On the requirements of grain storage for granary design
Ticket Lin? Zhu Tongshun Li Zhao Zhao Yingjie Li Jianfeng
(Henan University of Technology 450052)
On the basis of summarizing many years' experience in the design and construction of grain depots, this paper expounds the requirements of safe grain storage for granary structure, door and window openings, grain storage performance and grain storage facilities from the perspective of storage technology, and puts forward corresponding suggestions or improvement measures for the problems existing in granary design.
Grain storage; Storage technology; Granary design; barn
Building a granary that meets the requirements of grain storage is the first condition for doing a good job in grain storage. It should have the following properties: first, it meets the needs of safe grain storage from the structure of the granary, has good grain storage performance, maintains the quality of grain storage, and prevents the grain in the granary from mildew and moth-eaten; The second link of grain import and export is mechanized and automated, and the grain import and export is smooth and fast; Third, the supporting facilities for grain storage are perfect, which can monitor the changes of grain situation at any time and have various means to ensure the safety of grain storage.
1 Importance of storage technology to grain storage safety
1. 1 Relationship between storage technology and civil engineering design
Warehouse workers should put forward the requirements of storage technology for warehouse structure before opening the warehouse, and the civil design of the warehouse must meet the requirements of storage technology. Both parties should cooperate with each other to complete the design and construction of the warehouse building. Warehousing personnel should participate in the whole process of opening positions and improve them in time when problems are found.
1.2 barn construction must meet the needs of grain storage.
Granary is used to store grain, and the rationality of storage technology has an extremely important impact on the safety of grain storage. In the era of planned economy, due to the division of system and compartmentalization, and the separate management of infrastructure and storage and transportation, the design and storage technology are out of touch, which makes the warehouse lack the necessary storage facilities and processing methods. As a result, the new warehouse was "rebuilt after construction". Second, there is a lack of food storage facilities. For example, in the silo group constructed by 18 mechanized backbone warehouse, bad grain accidents will occur during grain storage in winter, which will make some silo groups idle for a long time and cause waste of storage capacity. Therefore, it is of great significance to strengthen the research on grain storage technology and supporting facilities for popularizing grain deep storage technology.
2. Requirements of safe grain storage on granary structure
2. 1 The barn must be durable.
The granary is different from other buildings, besides the loads such as wind load, snow load and earthquake, it also bears considerable grain lateral pressure, especially considering the influence of different grain types, different stacking methods and different grain loading heights on the barn wall to prevent the wall from cracking; It is also necessary to consider the vertical pressure of different grain crops and different grain loading heights on the ground to prevent the ground from sinking.
Because of different kinds of grains, the scattering characteristics of wheat and rice are different, and the same grain stacking height requires different wall strength. When the same variety is stacked in different ways, the force of grain on the barn wall is also different. Under normal circumstances, it is not advocated that the grain in the barn is overloaded. If the bulk granary is overloaded, it can be loaded on the grain surface at the height of the grain loading line from the silo wall 1m according to the trapezoid. Because the wall of the packaging bin can't bear the lateral pressure, it can't be directly used as a bulk bin. If bulk grain is to be packaged, it can only be stacked by parcel, otherwise there will be problems. For example, on July 6th, 1999, a flour mill in a county in Jiangsu was informed that the packaging warehouse was directly used as a bulk warehouse, and the warehouse collapsed when the grain was not full. The dynamic load of flowing grain is usually several times its static load. For gravity silos, attention should also be paid to the influence of unloading load on the facilities in the cylinder and silo. Asymmetric unloading or sudden collapse of arch grain will cause cracks in the cylinder and damage the facilities in the cylinder.
The grain loading height of the early granary was low, so the stress of the granary was calculated according to the retaining wall formula. The grain loading height of the existing granary has increased. Although the thickness of the wall may not have increased, a lot of steel bars and cement are used, and multiple ring beams are added in the wall, which greatly increases the strength of the wall. At this time, the wall strength can not be calculated simply by retaining wall formula, but by lateral force transfer and bent structure.
