Low-temperature flue gas dry desulfurization and denitrification process

Abstract

The present application relates to a kind of low-temperature flue gas dry method simultaneously desulfurization and denitrification process, belong to flue gas purification technical field.The process includes the following steps: (1) low-temperature flue gas is cooled to below 70 DEG C by low-cost heat exchanger;(2) the cooled flue gas is passed into MW-EP (microwave electrodeless ultraviolet) equipment, under the synergistic effect of microwave and ultraviolet light, NO in flue gas is completely oxidized into NO2;(3) the flue gas after oxidation is passed into sodium alkali desulfurization absorption bed, using sodium carbonate absorbent simultaneously high-efficiency absorption SO2, NO2 and particulate in flue gas;(4) the treated flue gas is discharged through chimney;(5) sodium alkali desulfurization absorption bed in the replacement of sodium carbonate absorbent is regularly replaced, and the replaced scrap absorbent can be regenerated and used or directly sent to solid waste landfill for treatment as general solid waste.The present application has the advantages of low equipment investment cost, simple and reliable process, mature system equipment, low operating cost, desulfurization and denitrification efficiency is more than 90%, and is especially suitable for desulfurization and denitrification treatment of low-temperature flue gas.

Description

Technical Field

[0001] This invention relates to the field of air pollution control, specifically to a low-temperature dry flue gas desulfurization and denitrification process. Technical Background

[0002] Currently, a large amount of low-temperature flue gas (generally referring to temperatures between 100-300℃) generated during industrial production processes contains sulfur dioxide (SO2) and nitrogen oxides (NOx). X Pollutants such as sulfur dioxide and nitrogen oxides, when directly emitted, cause serious air pollution. Existing desulfurization and denitrification technologies are mainly divided into wet and dry methods. Wet desulfurization and denitrification technologies suffer from severe equipment corrosion and generate large amounts of wastewater; while traditional dry desulfurization and denitrification technologies typically require high reaction temperatures (generally above 300℃), and for low-temperature flue gas, additional heating equipment is needed, increasing energy consumption and operating costs. Therefore, developing an efficient and economical low-temperature flue gas dry desulfurization and denitrification technology is of significant practical importance. Summary of the Invention

[0003] The purpose of this invention is to replace a low-temperature dry flue gas desulfurization and denitrification process to overcome the shortcomings of the existing technology.

[0004] To achieve the above objectives, this application adopts the following technical solution:

[0005] This invention provides a low-temperature dry flue gas desulfurization and denitrification process, characterized by comprising the following steps:

[0006] (1) Reduce the temperature of flue gas to below 70°C by passing it through a low-temperature heat exchanger;

[0007] (2) The cooled flue gas is introduced into the MW-EP (microwave electrodeless ultraviolet) device. Under the synergistic effect of microwave and ultraviolet light, the NO in the flue gas is completely oxidized to NO2.

[0008] (3) The oxidized flue gas is passed into the sodium alkali absorption bed, and the SO2, NO2 and particulate matter in the flue gas are absorbed simultaneously and efficiently by sodium carbonate absorbent or sodium bicarbonate absorbent.

[0009] (4) The treated flue gas is discharged through a chimney in compliance with standards;

[0010] (5) Replace the sodium carbonate or sodium bicarbonate absorbent in the sodium alkali desulfurization bed regularly, and recycle or send the replaced waste absorbent to a solid waste landfill for disposal.

[0011] Optionally, the low-cost heat exchanger is a shell-and-tube heat exchanger or a plate heat exchanger, made of stainless steel or a corrosion-resistant alloy, with a heat exchange efficiency of not less than 85%.

[0012] Optionally, the operating conditions of the MW-EP equipment are: microwave power of 1-120kW, ultraviolet wavelength of 185-254nm, and oxidation reaction temperature of 50-70℃.

