Continuous sludge pre-drying method and system thereof
By using a continuous sludge pre-drying system and adsorbent treatment, the problems of low sludge pre-drying efficiency and high cost were solved, achieving rapid and stable sludge dewatering and reducing energy consumption and reagent costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUHAN TIANYUAN GROUP CO LTD
- Filing Date
- 2025-03-10
- Publication Date
- 2026-06-09
AI Technical Summary
Existing sludge pre-drying technologies suffer from low drying efficiency, high cost, and unstable results. In particular, mechanical dewatering processes involve high power consumption, high reagent costs, and complex operation.
A continuous sludge pre-drying system is adopted, including a sludge storage device, a sludge cutting device, a primary mixing device, a pre-drying device, and a secondary mixing device. Combined with acid leaching and pyrolysis activation treatment of the adsorbent, the system utilizes a multi-stage mixing and cutting process to enhance the hydrophilicity and adsorption capacity of the sludge, reduce sludge stickiness, and improve dewatering efficiency.
It enables continuous and rapid pre-drying of sludge, reduces energy consumption and reagent costs, improves sludge dewatering effect, reduces the possibility of secondary sludge agglomeration, and enhances the stability and efficiency of sludge drying.
Smart Images
Figure CN120081573B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sludge treatment technology, specifically to a continuous sludge pre-drying method and system. Background Technology
[0002] Early sludge pre-drying technology mainly relied on natural sun-drying, spreading the sludge thinly on a drying site to receive direct sunlight or constructing a greenhouse for indirect sunlight. This required a long drying cycle, was greatly affected by the climate, and the pre-drying effect was unstable. Large clumps of sludge were not effectively broken up, resulting in sludge that was "dry on the outside and wet on the inside." Nowadays, sludge pre-drying technology mainly focuses on mechanical dewatering, which mainly uses sludge dilution + chemical conditioning + mechanical dewatering methods. These methods can be mainly divided into centrifugal dewatering, belt filter press dewatering, and plate and frame dewatering. Centrifugal dewatering consumes a lot of electricity and generates a lot of noise during operation, and the resulting sludge cake has a high moisture content, generally 80-85%, with limited pre-drying effect. Belt filter presses are a commonly used dewatering equipment in recent years. They apply pressure to the filter cloth, using the pressure and tension of the filter cloth to dewater the sludge. This equipment requires frequent cleaning of the filter cloth, consumes a lot of backwash water, generates more secondary wastewater during backwashing, and the dewatering effect is not ideal. Plate and frame filter presses have the lowest sludge cake moisture content, generally around 60%-70%, but plate and frame dewatering is intermittent, inefficient, cumbersome to operate, and requires a lot of maintenance. All three of the above pre-drying methods have technical problems such as large amounts of reagents and high reagent costs. In the process of deep sludge drying treatment, the high moisture content of the pre-dried sludge at the front end greatly reduces the efficiency of subsequent sludge drying treatment and increases the drying operation cost. Summary of the Invention
[0003] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a continuous sludge pre-drying method and system, which solves the technical problems of low drying efficiency, high cost and unstable pre-drying effect in the sludge pre-drying process in the prior art.
[0004] To achieve the above technical objectives, the present invention provides a continuous sludge pre-drying system, comprising a sludge storage device, a sludge cutting device, a primary mixing device, a pre-drying device, and a secondary mixing device arranged sequentially. An adsorbent adding device is provided between the sludge cutting device and the primary mixing device. A vibrating screen is added to the sludge storage device, and the screen vibrates up and down electrically. A conveying device is used to transfer the sludge between the sludge storage device, the sludge cutting device, the primary mixing device, the pre-drying device, and the secondary mixing device. The conveying device can be at least one of a screw conveyor and a scraper conveyor. The sludge cutting device can be at least one of a shredder, a colloid mill, or a noodle machine.
[0005] Preferably, the pre-drying device is one of the following: a drum dryer, a spray dryer, a fluidized bed dryer, a vacuum belt dryer, a convection disc dryer, or an airflow dryer.
[0006] Preferably, a negative pressure fan and a condenser are connected in sequence to the air outlet pipe of the pre-drying device, and the generated condensate is discharged into the sewage treatment system for treatment and discharged in compliance with standards.
[0007] Preferably, the primary or secondary mixing device is one of a biaxial blade mixer, a roller mixer, and a ball mill mixer. Both the primary and secondary mixing devices are equipped with a variable frequency stirring device, with a stirring speed set to 3–10 rpm.
[0008] The present invention also provides a continuous sludge pre-drying method for the system described above, comprising the following steps:
[0009] S1. The sludge in the sludge storage device is transported to the sludge cutting device for cutting the sludge into strips;
[0010] S2. Add adsorbent to the sludge after it is cut into strips to obtain mixed sludge, and then transport the mixed sludge to a primary mixing device for primary crushing and mixing.
