Moisture content of silica sand can reach below 0.5% by using fluidized bed dryer

Silica sand is the core raw material for glass production. Silica sand is generally produced by the wet sand washing plant. The finished silica sand after production contains a certain amount of water. The quartz sand itself is not soluble in water, that is to say, the quartz sand itself does not absorb water, and the finished quartz sand pile contains different degrees of water. During the process of accumulation, transportation, turnover and storage of wet quartz sand, the water in the finished quartz sand pile will leak out. Due to the different forms and locations of silica sand in the process of accumulation, transportation, turnover and storage, the degree of water seepage is also different, and the water left in each area of the quartz sand pile is also different. The water content at the bottom is higher than that at the top, and the water content in the middle is higher than that at the outside, so the consistency of the water content of quartz sand products is poor. Due to the poor consistency of the water content of quartz sand, the weighing error of quartz sand is large, and the fluctuation of the water content of the batch is also caused, which has a great impact on the glass quality. In order to reduce the water content of silica sand and stabilize it in the range of process requirements, the raw material of wet glass sand must be dried. In the past, the rotary dryer was often used for the drying of silica sand. The disadvantages of the rotary dryer are low thermal efficiency, high energy consumption, difficult to control the temperature of silica sand product at the outlet, and the dried silica sand still contains a certain amount of water, and the water fluctuation is also large. 

According to many years of experience in silica sand production and advanced drying technology, Sinonine technical team has developed a silica sand fluidized bed dryer system. Through a large number of production experience, it has been proved that the fluidized bed dryer system has high thermal efficiency and can fully meet the process requirements for controlling the moisture content of glass sand. After drying, the moisture content of silica sand can be less than 0.5%, and the moisture distribution is very uniform.

The silica sand fluidized bed dryer system is realized by the following technical processing. After mixing the high temperature flue air generated by natural gas combustion with ambient air at normal temperature, the flue air temperature is adjusted to the set range, and the high-temperature flue air after temperature adjustment is blown into the fluidized bed by the blower, and then the silica sand drying operation is continued according to the following steps.

1. Add wet silica sand into the fluidized bed dryer through the feeder.

2. In the fluidized bed dryer, the accurately calculated hot air flow flows through the air distribution plate of the fluidized bed, making the wet silica sand particles suspended in the air flow, forming a fluidized state.

3.Silica sand particles in fluidized state are uniformly mixed in the fluidized bed and fully contacted with the air flow for strong heat exchange.

4.The dried hot waste air enters the dust collector of the fluidized bed.

5. The ambient air is blown into the cooling part of the dryer through the blower to cool the dried silica sand. The cooled cold exhaust air also enters the dust collector of the fluidized bed and is mixed with the dried exhaust air. The mixed exhaust air is led away by the induced draft fan and discharged into the atmosphere.

6. The temperature of dried silica sand can be controlled below the set value, and the moisture content of silica sand is less than the set value.

7. The final dried silica sand enters the vibrating screen to collect qualified product.

After drying, the temperature of quartz sand can be lower than 60 ℃, and the moisture content of quartz sand can be less than 0.5%, with uniform distribution. The drying efficiency and production capacity of silica sand dried by this fluidized bed dyer system are in a controllable range, which can ensure that the moisture content of raw materials fluctuates little, and can ensure the production of stable and reliable glass products.

Figure 1 shows the drying method of silica sand in fluidized bed dryer

Fig 1.silica sand fluidized bed dryer system

The silica sand containing a certain amount of water is added into the hopper 1, and the material enters the feeder 12 through the hopper 1, and then enters the fluidized bed dryer 5; After the combustion of natural gas 3, the primary air mixing is conducted in the air mixing chamber 4. The high temperature flue air generated is then mixed with the ambient air 2 for secondary air mixing. After the secondary air mixing, the high temperature air of about 380 ℃ is blown into the lower part of the fluidized bed 5 through the fan 7. In order to ensure uniform air pressure, the hot air passes through the pressure equalizing box 14 and then enters the lower part of the air distribution plate 13. The high temperature air blows up the wet silica sand on the upper part of the air distribution plate through numerous small holes on the air distribution plate, The wet quartz sand particles are suspended in the air stream to form a fluidization state. The quartz sand is like boiled water, and the quartz sand is blown and dried by the high temperature air stream. The quartz sand particles are evenly mixed in the fluidized bed and fully contacted with the high temperature air flow for very strong heat exchange. Its drying strength can reach 300KgH2O/m2H. The dried waste air enters the dust collector 6 of the fluidized bed. The ambient air for cooling is blown into the cooling part of the dryer through the cooling blower 10. The cooled waste air of the quartz sand also enters the dust collector 6 of the fluidized bed and is mixed with the dried waste air. The mixed waste gas is led away by the dust collector fan and discharged into the atmosphere. The temperature of the dried quartz sand is lower than 60 ℃, and then enters the vibrating screen 8. Qualified quartz sand enters the next process 9.

The advantage of the quartz sand fluidized bed dryer is that the drying efficiency and production capacity of the wet quartz sand are controlled by the adjustable feeder. After natural gas combustion, it is mixed with ambient air at normal temperature twice to produce high-temperature flue air with controllable temperature. In the fluidized bed dryer, the accurately calculated hot air flow is uniformly distributed through the pressure distribution plate of the fluidized bed. In the fluidized bed, wet quartz sand particles are suspended in the air stream, forming a fluidization state. It is characterized by that the quartz sand particles in the fluidized state are uniformly mixed in the fluidized bed and fully contacted with the high temperature air flow to conduct very strong heat and mass transfer, and its drying intensity is high and its efficiency is high. After drying, the temperature of silica sand is lower than 60 ℃, the water content of quartz sand is less than 0.5%, and the water content distribution is very uniform.