Pollutant removal system based on ultrafine grinding modified fly ash

Abstract

The application discloses a kind of pollutant removal systems based on superfine grinding modified fly ash, pollutant removal system includes: boiler, gas-solid separator and drum ball mill, boiler has hearth for combustion and tail flue with hearth communication, the inner wall of drum ball mill is equipped with annular baffle, annular baffle forms modification cavity near the side of fly ash import, gas-solid separator is communicated with fly ash import to import fly ash into modification cavity, annular baffle is used to block the fly ash particles of particle size D50 greater than 20 microns, and allow the fly ash of particle size D50 less than or equal to 20 microns to flow to fly ash export through the center opening of annular baffle, modifier is mixed with fly ash retained in modification cavity and is ground to form fly ash-based adsorbent of particle size D50 less than or equal to 15 microns, fly ash-based adsorbent is discharged from fly ash-based adsorbent export and is transported to the top of hearth and is sprayed, for adsorbing and removing pollutants, to realize the efficient removal of special pollutants such as heavy metals at low cost.

Description

Technical Field

[0001] This invention relates to the field of pollutant removal technology, and in particular to a pollutant removal system based on ultrafine grinding modified fly ash. Background Technology

[0002] Boiler combustion produces special pollutants such as heavy metals and sulfur trioxide. The pollutant control systems in related technologies are unable to effectively remove these special pollutants generated during boiler combustion, resulting in the flue gas produced by boiler combustion failing to meet emission standards. Summary of the Invention

[0003] This invention is based on the inventor's discoveries and understanding of the following facts and problems:

[0004] The inventors discovered that fly ash formed during boiler combustion is a natural adsorbent for special pollutants such as heavy metals and sulfur trioxide. However, untreated fly ash has limited adsorption capacity and cannot effectively remove special pollutants from flue gas.

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a pollutant removal system based on ultrafine grinding modified fly ash, achieving efficient removal of special pollutants such as heavy metals at low cost.

[0006] An embodiment of the present invention discloses a pollutant removal system based on ultrafine mill modified fly ash, comprising: a boiler having a furnace for combustion and a tail flue communicating with the furnace; a gas-solid separator, the tail flue communicating with the gas-solid separator to introduce flue gas into the gas-solid separator, the gas-solid separator being used to separate fly ash from the flue gas; and a drum ball mill having an annular baffle on its inner wall, the drum ball mill having a fly ash inlet and a fly ash outlet, the annular baffle being located between the fly ash inlet and the fly ash outlet, the fly ash inlet and the central opening of the annular baffle being opposite each other axially in the annular baffle, the side of the annular baffle near the fly ash inlet forming a modification cavity, and the gas-solid separator being connected to the furnace. The fly ash inlet is connected to allow fly ash to be introduced into the modification chamber. The annular baffle is used to block fly ash particles with a particle size larger than a first preset particle size and to allow fly ash particles with a particle size smaller than or equal to the first preset particle size to flow to the fly ash outlet through the central opening of the annular baffle. The drum ball mill also has a modifier inlet and a fly ash-based adsorbent outlet connected to the modification chamber. The modifier inlet is used to introduce a modifier. The modifier mixes with the fly ash retained in the modification chamber and is ground to form a fly ash-based adsorbent with a particle size smaller than or equal to a second preset particle size. The fly ash-based adsorbent is discharged from the fly ash-based adsorbent outlet and transported to the top of the furnace for injection to adsorb and remove pollutants, wherein the second preset particle size is smaller than the first preset particle size.

[0007] The pollutant removal system based on ultrafine ground modified fly ash provided in this invention utilizes fly ash generated during boiler combustion as a base to prepare adsorbents, achieving efficient removal of special pollutants such as heavy metals at low cost and reducing the emission concentration of special pollutants in flue gas. Furthermore, an annular baffle separates fly ash with higher carbon content from finer ash with lower carbon content. The fly ash with higher carbon content is modified by a modifier and then injected into the furnace, effectively reducing the carbon content of the fly ash and improving boiler efficiency. The finer ash particles can be sold as a product, offering certain economic benefits.

[0008] In some embodiments, the annular baffle is used to block fly ash particles with a particle size D50 greater than 20 micrometers and allow fly ash particles with a particle size D50 less than or equal to 20 micrometers to flow through the central opening of the annular baffle to the fly ash outlet; and / or, the modifier is mixed with the fly ash retained in the modification cavity and ground to form a fly ash-based adsorbent with a particle size D50 less than or equal to 15 micrometers.

