easy to be subjected to electrostatic field action to generate charge separation, and by utilizing the effect, under the action of the electrostatic field, two ions with different charges can be converged towards different directions, the ion concentration at the middle part is reduced, and the reversible reaction is promoted
Figure BDA0003216460630000102
The chemical equilibrium of (A) is shifted to dissociate more OH.cndot.to generate more active oxide particles OH.cndot.. I.e. the electrostatic field can intensify H2O2Dissociate to help H2O2The dissociation reaction proceeds faster and more thoroughly. Since the electric field only helps H in the solution2O2Generates OH rather than ionizes O2Generating ozone O3Therefore, high voltage and power consumption are not needed, and the energy consumption is lower than that of the ionization oxidation method. The intensity of the electric field can be adjusted by detecting the removal efficiency in use, and if the removal rate of the elemental mercury is low, the intensity of the electric field is increased, so that the full utilization of substances can be ensured, and the energy consumption can be reduced;
the short-wave continuous ultraviolet light source 4 is arranged at the proper position of the inlet straight pipe section of the flue gas pipeline 1, and the ultraviolet light can promote H2O2OH is generated by decomposition, so that ultraviolet rays should be installed at a proper position of the pipe at the upper plate of the electrode plate 3 after the solution nozzle 2A light source. Ultraviolet light and Fe2+To H2O2There is a synergistic effect of the catalytic decomposition, i.e. in this case H2O2The decomposition rate of the catalyst is far greater than that of Fe2+ catalytic or ultraviolet light excited H2O2The simple addition of the decomposition rate, which is caused by the photosensitization reaction of the hydroxyl complex of ferric iron to produce. OH, is given by the following equation:
Figure BDA0003216460630000101
OH is strongly oxidizing and can trap gaseous Hg on the surface of the droplet0And carrying out an oxidation reaction:
2OH·+Hg→Hg2++2OH-
the zero-valent mercury Hg which is difficult to dissolve in the above reaction0Forced oxidation to water soluble Hg2+Thereby realizing the complete capture of the mercury element. Therefore, the ultraviolet light source 4 is arranged to promote the oxidation reaction of the elemental mercury, and the intensity of the ultraviolet light is 300-3000 muW/cm2) The method can be adjusted by detecting the removal efficiency, so that the requirements of energy conservation and emission reduction are met;
hg contained after desulfurization0Flue gas with NO, in the duct with injected H2O2/Fe2+After the solution is mixed, under the combined action of ultraviolet light and an electric field, a forced oxidation reaction occurs to remove most Hg0And NO to Hg2+And NO2And ending the photoelectric synergistic catalytic oxidation part, and removing most of mercury simple substances.
Wet absorption:
the flue gas flows out through the electrode plate 3 and then is denitrified by a wet method, a mature wet method process can be adopted to ensure the removal of NOx, and cheap oxidants Ca (ClO) can be adopted in an electrochemical enrichment pool 6 at the bottom of a middle vertical pipe section of the flue gas pipeline 12The mass concentration of the solution is controlled to be about 30%, the solution is economical, the pH is controlled to be about 5 in order to ensure the denitration efficiency, and the mercury simple substance can be captured.
In the process of wet denitrification, the wastewater can be placed under an electrochemical enrichment pool 6The two sides of the part are provided with a positive electrode and a negative electrode 5 which are used as electrolytic devices, the left side is a positive electrode, and the right side is a negative electrode. And (3) realizing reduction recovery of the mercury simple substance at the cathode through electrolytic absorption liquid: liquid Hg2+And NO3-In the enrichment pool, Hg is absorbed by the action of the electrodes2+The mercury is concentrated on the cathode for uniform treatment, can be directly electrolyzed to generate simple substance mercury for recycling, can also be added with sulfur element for solidification, is not discharged into the environment along with coal ash or desulfurized gypsum, and avoids secondary pollution.
The solution in the electrochemical enrichment pool 6 is conveyed by a non-return valve 7 via a circulation pump 8 to a spray device 9 located in the upper part of the middle vertical pipe section of the flue gas duct 1, where the oxidant Ca (ClO)2The solution is sprayed into the middle vertical pipe section of the flue gas duct 1, so that the further treated Hg-containing stream is obtained2+And NO2And a small residual proportion of Hg0Flue gas with NO and atomized Ca (ClO)2The liquid particles move in the same direction, and the reaction area and the reaction kinetics of wet absorption and removal are increased, so that the Hg in the flue gas which is not completely oxidized is treated0The NO undergoes further oxidation absorption.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.

