A system and method for removing sulfur trioxide and ammonia from flue gas

Abstract

This invention belongs to the field of flue gas treatment technology in the atmospheric environment, specifically relating to a system and method for removing SO3 and NH3 from flue gas. The system includes a denitrification device, an air preheater, and a desulfurization tower connected sequentially through a flue along the flue gas flow direction; and a desulfurization wastewater treatment unit, a sulfonation compound agent solution preparation device, and a spray gun connected sequentially to the desulfurization tower. The sulfonation compound agent solution preparation device is used to mix the sulfonation compound agent with the clarified desulfurization wastewater to obtain a sulfonation compound agent solution. The nozzle of the spray gun is located between the denitrification device and the air preheater and is disposed within the flue, used to atomize the sulfonation compound agent solution with compressed air. Using the system described in this invention, SO3 removal efficiency can reach over 30%, and NH3 removal efficiency can reach over 10%. Furthermore, this method is unaffected by the denitrification system, produces no secondary pollution, and can simultaneously achieve synergistic treatment of desulfurization wastewater.

Description

Technical Field

[0001] This invention relates to the field of flue gas treatment technology in the atmospheric environment, specifically to a system and method for removing SO3 and NH3 from flue gas, and more specifically to a system and method for synergistically removing SO3 and NH3 from high-temperature flue gas using desulfurization wastewater. Background Technology

[0002] Currently, after ultra-low emission retrofitting of coal-fired power plants, most pollutants have been effectively controlled. However, some power plant chimneys still exhibit blue plumes. These plumes are mainly due to high concentrations of SO3 aerosols or sulfuric acid aerosols in the flue gas. SO3 and sulfuric acid aerosols primarily originate from boiler combustion and the oxidation process of flue gas denitrification catalysts. During flue gas denitrification, the catalyst can oxidize some SO2 in the flue gas to SO3. Water vapor in the flue gas interacts with SO3 to generate acidic gases such as H2SO4 vapor, which condense on the flue walls and heat exchange elements, severely corroding the flue and air preheater heat exchange elements. The generated SO3 or sulfuric acid aerosols not only easily carry heavy metals and viruses, making them a major component of acid rain, but also significantly enhance and promote the formation of smog.

[0003] The existing SO3 removal processes for coal-fired power units in China mostly involve injecting alkaline solutions into the flue gas to adsorb and neutralize the SO3, achieving good SO3 removal results. However, this process can easily lead to high fly ash adhesion, caking, and scaling and ash accumulation in the flue, affecting unit efficiency and safety.

[0004] The existing methods for controlling NH3 in flue gas from coal-fired power units in China are mostly to reduce the total amount of ammonia or urea solution injected by the SCR unit, or to use intelligent control methods for precise control and multi-point injection volume adjustment, or to use the method of adding catalytic devices / catalysts to control the NH3 content in flue gas. However, all of these methods have the problem of ammonia escape caused by changes in boiler load, coal quality, flow field, and incomplete catalysis. The existing NH3 emission control methods cannot be separated from the influence of the SCR system. Moreover, in order to ensure that the NOx emission of coal-fired power units meets the standards, the NH3 in the flue gas is in slight excess. Summary of the Invention

[0005] The purpose of this invention is to address the problems of low removal efficiency and safety of existing technologies for SO3 and NH3 removal from high-temperature flue gas, susceptibility to the influence of the denitrification system during the removal process, and the slight excess of NH3 in the treated flue gas. Therefore, this invention proposes a system and method for removing SO3 and NH3 from flue gas. This system first mixes a specific sulfonated composite agent with clarified desulfurization wastewater from a desulfurization wastewater treatment unit to form a sulfonated composite agent solution. Then, a spray gun is installed before the air preheater after the denitrification unit. The spray gun mixes and atomizes the sulfonated composite agent solution with compressed air. Finally, the atomized product is introduced into the flue to fully contact the high-temperature flue gas. Using this system, SO3 and NH3 can be simultaneously removed from high-temperature flue gas, achieving a removal efficiency of over 30% for SO3 and over 10% for NH3. Furthermore, this method is unaffected by the denitrification system, produces no secondary pollution, and can simultaneously treat desulfurization wastewater.

[0006] To achieve the above objectives, the first aspect of the present invention provides a system for removing SO3 and NH3 from flue gas. This system includes a denitrification device, an air preheater, and a desulfurization tower connected sequentially through a flue along the flue gas flow direction, and a desulfurization wastewater treatment unit, a sulfonation compound agent solution preparation device, and a spray gun connected sequentially to the desulfurization tower. The sulfonation compound agent solution preparation device is used to mix a sulfonation compound agent containing aromatic compounds and carboxymethyl cellulose with clarified desulfurization wastewater from the desulfurization wastewater treatment unit to obtain a sulfonation compound agent solution. The nozzle of the spray gun is located between the denitrification device and the air preheater and is disposed within the flue, for atomizing the sulfonation compound agent solution from the sulfonation compound agent solution preparation device with compressed air.

[0007] Preferably, the spray gun is a dual-fluid atomizing spray gun.

[0008] Preferably, the system further includes an online NH3 content detector located between the denitrification device and the spray gun, for detecting the NH3 content in the flue gas.

[0009] Preferably, the system further includes an online SO3 content detector located between the spray gun and the air preheater for detecting the SO3 content in the flue gas.

[0010] Preferably, the desulfurization wastewater treatment unit includes a triple system and a clarification device connected in sequence, wherein the clarification device is connected to the sulfonation compound agent solution preparation device.