[0009] In some embodiments, the pollutant removal system includes an air inlet duct connected to the fly ash inlet, a gas-solid separator connected to the air inlet duct, and the air inlet duct is used to introduce pressurized air to carry the fly ash into the drum ball mill.

[0010] In some embodiments, a dispersion plate is provided inside the modification cavity, and a plurality of dispersion holes are provided on the dispersion plate. The dispersion plate and the cavity wall surface of the modification cavity are spaced apart to form an interlayer. The modifier inlet is connected to the interlayer. The dispersion plate is used to disperse the modifier into the modification cavity.

[0011] In some embodiments, the system further includes a duckbill-shaped guide plate and an adjustment mechanism. The duckbill-shaped guide plate is disposed at the fly ash inlet to guide the fly ash and control the fly ash dispersion angle. The adjustment mechanism is connected to the duckbill-shaped guide plate to adjust the angle of the duckbill-shaped guide plate, thereby adjusting the fly ash dispersion angle.

[0012] In some embodiments, a first screen and a second screen are further provided in the cavity on the side of the annular baffle near the fly ash outlet. The first screen and the second screen divide the cavity into a first chamber, a second chamber and a third chamber. The first chamber, the second chamber and the third chamber are distributed sequentially in the fly ash flow direction and the fly ash outlet is connected to the third chamber. The first chamber and the second chamber each have grinding balls for grinding. The first screen is used to block fly ash particles of larger diameter and allow fly ash particles of smaller diameter to pass through and enter the second chamber. The second screen is used to block fly ash particles of larger diameter and allow fly ash particles of smaller diameter to pass through and enter the third chamber.

[0013] In some embodiments, the system further includes a grinding aid and a mineral powder silo, which is connected to the first chamber for introducing the grinding aid and mineral powder into the first chamber. The grinding aid and mineral powder are mixed with fly ash retained in the first chamber and ground until they pass through the first screen.

[0014] In some embodiments, the annular baffle includes a first end plate, a baffle, and a second end plate arranged sequentially at intervals along its axial direction. The first end plate and the second end plate are porous plates, and the baffle is a blind plate. The first end plate is located on the side close to the fly ash inlet. The fly ash-based adsorbent outlet is located at the bottom of the drum ball mill and communicates with the gap between the first end plate and the baffle. The through holes on the first end plate allow fly ash-based adsorbent with a particle size less than or equal to a second preset particle size to pass through. And / or, the grinding aid and mineral powder bin communicate with the first chamber through the gap between the baffle and the second end plate.

[0015] In some embodiments, the fly ash outlet includes a first fly ash outlet and a second fly ash outlet, the first fly ash outlet being connected to the bottom of the third chamber, the second fly ash outlet being located above the first fly ash outlet, and the fly ash particles discharged from the second fly ash outlet having a smaller particle size than the fly ash particles discharged from the first fly ash outlet.

[0016] In some embodiments, an electrostatic separation device is also included, which is connected to the second fly ash outlet and is used to electrostatically separate ultrafine ash with a particle size D50 of less than or equal to 2 micrometers.

[0017] In some embodiments, the first screen allows fly ash with a particle size D50 of less than or equal to 15 micrometers to pass through; and / or, the second screen allows fly ash with a particle size D50 of less than or equal to 10 micrometers to pass through. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the pollutant removal system based on ultrafine grinding modified fly ash provided in an embodiment of the present invention.

[0019] Figure 2 yes Figure 1 AA section view.

[0020] Figure label: Boiler 1, Furnace 11, Tail flue 12, Chimney 13 Gas-solid separator 2, fly ash conveying inlet pipe 21, 3. Rotary ball mill; 31. Fly ash inlet; 311. Duckbill-shaped guide plate; 312. Adjustment mechanism; 32. Fly ash outlet; 321. First fly ash outlet; 322. Second fly ash outlet; 33. Annular baffle; 331. First end plate; 332. Baffle; 333. Second end plate; 34. Steel ball; 35. Fly ash-based adsorbent outlet; 351. Fly ash-based adsorbent discharge and conveying pipeline; 36. Dispersion plate; 361. Dispersion hole; 37. First screen; 38. Second screen. Modified cavity 301, first chamber 302, second chamber 303, third chamber 304 4. Air inlet pipe, 5. Grinding aid and mineral powder silo, 6. Electrostatic separation equipment, 7. Dust collector, 7. Air outlet, 71. Powder discharge pipe, 72. Modifier storage silo, 8. Material discharge pipe. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0022] The following is based on Figure 1 and Figure 2 This invention describes a pollutant removal system based on ultrafine grinding modified fly ash, provided by an embodiment of the present invention.

