A sludge drying disposal system and disposal method

Abstract

The present application relates to a kind of sludge drying disposal system and disposal method, including first-stage drying device and secondary drying device successively, sludge is mixed into coal mill after drying treatment by secondary drying device, coal mill is ground into coal powder with raw coal and then transported to the hearth of boiler for combustion;The air inlet and air outlet of first-stage drying device are connected to the dry residue machine of boiler by hot air pipe one and cold air pipe one respectively, to form cold and hot air circulation;Air preheater of boiler is connected to the air inlet of secondary drying device by hot air pipe two, and cold air branch pipe two and hot air pipe two connected to the air outlet of secondary drying device are connected to coal mill respectively;Cold air pipe one is connected to coal mill by cold air branch pipe one, so that the cooling requirement of boiler hot residue and the drying requirement of sludge are reliably combined, waste heat is effectively used in the drying of sludge, each takes what is needed, greatly improves energy efficiency, saves energy, and can help to control the exhaust gas temperature of coal mill.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sludge drying treatment, in particular to a sludge drying treatment system and method. BACKGROUND

[0002] The coal-fired power plant burns municipal sludge to become a new income growth point. When the water content of municipal sludge is high, it needs to be dried and treated before being transported into the boiler for burning. In the prior art, sludge is usually dried by steam as a heat source, and the steam energy consumption is large. In the drying process, the sludge can only be passively moved along with the heating surface, the heat transfer efficiency is low, and the drying is uneven and inefficient.

[0003] On the other hand, the dry slag discharge system is used for the coal-fired boiler to discharge hot slag. The cooling source is used to cool the hot slag, and then the cold slag is sent to the slag bin. The cooling source generally uses an independent cold air system.

[0004] In addition, the coal pulverizing system of the coal-fired power plant usually uses a positive pressure direct blowing type coal mill. The outlet temperature of the coal mill has certain interval requirements, generally 50-80℃. The control of the temperature interval is realized by an independent air inlet system. SUMMARY

[0005] To solve the above problems, the present application provides a sludge drying treatment system and method with reasonable structure, so as to realize reliable combination of the cooling requirement of the boiler hot slag and the drying requirement of the sludge, effectively use the waste heat for sludge drying, meet the requirements of each other, greatly improve the energy efficiency, save energy, and help control the exhaust gas temperature of the coal mill.

[0006] The technical scheme adopted by the present application is as follows:

[0007] A sludge drying treatment system comprises a first drying device and a second drying device connected in sequence. The sludge is dried by the second drying device and then mixed into the coal mill. The coal mill grinds the sludge and raw coal into coal powder and then transports the coal powder to the furnace of the boiler for combustion. The air inlet and outlet of the first drying device are connected to the dry slag machine of the boiler through hot air pipe one and cold air pipe one respectively, forming a cold and hot air circulation. The air preheater of the boiler is connected to the air inlet of the second drying device through hot air pipe two. The cold air branch pipe two and hot air pipe two connected to the air outlet of the second drying device are connected to the coal mill respectively. The cold air pipe one is connected to the coal mill through the cold air branch pipe one.

[0008] Further improvement of the above technical scheme:

[0009] The fan one is connected in series on the hot air pipe one and the cold air pipe one respectively, the cold air branch pipe one is communicated on the cold air pipe one between the fan one and the first drying device, the adjusting valve one and the fan two are installed in series on the cold air branch pipe one.

[0010] The adjusting valve three is installed in series on the hot air pipe two, the hot air pipe two between the adjusting valve three and the coal mill is communicated to the air inlet of the second drying device through the hot air branch pipe, and the adjusting valve two is installed in series on the hot air branch pipe.

[0011] The first drying device and the second drying device adopt the spiral feeding structure to convey the sludge.

[0012] The first drying device and the second drying device are the same in structure and each include an inner cylinder and an outer cylinder which are nested at intervals, the spiral pieces are arranged on the outer wall surface of the inner cylinder along the length direction, the sludge is conveyed along the axial direction of the inner cylinder through the spiral pieces with the rotation of the inner cylinder, the end of the inner cylinder is communicated and arranged as the air inlet of the hot air, and a plurality of air outlets are formed on the inner cylinder wall surface.

[0013] The conveying direction of the hot air relative to the axial direction of the inner cylinder is opposite to the conveying direction of the sludge relative to the axial direction of the inner cylinder.

[0014] The outer pipe is arranged at each air outlet, the inner pipe is arranged at the outer end of the outer pipe, the air cap is arranged at the end of the inner pipe, the diameter of the air cap is larger than that of the outer pipe, the air cap shields the end of the outer pipe and the inner pipe, and the through hole is formed on the inner pipe outside the outer end of the outer pipe.