[0013] Optionally, the sodium carbonate absorbent in the sodium alkali desulfurization absorption bed has a particle size of 0.5-5 mm, a bed height of 0.5-2 m, and an absorption reaction temperature of 50-70 °C.

[0014] Optionally, the absorbent replacement cycle of the sodium alkali desulfurization absorption bed is 1-6 months, with the specific replacement cycle dynamically adjusted according to the concentrations of SO2 and NO2 in the flue gas, wherein the SO2 concentration exceeds 2000 mg / m³. 3 Or NO2 concentration exceeding 1000 mg / m³ 3 In this case, the replacement cycle can be shortened to less than one month.

[0015] Optionally, the regeneration method for the waste absorbent includes the following steps:

[0016] (1) Wash the waste absorbent with water to remove the particulate matter attached to the surface;

[0017] (2) Dry the washed absorbent at 80-120℃ and grind it to a particle size of 0.5-5mm;

[0018] (3) The regenerated absorbent is reused in the sodium alkali desulfurization absorption bed. Optionally, the process is suitable for desulfurization and denitrification treatment of industrial flue gas from coal-fired power plants, steel plants, cement plants, etc., with SO2 concentrations in the flue gas ranging from 100 to 5000 mg / m³. 3 NOx concentration range: 100-3000 mg / m³ 3 After treatment, the emission concentrations of SO2 and NOx in the flue gas were both below 50 mg / m³. 3 .

[0019] On the other hand, this application provides a system for the aforementioned low-temperature flue gas dry simultaneous desulfurization and denitrification process, the system comprising:

[0020] (1) Low-cost heat exchangers for cooling low-temperature flue gas to below 70°C;

[0021] (2) MW-EP equipment, used to oxidize NO in flue gas to NO2;

[0022] (3) Sodium alkali desulfurization absorption bed, used to absorb SO2, NO2 and particulate matter in flue gas; (4) Chimney, used to discharge treated flue gas;

[0023] (5) Absorbent replacement device, used to replace sodium carbonate or sodium bicarbonate absorbent in the sodium alkali desulfurization absorption bed at regular intervals.

[0024] Optionally, the MW-EP device includes a microwave source, an ultraviolet lamp, and a reaction chamber, wherein the power of the microwave source is 1-120kW, the wavelength of the ultraviolet lamp is 185-254nm, and the material of the reaction chamber is high-temperature resistant quartz glass or stainless steel.

[0025] Optionally, the sodium alkali desulfurization absorption bed includes a multi-layer packing structure, the packing being sodium carbonate particles or sodium bicarbonate particles with a particle size of 0.5-5mm, the bed height being 0.5-2m, and a gas distributor being provided at the bottom of the bed for uniformly distributing the flue gas.

[0026] The beneficial effects of this invention are:

[0027] This invention provides a low-temperature dry flue gas desulfurization and denitrification process, characterized by comprising the following steps:

[0028] (1) Reduce the temperature of flue gas to below 70°C by passing it through a low-temperature heat exchanger;

[0029] (2) The cooled flue gas is introduced into the MW-EP (microwave electrodeless ultraviolet) device. Under the synergistic effect of microwave and ultraviolet light, the NO in the flue gas is completely oxidized to NO2.

[0030] (3) The oxidized flue gas is passed into the sodium alkali absorption bed, and the SO2, NO2 and particulate matter in the flue gas are absorbed simultaneously and efficiently by sodium carbonate absorbent or sodium bicarbonate absorbent.

[0031] (4) The treated flue gas is discharged through a chimney in compliance with standards;

[0032] The sodium carbonate absorbent in the sodium alkali desulfurization bed should be replaced regularly, and the replaced waste absorbent should be recycled or sent to a solid waste landfill for disposal.

