Fly ash and sludge synergistic recycling system and method

Abstract

According to the system, fine ash with the highest effective component content is screened and recycled through a screening unit, superfine ash with effective reactants fully exposed is obtained through crushing, grinding and wall breaking of a crushing unit, the superfine ash is screened for the second time through a negative pressure conveying unit, and the superfine ash is recycled through a sludge recycling unit. Then the superfine ash is quantitatively added into the sludge drying unit, mixed and dried with the sludge in proportion and then fed into a furnace to be blended with the garbage for combustion, so that pretreatment of acidic substances in the sludge is achieved, slaked lime in the superfine ash can react with acidic gas in flue gas after the superfine ash is fed into the furnace, and the effect of purifying the flue gas is achieved; the system disclosed by the invention can be used for performing multiple desulfurization and deacidification on the sludge and garbage blending combustion process, so that the slaked lime is in more sufficient contact with acidic substances, and the reaction is more sufficient. According to the system, the pressure of fly ash chelating solidification and product landfill is greatly reduced through effective cyclic utilization, the comprehensive utilization rate of slaked lime is increased, and the steam consumption of sludge and garbage co-treatment can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of fly ash recycling equipment, and specifically relates to a fly ash and sludge coordinated recycling system and method. Background Art

[0002] The flue gas generated during the waste incineration power generation process needs to be treated by flue gas purification before it can meet the emission standards. Semi-dry deacidification is the mainstream method for flue gas purification in waste incineration power plants. Slaked lime is usually used as the reaction material with acidic gases in the flue gas. The slaked lime is prepared into a lime slurry solution and sprayed into the reaction tower through a high-speed rotary atomizer to fully contact and react with the flue gas. The deacidification rate is very high, with a SO2 removal rate of 85% and a HCl removal rate of 99%. However, the utilization rate of slaked lime is only about 35%. The excess slaked lime and other dust after the reaction are collected by the fly ash scraper at the bottom of the reaction tower and the bottom of the bag filter, and transported to the fly ash bin for chelation and solidification by the collection scraper, and then transported to the landfill for centralized treatment. According to the test, the slaked lime content in the fly ash is between 29% and 34%, which has caused huge material waste, and also increased the processing pressure of fly ash solidification in the plant and landfill outside the plant. The sludge from sewage treatment plants contains S and Cl elements. When the sludge is mixed with the waste incinerator, it will produce SO2 and HCl acid gases, which will increase the emission concentration of acid gases in the flue gas at the end of the waste incineration, thereby increasing the unit consumption of deacidification materials. In the current sludge and waste incineration coordinated disposal projects, the sludge is mixed with the furnace after drying. The drying process is a physical process without any pre-deacidification measures. The deacidification reaction is completed in the back-end flue gas treatment stage, which increases the deacidification load of the waste incineration power plant compared to the non-mixed sludge. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a fly ash and sludge coordinated recycling system and method with high recovery rate and low energy consumption in view of the deficiencies in the prior art.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A fly ash and sludge cooperative recycling system, comprising a screening unit, a crushing unit, a negative pressure conveying unit, a quantitative feeding unit, a sludge drying unit and a rotating dispersion unit connected in sequence;

[0006] The screening unit is used to screen the original fly ash into coarse ash and fine ash, the particle size of the coarse ash is greater than 75 μm, the particle size of the fine ash is less than 75 μm, and the fine ash enters the crushing unit;

[0007] The crushing unit is used to crush fine ash to obtain ultrafine ash, and the particle size of the ultrafine ash is ≤15μm;

[0008] The negative pressure conveying unit is used to convey the ultrafine ash to the quantitative feeding unit;

[0009] The quantitative feeding unit is used to quantitatively add the ultrafine ash into the sludge drying unit;

[0010] The sludge drying unit is used to mix and dry the ultrafine ash and sludge to obtain a sludge mixture;

[0011] The rotary dispersing unit disperses the sludge mixture onto the garbage to be incinerated by means of a rotary action.

[0012] In the above-mentioned fly ash and sludge coordinated recycling system, preferably, the screening unit includes a coaxial gravity multi-stage screener, and adjacently arranged coarse ash hopper and fine ash hopper; the coaxial gravity multi-stage screener includes a multi-stage screen cylinder, a rotating shaft and a motor, the rotating shaft passes through the axis of the multi-stage screen cylinder, a bracket is provided on the rotating shaft, the multi-stage screen cylinder is fixed on the rotating shaft through the bracket, one end of the rotating shaft is connected to the motor, the first end of the multi-stage screen cylinder is provided with an ash inlet, and the second end is provided with an ash outlet; the multi-stage screen cylinder is obliquely installed on the open end of the fine ash hopper so that the second end is higher than the first end, and the ash outlet is located on the open end of the coarse ash hopper; a coarse ash unloading port is provided at the bottom of the coarse ash hopper, and a fine ash unloading port is provided at the bottom of the fine ash hopper, and the fine ash unloading port is connected to the crushing unit.

