Views: 107 Author: Site Editor Publish Time: 2022-10-29 Origin: Site
I. Background of the Project People's demand for fresh fruits is also increasing, especially in some large and medium-sized cities,
and out-of-season consumption of fruits is becoming increasingly common. In order to solve the contradiction between seasonal
production and consumption of fruits, we must seek a new way to store fruits in large quantities and for a long time without losing
the original delicious flavor and nutrition. The appearance of modified atmosphere storage provides scientific methods and means
for long-term storage. Controlled atmosphere storage (CA) can automatically balance the contents of oxygen and carbon dioxide
in the warehouse, remove ethylene gas (ripening hormone) and control the temperature and humidity in the warehouse to achieve
the purpose of keeping fresh. Its main features are as follows: 1. Greatly prolong the storage period of fruits and vegetables, which
is 0.5-1 times longer than that of general cold storage. 2. It can keep the original quality and flavor of fruit. The hardness, color,
moisture, sugar, acid, VC and other components of fruits stored in controlled atmosphere storage can basically remain unchanged. 3.
It can inhibit the occurrence of fruit diseases and minimize the loss during storage. 4. After the fruits stored in the controlled atmos-
phere warehouse are delivered from the warehouse, the shelf-keeping period can be extended for three to four weeks, and the quality
and appearance will remain unchanged. According to the advantages of the above-mentioned modified atmosphere storage and fresh-
keeping warehouse, combined with the present situation and prospect of fruit production in * * * market, and enriching the life taste
needs of urban residents, it also provides a strong backing for fruit farmers to achieve high quality and yield, increase efficiency and
increase income, and effectively improve the enthusiasm of forestry and fruit industry production. Therefore, the construction of mo-
dified atmosphere fresh-keeping warehouse is proposed. II. Construction Scale and Product Plan Construction Scale: In order to solve
the problem of preservation and storage of real estate and famous and special fruits, especially the practical problem of increasing fruit
farmers' output but not increasing their income, the local fruit market is in a situation of oversupply. To expand the real estate fruit market
and improve the competitiveness of the real estate fruit market, increase the added value of products and the income of fruit farmers,
increase the supply of fresh fruits in winter, and improve the living standard of urban residents, the * * * * * Group plans to be located
in * * * * * city, * * * * * province. The fresh-keeping and storage products of this project are mainly high-quality fruits produced around
the city of * * * * in * * * * province. According to the investigation and research of product production and sales market and the local
fruit industry development plan, the scale of the modified atmosphere fresh-keeping warehouse of this project is planned to have a
reserve of 5,000 tons, and the total area of the fruit fresh-keeping warehouse is 7,398 square meters. According to the plan, construction
will be started at the end of * * * * 2022, with a planned construction period of one year. III. Overview of Project Design 3.1 Library plane
planning There are 16 controlled atmosphere fresh-keeping cold storages in this warehouse, and the size of the warehouse is about -2℃,
the lowest storage temperature. The main storage materials are fruits, with different varieties and vegetables. known conditions Net size in
cold storage: (length x width x height 6500) Net area in cold storage: 7,398 square meters Net volume in cold storage: 27,000 cubic meters
Maximum inventory: 5000T Temperature: +5℃~-2℃ (Te=-10℃,Tc=+45℃) Storage: fruits and vegetables Daily throughput: 100T/d Purchase
temperature: +25℃, Storage insulation: polyurethane double-sided color steel cold storage board with PIR thickness of 100MM. Control mode:
fully automatic Condensation mode: air-cooled condensation+evaporative condensation Refrigerant: R507 Six cold storages are equipped with
normal temperature buffer rooms on one side of the storage door, loading platforms should be provided outside the buffer rooms, and an
equipment room (machine room) should be set in the middle of the platform. Refrigeration and compression units and air conditioning equipment
in this area are all installed in the equipment room (machine room), and condensers are placed outside the wall or on the roof of the equipment
room. 3.2 refrigeration equipment refrigerant compressor unit According to the cold demand of the warehouse of this project, Biesel multi-head
parallel semi-closed/screw/piston refrigeration compressor unit is designed as the main refrigeration unit, and the number of units is 2. Refrige-
