A sludge dewatering system and method

Abstract

The present application aims at the problems that the existing sludge drying technology is not designed according to different drying stages, resulting in low thermal efficiency, and the odor is independently treated, resulting in high energy consumption, and discloses a sludge drying system and method. The system comprises a biomass gasification furnace, an adiabatic combustion chamber, a waste heat boiler and high and low speed sludge drying equipment. The high and low speed drying equipment are connected in series through a spiral conveying connecting section, and the flue gas and the sludge are countercurrently heat exchanged. By reducing the speed in the speed-reducing drying section, the sludge residence time is prolonged, the effective diffusion coefficient of the sludge internal moisture is improved, and the thermal efficiency is improved. At the same time, the odor is classified and treated, the high-concentration odor is treated by a special pipe, and the low-concentration environmental odor is introduced into the adiabatic combustion chamber for high-temperature oxidation and decomposition. The present application improves the overall energy cascade utilization rate of the system, and reduces the comprehensive deodorization investment and operation cost.

Description

Technical Field

[0001] This invention relates to the field of sludge treatment and resource utilization technology, specifically to a sludge drying system and method. Background Technology

[0002] Industrial parks typically face simultaneous demands for industrial steam and the drying of sludge produced by wastewater treatment plants. However, existing rotary sludge heating and drying solutions often employ a single drying shaft and cylinder, failing to incorporate segmented structural design based on the changing moisture content of the sludge during the drying process. The mass transfer kinetics of sludge differ between the constant-speed and falling-speed drying sections; a single rotation speed and heat supply method restricts moisture diffusion within the falling-speed drying section, resulting in low drying thermal efficiency.

[0003] Meanwhile, the flue gas temperature after biomass gasification and combustion is relatively high, and the high-concentration thermal drying waste gas and low-concentration environmental odor gas generated in the park usually require separate two- or multi-stage treatment equipment, which makes the investment and operating costs of the waste gas treatment system high and the overall energy cascade utilization rate of the system insufficient.

[0004] Therefore, how to provide a sludge drying system and method has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a sludge drying system and method to solve the technical problems in the prior art where the sludge drying system does not have a segmented structural design for different drying stages, resulting in low dewatering efficiency, and the flue gas waste heat and exhaust gas are not systematically and synergistically treated.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a sludge drying system, comprising a biomass gasifier, an adiabatic combustion chamber, a waste heat boiler, a high-speed sludge drying device, a low-speed sludge drying device, and a connecting section; the gas outlet of the biomass gasifier is connected to the air inlet of the adiabatic combustion chamber; the exhaust outlet of the adiabatic combustion chamber is connected to the air inlet of the waste heat boiler and the air inlet of the low-speed sludge drying device, respectively; the gas outlet of the low-speed sludge drying device is connected to the air inlet of the high-speed sludge drying device; the discharge outlet of the high-speed sludge drying device is connected to the feed inlet of the connecting section, and the discharge outlet of the connecting section is connected to the feed inlet of the low-speed sludge drying device.

[0007] It is evident that by independently setting up high-speed and low-speed sludge drying equipment on physical devices, and arranging the flue gas flow direction in the opposite direction to the sludge displacement direction, thermodynamic and kinetic segmented matching of the constant-rate drying section and the falling-rate drying section is achieved. This provides long-term heat transfer during the falling-rate drying period and rapid transport during the constant-rate drying period, improving the overall system's dehydration thermal efficiency and also catering to industrial heating needs within the park.

[0008] Furthermore, the connecting section includes a screw conveyor and a sealing device; the feed end of the screw conveyor is connected to the discharge port of the high-speed sludge drying equipment, and the discharge end of the screw conveyor passes through the sealing device and is connected to the feed port of the low-speed sludge drying equipment.

[0009] It is evident that by utilizing the combination of screw conveyors and sealing facilities, the continuity of material transport between high-speed and low-speed equipment is maintained, and gas crosstalk between the internal environment of the drying system and the outside environment is effectively blocked, preventing the leakage of heat and odor.