[0023] The pollutant removal system includes a boiler 1, a gas-solid separator 2, and a drum ball mill 3. The boiler 1 has a furnace 11 for combustion and a tail flue 12 connected to the furnace 11. The flue gas generated by combustion in the furnace 11 is discharged through the tail flue 12, and the flue gas discharged from the tail flue 12 contains fly ash.

[0024] The tail flue 12 is connected to the gas-solid separator 2 to introduce flue gas into the gas-solid separator 2. The gas-solid separator 2 is used to perform gas-solid separation to separate fly ash from the flue gas.

[0025] The rotary ball mill 3 has a fly ash inlet 31 and a fly ash outlet 32. The solid outlet of the gas-solid separator 2 is connected to the fly ash inlet 31 of the rotary ball mill 3 to introduce fly ash separated from the flue gas into the fly ash inlet 31. The rotary ball mill 3 is used to grind the fly ash particles. The cavity of the rotary ball mill 3 is equipped with several grinding balls for grinding. The grinding balls collide with each other to grind the particles.

[0026] An annular baffle 33 is provided on the inner wall of the drum ball mill 3. The annular baffle 33 is located between the fly ash inlet 31 and the fly ash outlet 32. The outer circumferential surface of the annular baffle 33 is connected to the inner wall of the drum ball mill 3, and the inner circumferential surface of the annular baffle 33 defines a central opening. The fly ash inlet 31 and the central opening of the annular baffle 33 are opposite each other in the axial direction of the annular baffle 33. The side of the annular baffle 33 near the fly ash inlet 31 forms a modification cavity 301. The gas-solid separator 2 is connected to the fly ash inlet 31 of the drum ball mill 3 to introduce fly ash into the modification cavity 301. The annular baffle 33 is used to block fly ash particles with a particle size larger than a first preset particle size, retaining the fly ash particles in the modification cavity 301. At the same time, the annular baffle 33 allows fly ash particles with a particle size smaller than or equal to the first preset particle size to flow to the fly ash outlet 32 ​​through the central opening of the annular baffle 33, thereby separating fly ash with a large particle size D50 from fly ash with a small particle size D50. Generally, the fly ash with large particle size D50 retained in the modification cavity 301 is fly ash with a high carbon content.

[0027] The drum ball mill 3 also has a modifier inlet and a fly ash-based adsorbent outlet 35 connected to the modification chamber 301. The modifier inlet is used to introduce the modifier. After the modifier mixes with the fly ash retained in the modification chamber 301, it is ground and modified under the action of grinding balls (steel balls 34) in the modification chamber 301, exposing the carbon inside the fly ash to the outside, forming a fly ash-based adsorbent. After the fly ash-based adsorbent is ground to a particle size less than or equal to a second preset particle size, it is discharged from the fly ash-based adsorbent outlet 35 and conveyed to the top of the furnace 11 for injection to adsorb and remove pollutants, especially heavy metals, sulfur trioxide and other special pollutants in the flue gas. The modified fly ash-based adsorbent has a greatly enhanced ability and efficiency in removing heavy metals and other special pollutants. In particular, the fly ash-based adsorbent has a finer particle size after grinding and a larger specific surface area, which can better adsorb special pollutants. The second preset particle size is smaller than the first preset particle size.

[0028] The operation process of the pollutant removal system based on ultrafine ground modified fly ash provided in this embodiment of the invention is as follows: Flue gas is generated by combustion in the furnace 11 of boiler 1. The flue gas contains fly ash. The flue gas enters the gas-solid separator 2 through the tail flue 12 to separate the fly ash. The separated fly ash is sent to the drum ball mill 3. First, the fly ash entering the modification chamber 301 will have heavier, larger particles collide with the annular baffle 33 and be retained in the modification chamber 301. Lighter, smaller particles flow downstream from the opening in the middle of the annular baffle 33 and continue to be ground into finer particles. The fly ash retained in the modification chamber 301 mixes with the modifier input into the modification chamber 301. Under the action of the steel balls 34 in the modification chamber 301, a fly ash-based adsorbent is formed. The fly ash-based adsorbent is discharged from the modification chamber 301 and input to the top of the furnace 11.

[0029] The pollutant removal system based on ultrafine ground modified fly ash provided in this invention utilizes fly ash generated during boiler combustion as a base to prepare adsorbents, achieving efficient removal of special pollutants such as heavy metals at low cost and reducing the emission concentration of special pollutants in flue gas. Furthermore, an annular baffle separates fly ash with higher carbon content from finer ash particles. The fly ash with higher carbon content is modified by a modifier and then injected into the furnace, effectively reducing the carbon content of the fly ash and improving boiler efficiency. The finer ash particles can be sold as a fine ash product, offering certain economic benefits.

