CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority benefits to Chinese Patent Application No. 201910244241.3, filed on Mar. 28, 2019. The contents of all of the aforementioned applications are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a high-moisture sludge ultra-fine synchronizing deep-drying device and a method thereof, and in particular to a device and a process for deep dehydration of residual sludge, belonging to the sub-area of residual sludge from urban sewage treatment plant in the field of environmental protection.

BACKGROUND OF THE INVENTION

With the development of China's society and urbanization, the amount of urban sewage is increasing, the number of corresponding sewage treatment facilities is increasing, and the amount of residual sludge-by-product of sewage treatment is increasing as well. By 2017, the annual output of residual sludge in China has exceeded 40 million tons, while the harmless treatment rate is less than 10%. How to properly dispose of these continuously produced and increasingly large quantities of sludge has become an urgent problem to be solved in China's environmental protection.

The residual sludge produced by most domestic sewage treatment plants has a moisture content of more than 80 wt %. Sludge dehydration is a key step in the process of treatment. However, it is difficult to subject sludge to deep dehydration, which has become a bottleneck problem, limiting the harmless and resourceful treatment of sludge.

At present, the main processes of sludge dehydration and drying comprise solar drying, thermal drying, conditioning-pressure filtering dehydration, etc. The solar drying process can reduce the moisture content of the sludge to less than 10 wt % by utilizing the thermal effect of solar energy, so as to achieve the purpose of deep drying, but it is difficult to be widely applied due to large covering area, long treatment time cycle and great influence of change with weather. The thermal drying technology removes the moisture in the sludge through direct heating or indirect heating, and the moisture content of the sludge can be reduced to less than 40 wt %, and further reducing in the moisture content will require a substantial increase in energy consumption. Conditioning-pressure filtering dehydration technology can reduce the moisture content of the sludge to 60 wt % by treating residual sludge with a conditioner to improve the dehydration performance of the sludge, and then subjecting the sludge to pressing and dehydration using a filter press. The above process can quickly remove the moisture in the sludge, but the degree of dehydration is limited, and it is difficult to achieve deep drying of the sludge (a moisture content of equal to or less than 20 wt %).

Therefore, the current development direction is to further reduce the moisture content of the semi-dry sludge produced by the thermal drying or mechanical dehydration process, and realize deep drying of the residual sludge rapidly and efficiently.

SUMMARY OF THE INVENTION

The present application aims to provide a high-moisture sludge ultra-fine synchronizing deep-drying device and a method thereof, which can increase the contact area by pulverizing the sludge, thereby improving the drying efficiency.

The present application is realized by the following technical solution.

A high-moisture sludge ultra-fine synchronizing deep-drying device, comprising a sludge ultrafine pulverizing unit and a sludge drying unit arranged horizontally in parallel, and a pulverized sludge discharge port arranged between the sludge ultrafine pulverizing unit and the sludge drying unit to communicate with each other;

wherein, the sludge ultrafine pulverizing unit comprises a sludge pulverizing chamber and a sludge feeding port arranged at one end of the sludge pulverizing chamber, and the sludge pulverizing chamber is a hollow cylindrical structure with a pulverizing rotation shaft horizontally arranged in the center, and the pulverizing rotation shaft is provided with a sludge pulverizing impeller; and a guiding baffle is arranged at a lower part of the sludge feeding port near a side of the sludge pulverizing impeller.

The sludge drying unit comprises a sludge drying chamber and a fluidizing rotation shaft arranged at a lower part of the sludge drying chamber, the fluidizing rotation shaft is arranged horizontally and concentric with the pulverizing rotation shaft; and the fluidizing rotation shaft is provided with a fluidizing impeller.

An upper part of the sludge drying chamber is provided with a mixing rotation shaft arranged horizontally, a plurality of mixing impellers are provided on the mixing rotation shaft, and the upper part of the sludge drying chamber is further provided with an air inlet located below the mixing impellers.

A lower part of the sludge drying chamber is provided with a dried sludge outlet arranged at a side away from the pulverized sludge discharge port; and the fluidized rotation shaft is arranged to be through the dried sludge outlet.

In the above technical solution, the sludge pulverizing impeller, the fluidizing impeller and the mixing impeller are all provided with a steering control unit.

In the above technical solution, the sludge pulverizing impeller comprises a plurality of blades uniformly arranged in a concentric circle with the pulverizing rotation shaft as the center, and an angle χ of 0° to 25° is formed between each of the blades and the axial direction of the pulverizing rotating shaft.

Preferably, the number of the blades is 4 to 8.

In the above technical solution, two or more sets of sludge pulverizing impellers are arranged along an axial direction of the pulverizing rotation shaft.

In the above technical solution, the lower part of the sludge feeding port is provided with a first deflector which is located above the pulverizing rotation shaft, and the first deflector is inclined downward along the traveling direction of the sludge with an inclination angle α of 15° to 30°.

In the above technical solution, the lower part of the sludge feeding port is provided with a second deflector, which is located below the pulverizing rotation shaft, and the second deflector is inclined downward along the traveling direction of the sludge with an inclination angle β of 15° to 60°.

In the above technical solution, a pulverizing sludge guiding module is annularly disposed on an inner wall of the sludge pulverizing chamber, the pulverizing sludge guiding module has a right-angled trapezoidal section, and the pulverizing sludge guiding module is arranged inside the pulverized sludge discharge port.