[0013] The above-mentioned fly ash and sludge coordinated recycling system, preferably, the multi-stage screen cylinder includes a primary screen cylinder, a secondary screen cylinder and a tertiary screen cylinder which are sequentially mounted from the inside to the outside, and the screen holes of the multi-stage screen cylinder are sequentially reduced from the inside to the outside; one end of the multi-stage screen cylinder is open, and the other end is closed, the open end of the primary screen cylinder extends out of the open end of the secondary screen cylinder, and the open end of the secondary screen cylinder extends out of the open end of the tertiary screen cylinder, the open end of each level of the screen cylinder is the ash outlet of the screen cylinder of that level, the closed ends of each level of the screen cylinder are flush, and the closed end of the primary screen cylinder is connected to the ash inlet through an original ash hopper.

[0014] The above-mentioned fly ash and sludge cooperative recycling system is preferably provided with a spiral ash scraper rotating with the rotating shaft in the original ash hopper; the inner wall of the first-stage screen cylinder is provided with a first-stage spiral blade extending along the axial direction; the inner wall of the second-stage screen cylinder is provided with a second-stage spiral blade extending along the axial direction; the inner wall of the third-stage screen cylinder is provided with a third-stage spiral blade extending along the axial direction.

[0015] In the above-mentioned fly ash and sludge coordinated recycling system, preferably, the first-stage screen cylinder is used to screen particles with a particle size greater than 300 μm, the second-stage screen cylinder is used to screen particles with a particle size greater than 150 μm, and the third-stage screen cylinder is used to screen particles with a particle size greater than 75 μm.

[0016] In the above-mentioned fly ash and sludge coordinated recycling system, preferably, the negative pressure conveying unit includes a buffer tank, a first negative pressure pipe and a second negative pressure pipe, the top of the buffer tank is provided with an air inlet and an air outlet, the air inlet is connected to the output end of the crushing unit through the first negative pressure pipe, the air outlet is connected to the primary air inlet of the waste incinerator through the second negative pressure pipe, and the bottom of the buffer tank is provided with an ultrafine ash unloading port, and the ultrafine ash unloading port is connected to the quantitative feeding unit.

[0017] In the above-mentioned fly ash and sludge cooperative recycling system, preferably, the sludge drying unit is a thin layer dryer, a steam inlet is provided at the top of the thin layer dryer, and a drain port is provided at the bottom of the thin layer dryer.

[0018] In the above-mentioned fly ash and sludge coordinated recycling system, preferably, the rotating dispersion unit includes a buffer chamber and a dispersion disk, the input end of the buffer chamber is connected to the output end of the thin layer dryer, the dispersion disk is rotatably installed at the bottom end of the buffer chamber, and a motor is provided at the top of the buffer chamber, the motor is connected to the dispersion disk through a rotating shaft, and the dispersion disk is circumferentially provided with a dispersion port.

[0019] In the above-mentioned fly ash and sludge coordinated recycling system, preferably, the crushing unit is a ball mill; the quantitative feeding unit includes a disc feed distributor and multiple quantitative feeders, the disc feed distributor is provided with multiple discharge ports, one of the discharge ports is connected to a quantitative feeder, and the quantitative feeder is connected to a sludge drying unit.

[0020] As a general inventive concept, the present invention also provides a method for the coordinated recycling of fly ash and sludge based on the above system, comprising the following steps:

[0021] S1. Using a screening unit to screen the original fly ash into coarse ash and fine ash;

[0022] S2, conveying the fine ash to a crushing unit for crushing to obtain ultrafine ash;

[0023] S3, using a negative pressure conveying unit to convey the ultrafine ash to a quantitative feeding unit, and controlling the amount of ultrafine ash added to the sludge drying unit through the quantitative feeding unit, so that the ultrafine ash and the sludge are mixed and dried in proportion to obtain a sludge mixture;

[0024] S4, using a rotating dispersing unit to evenly disperse the sludge mixture onto the garbage to be incinerated, and then putting the mixed garbage into the furnace for combustion.

[0025] In step S3, the mass ratio of the ultrafine ash to the sludge is 1:3-5.

[0026] In step S3, the mass ratio of the ultrafine ash to the sludge is 1:3.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] (1) The fly ash and sludge synergistic recycling system of the present invention screens and recovers fine ash with the highest content of effective component Ca(OH)2 through a screening unit, crushes and grinds the ash through a crushing unit to obtain ultrafine ash with fully exposed effective reactant Ca(OH)2, screens the ultrafine ash again through a negative pressure conveying unit, and then quantitatively adds the ultrafine ash to a sludge drying unit, mixes and dries the sludge in proportion, and then enters the furnace to be burned with garbage, so as to achieve the pretreatment effect of acidic substances in the sludge. After the ultrafine ash enters the furnace, the slaked lime in the ultrafine ash can also react with acidic gas in the furnace and flue to achieve the effect of purifying flue gas. It can be seen that the system of the present invention can perform multiple desulfurization and deacidification on the sludge and garbage co-burning process, so that the slaked lime and acidic substances are more fully contacted and reacted. The present invention greatly reduces the pressure of fly ash chelation and solidification and landfill of its products through effective recycling, improves the comprehensive utilization rate of slaked lime, and can reduce the consumption of slaked lime, a deacidification material, in the tail flue gas purification system by about 29%.