There shall be no potholes, rat holes and ant holes at the top of the underground warehouse, which shall be compacted by layers with clay. There can be no tall trees within the arch foot 10 meter. The slope protection of underground bunker should be kept as natural as possible, and turf should be planted to prevent landslide and rain from overflowing the hole.
2.2 Settings of doors, windows and holes of the warehouse.
The setting of doors, windows and holes of granary should consider the convenience of grain access technology and daily management, the height and width of granary doors should consider the access of grain storage machinery, and whether the size, number and opening mode of granary doors meet the needs of ventilation and replenishment. The ground outside the warehouse should be hardened to withstand the walking of fans and grain import and export machinery.
2.2. 1 The warehouse should have fewer windows, the size of which should meet the replenishment needs.
Early barn windows were mainly used for lighting and natural ventilation. Existing barns were equipped with lighting, air ducts and fans, and windows were mainly used for ventilation, dust removal or grain replenishment. If every room in the warehouse is designed with windows, too many windows will directly affect the heat insulation and air tightness of the warehouse. It is suggested that the number of windows be halved. Because of the rain above the warehouse door, it is inconvenient for the keeper to switch, so there is no window. Window sash should be opened horizontally or upwards with a single sash, and double casement windows or sliding windows should not be used; The window size should meet the needs of mechanical grain replenishment outside the warehouse.
2.2.2 Warehouse doors should be few to avoid sunlight.
The orientation and number of warehouse doors should not only consider the speed and convenience of grain entry and exit, but also consider the safety of grain storage, as well as the convenience of road planning and loading and unloading of special railway lines in the warehouse.
In production, grain is usually put back into the side wall in the warehouse, and there is an air duct on the floor, so the 10 ~ 15m conveyor can't turn around in the warehouse. Reducing the number of warehouse doors can not only reduce the construction investment, but also improve the air tightness of the warehouse. Therefore, it is suggested that the warehouse door of small-span storage warehouse should be designed on one side to avoid direct sunlight; Doors are set on both sides of the long-span warehouse, which are asymmetrically arranged. Among them, the main warehouse door is designed to be large, which is conducive to mechanical access, while other warehouse doors are made to be small, which is conducive to warehouse door sealing.
2.2.3 Setting of grain inspection door or manhole in granary.
Because instrument detection can't completely replace artificial sensory detection, warehouse keepers often enter the warehouse to check the grain situation, and the setting of small doors or manholes for grain situation inspection in the warehouse should be convenient for warehouse keepers to enter and exit.
Flat warehouse and other shallow warehouse types, each warehouse (room) only needs one grain inspection door. Setting a vertical ladder at the door is not conducive to the keeper to carry things up and down the grain pile. It is suggested that the grain inspection door should be located on the north side of the warehouse or at the gable, and an inclined ladder should be set outside the warehouse to facilitate the storekeeper to carry things up and down. Some grain depots are equipped with better cabins on the platform, which can be used to store grain storage materials, cards, grain search instruments and so on.
For deep grain silo type, manhole must be set at the top of shallow silo and silo, and its position should be close to cornice, and ladder should be set inside the barrel wall to facilitate the storage personnel to get up and down. Manholes should also be set at the bottom of tall silos for empty warehouse cleaning and equipment maintenance. The manhole structure should not only be convenient for the keeper to open, but also be convenient for sealing when storing grain. Pedestrian trestle should be set at the eaves between shallow silos to facilitate the guards to walk.
The manhole in the early shallow warehouse was located in the center of the warehouse top, which was not conducive to grain inspection. Now most grain depots have been transformed, and an air outlet has been changed into an air outlet for both air and people. In other words, some barrel depots have used hanging baskets for people to get up and down. Because the hanging basket will rotate when it goes up and down, it is not safe, and it is basically not used now.