[0010] Furthermore, it also includes exhaust gas purification facilities; the exhaust port of the waste heat boiler is connected to the air inlet of the exhaust gas purification facilities, and the exhaust end of the exhaust gas purification facilities is equipped with a reuse pipeline that connects to the interior of the high-speed sludge drying equipment.

[0011] It is evident that by recirculating a portion of the purified exhaust gas into the later stages of the high-speed sludge drying equipment, a secondary heat source is provided for the sludge drying equipment, increasing the total heat and improving the airflow linear velocity, thereby increasing the heat transfer coefficient and reducing boiler flue gas heat loss.

[0012] Furthermore, it also includes a sealing cover, a combustion-supporting fan, and an emergency deodorization device; the exhaust port of the sealing cover is connected to the air inlet of the combustion-supporting fan, and the exhaust port of the combustion-supporting fan is connected to the air inlet of the insulated combustion chamber; the exhaust pipe of the sealing cover is connected to the air inlet of the emergency deodorization device through a bypass branch pipe; a regulating valve is installed on the inlet air pipe of the combustion-supporting fan.

[0013] It is evident that by using a combustion-supporting fan to directly inject low-concentration odorous gas into the insulated combustion chamber for high-temperature pyrolysis, the original combustion system is used to remove malodorous gases during the sludge drying process, reducing the investment in independent deodorization equipment. The emergency deodorization device ensures that environmental emissions meet standards when the combustion system is shut down for maintenance. The regulating valve can flexibly adjust the mixing ratio of fresh air and low-concentration odorous gas to ensure that the insulated combustion chamber has sufficient combustion-supporting airflow.

[0014] Furthermore, it also includes a high-concentration odor treatment device and a sludge silo; the exhaust ports of the high-speed sludge drying equipment and the sludge silo are both connected to the air inlet of the high-concentration odor treatment device; the high-concentration odor treatment device is sequentially connected to a washing device, a demisting device, an adsorption purification device, and a second exhaust stack along the gas flow direction; the exhaust gas purification facility is sequentially connected to a denitrification device, a waste heat recovery device, a desulfurization device, and a dust removal device along the gas flow direction, and its exhaust port is connected to the first exhaust stack.

[0015] It is evident that by centrally collecting and utilizing the series flow treatment of multi-stage physical, chemical washing and adsorption purification units, the high concentration of odorous substances generated during drying is deeply purified and removed; at the same time, by utilizing the cooperation of denitrification, desulfurization and dust removal devices, the various pollutants in the flue gas at the tail end of the waste heat boiler are deeply purified and the waste heat is fully recovered, ensuring that the exhaust gas meets the emission standards.

[0016] A sludge drying method, applied to the aforementioned sludge drying system, includes the following steps: feeding the sludge to be treated into a high-speed sludge drying device for constant-rate drying; feeding the sludge treated by the high-speed sludge drying device into a low-speed sludge drying device through a connecting section for deceleration drying; combustible gas generated by a biomass gasification furnace entering an adiabatic combustion chamber for combustion; high-temperature flue gas generated in the adiabatic combustion chamber being diverted, with the first part entering a waste heat boiler and the second part entering the low-speed sludge drying device; and medium-temperature flue gas discharged from the low-speed sludge drying device being introduced into the high-speed sludge drying device, so that the overall flow direction of the flue gas is counter-current to the sludge conveying direction.

[0017] It is evident that the variable-speed drying control based on the diffusion time matching under different moisture contents of sludge drying, through countercurrent arrangement and segmented control of process steps, enables sludge dewatering and heat source to correspond in stages, thus following the physical laws of deep moisture migration in sludge in terms of process steps.

[0018] Furthermore, segmented control is implemented based on the sludge drying kinetics boundary point: the sludge moisture content entering the high-speed sludge drying equipment is controlled within the range of 60%-40%; the sludge moisture content entering the low-speed sludge drying equipment is controlled within the range of 40%-30%.