[0030] Optionally, the modifier is one or a mixture of several of CaO, Al2O3, SiO2, and S.

[0031] In some embodiments, the annular baffle 33 is used to block fly ash particles with a particle size D50 greater than 20 micrometers, retaining the fly ash particles in the modified cavity 301. At the same time, the annular baffle 33 allows fly ash particles with a particle size D50 less than or equal to 20 micrometers to flow through the central opening of the annular baffle 33 to the fly ash outlet 32.

[0032] In some embodiments, the modifier is mixed with fly ash retained in the modification cavity 301 and ground to form a fly ash-based adsorbent with a particle size D50 of less than or equal to 15 micrometers.

[0033] It should be noted that particle size D50 refers to the particle size corresponding to a sample when the cumulative particle size distribution percentage reaches 50%.

[0034] In some embodiments, in order to smoothly feed fly ash into the drum ball mill 3, the pollutant removal system includes an air inlet pipe 4, which is connected to the fly ash inlet 31 of the drum ball mill 3. The gas-solid separator 2 is connected to the air inlet pipe 4. The air inlet pipe 4 is used to introduce pressurized air to carry the fly ash into the drum ball mill 3. That is, under the drive of the air, the fly ash discharged from the gas-solid separator 2 is blown into the drum ball mill 3.

[0035] In some embodiments, a dispersion plate 36 is provided in the modification cavity 301, and a plurality of dispersion holes 361 are provided on the dispersion plate 36. The dispersion plate 361 and the cavity wall surface of the modification cavity 301 are spaced apart to form an interlayer. The modifier inlet is connected to the interlayer. The dispersion plate 361 is used to disperse the modifier into the modification cavity 301, thereby promoting uniform mixing of the modifier and fly ash and making the modification process more complete.

[0036] As an example, the fly ash inlet 31 of the drum ball mill 3 is located on its left side, and the fly ash outlet 32 ​​is located on its right side. A dispersion plate 36 is positioned opposite each other on the left inner wall of the drum ball mill 3. The dispersion plate 36 and the left inner wall of the drum ball mill 3 are spaced apart to form a sandwich layer. The modifier inlet communicates with the sandwich layer. Several dispersion holes 361 are formed on the side of the dispersion plate 36 away from the central axis of the drum ball mill 3. One end of each dispersion hole 361 communicates with the sandwich layer, and the other end communicates with the modification cavity 301. The modifier enters the sandwich layer through the modifier inlet, disperses within the sandwich layer, and is dispersed into the modification cavity 301 through the dispersion holes 361 communicating with the sandwich layer. Figure 1 As shown, the modification cavity 301 is filled with several steel balls 34 for grinding. The modifier is mixed with the fly ash retained in the modification cavity 301. Under the action of the steel balls 34, the carbon inside the fly ash is exposed to the outside, forming a fly ash-based adsorbent. After the fly ash-based adsorbent is ground by the steel balls 34 to a particle size D50 of less than or equal to 15 micrometers, the fly ash-based adsorbent is discharged from the fly ash-based adsorbent outlet 35 and transported to the top of the furnace 11 for injection.

[0037] In some embodiments, such as Figure 1 As shown, the pollutant removal system also includes a duckbill-shaped guide plate 311 and an adjustment mechanism 312. The duckbill-shaped guide plate 311 is located at the fly ash inlet 31 to guide the fly ash and control its dispersion angle. Fly ash entering from the fly ash inlet 31 is guided by the duckbill-shaped guide plate 311 and sprayed into the modification chamber 301 at a certain dispersion angle. A portion of the fly ash with larger particle sizes impacts the annular baffle 33. The ratio of fly ash retained in the modification chamber 301 to fly ash passing through the annular baffle 33 is related to the dispersion angle at which the fly ash is sprayed into the modification chamber 301. The larger the dispersion angle, the more fly ash will impact the annular baffle 33. The adjustment mechanism 312 is connected to the duckbill-shaped guide plate 311 to adjust the angle of the duckbill-shaped guide plate 311, thereby adjusting the dispersion angle of the fly ash and thus adjusting the ratio of fly ash retained in the modification chamber 301 to fly ash passing through the annular baffle 33.