2.2.4 Setting of grain retaining door
Bulk grain exerts great lateral pressure on the warehouse wall. Generally, the warehouse door of flat-bottomed warehouse does not directly bear the lateral pressure of grain, but is borne by the grain retaining plate (door). The lower part of the grain baffle (door) of the granary is provided with a grain unloading port for unloading grain before the grain baffle (door) is opened. There are many forms of grain baffle (door). Although it is inconvenient to place grain baffle, it is convenient to unload grain. The grain blocking door is easy to open and close, but after the grain is unloaded at the grain unloading port, some grain still blocks the grain blocking door, which can only be solved by grain suction machine or manual grain unloading, which is not as convenient as the grain blocking plate. Grain-blocking doors should be adopted for shallow round warehouses, and grain-blocking doors are also recommended for bungalow warehouses. If the grain baffle is selected, there should be a gap in the U-shaped fixing groove of the wall to facilitate the placement and disassembly of the grain baffle. When using the V-shaped grain baffle, there should be a top cover above the inner wall of the doorway, otherwise a triangular deep hole will be formed at the grain baffle, and the light in the warehouse will be dim, which will cause security risks for the keeper to count the grain.
2.3 Grain storage performance of granary
Grain is not only a heat-sensitive substance, but also a highly hygroscopic substance. The high temperature and high humidity environment will easily lead to the decline of grain quality, which will lead to the fever and mildew of some or even the whole grain in the grain pile. Therefore, the granary is required to have good heat insulation, moisture resistance and sealing performance.
2.3. 1 Moisture-proof and leak-proof performance
The leakage or moisture regain of the roof, wall, floor and air duct of the granary is easy to cause the grain to be damp and moldy, so it is necessary to strengthen the leak-proof and moisture-proof treatment of these parts to meet the needs of safe storage of grain.
Commonly used waterproof materials include polymer modified asphalt coiled material (coating), synthetic polymer waterproof coiled material (coating), fine stone waterproof concrete, asphalt-based waterproof coating, rigid waterproof layer, flat tile and so on. In the arrangement of moisture-proof layer, it is necessary to make water vapor "difficult to enter and easy to exit" on the channel, which is generally set at the high temperature side of the insulation layer to avoid moisture condensation inside the insulation material and reduce the insulation effect. There are many grains in the shallow silo, so it is not easy to reverse the warehouse. Pay more attention to the leak-proof and moisture-proof of the warehouse body. For granaries, moistureproof and seepage prevention are equally important, especially the unloading corridor and settlement joints of shallow silos should be treated according to seepage prevention standards.
There should be a rain cover on the outside of the hole of the exhaust fan at the upper part of the barn to avoid rainwater infiltration, and a sealed door on the inside to avoid air leakage during fumigation.
heat-proof quality
The enclosure structure of the barn, especially the roof of the barn, is the main way for external heat to enter the barn. In order to keep the grain stored in the granary at low temperature, it is necessary to improve the heat insulation effect of the granary.
There are two methods for thermal insulation of granary, static method and dynamic method, and the static method is often used in production. (1) add solid insulation layer on the roof, and improve the thermal insulation performance of the structure by using the thermal resistance and material heat storage of the roof material layer, thus reducing the average temperature and temperature fluctuation range of the inner surface of the roof in summer; ⑵ Add a ventilation layer on the roof, and use the ventilation layer to block the sun, so that the roof can be converted into secondary heat transfer, and the sun can not directly radiate to the envelope. At the same time, under the action of wind pressure, natural ventilation takes away the heat in the interlayer, reducing the influence of hot air outside the warehouse on the roof and reducing the temperature inside the warehouse; (3) A ceiling made of thermal insulation material is used in the warehouse to isolate the heat seeping into the roof from the ceiling, meanwhile, an exhaust fan is installed on the gable, and the accumulated heat is continuously discharged out of the warehouse from the triangle under the roof by low-temperature ventilation at night, so as to improve the thermal insulation effect of the ceiling; (4) When the roof is whitened, laying tin foil paper or spraying paint with high reflection coefficient can reflect the radiant heat of sunlight, which can reduce the temperature of the warehouse by 2 ~ 5℃, such as Meidun reflective paint and special thermal insulation paint for Liangbao, but the thermal insulation effect is closely related to the cleanliness of the coating, and brushing 1 ~ 2mm gypsum slurry is also effective, economical, simple, sun-resistant and erosion-resistant; 5] Cai Gang roof can be insulated by spraying Cai Gang gusset plate, rock wool, composite polystyrene board, polyurethane, etc. When installing profiled steel plate, attention should be paid to the insulation and airtight treatment of the butt joint; [6] Increase the insulation layer on the warehouse wall, and leave an interval layer of 10cm outside the concrete wall of shallow warehouse, with the thickness of aerated concrete block of 15cm, or spray polyurethane 30-50 mm thick on the outer wall, cover it with barbed wire, and then brush the mortar layer for protection. The flat warehouse can be directly filled with polystyrene board for insulation in the hollow rib wall; (7) Climbing plants or plants with higher crowns can be planted in places that do not affect the construction and work of warehouses, such as the warehouses directly under Kunming and Liuzhou National Warehouse, so as to reduce the direct sunlight to the warehouses.