[0019] It is evident that by precisely controlling the 40% drying kinetic boundary point, the sludge is physically and spatially isolated and dried in the constant-rate stage where it loses surface free water and in the decelerating stage where deep water migrates, thus maximizing the mass transfer advantages of equipment with different rotation speeds.

[0020] Furthermore, the rotational speed of the cylinder in the low-speed sludge drying equipment is controlled to be 0.7 to 0.8 times that of the cylinder in the high-speed sludge drying equipment, thereby relatively extending the residence time of the sludge within the low-speed sludge drying equipment. .

[0021] It is evident that reducing the rotational speed of the deceleration drying section extends the sludge residence time, thereby increasing the sludge particle temperature and consequently increasing the effective moisture diffusion coefficient, thus accelerating internal moisture removal. Simultaneously, reducing the rotational speed in the low-speed section also reduces the dust generated during sludge tumbling, further lowering the operating load on subsequent dust collectors. Maintaining a high rotational speed in the high-speed section ensures rapid tumbling and conveying of the wet sludge.

[0022] Furthermore, the temperature of the flue gas introduced into the low-speed sludge drying equipment is controlled to be... .

[0023] It is evident that by controlling the initial heat source temperature entering the low-speed section, the high-temperature heat transfer temperature difference required for the sludge deceleration drying section is ensured, while excessive pyrolysis and carbonization of sludge organic matter caused by excessively high temperatures are avoided, thus ensuring the safety of the drying process and the cascade utilization of thermal energy.

[0024] Furthermore, the sludge drying system also includes a high-concentration odor treatment device, a combustion fan, a tail gas purification facility, and a first exhaust stack; the exhaust gas discharged from the high-speed sludge drying equipment is collected as high-concentration odor gas and fed into the high-concentration odor treatment device for purification; the overflow exhaust gas around the drying system is collected as low-concentration odor gas and sent into the insulated combustion chamber by the combustion fan for high-temperature oxidation reaction; the flue gas after high-temperature oxidation reaction enters the waste heat boiler with the first part of high-temperature flue gas, and after heat exchange, it is purified by the tail gas purification facility and waste heat is recovered, and finally discharged into the first exhaust stack.

[0025] It is evident that the separate treatment of high and low concentration odor gases makes full use of the existing high-temperature area of ​​the system as a reaction bed for low-concentration waste gas, and, combined with the subsequent complete exhaust gas purification components, reduces the overall odor treatment load of the system. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0027] Figure 1 This is a schematic diagram of a sludge drying process system that uses biomass gasification for heating coupling.

[0028] Figure 2 A schematic diagram of the sludge odor classification process.

[0029] Figure 3 This is a schematic diagram of a high-concentration odor treatment process.

[0030] Figure 4 This is a schematic diagram of the process for treating low-concentration odorous gases.

[0031] Figure 5 This is a schematic diagram of a segmented variable speed sludge drying equipment.

[0032] Explanation of reference numerals in the attached drawings: 1. Biomass gasification furnace; 2. Insulated combustion chamber; 3. Waste heat boiler; 4. High-speed sludge drying equipment; 5. Low-speed sludge drying equipment; 6. Screw conveyor; 7. High-concentration odor treatment device; 8. First regulating valve; 9. Combustion fan; 10. Second regulating valve; 11. Third regulating valve; 12. Emergency deodorization device; 13. Tail gas purification facility; 14. SNCR denitrification device; 15. SCR denitrification device; 16. High-temperature economizer; 17. Semi-dry desulfurization device; 18. Bag filter; 19. Low-temperature economizer; 20. First exhaust stack; 21. Blower; 22. Gas booster fan; 23. Primary spray tower; 24. Secondary spray tower; 25. Alkali washing device; 26. Electrostatic filter; 27. Dewatering and demister; 28. Integrated ultraviolet photocatalytic activated carbon machine; 29. ​​Second exhaust stack. Detailed Implementation

[0033] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0034] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0035] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0036] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0038] (I) System Structure Composition like Figures 1 to 5 As shown, the present invention provides a sludge drying system, which is divided into a heating unit, a drying unit and a waste gas treatment unit in terms of overall physical architecture.