[0033] The desulfurization and denitrification technology of this invention can efficiently remove sulfur dioxide and nitrogen oxides from flue gas at low temperatures of 30-250℃ without the need for additional heating equipment, thus reducing energy consumption and operating costs. It can be widely applied in the field of desulfurization and denitrification. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a process flow diagram of a low-temperature flue gas dry desulfurization and denitrification process according to an embodiment of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the novel embodiments of the present invention clearer, the technical solutions of the novel embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the novel embodiments of the present invention, and not all embodiments. The components of the novel embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the novel embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0038] It should be noted that similar labels and letters in the following figures indicate similar items, therefore,

[0039] Once an item is defined in one of the accompanying figures, it does not need to be further defined and explained in subsequent figures.

[0040] In the description of this novel invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this novel invention is in use. They are used only for the convenience of describing this novel invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this novel invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0041] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0042] In the description of this novel invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this novel invention based on the specific circumstances.

[0043] The following is combined Figure 1 The technical solution of the present invention will be described.

[0044] like Figure 1 As shown, this paper discloses a low-temperature dry flue gas desulfurization and denitrification process, characterized by comprising the following steps:

[0045] (1) Reduce the temperature of flue gas to below 70°C by passing it through a low-temperature heat exchanger;

[0046] (2) The cooled flue gas is introduced into the MW-EP (microwave electrodeless ultraviolet) device. Under the synergistic effect of microwave and ultraviolet light, the NO in the flue gas is completely oxidized to NO2.

[0047] (3) The oxidized flue gas is passed into the sodium alkali absorption bed, and the SO2, NO2 and particulate matter in the flue gas are absorbed simultaneously and efficiently by sodium carbonate absorbent or sodium bicarbonate absorbent.

[0048] (4) The treated flue gas is discharged through a chimney in compliance with standards;

[0049] (5) Replace the sodium carbonate or sodium bicarbonate absorbent in the sodium alkali desulfurization bed regularly, and recycle or send the replaced waste absorbent to a solid waste landfill for disposal.

[0050] Furthermore, the low-cost heat exchanger is a shell-and-tube heat exchanger or a plate heat exchanger, made of stainless steel or a corrosion-resistant alloy, with a heat exchange efficiency of not less than 85%.

[0051] Furthermore, the operating conditions of the MW-EP equipment are as follows: the microwave source is one or more, the microwave power is 1-120kW, the ultraviolet wavelength is 185-254nm, and the oxidation reaction temperature is 50-70℃.

[0052] Furthermore, the sodium carbonate absorbent or sodium bicarbonate absorbent in the sodium alkali desulfurization absorption bed has a particle size of 0.5-5 mm, a bed height of 0.5-2 m, and an absorption reaction temperature of 50-70 °C.

[0053] Furthermore, the absorbent replacement cycle of the sodium alkali desulfurization absorption bed is 1-6 months, with the specific replacement cycle dynamically adjusted according to the concentrations of SO2 and NO2 in the flue gas, where the SO2 concentration exceeds 2000 mg / m³. 3 Or NO2 concentration exceeding 1000 mg / m³ 3 In this case, the replacement cycle can be shortened to less than one month.

[0054] Furthermore, the regeneration method for the waste absorbent includes the following steps:

[0055] (1) Wash the waste absorbent with water to remove the particulate matter attached to the surface;

[0056] (2) Dry the washed absorbent at 80-120℃ and grind it to a particle size of 0.5-5mm;

[0057] (3) The regenerated absorbent is put back into the sodium alkali desulfurization absorption bed for use.

[0058] Furthermore, the process is applicable to the desulfurization and denitrification treatment of industrial flue gas from coal-fired power plants, steel plants, cement plants, etc., with SO2 concentrations in the flue gas ranging from 100 to 5000 mg / m³. 3 NOx concentration range: 100-3000 mg / m³ 3 After treatment, the emission concentrations of SO2 and NOx in the flue gas were both below 50 mg / m³. 3 .