[0029] (2) The fly ash and sludge synergistic recycling system of the present invention directly mixes the ultrafine ash with the sludge for drying, and the Ca(OH)2 in the ultrafine ash reacts with the acidic components in the sludge. Furthermore, when the dried sludge containing ultrafine ash is mixed with garbage for burning, the unreacted Ca(OH)2 in the ultrafine ash continues to react with the acidic components in the flue gas generated by the incineration of the sludge and garbage. Compared with the existing method of using lime slurry spray to contact the flue gas for desulfurization and acid removal, the Ca(OH)2 in this system has more sufficient contact and reaction time with the acidic substances. Furthermore, after the fine ash is crushed, the effective components are exposed more thoroughly, and the specific surface area is increased, which can further improve the subsequent reaction efficiency and utilization rate with the acidic substances in the sludge and flue gas. The ultrafine ash is fed through a quantitative feeding unit, and the ratio of ultrafine ash to sludge can be adjusted, and the dryness and chemical reaction of the sludge at the back end can be controlled. The advantages are: the ultrafine ash and sludge are mixed and dried, which can make the mixing more complete. On the one hand, the dryness of the mixture is improved; on the other hand, the initial acid-base neutralization reaction occurs in the sludge mixing, and the reaction is exothermic, which increases the temperature of the mixture, which can reduce the energy consumption of drying sludge to a certain extent and save energy.

[0030] (3) The fly ash and sludge coordinated recycling system of the present invention can be directly connected to the existing fly ash collection equipment through the ash inlet at the front end, and the sludge mixture can be directly rotated and dispersed to the feed inlet of the waste incinerator in the factory through the rotating dispersion unit at the rear end, so that it can be dispersed and mixed incinerated immediately without adding separate sludge and waste mixing equipment, thus saving space and cost and facilitating the transformation of existing equipment.

[0031] (4) The fly ash and sludge coordinated recycling method of the present invention has the above advantages because it has specific technical features corresponding to the system of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the structure of the fly ash and sludge coordinated recycling system according to Example 1 of the present invention.

[0033] Figure 2 Schematic diagram of the structure of the coaxial gravity multi-stage screener in Example 1 of the present invention.

[0034] Figure 3 for Figure 2 A magnified schematic diagram of center A.

[0035] Figure 4 for Figure 2 Sectional view along line AA.

[0036] Figure 5 Schematic diagram of the disassembled structure of the multi-stage screen cylinder in Example 1 of the present invention.

[0037] Figure 6 It is an enlarged schematic diagram of the ball mill in Example 1 of the present invention.

[0038] Figure 7 It is an enlarged schematic diagram of the negative pressure delivery unit in Example 1 of the present invention.

[0039] Figure 8 This is a schematic diagram of the reaction principle of ultrafine ash and sludge in a thin layer dryer in Example 1 of the present invention.

[0040] Fig. 9 Schematic diagram comparing the treatment of sludge mixture and pure sludge by the rotary separation unit in Example 1 of the present invention.

[0041] Legend: 1. Screening unit; 01. Rotating shaft; 011. Bracket; 02. Motor; 03. Ash inlet; 04. Ash outlet; 05. Ash hopper; 051. Spiral ash scraper; 06. Steel ball; 11. Coaxial gravity multi-stage screener; 111. Primary screen cylinder; 1111. Primary spiral blade; 112. Secondary screen cylinder; 1121. Secondary spiral blade; 113. Third-stage screen cylinder; 1131. Third-stage spiral blade Rotary vane; 12. coarse ash hopper; 13. fine ash hopper; 2. crushing unit; 3. negative pressure conveying unit; 31. buffer tank; 311. air inlet; 312. air outlet; 32. first negative pressure pipe; 33. second negative pressure pipe; 4. quantitative feeding unit; 41. disc feeding distributor; 42. quantitative feeder; 5. sludge drying unit; 6. rotary dispersion unit; 61. buffer chamber; 62. dispersion disc; 621. dispersion port. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0043] Example 1

[0044] Figure 1 A specific embodiment of the fly ash and sludge cooperative recycling system of the present invention is shown, comprising a screening unit 1, a crushing unit 2, a negative pressure conveying unit 3, a quantitative feeding unit 4, a sludge drying unit 5 and a rotating dispersion unit 6 connected in sequence;

[0045] Screening unit 1 is used to screen the original fly ash into coarse ash and fine ash. The particle size of coarse ash is greater than 75 μm, and the particle size of fine ash is less than 75 μm. The fine ash enters crushing unit 2;

[0046] The crushing unit 2 is used to crush the fine ash to obtain ultrafine ash, and the particle size of the ultrafine ash is ≤15μm;

[0047] The negative pressure conveying unit 3 is used to convey the ultrafine ash to the quantitative feeding unit 4;

[0048] The quantitative feeding unit 4 is used to quantitatively add the ultrafine ash to the sludge drying unit 5;

[0049] The sludge drying unit 5 is used to mix and dry the ultrafine ash and sludge to obtain a sludge mixture;

[0050] The rotary dispersing unit 6 disperses the sludge mixture onto the garbage to be incinerated by means of a rotary action.

