Sludge Hollow Blade Drying Machine
Introduction
With the continuous improvement of urbanization level in China, the construction of sewage treatment facilities has been developed at a high speed, but the construction and operation of sewage plants have produced a large number of excess sludge. Calculating based on the water content of 80%, the total annual water content in sludge production will soon exceed 30 million tons, and the situation of sludge treatment is getting more and more serious.
During the construction of sludge plants, for a long time, there is a situation of "value water while neglect sludge". Therefore, although the urban sewage treatment plants in China have basically realized the preliminary reduction of sludge, but have not realized the stabilization treatment of sludge. According to statistics, about 80% of the sewage plants have sludge concentration and dehydration facilities, which has reached a certain degree of reduction. About 80% of the sludge has not been stabilized, and the sludge contains stench substances, pathogens, persistent organic compounds and other pollutants transferred from sewage to land, resulting in the further diffusion of pollutants, which greatly reduces the environmental emission reduction benefits of the large sewage treatment facilities that have been built and put into operation. The vast majority of sludge from landfill, open-air stacking and transportation belong to random disposal, and the proportion of real safe disposal is not more than 20%. Simple handling of land encroachment is serious, and it is not easy to find a proper site. Meanwhile, if the seepage prevention technology is not enough, it will lead to potential soil and groundwater pollution. For a long time, for the overall environment, it is equivalent to the lack of effective treatment of sewage. Especially, the disposal of high pollution and dangerous waste, such as chemical sludge, is more urgent.
To sum up, the comprehensive utilization of sludge resources will accelerate the sustainable development of economy. As an important part of disposal process, the sludge drying technology has now been quite mature, which can achieve a large number of continuous, fully closed operations. VAPORUN has made a series of optimization and improvement of sludge drying system, thus becoming the most professional sludge drying equipment manufacturing enterprise in China.
Major sludge categories for drying
Municiple sludge, chemical sludge, kaolin sludge, oil field sludge, textile sludge, paper pulp sludge, pigment sludge, metal sludge, etc.
Objectives of sludge drying
1）Minimization
2）Harmlessness
3）Resource recovery
Descriptions
The equipment can indirectly heat or cool paste, granule, powder and slurry materials, and can complete drying, cooling, heating, sterilization, reaction, low temperature combustion and other unit operations. The special wedged stirring and heat transfer blade in the equipment has high heat transfer efficiency and self-cleaning function of heat transfer surface.
The hollow shaft is lined with wedged hollow blades, and the thermal medium flows into the hollow blades through hollow shaft. The heat transfer area within each effective volume is very large. The temperature of heat medium which can be which can be water vapor or liquid type such as hot water, thermal oil and so on is ranged from 0 ℃ to 320 ℃. With the heating method of indirect conduction, there is no heat loss taken away by air, so all the heat is used to heat materials. The heat loss is only the heat dissipation to the outside environment through the insulation layer of equipment body. The heat transfer surface of wedged blade has cleaning function. The relative motion between the material granules and the wedged surface produces washing effect, which can wash off the attached materials on the wedged surface so as to keep the heat transfer surface clean in operation all the time. The shell of the blade dryer is in Ω shape, and generally 2-4 hollow stirring shafts are installed inside the shell. The shell has sealing cover and upper cover, which play a full role in preventing material dust leakage. The heat transfer medium flows through the shell jacket and the hollow stirring shaft through the rotating joint, and the hollow stirring shaft has different internal structures according to the types of different heat media, in order to ensure the best heat transfer effect.
Features
1)Reduction of energy consumption of blade dryer: As a result of indirect heating, there is no large amount of air to carry away the heat. The outer wall of the dryer is provided with an insulation layer. For slurry materials, only 1.2kg water vapor is needed to evaporate 1kg water.
2)The cost of the blade dryer is low: With large heat transfer area in unit effective volume, processing time is shortened and equipment size becomes smaller. Therefore, the building area and building space are greatly reduced.
3)A wide range of materials can be handled: Different thermal media can be used to deal with not only thermal sensitive materials, but also materials that need to be treated at high temperature. Common heating sources can be water vapor, thermal oil, hot water, cooling water, etc. This equipment can be operated continuously or intermittently, and can be used in many fields.
4)Less environmental pollution: no air carrier, so powder material is very rarely carried. The solvent evaporation of materials is very small, which is easy to handle. Closed circuit circulation can be used for pollutant materials or solvent recovery required conditions.
5)Low operation costs: The normal operation of this equipment is only 1 hour per day and per man. Low speed stirring with reasonable structure. The amount of wear is small and the cost of maintenance is very low.
6)Stable operation: Due to the special compression-expansion stirring effect of the wedged blade, the material granules are fully in contact with the heat transfer surface. In the axial range, the temperature, humidity and mixing gradient of the material are very small, thus ensuring the stability of the process.
Application
Hollow blade dryer has been successfully used in food, chemical, petrochemical, dye, industrial sludge and other fields. The properties of heat heat transfer, cooling and stirring has enabled the hollow blade dryer to complete the following unit operations: combustion (low temperature), cooling, drying (solvent recovery), heating (melting), reaction and sterilization. At the same time, the stirring blade is also the heat transfer surface, which increases the heat transfer area per unit effective volume and shortens the processing time. Also the heat transfer surface of wedged blade has the function of self-cleaning. The compression-expansion stirring function makes the material mix evenly. The material moves along the axial direction into "piston flow". In the axial range, the temperature, humidity and mixing gradient of the material are very small. Using heat conduction oil as heat medium, blade dryer can complete low temperature combustion. For example, calcium sulfate dihydrate (Ca2SO4 ·2H2O) is converted to calcium sulfate semi-hydrate (Ca2SO4 ·1/2H2O), sodium bicarbonate (NaHCO3) is converted to soda (Na2CO3) by combustion, etc. Through the cooling medium, such as water, cooling salt water, etc., this equipment can also be used for cooling. For example, the blade-type cool alkali machine applied in the sodium carbonate industry has replaced the old-type air cooling cool alkali machine, which has saved energy consumption and investment on tail gas treatment, and reduced operation costs. The main function of this kind of drying equipment is that the hot air is not used, so that the solvent recovery, the energy consumption and the environment control are in an ideal state of being easy to process. The hollow blade dryer is particularly suitable for the solvent requiring recovery as well as flammable and oxidizing thermal sensitive materials. It has been widely used in fine chemical, petrochemical, dye industry. The uniformity of temperature, humidity and mixing in the axial range makes the equipment available for heating or melting, or for some solid material reactions. It has been successfully used in the compound fertilizer and denatured powder industries. Blade dryers can also be used to sterilize food and flour. With a large heating area per unit effective volume, the material is quickly heated to sterilization temperature, which avoids heating for a long time and changing the quality of the material.
Schematic of Structure
1)Steam as heating source
2)Thermal oil as heating source
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Introduction
With the continuous improvement of urbanization level in China, the construction of sewage treatment facilities has been developed at... |
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