[0011] S3. The sludge discharged from the primary mixing device is sent to the pre-drying device for pre-drying, and the pre-dried sludge is sent to the secondary mixing device for secondary crushing and mixing to obtain pre-dried sludge.
[0012] Preferably, the sludge in S1 has a moisture content of 80% to 85%.
[0013] Preferably, the amount of adsorbent added in S2 is 10% to 40% of the dry weight of the sludge.
[0014] Preferably, the adsorbent in S2 is one of industrial activated clay or diatomaceous earth.
[0015] Preferably, the adsorbent needs to undergo acid leaching and pyrolysis activation treatment. The acid leaching involves adding the adsorbent to dilute phosphoric acid with a volume concentration of 5%-20%, keeping it at a temperature of 70-90℃ for 1-3 hours, rinsing it, and then drying it in a drying oven at 100-140℃ for 1-3 hours. The pyrolysis activation treatment involves pyrolyzing the acid-leached adsorbent in L-amino acids at a pyrolysis temperature of 220-320℃ for 1-5 hours, introducing amino groups, and compounding the adsorbent surface to enhance hydrophilicity and adsorption sites.
[0016] Preferably, the adsorbent after acid leaching and pyrolysis activation is rinsed with oxalic acid solution (volume concentration of 8%-14%) to further remove residual metal oxides, and then stirred at room temperature for 2-4 hours before being dried in a drying oven at 100-140°C for 1-3 hours.
[0017] Compared with the prior art, the beneficial effects of the present invention include:
[0018] (1) By setting up a sludge cutting device and a multi-stage circulating mixing device, the sludge is fully crushed, increasing the contact area between the sludge and the adsorbent. Taking advantage of the high viscosity of sludge at high moisture content, the sludge particles are coated by the adsorbent under fully homogeneous mixing, reducing the viscosity of the sludge and eliminating the possibility of secondary agglomeration of sludge.
[0019] (2) After the adsorbent is treated with dilute phosphoric acid, metal oxide impurities such as Fe2O3 and Al2O3 and organic residues in the adsorbent can be gently removed and the pore structure optimized, and the pore connectivity enhanced. At the same time, after the phosphoric acid treatment, more Si-O bonds are exposed on the surface of the silicon-based adsorbent, which combine with water molecules through hydrogen bonds to form Si-OH, forming a stable hydrophilic layer and improving water absorption. After the phosphoric acid treatment, phosphate silicon compounds can be formed on the surface of the adsorbent, generating Si-OP bonds, introducing phosphate groups, and increasing the hydrophilicity of the adsorbent. The adsorbent is chelated with L-amino acids and pyrolyzed to introduce amino groups, further enhancing the structural stability, improving the surface hydrophilicity and the density of water molecule adsorption sites.
[0020] (3) Free water and adsorbed water in sludge are transferred from the difficult-to-dehydrate sludge to the adsorbent material that is easier to dehydrate, which reduces the energy consumption cost of sludge pre-drying and realizes continuous and rapid pre-drying treatment of sludge. Attached Figure Description
[0021] Figure 1 This is a continuous sludge pre-drying system provided in a specific embodiment of the present invention. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0023] Example 1
[0024] like Figure 1This embodiment provides a continuous sludge pre-drying system, including a sludge storage device, a sludge cutting device, a primary mixing device, a pre-drying device, and a secondary mixing device arranged sequentially. An adsorbent adding device is provided between the sludge cutting device and the primary mixing device. A vibrating screen is added to the sludge storage device, and the screen vibrates up and down electrically. A conveying device, specifically a screw conveyor, is used to transfer sludge between the sludge storage device, the sludge cutting device, the primary mixing device, the pre-drying device, and the secondary mixing device. The sludge cutting device is a shredder. The pre-drying device is a drum dryer, with a negative pressure fan and a condenser connected sequentially to its outlet pipe. The generated condensate is discharged into a wastewater treatment system for treatment and meets discharge standards. The primary or secondary mixing device is a biaxial blade mixer. Both the primary and secondary mixing devices are equipped with variable frequency stirring devices with a stirring speed set to 3 rpm.
[0025] This embodiment also provides a continuous sludge pre-drying method for the system described above, including the following steps:
[0026] S1. The sludge in the sludge storage device is transported to the sludge cutting device for cutting the sludge into strips. The moisture content of the sludge is 80%.
[0027] S2. Add industrial activated clay to the sludge after it is cut into strips. The amount of adsorbent added is 10% of the dry weight of the sludge to obtain mixed sludge. The mixed sludge is then transported to a primary mixing device for primary crushing and mixing.