[0039] Regarding the layout of the heating and drying units: The heating unit mainly includes a biomass gasifier 1, an adiabatic combustion chamber 2, and a waste heat boiler 3. Specifically, the gasifier 1 is equipped with a blower 21 at its air inlet. The biomass gasifier 1 utilizes biomass raw materials for pyrolysis and gasification, producing biomass gas, tar, wood vinegar, and biochar, among which the biochar can be sold as a byproduct to increase the system's economic benefits. The gas outlet of the biomass gasifier 1 is connected to the interior of the adiabatic combustion chamber 2 via a gas booster blower 22. Two pipes flow out from the exhaust side of the adiabatic combustion chamber 2. The first pipe connects to the air inlet of the waste heat boiler 3 (which has a structure with a radiant cooling chamber and a convective heat exchange surface, producing qualified steam to supply the park); the second pipe connects to the air inlet of the low-speed sludge drying equipment 5 in the drying unit.

[0040] The drying unit primarily divides the traditional rotary dryer into a high-speed sludge drying unit 4, a connecting section, and a low-speed sludge drying unit 5. The discharge port of the high-speed sludge drying unit 4 is connected to the inlet of the connecting section. The discharge port of the connecting section (which includes a screw conveyor 6 and a sealing device for isolation) is further connected to the inlet of the low-speed sludge drying unit 5, thus achieving closed-loop sludge transfer. In terms of gas flow, the gas outlet of the low-speed sludge drying unit 5 is reversed and connected to the air inlet of the high-speed sludge drying unit 4. Figure 1 In addition, the outlet of the waste heat boiler 3 is connected to the tail gas purification facility 13. Specifically, in this embodiment, the tail gas purification facility 13 includes, in sequence along the flue gas flow direction, an SNCR denitrification device 14, an SCR denitrification device 15, a high-temperature economizer 16 as a waste heat recovery device, a semi-dry desulfurization device 17, a bag filter 18 as a dust removal device, and a low-temperature economizer 19. The exhaust port of the low-temperature economizer 19 is connected to the first exhaust stack 20. A reuse pipe is led out from the exhaust end of the tail gas purification facility 13 and connected to the middle and rear section of the high-speed sludge drying equipment 4.

[0041] like Figures 1 to 4 As shown, regarding the layout of the exhaust gas treatment unit: The system is equipped with a classified treatment pipeline network based on the concentration of the exhaust gas at the source. For high-concentration odorous gases, the exhaust ports of the high-speed sludge drying equipment 4, the sludge silo, and the screw conveyor 6 are all connected and converged into the high-concentration odor treatment device 7. A first regulating valve 8 is installed on the inlet main pipeline. Specifically, the high-concentration odor treatment device 7 is connected in sequence along the gas flow direction to a primary spray tower 23, a secondary spray tower 24, and an alkaline washing device 25, which serve as washing devices; an electrostatic filter 26 and a water demisting and demister 27, which serve as demisting devices; an integrated ultraviolet photolysis activated carbon machine 28, which serves as an adsorption and purification device; and a second exhaust stack 29, which ultimately achieves compliant emissions.

[0042] For low-concentration odors, the exhaust ports of the sealed hood (covering the perimeter of the drying system) and the unloading area are connected to the inlet of the combustion fan 9, and the outlet of the combustion fan 9 is directly connected to the insulated combustion chamber 2. A second regulating valve 10 for introducing fresh air is installed on the inlet air duct of the combustion fan 9, and a third regulating valve 11 is installed on the duct between the sealed hood and the fan inlet. Simultaneously, the exhaust pipe of the sealed hood is also connected to the emergency deodorization device 12 via a bypass branch pipe for switching during system shutdown.