Claims (8)

1. The utility model provides a photoelectricity is catalytic oxidation in coordination and integrated desorption system of wet process absorption mercury nitre which characterized in that: the device consists of a flue gas pipeline (1), a solution nozzle (2), an electrode plate (3), an ultraviolet light source (4), a positive electrode (5), a negative electrode (5), an electrochemical enrichment pool (6), a check valve (7), a circulating pump (8) and a spraying device (9);
the flue gas pipeline (1) is a main body and an attachment of the whole system, a middle vertical pipe section is connected with a straight pipe section at an inlet, a cuboid region serving as an electrochemical enrichment pool (6) is sealed at the bottom of the middle vertical pipe section, the straight pipe section at an outlet is connected with the top of the middle vertical pipe section, and the solution nozzle (2) is installed on the upper wall surface of the straight pipe section at the inlet of the flue gas pipeline (1); the electrode plates (3) are arranged on the upper wall surface and the lower wall surface of the inlet straight pipe section of the flue gas pipeline (1), and the installation positions of the electrode plates (3) are behind the solution nozzles (2); the ultraviolet light source (4) is arranged on an upper electrode plate of the electrode plate (3); the positive and negative electrodes (5) are arranged on two side wall surfaces at the bottom of the middle vertical pipe section of the flue gas pipeline (1), and the positive and negative electrodes (5) are positioned in the electrochemical enrichment pool (6); an outlet of the electrochemical enrichment pool (6) is connected to an inlet of a circulating pump (8) through a check valve (7), an outlet of the circulating pump (8) is connected to a spraying device (9), and the spraying device (9) is positioned at the upper part of the middle vertical pipe section of the flue gas pipeline (1); the solution nozzle (2) sprays hydrogen peroxide solution containing ferrous sulfate hexahydrate into the flue gas pipeline (1), and the electrochemical enrichment pool (6) contains an oxidant.
2. The integrated removal system for mercury and nitrate through photoelectricity-concerted catalytic oxidation and wet absorption as claimed in claim 1, wherein: the solution nozzle (2) uniformly sprays hydrogen peroxide solution containing ferrous sulfate hexahydrate into the flue gas pipeline, and Hg is contained in the solution to be treated0The flue gas and the liquid particles formed by atomization continue to advance together, flow through an electric field arranged on an electrode plate (3) behind the solution nozzle (2), and are irradiated by an ultraviolet light source (4), and elemental mercury is efficiently catalytically oxidized into divalent mercury; then the flue gas enters the middle vertical pipe section of the flue gas pipeline (1) for wet denitrification: hg is introduced into the electrochemical enrichment pool (6) by the action of positive and negative electrodes (5)2+The mercury is concentrated on the cathode and treated uniformly, and elemental mercury can be generated by direct electrolysis and recovered; the cheap oxidant solution in the electrochemical enrichment pool (6) is conveyed to a spraying device (9) through a check valve (7) and a circulating pump (8), the cheap oxidant solution is sprayed from top to bottom on the upper part of the middle vertical pipe section of the flue gas pipeline (1), and the Hg-containing gas is further treated2+And NO2And a small residual proportion of Hg0The flue gas and NO go in the same direction with the oxidant liquid particles formed by atomization, and return to the electrochemical enrichment pool (6) after the removal is finished.
3. The integrated removal system device for mercury and nitrate through photoelectricity-concerted catalytic oxidation as claimed in claim 1, wherein: the elemental mercury is catalyzed and oxidized by the oxidant under the combined action of the electric field arranged on the electrode plate (3) and the irradiation of the ultraviolet light source (4), namely photoelectricity is cooperated to catalyze and oxidize.
4. The integrated removal system for mercury and nitrate through photoelectricity-concerted catalytic oxidation and wet absorption as claimed in claim 1, wherein: the electrochemical enrichment pool (6) is filled with an oxidant Ca (ClO) with the pH value of 4-62And (3) solution.
5. The integrated removal system for mercury and nitrate through photoelectricity-concerted catalytic oxidation and wet absorption as claimed in claim 1, wherein: the pH value of the hydrogen peroxide solution containing the ferrous sulfate hexahydrate is 3-4.
6. The integrated removal system for mercury and nitrate through photoelectricity-concerted catalytic oxidation and wet absorption as claimed in claim 1, wherein: in order to ensure the uniform dispersion and the sufficient gas-liquid absorption reaction of the liquid particles in the flue gas pipeline, the solution nozzle (2) is of a type with a large spraying angle and small atomized particles.
7. The integrated removal system device for mercury and nitrate through photoelectricity-concerted catalytic oxidation as claimed in claim 1, wherein: the electric field intensity and the ultraviolet light source (4) intensity of the electrode plate (3) arrangement are selected between 300 and 3000 mu W/cm2 according to the concentration of the elemental mercury in the purified flue gas.
8. The operation method of the integrated removal system for mercury nitrate through photoelectricity concerted catalysis oxidation as set forth in any one of claims 1 to 7, characterized in that: the combination of photoelectric synergistic catalytic oxidation of elemental mercury and wet absorption and removal of mercury and nitrogen in a single system is as follows:
photoelectric concerted catalytic oxidation:
after completion of desulfurization, Hg is contained0And the flue gas with NO enters a flue gas pipeline (1), and the elemental mercury and the nitrogen oxide which are not removed in the flue gas enter an inlet straight pipe section of the flue gas pipeline (1).
At the electrode plate (3)) A solution nozzle (2) is arranged at the center of the top of an inlet straight pipe section of a flue gas pipeline (1), hydrogen peroxide solution containing ferrous sulfate hexahydrate is sprayed into the flue gas pipeline and contacts with flue gas, and elemental mercury in the flue gas is oxidized into bivalent mercury; adding ammonium iron (II) sulfate hexahydrate, namely Fe (NH), into hydrogen peroxide4)2·(SO4)2·6H2After O, Fenton solution is formed, and the Fenton solution has strong oxidizability, and the reaction equation is as follows:
Figure FDA0003216460620000031
Figure FDA0003216460620000032
iron ion catalyzed H2O2The decomposition is mainly by Fe2+ and Fe3+Are carried out by mutual transformation; wherein, at pH 3-4, the trivalent iron ion is mainly Fe (OH)2+The complex exists in an ionic form;
after the solution nozzle (2), electrode plates (3) which are vertically arranged on an inlet straight pipe section of the flue gas pipeline (1) generate an electric field, and the electric field intensity is 0.1-100 kV/cm; the micro liquid drops are easy to be subjected to electrostatic field action to generate charge separation, and by utilizing the effect, under the action of the electrostatic field, two ions with different charges can be converged towards different directions, the ion concentration at the middle part is reduced, and the reversible reaction is promoted
Figure FDA0003216460620000041
The chemical equilibrium of (A) is shifted to dissociate more OH.cndot.to generate more active oxide particles OH.cndot.. I.e. the electrostatic field can intensify H2O2Dissociate to help H2O2The dissociation reaction proceeds faster and more thoroughly; since the electric field only helps H in the solution2O2Generates OH rather than ionizes O2Generating ozone O3Therefore, the voltage and the power consumption are low, and the energy consumption is lowLower than the ionization oxidation method; the intensity of the electric field is adjusted by detecting the removal efficiency in use, and if the removal rate of the elemental mercury is low, the intensity of the electric field is increased, so that the full utilization of substances can be ensured, and the energy consumption can be reduced;
the short-wave continuous ultraviolet light source (4) is arranged at the straight pipe section at the inlet of the flue gas pipeline (1), and the ultraviolet light can promote H2O2Decomposition to OH, UV and Fe2+To H2O2There is a synergistic effect of the catalytic decomposition, i.e. in this case H2O2Has a decomposition rate far greater than that of Fe2+Catalysis or ultraviolet light excitation H2O2The simple addition of the decomposition rate, which is caused by the photosensitization reaction of the hydroxyl complex of trivalent iron to produce. OH, the reaction equation is:
Figure FDA0003216460620000042
OH is strongly oxidizing and captures gaseous Hg on the surface of the droplets0And carrying out an oxidation reaction:
2OH·+Hg→Hg2++2OH-
the zero-valent mercury Hg which is difficult to dissolve in the above reaction0Forced oxidation to water soluble Hg2+Thereby realizing the complete capture of the mercury element;
hg contained after desulfurization0Flue gas with NO, in the duct with injected H2O2/Fe2+After the solution is mixed, under the combined action of ultraviolet light and an electric field, a forced oxidation reaction occurs to remove most Hg0And NO to Hg2+And NO2And then, finishing the photoelectric synergistic catalytic oxidation part, and removing most of mercury simple substances;
wet absorption:
the flue gas is subjected to wet denitrification after flowing out through the electrode plate (3), a wet process is adopted to ensure the removal of NOx, a cheap oxidant Ca (ClO)2 solution with the mass concentration controlled between 25 and 35 percent is adopted in the electrochemical enrichment pool (6) at the bottom of the middle vertical pipe section of the flue gas pipeline (1), and the capture of mercury simple substance is realized;
in the process of wet denitrification, positive and negative electrodes (5) are arranged on two sides of the lower part of an electrochemical enrichment pool (6) and used as an electrolysis device, and reduction recovery of mercury simple substances is realized at a cathode through electrolytic absorption liquid: liquid Hg2+And NO3-In the enrichment pool, Hg is absorbed by the action of the electrodes2+The mercury is concentrated on the cathode and treated in a unified way, elemental mercury is directly generated by electrolysis and recovered, or sulfur element is added for solidification, and the mercury is not discharged into the environment along with coal ash or desulfurized gypsum, so that secondary pollution is avoided;
the solution in the electrochemical enrichment pool (6) is conveyed by a check valve (7) via a circulation pump (8) to a spray device (9) located at the upper part of the middle vertical pipe section of the flue gas pipeline (1), and the oxidant Ca (ClO)2 solution is sprayed into the middle vertical pipe section of the flue gas pipeline (1), so that the further treated Hg-containing solution is obtained2+And NO2And a small residual proportion of Hg0The flue gas with NO and Ca (ClO)2 liquid particles formed by atomization move in the same direction, so that the reaction area and the reaction kinetics of wet absorption and removal are increased, and Hg which is not completely oxidized in the flue gas is subjected to the reaction0The NO undergoes further oxidation absorption.
CN202110945338.4A 2021-08-17 2021-08-17 Integrated removal system and method for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet-process absorption Pending CN113648812A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110945338.4A CN113648812A (en) 2021-08-17 2021-08-17 Integrated removal system and method for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet-process absorption