[0015] The axial sliding structure is arranged between the inner pipe and the outer pipe, the elastic body is arranged between the inner pipe and the outer pipe, and the elastic body promotes the inner pipe to retract into the outer pipe.

[0016] The rotation directions of the outer cylinder and the inner cylinder are opposite, the sludge carrying teeth are formed on the inner wall surface of the outer cylinder and extend inward, and the distance exists between the inner edge of the sludge carrying teeth and the outer edge of the spiral piece.

[0017] A disposal method of the sludge drying disposal system includes the following steps.

[0018] The wet sludge with the water content of 55%-65% is conveyed to the first drying device, meanwhile, the hot air of the dry residue machine is transmitted to the first drying device through the hot air pipe one, the hot air is transmitted from the rear end to the front end of the first drying device, the wet sludge is transmitted from the front end to the rear end of the first drying device, and the wet sludge is dried by the hot air, the hot air is cooled and flows out of the first drying device, flows back to the dry residue machine through the cold air pipe one, and the wet sludge after the first drying has the water content of about 35%-45% and is conveyed to the second drying device.

[0019] The hot air of the boiler air preheater is transmitted to the air inlet of the secondary drying device, and the hot air is transmitted to the coal mill through the cold air branch pipe II after being cooled, and the wet sludge is subjected to secondary drying in the secondary drying device, and the water content is dried to 15%-25%;

[0020] The secondary dried sludge is transmitted to the coal mill, ground into coal powder together with raw coal, and then transmitted to the furnace of the boiler for combustion, and the slag after combustion is cooled by the dry slag machine and then sent to the slag bin; meanwhile, the hot air output from the air preheater, the cold air output from the primary drying device, and the cold air output from the secondary drying device are respectively supplied to the coal mill.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The present application has the following advantages:

[0023] The present application also has the following advantages:

[0024] The cold air output from the primary drying device and the secondary drying device, and the hot air output from the air preheater, are respectively transmitted to the coal mill, and the outlet temperature of the coal mill can be adjusted and controlled by adjusting the ratio of the air volume, which effectively helps to control the moisture, temperature and exhaust gas temperature in the coal mill.

[0025] Spiral feeding structures are used in the primary drying device and the secondary drying device, and the sludge is fluidized and dried by the hot air sprayed from the inner cylinder during the spiral conveying process, which ensures uniform drying and effectively guarantees the drying effect. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The figure is a structural schematic diagram of the present application.

[0027] Figure 2 The figure is a layout schematic diagram of the inner cylinder and the spiral piece in the primary drying device of the present application.

[0028] Figure 3 The figure is a structural schematic diagram of the air outlet hole of the inner cylinder.

[0029] Figure 4 The figure is a sectional view of the inner cylinder and the outer cylinder of the primary drying device of the present application.

[0030] The components include: 1. Boiler; 2. Slag dryer; 3. Cold air duct 1; 4. Fan 1; 5. Hot air duct 1; 6. Cold air branch duct 1; 7. Regulating valve 1; 8. Primary drying unit; 9. Fan 2; 10. Coal mill; 11. Cold air branch duct 2; 12. Secondary drying unit; 13. Hot air branch duct; 14. Regulating valve 2; 15. Slag bin; 16. Regulating valve 3; 17. Air preheater; 18. Hot air duct 2.

[0031] 81. Inner cylinder; 82. Spiral blade; 83. Air outlet; 84. Air cap; 85. Inner tube; 86. Outer tube; 87. Outer cylinder; 88. Sludge carrying teeth. Detailed Implementation

[0032] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0033] like Figure 1 As shown, a sludge drying and disposal system in this embodiment includes a primary drying device 8 and a secondary drying device 12 connected front and rear. After being dried by the secondary drying device 12, the sludge is mixed into a coal mill 10. The coal mill 10 grinds the sludge and raw coal together into pulverized coal, which is then transported to the furnace of the boiler 1 for combustion. The air inlet and outlet of the primary drying device 8 are connected to the slag dryer 2 of the boiler 1 via hot air pipe 5 and cold air pipe 3, respectively, forming a hot and cold air circulation. The air preheater 17 of the boiler 1 is connected to the air inlet of the secondary drying device 12 via hot air pipe 2 18. The cold air branch pipe 2 11 and hot air pipe 2 18, which are connected to the air outlet of the secondary drying device 12, are respectively connected to the coal mill 10. The cold air pipe 3 is connected to the coal mill 10 via cold air branch pipe 6.