[0038] In some embodiments, a first screen 37 and a second screen 38 are further provided in the cavity of the annular baffle 33 near the fly ash outlet 32. The first screen 37 is located between the annular baffle 33 and the second screen 38 in the fly ash flow direction. The first screen 37 and the second screen 38 divide the cavity into a first chamber 302, a second chamber 303, and a third chamber 304. The modified cavity 301, the first chamber 302, the second chamber 303, and the third chamber 304 are sequentially distributed in the fly ash flow direction, and the fly ash outlet 32 ​​communicates with the third chamber 303. Both the first chamber 302 and the second chamber 303 contain grinding balls (steel balls 34) for grinding. The first screen 37 is used to block larger-diameter fly ash particles and allow smaller-diameter fly ash particles to pass through and enter the second chamber 303, and the second screen 38 is used to block larger-diameter fly ash particles and allow smaller-diameter fly ash particles to pass through and enter the third chamber 304.

[0039] Fly ash passing through the central opening of the annular partition 33 enters the first chamber 302. A portion of the larger fly ash particles entering the first chamber 302 are blocked and retained in the first chamber 302 by the first screen 37, while the smaller fly ash particles pass through the first screen 37 and enter the second chamber 303. The fly ash retained in the first chamber 302 is ground by the steel balls 34 in the first chamber 302 until it is ground to a certain particle size and can pass through the first screen 37. A portion of the larger fly ash particles entering the second chamber 303 are blocked and retained in the second chamber 303 by the second screen 38, while the smaller fly ash particles pass through the second screen 38 and enter the third chamber 304. The fly ash retained in the second chamber 303 is ground by the steel balls 34 in the second chamber 303 until it is ground to a certain particle size and can pass through the second screen 38. The fly ash in the third chamber 304 is discharged from the ball mill 3 through the fly ash outlet 32. The setting of the first screen 37 and the second screen 38 enables the step-by-step screening and grinding of fly ash in the drum ball mill 3, which helps to fully grind the fly ash and discharge it after grinding it to the qualified particle size, thus forming a qualified fine ash product with good economic benefits.

[0040] Optionally, the first screen 37 allows fly ash with a particle size D50 less than or equal to 15 micrometers to pass through, that is, the fly ash entering the second chamber 303 has a particle size D50 less than or equal to 15 micrometers.

[0041] Optionally, the second screen 38 allows fly ash with a particle size D50 less than or equal to 10 micrometers to pass through, that is, fly ash with a particle size D50 less than or equal to 10 micrometers that enters the third chamber 304 and is discharged from the fly ash outlet.

[0042] In some embodiments, in order to promote the grinding of fly ash, the contaminant removal system further includes a grinding aid and mineral powder bin 5, which is connected to the first chamber 302 for introducing grinding aid and mineral powder into the first chamber 302. The grinding aid and mineral powder are mixed with the fly ash retained in the first chamber 302 and ground until the fly ash is ground to a qualified particle size and can pass through the first screen 37. The grinding aid and mineral powder are used to promote the grinding of fly ash.

[0043] In some embodiments, the annular baffle 33 includes a first end plate 331, a baffle 332, and a second end plate 333 sequentially spaced apart in its axial direction. The first end plate 331 and the second end plate 333 are perforated plates, the baffle 332 is a blind plate, and the first end plate 331 is located on the side near the fly ash inlet 31. The gap between the first end plate 331 and the baffle 332 communicates with the modified cavity 301 through an opening on the first end plate 331, and the gap between the second end plate 333 and the baffle 332 communicates with the first chamber 302 through an opening on the second end plate 333. It is understood that the first end plate 331, the baffle 332, and the second end plate 333 are all annular plates. Figure 1 As shown, the inner sides of the first end plate 331, the baffle 332, and the second end plate 333 are closed.

[0044] Furthermore, the fly ash-based adsorbent outlet 35 is located at the bottom of the drum mill 3 and communicates with the gap between the first end plate 331 and the baffle 332. The through-holes on the first end plate 331 allow fly ash-based adsorbent with a particle size less than or equal to the second preset particle size to pass through. In some specific embodiments, the through-holes on the first end plate 331 allow fly ash-based adsorbent with a particle size D50 less than or equal to 15 micrometers to pass through.

[0045] Specifically, the modifier is thoroughly mixed with the coarse-grained fly ash retained in the modification chamber 301, and then ground and modified by the action of the steel balls 34 in the modification chamber 301, exposing the carbon inside the fly ash to the outside, forming a highly efficient fly ash-based adsorbent. After the fly ash-based adsorbent reaches a certain fineness (particle size D50 less than or equal to 15 micrometers), it enters the gap between the first end plate 331 and the baffle 332 through the through holes on the first end plate 331 of the annular partition 33, and is discharged through the fly ash-based adsorbent outlet 35. This arrangement ensures that the fly ash-based adsorbent particle size D50 discharged from the fly ash-based adsorbent outlet 35 after being screened by the first screen 37 is less than or equal to 15 micrometers.

