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Equipment conveying system in cement batching plant

Writer:Admin   Time:19/03/05

     The conveying system in cement batching plant mainly includes aggregate conveying and powder conveying. Belt conveyor or hoist is often used for aggregate conveying, and screw conveyor and pneumatic conveyor are often used for cement and admixture conveying. Whether it is the transportation of aggregates or cement and admixtures, the generation of dust should be minimized. Its conveying speed and efficiency need to match the cycle time of the system.

    I. Belt Conveyor
    Belt conveyor is widely used in chemical industry, coal, metallurgy, mining and transportation departments. It is suitable for conveying various granular and powder materials with loose density of 0.5 t/m3~2.5 t/m3. It can also be used for conveying articles. Horizontal belt conveyor and inclined belt conveyor are used in concrete batching plant to realize horizontal and inclined transportation of sand and gravel. In practice, inclined belt conveyors often use various shapes of conveyor belts, such as flat belt, herringbone belt, skirt belt and so on. Its working dip can range from 2 ~60.
    II. Hoist
    The hoist is composed of hoist 1, motor 2, guide rail and support 3, hoist bucket 4 and wire rope. Hoist is the most suitable hoisting equipment for conveying aggregate to storage device of batch plant machine in narrow construction site. Hoist is used in concrete mixing station. It covers a small area, but it has a large lifting power. The effective volume of lifting bucket is at least 1.6 times that of stirring discharging capacity. There are two main types of unloading of sand hopper: tipping type and bottom opening type. Both of them use brake hoist and pull through pulley group and wire rope to achieve the purpose of lifting hopper. Double wire rope transmission is often used in large and medium concrete batching plants.
    In small concrete batching plant, single-rope transmission with suspension or with pulley guide on hopper is usually used directly. The hoist is driven by one motor and two motors in a large concrete batching plant. The motor shaft is forced to synchronize. Hoist lifting speed is mostly 0.4 m/s~0.5 m/s. In order to improve the conveying productivity of hoppers, variable frequency speed regulation or two-speed motor can also be used, so that a variety of working modes can be selected: slow start-fast lifting, fast drop-slow positioning.
    III. Screw Conveyor
    It is a conveyor that conveys objects by means of rotating spiral blades or by means of a material trough with an inner spiral surface that can rotate itself. The powder material used in concrete mixing station (building) is conveyed by screw conveyor. By controlling the rotation and stop of screw blade, the powder material feeding can be controlled. The conveying must be carried out in a completely sealed chamber to avoid polluting the environment and dampness and agglomeration of conveying materials. TUBE screw conveyor is generally used to convey cement and admixtures. Pipe screw conveyor can convey materials horizontally, vertically and obliquely. The conveying productivity of powdery materials is related to the screw pitch and rotating speed, as well as the bulk density and filling degree of conveying materials. In order to improve the conveying capacity, the variable pitch conveying blade is adopted. The lower feeding section has smaller pitch than the conveying section, and the filling volume is larger in the feeding section. With the increase of the pitch, the filling volume decreases, which can prevent the backflow of high flowing powder material during conveying.
    Generally, the conveying screw works at a certain inclination angle, the inclination angle can reach 45 degrees, and the larger inclination angle can reach 60 degrees. Different length screw conveyors can be obtained by adding or subtracting standard sections. The maximum length of each screw should not exceed 14m. The longer transmission distance can be realized by screw relay. The longer spiral pipe requires intermediate support and lubricable coupling for installation. The conveying screw used for conveying cement and admixture has a diameter of 160 mm~325 mm, a conveying productivity of 20 t/h~100 t/h, and a speed range of 90 r/min~300 r/min. When the screw conveyor works, the loading condition is related to the blanking condition and the conveying material condition. The filling coefficient in the screw pipe is about 30%~50%.
    Pneumatic conveying
    Pneumatic conveying is mainly used to convey powder materials. Cement and admixtures are usually transported by bulk cement trucks. The conveying system of bulk cement trucks is used for transportation. The powder materials are blown into suspension state by compressed air during transportation. Mixed gas is transported to the tank along the pipeline. The dust collector on the warehouse roof collects the dust from the overflowing gas in the tank. When using bagged cement, a pneumatic suction device for bagged cement is needed for pneumatic conveying.