[0043] (II) Drying methods and operating mechanisms Based on the above system structure, this invention proposes a corresponding sludge drying method, the operation and control mechanism of which is as follows: Sludge drying control based on kinetic boundaries: Based on the mechanism analysis of sludge dewatering, a wet basis moisture content of 40% is generally used as the dividing point for drying kinetics. The region with a moisture content above 40% is the constant-rate drying stage, where the main loss is surface free water, resulting in high drying thermal efficiency. The region with a moisture content below 40% is the falling-rate drying stage, where free water is exhausted, and moisture migrates to the surface via internal diffusion. The sludge temperature rises, and the drying rate is controlled by internal mass transfer, resulting in low drying thermal efficiency. According to Fick's second law (Formula 1): Where C is the moisture concentration, t is the time, D is the effective diffusion coefficient, and x is the diffusion direction coordinate.

[0044] For sludge particles, the analytical solution gives the characteristic time required for water removal. (Formula 2): Where r represents the characteristic radius of the sludge, which is determined by the sludge's physical properties and the upstream forming process, and is independent of the cylinder rotation speed. D represents the effective diffusion coefficient. According to the Arrhenius equation, for the effective diffusion coefficient D of the sludge, we have (Equation 3): in, Represents the preceding factor (constant). Indicates the diffusion activation energy ( R represents the universal gas constant. T represents the sludge temperature. Therefore, the higher the sludge temperature, the greater the effective diffusion coefficient, and the better the dewatering effect.

[0045] The sludge temperature T can be calculated using the following formula (Formula 4): in, Indicates the flue gas temperature. The temperature of the sludge entering the falling-rate drying section is indicated by h, which represents the heat transfer coefficient between the sludge and the flue gas. Indicates sludge density, Let A represent the specific heat capacity of the sludge, V represent the surface area of ​​the sludge particles, and t represent the volume of the sludge particles. Except for the residence time, all other parameters are considered constants. Therefore, the longer the residence time, the higher the sludge temperature.

[0046] Based on the above mechanism, the system controls the high-speed and low-speed drying equipment separately. Sludge with high moisture content first enters the high-speed sludge drying equipment 4 (corresponding to a moisture content range of 60%-40%) for rapid tumbling and constant-speed drying; then it enters the low-speed sludge drying equipment 5 (corresponding to a moisture content range of 40%-30%) through the connecting section for decelerated drying.

[0047] In terms of process control, the adiabatic combustion chamber 2 generates high-temperature flue gas at 550℃ to 650℃ (preferably controlled at 600℃), which is then introduced into the low-speed sludge drying equipment 5. The cooled, medium-temperature flue gas is discharged into the high-speed sludge drying equipment 4, so that the overall flow direction of the flue gas is counter-current to the sludge conveying direction, achieving cascade heat exchange. At the same time, the rotation speed of the low-speed sludge drying equipment 5 is controlled to be 0.7 to 0.8 times that of the high-speed section, so that the residence time of sludge in the low-speed section is relatively extended by 25% to 35%. According to the aforementioned formulas (1~4), this measure can effectively increase the temperature of sludge particles in the low-speed section, thereby increasing the effective diffusion coefficient and improving the deep dewatering efficiency.

[0048] In addition, the exhaust gas recycling pipeline sends part of the purified flue gas to the middle and rear section of the high-speed sludge drying equipment 4, which on the one hand supplements the total heat, and on the other hand increases the flue gas flow rate and improves the surface heat transfer coefficient.

[0049] Odor classification and treatment mechanism: In terms of waste gas control methods, after the high-concentration odor gas is converged by the first regulating valve 8, it is subjected to deep purification by physical washing and photodesorption by the high-concentration odor gas treatment device.

[0050] For large volumes of low-concentration odorous gases leaking into the environment, they are sent to the adiabatic combustion chamber 2 by the combustion-supporting fan 9, where free radical chain reactions occur in a high-temperature zone above 800℃. The pyrolysis reaction equations and characteristics of the main odor pollutants are as follows: hydrogen sulfide ( ): (Complete reaction time < 0.5s) The high-temperature flue gas generated after high-temperature combustion enters the waste heat boiler 3. The secondary pollutants (such as NO and SO2) in it are completely absorbed and captured by SNCR+SCR denitrification, semi-dry desulfurization and bag filter in the tail gas purification facility 13, achieving full compatibility with the existing flue gas purification facilities.

