A flue gas treatment system using NaClO2 solution injection for gas phase oxidation to remove mercury

Abstract

The present invention provides a method for spraying NaClO 2 A flue gas treatment system for liquid gas phase oxidation mercury removal includes a flue gas system, a liquid inlet system, a reaction system and a flue gas dust removal and desulfurization system. The reaction system has a denitrification flue gas inlet, a solution inlet and a reaction flue gas outlet. The flue gas system is connected to the denitrification flue gas inlet of the reaction system to provide denitrification flue gas to the reaction system. The liquid inlet system is connected to the solution inlet of the reaction system to spray sodium chlorite solution into the reaction system. The reaction flue gas outlet of the reaction system is connected to the flue gas dust removal and desulfurization system to provide the reaction flue gas formed by oxidation with sodium chlorite to the flue gas dust removal and desulfurization system. The above-mentioned flue gas treatment system uses the liquid inlet system to spray NaClO into the reaction system. 2 The solution oxidizes the zero-valent mercury in the flue gas in the gas phase, achieving a high zero-valent mercury removal efficiency, ensuring that the mercury in the flue gas is discharged in compliance with the standards, and is environmentally friendly, clean, efficient and economical.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas treatment, and in particular to a flue gas treatment system for removing mercury by gas phase oxidation by spraying NaClO2 solution. Background Art

[0002] Coal combustion is the main source of mercury pollution in the atmospheric environment. The existence forms of mercury in coal flue gas can be divided into three types: zero-valent mercury (Hg 0 ), divalent mercury (Hg 2+ ) and particulate mercury (Hgp), among which zero-valent mercury is difficult to be removed by existing pollution control devices and can participate in atmospheric circulation in the atmosphere, making it the most difficult mercury species to remove.

[0003] At present, most of the conventional technologies for treating zero-valent mercury in coal-fired flue gas still use the original flue gas treatment system, that is, the flue gas generated by coal combustion is treated in sequence through the denitrification system, dust removal system and desulfurization system; however, the above process cannot achieve Hg 0 Capture and effective removal of Hg in flue gas 0 Direct discharge into the air will cause great damage to the natural environment, and will also directly affect the environmental protection compliance within the enterprise, and will seriously affect the economic benefits of the entire enterprise during production.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a flue gas treatment system for removing mercury by gas phase oxidation by spraying NaClO2 solution, which utilizes a liquid inlet system to spray NaClO2 solution into a reaction system to gas phase oxidize zero-valent mercury in the flue gas, thereby achieving a high zero-valent mercury removal efficiency, ensuring that mercury in the flue gas is discharged in compliance with the standards, and having environmental protection, cleanliness, high efficiency and economy.

[0006] The invention provides a flue gas treatment system for removing mercury by spraying NaClO2 solution for gas phase oxidation. The system comprises a flue gas system, a liquid inlet system, a reaction system and a flue gas dust removal and desulfurization system. The reaction system comprises a denitrification flue gas inlet, a solution inlet and a reaction flue gas outlet. The flue gas system is connected with the denitrification flue gas inlet of the reaction system to provide the denitrification flue gas to the reaction system. The liquid inlet system is connected with the solution inlet of the reaction system to spray a sodium chlorite solution into the reaction system. The reaction flue gas outlet of the reaction system is connected with the flue gas dust removal and desulfurization system to provide the reaction flue gas formed by oxidation with sodium chlorite to the flue gas dust removal and desulfurization system.

[0007] In one embodiment, the flue gas system includes a combustion system and a denitrification system, the denitrification system has a flue gas inlet and a denitrification flue gas outlet, the combustion system is connected to the flue gas inlet of the denitrification system to provide the denitrification system with flue gas generated by coal combustion, and the denitrification flue gas outlet of the denitrification system is connected to the reaction system to provide the reaction system with denitrification flue gas.

[0008] Furthermore, the combustion system is a boiler.

[0009] Furthermore, the denitration system is an SCR denitration system.

[0010] In one embodiment, the liquid inlet system includes a sodium chlorite solution tank, a liquid medicine delivery pump and a spray gun, wherein the liquid medicine delivery pump is connected to the sodium chlorite solution tank to deliver the sodium chlorite solution, and the spray gun is arranged at the end of the liquid medicine delivery pump to spray the sodium chlorite solution into the reaction system.

[0011] Furthermore, a valve and a flow meter are provided on the liquid delivery pipeline between the liquid medicine delivery pump and the reaction system.

[0012] In one embodiment, the flue gas dust removal and desulfurization system includes a dust removal system and a desulfurization system. The dust removal system is connected to the reaction flue gas outlet of the reaction system, and the desulfurization system is connected to the dust removal system through a flue gas duct.

[0013] Furthermore, the dust removal system is an ESP dust removal system.

[0014] Furthermore, the desulfurization system is a FGD desulfurization system.

[0015] Furthermore, a chimney is provided at the outlet end of the desulfurization system.