In order to improve the thermal insulation capacity of the warehouse, materials with relatively low thermal conductivity should be selected, such as expanded perlite, glass wool, foamed polyurethane and polystyrene foam. And we should pay attention to the arrangement of material layers, and it is best to use a ceiling composed of multiple layers of materials, so as to give full play to the characteristics of each layer of materials. If the inner side of composite structure is made of heavy material with proper thickness or sandwiched with light material, its thermal stability can be further improved. Using new energy-saving cold light source instead of incandescent lamp lighting can also reduce the temperature rise in the warehouse.
2.3.3 The warehouse should be closed and ventilated.
The ventilation and sealing performance of granary is very important for the safe storage of grain. Open doors and windows, and promote gas exchange of grain piles through natural or forced ventilation, cool down and dissipate moisture, and prevent stored grain from being heated and moldy.
Ventilation and cooling is a frequent and arduous task in the daily management of warehouses, especially in the management of low-temperature grain storage, it is often necessary to turn on ventilation and cooling at midnight. The automatic opening and closing of the barn window is a key step to realize the automatic operation of reducing the barn temperature, which is of great significance to delay the rising speed of grain temperature, improve work efficiency and reduce labor intensity. And the transformation investment is not big, but the effect is obvious. Many existing grain depots have been reformed.
In order to realize the automatic control of grain stack ventilation, it is necessary to increase the automatic control device of air inlet and fixed ventilator. At present, only a few granaries have realized this function, but the limited ventilation operation and high investment cost limit its popularization in most granaries.
The granary has good air tightness, which is beneficial to grain storage, controlled atmosphere storage or fumigation and pest control. It can not only reduce the contact between grain and outside air, avoid the influence of outside temperature and humidity and insect infection, but also keep the stability of grain temperature and humidity in the granary. It can also maintain the effective concentration and proportion of gas in the warehouse when fumigating with chemical agents, and obtain good insecticidal effect.
The requirements for the air tightness of fumigation in existing warehouses in China are: check the air tightness of doors, windows and holes of warehouses after sealing, the half-life of closing positions at 500Pa shall not be less than 40s, and the shallow warehouses shall not be less than 1min. This is the temporary standard determined by 1998 new warehouse construction acceptance. There are also some problems in the fumigation process, such as the difficulty in maintaining toxic gases, the need for supplementary dosing and poor insecticidal effect, which should not be used as the basis for formulating relevant new standards. With the improvement of the design level of the new warehouse, the air tightness of the new warehouse has been obviously improved. It is suggested that the air tightness standard of warehouse should be improved appropriately. After the doors and windows of the warehouse are sealed, the half-life of the warehouse under the pressure of 500Pa is not less than 100 ~ 150 s, and the shallow warehouse is not less than 2 ~ 3 min. In the recent construction of two batches of 20 billion Jin warehouses, most warehouses have reached this standard after taking sealing measures. At the same dosage, one dose can achieve good insecticidal effect, which is conducive to the scientific use of phosphine and delay the emergence of drug resistance.
