CN-121971989-A - Flue gas mercury removal method and system based on metal sulfide slurry atomization injection

Abstract

The invention discloses a flue gas mercury removal method and a flue gas mercury removal system based on metal sulfide slurry atomization injection. The method comprises the steps of mixing a solution containing metal salt and a surfactant with a sulfur source solution capable of generating sulfur ions to perform precipitation reaction to obtain metal sulfide slurry, and spraying the metal sulfide slurry into a mercury-containing flue gas pipeline through atomization to convert a mercury source into mercury sulfide. The in-situ synthesized metal sulfide in the existing liquid phase adopted by the invention has the advantages of small particle size, large specific surface area, high dispersibility and strong stability, can effectively convert polymorphic mercury in the flue gas of the cement kiln into stable mercury sulfide, realizes the efficient removal of the polymorphic mercury, simultaneously avoids the problems of powder agglomeration and carbon residue, reduces the preparation and operation cost, and improves the system stability.

Inventors

• LI HAILONG
• ZHANG MINGGUANG
• MENG FANYUE
• ZHU PENGLIN
• ZHENG HAILIN

Assignees

• 中南大学

Dates

Publication Date

20260505

Application Date

20260129

Claims (10)

1. 1. A flue gas mercury removal method based on metal sulfide slurry atomization injection is characterized in that a solution containing metal salt and a surfactant is mixed with a sulfur source solution capable of generating sulfur ions to carry out precipitation reaction to obtain metal sulfide slurry, the metal sulfide slurry is atomized and injected into a flue gas pipeline containing mercury to convert a mercury source into mercury sulfide, and the metal ions in the metal salt can form water-insoluble sulfide with the sulfur ions.
2. 2. A flue gas mercury removal method based on metal sulfide slurry atomization injection as claimed in claim 1, wherein: the particle size of the metal sulfide is 10-500 nm; the solid content of the metal sulfide slurry is 0.01-5wt%.
3. 3. The method for removing mercury from flue gas based on atomization and spraying of metal sulfide slurry according to claim 1 or 2, wherein the molar ratio of metal elements in the metal salt to sulfur elements in a sulfur source solution capable of generating sulfur ions is 1:1-2.
4. 4. A flue gas mercury removal method based on metal sulphide slurry atomisation injection according to claim 1 or 2, characterised in that: the metal element in the metal salt comprises at least one of a second main group metal element, a transition metal element and a fourth main group metal element; the sulfur source capable of generating sulfur ions includes at least one of water-soluble inorganic sulfide and organic sulfur compound.
5. 5. The method for removing mercury from flue gas based on atomized spray of metal sulfide slurry according to claim 4, wherein the method comprises the following steps: the metal element in the metal salt comprises at least one of Zn, cu, fe, co, pb, ca; The water-soluble inorganic sulfide comprises at least one of ammonium sulfide, sodium sulfide and potassium sulfide; the organic sulfur compound comprises at least one of thiourea and thioacetamide.
6. 6. A flue gas mercury removal method based on metal sulfide slurry atomization injection as claimed in claim 1, wherein: The surfactant is an organic amine salt; the organic amine salt is a long-chain alkyl quaternary ammonium salt with the carbon number of 12-18.
7. 7. A flue gas mercury removal method based on metal sulfide slurry atomization injection as claimed in claim 1, wherein: The concentration of the metal salt is 0.01-1.0mol.L -1 ; the addition amount of the dispersing agent is 0.5-10wt% of the metal sulfide solid; The concentration of the sulfur source solution capable of generating sulfur ions is 0.01-2.0 mol.L -1 .
8. 8. The flue gas mercury removal method based on metal sulfide slurry atomization injection according to claim 1 is characterized in that the precipitation reaction is carried out at a temperature of 10-80 ℃, the pH value of a reaction system is 8-13, the stirring speed is 200-1500 r.min -1 , and the time is 1-60 min.
9. 9. A flue gas mercury removal method based on metal sulfide slurry atomization injection as claimed in claim 1, wherein: The mercury source comprises at least one of Hg 2+ 、Hg 0 ; the spraying amount of the atomization spraying is 0.01-10 mL/m 3 smoke; In the flue gas pipeline containing mercury, the temperature is 50-250 ℃, and the initial concentration of a mercury source is 1-500 mug.Nm -3 .
10. 10. A system for a flue gas mercury removal method based on metal sulfide slurry atomization injection according to any one of claims 1 to 9, which is characterized by comprising a slurry preparation unit and a mercury removal unit.

