State regulations which enterprises must be equipped with cold storage

Cold storage (cold storage), the use of cooling facilities to create suitable humidity and low temperature conditions of the warehouse. Also known as cold storage. Is the processing, storage of agricultural and livestock products. Can get rid of the influence of climate, prolong the storage of agricultural and livestock products freshness period, in order to regulate the market supply.　The use of cold storage: cold storage is the method of artificial refrigeration so that the fixed space to achieve the required temperature to facilitate the storage of goods in the building. Cold storage can be widely used in food factories, dairy factories, pharmaceutical factories, chemical factories, fruit and vegetable warehouses, egg warehouses, hotels, hotels, supermarkets, hospitals, blood stations, troops, laboratories and so on.　　Cold storage is mainly used for constant temperature storage of food, dairy products, meat, aquatic products, poultry, fruits and vegetables, cold beverages, flowers, plants, tea, medicines, chemical raw materials, electronic instrumentation and so on.　　Overview Ice cellar in northern China is the primary stage of cold storage. Beijing's Beihai ice cellar is said to have been built in the Ming Dynasty, has been used for four or five hundred years. 19th century, the world's first mechanical refrigeration device, the use of artificial refrigeration equipment to control the success of low temperature. From then on, cold storage building in many countries rapid development, agricultural and livestock products from harvesting, processing to the sale of goods in all aspects of the realization of cold storage. China's construction of modern cold storage began in the early 20th century. At present, large and medium-sized cities have a considerable number of cold storage, and its capacity is increasing. In addition, due to the development of gas-conditioned storage technology, there is also a gas-conditioned cold storage. Can create a low-pressure, high humidity environment of the decompression of the cold storage is also being studied and designed.　Classification According to the different nature of use, can be divided into production cold storage, distribution of cold storage and life service cold storage 3 categories. Productive cold storage is an important part of food processing enterprises, generally built in the area of concentrated sources of goods. Fish, meat, poultry, eggs, fruits, vegetables and other perishable foods, after appropriate processing, sent to the cold storage for cold processing, and then transported to the consumer area for distribution. It is characterized by cold processing capacity, storage items zero into the whole out. Distribution of cold storage is generally built in large cities or water, land transportation hubs and densely populated industrial and mining areas, for market supply, transportation transit and storage of food. It is characterized by large refrigerated capacity, freezing capacity is small, suitable for a variety of food storage. Life service cold storage is for the transfer of life needs and temporary storage of food, which is characterized by small storage capacity, short storage period, more varieties, stacking rate is low.　Site and building design Cold storage should be built in convenient transportation, water, electricity supply from a reliable source of place, the site should be surrounded by good environmental health conditions, as far as possible to avoid the harmful gases of industrial and mining enterprises, smoke, dust, as well as from infectious disease hospitals and other sources of pollution. Meat, fish and other processing plants such as cold storage should be arranged in urban settlements in the summer wind direction of the minimum frequency of the upwind side, located near the origin or distribution of goods in a convenient place. The building generally consists of cold processing and cold storage building, cold processing auxiliary building, transportation facilities, management and living room building and machine room ice room building and so on. Cold processing and cold storage buildings collectively referred to as "cold room", including the temperature at 0 ℃ cooling room, the temperature at -23 ~ -30 ℃ of the freezing room, the temperature at -12 ~ -20 ℃ of the cold storage room, as well as the temperature at -4 ~ -10 ℃ of the ice storage room. The plane layout of the cold storage should make the process flow reasonable, short routes, not cross, high and low temperature zoning clear, minimize the area of the enclosure structure, column network distribution neatly, and take into account the expansion and maintenance convenience. Its plane is generally square, multi-storey cold storage is often built as dumbbell or monolithic. Dumbbell type will be divided into two independent enclosure structure of high temperature warehouse and low temperature warehouse, the middle to through the hall articulation, the use of better results. Monolithic in the high and low-temperature library with adiabatic wall will be floor and ground separation, library door and room temperature through the hall connected to the library door set up air curtains to prevent the library of cold air overflow. Cold storage walls, canopy, the ground should be paved with low thermal conductivity materials, such as rice husk, cork, asphalt, expanded perlite blocks, etc., as an adiabatic layer to prevent the outside world heat flow immersed in the library, increasing the heat load. In order to prevent outdoor water vapor to the insulation layer penetration, but also in the high temperature side of the insulation layer paved permeability resistance materials, such as asphalt linoleum as a gas barrier.　　