[0011] Preferably, the system further includes a dust collector and a fan arranged sequentially on the flue, wherein the dust collector is connected to the air preheater and the fan is connected to the desulfurization tower.

[0012] A second aspect of this invention provides a method for removing SO3 and NH3 from flue gas, the method comprising the following steps:

[0013] S1. The clarified desulfurization wastewater from the desulfurization wastewater treatment unit is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device to obtain the sulfonation compound agent solution.

[0014] S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun, and then the atomized product is introduced into the flue to treat the flue gas.

[0015] The sulfonated compound contains aromatic compounds and carboxymethyl cellulose.

[0016] Preferably, the weight ratio of the aromatic compound to the carboxymethyl cellulose is 1-2:1.

[0017] Preferably, the aromatic compound is an alkylphenyl polyoxyethylene ether and / or an alkylbenzene sulfonate. More preferably, the aromatic compound is selected from one or more of polyethylene glycol octylphenyl ether, sodium dodecylbenzene sulfonate, and sodium hexadecylbenzene sulfonate.

[0018] Preferably, the solid-liquid ratio of the sulfonation compound to the clarified desulfurization wastewater is 1g:1000-2000mL.

[0019] Preferably, the particle size of the atomized product is 50-60 μm.

[0020] Preferably, in step S2, the spray volume of the atomized product is 2-3.5m. 3 / h.

[0021] Preferably, the flow rate of the flue gas is 800,000-1,200,000 m³ / h. 3 / h.

[0022] Preferably, the flue gas contains 40.29-178.57 mg / m³ 3 SO3, 1.3-3 mg / m³ 3 NH3.

[0023] Preferably, the temperature of the flue gas is 300-400°C.

[0024] Preferably, the pressure of the compressed air is 0.3-0.4 MPa, and the flow rate is 5-10 m³ / s. 3 / min.

[0025] Through the above technical solution, the present invention has at least the following beneficial effects:

[0026] (1) In the system described in this invention, a specific sulfonation compound agent is mixed with the clarified desulfurization wastewater to form a sulfonation compound agent solution. The sulfonation compound agent solution is then sprayed into the high-temperature flue in the form of atomized droplets through a spray gun to achieve effective removal of SO3 and NH3 from the flue gas, so that the removal efficiency of SO3 reaches more than 30% and the removal efficiency of NH3 reaches more than 10%.

[0027] (2) In the system described in this invention, SO3 and NH3 in the flue gas of coal-fired power units are treated in synergistic treatment with desulfurization wastewater to achieve "waste treatment with waste". This achieves the effect of simultaneous treatment of SO3 and NH3 in desulfurization wastewater and flue gas, effectively avoiding the generation of (NH4)HSO4 in the low-temperature section of the air preheater, reducing the blockage and corrosion of the air preheater, increasing the heat exchange efficiency of the air preheater heat exchange elements, reducing the pressure difference of the air preheater, reducing the frequency of steam soot blowing in the air preheater by 5%, and reducing the cumulative monthly pressure rise of the air preheater by more than 100 Pa / month, extending the life and maintenance cycle of the air preheater, solving the problems of blue plumes and acid rain caused by excessive SO3 emissions, and solving the problems of ammonia escape and emission control caused by the ultra-low emissions of the denitrification unit SCR, as well as the problems of difficult and expensive end-of-pipe treatment of desulfurization wastewater.

[0028] (3) In the system described in this invention, in a preferred case, by setting up an online NH3 content detector and an online SO3 content detector in the system respectively, and flexibly adjusting the spray volume of the spray gun according to the unit load fluctuation, intelligent control is achieved, thereby effectively controlling the emission of SO3 and NH3. The system is not affected by the denitrification device.

[0029] (4) Compared with the prior art, the system described in this invention has the advantages of simple process, mature technology, low cost, low energy consumption, low operating cost, convenient processing and simple operation. Moreover, the system control can be unattended and does not generate new pollutants. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of a system for removing SO3 and NH3 from flue gas according to an embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures

[0032] 1. Desulfurization wastewater treatment unit; 2. Sulfonation compound agent solution preparation device; 3. Spray gun; 4. Denitrification device; 5. Air preheater; 6. Online NH3 content detector; 7. Online SO3 content detector; 8. Desulfurization tower; 9. Tri-system; 10. Clarification device; 11. Dust collector; 12. Fan. Detailed Implementation

[0033] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0034] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0035] In the description of this application, unless otherwise expressly specified and limited, the terms "connected" and "linked" 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, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0036] The first aspect of this invention proposes a system for removing SO3 and NH3 from flue gas, such as... Figure 1 As shown, the system includes a denitrification device 4, an air preheater 5, and a desulfurization tower 8 connected sequentially through a flue along the flue gas flow direction, and a desulfurization wastewater treatment unit 1, a sulfonation compound agent solution preparation device 2, and a spray gun 3 connected sequentially to the desulfurization tower 8. The sulfonation compound agent solution preparation device 2 is used to mix a sulfonation compound agent containing aromatic compounds and carboxymethyl cellulose with the clarified desulfurization wastewater from the desulfurization wastewater treatment unit 1 to obtain a sulfonation compound agent solution. The nozzle of the spray gun 3 is located between the denitrification device 4 and the air preheater 5 and is disposed in the flue, and is used to atomize the sulfonation compound agent solution from the sulfonation compound agent solution preparation device 2 with compressed air.

[0037] In the system described in this invention, in a specific embodiment, the denitrification device 4 can be a conventional choice in the art. In a specific implementation, the flue gas generated by the coal-fired boiler is transported to the denitrification device 4 through a flue for denitrification treatment.