[0016] The flue gas treatment system of the present invention is provided with a liquid inlet system and a reaction system. The liquid inlet system can spray the sodium chlorite solution into the reaction system. The sodium chlorite solution is evaporated into small sodium chlorite powder and water vapor at the moment of contact with the high-temperature flue gas in the reaction system. The small sodium chlorite powder and Hg 0 A series of chemical reactions occur and generate Hg that can be removed by the subsequent desulfurization system. 2+ , so that Hg 0 The flue gas treatment system achieves a high zero-valent mercury removal efficiency, ensures that the mercury in the flue gas meets the emission standards, and is environmentally friendly, clean, efficient and economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic structural diagram of a flue gas treatment system for removing mercury by gas phase oxidation by spraying NaClO2 solution according to one embodiment of the present invention.

[0019] Description of reference numerals:

[0020] 1: Combustion system; 2: Denitrification system; 3: Sodium chlorite solution tank; 4: Liquid delivery pump; 5: Flow meter; 6: Reaction system; 7: Dust removal system; 8: Desulfurization system; 9: Chimney. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] Example

[0025] See also Figure 1 The flue gas treatment system of this embodiment that utilizes gas phase oxidation to remove mercury by spraying NaClO2 solution comprises a flue gas system, a liquid inlet system, a reaction system 6 and a flue gas dust removal and desulfurization system. The reaction system 6 has a denitrification flue gas inlet, a solution inlet and a reaction flue gas outlet. The flue gas system is connected to the denitrification flue gas inlet of the reaction system 6 to provide denitrification flue gas to the reaction system 6. The liquid inlet system is connected to the solution inlet of the reaction system 6 to spray sodium chlorite solution into the reaction system 6. The reaction flue gas outlet of the reaction system 6 is connected to the flue gas dust removal and desulfurization system to provide the reaction flue gas formed by oxidation with sodium chlorite to the flue gas dust removal and desulfurization system.

[0026] The flue gas system is mainly used to provide denitrified flue gas to the reaction system 6. There is no strict restriction on its structure, and a conventional structure in the art can be adopted. In one embodiment, the flue gas system may include a combustion system 1 and a denitrification system 2; wherein the combustion system 1 is mainly used to burn coal to generate flue gas, and the combustion system 1 may adopt a conventional combustion device such as a boiler; the denitrification system 2 is mainly used to denitrify the flue gas, and the denitrification system 2 may adopt an SCR denitrification system, etc., which is a conventional structure in the art.

[0027] It can be understood that the denitrification system 2 has a flue gas inlet and a denitrification flue gas outlet. The combustion system 1 is connected to the flue gas inlet of the denitrification system 2 to provide the denitrification system 2 with flue gas generated by coal combustion. The denitrification flue gas outlet of the denitrification system 2 is connected to the reaction system 6 to provide the reaction system 6 with denitrification flue gas.

[0028] The liquid inlet system is mainly used to spray the sodium chlorite solution into the reaction system 6, and its specific structure is not strictly limited. In one embodiment, the liquid inlet system may include a sodium chlorite solution tank 3, a liquid medicine delivery pump 4 and a spray gun (not shown), the liquid medicine delivery pump 4 is connected to the sodium chlorite solution tank 3 to deliver the sodium chlorite solution, and the spray gun is arranged at the end of the liquid medicine delivery pump 4 to spray the sodium chlorite solution into the reaction system 6. In addition, a valve and a flow meter 5 may be arranged on the liquid delivery pipeline between the liquid medicine delivery pump 4 and the reaction system 6 so as to regulate the flow of the sodium chlorite solution in the liquid delivery pipeline in real time.

[0029] The reaction system 6 mainly provides a place for the reaction between the flue gas and sodium chlorite. There is no strict restriction on its structure. Conventional reaction devices such as reaction pipes can be used. In the reaction system 6, the sodium chlorite solution sprayed in through the spray gun is evaporated into small sodium chlorite powder and water vapor at the moment of contact with the high-temperature flue gas. The small sodium chlorite powder reacts with Hg 0 A series of chemical reactions occur and generate Hg that can be removed by the subsequent desulfurization system 8 2+ , so that Hg 0 Can be fully removed.

[0030] The flue gas dust removal and desulfurization system is mainly used for dust removal and desulfurization of flue gas; specifically, the flue gas dust removal and desulfurization system may include a dust removal system 7 and a desulfurization system 8, the dust removal system 7 is connected to the reaction flue gas outlet of the reaction system 6, and the desulfurization system 8 is connected to the dust removal system 7 through a flue gas pipeline; in addition, a chimney 9 may be provided at the outlet end of the desulfurization system 8. While dust removal and desulfurization of flue gas are being performed, particulate mercury in the flue gas can be removed by the dust removal system 7, and the original Hg 2+ and Hg formed by oxidation with sodium chlorite in reaction system 6 2+ It can be removed by the desulfurization system 8, ultimately achieving standard emission of mercury in the flue gas.

