1. Suction pneumatic conveying device
Suction pneumatic conveying device works by means of air flow with pressure less than 0.1 mpa. According to the different pressure, suction type can be divided into high vacuum type (0.01~ 0.05mpa) and low vacuum type (0.05~ 0.1mpa or more). When the air machine (vacuum pump) is started, it is pumped to a certain vacuum degree in the whole system of the instant noodle production line equipment. Under the influence of the pressure difference, the air flow in the big air passes through the clearance of the material pile, and the material is carried and then moved to the material storage tank along the conveying pipe 3. The air and the material are separated. The material is discharged by the rotary valve at the bottom of the storage tank, while the air flow containing dust continues to be sent to the dust collector, and the dust is discharged from the bottom. Finally, the dusted air is vented into the atmosphere through the fan and muffler. The greatest advantage of this device is that the feeding is simple and convenient, the distance from several or a pile of materials and the productivity is limited because the pressure difference of the device system is not large. Its vacuum degree generally does not exceed 0. 05~0.06MPa, if the vacuum degree is too low, it will sharply reduce its carrying capacity, resulting in pipe blockage. It also requires a high degree of tightness. In addition, in order to ensure the reliable operation of the fan and reduce wear and tear of parts, the air into the fan must be pre-dedusting.
To protect the environment and system exhaust equipment, can use two - stage dust removal. The first stage adopts cyclone precipitator, and the second stage mostly adopts bag precipitator, which is simple, reliable, easy to operate and maintain, and high dust removal efficiency. The general combined efficiency should not be less than 99%. The dust collector should be strict when discharging ash, do not blow to the device; The suction equipment produces negative pressure for the system and is one of the key equipment in the system.
At present, the maximum output of the domestic negative pressure pneumatic conveying system can reach 40t/h. The conveying distance is within 200m, and the maximum mixing degree of conveying is 20. The operation of the whole system has basically realized the program control.
2. Pneumatic conveying device of compression type
It operates above 0.1 mpa. Compression type can be divided into high pressure type (0.1~ 0.7 MPa) and low pressure type (less than 0.05MPa). The high-pressure air generated by the fan enters into the human storage tank, and water gas is separated through the soda separator. If the air and the material mixture move along the material transfer pipe, the material is discharged through the separator at the bottom of the storage bin, and the air is purified by the dust remover. The characteristics of this device are exactly the opposite of the suction type. Because it is convenient to install bifurcation pipeline, it can transport materials to several places at the same time, and transport distance is long, high productivity. In addition, it is easy to find the leak location, and the dust removal requirements for the air are not high. Its main disadvantage is that it has to supply materials from the low pressure to the high pressure feeding pipe, so the feeding device is more complex, and can not or difficult to absorb materials from several places at the same time.
Pneumatic conveying system with large conveying pressure difference is suitable for long distance and large capacity conveying. Transmission distance
The maximum is up to 250m. Compared with the negative pressure pneumatic conveying system, the air purification is easier, but the air quality is strictly required, and impurities, water and oil must be prevented from entering the system.
The air pressure of low-pressure pneumatic conveying system is lower than 0.05mpa, and the material/gas ratio is less than 5 (the maximum particle material can reach 15). The critical gas speed is 10 ~ -25m/s. It can be seen that the conveying pipe is more worn, the air consumption is large, and the dust collector's load is large.
3. Comprehensive pneumatic conveying device
The comprehensive pneumatic conveying device is shown in FIG. 1-5, which is composed of suction type part and compression type part. First, the material is transferred from the feeding tube 2 to the feeding tube 3 through the suction nozzle 1, and then to the separator 3. The separated material is then sent to the feeding tube 2 of the feeding system for further transmission.
This form combines the advantages of suction type and pressure type, which can not only absorb materials from several places, but also transport materials to several places at the same time, and the transport distance can be long. The main disadvantage is that the dusty air has to pass through the blower, making its working conditions worse, and the structure of the whole device is also more complex.
To sum up, in the equipment of non-fried instant noodle production line, no matter how the form of the device is different, no matter how the fan supplies energy, they are always composed of the energy supply part, the material transport part and the air purification part, just in different occasions, using different forms of the device.
Pneumatic conveying device is more suitable for the class of large output of instant noodles production line, its characteristics are high degree of automation, good conveying effect, conveying flow regulation is convenient, and wheat flour after the wind is relatively loose, conducive to the contact with water. But its structure is complex, the cost is high, and has certain requirements on the height of the plant, also increased infrastructure investment.