Lime powder silos mostly adopt floor-to-ceiling construction, with a concrete structure bottom plate located underground, with a downward inclination angle or a masonry-constructed material-guiding slope. The stored materials are in direct contact with the bottom plate in the warehouse, and their moisture content is easily affected by the quality of the civil construction and the dryness of the bottom plate during the initial feeding. Especially for powdery materials, the specific surface area is large, and it is easy to absorb moisture, and it will form a solid mass in severe cases. At the same time, the bottom material is accumulated for a long time, and the density will gradually increase with time and the nature of the incoming material. The material on the upper surface of the bottom plate is agglomerated and cannot flow, causing the fluidization device to be unable to breathe and block the air path. Agglomeration at the discharge nozzle, unable to flow, blocking the material path. When the material is damp, it is prone to arching and the pneumatic system fails. Reduce the active material belt of the material, and the material surface forms a relatively steep discharge funnel, which causes the accumulation of materials on the silo wall.
Analysis of the reason why the bottom material of lime powder silo is easy to be damp
1. The bottom of the lime powder silo is a cast-in-place concrete structure, the upper part of the bottom is plastered with cement, and some internal fillings are also concrete structures. During the construction of the silo floor, the cast-in-place concrete will bring in a large amount of free water. When the cement is hydrated, the excess water remains in the concrete to form blisters or pores after evaporation. These pores are connected to each other to form an open capillary bleeding channel, thus reducing the permeability of the concrete structure and increasing the water permeability. When the bottom plate cannot be completely air-dried, the materials put into the silo will absorb water and become damp.
2. There are a large number of capillary pores in the concrete, and the siphon effect produced will cause the water from the bottom plate to penetrate into the bottom plate, and it will also cause the material in direct contact with the bottom plate to be damp.
3. Failure to vibrate or vibrate in time during the construction process will cause the concrete to be weak and easily form transverse cracks or powder, resulting in honeycombs and cavities, resulting in water seepage at the bottom. Improper mortar construction process, over-wet or over-dried base treatment, insufficient or over-watering will cause shrinkage cracks and leakage, and inevitable holes and cracks during the construction process will also enhance the infiltration of groundwater vapor.
4. The filling material in the masonry warehouse generally forms a closed space after the warehouse body is dropped. After the water brought in during the masonry evaporates, water droplets will form when it meets the top steel plate, and then fall on the bottom plate after gathering. Form a "rain phenomenon", repeated cycles, and can not be discharged outside the warehouse. The environment in the silo does not create conditions for the concrete to dry, resulting in the bottom plate not being really dry.
5. Before the silo enters the material, the bottom plate must have a certain air-drying time to ensure that the material will not be damp, especially in winter construction, the air-drying time should be longer. Because the management awareness is not in place or the feeding schedule is advanced, enough drying time is not reserved.
According to the analysis, the infiltration of free water and underground water vapor into the silo can be effectively reduced to prevent the material at the bottom of the silo from being damp. At the same time, attention should be paid to the characteristics and storage time of the initial input materials. During the trial operation phase of the steel silo, necessary measures should be taken to prevent the initial input material backlog and compaction.
Measures to prevent the material at the bottom of the lime powder silo from being damp
In order to prevent the material at the bottom of the large silo from being damp, it is necessary to isolate the stored materials from the concrete bottom plate, and cut off the free water and vapor exchange channels between the materials and the bottom plate. At present, the silo can adopt measures such as laying half-open steel pipes in the trough, laying steel plates on the upper surface of the bottom plate, attaching the inner lining board, and painting the glass fiber reinforced plastic film. After a comprehensive comparison of several measures, it is found that the epoxy glass fiber reinforced plastic coating method has the advantages of complete isolation, firm and durable bonding, and no cracks in the cured layer occurred during use, which caused the material in the warehouse to be damp.
The epoxy glass fiber reinforced plastic coating film used in the lime silo is composed of a base coat and a top coat. The primer layer has high permeability. It can penetrate into the concrete and cement mortar through the fine cracks and capillaries of the concrete or mortar base layer for 3~10 mm. After being consolidated, it is bonded to the base layer as a whole to form an impervious, water-repellent and waterproof Floor. The epoxy surface coating has high compactness. It forms a complete FRP film on the basis of the primer. It has high hardness, abrasion resistance and low friction coefficient. The epoxy FRP coating is applied and the finished product effect.
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