[0046] Furthermore, in order for the annular baffle 33 to better block larger fly ash particles, such as Figure 2As shown, the inner ring portion of the first end plate 331 near the central opening is a blind plate, and the outer ring portion away from the central opening is a perforated plate with several through holes distributed thereon. Fly ash particles with a larger particle size D50 (particle size D50 greater than 20 micrometers) injected into the modification cavity 301 collide with the inner ring portion of the first end plate 331 and are blocked, remaining in the modification cavity 301.

[0047] In some embodiments, the grinding aid and mineral powder bin 5 is connected to the first chamber 302 through a gap between the baffle 332 and the second end plate 333. For example... Figure 1 As shown, the grinding aid and mineral powder bin 5 is located above the drum ball mill 3. The grinding aid and mineral powder bin 5 introduces grinding aid and mineral powder into the gap between the baffle 332 and the second end plate 333. The grinding aid and mineral powder in the gap are dispersed into the first chamber 302 through the through holes on the second end plate 333. This arrangement allows the grinding aid and mineral powder to be more evenly mixed with the fly ash in the first chamber 302 after entering the first chamber 302, which helps to grind the fly ash evenly.

[0048] In some embodiments, such as Figure 1 As shown, the diameter of the steel ball 34 in the second chamber 303 is smaller than that of the steel ball 34 in the first chamber 302. The smaller diameter steel ball 34 is suitable for finer grinding, grinding fly ash to a finer particle size.

[0049] The fly ash that passes through the second screen 38 and enters the third chamber 304 has a certain particle size dispersion. In order to separate the ultrafine fly ash from this part of the fly ash, in some embodiments, such as... Figure 1 As shown, the fly ash outlet 32 ​​of the drum ball mill 3 includes a first fly ash outlet 321 and a second fly ash outlet 322. The first fly ash outlet is connected to the bottom of the third chamber 304, and the second fly ash outlet 322 is located above the first fly ash outlet 321. The fly ash particles discharged from the second fly ash outlet 322 are smaller than the fly ash particles discharged from the first fly ash outlet 321.

[0050] Specifically, such as Figure 1 As shown, the second fly ash outlet 322 is located on the central axis of the drum ball mill 3, opposite to the fly ash inlet 31. The fly ash particles with ultra-fine particle size that pass through the second screen 38 into the third chamber 304 are lighter and are directly discharged through the second fly ash outlet 322 under the carry of air. Most of the remaining fly ash will collide with the inner wall of the third chamber 304 and concentrate at the bottom of the third chamber 304, and be discharged through the first fly ash outlet 321.

[0051] Furthermore, the pollutant removal system also includes an electrostatic separation device 6, which is connected to the second fly ash outlet 322 and is used to electrostatically separate ultrafine ash with a particle size D50 of less than or equal to 2 micrometers. Specifically, fly ash discharged directly through the second fly ash outlet 322 under the carry of air enters the electrostatic separation device 6. The electrostatic separation device 6 has positive and negative electrodes. Under the action of the positive electrode "+" and the negative electrode "-", ultrafine particles (particle size D50 of less than or equal to 2 micrometers) are captured by the positive electrode "+", forming ultrafine ash product. Particles that are not captured enter the dust collector 7 to achieve air / powder separation. The air is discharged through the air outlet 71, while the powder is discharged through the powder discharge pipe 72 and merged with the material discharge pipe 9 as the finished fine ash product. Through separation, the fine ash with low carbon content is ground and further separated into ordinary fine ash product and ultrafine ash product for sale, which can generate good economic benefits.

[0052] The following is based on Figure 1 and Figure 2 Describes a pollutant removal system in a specific embodiment of the present invention.

[0053] like Figure 1 As shown, the fly ash produced by combustion in the furnace 11 of boiler 1 undergoes partial adsorption and removal of specific pollutants in the tail flue 12, and is then collected by a gas-solid separator 2 (e.g., a dust collector). The purified flue gas is discharged through the chimney 13. The fly ash to be treated collected by the gas-solid separator 2 enters the drum mill 3 through the fly ash conveying inlet pipe 21. Simultaneously, pressurized air is connected to the fly ash conveying inlet pipe 21 through the air inlet pipe 4, carrying the fly ash to be treated into the drum mill 3.