[0028] S3. The sludge discharged from the primary mixing device is sent to the pre-drying device for pre-drying, and the pre-dried sludge is sent to the secondary mixing device for secondary crushing and mixing to obtain pre-dried sludge.
[0029] The adsorbent requires acid leaching and pyrolysis activation treatment. Acid leaching involves adding the adsorbent to 5% (v / v) dilute phosphoric acid, maintaining the temperature at 90°C for 3 hours, rinsing, and then drying in a 100°C oven for 3 hours. Pyrolysis activation treatment involves pyrolyzing the acid-leached adsorbent in L-amino acids at 220°C for 5 hours, introducing amino groups to modify the adsorbent surface and enhance hydrophilicity and adsorption sites. After acid leaching and pyrolysis activation, the adsorbent is rinsed with 8% (v / v) oxalic acid solution to further remove residual metal oxides, stirred at room temperature for 4 hours, and then dried in a 100°C oven for 3 hours.
[0030] Experimental data: The sludge moisture content after the primary mixing unit was 78.4%, and the sludge moisture content after the secondary mixing unit was 60.3%.
[0031] Example 2
[0032] like Figure 1 This embodiment provides a continuous sludge pre-drying system, including a sludge storage device, a sludge cutting device, a primary mixing device, a pre-drying device, and a secondary mixing device arranged sequentially. An adsorbent adding device is provided between the sludge cutting device and the primary mixing device. A feeding vibrating screen is added to the sludge storage device, and the screen vibrates up and down electrically. A conveying device, specifically a scraper conveyor, is used to transfer sludge between the sludge storage device, the sludge cutting device, the primary mixing device, the pre-drying device, and the secondary mixing device. The sludge cutting device is a colloid mill.
[0033] The pre-drying device is a spray drying device (replacing the spray drying device with a fluidized bed drying device, a vacuum belt drying device, a convection disc drying device, or an airflow drying device has the same effect).
[0034] The pre-drying device has a negative pressure fan and a condenser connected sequentially to its outlet pipe. The resulting condensate is discharged into the wastewater treatment system for treatment and meets discharge standards. The primary or secondary mixing device is a roller mixer. Both the primary and secondary mixing devices are equipped with variable frequency stirring devices with a stirring speed of 10 rpm.
[0035] This embodiment also provides a continuous sludge pre-drying method for the system described above, including the following steps:
[0036] S1. The sludge in the sludge storage device is transported to the sludge cutting device for cutting the sludge into strips. The moisture content of the sludge is 85%.
[0037] S2. Add industrial activated clay to the sludge after it is cut into strips. The amount of adsorbent added is 40% of the dry weight of the sludge to obtain mixed sludge. The mixed sludge is then transported to a primary mixing device for primary crushing and mixing.
[0038] S3. The sludge discharged from the primary mixing device is sent to the pre-drying device for pre-drying, and the pre-dried sludge is sent to the secondary mixing device for secondary crushing and mixing to obtain pre-dried sludge.
[0039] The adsorbent requires acid leaching and pyrolysis activation treatment. Acid leaching involves adding the adsorbent to 20% (v / v) dilute phosphoric acid, maintaining the temperature at 70°C for 1 hour, rinsing, and then drying in a 140°C oven for 1 hour. Pyrolysis activation treatment involves pyrolyzing the acid-leached adsorbent in L-amino acids at 320°C for 5 hours, introducing amino groups to modify the adsorbent surface and enhance hydrophilicity and adsorption sites. After acid leaching and pyrolysis activation, the adsorbent is rinsed with 14% (v / v) oxalic acid solution to further remove residual metal oxides, stirred at room temperature for 2 hours, and then dried in a 140°C oven for 3 hours.
[0040] Experimental data: The sludge moisture content after the primary mixing unit was 76.8%, and the sludge moisture content after the secondary mixing unit was 56.3%.
[0041] Example 3
[0042] like Figure 1 This embodiment provides a continuous sludge pre-drying system, including a sludge storage device, a sludge cutting device, a primary mixing device, a pre-drying device, and a secondary mixing device arranged sequentially. An adsorbent adding device is provided between the sludge cutting device and the primary mixing device. A feeding vibrating screen is added to the sludge storage device, and the screen vibrates up and down in an electrically driven manner. A conveying device is used to complete the transfer of sludge between the sludge storage device, the sludge cutting device, the primary mixing device, the pre-drying device, and the secondary mixing device.
[0043] The pre-drying device has a negative pressure fan and a condenser connected sequentially to its outlet pipe. The resulting condensate is discharged into the wastewater treatment system for treatment and meets discharge standards. The primary or secondary mixing device is a ball mill mixer. Both the primary and secondary mixing devices are equipped with variable frequency stirring devices with a stirring speed of 7 rpm.