Structural requirements Cold storage building from the beginning of construction to the installation of equipment is generally carried out at room temperature, the structural system is also in the state of room temperature; while the cold storage is put into use, the structural system is in a low-temperature environment. Due to the large temperature difference caused by the deformation of the structural system is much larger than the ordinary building, so it is necessary to carry out the temperature stress calculation in order to prevent the generation of "cold bridge". Anti-freezing measures should be taken for the floor to prevent the foundation from bulging and causing damage to the building. At the same time, frost-resistant materials should be used to enhance the frost resistance and durability of the structure.　The load-bearing structure of small-scale cold storage is generally a beam-and-slab structure, while large-scale multi-storey cold storage mostly adopts cast-in-place reinforced concrete beamless floor cover structure. In recent years, prefabricated assembled beamless floor cover and beamless floor cover frame structure constructed by ascending plate method are being gradually promoted. In addition to meeting the strength and stability of the enclosing wall structure design of the cold storage, it should also maintain the continuity of the adiabatic layer and the air insulation layer, so that it meets the thermal requirements of the building. The roof structure of cold storage is subject to direct sunlight for a long time, and will produce expansion or contraction deformation under the influence of temperature change. It is preferable to adopt prefabricated components so that the deformation can be adjusted between the components, thus reducing the total deformation. In order to prevent the unfavorable effect on the wall due to the expansion and contraction of the roof, a sliding contact surface can be designed between the roof structure and the wall.　Cold storage equipment General cold storage is mostly cooled by refrigerator, using liquid with very low vaporization temperature (ammonia or Freon) as coolant to evaporate under low-pressure and mechanically controlled conditions to absorb the heat inside the storage, thus achieving the purpose of cooling and cooling. The most commonly used is the compression type refrigerator, mainly by the compressor, condenser and evaporator tube and other components. According to the way the evaporator tube device can be divided into direct cooling and indirect cooling two kinds. Direct cooling will evaporate the tube installed in the refrigerated warehouse, liquid coolant through the low-pressure evaporator tube, direct absorption of heat in the warehouse and cooling. Indirect cooling is by the blower will be the warehouse air suction into the air cooling device, the air is hovering in the cooling device evaporator tube heat absorption, and then sent to the warehouse and cooling. The advantage of air cooling is rapid cooling, the temperature inside the warehouse is more uniform, and at the same time, it can bring the harmful gases such as carbon dioxide produced in the storage process out of the warehouse.　　Cold storage heat preservation: general cold storage and the outside world there is a significant temperature difference, the need to use thermal insulation materials to prevent the transfer of heat; commonly used insulation materials are polyurethane (sub-sheet and field spraying of two types), extrusion board, ordinary foam board and other types, especially in the field spraying molding polyurethane effect is the best, with a low coefficient of thermal conductivity and connected to a whole without splicing seams, with a high degree of cost-effective advantages.　　First, the characteristics and requirements of the cold storage building Cold storage is mainly used for frozen food processing and cold storage, it is through artificial refrigeration, so that the room to maintain a certain low temperature. Cold storage walls, floors and flat roofs are laid with a certain thickness of insulation materials to reduce the incoming heat from the outside world. In order to reduce the absorption of the sun's radiant energy, the surface of the cold storage wall is generally painted white or light color. Thus, the cold storage building is different from general industrial and civil buildings, and has its unique structure.　Cold storage building to prevent the diffusion of water vapor and air infiltration. Outdoor air intrusion not only increases the cold storage of cold consumption, but also to the warehouse with moisture, moisture condensation caused by the building structure, especially the heat insulation structure is damaged by moisture freezing, so we must set up moisture insulation layer, so that the cold storage building has a good sealing and moisture vapor barrier performance.　The foundation of cold storage is affected by low temperature, and the moisture in the soil is easy to be frozen. Due to the volume expansion of the soil after freezing, it will cause ground rupture and deformation of the whole building structure, and seriously make the cold storage can not be used. For this reason, low-temperature cold storage floor in addition to an effective heat insulation layer, the heat insulation layer under the treatment must be carried out to prevent the soil from freezing.　