[0054] The drum ball mill 3 is divided into four regions: a modification chamber 301, a first chamber 302, a second chamber 303, and a third chamber 304. The modification chamber 301 and the first chamber 302 are separated by an annular partition 33. Figure 2 As shown, the end plate of the annular partition 33 near the modification chamber 301 is the first end plate 331. The outer ring of the first end plate 331 is an annular porous plate, and the inner ring is a blind plate. The end plate of the annular partition 33 near the first chamber 302 is the second end plate 333, which is also a porous plate. After pressurized air carries the fly ash to be treated into the modification chamber 301, the coarse fly ash with higher carbon content (D50 > 20 μm) collides with the annular partition 33 under gravity and remains in the modification chamber 301, while the fine fly ash with lower carbon content (D50 ≤ 20 μm) enters the first chamber 302 with the air through the central opening of the annular partition 33, thus achieving separation.

[0055] Modifier is introduced into the modifier storage silo 8 through the modifier inlet. The modifier then enters the modification chamber 301 through the dispersion holes 361 on the dispersion plate 36, where it is thoroughly mixed with the coarse fly ash particles remaining in the modification chamber 301. Under the action of the steel balls 34 in the modification chamber 301, the modifier is ground and modified, exposing the carbon inside the fly ash to the outside, forming a highly efficient fly ash-based adsorbent. After the fly ash-based adsorbent reaches a certain fineness (D50≤15 μm), it enters the annular baffle 33 through the first end plate 331 and is discharged through the fly ash-based adsorbent outlet 35. It is then sent to the top of the furnace 11 along the fly ash-based adsorbent discharge and conveying pipeline 351, with the inlet close to the tail flue 12, to enhance the adsorption and removal of special pollutants in the flue gas.

[0056] The air-carrying fly ash entering the first chamber 302 further impacts the first screen 37, causing medium to large particle sizes (D50 > 15 μm) of fly ash to remain in the first chamber 302, while small particle sizes (D50 ≤ 15 μm) pass directly through the first screen 37 into the second chamber 303. Simultaneously, the grinding aid and mineral powder bin 5 feeds the grinding aid and mineral powder into the first chamber 302 through the second end plate 333. Together with the fly ash retained in the first chamber 302, they are further ground by the steel balls 34 in the first chamber 302 until a certain fineness (D50 ≤ 15 μm) is achieved, after which they pass through the first screen 37 into the second chamber 303.

[0057] The fly ash entering the second chamber 303 is carried by the air. Some of the qualified fine fly ash particles (D50≤10 μm) pass directly through the second screen 38 into the third chamber 304. The fly ash that does not reach the required fine particle size is further ground by the steel balls 34 in the second chamber 303 until the required fineness (D50≤10 μm) is achieved. After all the fly ash that reaches the required fineness (D50≤10 μm) enters the third chamber 304, most of it is discharged through the discharge pipe 9. A small portion of even finer particles are carried by the air into the electrostatic separator 6. Under the action of the "+" and "-" electrodes, the ultrafine particles are captured by the "+" stage, forming an ultrafine ash product (D50≤2 μm). Particles that fail to be captured enter the dust collector 7 to achieve air / powder separation. The air is discharged through the air outlet 71, while the powder is discharged through the powder discharge pipe 72 and merges with the material discharge pipe 9 to form a fine ash product (D50≤10 μm).

[0058] The pollutant removal system in the specific embodiment of the present invention has the following advantages: (1) Using fly ash as the basis to prepare adsorbents can effectively reduce the emission concentration of special pollutants such as heavy metals at the lowest cost; (2) By sorting and processing fly ash with high carbon content, it is transported to the top of the furnace for injection, which can reduce the carbon content of fly ash and improve boiler efficiency; (3) Through the sorting of this patent, the fine ash with low carbon content is ground and further sorted into ordinary fine ash products and ultrafine ash products for sale, which can generate good economic benefits.

[0059] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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 invention.

[0060] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0061] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0062] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0063] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0064] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A pollutant removal system based on ultrafine milled modified fly ash, characterized in that, include: A boiler having a furnace for combustion and a tail flue communicating with the furnace; A gas-solid separator, wherein the tail flue is connected to the gas-solid separator to introduce flue gas into the gas-solid separator, and the gas-solid separator is used to separate fly ash from the flue gas. A rotary ball mill, wherein an annular baffle is provided on the inner wall surface of the rotary ball mill, the rotary ball mill has a fly ash inlet and a fly ash outlet, the annular baffle is located between the fly ash inlet and the fly ash outlet, the fly ash inlet and the central opening of the annular baffle are opposite each other in the axial direction of the annular baffle, the side of the annular baffle near the fly ash inlet forms a modification cavity, a gas-solid separator is connected to the fly ash inlet to introduce fly ash into the modification cavity, the annular baffle is used to block fly ash particles with a particle size larger than a first preset particle size, and allow particles with a particle size less than or equal to the first preset particle size. Fly ash of a preset particle size flows to the fly ash outlet through the central opening of the annular partition. The drum ball mill also has a modifier inlet and a fly ash-based adsorbent outlet connected to the modification chamber. The modifier inlet is used to introduce a modifier, which mixes with the fly ash retained in the modification chamber and is ground to form a fly ash-based adsorbent with a particle size less than or equal to a second preset particle size. The fly ash-based adsorbent is discharged from the fly ash-based adsorbent outlet and transported to the top of the furnace for injection to adsorb and remove pollutants. The second preset particle size is smaller than the first preset particle size.