[0038] In the system described in this invention, in a specific embodiment, the air preheater 5 can be a conventional choice in the art. In a specific implementation, the flue gas treated by the denitrification device 4 is preheated in the air preheater 5 to achieve the purpose of heating the air.

[0039] In the system described in this invention, in a specific embodiment, the desulfurization tower 8 is connected to the chimney, and the flue gas is desulfurized through the desulfurization tower 8 and then discharged through the chimney.

[0040] In the system described in this invention, in a specific embodiment, the desulfurization wastewater treatment unit 1 includes a triple system 9 and a clarification device 10 connected in sequence. The clarification device 10 is connected to the sulfonation compound agent solution preparation device 2. In the specific implementation process, the desulfurization wastewater obtained in the desulfurization tower 8 undergoes flocculation and sedimentation through the triple system 9, and then clarification in the clarification device 10. Specifically, to further precipitate and reduce the solid content of the solution, the desulfurization wastewater can be subjected to flocculation, sedimentation, and clarification treatment at least twice, sequentially passing through the triple system 9 and the clarification device 10, to obtain clarified desulfurization wastewater and sludge. The sludge is then filtered by a filter press to form sludge cakes for external transport. Specifically, the triple system 9 can be a conventional triple tank in the art, comprising a neutralization device, a flocculation device, and a sedimentation device.

[0041] In the system described in this invention, in a specific embodiment, the sulfonated compound agent solution preparation device 2 can be a sulfonated compound agent emulsification and mixing device, used to input the desulfurized wastewater clarified liquid obtained from the clarification device 10, and to add the sulfonated compound agent to the desulfurized wastewater clarified liquid to obtain the sulfonated compound agent solution.

[0042] In the system described in this invention, in a specific embodiment, the spray gun 3 is connected to the sulfonated compound agent solution preparation device 2, and the nozzle of the spray gun 3 is located between the denitrification device 4 and the air preheater 5 and is disposed within the flue. During specific operation, the spray gun 3 atomizes the sulfonated compound agent solution from the sulfonated compound agent solution preparation device 2 with compressed air through the nozzle and sprays it into the high-temperature flue, completing the removal of SO3 and NH3 from the flue gas. In the actual reaction process, because the sulfonated compound agent contains aromatic compounds, the atomized droplets of the sulfonated compound agent solution continuously evaporate within the high-temperature flue. During evaporation, the aromatic compounds in the sulfonated compound agent undergo a chlorosulfonation reaction with chloride ions in the desulfurization wastewater and SO3 in the flue gas, ultimately generating organic sulfonyl chloride polymer compounds, thereby achieving the removal of SO3 from the flue gas. The reaction process is as follows:

[0043] Ar-H + SO3 → Ar-SO3H ①

[0044] Ar-SO3H+HCl+O2→Cl-Ar-SO3H ②

[0045] Meanwhile, since the sulfonated composite agent also contains carboxymethyl cellulose, the macromolecular chains of carboxymethyl cellulose have certain interactions, easily forming a three-dimensional structure and exhibiting a certain degree of adhesion in solution. Furthermore, the spray formed by the spray gun covers a large portion of the flue gas cross-section, which is more conducive to capturing NH3 gas molecules in the flue gas. In addition, during the evaporation process of the sulfonated composite agent solution, the solidification of inorganic salts such as calcium sulfate and magnesium sulfate, as well as the drying and solidification process of the organic polymer components in the sulfonated composite agent, can all adsorb NH3, thereby achieving the effective removal of NH3.

[0046] In the system described in this invention, in a specific embodiment, the spray gun 3 can be a dual-fluid atomizing spray gun.

[0047] In the system described in this invention, to prevent ammonia escape caused by fluctuations in boiler load, changes in coal quality, changes in flow field, and insufficient catalysis, an online NH3 content detector 6 is installed between the denitrification device 4 and the spray gun 3, located within the flue. During operation, the spray volume of the spray gun is flexibly adjusted according to the unit load and the upstream flue gas ammonia escape situation. When the online NH3 detector shows a high NH3 concentration, the spray volume of the sulfonated compound agent is appropriately increased; conversely, the spray volume is appropriately decreased, achieving intelligent control.

[0048] In the system described in this invention, in order to effectively control SO3 emissions and ensure that SO3 removal is not affected by changes in coal quality and SCR catalyst, thereby flexibly adjusting the spray volume of the spray gun and realizing intelligent control, in a preferred embodiment, an online SO3 content detector 7 is installed between the spray gun 3 and the air preheater 5 and located in the flue.

[0049] In the system described in this invention, in a specific embodiment, the system further includes a dust collector 11 and a fan 12 sequentially arranged on the flue. The dust collector 11 is connected to the air preheater 5, and the fan 12 is connected to the desulfurization tower 8. In the specific implementation process, the desulfurization wastewater in the sulfonated composite agent solution introduced into the flue evaporates in the high-temperature flue gas, the water turning into water vapor. The contained salt crystals are collected by the dust collector 11 along with the fly ash, thus achieving the treatment and disposal of the desulfurization wastewater.