Cold storage floor to stack a large number of goods, but also to pass a variety of loading and unloading transportation machinery and equipment, flat roof also has refrigeration equipment or pipeline. Therefore, its structure should be strong and have a large bearing capacity.　In the low-temperature environment, especially in the cyclic freezing and thawing cycle process, the building structure is vulnerable to damage. Therefore, the building materials of the cold storage and the construction of the parts of the cold storage should have sufficient frost resistance.　In general, cold storage construction is to ensure the quality of the building by its strict insulation, sealing, robustness and frost resistance.　Ensure the quality of the building.　Second, the classification of cold storage (a) according to the size of the cold storage capacity points At present, the division of cold storage capacity is not unified, generally divided into large, medium and small. Large cold storage capacity in more than 10000t; medium-sized cold storage capacity in 1000 ~ 10000t; small cold storage capacity in 1000t below.　(ii) According to the cold storage design temperature, there are four major types of cold storage: high temperature, medium temperature, low temperature and ultra-low temperature. ① general high-temperature cold storage cold storage design temperature in -2 ℃ to +8 ℃; ② medium temperature cold storage cold storage design temperature in -10 ℃ to -23 ℃; ③ low-temperature, the temperature is generally in the -23 ℃ to 30 ℃; ④ ultra-low quick-freeze warehouse temperature is generally -30 ℃ to -80 ℃.　(C) according to the structure of the library body category 1. civil cold storage This is currently building more of a cold storage, can be built into a single-story or multi-story. The main body of the building is generally reinforced concrete frame structure or brick structure. The enclosure structure of civil cold storage is a heavy structure, thermal inertia is large, day and night fluctuations in outdoor air temperature and the outer surface of the enclosure structure by solar radiation caused by the day and night temperature fluctuations in the enclosure structure, attenuation is large, so the enclosure structure of the inner surface temperature fluctuations are small, the library temperature is easy to be stabilized.　2. Combined plate cold storage This cold storage is a single-story form, the library board for the steel frame lightweight prefabricated insulation board assembly structure, its load-bearing components are made of thin-walled steel. The inner and outer plates of the library board are colored steel (base material is galvanized steel), the core material of the library board is foamed rigid polyurethane or paste polystyrene foam board. As all the components are prefabricated according to uniform standards in specialized factories and assembled on site, the construction progress is fast and the construction cycle is short.　3. Soil-covered cold storage It is also known as soil kiln cold storage, the cave body is mostly arch-shaped structure, there is a single cave body type, there is also a continuous arch form. Generally for the masonry, and a certain thickness of loess cover as a heat insulation layer. Used as a low-temperature soil-covered cold storage, the foundation of the cave body should be in the sandstone layer or bedrock that is not easy to freeze and expand. Because it has the advantages of site-specific, local materials, construction is simple, low cost, durable and so on, in China's northwestern region has been greater development.　4. Cave cold storage is generally built in the rock is relatively hard, good integrity of the rock layer, the inner side of the cave is generally for lining or spray anchor treatment, the thickness of the rock cover of the cave body is generally not less than 20m A small cold storage is generally divided into indoor and outdoor type two kinds of 1. Cold storage outside the ambient temperature and humidity: the temperature of +35 ° C; relative humidity of 80%. 2. 2. Setting temperature inside the cold storage: freshness cold storage: +5～-5℃; refrigerated cold storage: -5～-20℃; low temperature cold storage: -25℃ 3. Temperature of the food into the cold storage: L-level cold storage: +30℃; D-level, J-level cold storage: +15℃. 4. 4. The stacked effective volume of the assembled cold storage is about 69% of the nominal volume, multiplied by the correction factor of 0.8 in the case of fruit and vegetable storage. 5. The daily intake of goods is 8-10% of the effective volume of the cold storage. Second, the body of the small cold storage Small cold storage is generally plastic spraying color steel plate as a panel, rigid polyurethane foam or high-density polystyrene as insulation, the library body has a good rigidity, high strength, heat insulation and heat preservation performance, flame retardant and other characteristics. Small cold storage library body is generally used within the wall of the plate embedded parts eccentric hook connection or on-site foaming fixed, sealing good installation and removal of convenient, on-site construction and installation work is small, labor-saving, good quality, quick results. Small cold storage with advanced refrigeration unit, library capacity and refrigeration equipment to match the whole reason, cooling speed, energy saving, and all automatic operation, safe and reliable operation. Small assembly cold storage is widely used, cold storage temperature range of 5 ℃ - 23 ℃, special assembly cold