[0051] The working process of the fly ash and sludge cooperative recycling system of this embodiment is as follows:

[0052] In view of the fly ash directly chelated and solidified for landfill treatment in the prior art, this embodiment screens the original fly ash collected after the flue gas purification treatment of the waste incineration power plant into coarse ash and fine ash through the screening unit 1, and recovers the fine ash, which is crushed and ground by the crushing unit 2 to remove CaSO4, CaSO3, CaCl2 and metal oxides on the surface of the fine ash particles, exposing the effective target Ca(OH)2 inside to obtain ultrafine ash, and then screened for the second time by the negative pressure conveying unit 3, and the ultrafine ash with high Ca(OH)2 content is conveyed to the quantitative feeding unit 4, and the ultrafine ash is controlled by the quantitative feeding unit 4 to enter the sludge drying unit 5, so that the ultrafine ash and sludge are mixed and dried in proportion, and then evenly dispersed on the garbage through the rotating dispersion unit 6, and mixed with the garbage into the furnace for incineration. The system of this embodiment recovers the effective components in the fly ash and mixes them with the sludge before burning them with garbage, thereby achieving the effect of pre-treating the acidic components of the sludge and greatly reducing the pressure of fly ash solidification and landfill of its products, reducing the consumption of deacidification materials in the tail flue gas purification system by about 29%, and improving the comprehensive utilization rate of slaked lime.

[0053] The test shows that compared with fly ash of other particle sizes, the content of effective target Ca(OH)2 in the obtained fine ash is the highest. The test results are shown in the following table:

[0054] Table 1 Ca(OH)2 content and alkalinity in fly ash particles of different particle sizes

[0055]

[0056] In this embodiment, the ultrafine ash is directly mixed with the sludge for drying, and the Ca(OH)2 in the ultrafine ash reacts with the acidic components in the sludge. Furthermore, when the dried sludge containing ultrafine ash is mixed with garbage for burning, the unreacted Ca(OH)2 in the ultrafine ash continues to react with the acidic components in the flue gas produced by the mixed burning. Compared with the existing method of using lime slurry spray to contact the flue gas for desulfurization and acid removal, the Ca(OH)2 in this system has more sufficient contact and reaction time with the acidic substances. Furthermore, after the fine ash is crushed, the effective components are exposed more thoroughly, and the specific surface area is increased, which can further improve the subsequent reaction efficiency and utilization rate with the acidic substances in the sludge and flue gas. The ultrafine ash is fed through the quantitative feeding unit 4, and the ratio of ultrafine ash to sludge can be adjusted, and the dryness and chemical reaction of the rear-end sludge can be regulated. Specifically, the ultrafine ash and sludge are mixed and dried, which can make the mixing more complete. On the one hand, the dryness of the mixture is improved, and on the other hand, the initial acid-base neutralization reaction of the sludge mixing occurs and releases heat, which increases the temperature of the mixture, and can reduce the energy consumption of drying the sludge to a certain extent.

[0057] Further improvement, such as Figure 2 , Figure 3 As shown, in this embodiment, the screening unit 1 includes a coaxial gravity multi-stage screener 11, a coarse ash hopper 12 and a fine ash hopper 13 arranged adjacently; the coaxial gravity multi-stage screener 11 includes a multi-stage screen cylinder, a rotating shaft 01 and a motor 02, the rotating shaft 01 passes through the axis of the multi-stage screen cylinder, a bracket 01 is provided on the rotating shaft 01, the multi-stage screen cylinder is fixed on the rotating shaft 01 through the bracket 011, one end of the rotating shaft 01 is connected to the motor 02, the first end of the multi-stage screen cylinder is provided with an ash inlet 03, and the second end is provided with an ash outlet 04; the multi-stage screen cylinder is obliquely installed on the open end of the fine ash hopper 13, so that the second end is higher than the first end, and the ash outlet 04 is located on the open end of the coarse ash hopper 12; a coarse ash unloading port is provided at the bottom of the coarse ash hopper 12, and a fine ash unloading port is provided at the bottom of the fine ash hopper 13, and the fine ash unloading port is connected to the crushing unit 2. The screening unit 1 of this embodiment adopts a multi-stage coaxial design and relies on gravity screening during screening. The multi-stage design can improve the purity of fine ash and make the proportion of particles with standard particle size as large as possible. The coaxial design and gravity screening can save equipment space and reduce screening power consumption while extending the screening time and improving the screening effect.

[0058] Further improvement, such as Figure 3 , Figure 4As shown, in this embodiment, the multi-stage screen cylinder includes a primary screen cylinder 111, a secondary screen cylinder 112 and a tertiary screen cylinder 113 which are sequentially mounted from the inside to the outside, and the sieve holes of the multi-stage screen cylinder decrease sequentially from the inside to the outside; one end of the multi-stage screen cylinder is open, and the other end is closed, the open end of the primary screen cylinder 111 extends out of the open end of the secondary screen cylinder 112, and the open end of the secondary screen cylinder 112 extends out of the open end of the tertiary screen cylinder 113, the open end of each stage of the screen cylinder is the ash outlet 04 of the screen cylinder of that stage, the closed ends of each stage of the screen cylinder are flush, and the closed end of the primary screen cylinder 111 is connected to the ash inlet 03 through a raw ash hopper 05.

