1.Structure
The belt bucket elevator is mainly composed of traction member, driving drum, driven drum, tension device, belt, hopper, feeding and unloading device, frame and driving device. The belt bucket elevator of Ningxia fertilizer plant is manufactured by DOUBRAVA company in Austria. It is a belt elevator with a design capacity of 110 t/h and a lifting height of 36 m. It has 156 hoppers. The driving drum is driven by a motor. The tension device of the driven roller adopts the form of the balance weight of the slide. 1.2 The problem of hopper cracking
There are a large number of wet urea blocks in the material granule urea discharged by the granulator, resulting in clogging of the material and inability to maintain normal production after the period operation of the fluidized granulator. The granulator must be cleaned for about 4 hours. During the treatment process, the material produced by the pre-system is circulated to the urine tank for temporary storage. After the belt bucket elevator is cleaned, the material in the urine tank is sent to the evaporation system. And then the material enter the graulator.
When the granulator is cleaning, the inspection hole of the shell of the belt bucket elevator is opened to inspect the hopper of the bucket elevator, and it is found that part of the hopper is cracked. If the cracked part is not dealt with in time, the hopper crack will be further expanded, and it will scratch the shell of the bucket elevator, resulting in the damage of the bucket elevator.
2. The analysis of the reasons of the belt bucket elevator
2.1 Increasing the load of the belt bucket elevator
After the granulator is cleaned, the stored urine enters into the evaporation system, and the normally produced urine and stored urine are enters into the granulator at the same time, that resulting in increased load on the belt bucket elevator. The increasing load will cause that the moving drum axis of the bucket elevator to move down, which is easy to cause the phenomenon of hopper cracking due to collision. At the same time, the leakage in the hopper material connection and discharge increases, leading to a higher material level at the bottom of the bucket elevator, and an increase in the amount of material scraped by the hopper. If it runs for a long time, it will also lead to fatigue and cracking of the hopper.
2.2 the belt deviation of belt bucket elevator
The belt deviation of the bucket elevator causes the hopper to swing. The large swing will lead to the collision between the hopper and the material interface, discharge port or the shell of the bucket elevator, resulting in the collision and cracking of the hopper.
The reasons of belt deviation:
a.The driven drum is not parallel to the driving drum.
b. The feeding is nonuniform that cause uneven force of the belt, which leads to the belt deviation.
1.The gap between the bucket and loading port and unloading port is too small.
The gap between bucket and loading is 20mm, and it between thebucket of belt bucket elevator and the unloading port is 8mm. Too small gap between the bucket and the loading and unloading ports will increase the probability of collision between the bucket and the loading and unloading ports. Excessive gap will increase the leakage of the bucket. In both cases, the bucket will crack.
2.Poor quality of the structure and the texture of the bucket. The structure of the hopper can be divided into shallow bucket, deep bucket and triangle bucket. The deep hopper is usually welded by steel plate or directly rammed.