[0044] This embodiment also provides a continuous sludge pre-drying method for the system described above, including the following steps:
[0045] S1. The sludge in the sludge storage device is transported to the sludge cutting device for cutting the sludge into strips. The moisture content of the sludge is 83%.
[0046] S2. Add diatomaceous earth to the sludge after it is cut into strips. The amount of adsorbent added is 25% of the dry weight of the sludge to obtain mixed sludge. The mixed sludge is then transported to a primary mixing device for primary crushing and mixing.
[0047] S3. The sludge discharged from the primary mixing device is sent to the pre-drying device for pre-drying, and the pre-dried sludge is sent to the secondary mixing device for secondary crushing and mixing to obtain pre-dried sludge.
[0048] The adsorbent requires acid leaching and pyrolysis activation treatment. Acid leaching involves adding the adsorbent to 10% (v / v) dilute phosphoric acid, maintaining the temperature at 80°C for 2 hours, rinsing, and then drying in a 120°C oven for 2 hours. Pyrolysis activation treatment involves pyrolyzing the acid-leached adsorbent in L-amino acids at 250°C for 3 hours, introducing amino groups to modify the adsorbent surface and enhance hydrophilicity and adsorption sites. After acid leaching and pyrolysis activation, the adsorbent is rinsed with 11% (v / v) oxalic acid solution to further remove residual metal oxides, stirred at room temperature for 3 hours, and then dried in a 130°C oven for 2 hours.
[0049] Experimental data: The moisture content of the sludge after the primary mixing device was 77.40%, and the moisture content of the sludge discharged from the secondary mixing device was 58.33%.
[0050] Comparative Example 1
[0051] This comparative example is the same as Example 1, except that diatomaceous earth is replaced with an equal amount of dry sludge in this comparative example, and the moisture content of the dry sludge is 30%.
[0052] The sludge in the sludge storage device has a moisture content of 80%, the sludge after the primary mixing device has a moisture content of 79%, and the sludge discharged from the secondary mixing device has a moisture content of 70%.
[0053] It is evident that this invention solves the technical problems of long drying cycles, significant susceptibility to climate, difficulty in sludge dewatering, and high chemical additives in existing sludge pre-drying technologies, thereby reducing the pressure of subsequent sludge drying, lowering the operating costs of sludge drying, and achieving the harmlessness and volume reduction of sludge.
[0054] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A continuous sludge pre-drying method for a continuous sludge pre-drying system, the continuous sludge pre-drying system comprising a sludge storage device, a sludge cutting device, a primary mixing device, a pre-drying device, and a secondary mixing device arranged sequentially, wherein an adsorbent adding device is provided between the sludge cutting device and the primary mixing device, characterized in that, The continuous sludge pre-drying method includes the following steps: S1. The sludge in the sludge storage device is transported to the sludge cutting device for cutting the sludge into strips; S2. Add adsorbent to the sludge after it is cut into strips to obtain mixed sludge, and then transport the mixed sludge to a primary mixing device for primary crushing and mixing. S3. The sludge discharged from the primary mixing device is sent to the pre-drying device for pre-drying, and the pre-dried sludge is sent to the secondary mixing device for secondary crushing and mixing to obtain pre-dried sludge. The adsorbent needs to undergo acid leaching and pyrolysis activation treatment. The acid leaching involves adding the adsorbent to dilute phosphoric acid with a volume concentration of 5%-20% and keeping it at a temperature of 70-90℃ for 1-3 hours. After rinsing, it is dried in a drying oven at 100-140℃ for 1-3 hours. The pyrolysis activation treatment involves pyrolyzing the acid-leached adsorbent in L-amino acids at a pyrolysis temperature of 220-320℃ for 1-5 hours. The adsorbent after acid leaching and pyrolysis activation is rinsed with oxalic acid solution.
2. The method according to claim 1, characterized in that, The sludge described in S1 has a moisture content of 80% to 85%.
3. The method according to claim 1, characterized in that, The amount of adsorbent added in S2 is 10% to 40% of the dry weight of the sludge.
4. The method according to claim 1, characterized in that, The adsorbent mentioned in S2 is one of industrial activated clay or diatomaceous earth.
5. The method according to claim 1, characterized in that, The pre-drying device is one of the following: drum dryer, spray dryer, fluidized bed dryer, vacuum belt dryer, convection disc dryer, or airflow dryer.
6. The method according to claim 1, characterized in that, The pre-drying device has a negative pressure fan and a condenser connected in sequence to the air outlet pipe. The condensate produced is discharged into the sewage treatment system for treatment and discharged in compliance with standards.
7. The method according to claim 1, characterized in that, The primary or secondary mixing device is one of a biaxial blade mixer, a roller mixer, and a ball mill mixer.