I. Advantages and Shortages of Centrifugal Spray Congealer
ⅰMain advantages:
1. The completion of the market are very intensive these days. It is necessary to increase the processing capacity with plant. It is very difficult to increase the capacity with traditional design, while Centrifugal spray congealer could be very large, such as 20 tons per hour.
2. Powder and irregular flake materials are very hard to compete with the domestic and overseas suppliers. Regular pellets has the characteristics of lowest flying powder, good flowability and easy metering, well dispersion and easy dissolution, as well as stability, so the product is very competitive.
3) Centrifugal spray congealing technology is used to improve the operating conditions and environment, control the flying powder in the processes of granulation, transportion and packaging.
4) Compare to the traditional technology, centrifugal spray congealer has the advantages of large capacity, uniform pellets, high yield and convenient operation.
ⅱ. Main shortage
The investments on equipment and workshop are higher.
II. Design
The congealing process of melted material is generally divided into three stages: the first stage is pre-cooling process. The melted material is cooled from feeding temperature to melting point. The second stage is solidification, the melted material liquid will be solidified, and the temperature normally keeps almost the same in this period. The third stage is cooling and hardening of the solid material. The product will be cooled in this stage.
The time of the above three stages differs from each other according to the properties of different materials. In terms of the conversion process of the materials from liquid state to solid state inside the spray tower, we build a data model, which guides us to calculate the diameter of the tower body, so to choose the specification of the equipment.
To simplify the calculation, we make and assumption: a drop of material is to heat exchange with infinite cold air. We have get the following relative calculation:
Pre-cooling time of Melted material: θd(s): (Td-Tk)/(Tc-Tk)=ExP(Hdθd/DcPd)
Solidification time: θc(s): θc=DPcLf/Hc(Tc-Tk)
Cooling and hardening time: θs(s): (Tc-Tk)/(Ts-Tk)=ExP(Hsθs/DCsPs)
Td, Tc, Ts, Tk: the congealing temperature, solidifying point of melted material, discharging temperature of pellet product and cooling air temperature (°C)
Hd, Hc, Hs: the heat transfer factors between the material and cooling air during the periods of pre-cooling, solidification, cooling and hardening (Kcal/m3.s. °C)
Lf: Latent heat of solidification
Pd, Pc, Ps: The constant pressure density of the material when it is melted material liquid, during solidification, and already solidified (kg/m3)
D: Diameter of pellets (mm)
So we get the total time:
θ(s): θ=θd+θc+θs
Calculate based on the density of the product to calculate the lowering down speed Vt, so the height of the tower should be: H=θ*Vt-L
Calculate the running distance of material under centrifugal force (L), and decide the diameter of the tower. D=2L
III. Main Factors relating to congealing process
1. Material temperature: the material temperature influences the working capacity of the equipment. We normally consider the temperature between the melted material feeding temperature and melting point, or solidification temperature. The capacity is lower when the feeding temperature is higher. When the melted material temperature is too high (such as the temperature is more than 50°C higher than melting point or solidification temperature), it is suggest to cool the product before feeding, so to fully utilize the capacity of the equipment.
2. Property of the material. The solidification properties of different products are always different. The main properties that influences the congealing processes are melting point (or softening point), density, heat transfer factor, crystallization property, and viscosity (or surface tension) etc. The viscosity and surface tension mainly influence the quality of pellets, and others influence the cooling and solidifying speed, so to influence the capacity. Generally speaking, The higher melting point and density, the bigger heat transfer factor, the smaller latent heat, the bigger capacity, and vice versa.
Special Note: This kind machine has a extremely high collecting rate, almost no dust exhausted with the air. Some of our customers have produced hundreds tons of materials; the cyclone only collects less than 1kg fine powder. So there is need for one cyclone + bag filter. We normally suggest only one cyclone, or exhaust air directly from the drying tower.
IV. Technical Parameters
Specification
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ZLZ-500
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ZLZ-1000
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ZLZ-2000
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ZLZ-3000
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ZLZ-5000
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ZLZ-10000
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Air Inlet Temp.
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-20℃-20℃, Adjustable
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Air Exhaust Temp.
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20-40℃ (depend on the properties of the product, and URS)
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Nominal Processing Capacity
(Kg/h)
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500
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1000
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2000
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3000
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5000
|
10000
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Main Pellets Diameter Range
(µm)
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100-2000
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100-2000
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100-2000
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100-2000
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100-2000
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100-2000
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Cooling method
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Cooling dehumidifier
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Cooling Tower Diameter (mm)
|
6500
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8000
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8500
|
9000
|
9500
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10000
|
Overall Dimensions (m)
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According to the specification and plant layout
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Collection rate
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99-99.99%,depend on the properties of the product and configurations
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Remarks:
1. The above parameters are calculated according to the most popular congealing material (stearic acid). Provided that the material is different, the parameters will also be different. Please contact us before choose the specifications. And it is suggested to make trial before finalize the order
2. Cooling source: when the cooling source is different, the capacity of the same equipment could be very different. Please make sure use the cooling source required by us.