[0050] According to a first embodiment of the system of the present invention, the system for removing SO3 and NH3 from flue gas includes a denitrification device 4, an air preheater 5, and a desulfurization tower 8 connected sequentially through a flue along the flue gas flow direction, and a desulfurization wastewater treatment unit 1, a sulfonation compound agent solution preparation device 2, and a spray gun 3 connected sequentially to the desulfurization tower 8; the sulfonation compound agent solution preparation device 2 is used to mix a sulfonation compound agent containing aromatic compounds and carboxymethyl cellulose with the clarified desulfurization wastewater from the desulfurization wastewater treatment unit 1 to obtain a sulfonation compound agent solution; the nozzle of the spray gun 3 is located between the denitrification device 4 and the air preheater 5 and is disposed in the flue, and is used to atomize the sulfonation compound agent solution from the sulfonation compound agent solution preparation device 2 with compressed air.

[0051] According to a second embodiment of the system described in this invention, the system for removing SO3 and NH3 from flue gas includes a denitrification device 4, an air preheater 5, and a desulfurization tower 8 connected sequentially through a flue along the flue gas flow direction, and a desulfurization wastewater treatment unit 1, a sulfonation compound agent solution preparation device 2, and a spray gun 3 connected sequentially to the desulfurization tower 8. The sulfonation compound agent solution preparation device 2 is used to mix a sulfonation compound agent containing aromatic compounds and carboxymethyl cellulose with the clarified desulfurization wastewater from the desulfurization wastewater treatment unit 1 to obtain a sulfonation compound agent solution. The nozzle of the spray gun 3 is located between the denitrification device 4 and the air preheater 5 and is disposed in the flue, and is used to atomize the sulfonation compound agent solution from the sulfonation compound agent solution preparation device 2 with compressed air. The spray gun 3 is a two-fluid atomizing spray gun.

[0052] According to a third embodiment of the system of the present invention, the system for removing SO3 and NH3 from flue gas includes a denitrification device 4, an air preheater 5, and a desulfurization tower 8 connected sequentially through a flue along the flue gas flow direction, and a desulfurization wastewater treatment unit 1, a sulfonation compound agent solution preparation device 2, and a spray gun 3 connected sequentially to the desulfurization tower 8. The sulfonation compound agent solution preparation device 2 is used to mix a sulfonation compound agent containing aromatic compounds and carboxymethyl cellulose with the clarified desulfurization wastewater from the desulfurization wastewater treatment unit 1 to obtain a sulfonation compound agent solution. The nozzle of the spray gun 3 is located between the denitrification device 4 and the air preheater 5 and is disposed in the flue, and is used to atomize the sulfonation compound agent solution from the sulfonation compound agent solution preparation device 2 with compressed air. The spray gun 3 is a two-fluid atomizing spray gun. The system includes an online NH3 content detector 6 located between the denitrification device 4 and the spray gun 3, and the system also includes an online SO3 content detector 7 located between the spray gun 3 and the air preheater 5.

[0053] According to a fourth embodiment of the system described in this invention, the system for removing SO3 and NH3 from flue gas includes a denitrification device 4, an air preheater 5, and a desulfurization tower 8 connected sequentially through a flue along the flue gas flow direction, and a desulfurization wastewater treatment unit 1, a sulfonation compound agent solution preparation device 2, and a spray gun 3 connected sequentially to the desulfurization tower 8; the sulfonation compound agent solution preparation device 2 is used to mix a sulfonation compound agent containing aromatic compounds and carboxymethyl cellulose with the clarified desulfurization wastewater from the desulfurization wastewater treatment unit 1 to obtain a sulfonation compound agent solution; the nozzle of the spray gun 3 is located at the denitrification device... The device 4 is located between the air preheater 5 and within the flue, and is used to atomize the sulfonated compound agent solution from the sulfonated compound agent solution preparation device 2 with compressed air; the spray gun 3 is a dual-fluid atomizing spray gun; the system includes an online NH3 content detector 6 located between the denitrification device 4 and the spray gun 3, and the system also includes an online SO3 content detector 7 located between the spray gun 3 and the air preheater 5; the desulfurization wastewater treatment unit 1 includes a triple system 9 and a clarification device 10 connected in sequence, and the clarification device 10 is connected to the sulfonated compound agent solution preparation device 2.

[0054] According to a fifth embodiment of the system described in this invention, the system for removing SO3 and NH3 from flue gas includes a denitrification device 4, an air preheater 5, and a desulfurization tower 8 connected sequentially through a flue along the flue gas flow direction, and a desulfurization wastewater treatment unit 1, a sulfonation compound solution preparation device 2, and a spray gun 3 connected sequentially to the desulfurization tower 8. The sulfonation compound solution preparation device 2 is used to mix a sulfonation compound containing aromatic compounds and carboxymethyl cellulose with the clarified desulfurization wastewater from the desulfurization wastewater treatment unit 1 to obtain a sulfonation compound solution. The nozzle of the spray gun 3 is located between the denitrification device 4 and the air preheater 5 and is disposed within the flue, for mixing the sulfonation compound solution from the air preheater 5 with the clarified desulfurization wastewater from the air preheater 5. The sulfonated compound agent solution in the compound agent solution preparation device 2 is atomized with compressed air; the spray gun 3 is a two-fluid atomizing spray gun; the system includes an online NH3 content detector 6 located between the denitrification device 4 and the spray gun 3, and the system also includes an online SO3 content detector 7 located between the spray gun 3 and the air preheater 5; the desulfurization wastewater treatment unit 1 includes a triple system 9 and a clarification device 10 connected in sequence, the clarification device 10 being connected to the sulfonated compound agent solution preparation device 2; the system also includes a dust collector 11 and a fan 12 sequentially installed on the flue, the dust collector 11 being connected to the air preheater 5, and the fan 12 being connected to the desulfurization tower 8.