[0051] (III) Comparison of Specific Implementation Examples Example 1: Economic Verification of Waste Gas Classification and Treatment This embodiment is equipped with a biomass gasification furnace 1 and a waste heat boiler 3 to co-process sludge.

[0052] The air volume calculation is as follows: The design air volume of the sludge silo is... The sealed cover is designed to have an airflow of [missing information]. The air volume of the screw conveyor is The design air volume of the unloading hall is [missing information]. Approximately ; total After adopting this classification and treatment scheme, high-concentration odor ( ) enters the high-concentration odor treatment device, low-concentration odor ( It enters the adiabatic combustion chamber 2 for combustion.

[0053] Economic comparison results: The traditional solution (one set of sludge thermal drying and purification system + one set of two-stage high-volume deodorization system) requires an investment of approximately 1.5 million yuan and an operating cost of approximately 500,000 yuan per year for the deodorization system. After adopting the technical solution of this invention, the investment in the deodorization system is reduced to 1 million yuan, the operating cost is reduced to 400,000 yuan per year, and all environmental protection indicators meet emission standards. The overall odor control load of the system is significantly reduced.

[0054] Example 2: Verification of the efficiency of segmented variable speed drying Based on Example 1, the calorific value of biomass gas is considered to be 1000 kcal / kg. After adopting segmented speed regulation of the sludge drying equipment, the high-speed section of sludge drying is as follows: Considering that the sludge filling rate is 10% at this time, the low-speed sludge drying stage is respectively carried out according to... , , And 3.0 r / min for observation.

[0055] The sludge temperature T is calculated using Formula 4. According to Formula 4, except for the residence time, all other parameters are constants. A longer residence time results in a higher sludge temperature, a lower flue gas temperature, and a lower final sludge moisture content. However, the sludge temperature cannot be increased indefinitely; the temperature of the sludge drying exhaust gas must be greater than 100℃, otherwise it will lead to low-temperature corrosion at the end of the sludge drying equipment and subsequent flue gas purification facilities. Specific data is shown in the table below. When the rotation speed of the low-speed section of sludge drying is below 3 r / min, the flue gas temperature is below 100℃, which does not meet the flue gas temperature control requirements. Therefore, controlling the rotation speed of the low-speed section of sludge drying to 0.7 to 0.8 times that of the high-speed section is economically reasonable.

[0056] The above data shows that, through the segmented speed-regulating scheme of the sludge drying equipment proposed in this application, the final moisture content of the sludge can be reduced while maintaining the same input heat, significantly improving the thermal efficiency of sludge drying. Based on a daily processing capacity of 100 t / d of sludge with a 60% moisture content, an additional 2.35 t of sludge can be dewatered daily. Assuming a biomass gas consumption of 900 cubic meters per ton of dewatered sludge (at a cost of 0.3 yuan / t), this translates to a daily cost saving of 634.5 yuan. Considering 300 operating days per year, this translates to an annual cost saving of 190,000 yuan. Compared to traditional sludge thermal drying equipment, the dual-stage variable speed sludge drying equipment used in this project is expected to increase investment by 500,000 yuan. The project investment is expected to be recovered within 2.7 years.

[0057] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A sludge drying system, characterized in that, It includes a biomass gasifier, an insulated combustion chamber, a waste heat boiler, a high-speed sludge drying equipment, a low-speed sludge drying equipment, and a connecting section; The gas outlet of the biomass gasifier is connected to the air inlet of the adiabatic combustion chamber. The exhaust port of the insulated combustion chamber is connected to the air inlet of the waste heat boiler and the air inlet of the low-speed sludge drying equipment, respectively. The gas outlet of the low-speed sludge drying equipment is connected to the air inlet of the high-speed sludge drying equipment. The discharge port of the high-speed sludge drying equipment is connected to the inlet of the connecting section, and the discharge port of the connecting section is connected to the inlet of the low-speed sludge drying equipment.