[0031] There is no strict restriction on the dust removal system 7 and the desulfurization system 8 in the above flue gas dust removal and desulfurization system, and the existing processing system can be used; wherein the dust removal system 7 can be, for example, an ESP dust removal system, and the desulfurization system 8 can be, for example, an FGD desulfurization system.

[0032] When in use, at the initial trial operation of the flue gas treatment system for removing mercury by gas phase oxidation by spraying NaClO2 solution, the flue gas generated by boiler combustion at one end passes through a denitration device to remove nitrogen oxides to form denitrified flue gas, and the denitrified flue gas with a temperature of about 400°C then enters the reaction pipeline. At the other end, a liquid delivery pump 4 controls the flow rate through a flow meter 5 on the liquid delivery pipeline, and then pumps sodium chlorite solution into the reaction pipeline. A spray gun is provided at the end of the liquid inlet system, and the spray gun sprays the sodium chlorite solution into the reaction pipeline. Due to the presence of high-temperature denitrified flue gas in the reaction pipeline, the sodium chlorite solution is evaporated into two parts of small sodium chlorite powder and water vapor at the moment of being sprayed into the reaction pipeline, wherein the sodium chlorite will react with Hg 0 A series of chemical reactions occur to generate Hg that can be removed by the desulfurization system 8 2+ , thereby achieving Hg removal 0 After the trial operation is qualified, the above-mentioned flue gas treatment system using the injection of NaClO2 solution for gas phase oxidation to remove mercury can be put into normal operation procedures.

[0033] The flue gas treatment system for removing mercury by gas phase oxidation by spraying NaClO2 solution in this embodiment is provided with a liquid inlet system and a reaction system 6. The liquid inlet system can spray sodium chlorite solution into the reaction system 6. The sodium chlorite solution is evaporated into small sodium chlorite powder and water vapor at the moment of contact with high temperature flue gas in the reaction system 6. The small sodium chlorite powder and Hg 0 A series of chemical reactions occur and generate Hg that can be removed by the subsequent desulfurization system 8 2+ , so that Hg 0 The flue gas treatment system achieves a high zero-valent mercury removal efficiency, ensures that the mercury in the flue gas meets the emission standards, and is environmentally friendly, clean, efficient and economical.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flue gas treatment method for a flue gas treatment system using a gas phase oxidation system for mercury removal by spraying a NaClO2 solution, characterized in that: The flue gas treatment system includes a flue gas system, a liquid inlet system, a reaction system and a flue gas dust removal and desulfurization system. The reaction system has a denitrification flue gas inlet, a solution inlet and a reaction flue gas outlet. The flue gas system is connected to the denitrification flue gas inlet of the reaction system to provide the reaction system with denitrification flue gas at a temperature of 400°C. The liquid inlet system is connected to the solution inlet of the reaction system to spray sodium chlorite solution into the reaction system. The reaction flue gas outlet of the reaction system is connected to the flue gas dust removal and desulfurization system to provide the flue gas dust removal and desulfurization system with reaction flue gas formed by oxidation with sodium chlorite. The liquid inlet system includes a sodium chlorite inlet. A sodium chlorate solution tank, a liquid medicine delivery pump and a spray gun, the liquid medicine delivery pump is connected to the sodium chlorite solution tank to deliver the sodium chlorite solution, the spray gun is arranged at the end of the liquid medicine delivery pump to spray the sodium chlorite solution into the reaction system, the flue gas dust removal and desulfurization system comprises a dust removal system and a desulfurization system, the dust removal system is connected to the reaction flue gas outlet of the reaction system, the desulfurization system and the dust removal system are connected through a flue gas pipeline, the sodium chlorite solution sprayed by the spray gun is evaporated into small sodium chlorite powder and water vapor at high temperature at the moment of contact with the denitrification flue gas, the small sodium chlorite powder and Hg in the denitrification flue gas 0 A series of chemical reactions occur and generate Hg that can be removed by the desulfurization system. 2 + , so that Hg 0 Can be fully removed.

2. The flue gas treatment method according to claim 1, characterized in that: The flue gas system includes a combustion system and a denitrification system. The denitrification system has a flue gas inlet and a denitrification flue gas outlet. The combustion system is connected to the flue gas inlet of the denitrification system to provide the denitrification system with flue gas generated by coal combustion. The denitrification flue gas outlet of the denitrification system is connected to the reaction system to provide the reaction system with denitrification flue gas.

3. The flue gas treatment method according to claim 2, characterized in that: The combustion system is a boiler.

4. The flue gas treatment method according to claim 2, characterized in that: The denitrification system is an SCR denitrification system.

5. The flue gas treatment method according to claim 1, characterized in that: Valves and flow meters are provided on the liquid delivery pipeline between the liquid delivery pump and the reaction system.

6. The flue gas treatment method according to claim 1, characterized in that: The dust removal system is an ESP dust removal system.

7. The flue gas treatment method according to claim 1, characterized in that: The desulfurization system is a FGD desulfurization system.

8. The flue gas treatment method according to claim 1, characterized in that: A chimney is provided at the outlet end of the desulfurization system.

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