In the above technical solution, there are several sludge drying chambers arranged in parallel, the fluidized rotation shaft horizontally passes through the lower portion of the sludge drying chambers, and these several sludge drying chambers arranged in parallel to form a multi-stage sludge drying chamber comprising at least a first sludge drying chamber, and a next sludge drying chamber.

In the above technical solution, the dried sludge outlet is provided with a moving guiding module and a fixed guiding module; the fixed guiding module is semi-annularly disposed at the bottom of the sludge drying chamber, and an upper portion of the fixed guiding module is provided with a guiding slope that contracts toward the outlet direction; and the moving guiding module is a block that is capable of moving up and down.

In the above technical solution, the guiding slope has an inclination angle η of 45° to 70°.

In the above technical solution, one side of the block shows an obtuse angle triangle which expending and decreasing gradually from top to bottom, and the obtuse angle γ of the obtuse triangle is 120° to 160°; the other side of the block is a plane that is attached to the vertical wall of the sludge drying chamber.

In the above technical solution, there are at least two fluidizing impellers arranged axially along the fluidizing rotation shaft; each fluidizing impeller comprises a plurality of fluidizing blades, and an axial angle ε of 0° to 10° is formed between the fluidized blades and the fluidizing rotation shaft.

In the above technical solution, each of the mixing impellers comprises a plurality of mixing blades, and an axial angle φ of 0° to 15° is formed between the mixing blades and the mixing rotation shaft.

In the above technical solution, the device further comprises a separation collection chamber arranged behind the sludge drying chamber.

A method of sludge ultra-fine synchronizing deep-drying is provided, the method comprising the following steps:

pulverizing high-moisture sludge into coarse sludge particles which are fed into the sludge pulverizing chamber through the sludge feeding port, and adjusting rotation speed of the pulverizing rotation shaft to pulverize the sludge coarse particles passing the sludge pulverizing impellers into sludge powders, and transferring the sludge powders upon the pulverizing rotation shaft to the pulverized sludge discharge port as rotation of the pulverizing rotation shaft and pushing the sludge powders into the sludge drying chamber from the pulverized sludge discharge port;

adjusting rotation speed of the fluidized rotation shaft, so that the sludge powders are fluidized in the sludge drying chamber under a disturbance of the fluidizing impeller; and introducing dry air from an air inlet to mix it with the fluidized sludge powders in the sludge drying chamber and dry the sludge powders;

adjusting rotation speed of the mixing rotation shaft, so that the fluidized sludge powders in the sludge drying chamber are uniformly mixed with the dry air, and the sludge powders are sufficiently dried to become dried sludge powders and discharged from the dried sludge outlet; and

separating and collecting the dried sludge powders.

The sludge ultra-fine synchronizing deep-drying device has several sludge drying chambers arranged in parallel, forming a multi-stage sludge drying chamber comprising at least a first sludge drying chamber, a second sludge drying chamber, and/or a last sludge drying chamber, and the method further comprises the following steps:

pulverizing high-moisture sludge into coarse sludge particles which are fed into the sludge pulverizing chamber through the sludge feeding port, and adjusting the rotation speed of the pulverizing rotation shaft to pulverize the sludge coarse particles passing the sludge pulverizing impellers into sludge powders, and transferring the sludge powders upon the pulverizing rotation shaft to the pulverized sludge discharge port as rotation of the pulverizing rotation shaft, and pushing the sludge powders into the first sludge drying chamber from the pulverized sludge discharge port;

adjusting the rotation speed of the fluidized rotation shaft, so that the sludge powders are fluidized in the first sludge drying chamber under the disturbance of the fluidizing impeller; and introducing dry air from an air inlet to mix it with the fluidized sludge powders in the first sludge drying chamber and dry the sludge powders;

adjusting the rotation speed of the mixing rotation shaft, so that the fluidized sludge powders in the first sludge drying chamber are uniformly mixed with the dry air, and the sludge powders are sufficiently dried to become dried sludge powders;

allowing the dried sludge powders from the dried sludge outlet of the first sludge drying chamber into the second sludge drying chamber, and repeating the above drying process in the second sludge drying chamber until dried sludge powders are obtained and discharged from the dried sludge outlet of the last sludge drying chamber; and

separating and collecting the dried sludge powders.

In the above technical solution, the high-moisture sludge has a moisture content of 35 wt %-60 wt %; and the dried sludge has a moisture content of 10 wt % to 30 wt %.

In the above technical solution, the sludge coarse particle has a particle size of 0.5 cm to 3 cm; and the sludge powder has a particle size of 10 μm to 300 μm.

In the above technical solution, the pulverizing rotation shaft has a rotation speed of 1000 r/min to 3000 r/min; the fluidized rotating shaft has a rotation speed of 500 r/min to 1200 r/min, and the mixing rotation shaft has a rotation speed of 300 r/min to 1500 r/min.

In the above technical solution, the dry air has a temperature of 20° C. to 80° C.

The present invention has the following advantages and beneficial effects: pulverizing the sludge into fine particles can significantly increase the contact area between the sludge and the air, the airflow temperature required for drying is reduced, and the sludge drying efficiency is improved. Improving in drying efficiency greatly reduces the moisture content of drying the sludge from 40 wt % to less than 20 wt %, thereby increasing the scope and economy of reclamation disposal of the sludge end.