2. The pollutant removal system based on ultrafine mill modified fly ash according to claim 1, characterized in that, The annular baffle is used to block fly ash particles with a particle size D50 greater than 20 micrometers, and allows fly ash particles with a particle size D50 less than or equal to 20 micrometers to flow through the central opening of the annular baffle to the fly ash outlet. And / or, the modifier is mixed with fly ash retained in the modification cavity and ground to form a fly ash-based adsorbent with a particle size D50 of less than or equal to 15 micrometers.

3. The pollutant removal system based on ultrafine mill modified fly ash according to claim 1, characterized in that, It includes an air inlet pipe, which is connected to the fly ash inlet, and a gas-solid separator, which is connected to the air inlet pipe. The air inlet pipe is used to introduce pressurized air to carry the fly ash into the drum ball mill.

4. The pollutant removal system based on ultrafine grinding modified fly ash according to claim 1, characterized in that, The modification cavity is provided with a dispersion plate, which has a plurality of dispersion holes. The dispersion plate and the cavity wall of the modification cavity are spaced apart to form an interlayer. The modifier inlet is connected to the interlayer. The dispersion plate is used to disperse the modifier into the modification cavity.

5. The pollutant removal system based on ultrafine grinding modified fly ash according to claim 1, characterized in that, It also includes a duckbill-shaped guide plate and an adjustment mechanism. The duckbill-shaped guide plate is located at the fly ash inlet to guide the fly ash and control the fly ash dispersion angle. The adjustment mechanism is connected to the duckbill-shaped guide plate to adjust the angle of the duckbill-shaped guide plate, thereby adjusting the fly ash dispersion angle.

6. The pollutant removal system based on ultrafine grinding modified fly ash according to claim 1, characterized in that, The annular baffle is further provided with a first screen and a second screen in the cavity on the side near the fly ash outlet. The first screen and the second screen divide the cavity into a first chamber, a second chamber and a third chamber. The first chamber, the second chamber and the third chamber are distributed sequentially in the fly ash flow direction and the fly ash outlet is connected to the third chamber. The first chamber and the second chamber each have grinding balls for grinding. The first screen is used to block fly ash particles of larger diameter and allow fly ash particles of smaller diameter to pass through and enter the second chamber. The second screen is used to block fly ash particles of larger diameter and allow fly ash particles of smaller diameter to pass through and enter the third chamber.

7. The pollutant removal system based on ultrafine mill modified fly ash according to claim 6, characterized in that, It also includes a grinding aid and a mineral powder silo, which is connected to the first chamber for introducing the grinding aid and mineral powder into the first chamber. The grinding aid and mineral powder are mixed with the fly ash retained in the first chamber and ground until they pass through the first screen.

8. The pollutant removal system based on ultrafine grinding modified fly ash according to claim 7, characterized in that, The annular baffle includes a first end plate, a baffle, and a second end plate arranged sequentially at intervals along its axial direction. The first end plate and the second end plate are perforated plates, and the baffle is a blind plate. The first end plate is located on the side close to the fly ash inlet. The fly ash-based adsorbent outlet is located at the bottom of the drum ball mill and is connected to the gap between the first end plate and the baffle. The through holes on the first end plate allow fly ash-based adsorbent with a particle size less than or equal to the second preset particle size to pass through. And / or, the grinding aid and mineral powder bin are connected to the first chamber through the gap between the baffle and the second end plate.

9. The pollutant removal system based on ultrafine mill modified fly ash according to any one of claims 6-8, characterized in that, The fly ash outlet includes a first fly ash outlet and a second fly ash outlet. The first fly ash outlet is connected to the bottom of the third chamber, and the second fly ash outlet is located above the first fly ash outlet. The fly ash particles discharged from the second fly ash outlet are smaller than the fly ash particles discharged from the first fly ash outlet.

10. The pollutant removal system based on ultrafine mill modified fly ash according to claim 9, characterized in that, It also includes an electrostatic separation device, which is connected to the second fly ash outlet and is used to electrostatically separate ultrafine ash with a particle size D50 of less than or equal to 2 micrometers.

Images