[0059] The motor 02 and the rotating shaft 01 drive the multi-stage screen cylinder to rotate, and the original fly ash enters the original ash hopper 05 through the ash inlet 03. When passing through the rotating first-stage screen cylinder 111, the fly ash particles smaller than the first-stage screen holes fall into the second-stage screen cylinder 112 under the action of gravity, and the remaining fly ash particles fall into the coarse ash hopper 12 from the open end of the first-stage screen cylinder 111; during the rotation process, the fly ash particles smaller than the second-stage screen holes fall into the third-stage screen cylinder 113 under the action of gravity, and the remaining fly ash particles fall into the coarse ash hopper 12 from the open end of the second-stage screen cylinder 112; during the rotation process, the fly ash particles smaller than the third-stage screen holes fall into the fine ash hopper 13 under the action of gravity, and the remaining fly ash particles fall into the coarse ash hopper 12 from the open end of the third-stage screen cylinder 113, thereby realizing the three-stage screening of the original fly ash particles, which can greatly improve the screening rate of fine ash. Of course, more levels of screening cylinders can also be designed when necessary.

[0060] Further improvement, such as Figure 5 As shown, in this embodiment, the original ash hopper 05 is provided with a spiral ash scraper 051 rotating with the rotating shaft 01; the inner wall of the primary screen cylinder 111 is provided with a primary spiral sheet 1111 extending in the axial direction; the inner wall of the secondary screen cylinder 112 is provided with a secondary spiral sheet 1121 extending in the axial direction; the inner wall of the tertiary screen cylinder 113 is provided with a tertiary spiral sheet 1131 extending in the axial direction. The spiral ash scraper 051 and the spiral sheets of each level extending in the axial direction can effectively push the fly ash particles in each level of the screen cylinder to move upward along the screen to the ash outlet 04 during the rotation of the multi-level screen cylinder, so as to promote the fly ash particles of different particle sizes to be quickly dispersed in the corresponding screen cylinder, which is conducive to improving the screening efficiency.

[0061] Further improved, in this embodiment, the first-stage screen cylinder 111 is used to screen particles with a particle size greater than 300 μm, the second-stage screen cylinder 112 is used to screen particles with a particle size greater than 150 μm, and the third-stage screen cylinder 113 is used to screen particles with a particle size greater than 75 μm. The mesh holes of each level of the screen cylinder in this embodiment are reasonably designed, and the fine ash obtained by screening accounts for 93.45% of the original ash mass ratio, and the fine ash yield is high.

[0062] Further improvement, such as Figure 6As shown, in this embodiment, the crushing unit 2 is a ball mill. The use of a ball mill for crushing can more effectively peel off impurities such as CaSO4, CaSO3, CaCl2 and metal oxides on the surface of the particles, and the crushing effect is better.

[0063] Further improvement, such as Figure 7 As shown, in this embodiment, the negative pressure conveying unit 3 includes a buffer tank 31, a first negative pressure pipe 32 and a second negative pressure pipe 33. The top of the buffer tank 31 is provided with an air inlet 311 and an air outlet 312. The air inlet 311 is connected to the output end of the crushing unit 2 through the first negative pressure pipe 32, and the air outlet 312 is connected to the primary air inlet of the garbage incinerator through the second negative pressure pipe 33. The bottom of the buffer tank 31 is provided with an ultra-fine ash discharge port, which is connected to the quantitative feeding unit 4. Fine ash enters the crushing unit 2, and ultra-fine ash is output from the crushing unit 2, and both are transported through the negative pressure air source at the inlet of the primary fan, thereby reducing the power energy consumption of the newly added equipment of this system.

[0064] Further improved, in this embodiment, the sludge drying unit 5 is a thin layer dryer such as a cylindrical thin layer dryer, the upper part of the thin layer dryer is provided with a steam inlet, and the lower part of the thin layer dryer is provided with a drain port. The ultra-fine ash is mixed with the sludge in the thin layer dryer to improve the sludge dryness, and the ultra-fine ash is fully in contact with the sludge in the thin layer dryer, which is conducive to the initial acid-base neutralization reaction, such as Figure 8 shown.

[0065] Further improved, in this embodiment, the rotating dispersion unit 6 includes a buffer chamber 61 and a dispersion disk 62, the input end of the buffer chamber 61 is connected to the output end of the thin layer drying machine, the dispersion disk 62 is rotatably installed at the bottom of the buffer chamber 61, the top of the buffer chamber 61 is provided with a motor 02, the motor 02 is connected to the dispersion disk 62 through a rotating shaft 01, and the dispersion disk 62 is circumferentially provided with a dispersion port 621. Fig. 9 As shown, compared with pure sludge, the sludge mixture has relatively lower viscosity, looser texture, better separation effect, can be split into small clusters during rotation separation, has a larger range of throwing out, is distributed more widely and evenly on the garbage, and is not easy to gather into clusters.

[0066] As a further improvement, in this embodiment, the quantitative feeding unit 4 includes a disc feed distributor 41 and multiple quantitative feeders 42, the disc feed distributor 41 is provided with multiple discharge ports, one discharge port is connected to one quantitative feeder 42, and one quantitative feeder 42 is connected to one sludge drying unit 5. In this embodiment, the disc feed distributor 41 cooperates with multiple quantitative feeders 42 to achieve ultrafine ash mixed with sludge in multiple thin-layer dryers, thereby improving overall work efficiency.

[0067] In order to fully illustrate the scheme and advantages of this embodiment, the working process of the fly ash and sludge coordinated recycling system of this embodiment is further described as follows:

[0068] The original fly ash enters the coaxial multi-stage gravity screener 11 through the ash inlet 03. Driven by the motor 02, the rotating shaft 01 drives the ash scraper, the first-level screen cylinder 111, the first-level spiral sheet 1111, the second-level screen cylinder 112, the second-level spiral sheet 1121, the third-level screen cylinder 113, and the third-level spiral sheet 1131 to rotate synchronously. The power transmission and structural support are realized by the bracket 011. After the original fly ash enters the original ash hopper 05, it enters the first-level screen cylinder under the action of the spiral ash scraper 051. In the sieve drum 111, the particles with a particle size larger than 300 μm in the original fly ash cannot pass through the primary screen drum 111, and advance in spiral under the push of the primary spiral blade 1111, and finally fall into the coarse ash hopper 12 from the ash outlet 04. The particles with a particle size less than or equal to 300 μm pass through the primary screen drum 111 under the action of gravity and fall into the secondary screen drum 112. The particles with a particle size larger than 150 μm that fall into the secondary screen drum 112 fall out of the ash outlet 04 under the action of the secondary spiral blade 1121. The particles with a diameter of less than or equal to 150 μm pass through the secondary screen cylinder 112 under the action of gravity and fall into the tertiary screen cylinder 113. The particles with a diameter of more than 75 μm that fall into the tertiary screen cylinder 113 fall into the coarse ash hopper 12 from the ash outlet 04 under the action of the tertiary spiral sheet 1131. The particles with a diameter of less than or equal to 75 μm pass through the tertiary screen cylinder 113 under the action of gravity and fall into the fine ash hopper 13. This process realizes the multi-stage screening of the original fly ash, and the obtained The mass ratio of fine ash particles to original fly ash is 93.45%. The fine ash in the fine ash hopper 13 enters the ball mill under the action of wind. In the ball mill, the steel balls 06 collide with each other to grind the fine ash into ultrafine ash. After the ultrafine ash is crushed, CaSO4, CaSO3, CaCl2, and metal oxides on the surface are removed to expose the effective target Ca(OH)2 inside. At the same time, the ultrafine ash has a smaller particle size and a larger specific surface area, which is more conducive to the subsequent reaction process. The buffer tank 31, the first negative pressure pipe 32 and the second negative pressure pipe 33 constitute a negative pressure conveying system. The primary fan inlet provides a negative pressure head. The ground ultrafine ash enters the buffer tank 31. Lighter dust, metal oxides and other finer particles enter the incinerator through the second negative pressure pipe 33 under the negative pressure of the primary fan. Slightly larger particles containing the effective target Ca(OH)2 settle to the bottom of the buffer tank 31. A disc feed distributor 41 is provided at the bottom of the buffer tank 31. The disc feed distributor 41 distributes the ultrafine ash to four quantitative feeders 42. Each quantitative feeder 42 is connected to a thin layer dryer. The feeding frequency of the quantitative feeder 42 is adjusted according to the sludge input of the thin layer dryer to ensure that the ratio of sludge and ash is appropriate. After quantitative feeding, the ultrafine ash enters the thin-layer dryer and mixes with the sludge in the thin-layer dryer. Because the ultrafine ash does not contain moisture, it can increase the dryness of the mixture after mixing with the sludge. At the same time, the alkaline substances such as Ca(OH)2 in the ultrafine ash react with the acidic substances in the sludge to release heat and increase the temperature of the mixture.The fully mixed mortar mixture enters the buffer chamber 61, and the motor 02 drives the dispersion disk 62 to rotate through the rotating shaft 01. The mortar mixture falls from the buffer chamber 61 onto the dispersion disk 62, rotates with the dispersion disk 62, and separates from the dispersion disk 62 under the action of centrifugal force, scatters to the surroundings, falls on the garbage, and is evenly spread on the garbage.

[0069] The system advantages of the present invention can be further demonstrated by the following data:

[0070] (1) Investigation on saving slaked lime

[0071] When the system of this embodiment crushes fine ash into ultrafine ash, the total mass and Ca(OH)2 content changes can be ignored. The Ca(OH)2 content in the ultrafine ash is 31.65%. Then, for every ton of original fly ash recovered, the mass of Ca(OH)2 obtained is

[0072] m=1*93.45%*31.65%=0.29t

[0073] This part of Ca(OH)2 reacts with the acidic substances in the sludge when mixed with the sludge and dried. The sludge mixture reacts with the acidic substances in the flue gas of the incinerator. Its utilization rate is not lower than the utilization rate of slaked lime in the flue gas purification system (35%). According to conservative estimates, the amount of slaked lime that can be saved is at least

[0074] M=0.29*35% / 35%=0.29t

[0075] It can be understood that the use of the system of the present invention to recycle and reuse the original fly ash can reduce the consumption of slaked lime, a deacidification material, in the tail flue gas purification system by about 29%.

[0076] In actual application, taking the daily processing scale of the applicant's plant as an example, recycling 50t of raw fly ash every day can save at least

[0077] 50*0.29=14.5t

[0078] There are 4 garbage incinerators running in the factory at the same time, each of which processes 850 tons of garbage per day. The flue gas generated by each ton of garbage requires 12kg of slaked lime for purification, so the total daily consumption of slaked lime is 850*12*4=40.8t. By recycling 50t of original fly ash every day, 14.5t of slaked lime can be saved, and the saving is 14.5t / 40.8t=35.5%, which is equivalent to reducing the consumption of slaked lime for deacidification material in the tail flue gas purification system by about 35.5% every day.