[0055] A second aspect of this invention provides a method for removing SO3 and NH3 from flue gas, the method comprising the following steps:

[0056] S1. The clarified desulfurization wastewater from the desulfurization wastewater treatment unit is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device to obtain the sulfonation compound agent solution.

[0057] S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun, and then the atomized product is introduced into the flue to treat the flue gas.

[0058] The sulfonated compound contains aromatic compounds and carboxymethyl cellulose.

[0059] In the method described in this invention, in a specific embodiment, the weight ratio of the aromatic compound to the carboxymethyl cellulose is 1-2:1, for example, it can be 1:1, 1.5:1 or 2:1.

[0060] In the method described in this invention, in specific embodiments, the aromatic compound is an alkylphenyl polyoxyethylene ether and / or an alkylbenzene sulfonate. In a preferred embodiment, the aromatic compound is selected from one or more of polyethylene glycol octylphenyl ether, sodium dodecylbenzene sulfonate, and sodium hexadecylbenzene sulfonate.

[0061] In the method described in this invention, in specific embodiments, the carboxymethyl cellulose can be a conventional choice in the art. In a preferred embodiment, the carboxymethyl cellulose is sodium carboxymethyl cellulose.

[0062] In the method described in this invention, in a specific embodiment, the preparation method of the sulfonated compound includes: emulsifying, mixing and stirring an aromatic compound and carboxymethyl cellulose in a certain amount.

[0063] In the method described in this invention, in a specific embodiment, the solid-liquid ratio of the sulfonation compound agent to the clarified desulfurization wastewater is 1g:1000-2000mL, for example, it can be 1g:1000mL, 1g:1500mL or 1g:2000mL.

[0064] In the method described in this invention, in a specific embodiment, the pressure of the compressed air is 0.3-0.4 MPa, and the flow rate is 5-10 m³ / s. 3 / min.

[0065] In the method described in this invention, in a specific embodiment, the particle size of the atomized product is 50-60 μm.

[0066] In the method described in this invention, in a specific embodiment, in step S2, the spray volume of the atomized product is 2-3.5m. 3 / h, for example, can be 2m 3 / h, 2.5m 3 / h、3m3 / h or 3.5m 3 / h.

[0067] In the method described in this invention, in a specific embodiment, the flow rate of the flue gas is 800,000-1,200,000 m³ / h. 3 / h, for example, can be 800000m 3 / h、900000m 3 / h、1000000m 3 / h、1100000m 3 / h or 1200000m 3 / h.

[0068] In the method described in this invention, in a specific embodiment, the flue gas contains 40.29-178.57 mg / m³. 3 SO3, 1.3-3 mg / m³ 3 The NH3. In a preferred embodiment, the temperature of the flue gas is 300-400°C, for example, 300°C, 320°C, 340°C, 360°C, 380°C or 400°C.

[0069] According to a first embodiment of the method described in this invention, the method for removing SO3 and NH3 from flue gas includes the following steps:

[0070] S1. The clarified desulfurization wastewater from the desulfurization wastewater treatment unit is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device to obtain the sulfonation compound agent solution.

[0071] S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun, and then the atomized product is introduced into the flue to treat the flue gas.

[0072] The sulfonated compound contains aromatic compounds and carboxymethyl cellulose.

[0073] According to a second embodiment of the method described in this invention, the method for removing SO3 and NH3 from flue gas includes the following steps:

[0074] S1. The clarified desulfurization wastewater from the desulfurization wastewater treatment unit is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device to obtain the sulfonation compound agent solution.

[0075] S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun, and then the atomized product is introduced into the flue to treat the flue gas.

[0076] The sulfonated compound contains an aromatic compound and carboxymethyl cellulose; the weight ratio of the aromatic compound to the carboxymethyl cellulose is 1-2:1.

[0077] According to a third embodiment of the method described in this invention, the method for removing SO3 and NH3 from flue gas includes the following steps:

[0078] S1. The clarified desulfurization wastewater from the desulfurization wastewater treatment unit is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device to obtain the sulfonation compound agent solution.

[0079] S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun, and then the atomized product is introduced into the flue to treat the flue gas.

[0080] The sulfonated compound contains an aromatic compound and carboxymethyl cellulose; the weight ratio of the aromatic compound to the carboxymethyl cellulose is 1-2:1; the aromatic compound is an alkylphenyl polyoxyethylene ether and / or an alkylbenzene sulfonate, and the aromatic compound is selected from one or more of polyethylene glycol octylphenyl ether, sodium dodecylbenzene sulfonate and sodium hexadecylbenzene sulfonate.

[0081] According to a fourth embodiment of the method described in this invention, the method for removing SO3 and NH3 from flue gas includes the following steps:

[0082] S1. The clarified desulfurization wastewater from the desulfurization wastewater treatment unit is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device to obtain the sulfonation compound agent solution.

[0083] S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun, and then the atomized product is introduced into the flue to treat the flue gas.

[0084] The sulfonated composite agent contains an aromatic compound and carboxymethyl cellulose; the weight ratio of the aromatic compound to the carboxymethyl cellulose is 1-2:1; the aromatic compound is an alkylphenyl polyoxyethylene ether and / or an alkylbenzene sulfonate, and the aromatic compound is selected from one or more of polyethylene glycol octylphenyl ether, sodium dodecylbenzene sulfonate, and sodium hexadecylbenzene sulfonate; the solid-liquid ratio of the sulfonated composite agent to the clarified desulfurization wastewater is 1g:1000-2000mL.

