Dry coal preparation

In China accounted for more than 2/3 of recoverable reserves of coal located in the serious water shortage areas Shanxi, Shaanxi, western Inner Mongolia and Ningxia, and therefore can not adopt now most big water-intensive wet cleaning method to improve coal quality. China's self-developed gas-solid two-phase flow air heavy medium fluidized bed coal preparation technology and composite dry sorting machine can better meet the sorting requirements of drought-deficient areas and easy muddy coal.

Air heavy medium fluidized bed dry coal preparation

Basic principle and characteristics of dry coal preparation by air heavy medium fluidized bed

(1) The process of fluidization

Air heavy medium fluidization is a method in which a particulate solid medium is brought into a fluid-like state by contact with a gas, as shown in FIG. 1(a), a container 1 having a vertical wall, and a distributor 2 at the lower portion. A plurality of uniform fine particles are stacked thereon. A U-shaped pressure measuring tube hole is placed in the lower portion of the granular layer, and a gas flow from the bottom 4 through the distributor 2 is carried out, and then discharged from the top of the container 1. As the gas stream passes through the bed, as the gas flow rate increases, the entire fluidization process has three basic stages: 1 fixed bed; 2 fluidized bed; 3 transport bed. See Figures 1(b) (c) and (d), respectively.

Picture 4

Figure 1 Ideal fluidization process

(2) Fluid-like properties of a fluidized bed

Whether the gas-solid fluidized bed can have liquid mobility is very important for the air heavy medium fluidized bed sorting technology. Studies have shown that the gas-solid fluidized bed after complete fluidization looks like a boiling liquid and exhibits fluid-like properties in many respects. as shown in picture 2.

The two connected beds can be automatically adjusted to the same horizontal plane [Fig. 2];

Picture 5

Figure 2 Fluid-like properties of gas-solid liquefied beds

Double Cone Vacuum Dryer

Heat energy (hot water, low-pressure steam or heat transfer oil) is introduced into the closed interlayer, and the heat is transferred to the dried material through the inner shell. Driven by power, the tank body rotates slowly, the materials in the tank are constantly turned and mixed, and the heat is received from the inner surface of the wall, so as to achieve the purpose of strengthening drying. The material is in a vacuum state, and the vapor pressure drops to make the water (solvent) on the surface of the material reach a saturated state and evaporate, and is discharged and recovered by a vacuum pump in time. The moisture (solvent) inside the material continuously penetrates, evaporates and discharges to the surface. The three processes are carried out continuously, and the material achieves the purpose of drying in a short time.

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