[0079] (2) Investigation of steam consumption for drying sludge

[0080] Take the mixing of ultrafine ash and sludge at a mass ratio of 1:3 as an example. Before mixing, the sludge dryness is 20%, the ultrafine ash dryness is 100%, and the dryness after mixing is

[0081] (20%*3+100%*1) / (1+3)=40%

[0082] Therefore, mixing at a mass ratio of 1:3 can increase the dryness of the sludge from 20% to 40%.

[0083] According to experimental data, the temperature of ultrafine ash and sludge rises after mixing. If they are mixed at a mass ratio of 1:3, the temperature can rise by 11°C. The experimental results are shown in the following table:

[0084] Table 2 Temperature changes before and after mixing of ultrafine ash and sludge

[0085] Initial temperature(℃) Dosage(g) Dosage(g) sludge 23.5 150 150 Ultrafine ash 41 30 50 Mixing ratio of ultrafine ash and sludge —— 1∶3 1∶5 Temperature before mixing reaction (℃) 23.5 23.5 Temperature after mixed reaction (℃) —— 31.5 34.5 Plaster mix heating temperature (℃) —— 8 11

[0086] Note: The temperature before the mixing reaction is the temperature before the chemical reaction occurs between the ultrafine ash and the sludge; the temperature after the mixing reaction is the temperature after the chemical reaction occurs between the ultrafine ash and the sludge.

[0087] For pure sludge entering the dryer, steam heats the sludge temperature from 30°C to 95°C. The steam consumption per ton of sludge is about 0.45t / t. The steam consumed for 1 ton of ultra-fine ash is

[0088] 3*0.45=1.35

[0089] Then the steam required to increase the sludge temperature by 1°C is

[0090] 1.35 / (95-30)=0.0207

[0091] According to the temperature rise of 11℃ after ultrafine ash and sludge are mixed in a mass ratio of 1:3, the amount of steam saved is

[0092] 0.0207*11=0.228

[0093] Reduced steam consumption

[0094] 0.228 / 1.35*100%=16.9%

[0095] That is, by adopting the system of the present invention, 16.9% of steam can be saved for every ton of ultrafine ash recycled, and 16.9%*93.45%=15.8% of steam can be saved for every ton of original fly ash recycled.

[0096] Example 2

[0097] A method for the coordinated recycling of fly ash and sludge based on the system of Example 1 comprises the following steps:

[0098] S1, using screening unit 1 to screen the original fly ash into coarse ash and fine ash;

[0099] S2, transporting the fine ash to the crushing unit 2 for crushing to obtain ultrafine ash;

[0100] S3, using the negative pressure conveying unit 3 to convey the ultrafine ash to the quantitative feeding unit 4, and controlling the amount of ultrafine ash added to the sludge drying unit 5 through the quantitative feeding unit 4, so that the ultrafine ash and the sludge are mixed and dried in proportion to obtain a sludge mixture;

[0101] S4, using the rotating dispersing unit 6 to evenly mix the mortar mixture with the garbage, and then putting the mixed garbage into the furnace for combustion.

[0102] This embodiment can not only recover the excess slaked lime in the fly ash and reduce the consumption of deacidification materials in the tail flue gas purification system by about 29%, improve the comprehensive utilization rate of slaked lime, but also reduce the processing pressure of fly ash chelation solidification and landfill by sorting out the unreacted slaked lime and reacting it with SO2 and HCl acid gases in the sludge.

[0103] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the spirit and technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention still fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A fly ash and sludge cooperative recycling system, characterized in that: It comprises a screening unit (1), a crushing unit (2), a negative pressure conveying unit (3), a quantitative feeding unit (4), a sludge drying unit (5) and a rotating dispersion unit (6) which are connected in sequence; The screening unit (1) is used to screen the original fly ash into coarse ash and fine ash, the particle size of the coarse ash is greater than 75 μm, the particle size of the fine ash is less than 75 μm, and the fine ash enters the crushing unit (2); The crushing unit (2) is used to crush fine ash to obtain ultrafine ash, wherein the particle size of the ultrafine ash is ≤15 μm; The negative pressure conveying unit (3) is used to convey the ultra-fine ash to the quantitative feeding unit (4); The quantitative feeding unit (4) is used to quantitatively add the ultrafine ash to the sludge drying unit (5); The sludge drying unit (5) is used to mix and dry the ultrafine ash and sludge to obtain a sludge mixture; The rotating dispersing unit (6) disperses the sludge mixture onto the garbage to be incinerated by means of a rotating action.