[0085] According to a fifth embodiment of the method described in this invention, the method for removing SO3 and NH3 from flue gas includes the following steps:

[0086] S1. The clarified desulfurization wastewater from the desulfurization wastewater treatment unit is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device to obtain the sulfonation compound agent solution.

[0087] S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun, and then the atomized product is introduced into the flue to treat the flue gas.

[0088] The sulfonated composite agent contains an aromatic compound and carboxymethyl cellulose; the weight ratio of the aromatic compound to the carboxymethyl cellulose is 1-2:1; the aromatic compound is an alkylphenyl polyoxyethylene ether and / or an alkylbenzene sulfonate, and the aromatic compound is selected from one or more of polyethylene glycol octylphenyl ether, sodium dodecylbenzene sulfonate, and sodium hexadecylbenzene sulfonate; the solid-liquid ratio of the sulfonated composite agent to the clarified desulfurization wastewater is 1g:1000-2000mL; the particle size of the atomized product is 50-60μm.

[0089] According to a sixth embodiment of the method described in this invention, the method for removing SO3 and NH3 from flue gas includes the following steps:

[0090] S1. The clarified desulfurization wastewater from the desulfurization wastewater treatment unit is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device to obtain the sulfonation compound agent solution.

[0091] S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun, and then the atomized product is introduced into the flue to treat the flue gas.

[0092] The sulfonated composite agent contains an aromatic compound and carboxymethyl cellulose; the weight ratio of the aromatic compound to the carboxymethyl cellulose is 1-2:1; the aromatic compound is alkylphenyl polyoxyethylene ether and / or alkylbenzene sulfonate, and the aromatic compound is selected from one or more of polyethylene glycol octylphenyl ether, sodium dodecylbenzene sulfonate, and sodium hexadecylbenzene sulfonate; the solid-liquid ratio of the sulfonated composite agent to the clarified desulfurization wastewater is 1g:1000-2000mL; the particle size of the atomized product is 50-60μm; in step S2, the spray volume of the atomized product is 2-3.5m. 3 / h, the flow rate of the flue gas is 800,000-1,200,000 m³ / h. 3 / h.

[0093] According to a seventh embodiment of the method of the present invention, the method for removing SO3 and NH3 from flue gas includes the following steps:

[0094] S1. The clarified desulfurization wastewater from the desulfurization wastewater treatment unit is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device to obtain the sulfonation compound agent solution.

[0095] S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun, and then the atomized product is introduced into the flue to treat the flue gas.

[0096] The sulfonated composite agent contains an aromatic compound and carboxymethyl cellulose; the weight ratio of the aromatic compound to the carboxymethyl cellulose is 1-2:1; the aromatic compound is alkylphenyl polyoxyethylene ether and / or alkylbenzene sulfonate, and the aromatic compound is selected from one or more of polyethylene glycol octylphenyl ether, sodium dodecylbenzene sulfonate, and sodium hexadecylbenzene sulfonate; the solid-liquid ratio of the sulfonated composite agent to the clarified desulfurization wastewater is 1g:1000-2000mL; the particle size of the atomized product is 50-60μm; in step S2, the spray volume of the atomized product is 2-3.5m. 3 / h, the flow rate of the flue gas is 800,000-1,200,000 m³ / h. 3 / h; the flue gas contains 40.29-178.57 mg / m³ 3 SO3, 1.3-3 mg / m³ 3 The NH3 in the flue gas has a temperature of 300-400℃.

[0097] According to an eighth embodiment of the method of the present invention, the method for removing SO3 and NH3 from flue gas includes the following steps:

[0098] S1. The clarified desulfurization wastewater from the desulfurization wastewater treatment unit is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device to obtain the sulfonation compound agent solution.

[0099] S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun, and then the atomized product is introduced into the flue to treat the flue gas.

[0100] The sulfonated composite agent contains an aromatic compound and carboxymethyl cellulose; the weight ratio of the aromatic compound to the carboxymethyl cellulose is 1-2:1; the aromatic compound is alkylphenyl polyoxyethylene ether and / or alkylbenzene sulfonate, and the aromatic compound is selected from one or more of polyethylene glycol octylphenyl ether, sodium dodecylbenzene sulfonate, and sodium hexadecylbenzene sulfonate; the solid-liquid ratio of the sulfonated composite agent to the clarified desulfurization wastewater is 1g:1000-2000mL; the particle size of the atomized product is 50-60μm; in step S2, the spray volume of the atomized product is 2-3.5m. 3 / h, the flow rate of the flue gas is 800,000-1,200,000 m³ / h. 3 / h; the flue gas contains 40.29-178.57 mg / m³ 3 SO3, 1.3-3 mg / m³ 3 The flue gas contains NH3 and has a temperature of 300-400℃; the compressed air has a pressure of 0.3-0.4MPa and a flow rate of 5-10m³ / h.3 / min.

[0101] The following examples further illustrate the system and method for removing SO3 and NH3 from flue gas according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0102] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0103] Test case

[0104] SO3 concentration: chemical absorption method;

[0105] NH3 concentration: absorption spectroscopy;

[0106] Air preheater differential pressure: differential pressure method.