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110945338.4A CN113648812A (en) 2021-08-17 2021-08-17 Integrated removal system and method for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet-process absorption

Publications (1)

Publication Number Publication Date
CN113648812A true CN113648812A (en) 2021-11-16

Family

ID=78492118

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110945338.4A Pending CN113648812A (en) 2021-08-17 2021-08-17 Integrated removal system and method for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet-process absorption

Country Status (1)

Country Link
CN (1) CN113648812A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115074164A (en) * 2022-05-07 2022-09-20 塔里木大学 Integrated cleaning and removing method for key harmful elements in hard-to-float bituminous coal
CN117298853A (en) * 2023-11-07 2023-12-29 昆明理工大学 System and method for separating and purifying mercury-containing material microwave-photooxidation cooperated mercury flue gas

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115074164A (en) * 2022-05-07 2022-09-20 塔里木大学 Integrated cleaning and removing method for key harmful elements in hard-to-float bituminous coal
CN115074164B (en) * 2022-05-07 2023-10-03 塔里木大学 Method for cleaning and removing key harmful elements in hard-to-float bituminous coal
CN117298853A (en) * 2023-11-07 2023-12-29 昆明理工大学 System and method for separating and purifying mercury-containing material microwave-photooxidation cooperated mercury flue gas

Similar Documents

Publication Publication Date Title
Wang et al. A review: Comparison of multi-air-pollutant removal by advanced oxidation processes–Industrial implementation for catalytic oxidation processes
CN102343212B (en) Denitration process combining co-oxidation of ozone and hydrogen peroxide with wet absorption
CN103706238B (en) System and method for removing SO2, NO and Hg in smoke on the basis of heterogeneous Fenton
US8383074B2 (en) Process and device for simultaneously desulfurizing and denitrating the flue gas with the seawater
CN104801178B (en) Method for simultaneously desulfurizing, denitrifying and removing mercury by combining radical pre-oxidation with wet absorption
CN113648812A (en) Integrated removal system and method for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet-process absorption
CN102068888A (en) Method for simultaneously desulfurizing and denitrating flue gas by wet method
CN102188882A (en) Integrated method for simultaneously realizing denitrification, desulfurization and heavy metal removal from flue gas, and special equipment suitable for the method
CN102274680A (en) Steamer discharge ammonia flue gas desulfurization, denitration and demisting integrated method
CN105233687A (en) Method for removing elemental mercury in coal-fired flue gas
CN203123795U (en) Flue gas denitration device using ozone oxidation method
CN113941238A (en) Integrated control method for low-temperature smoke pollutants
CN107715666B (en) Method and system for removing hydrogen sulfide by microwave activation persulfate spray induction of free radicals
CN201020334Y (en) Desulfurization denitration integrative smoke purifying device
CN102008882A (en) Fenton reagent for denitration of power plant smoke and denitration method by using the same
CN111514716A (en) Flue gas desulfurization, denitrification and demercuration purification method and equipment
KR102143514B1 (en) Equipment for simultaneous removal of nitrogen oxide and sulfur oxide
CN209530493U (en) System for industrial boiler flue gas desulfurization denitration
KR20190017475A (en) Method for Simultaneous Treating Nitrogen Oxides and Sulfur Oxides using Iron Ethylene diamine tetraacetic acid
CN105498480A (en) Ultraviolet radiation enhancement based method and device for simultaneous desulfurization, denitrification and particulate removal of pypocholoride
CN216024070U (en) Integrated removal system for mercury and nitrate through photoelectric synergistic catalytic oxidation and wet-process absorption
CN105833724B (en) Regenerated sintering flue gas synchronized desulfuring and denitrifying technique is coupled based on optical-electronic class fenton
CN104941417A (en) Flue gas treatment device and method
CN202962241U (en) Device for synergistically removing flue gas mercury
CN109647146A (en) System and method for desulfurization and denitrification of industrial boiler flue gas

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination