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With the strengthening of environmental awareness and the comprehensive utilization of fly ash in various thermal power plants, pneumatic ash transport systems have been widely used. However, if the pneumatic ash conveying equipment is clogged during use, it will cause us unnecessary trouble, so why does this phenomenon occur? Generally speaking, it is divided into the equipment itself and non-equipment factors. Today we will tell you Non-equipment factors.
First, the gas source:
The pressure, flow rate and air quality of the gas used in the pneumatic ash conveying system have a great impact on the transportation characteristics. The compressed air needs to undergo a series of treatments such as filtering and drying, and the air volume should leave a certain amount of wealth.
Pneumatic conveying is conveyed by gas. The pressure of the gas source must overcome the resistance of the warehouse pump, the resistance of the pipeline and the pressure of the pneumatic ash conveyance. If the pressure head is not enough, the pipe will be easily blocked.
Insufficient gas volume increases the ratio of ash to gas, and the conveying concentration is too large, resulting in increased pipeline resistance and prone to blockages. If the air pressure is too high, the ash-gas ratio will decrease, and the pipeline will be abraded.
The gas source has impurities, and the oil and water content will make the ash particles stick to each other, and the flow resistance will increase sharply, which will cause blockage of the pipe. Therefore, when it is found that the oil source contains a large amount of oil and water, the compressed air system should be inspected. If oil or water is discharged from the pipeline of an air compressor, the exit door should be closed and isolated as soon as possible, and the maintenance personnel should be contacted for elimination. Routine inspections should regularly open the gas storage tank drain door and check the oil and water content in the exhaust.
Second, changes in gray characteristics
Commonly, the main cause of pipe blocking is sedimentary ash, which mostly occurs in the ash blowing stage of the boiler and the unoperated high-voltage electric field warehouse pump. It mainly refers to the ash that drops to the ash bucket when the gravity is greater than the buoyancy of the flue gas, including the kerosene in the boiler ignition stage The ash settled by co-firing and the ash settled after the shutdown of the electric dedusting fault. The sedimentary ash generally has coarse particles and rough surface, and some oil-coal mixed ash has high viscosity (there is also a similar situation when ammonia escapes too much). During the transportation process, the pressure gradually decreases, resulting in the gradual sedimentation of the ash particles, which makes the slip layer thicker. The resistance increases, but the static pressure head does not increase, the slippage state becomes slower, the upper flow path is reduced, and the flow velocity is increased. Although it has the effect of driving the fly ash to fly again, the vertical speed difference at this time increases sharply and the speed gradient Increased, prone to blockage.
Third, the temperature
When the temperature is low in winter, it is easier to block pipes than in summer. This is because the surface of fly ash has many pores and cracks, and this structure has a strong adsorption effect on water. When the temperature of the ash is low, the water vapor adhering to the surface of the fly ash tends to dew, which increases the viscosity of the ash, which increases the internal friction, increases the flow resistance, and has poor fluidity, which causes tube blocking.
The above three are the common external factors that cause the blockage of pneumatic ash conveying system. Everyone needs to pay attention when using it.