[0107] Example 1

[0108] like Figure 1 As shown, the system for removing SO3 and NH3 from flue gas includes a denitrification device 4, an air preheater 5, a dust collector 11, a fan 12, and a desulfurization tower 8 connected sequentially through a flue along the flue gas flow direction, and a desulfurization wastewater treatment unit 1, a sulfonation compound agent solution preparation device 2, and a spray gun 3 connected sequentially to the desulfurization tower 8; the desulfurization tower 8 is connected to a chimney; the desulfurization wastewater treatment unit 1 includes a triple system 9 and a clarification device 10 connected sequentially, the triple system 9 including a neutralization device, a flocculation device, and a sedimentation device, and the clarification device 10 is connected to the sulfonation compound agent solution preparation device 2 and a filter press respectively; the sulfonation compound agent solution preparation device 2 is used for... A sulfonated composite agent containing aromatic compounds and carboxymethyl cellulose is mixed with clarified desulfurized wastewater from the desulfurization wastewater treatment unit 1 to obtain a sulfonated composite agent solution. The spray gun 3 is a dual-fluid atomizing spray gun, and the nozzle of the spray gun 3 is located between the denitrification device 4 and the air preheater 5 and is set in the flue. It is used to atomize the sulfonated composite agent solution from the sulfonated composite agent solution preparation device 2 with compressed air and then introduce it into the flue. The system also includes an online NH3 content detector 6 located between the denitrification device 4 and the spray gun 3 and an online SO3 content detector 7 located between the spray gun 3 and the air preheater 5.

[0109] The removal of SO3 and NH3 from flue gas using the system includes the following steps:

[0110] S1. During the operation of a 330MW coal-fired unit in a power plant, the desulfurization wastewater generated by the desulfurization tower 8 is sequentially fed into the triple system 9 and the clarification device 10 for flocculation, sedimentation, and clarification. Then, the clarified liquid is sequentially fed into the triple system 9 and the clarification device 10 for a second flocculation, sedimentation, and clarification to obtain a clarified desulfurization wastewater solution. 5000L of the clarified desulfurization wastewater solution is fed into the sulfonation composite agent solution preparation device 2, and 5000g of sulfonation composite agent (the solid-liquid ratio of the sulfonation composite agent to the clarified desulfurization wastewater solution is 1g:1000mL) is added to the clarified desulfurization wastewater solution to obtain a sulfonation composite agent solution. The sulfonation composite agent contains 2500g of polyethylene glycol octylphenyl ether (aromatic compound) and 2500g of sodium carboxymethyl cellulose.

[0111] S2. The sulfonated composite agent solution with a flow rate of 2 t / h is delivered to the two-fluid atomizing spray gun via a spray pump, and atomized together with compressed air at a pressure of 0.4 MPa and a total flow rate of 1.06 t / h through the two-fluid atomizing spray gun, and then the particle size is 50-60 μm, and the spray volume is 2 m. 3 The atomized products are introduced into the flue at a temperature of 340℃ and a flow rate of 1,000,000 m³ / h. 3 The flue gas is in full contact with the air at a concentration of 43.19 mg / m³. 3 SO3, 2.77 mg / m³ 3 The NH3 in the flue gas was treated, and the SO3 concentration was measured to be 26.62 mg / m³. 3 The concentration of NH3 was 0.74 mg / m³. 3 The calculated removal efficiency of SO3 was 38.37%, and that of NH3 was 73.3%. Before the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference of the air preheater increased from 830 Pa to 1422.5 Pa over a three-month period. After the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference increased from 784.6 Pa to 1103.4 Pa over a three-month period. The air preheater pressure difference remained stable, and the blockage and corrosion of the air preheater were significantly reduced compared to the period before it was put into operation.

[0112] Example 2

[0113] The procedure was carried out as described in Implementation 1, except that the solid-liquid ratio of the sulfonated composite agent to the clarified desulfurization wastewater was 1 g: 2000 mL. After treatment, the concentration of SO3 in the flue gas was measured to be 30.22 mg / m³. 3 The concentration of NH3 was 2.05 mg / m³. 3The calculated removal efficiency of SO3 was 30.03%, and the removal efficiency of NH3 was 27.80%. Before the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference of the air preheater increased from 830 Pa to 1520 Pa over a three-month period. After the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference increased from 830 Pa to 1470 Pa over a three-month period. The air preheater pressure difference remained stable, and the blockage and corrosion of the air preheater were significantly reduced compared to the period before it was put into operation.

[0114] Example 3

[0115] The process was carried out according to Embodiment 1, except that the sulfonation compound contained 2000g of sodium dodecylbenzenesulfonate (an aromatic compound) and 1000g of sodium carboxymethyl cellulose (the weight ratio of the aromatic compound to the carboxymethyl cellulose was 2:1). After treatment, the concentration of SO3 in the flue gas was measured to be 29.35 mg / m³. 3 The concentration of NH3 was 1.88 mg / m³. 3 The calculated removal efficiency of SO3 was 32.04%, and that of NH3 was 32.13%. Before the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference of the air preheater increased from 850 Pa to 1560 Pa over a three-month period. After the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference increased from 850 Pa to 1455 Pa over a three-month period. The air preheater pressure difference remained stable, and the blockage and corrosion of the air preheater were significantly reduced compared to the period before the solution was sprayed into operation.

[0116] Comparative Example 1

[0117] The procedure was carried out as described in Implementation 1, except that the aromatic compounds in the sulfonation compound were replaced with calcium oxide. After treatment, the concentration of SO3 in the flue gas was measured to be 35.71 mg / m³. 3 The concentration of NH3 was 2.36 mg / m³. 3 The calculated removal efficiency of SO3 was 17.32%, and that of NH3 was 14.80%. Before the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference of the air preheater increased from 850 Pa to 1450 Pa over a three-month period. After the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference increased from 850 Pa to 1620 Pa over a three-month period. The air preheater pressure difference was unstable, and the blockage and corrosion of the air preheater did not change significantly compared to the period before it was put into operation.