2.3.4 The warehouse should have facilities for preventing rats and birds.
During the storage of grain, rats and birds should be prevented from being hurt. Mice and birds not only consume a lot of food, but also excrete feces that will pollute food. In order to prevent rats and birds, the ground, walls, doors and windows of the barn must be solid and dense, and holes are not allowed. The warehouse must be equipped with bird-proof window nets (mesh ≤ 1cm) and rat-proof door panels (height 0.6 ~ 0.9 m). In order to improve the air tightness of the warehouse door, it is sometimes necessary to embed plastic grooved pipes at the inner side of the door frame 10cm, so it is required to set the position where the rat board is placed at the inner side of the warehouse door 15cm.
3. Requirements of safe grain storage for warehouse supporting equipment
The application case of 18 mechanized backbone silo proves that it is not enough to have a warehouse with good structural performance, but also to be equipped with perfect grain storage facilities to improve the ability to inspect and deal with emergencies in order to ensure the safety of grain storage. The main grain storage facilities are:
3. 1 grain monitoring system
Grain monitoring system is a necessary facility for long-term storage of grain piles in grain depots. The detected values of temperature and moisture of grain pile are the important basis and information source for keepers to understand the changing trend of grain situation in deep grain layer and analyze the grain situation, so as to find problems early and take corresponding technical measures.
At present, most grain depots are equipped with grain condition monitoring and control systems, but their functions, temperature and humidity parameter detection and data collection, grain condition analysis and control, compatibility and data sharing of different detection systems, and component sealing need to be improved. In recent years, several sets of intelligent ventilation control systems for grain piles have been developed in the integrated demonstration project of new technology and equipment optimization for grain storage and transportation, which will further improve the grain situation control function.
3.2 Ventilation and cooling system
Ventilation and cooling system is an essential facility for all kinds of granaries, which has the functions of balancing grain temperature, effectively preventing moisture diffusion, heating and mildew of grain piles, and improving grain storage performance. It is also the basis for the application of circulating fumigation and grain cooler. When selecting or arranging, you should pay attention to:
3.2. 1 principle of air duct selection and layout: when selecting air ducts, the influence of warehouse use, warehouse access operation form and ventilation duct ratio must be considered, and only one air duct form can be arranged in a warehouse (room). Ducts should be selected according to the requirements of uniform air supply and effective ventilation. The air duct technology should be simple and symmetrical, with large air outlet area and small ventilation resistance, which is convenient for construction or installation, operation and management. The strength of perforated plate of air duct should be able to bear the load of grain or equipment, and the opening rate of sieve plate should be ≥25%.
3.2.2 Ventilation equipment shall be safe, reliable and easy to operate. The fan pressure should be able to overcome the total resistance of the ventilation system, and the fan air volume should meet the needs of different ventilation purposes such as ventilation, cooling, precipitation and air conditioning.
3.2.3 Axial flow fans can be used to reduce the warehouse temperature, and generally 2 ~ 4 fans are used in each warehouse (room). It is recommended to install the fan as high as possible. When ventilating, open the north window and start the exhaust fan on the south wall, or open the innermost window of the barn and start the exhaust fan on the single-sided gable wall, so that the cold air can take away the high temperature in the triangle under the roof to the maximum extent.
3.2.4 Centrifugal fan or axial fan can be used to reduce the grain temperature. Axial flow fan has the characteristics of large air volume, small wind pressure, low energy consumption and less grain water loss, but it has a long ventilation time, and is suitable for systems with small ventilation resistance and grain depots with long low temperature seasons. During ventilation, open the air inlet of the air duct, close the doors and windows of the granary, and open multiple axial fans to reduce the grain temperature. Centrifugal fan has the characteristics of large air volume and high wind pressure, and it has the characteristics of fast cooling and short ventilation time, but it consumes a lot of energy and loses a lot of grain moisture, so it is suitable for systems with large ventilation resistance and occasions where ventilation takes time. When ventilating, open all doors and windows of the warehouse and turn on the fan for ventilation, so that the waste gas can be discharged from the warehouse smoothly.