Description

Flue gas mercury removal method and system based on metal sulfide slurry atomization injection Technical Field The invention relates to an industrial flue gas mercury removal method, in particular to a flue gas mercury removal method based on metal sulfide slurry atomization injection, and belongs to the technical field of air pollution control. Background Mercury is highly toxic, volatile, and persistent and bioaccumulative in the environment, and is one of the pollutants that is important to control worldwide. Mercury in the cement production process is mainly discharged into the atmosphere through kiln tail flue gas, and the discharge characteristic of the mercury is obviously affected by the cement kiln process. Because of the existence of starting and stopping of a raw material mill and kiln ash returning in the novel dry clinker production process, the continuous circulation and enrichment of mercury in the flue gas lead to the simultaneous existence of multi-form mercury (mainly oxidized mercury and elemental mercury) in the kiln tail flue gas and large concentration fluctuation. Currently, cement kilns generally lack wet desulfurization or other synergistic mercury removal equipment, so that oxidized mercury (Hg 2+) cannot be effectively captured, the emission rate is generally up to 70%, and elemental mercury (Hg 0) is about 30%, exhibiting significantly different emission characteristics from metal smelters, coal-fired power plants, garbage incinerators, and the like. At present, an effective flue gas mercury pollution control means is not available in a cement kiln, and the existing general scheme has obvious defects under the specific working conditions of high temperature, high dust and complex components (high SO 2、NOx、H2 O content) of the cement kiln. Firstly, although the activated carbon spray mercury removal technology is the most mature commercial mercury removal technology at present, the technology depends on independent storage and transportation and spraying systems, the equipment structure is complex, the investment and operation cost are high, the technology is difficult to apply to industrial scenes such as cement kilns which are sensitive to cost, secondly, solid powder adsorbents such as activated carbon are often used for improving the contact probability of the solid powder adsorbents with mercury by pursuing the reduction of particle size, in the environment of high-temperature turbulence and complex components of the cement kilns, ultrafine particles are extremely easy to be driven by van der Waals force and electrostatic action to agglomerate, the effective surface exposure degree is reduced, the adsorbent utilization rate is obviously reduced, the application of the activated carbon spray mercury removal technology in the cement kilns is greatly limited, in addition, the technology breaks the mercury circulation inside the kiln system for realizing effective control, and is usually realized by periodically removing part of kiln ash and adding the kiln ash to cement products, but the activated carbon spray technology can obviously improve the carbon content in kiln ash, further adversely affect the mineral composition of cement clinker and the quality of the final products, and the applicability of the technology in the cement kilns is further limited. Therefore, the cement kiln still faces the outstanding problems that the mercury emission control difficulty is high and the emission level is difficult to reach the standard stably in actual operation as one of important sources of artificial mercury emission, on one hand, the complex high-temperature high-dust working condition aggravates the agglomeration effect of the powder adsorbent and weakens the applicability of the conventional adsorption and oxidation means, on the other hand, the simultaneous existence of Hg 2+ and Hg 0 in the flue gas brings higher requirements for the control technology in a synergic manner, and the single means aiming at mercury in a certain form are difficult to meet the overall emission reduction target. The Chinese patent publication No. CN111330427A discloses an application of a metal sulfide mercury removing agent in the aspect of removing mercury in flue gas by washing, wherein the metal sulfide mercury removing agent forms suspension in a washing device or a wet dust collector, and Hg 0 in the flue gas is converted into stable mercury sulfide to realize the washing and removing of Hg 0. However, in this method, the metal sulfide suspension is obtained by directly dispersing dried or pulverized metal sulfide powder (particle size is usually in the order of micrometers) in a liquid, and is susceptible to agglomeration, sedimentation and dispersion unevenness when in use, so that it is only suitable for application environments of 20-95 ℃ and is mainly used for spray towers in metal smelting. Therefore, there is a need to develop a novel mercury removal technology that can operate efficientl