[0034] In this embodiment, the cooling requirements of the hot slag from boiler 1 and the drying requirements of sludge are reliably combined, and the waste heat is effectively used in the drying of sludge, so that each takes what it needs; the slag dryer 2, air preheater 17, coal mill 10 and sludge drying are formed into a unified and coordinated system, so as to achieve the rational use of heat, simplify the equipment and save external energy.

[0035] In this embodiment, the cold air output from the primary drying device 8 and the secondary drying device 12, and the hot air output from the air preheater 17 are respectively delivered to the coal mill 10. The outlet temperature of the coal mill 10 can be adjusted and controlled by adjusting the air volume ratio, which effectively helps to control the moisture, temperature and flue gas temperature in the coal mill 10.

[0036] Fan 4 is connected in series on hot air duct 5 and cold air duct 3 respectively. The installation of fan 4 helps to ensure the smooth circulation of hot and cold air. Cold air branch duct 6 is connected to cold air duct 3 between fan 4 and primary drying device 8. Regulating valve 7 and fan 9 are installed in series on cold air branch duct 6, so that the air volume delivered on cold air branch duct 6 is regulated and determined by fan 9 and regulating valve 7.

[0037] A regulating valve 16 is connected in series on the hot air duct 18. The hot air duct 18, located between the regulating valve 16 and the coal mill 10, is connected to the air inlet of the secondary drying unit 12 via the hot air branch pipe 13. A regulating valve 14 is connected in series on the hot air branch pipe 13. Thus, the regulating valve 16 regulates the total air volume on the hot air duct 18, and the regulating valve 14 controls the air volume of hot air supplied to the secondary drying unit 12 via the hot air branch pipe 13. The combined effect of the regulating valves 16 and 14 controls the air volume of hot air supplied to the coal mill 10 via the hot air duct 18.

[0038] Both the primary drying unit 8 and the secondary drying unit 12 adopt a screw feeding structure to transport the sludge. This screw feeding allows for the transport and tumbling of the sludge during hot air drying, ensuring the uniformity of sludge drying.

[0039] The primary drying unit 8 and the secondary drying unit 12 have the same structure, both including an inner cylinder 81 and an outer cylinder 87 nested together with interlocking layers, such as... Figure 2 As shown, a spiral blade 82 is wound along the length direction on the outer wall of the inner cylinder 81. As the inner cylinder 81 rotates, the sludge is transported along the axial direction of the inner cylinder 81 through the spiral blade 82. The end of the inner cylinder 81 is connected to a hot air inlet, and multiple air outlet holes 83 that are open through the inside and outside are provided on the wall of the inner cylinder 81.

[0040] In this embodiment, both the primary drying device 8 and the secondary drying device 12 adopt a spiral feeding structure. During the spiral conveying process, the sludge is fluidized and dried by hot air sprayed out from the inner cylinder 81, ensuring the uniformity of drying and effectively guaranteeing the drying effect.

[0041] The hot air is conveyed in the opposite direction to the axial direction of the inner cylinder 81, which effectively ensures the drying efficiency and effect of the sludge output from the primary drying device 8.

[0042] like Figure 3 As shown, each air outlet 83 is equipped with an outer tube 86, an inner tube 85 is equipped at the outer end of the outer tube 86, and a wind cap 84 is equipped at the end of the inner tube 85. The diameter of the wind cap 84 is larger than that of the outer tube 86, and the wind cap 84 blocks the ends of the outer tube 86 and the inner tube 85. A through hole is opened on the inner tube 85 located outside the end of the outer tube 86.

[0043] In this embodiment, an outer pipe 86, an inner pipe 85, and a wind cap 84 are provided at the air outlet 83, which effectively avoids direct contact between the transported sludge and the air outlet 83, and especially prevents sludge from falling into the air outlet 83 and causing blockage.

[0044] The inner tube 85 and the outer tube 86 are provided with an axial sliding structure, and an elastic body is jointly installed between the inner tube 85 and the outer tube 86, and the elastic body promotes the retraction of the inner tube 85 into the outer tube 86.

[0045] In the embodiment, the relative axial sliding between the inner tube 85 and the outer tube 86 can be passively controlled by the hot air pressure or actively controlled by a linear power mechanism. Through the axial sliding between the inner tube 85 and the outer tube 86, the size and the air volume of the actual air outlet on the wall surface of the inner cylinder 81 are adjusted, the influence of the sludge on the air outlet 83 is reduced or even avoided, and the hot air volume can be matched with the sludge conveying to effectively coordinate and be consistent with the sludge conveying.