It is suggested that the air inlet of the one-side ventilated granary should be located in the north side of the granary, where the temperature is low, which is conducive to the cooling of grain piles, grain cooling operations and fumigation operations.
3.2.5 The structure of the air inlet shall meet the requirements of convenient opening and closing of the air inlet cover plate, convenient docking with equipment and good heat insulation and air tightness of the air inlet. For air inlets with poor heat insulation and air tightness and troublesome opening, round air inlets can be adopted or changed into fastening forms such as double hinged doors and butterfly nuts, buckles, revolving doors or pull rod springs, and the rubber strips are thickened to increase air inlet heat insulation.
3.3 Circulating fumigation system
Circulating fumigation system is an essential facility for grain storage in grain depots, especially in temperate southern grain depots. It can make the toxic gas diffuse rapidly and evenly in the grain depot, reduce the labor intensity of pesticide application, reduce the contact time of toxic gas, and achieve good insecticidal effect. Attention should be paid to when applying:
3.3. 1 In production, fumigation pipes are often combined with the ventilation system in the warehouse, and a ventilation-fumigation system is designed, and the ventilation channel is used as a diffuser, so that toxic gases are evenly distributed in the grain pile, which is conducive to improving the fumigation effect and reducing the investment in fumigation equipment.
3.3.2 Phosphine is a flammable and explosive gas. In order to prevent phosphine explosion, the maximum linear velocity of fan blades should not be greater than 40m/s, and the lower explosive concentration of phosphine is 26g/m3. Therefore, the concentration of toxic gas entering the fan should not exceed 1.7%.
3.3.3 In the book "Ventilation of Subtropical Grains" compiled by FAO, the recommended ventilation volume for circulating fumigation is q= 1.5m3/h? T, but for phosphine circulating fumigation, the unit ventilation rate of the warehouse is q≤0.5m3/h? T, q≤0.3m 3/h for tall silos? t .
3.3.4 In order to prevent phosphine gas explosion and excessive air resistance, the wind speed in the circulating pipe should generally be limited to 15m/s, and the diameter of the main circulating pipe should be greater than 100 mm.. 1998. In the construction of a new warehouse, it is suggested that the inner diameter of the main circulating pipe should be φ 1φ65mm, and the inner diameter of the air inlet circulating interface should be.
3.3.5 In cyclic fumigation, there are three gas production methods recommended by the corresponding specifications or currently used in production, namely, gas cylinder filling method, phosphine generator outside the warehouse method and dynamic moisture decomposition method. Experiments and production applications show that the insecticidal effect is related to fumigation concentration and has nothing to do with gas production mode, but fumigation cost is closely related to gas production mode. Considering the principle of "safety, economy, effectiveness and practicality", the "dynamic deliquescence" method is simple and safe to operate and has the lowest cost, so it has been widely popularized and applied.
3.4 Grain cooling system
The grain cooling system can be used for emergency treatment of hot grains, prevention of condensation, storage of high-moisture grains, inhibition of insects and molds, and maintenance of quality. Its application features are:
3.4. 1 Directly cooling the grain pile has the advantages of fast cooling speed of the grain pile, good thermal insulation of the bulk grain pile, long interval of re-cooling, and no need to build a special low-temperature warehouse.
3.4.2 timely cooling, to stop the tide grain fever mildew, prolong the storage period, to win time for drying, ventilation and precipitation.
3.4.3 Reasonable operation is the key to determine the benefit of valley cooling. First, we should pay attention to choose a reasonable cooling and ventilation opportunity, and try not to start the machine under high temperature and high humidity. Second, it is necessary to operate the equipment correctly and adjust the process parameters to make the grain cooler work in an economic operation state and solve the problems of excessive cooling power consumption.