[0118] Comparative Example 2

[0119] The procedure was carried out as described in Implementation 1, except that sodium carboxymethyl cellulose in the sulfonation compound was replaced with sodium hydroxide. After treatment, the concentration of SO3 in the flue gas was measured to be 33.81 mg / m³. 3 The concentration of NH3 was 2.45 mg / m³. 3 The calculated removal efficiency of SO3 was 21.72%, and that of NH3 was 11.55%. Before the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference of the air preheater increased from 850 Pa to 1435 Pa over a three-month period. After the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference increased from 850 Pa to 1525 Pa over a three-month period. The air preheater pressure difference was unstable, and the blockage and corrosion of the air preheater did not change significantly compared to the period before it was put into operation.

[0120] Comparative Example 3

[0121] The procedure was carried out as described in Implementation 1, except that the spray gun 3 was replaced with a single-phase flow spray gun. After treatment, the concentration of SO3 in the flue gas was measured to be 37.22 mg / m³. 3 The concentration of NH3 was 2.56 mg / m³. 3 The calculated removal efficiency of SO3 was 13.82%, and that of NH3 was 7.58%. Before the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference of the air preheater increased from 850 Pa to 1495 Pa over a three-month period. After the sulfonated compound agent solution was sprayed into the air preheater, the monthly average pressure difference increased from 850 Pa to 1610 Pa over a three-month period. The air preheater pressure difference was unstable, and the blockage and corrosion of the air preheater did not change significantly compared to the period before it was put into operation.

[0122] The system described in this invention removes SO3 and NH3 from flue gas, achieving a SO3 removal efficiency of over 30% and an NH3 removal efficiency of over 10%. This method is unaffected by the denitrification system, produces no secondary pollution, and can simultaneously treat desulfurization wastewater.

[0123] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for removing SO3 and NH3 from flue gas, characterized in that, This method is implemented in a system for removing SO3 and NH3 from flue gas, and includes the following steps: S1. The clarified desulfurized wastewater from the desulfurization wastewater treatment unit (1) is mixed with the sulfonation compound agent in the sulfonation compound agent solution preparation device (2) to obtain the sulfonation compound agent solution; S2. The sulfonated composite agent solution and compressed air are atomized through a spray gun (3), and then the atomized product is introduced into the flue to treat the flue gas. The sulfonated compound contains aromatic compounds and carboxymethyl cellulose; The system includes a denitrification device (4), an air preheater (5) and a desulfurization tower (8) connected sequentially through a flue along the flue gas flow direction, and a desulfurization wastewater treatment unit (1), a sulfonation compound agent solution preparation device (2) and a spray gun (3) connected sequentially to the desulfurization tower (8). The sulfonated compound solution preparation device (2) is used to mix the sulfonated compound containing aromatic compounds and carboxymethyl cellulose with the clarified desulfurized wastewater from the desulfurized wastewater treatment unit (1) to obtain the sulfonated compound solution; The nozzle of the spray gun (3) is located between the denitrification device (4) and the air preheater (5) and is disposed in the flue, for atomizing the sulfonated compound agent solution from the sulfonated compound agent solution preparation device (2) with compressed air; The spray gun (3) is a dual-fluid atomizing spray gun; The weight ratio of the aromatic compound to the carboxymethyl cellulose is 1-2:

1.

2. The method according to claim 1, characterized in that, The aromatic compound is an alkylphenyl polyoxyethylene ether and / or an alkylbenzene sulfonate.

3. The method according to claim 2, characterized in that, The aromatic compound is selected from one or more of polyethylene glycol octylphenyl ether, sodium dodecylbenzenesulfonate, and sodium hexadecylbenzenesulfonate.

4. The method according to any one of claims 1-3, characterized in that, The solid-liquid ratio of the sulfonated composite agent to the clarified desulfurization wastewater is 1g:1000-2000mL.

5. The method according to claim 1, characterized in that, The particle size of the atomized product is 50-60 μm.

6. The method according to any one of claims 1-3 and 5, characterized in that, In step S2, the spray volume of the atomized product is 2-3.5m. 3 / h.

7. The method according to claim 6, characterized in that, The flow rate of the flue gas is 800,000-1,200,000 m³ / h. 3 / h.

8. The method according to any one of claims 1-3, 5 and 7, characterized in that, The flue gas contained 40.29-178.57 mg / m³ 3 SO3, 1.3-3 mg / m³ 3 NH3.

9. The method according to claim 8, characterized in that, The temperature of the flue gas is 300-400℃.

10. The method according to any one of claims 1-3, 5, 7 and 8, characterized in that, The pressure of the compressed air is 0.3-0.4 MPa, and the flow rate is 5-10 m³ / min.

11. The method according to any one of claims 1-3, 5, 7 and 8, characterized in that, The system also includes an online NH3 content detector (6) located between the denitrification device (4) and the spray gun (3) for detecting the NH3 content in the flue gas.

12. The method according to claim 11, characterized in that, The system also includes an online SO3 content detector (7) located between the spray gun (3) and the air preheater (5) for detecting the SO3 content in the flue gas.

13. The method according to claim 12, characterized in that, The desulfurization wastewater treatment unit (1) includes a triple system (9) and a clarification device (10) connected in sequence. The clarification device (10) is connected to the sulfonation compound agent solution preparation device (2).

14. The method according to claim 12 or 13, characterized in that, The system also includes a dust collector (11) and a fan (12) arranged sequentially on the flue. The dust collector (11) is connected to the air preheater (5), and the fan (12) is connected to the desulfurization tower (8).

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