[0046] As shown in Figure 4 The outer cylinder 87 and the inner cylinder 81 rotate in opposite directions, the inner wall surface of the outer cylinder 87 extends inward to form a plurality of sludge carrying teeth 88, and there is a distance between the inner edge of the sludge carrying teeth 88 and the outer edge of the spiral blade 82.

[0047] In the embodiment, the outer cylinder 87 and the inner cylinder 81 rotate in opposite directions, and the sludge carrying teeth 88 on the inner wall surface of the outer cylinder 87 are provided to effectively assist the overturning and uniformity of the sludge during the conveying process, improve and guarantee the drying effect.

[0048] In the embodiment, the heat in the boiler 1 and the air preheater 17 is reasonably utilized to dry the sludge, which replaces the original steam drying of the sludge, effectively saves energy, and simplifies the investment of independent equipment.

[0049] In the embodiment, the cold air output from the first drying device 8 and the second drying device 12 and the hot air output from the air preheater 17 are respectively conveyed to the coal mill 10, and the air volume and the air temperature in the coal mill 10 are adjusted by adjusting the adjusting valve one 7 on the cold air branch pipe one 6, the adjusting valve three 16 on the hot air pipe two 18, and the adjusting valve two 14 on the hot air branch pipe 13, wherein the adjustment of the adjusting valve one 7 on the cold air branch pipe one 6 is mainly used.

[0050] The disposal method of the sludge drying disposal system in the embodiment includes the following steps:

[0051] Step one: wet sludge with a water content of 55%-65% is conveyed into the first drying device 8, at the same time, the hot air of the dry slag machine 2 is transmitted to the first drying device 8 through the hot air pipe one 5, the hot air is transmitted from the rear end to the front end of the first drying device 8, the wet sludge is transmitted from the front end to the rear end of the first drying device 8, and the wet sludge is dried by the hot air; the cooled hot air flows out of the first drying device 8 and flows back to the dry slag machine 2 through the cold air pipe one 3, and the wet sludge after the first drying has a water content of about 35%-45% and is conveyed to the second drying device 12;

[0052] In this embodiment, a cooling air is introduced at the dry slag machine 2 of the boiler 1 to cool the hot slag in the dry slag machine 2, so as to ensure that the slag temperature meets the conveying requirement of the dry slag machine; meanwhile, the cooling air heated by the hot slag is sent into the first-stage drying device 8 to heat and dry the sludge with high water content, and the cooling air after heat release can be sent back to the dry slag machine 2, so that the hot air and the cold air are used as required, and the circulation is realized.

[0053] In step two, the hot air of the air preheater 17 of the boiler 1 is transmitted to the air inlet of the second-stage drying device 12, the hot air is cooled and then transmitted to the coal mill 10 through the cold air branch pipe two 11, and the wet sludge is dried in the second-stage drying device 12 to have a water content of 15%-25%.

[0054] In step three, the sludge dried in the second stage is transmitted to the coal mill 10, ground into coal powder together with the raw coal, and then transmitted to the furnace of the boiler 1 to be combusted, the slag after combustion is cooled by the dry slag machine 2 and then sent to the slag bin 15; meanwhile, the hot air output from the air preheater 17, the cold air output from the first-stage drying device 8, and the cold air output from the second-stage drying device 12 are respectively supplied to the coal mill 10.

[0055] The present application reliably combines the cooling requirement of the boiler slag and the drying requirement of the sludge, effectively uses the waste heat for drying the sludge, uses the hot air and the cold air as required, greatly improves the energy efficiency, saves energy, and can help control the exhaust gas temperature of the coal mill.

[0056] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0057] The above description is an explanation of the present application, not a limitation of the application, the scope of the present application is defined in the claims, and any modification within the protection scope of the present application can be made.