3.4.4 The grain cooler is suitable for storing grains with slightly higher moisture content or sensitive to temperature, such as grain depots that process and export high-quality rice and handle hot grains in no low-temperature season or summer. Someone has made an economic comparison, and the power consumption of cooling grain piles with grain pile cooler is lower than the economic loss caused by water reduction.
3.5 slow grading and anti-crushing device
When the grain with poor quality or high waist explosion rate is put into the warehouse by machinery, especially when it is concentrated in a tall granary with a large grain gap, it is easy to form automatic grading or serious crushing of grain, so measures should be taken to slow down grading or prevent crushing.
The most effective measure to slow down impurity classification is to actively clean up and improve the quality of stored grain. However, screening to remove impurities will reduce the quantity of grain, and some grain depots are unwilling to clean up when the weight loss cannot be compensated by policies or prices. The passive measures are to add distributors, grain distribution umbrellas and other devices at the grain inlet, or to adopt the method of central tube feeding and multi-point feeding, but some devices can not achieve a good effect of slowing down grading.
The most effective link to reduce grain breakage should be to control the drying process parameters, that is, to choose appropriate hot air temperature and precipitation rate, too high air temperature and too fast precipitation are easy to cause grain cracking; The second is to control the mechanical crushing of grain in the process of lifting and conveying; Adding chute, telescopic tube or deflector in the decompression tube of grain inlet of deep silo can slow down the falling speed of grain in silo and control the crushing problem of grain in silo. According to the production and use situation, the double funnel overflow and guide plate have better effect of slowing down the crushing.
3.6 granary should consider the mechanized operation of grain import and export.
Grain depots are large in number and volume, and sometimes they need to be turned around quickly. When designing the granary, we must consider the mechanization of entering and leaving the grain and turning the granary. This is especially important for port transit warehouses, raw material warehouses of processing plants, silos with various purposes and large-capacity shallow silos. However, it is restricted by local economic development, traffic conditions, modes of transportation, labor price and other factors.
When determining the grain storage, it is necessary to comprehensively consider the warehouse structure and the facilities in the warehouse, such as the size and opening mode of the doors and windows of the warehouse, the replenishment of the grain piles over 6 meters, the layout of the air duct in the warehouse and the mechanical movement of the grain storage, etc., and then determine the grain storage, and select the supporting mechanical equipment.
The cost of bungalow warehouse is low, but the operation of grain storage is troublesome, time-consuming and costly. It belongs to the warehouse type with a low proportion in developed countries. Due to the limitation of national strength, there are many existing bungalow warehouses in China, and the number of bungalow warehouses should be gradually reduced in the future construction. At present, China's bungalow warehouses generally use mobile belt conveyors to feed grain, but also use grain filling machines or grain suction machines to fill the warehouse from the window. Generally speaking, grain is transported by a combination of a grain scraper and a mobile conveyor, or by hand.
Silos are expensive, but grains can get in and out of silos quickly. Silos are usually equipped with working towers, which are equipped with lifting, cleaning, weighing, dust removal and other equipment, and horizontal conveyors are installed at the top and bottom of silos to complete the entry and exit of grain.
The shallow silo belongs to the type of transit storage silo, and its cost and operation in and out of the silo are between the bungalow silo and the silo, while the storage stability of the large grain pile is better than the two. The grain feeding of shallow silo is completed by elevator and silo top conveyor; When leaving the warehouse, most of the grain is taken away by the conveyor at the bottom of the warehouse, and the remaining 20 ~ 30% of the grain is completed by loaders, grain cleaners, grain harrows and grain suction machines. At this time, the unloading speed may not reach the designed output and required time of the equipment.
At present, the most common problems reflected by shallow silo are: shallow silo is used as reserve silo, but the grain import and export process is designed according to the mode of transit silo, and the machinery and equipment are idle for a long time, and the maintenance cost is high.
In short, the barn design should combine all kinds of grain storage technology and "bulk" grain technology to ensure that the grain quantity is true and the quality is good, and it can be used when the country is in urgent need.