storage can be up to -30 ℃ below, to meet the needs of different purposes, applicable to a variety of industries and departments. Third, small cold storage refrigeration equipment selection Small cold storage refrigeration equipment is the heart of the refrigeration unit, commonly used small refrigeration unit common model selection of advanced fluorine refrigeration equipment, fluorine refrigeration equipment, more use of small impact on the environment of the refrigerant R22 and other new refrigerants. Fluorine refrigeration equipment is generally small, low noise, safe and reliable, high degree of automation, wide range of applications, suitable for small cold storage refrigeration equipment in the countryside. Small cold storage refrigeration machine and condenser and other equipment together often called refrigeration unit, refrigeration unit has water-cooled unit and air-cooled unit points. Small cold storage to air-cooled unit for the preferred form, it is simple, compact, easy to install, easy to operate, less ancillary equipment and other advantages, this refrigeration equipment is also easier to see. Refrigeration unit of the refrigeration machine is the heart of the refrigeration equipment, the common compression type refrigeration machine has open, semi-closed and fully closed type points. Totally enclosed compressor is small, low noise, low power consumption, high efficiency and energy saving. It is the first choice of small cold storage model, the air-cooled refrigeration unit composed of hermetic compressor-based, can be made into a split air conditioning like the form, hung on the wall mounted.　 Now on the market better hermetic refrigeration compressor, imported from developed countries or Sino-foreign joint venture refrigeration equipment product quality is more reliable, but the price is relatively high compared to the domestic machine to be more than 50% more than the more suitable for small towns and cities with refrigeration equipment cold storage. Fourth, small cold storage design points Cold storage library temperature is below 0 degrees (-16 degrees) of small assembly cold storage needs to be on the ground (library board) set 10 # channel steel overhead, so that the natural ventilation can be. Small cold storage, cold storage temperature 5 ~ -25 degrees, cold storage library board can be directly with the ground contact, but the ground should be flat. If the requirement is high, then you can place wood strips under the cold storage, overhead to enhance ventilation; also can be placed under the cold storage channel steel to enhance ventilation. Fifth, small cold storage project design and installation recommendations In recent years, the development of cold storage engineering and construction is more and more rapid, we know more and more in-depth cold storage, from building materials to a variety of cold storage equipment selection is becoming more mature. There are two common construction methods for cold storage project, one is assembly cold storage project and one is civil cold storage project. At present, the assembly type cold storage more choice of polyurethane library body: is the cold storage library board for polyurethane rigid foam (PU) for the sandwich, to plastic coated steel and other metal materials for the surface layer, will be the cold storage library board material superior thermal insulation properties and good mechanical strength combined together. With long years of heat preservation and insulation, simple maintenance, low cost and high strength, light weight and other characteristics, is one of the best choice of materials for cold storage thermal insulation library board, cold storage library board thickness is generally 150mm and 100mm two kinds. Most of the civil engineering cold storage project use PU polyurethane spray foam to do the thermal insulation library board. Most of the cold storage project refrigeration equipment selection with Freon refrigeration unit, large-scale cold storage more water-cooled units, small cold storage more air-cooled units; currently imported German Bitzer cold storage refrigeration unit and France's U.S. unit, smooth operation and low energy consumption, low failure rate, is the preferred unit of the current cold storage. Concerned about the cold storage project refrigeration equipment is configured reasonably important. This is because a reasonable match, reliable performance of the refrigeration unit, both to meet the product requirements of the cold storage refrigeration capacity and cold storage process requirements, but also save energy, low failure rate. Now some companies and individuals want to build a cold storage, the pursuit of low prices, ignoring the cold storage equipment configuration match is reasonable, resulting in the use of the refrigeration effect can not be achieved. Reasonable settings to match the cold storage project refrigeration equipment, build cold storage may increase investment, but in the long run save a lot of money and effort. Cold storage equipment after-sales service is also very important, cold storage equipment operation and maintenance and technical services are equally important. The vast number of building enterprises in the building of cold storage should be investigated in various aspects, listen to the views of other enterprises on the configuration of cold storage refrigeration equipment, and finally determine the practical program to build a cold storage. Make their own high starting point, high standards to establish their own cold storage, for their own best interests.