2. The sludge drying system according to claim 1, characterized in that, The connecting section includes a screw conveyor and a sealing device; the feed end of the screw conveyor is connected to the discharge port of the high-speed sludge drying equipment, and the discharge end of the screw conveyor passes through the sealing device and is connected to the feed port of the low-speed sludge drying equipment.

3. The sludge drying system according to claim 1, characterized in that, It also includes exhaust gas purification facilities; the exhaust port of the waste heat boiler is connected to the air inlet of the exhaust gas purification facilities, and the exhaust end of the exhaust gas purification facilities is provided with a reuse pipe that connects to the interior of the high-speed sludge drying equipment.

4. The sludge drying system according to claim 1, characterized in that, It also includes a sealing cover, a combustion-supporting fan, and an emergency deodorization device; the exhaust port of the sealing cover is connected to the air inlet of the combustion-supporting fan, and the exhaust port of the combustion-supporting fan is connected to the air inlet of the insulated combustion chamber; the exhaust pipe of the sealing cover is connected to the air inlet of the emergency deodorization device through a bypass branch pipe; and a regulating valve is installed on the inlet air pipe of the combustion-supporting fan.

5. The sludge drying system according to claim 3, characterized in that, It also includes a high-concentration odor treatment device and a sludge silo; the exhaust port of the high-speed sludge drying equipment and the exhaust port of the sludge silo are both connected to the air inlet of the high-concentration odor treatment device; the high-concentration odor treatment device is sequentially connected to a washing device, a demisting device, an adsorption purification device and a second exhaust stack along the gas flow direction; the exhaust gas purification facility is sequentially connected to a denitrification device, a waste heat recovery device, a desulfurization device and a dust removal device along the gas flow direction, and its exhaust port is connected to the first exhaust stack.

6. A sludge drying method, characterized in that, The sludge drying system described in any one of claims 1 to 5 includes the following steps: The sludge to be treated is fed into the high-speed sludge drying equipment for constant-speed drying. The sludge processed by the high-speed sludge drying equipment is fed into the low-speed sludge drying equipment through the connecting section for deceleration drying. The combustible gas generated by the biomass gasification furnace enters the insulated combustion chamber for combustion. The high-temperature flue gas generated in the adiabatic combustion chamber is diverted, with the first part entering the waste heat boiler and the second part entering the low-speed sludge drying equipment. The medium-temperature flue gas discharged from the low-speed sludge drying equipment is introduced into the high-speed sludge drying equipment, so that the overall flow direction of the flue gas is arranged in the opposite direction to the sludge conveying direction.

7. The sludge drying method according to claim 6, characterized in that, Segmented control is implemented based on the sludge drying kinetics boundary point: the sludge moisture content entering the high-speed sludge drying equipment is controlled within the range of 60%-40%; the sludge moisture content entering the low-speed sludge drying equipment is controlled within the range of 40%-30%.

8. The sludge drying method according to claim 6, characterized in that, The rotational speed of the cylinder of the low-speed sludge drying equipment is controlled to be 0.7 to 0.8 times that of the cylinder of the high-speed sludge drying equipment, so that the residence time of sludge in the low-speed sludge drying equipment is relatively extended. .

9. The sludge drying method according to claim 6, characterized in that, The temperature of the flue gas introduced into the low-speed sludge drying equipment is controlled to be .

10. The sludge drying method according to claim 6, characterized in that, The sludge drying system also includes a high-concentration odor treatment device, a combustion fan, exhaust gas purification facilities, and a first exhaust stack; The exhaust gas discharged from the high-speed sludge drying equipment is collected as high-concentration odor gas and fed into the high-concentration odor gas treatment device for purification; The overflowing waste gas around the drying system is collected as low-concentration odor gas and sent into the insulated combustion chamber by the combustion fan for high-temperature oxidation reaction. The flue gas after high-temperature oxidation reaction enters the waste heat boiler along with the first part of high-temperature flue gas. After heat exchange, it is purified by the tail gas purification facility and waste heat is recovered. Finally, it is discharged into the first exhaust stack.

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