Claims

1. A sludge dewatering disposal system characterized by: The application relates to a sludge drying device, which comprises a primary drying device (8) and a secondary drying device (12) connected in sequence, wherein sludge is mixed into a coal mill (10) after being dried by the secondary drying device (12), the coal mill (10) grinds the sludge and raw coal into coal powder, and the coal powder is delivered to a furnace of a boiler (1) for combustion; the air inlet and air outlet of the primary drying device (8) are connected to the dry residue machine (2) of the boiler (1) through a hot air pipe I (5) and a cold air pipe I (3) respectively, thereby forming a cold and hot air circulation; an air preheater (17) of the boiler (1) is connected to the air inlet of the secondary drying device (12) through a hot air pipe II (18), a cold air branch pipe II (11) and the hot air pipe II (18) connected to the air outlet of the secondary drying device (12) are connected to the coal mill (10) respectively; the cold air pipe I (3) is connected to the coal mill (10) through a cold air branch pipe I (6). The primary drying device (8) and the secondary drying device (12) have the same structure and comprise an inner cylinder (81) and an outer cylinder (87) which are nested at intervals, the outer wall surface of the inner cylinder (81) is provided with spiral blades (82) along the length direction, sludge is delivered along the axial direction of the inner cylinder (81) through the spiral blades (82) during the rotation of the inner cylinder (81), the end of the inner cylinder (81) is connected and provided as the air inlet of hot air, and a plurality of air outlets (83) penetrating through the inner and outer cylinders are formed in the wall surface of the inner cylinder (81). An outer pipe (86) is arranged at each air outlet (83), an inner pipe (85) is arranged at the outer end of the outer pipe (86), a cap (84) is arranged at the end of the inner pipe (85), the diameter of the cap (84) is larger than that of the outer pipe (86), and the cap (84) shields the end of the outer pipe (86) and the inner pipe (85); a through hole penetrating through the inner and outer pipes is formed in the inner pipe (85) outside the end of the outer pipe (86). The rotation directions of the outer cylinder (87) and the inner cylinder (81) are opposite, a plurality of sludge carrying teeth (88) are formed in the inner wall surface of the outer cylinder (87) and extend inward, and there is a distance between the inner edge of the sludge carrying teeth (88) and the outer edge of the spiral blades (82) in the diameter direction.

2. A sludge dewatering disposal system as claimed in claim 1, characterized in that: A fan I (4) is connected in series on the hot air pipe I (5) and the cold air pipe I (3) respectively, and the cold air branch pipe I (6) is connected on the cold air pipe I (3) between the fan I (4) and the primary drying device (8); an adjusting valve I (7) and a fan II (9) are installed in series on the cold air branch pipe I (6).

3. A sludge dewatering disposal system as claimed in claim 1, wherein: An adjusting valve III (16) is installed in series on the hot air pipe II (18), the hot air pipe II (18) between the adjusting valve III (16) and the coal mill (10) is connected to the air inlet of the secondary drying device (12) through a hot air branch pipe (13), and an adjusting valve II (14) is installed in series on the hot air branch pipe (13).

4. A sludge dewatering disposal system as claimed in claim 1, wherein: The primary drying device (8) and the secondary drying device (12) both adopt a spiral feeding structure to deliver sludge.

5. A sludge dewatering disposal system as claimed in claim 1, wherein: The delivery direction of the hot air relative to the axial direction of the inner cylinder (81) is opposite to the delivery direction of the sludge relative to the axial direction of the inner cylinder (81).

6. A sludge dewatering disposal system as claimed in claim 1, wherein: The inner tube (85) and the outer tube (86) are provided with an axial sliding structure, and the inner tube (85) and the outer tube (86) are jointly provided with an elastic body, and the elastic body promotes the inner tube (85) to retract into the outer tube (86).

7. A method of disposal of the sludge dewatering disposal system according to claim 1, characterized by: The method comprises the following steps: The wet sludge with a moisture content of 55%-65% is transported into the first-stage drying device (8), and the hot air of the dry slag machine (2) is transferred to the first-stage drying device (8) through the hot air pipe I (5), the hot air is transferred from the rear end to the front end of the first-stage drying device (8), the wet sludge is transferred from the front end to the rear end of the first-stage drying device (8), and the wet sludge is dried by the hot air; the cooled hot air flows out of the first-stage drying device (8), flows back to the dry slag machine (2) through the cold air pipe I (3), the wet sludge after the first-stage drying has a moisture content of 35%-45% and is transported into the second-stage drying device (12); The hot air of the air preheater (17) of the boiler (1) is transferred to the air inlet of the second-stage drying device (12), the cooled hot air is transported into the coal mill (10) through the cold air branch pipe II (11), the wet sludge is subjected to the second-stage drying in the second-stage drying device (12), and the moisture content is dried to 15%-25%; The sludge after the second-stage drying is transported into the coal mill (10), is ground into coal powder together with raw coal, and is transported into the furnace of the boiler (1) to be combusted, the slag after the combustion is cooled by the dry slag machine (2) and is sent into the slag bin (15); meanwhile, the hot air output from the air preheater (17), the cold air output from the first-stage drying device (8), and the cold air output from the second-stage drying device (12) are respectively supplied into the coal mill (10).

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