The purpose of the auxiliary mill system is to make the crusher work to cause a large negative pressure under the screen, so that the qualified fine powder in the crushing chamber can quickly pass through the sieve hole, prevent the screen hole from being clogged, reduce the excessive crushing of the material, and improve The output of the pulverizer. At the same time, when the air enters the crushing chamber and passes through the sieve, it can effectively cool the crushing chamber and take away the heat and moisture generated by the crushing chamber. It has been proved by experiments that a good auxiliary suction system can increase the output of the pulverizer by more than 20% and avoid the clogging of the sieve holes and the condensation of subsequent processes. Of course, the excessive suction volume of the suction system should also be avoided to cause unnecessary power consumption and the negative effects caused by it. Therefore, it is of great significance to properly configure the pulverizer to assist the suction system. There are two basic elements for using auxiliary suction to increase the output of the pulverizer: First, the airflow must flow from the inlet to the pulverization chamber and be discharged through the sieve hole, so that the airflow can be an effective airflow for increasing the output of the pulverizer; Second, in order to increase the output more obviously, the air volume of the effective airflow must be large enough. Therefore, in the design of the entire structure, various factors must be considered in order to make the auxiliary suction system play its due role [1]. There are two types of feed mill pulverizer auxiliary suction system: 1 using a concentrated wind net to suck the wind mill pulverizer; 2 using an independent wind net to suck the wind hammer pulverizer. This paper mainly designs a reasonable auxiliary suction system by analyzing the problems existing in various forms of suction.
1 The problems of various forms of suction and the causes of them.
1.1 Problems with various forms of suction
1.1.1 Using a concentrated wind network to suck the hammer-type pulverizer
This form is more common in the feed production units of some small and medium-sized feed mills. The pulverizer uses a vibrating feeder to feed the air inlets that allow the effective airflow to enter; the conveying materials are semi-circular augers and suction hoods. The choices all help to block the bypass airflow from the conveyor. However, the main problem is: due to the design of the wind network, the high drag coefficient such as the blanking pit, the high air load and the high drag coefficient and the large load of the crusher are combined, and the air intake of the wind net mainly comes from the lower pit. The air volume from the pulverizer is very small, and even the positive pressure airflow generated by the rotation of the pulverizer hammer cannot be eliminated. The dust inside the machine overflows so much that the user has to use the sack to wrap the pulverizer inlet, so the effective airflow is substantially non-existent. The output of the pulverizer is naturally difficult to increase. In addition, the limitations of the unit installation and so on should be considered.
1.1.2 Using the independent wind network to absorb the wind from the hammer mill
This form is more common in some large and medium-sized feed mills, but in this form, the main problem is that there are many problems in production due to unreasonable design imperfections. When the system is used for a period of time, the bag of the combined dust collector is severely blocked, which greatly reduces the efficiency of the fan. The output of the crusher is reduced to about 70% of the rated output, or even lower. When the production is sprayed outside, the temperature inside the crusher is too high. The load of the motor increases; the dust in the workshop is diffused, and the working environment is bad, which seriously affects the normal production of the production; the bag (cylinder) of the dust collector is seriously blocked, the vibration cleaning is invalid, and only the manual cleaning is performed; the position of the suction port is improperly selected, and the air volume is small. Due to improper selection, the airflow drawn by the fan is mainly the bypass airflow flowing through the hoist; the upward airflow velocity at the exit of the auger is large, the material discharge is easily blocked, and the auger is often blocked. Therefore, a reasonable design must be made for this form of auxiliary suction.
1.2 The cause of the above problems
1 The suction cross section of the suction duct and the dust collector on the closed wind screw conveyor of the crusher is too small, the wind speed is too high, and the material is easy to take away; 2 because the material has a certain temperature and humidity after crushing, plus the choice of cloth fabric Poor and solenoid valve diameter is too small, the air volume for blowing is not enough, so that the dust collector after dust adsorption is difficult to clean; 3 the fan used is low in wind pressure, when the dust of the dust collector is seriously adsorbed and the resistance increases, And the sieve plate in the pulverizer has a small hole diameter, and the pulverized material is difficult to pass and the resistance of the sieve plate is increased due to partial clogging, the efficiency of the fan is greatly reduced, and the crusher has almost no effective negative pressure and suction; 4 The design of the closed-air screw conveyor is not reasonable, and the effect of the windshield or the windshield is not obvious, so that too much outside air enters, so that the air volume and wind pressure in the crusher are weakened, and the suction effect is greatly reduced [ 1].
2 The basis of the design of the pulverizer auxiliary suction system
1Understand the production scale and working system to determine the amount of material to be transported and working time; 2Understand the nature of the materials to be transported, so as to select the appropriate suction form and equipment according to different transport objects to meet the requirements of process production; 3 Understand the structure of the plant and the combination of the warehouse and the affiliated workshop. These are related to the selection, installation and arrangement of the auxiliary suction equipment; 4 skilled process flow and equipment layout to determine the number of suction pipes and their respective suction volumes, and the number of channels and channels required to transport the materials. The nature of the material, so that the network is reasonably combined, and the appropriate auxiliary suction wind speed is selected; 5 to understand the specifications and performance of the equipment used; 6 to define technical and economic indicators and environmental protection requirements; 7 to investigate the operational management conditions and technical measures Sex; 8 understand the vision development plan.
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