Multi-stage separation system and multi-stage separation method for fly ash

Abstract

The multi-stage separation system comprises an original ash silo, a first-stage ash silo, a second-stage ash silo and a third-stage ash silo, ash raw materials are placed in the original ash silo, the first-stage ash silo is used for placing first-stage fine ash, the second-stage ash silo is used for placing second-stage fine ash, and the third-stage ash silo is used for placing coarse ash. A sorting machine is arranged at a third-stage ash feeding port of the third-stage ash silo, a cyclone separator is arranged at a feeding port of the first-stage ash silo, a feeding port of the second-stage ash silo is communicated with an ash collecting box at the bottom of the cyclone separator through a sorting guide part, and an original ash discharging port of the original ash silo, the sorting machine, the cyclone separator and the fan are communicated through a conveying pipeline; according to the device, the first-stage ash silo and the second-stage ash silo are arranged, and the ash collecting box arranged on the first-stage ash silo is communicated with the second-stage ash silo through the sorting guide part, so that sorting operation on the fine ash can be realized, the first-stage fine ash and the second-stage fine ash with two different finenesses can be sorted and collected, and the coal ash can be fully and effectively utilized.

Description

Technical Field

[0001] This invention relates to the field of powder material sorting technology, specifically to a multi-stage sorting system and method for fly ash. Background Technology

[0002] The large amount of fly ash produced by coal-fired power generation can be transformed into valuable resources after grading and sorting, such as being used as filler in cement production. After being separated according to particle size, the fine fly ash is one of the raw materials for cement production, greatly increasing its economic value. Grade I fine fly ash can be directly supplied to concrete mixing plants as a raw material for high-grade concrete, improving its fluidity; Grade II fine fly ash can be used as a raw material for foundation cement; and the remaining coarse fly ash can be used to make bricks or as roadbed material.

[0003] Existing fly ash sorting devices generally only sort fly ash into two products, coarse ash and fine ash, based on the set fine ash particle size specifications. They cannot further sort the fine ash, which means that the fine ash in the fine ash silo needs to be further separated in the future, otherwise the fly ash cannot be effectively utilized.

[0004] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0005] To address the aforementioned technical deficiencies, the present invention provides a multi-stage fly ash sorting system, comprising a raw ash silo, a primary ash silo, a secondary ash silo, and a tertiary ash silo. The raw ash silo contains raw ash materials. The primary ash silo contains primary fine ash, the secondary ash silo contains secondary fine ash, and the tertiary ash silo contains coarse ash. A sorting machine is installed at the tertiary ash inlet of the tertiary ash silo. A cyclone separator is installed at the primary ash inlet of the primary ash silo. The secondary ash inlet of the secondary ash silo is connected to the ash collection box at the bottom of the cyclone separator via a sorting guide. The raw ash outlet of the raw ash silo, the sorting machine, the cyclone separator, and the blower are connected via a conveying pipeline.

[0006] Preferably, the conveying pipeline includes a first conveying pipeline, a second conveying pipeline, a connecting pipeline, and a return pipeline. The output port of the blower is connected to the sorting inlet of the separator through the first conveying pipeline. The raw ash outlet of the raw ash silo is located on the first conveying pipeline. The output port of the blower is connected to the secondary damper of the separator through the second conveying pipeline. The coarse outlet at the bottom of the separator is connected to the tertiary ash inlet of the tertiary ash silo. The fine outlet of the separator is connected to the separation inlet of the cyclone separator through the connecting pipeline. The gas outlet of the cyclone separator is connected to the blower through the return pipeline, thereby forming a closed-loop conveying pipeline.

[0007] Preferably, the conveying pipeline further includes a waste gas pipeline, the two ends of which are respectively connected to the upper part of the first conveying pipeline and the primary ash silo. The waste gas pipeline is equipped with a regulating butterfly valve to control the opening and closing of the waste gas pipeline.

[0008] Preferably, the sorting guide includes an air inclined trough, the two ends of which are respectively connected to the top of the ash collection box and the top of the secondary ash silo, and the air inclined trough is inclined from the top of the ash collection box to the top of the secondary ash silo from high to low.

[0009] Preferably, a blower is provided on the air inclined duct to provide transport power for the fine ash inside the air inclined duct.

[0010] Preferably, the lower part of the ash collection box is provided with an ash collection section, which is configured as a funnel-shaped structure with a cross-section that gradually decreases from top to bottom. The bottom of the ash collection section is connected to the top of the primary ash silo through a first ash discharge pipe. A second ash discharge pipe is provided on the side of the ash collection section. One end of the second ash discharge pipe is connected to the interior of the ash collection section, and the other end is connected to the upper end of the air inclined trough pipe. The secondary fine ash in the ash collection section enters the air inclined trough pipe through the second ash discharge pipe. A first pneumatic gate valve is provided on the first ash discharge pipe, and a second pneumatic gate valve is provided on the second ash discharge pipe.

[0011] Preferably, a dust suction pipe is provided on the top of the secondary ash silo. The dust suction pipe is U-shaped, with one end connected to the secondary ash silo and the other end connected to the lower end of the air chute. The dust suction pipe is also provided with a sealable inspection and unblocking hole, which is located at the lower end of the air chute.

[0012] Preferably, a filter plate is provided inside the ash collection section, the filter plate divides the interior of the ash collection section into an upper ash chamber and a lower ash chamber distributed vertically, the filter plate is provided with filter holes, the upper ash chamber and the lower ash chamber are connected only through the filter holes, the filter plate is located below the connection between the second lower ash pipe and the ash collection section, and above the first lower ash pipe.

[0013] Preferably, the ash collection box is also equipped with a material level switch for monitoring the accumulation of the secondary fine ash in the upper ash chamber, and the material level switch is connected to the second pneumatic gate valve.

[0014] Preferably, a multi-stage fly ash sorting method employs the aforementioned multi-stage fly ash sorting system. The multi-stage fly ash sorting method includes a primary fine ash collection stage, a secondary fine ash collection stage, and a cleaning stage. In the secondary fine ash collection stage, the exhaust gas pipeline is closed, the raw ash outlet of the raw ash silo is opened, and feed is introduced into the first conveying pipeline. The ash raw material undergoes coarse and fine ash classification by the sorting machine. The classified coarse ash is discharged into the tertiary ash silo for collection, while the fine ash enters the cyclone separator for gas-ash separation. The separated fine ash falls into the ash collection box. The second pneumatic gate valve is opened, and the first pneumatic gate valve is closed. The primary fine ash enters the primary ash silo for collection via the first ash discharge pipe. The secondary fine ash... The ash accumulates in the ash collection box; when the accumulation of secondary fine ash in the ash collection box triggers the material level switch, the secondary fine ash collection stage begins. The raw ash outlet of the raw ash silo is closed and feeding into the first conveying pipe stops. The first pneumatic gate valve is opened, and the second pneumatic gate valve is closed. The secondary fine ash enters the secondary ash silo for collection through the air inclined pipe. After the secondary fine ash collection stage is completed, the cleaning stage begins. The raw ash outlet of the raw ash silo is closed and feeding into the first conveying pipe stops. The second pneumatic gate valve is opened, and the first pneumatic gate valve is closed. The exhaust gas pipe is opened. After the cleaning stage is completed, the primary fine ash collection stage begins again.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention is provided with two fine ash silos, namely the primary ash silo and the secondary ash silo, and the ash collection box set on the primary ash silo is connected to the secondary ash silo through the sorting guide, which can realize the sorting operation of fine ash, so as to sort and collect two kinds of fine ash with different fineness, namely primary fine ash and secondary fine ash, which facilitates the full and effective utilization of fly ash. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the multi-stage sorting system for fly ash.

[0017] Figure 2 This is a structural view of the sorting guide section;

[0018] Figure 3 This is a view of the connection structure of the ash collection box;

[0019] Figure 4 This is a structural view of the sorting machine.

[0020] The numbers in the diagram represent:

[0021] 1-Original ash silo; 2-Primary ash silo; 3-Secondary ash silo; 4-Tertiary ash silo; 5-Sorter; 6-Cyclone separator; 7-Fan; 8-Conveying pipeline; 9-Sorting guide; 11-Valve assembly; 12-Feeding device; 21-First ash discharge pipe; 22-First pneumatic gate valve; 41-Linger airlock valve; 51-Secondary air damper; 52-Original ash inlet pipe; 53-Vortex; 54-Fine ash outlet pipe; 55-Inner cylinder ; 56-Coarse ash outlet pipe; 57-Adjusting baffle; 61-Ash collection box; 62-Ash collection section; 63-Filter plate; 64-Material level switch; 81-First conveying pipe; 82-Second conveying pipe; 83-Connecting pipe; 84-Return pipe; 85-Exhaust air pipe; 91-Air inclined chute pipe; 92-Blower; 93-Second ash discharge pipe; 94-Second pneumatic gate valve; 95-Dust suction pipe; 96-Inspection and unblocking hole. Detailed Implementation

[0022] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0023] Example 1

[0024] like Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of the multi-stage fly ash sorting system of the present invention. The multi-stage fly ash sorting system of the present invention includes a raw ash silo 1, a primary ash silo 2, a secondary ash silo 3, and a tertiary ash silo 4. The raw ash silo 1 contains ash raw materials. The primary ash silo 2 is used to store primary fine ash. The secondary ash silo 3 is used to store secondary fine ash. The tertiary ash silo 4 is used to store coarse ash. A separator 5 is provided at the tertiary ash inlet of the tertiary ash silo 4. A cyclone separator 6 is provided at the primary ash inlet of the primary ash silo 2. The secondary ash inlet of the secondary ash silo 3 is connected to the ash collection box 61 at the bottom of the cyclone separator 6 through a sorting guide 9. The raw ash outlet of the raw ash silo 1, the separator 5, the cyclone separator 6, and the blower 7 are connected through a conveying pipeline 8.

[0025] The conveying pipeline 8 includes a first conveying pipeline 81, a second conveying pipeline 82, a connecting pipeline 83, and a return pipeline 84. The output port of the blower 7 is connected to the sorting inlet of the separator 5 through the first conveying pipeline 81. The raw ash outlet of the raw ash silo 1 is located on the first conveying pipeline 81, so that the ash raw material enters the separator 5 through the sorting inlet for coarse and fine separation. The output port of the blower 7 is connected to the secondary damper 51 of the separator 5 through the second conveying pipeline 82 to provide sorting power to the separator 5. The coarse outlet at the bottom of the separator 5 is connected to the tertiary ash inlet of the tertiary ash silo 4. The fine outlet of the separator 5 is connected to the separation inlet of the cyclone separator 6 through the connecting pipeline 83. The gas outlet of the cyclone separator 6 is connected to the blower 7 through the return pipeline 84, thereby forming a closed-loop conveying pipeline 8.

[0026] The conveying pipeline 8 also includes a waste gas pipeline 85, with its two ends connected to the first conveying pipeline 81 and the upper part of the primary ash silo 2, respectively. The exhaust gas containing trace amounts of dust in the conveying pipeline 8 can enter the primary ash silo 2 through the waste gas pipeline 85 and be purified and discharged by the dust collector installed in the primary ash silo 2. The waste gas pipeline 85 is equipped with a regulating butterfly valve to realize the opening and closing of the waste gas pipeline 85.

[0027] Preferably, the raw ash silo 1 is equipped with a valve assembly 11, including a manual valve, a pneumatic valve, and an electric airlock, at the raw ash discharge port. The manual valve and the pneumatic valve are used to control the opening and closing of the ash raw material flowing into the first conveying pipe 81, and the electric airlock is used to prevent the conveying gas in the first conveying pipe 81 from being conveyed into the raw ash silo 1.

[0028] Specifically, a feeding device 12 is installed at the lower unloading layer of the raw ash silo 1. Starting from the raw ash discharge port of the raw ash silo 1, a manual valve / pneumatic valve and a frequency conversion speed-regulating electric airlock feeder are installed. The feeder is installed on the system pipeline, and a manual butterfly valve is installed behind the material drop point of the system pipeline as a blow-blocking gate.

[0029] Preferably, the tertiary ash inlet of the tertiary ash silo 4 is equipped with a tongue plate airlock valve 41 as an airlock unloading device; the secondary air damper 51 of the separator 5 is equipped with an adjusting butterfly valve (manual / electric) to control the wind force entering the separator 5 through the secondary air damper 51.

[0030] The ash raw material is uniformly introduced into the first conveying pipe 81 through the manual valve, the pneumatic valve and the electric airlock, and is uniformly mixed with the negative pressure airflow in the conveying pipe 8 to form a gas-solid two-phase flow. The ash raw material enters the separator 5 under negative pressure, and is classified into coarse and fine ash under the action of gravity and centrifugal force. The classified coarse ash is discharged into the third-stage ash silo 4 through the tongue plate airlock valve 41. The fine ash is discharged from the fine discharge port of the two side volutes and enters the cyclone separator 6 with the airflow for gas-ash separation. The separated fine ash falls into the ash collection box 61. The exhaust gas containing trace amounts of dust returns to the first conveying pipe 81 through the return air pipe to form a closed loop. It can also enter the first-stage ash silo 2 through the exhaust gas pipe 85 in the first conveying pipe 81, and be purified and discharged by the dust collector installed in the first-stage ash silo 2.

[0031] The inlet of the fan 7 is equipped with a regulating damper, which is equipped with an electric actuator to adjust the conveying intensity in the conveying pipeline 8.

[0032] Generally, the cyclone separator 6 is a conventional two-stage cyclone separator to improve the gas-ash separation effect. Preferably, the separator 5 is a conventional separator in the prior art.

[0033] The present invention is provided with two fine ash silos, namely the primary ash silo 2 and the secondary ash silo 3. The ash collection box 61 set on the primary ash silo 2 is connected to the secondary ash silo 3 through the sorting guide part 9, so as to realize the sorting operation of fine ash, so as to sort and collect two kinds of fine ash with different fineness, namely primary fine ash and secondary fine ash, which facilitates the full and effective utilization of fly ash.

[0034] Example 2

[0035] like Figure 2 As shown, Figure 2 This is a structural view of the sorting guide section 9; the sorting guide section 9 includes an air inclined trough pipe 91, the two ends of which are connected to the top of the ash collection box 61 and the top of the secondary ash silo 3, respectively. The air inclined trough pipe 91 is inclined from the top of the ash collection box 61 to the top of the secondary ash silo 3, thereby facilitating the movement of fine ash from the ash collection box 61 into the secondary ash silo 3.

[0036] A blower 92 is installed on the air inclined pipe 91 to provide power for the fine ash in the air inclined pipe 91, so that the fine ash moves directionally from the ash collection box 61 to the secondary ash silo 3. The conveying medium of the air inclined pipe 91 is secondary fly ash (fineness of 14% to 25%).

[0037] like Figure 3 As shown, Figure 3This is a structural view of the ash collection box; the ash collection box 61 has an ash collection section 62 at its lower part. The ash collection section 62 is a funnel-shaped structure with a cross-section that gradually decreases from top to bottom. The bottom of the ash collection section 62 is connected to the top of the primary ash silo 2 through a first ash discharge pipe 21. A second ash discharge pipe 93 is provided on the side of the ash collection section 62. One end of the second ash discharge pipe 93 is connected to the interior of the ash collection section 62, and the other end is connected to the upper end of the air inclined trough pipe 91. The secondary fine ash in the ash collection section 62 enters the air inclined trough pipe 91 through the second ash discharge pipe 93. A first pneumatic gate valve 22 is provided on the first ash discharge pipe 21, and a second pneumatic gate valve 94 is provided on the second ash discharge pipe 93, to realize the opening and closing of the first ash discharge pipe 21 and the second ash discharge pipe 93, respectively.

[0038] Preferably, when using a two-stage cyclone separator, the lower part of the two-stage cyclone separator is provided with two ash collection boxes 61. The second ash discharge pipe 93 is configured as a three-way structure, with two inlet sections and one outlet section. The two inlet sections correspond to the two ash collection boxes 61 of the two-stage cyclone separator 6, and the outlet section is connected to the upper end of the air inclined pipe 91. The two inlet sections are each provided with a second pneumatic gate valve 94, so that the secondary fine ash in the two ash collection boxes 61 can be collected independently.

[0039] The top of the secondary ash silo 3 is equipped with a dust suction pipe 95, which is a U-shaped pipe. One end of the dust suction pipe 95 is connected to the secondary ash silo 3, and the other end is connected to the lower end of the air inclined pipe 91. The dust suction pipe 95 facilitates the rapid discharge of the conveying gas generated by the blower 92 and also greatly reduces the blockage of the secondary fine ash at the lower end of the air inclined pipe 91.

[0040] The suction pipe 95 is also provided with an inspection and unblocking hole 96, which is provided at the lower end of the air inclined pipe 91. It can be used to inspect and unblock the connection between the lower end of the air inclined pipe 91 and the secondary ash silo 3 to avoid blockage.

[0041] A filter plate 63 is provided inside the ash collection section 62, dividing the interior of the ash collection section 62 into an upper ash chamber and a lower ash chamber. The filter plate 63 is provided with filter holes, and the upper ash chamber and the lower ash chamber are connected only through the filter holes. The filter plate 63 is located below the connection between the second lower ash pipe 93 and the ash collection section 62, and above the first lower ash pipe 21. Through the filtration of the filter plate 63, the finer primary ash can be filtered into the lower ash chamber and enter the primary ash silo 2 through the first lower ash pipe 21. The coarser secondary ash cannot pass through the filter plate 63 and accumulates in the upper ash chamber, and is collected through the second lower ash pipe 93 into the secondary ash silo 3.

[0042] The ash collection box 61 is also equipped with a level switch 64 for monitoring the accumulation of secondary fine ash in the upper ash chamber. The level switch 64 is connected to the second pneumatic gate valve 94. When the secondary fine ash accumulates to a certain amount in the upper ash chamber, triggering the level switch 64, the second pneumatic gate valve 94 opens to collect the secondary fine ash. The level switch 64 can be a conventional control switch such as a height-triggered switch or a gravity-triggered switch.

[0043] Through the structural design of the sorting guide 9, the fine ash can be sorted again, so that the primary and secondary fine ash can be directly used in the corresponding production, which greatly reduces the sorting cost and improves the sorting efficiency.

[0044] Example 3

[0045] like Figure 4 As shown, Figure 4 This is a structural view of the sorting machine 5. The sorting machine 5 includes a raw ash inlet pipe 52, a volute 53, a fine ash outlet pipe 54, an inner cylinder 55, a coarse ash outlet pipe 56, and an adjusting baffle 57. The sorting inlet is located on the raw ash inlet pipe 52, the secondary air damper 51 and the coarse ash outlet are located on the coarse ash outlet pipe 56, and the fine ash outlet is located on the fine ash outlet pipe 54. The raw ash inlet pipe 52 is located tangentially to the volute 53, and the coarse ash outlet pipe 56 is located at the lower part of the volute 53. The inner cylinder 55 is concentrically located inside the volute 53. The wall of the inner cylinder 55 has a fine ash inlet and the fine ash outlet pipe 54 along the axial direction. The interior of the volute 53 communicates with the inner cylinder 55 through the fine ash inlet. The adjusting baffle 57 is located between the outer wall of the inner cylinder 55 and the inner wall of the volute 53.

[0046] The adjustment angle of the adjusting baffle 57 is from 0° to 45° (0° to -45°), and the fine ash sieve residue changes from fine to coarse. The secondary air damper 51 is adjusted by the adjusting butterfly valve, and the adjustment angle is from 0° to 90°, and the fine ash sieve residue changes from fine to coarse. The fine ash outlet pipe 54 is provided with a perforated plate, and the diameter of the holes on the perforated plate changes from small to large, and the fine ash sieve residue changes from fine to coarse.

[0047] Example 4

[0048] The multi-stage fly ash sorting method of the present invention employs the multi-stage fly ash sorting system. The multi-stage fly ash sorting method includes a primary fine ash collection stage, a secondary fine ash collection stage, and a cleaning stage. In the secondary fine ash collection stage, the exhaust gas pipeline 85 is closed, the raw ash outlet of the raw ash silo 1 is opened, and material is fed into the first conveying pipeline 81. The ash raw material undergoes coarse and fine ash classification by the separator 5. The classified coarse ash is discharged into the tertiary ash silo 4 for collection, while the fine ash enters the cyclone separator 6 for gas-ash separation. The separated fine ash falls into the ash collection box 61. The second pneumatic gate valve 94 is opened, and the first pneumatic gate valve 22 is closed. The primary fine ash enters the primary ash silo 2 for collection via the first ash discharge pipe 21. The secondary fine ash accumulates in the ash collection box 61. When the accumulation of secondary fine ash in the ash collection box 61 triggers the material level switch 64, the material enters the secondary ash collection stage. In the primary ash collection stage, the raw ash outlet of the primary ash silo 1 is closed and feeding into the first conveying pipe 81 is stopped. The first pneumatic gate valve 22 is opened, and the second pneumatic gate valve 94 is closed. The secondary ash enters the secondary ash silo 3 for collection through the air inclined pipe 91. After the secondary ash collection stage has run for a set time, the cleaning stage begins. The raw ash outlet of the primary ash silo 1 is closed and feeding into the first conveying pipe 81 is stopped. The second pneumatic gate valve 94 is opened, and the first pneumatic gate valve 22 is closed. The exhaust gas pipe 85 is opened to clean the exhaust gas containing trace amounts of dust in the conveying pipe 8. The dust collector installed in the primary ash silo 2 purifies and discharges the exhaust gas to avoid excessive dust in the exhaust gas from adversely affecting the fan 7 or the conveying speed in the conveying pipe 8. After the cleaning stage has run for a set time, the primary ash collection stage begins again.

[0049] The set time for the secondary fine ash collection stage and the cleaning stage is generally determined based on the actual production situation and can be adjusted accordingly based on different production states.

[0050] The multi-stage sorting method for fly ash described in this invention can effectively collect the primary and secondary fine ash separately. The primary and secondary fine ash have relatively high collection purity and can be directly used for subsequent applications, facilitating the full and effective utilization of fly ash.

[0051] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A multi-stage sorting system for fly ash, characterized in that, The system includes a raw ash silo, a primary ash silo, a secondary ash silo, and a tertiary ash silo. The raw ash silo contains ash raw materials. The primary ash silo contains primary fine ash. The secondary ash silo contains secondary fine ash. The tertiary ash silo contains coarse ash. The tertiary ash silo has a separator at its tertiary ash inlet. The primary ash silo has a cyclone separator at its primary ash inlet. The secondary ash silo has a secondary ash inlet connected to the ash collection box at the bottom of the cyclone separator via a separator guide. The raw ash outlet of the raw ash silo, the separator, the cyclone separator, and the blower are connected via a conveying pipeline.

2. The multi-stage fly ash sorting system as described in claim 1, characterized in that, The conveying pipeline includes a first conveying pipeline, a second conveying pipeline, a connecting pipeline, and a return pipeline. The output port of the blower is connected to the sorting inlet of the separator through the first conveying pipeline. The raw ash outlet of the raw ash silo is located on the first conveying pipeline. The output port of the blower is connected to the secondary damper of the separator through the second conveying pipeline. The coarse outlet at the bottom of the separator is connected to the tertiary ash inlet of the tertiary ash silo. The fine outlet of the separator is connected to the separation inlet of the cyclone separator through the connecting pipeline. The gas outlet of the cyclone separator is connected to the blower through the return pipeline, thereby forming a closed-loop conveying pipeline.

3. The multi-stage fly ash sorting system as described in claim 2, characterized in that, The conveying pipeline also includes a waste gas pipeline, the two ends of which are connected to the upper part of the first conveying pipeline and the primary ash silo, respectively. A regulating butterfly valve is installed on the waste gas pipeline to control the opening and closing of the waste gas pipeline.

4. The multi-stage fly ash sorting system as described in claim 3, characterized in that, The sorting guide includes an air inclined trough pipe, the two ends of which are connected to the top of the ash collection box and the top of the secondary ash silo, respectively. The air inclined trough pipe is inclined from the top of the ash collection box to the top of the secondary ash silo from high to low.

5. The multi-stage fly ash sorting system as described in claim 4, characterized in that, A blower is installed on the air inclined duct to provide transport power for the fine ash inside the air inclined duct.

6. The multi-stage fly ash sorting system as described in claim 4, characterized in that, The lower part of the ash collection box is provided with an ash collection section, which is configured as a funnel-shaped structure with a cross-section that gradually decreases from top to bottom. The bottom of the ash collection section is connected to the top of the primary ash silo through a first ash discharge pipe. A second ash discharge pipe is provided on the side of the ash collection section. One end of the second ash discharge pipe is connected to the interior of the ash collection section, and the other end is connected to the upper end of the air inclined trough pipe. The secondary fine ash in the ash collection section enters the air inclined trough pipe through the second ash discharge pipe. A first pneumatic gate valve is provided on the first ash discharge pipe, and a second pneumatic gate valve is provided on the second ash discharge pipe.

7. The multi-stage fly ash sorting system as described in claim 6, characterized in that, The top of the secondary ash silo is equipped with a dust suction pipe, which is U-shaped. One end of the dust suction pipe is connected to the secondary ash silo, and the other end is connected to the lower end of the air inclined trough pipe. The dust suction pipe is also equipped with a sealable inspection and unblocking hole, which is located at the lower end of the air inclined trough pipe.

8. The multi-stage fly ash sorting system as described in claim 6, characterized in that, The ash collection section is equipped with a filter plate, which divides the interior of the ash collection section into an upper ash chamber and a lower ash chamber distributed vertically. The filter plate is provided with filter holes, and the upper ash chamber and the lower ash chamber are connected only through the filter holes. The filter plate is located below the connection between the second lower ash pipe and the ash collection section, and above the first lower ash pipe.

9. The multi-stage fly ash sorting system as described in claim 8, characterized in that, The ash collection box is also equipped with a material level switch to monitor the accumulation of the secondary fine ash in the upper ash chamber. The material level switch is connected to the second pneumatic gate valve.

10. A multi-stage sorting method for fly ash, characterized in that, The multi-stage fly ash sorting system as described in claim 9 includes a primary fine ash collection stage, a secondary fine ash collection stage, and a cleaning stage. In the secondary fine ash collection stage, the exhaust gas pipeline is closed, the raw ash outlet of the raw ash silo is opened and feeds material into the first conveying pipeline. The ash raw material is classified into coarse and fine ash by the sorting machine. The classified coarse ash is discharged into the tertiary ash silo for collection, and the fine ash enters the cyclone separator for gas-ash separation. The separated fine ash falls into the ash collection box. The second pneumatic gate valve is opened, the first pneumatic gate valve is closed, and the primary fine ash enters the primary ash silo for collection through the first ash discharge pipe. The secondary fine ash accumulates in the ash collection box. When the accumulation of secondary fine ash in the ash collection box triggers the material level switch, the secondary fine ash collection stage begins. The raw ash outlet of the raw ash silo is closed and feeding into the first conveying pipe is stopped. The first pneumatic gate valve is opened and the second pneumatic gate valve is closed. The secondary fine ash enters the secondary ash silo for collection through the air inclined pipe. After the secondary fine ash collection stage is completed, the cleaning stage begins. The raw ash outlet of the raw ash silo is closed and feeding into the first conveying pipeline is stopped. The second pneumatic gate valve is opened, the first pneumatic gate valve is closed, and the exhaust gas pipeline is opened. After the cleaning stage is completed, the primary fine ash collection stage begins again.

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