Low-temperature dehumidification sludge dryer

1. Low-temperature dehumidification sludge dryer

Low-temperature dehumidification sludge dryer is a kind of equipment specially used for sludge treatment. It adopts low-temperature dehumidification technology to remove moisture from sludge, so as to achieve the purpose of reducing, stabilizing, harmless and resource utilization.

2. Working principle

Heat pump dehumidification principle and hot air drying: Using the heat pump dehumidification principle, the wet sludge is dehydrated and dried by convection hot air drying. The wet air enters the dehumidification heat pump system, and the temperature of the wet air is lowered below the dew point by cooling, and the water vapor is condensed and discharged. After passing through the condenser, the air is heated to become hot dry air and then sent to the mesh belt drying system to continue drying the sludge. The air is recycled and reused, and no tail gas is generated.

Sludge treatment process:

Feeding: After the sludge is filtered from the plate and frame filter press, it is fed into the wet mud feed port of the dryer through the wet sludge feeding hopper and the screw conveyor, and then falls on the mesh belt after being processed by the mixer and the molding machine. The speed of the mesh belt sludge can be adjusted according to the moisture content required for drying4.

Drying: The hot dry air rises quickly from the bottom of the mesh belt and fully contacts the sludge to dry the sludge. The whole process is fully enclosed, and there is no heat loss in the drying hot air.

Discharge: The dried sludge is transported out of the drying system by a fully enclosed screw conveyor, and then transported to a qualified sludge disposal company for subsequent treatment such as sludge landfill, incineration or making into building materials.

3. Advantages compared with traditional drying methods

(I) Energy consumption

High energy efficiency ratio: Adopting the air energy principle, the drying process is closed and circulated, and the energy efficiency ratio reaches 1:3.5 or more. Compared with traditional medium and high temperature drying methods, the energy consumption is low, such as the traditional medium temperature belt type, rotary drum type, rotary disc type, paddle type, etc., which use coal or electric heating methods, with high energy consumption and low energy efficiency, while the low temperature dehumidification sludge dryer has good energy saving effect.

(II) Environmental impact

No odor generation: Low temperature (such as 68 degrees) safe operation, no odor generation, while traditional medium and high temperature drying methods are mostly open, sludge odor overflow pollutes the environment. In addition, the amount of H₂S and NH₃ precipitation during the operation of the equipment is greatly reduced. It adopts a fully enclosed structure design, no odor escapes during the whole process, no deodorization device needs to be installed, and environmental protection procedures and environmental impact assessments are simple and easy to pass.

No waste heat emission: No waste heat emission during the drying process, reducing thermal pollution to the environment, which is a problem with traditional drying methods.

(III) Safety performance

No explosion hazard: Under constant pressure, there is no explosion (dust explosion) hazard. During operation, the oxygen content of the sludge drying process is <12%; the dust concentration is <60g/m³; the particle temperature is <60, which is safe and reliable, and does not require nitrogen flushing operation, while traditional drying methods have certain safety risks.

(IV) Operation and maintenance

Simple operation and convenient maintenance: The system is fully automatic, the overall structure is modular, the operation and maintenance are simple, there are few vulnerable and consumable parts, and the service life is long. For example, the main body of the equipment is made of corrosion-resistant materials such as stainless steel, the heat exchanger is made of highly corrosion-resistant materials, and the nano-coating is treated for corrosion resistance. The service life can reach more than 15 years, and there is no mechanical wear during operation.

(V) Cost

Save multiple costs:

Land cost: It can be installed in the basement to save land area. The equipment can be placed up and down. Each ton of mud occupies 2m², and the average ton of mud occupies about 4m². Compared with the traditional method, it occupies a smaller area, and there is no complex civil engineering structure and infrastructure, which saves civil engineering costs.

Labor cost: The drying process is fully automatic, saving a lot of labor costs.

Transportation cost: It can directly dry sludge with a moisture content of 82% to 10%, without the need for segmented disposal, reducing the volume by 67% and the weight by 80%, which can save a lot of later transportation costs, and can be suitable for sludge dispersion or centralized treatment mode, saving sludge transportation costs and reducing environmental pollution during transportation1.

Condensate treatment cost: Condensate (sludge moisture) is simple to handle (or directly discharged), saving the cost of condensate treatment during the drying process.

4. Scope of application

Applicable to sludge drying treatment in industries such as industrial sludge, domestic sludge, chemical sludge, electroplating sludge, leather sludge, pharmaceutical sludge, pesticide sludge, food sludge, etc., and is also widely used in municipal sludge drying. It can treat wet sludge with a moisture content of 83% - 40%, and dry sludge with a moisture content of 10% - 40%, with a reduction of 75%. It is suitable for sewage treatment plants of various sizes, especially small and medium-sized sewage treatment plants.

5. Application effect

Improvement of sludge properties: The moisture content of the treated sludge is reduced, the volume is reduced, and it is easy to collect, transport and reuse. The sludge resources after low-temperature drying can be recycled. For example, the organic matter in the sludge can be further used for biofuel or incineration power generation, and the sludge residue can be used to improve poor quality soil or building materials products.

Meet environmental protection requirements: The waste gas generated during the drying process is treated by dust removal equipment and can be discharged after meeting the local ecological environment protection standards, avoiding the secondary pollution problem caused by traditional treatment methods and meeting the requirements of modern environmental protection for sludge treatment.