[0059] This invention also discloses a system for the aforementioned low-temperature flue gas dry simultaneous desulfurization and denitrification process, the system comprising:

[0060] (1) Low-cost heat exchangers for cooling low-temperature flue gas to below 70°C;

[0061] (2) MW-EP equipment, used to oxidize NO in flue gas to NO2;

[0062] (3) Sodium alkali desulfurization absorption bed, used to absorb SO2, NO2 and particulate matter in flue gas; (4) Chimney, used to discharge treated flue gas;

[0063] (5) Absorbent replacement device, used to replace the sodium carbonate absorbent in the sodium alkali desulfurization absorption bed at regular intervals.

[0064] Furthermore, the MW-EP device includes a microwave generator, an ultraviolet lamp, and a reaction chamber, wherein the power of the microwave generator is 1-10kW, the wavelength of the ultraviolet lamp is 185-254nm, and the material of the reaction chamber is high-temperature resistant quartz glass or stainless steel.

[0065] Furthermore, the sodium alkali desulfurization absorption bed includes a multi-layer packing structure, the packing is sodium carbonate particles with a particle size of 0.5-5mm, the bed height is 0.5-2m, and a gas distributor is provided at the bottom of the bed for uniformly distributing flue gas.

[0066] In another embodiment of the present invention, the process and system described herein are used to treat the waste gas from a steel plant. The gas conditions at the steel plant are low-temperature flue gas with a temperature of 90-120°C and a sulfur dioxide concentration of 800 mg / m³. 3 The concentration of nitrogen oxides is 300 mg / m³ 3 .

[0067] Low-temperature flue gas is introduced into the desulfurization and denitrification reactor, and the flow rate of the flue gas is controlled at 0.5-1 m / s, so that the residence time of the flue gas in the reactor is 1-10 seconds.

[0068] After desulfurization and denitrification reactions, the sulfur dioxide concentration in the flue gas was reduced to 30 mg / m³. 3 Below, the nitrogen oxide concentration is reduced to 50 mg / m³. 3 The desulfurization efficiency reaches over 95%, and the denitrification efficiency reaches over 90%.

[0069] This invention provides 1. a low-temperature dry flue gas desulfurization and denitrification process, characterized by comprising the following steps:

[0070] (1) Reduce the temperature of flue gas to below 70°C by passing it through a low-temperature heat exchanger;

[0071] (2) The cooled flue gas is introduced into the MW-EP (microwave electrodeless ultraviolet) device. Under the synergistic effect of microwave and ultraviolet light, the NO in the flue gas is completely oxidized to NO2.

[0072] (3) The oxidized flue gas is passed into the sodium alkali absorption bed, and the SO2, NO2 and particulate matter in the flue gas are efficiently absorbed by sodium carbonate absorbent or sodium bicarbonate absorbent.

[0073] (4) The treated flue gas is discharged through a chimney in compliance with standards;

[0074] (5) Replace the sodium carbonate or sodium bicarbonate absorbent in the sodium alkali desulfurization bed regularly, and recycle or send the replaced waste absorbent to a solid waste landfill for disposal.

[0075] This invention has the advantages of low equipment investment cost, simple and reliable process, mature system equipment and low operating cost. The desulfurization and denitrification efficiency exceeds 90%, and it is particularly suitable for desulfurization and denitrification treatment of low temperature flue gas.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-temperature dry flue gas desulfurization and denitrification process, characterized in that, Includes the following steps: (1) Cool the low-temperature flue gas to below 70°C by passing it through a low-cost heat exchanger; (2) The cooled flue gas is introduced into the MW-EP (microwave electrodeless ultraviolet) device. Under the synergistic effect of microwave and ultraviolet light, the NO in the flue gas is completely oxidized to NO2. (3) The oxidized flue gas is passed into the sodium alkali absorption bed, and the SO2, NO2 and particulate matter in the flue gas are absorbed simultaneously and efficiently by sodium carbonate absorbent or sodium bicarbonate absorbent. (4) The treated flue gas is discharged through a chimney in compliance with standards; (5) Replace the sodium carbonate or sodium bicarbonate absorbent in the sodium alkali desulfurization bed regularly, and recycle or send the replaced waste absorbent to a solid waste landfill for disposal.