2. The fly ash and sludge coordinated recycling system according to claim 1 is characterized in that: The screening unit (1) comprises a coaxial gravity multi-stage screener (11), a coarse ash hopper (12) and a fine ash hopper (13) arranged adjacent to each other; the coaxial gravity multi-stage screener (11) comprises a multi-stage screen cylinder, a rotating shaft (01) and a motor (02); the rotating shaft (01) passes through the axis of the multi-stage screen cylinder; a bracket (011) is provided on the rotating shaft (01); the multi-stage screen cylinder is fixed to the rotating shaft (01) via the bracket (011); one end of the rotating shaft (01) is connected to the motor The multi-stage screen cylinder is connected to a crushing unit (02), the first end of the multi-stage screen cylinder is provided with an ash inlet (03), and the second end is provided with an ash outlet (04); the multi-stage screen cylinder is obliquely installed on the open end of the fine ash hopper (13), so that the second end is higher than the first end, and the ash outlet (04) is located on the open end of the coarse ash hopper (12); the bottom of the coarse ash hopper (12) is provided with a coarse ash unloading port, and the bottom of the fine ash hopper (13) is provided with a fine ash unloading port, and the fine ash unloading port is connected to the crushing unit (2).

3. The fly ash and sludge coordinated recycling system according to claim 2 is characterized in that: The multi-stage screen cylinder comprises a primary screen cylinder (111), a secondary screen cylinder (112) and a tertiary screen cylinder (113) which are sequentially mounted from the inside to the outside, and the screen holes of the multi-stage screen cylinder are sequentially reduced from the inside to the outside; one end of the multi-stage screen cylinder is open and the other end is closed, the open end of the primary screen cylinder (111) extends out of the open end of the secondary screen cylinder (112), and the open end of the secondary screen cylinder (112) extends out of the open end of the tertiary screen cylinder (113), the open end of each stage of the screen cylinder is the ash outlet (04) of the sieve cylinder of that stage, the closed ends of each stage of the screen cylinder are flush, and the closed end of the primary screen cylinder is connected to the ash inlet (03) through an original ash hopper (05).

4. The fly ash and sludge coordinated recycling system according to claim 3 is characterized in that: The raw ash hopper (05) is provided with a spiral ash scraper (051) that rotates with the rotating shaft (01); the inner wall of the first-stage screen cylinder (111) is provided with a first-stage spiral sheet (1111) extending along the axial direction; the inner wall of the second-stage screen cylinder (112) is provided with a second-stage spiral sheet (1121) extending along the axial direction; and the inner wall of the third-stage screen cylinder (113) is provided with a third-stage spiral sheet (1131) extending along the axial direction.

5. The fly ash and sludge coordinated recycling system according to claim 3 is characterized in that: The first-stage screen cylinder (111) is used for screening particles with a particle size greater than 300 μm, the second-stage screen cylinder (112) is used for screening particles with a particle size greater than 150 μm, and the third-stage screen cylinder (113) is used for screening particles with a particle size greater than 75 μm.

6. The fly ash and sludge cooperative recycling system according to any one of claims 1 to 5, characterized in that: The negative pressure conveying unit (3) comprises a buffer tank (31), a first negative pressure pipe (32) and a second negative pressure pipe (33); an air inlet (311) and an air outlet (312) are provided at the top of the buffer tank (31); the air inlet (311) is connected to the output end of the crushing unit (2) via the first negative pressure pipe (32); the air outlet (312) is connected to the primary air inlet of the waste incinerator via the second negative pressure pipe (33); an ultrafine ash discharge port is provided at the bottom of the buffer tank (31); and the ultrafine ash discharge port is connected to the quantitative feeding unit (4).

7. The fly ash and sludge cooperative recycling system according to any one of claims 1 to 5, characterized in that: The sludge drying unit (5) is a thin layer dryer, a steam inlet is provided at the top of the thin layer dryer, and a drain port is provided at the bottom of the thin layer dryer.

8. The fly ash and sludge cooperative recycling system according to any one of claims 1 to 5, characterized in that: The rotating dispersion unit (6) comprises a buffer chamber (61) and a dispersion disk (62), wherein the input end of the buffer chamber (61) is connected to the output end of the thin layer drying machine, and the dispersion disk (62) is rotatably mounted at the bottom end of the buffer chamber (61). A motor (02) is provided at the top of the buffer chamber (61), and the motor (02) is connected to the dispersion disk (62) via a rotating shaft (01). The dispersion disk (62) is circumferentially provided with a dispersion port (621).

9. The fly ash and sludge cooperative recycling system according to any one of claims 1 to 5, characterized in that: The crushing unit (2) is a ball mill; the quantitative feeding unit (4) comprises a disc-type feeding distributor (41) and a plurality of quantitative feeders (42); the disc-type feeding distributor (41) is provided with a plurality of discharge ports, one of the discharge ports is connected to a quantitative feeder (42), and one of the quantitative feeders (42) is connected to a sludge drying unit (5).

10. A method for the coordinated recycling of fly ash and sludge based on the system according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, using a screening unit (1) to screen the raw fly ash into coarse ash and fine ash; S2, conveying the fine ash to a crushing unit (2) for crushing to obtain ultrafine ash; S3, using a negative pressure conveying unit (3) to convey the ultrafine ash to a quantitative feeding unit (4), and controlling the amount of ultrafine ash added to a sludge drying unit (5) through the quantitative feeding unit (4), so that the ultrafine ash and the sludge are mixed and dried in proportion to obtain a sludge mixture; S4, using a rotating dispersing unit (6) to evenly disperse the sludge mixture onto the garbage to be incinerated, and then putting the mixed garbage into the furnace for combustion.

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