2. The low-temperature dry flue gas simultaneous desulfurization and denitrification process according to claim 1, characterized in that, The low-cost heat exchanger is a shell-and-tube heat exchanger or a plate heat exchanger, made of stainless steel or corrosion-resistant alloy, with a heat exchange efficiency of not less than 85%.

3. The low-temperature dry flue gas simultaneous desulfurization and denitrification process according to claim 1, characterized in that, The operating conditions of the MW-EP equipment are as follows: the equipment includes one or more microwave sources with a power of 1-120kW, an ultraviolet wavelength of 185-254nm, and an oxidation reaction temperature of 50-70℃.

4. The low-temperature dry flue gas simultaneous desulfurization and denitrification process according to claim 1, characterized in that, The sodium carbonate or sodium bicarbonate absorbent in the sodium alkali desulfurization absorption bed has a particle size of 0.5-5 mm, a bed height of 0.5-2 m, and an absorption reaction temperature of 50-70℃.

5. The low-temperature dry flue gas simultaneous desulfurization and denitrification process according to claim 1, characterized in that, The absorbent replacement cycle of the sodium alkali desulfurization absorption bed is 1-6 months, with the specific replacement cycle dynamically adjusted according to the concentrations of SO2 and NO2 in the flue gas, where the SO2 concentration exceeds 2000 mg / m³. 3 Or NO2 concentration exceeding 1000 mg / m³ 3 In this way, the replacement cycle can be shortened to less than one month.

6. The low-temperature dry flue gas simultaneous desulfurization and denitrification process according to claim 1, characterized in that, The regeneration method for the waste absorbent includes the following steps: (1) Wash the waste absorbent with water to remove the particulate matter attached to the surface; (2) Dry the washed absorbent at 80-120℃ and grind it to a particle size of 0.5-5mm; (3) The regenerated absorbent is put back into the sodium alkali desulfurization absorption bed for use.

7. The low-temperature dry flue gas simultaneous desulfurization and denitrification process according to claim 1, characterized in that, The process described is applicable to the desulfurization and denitrification treatment of industrial flue gas from coal-fired power plants, steel plants, cement plants, etc., where the SO2 concentration in the flue gas ranges from 100 to 5000 mg / m³. 3 NOx concentration range: 100-3000 mg / m³ 3 After treatment, the emission concentrations of SO2 and NOx in the flue gas were both below 50 mg / m³. 3 .

8. A system for implementing the low-temperature dry flue gas simultaneous desulfurization and denitrification process according to any one of claims 1-7, characterized in that, include: (1) Low-cost heat exchangers for cooling low-temperature flue gas to below 70°C; (2) MW-EP equipment, used to oxidize NO in flue gas to NO2; (3) Sodium alkali desulfurization absorption bed, used to absorb SO2, NO2 and particulate matter in flue gas; (4) Chimney, used to discharge treated flue gas; (5) Absorbent replacement device, used to replace the sodium carbonate absorbent in the sodium alkali desulfurization absorption bed at regular intervals.

9. The system according to claim 8, characterized in that, The MW-EP device includes a microwave generator, an ultraviolet lamp, and a reaction chamber. The microwave generator has a power of 1-120kW, the ultraviolet lamp has a wavelength of 185-254nm, and the reaction chamber is made of high-temperature resistant quartz glass or stainless steel.

10. The system according to claim 8, characterized in that, The sodium alkali desulfurization absorption bed includes a multi-layer packing structure. The packing is sodium carbonate or sodium bicarbonate particles with a particle size of 0.5-5 mm. The bed height is 0.5-2 m. A gas distributor is provided at the bottom of the bed to uniformly distribute the flue gas.

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