ration mode is mechanical refrigeration direct expansion, fully automatic PLC control. Its advantage is that it can automatically adjust the energy
according to the change of the purchase quantity, saving energy. At the same time, it has the function of mutual standby, which reduces the
installed capacity. Air-cooled condenser is adopted for condensation, which aims at convenient maintenance and simple system, and also reduces
the cost of daily maintenance. The compressor unit is arranged in the machine room to ensure that the equipment spacing is not less than 1.5m
for the main passage and 0.7m for the equipment spacing. In order to improve the utilization efficiency of machinery, considering the management,
maintenance, efficient operation of equipment, and energy saving, parallel piston/screw unit is adopted for refrigeration unit, and R507 is used as
refrigerant. Cold consumption calculation Calculation of cold consumption of 16 controlled atmosphere reservoirs in a reservoir area; (1) the calculated
cold consumption of each -2℃ controlled atmosphere storage: ****KW (2) Calculated cooling consumption of 16 controlled atmosphere warehouses:
kw (3) The platform area is equipped with a cold source according to the total cold consumption: 80%, and the refrigerating capacity of the refrigerator
should not be less than: kw. The daily incoming volume of a single room is 100 tons, and the incoming temperature is 25℃, which drops to -2℃ in 24
hours. Unit selection: Equipment selection for -2℃ controlled atmosphere storage in the reservoir area: Compressor unit selection: * * * * * type
air-cooled condensing parallel unit (2 sets) This unit is equipped with a Biesel piston compressor unit. The refrigerating capacity of a single compressor:
kW (refrigerating capacity at evaporation temperature: -10℃ and condensation temperature: 45℃) Total cooling capacity: kW, = meet the cooling capacity
demand. Operating power of unit: KW, power of condenser fan: KW, (When the condensing fan works at full capacity) Total operating power of each
warehouse type, hanging air cooler between warehouses, and each warehouse: 0.55X3X = KW, (1 set of 4 fans) The air cooler is equipped with external
balance thermal expansion valve of cold tons, with one (R507) in each warehouse. Three control cabinets. The condenser type ejector air-cooled condenser
is selected, and its heat exchange capacity is about kw, which meets the heat dissipation requirements of the unit. Overview of electronic control system
design for cold storage The integrated control system consists of the following main parts 1. PLC control system: Siemens S7 series products from
are selected. This part is responsible for controlling the main equipment of cold storage. As PLC has unparalleled stability, all the core control logic is
completed by it. The temperature and operating conditions of each warehouse are displayed through the PLC touch screen, and the equipment operating
data is displayed through the touch screen.
Second, touch screen (on-site human-machine interface)
Touch screen, full English interface, can display the operating status, temperature, humidity, oxygen content, nitrogen content, carbon dioxide content of each cold storage in real time, and can set relevant parameters. On-site modification and remote modification monitoring.
3. The temperature sensor transmitter uses the best temperature sensor
Cold storage defrosting method, adopts electric defrosting
According to the accumulated working time of the cold storage collected by PLC, it controls each cold storage to defrost one by one
Note: Regarding air conditioning equipment See also description and quotation for configuration.
The advantages of the BITZER parallel unit:
The cooling capacity is larger than that of the general refrigeration unit.
The compressor is produced by BITZER China.
Safe and efficient, it is the best choice to replace large ammonia refrigeration units.
Automatic energy adjustment, such as: multi-head parallel unit, can carry out 33%~66%~100%
energy adjustment, adapt to load changes and save energy.
Fully meet the requirements of load changes and energy saving, and can facilitate energy adjustment to achieve the best energy saving effect. It can be optimally matched at any time and in any occasion, and is always the most suitable solution, saving electricity by 30% to 50%.
Distribute the cooling load evenly through the refrigeration system, improve reliability and prolong life.
Small footprint, multiple compressors share the rack, the system layout is simple and compact, saving space.
The controller adopts computer precise control, imported control components, and the failure frequency is low.
Bitzer parallel unit adopts the principle of customized design, the production is customer-oriented, and it is really your own unit.
Bitzer parallel units can be repaired without affecting use, shortening abnormal downtime and reducing maintenance and maintenance costs.
Adopt reliable oil return guarantee devices (oil distributor, oil equalizing pipe, oil level adjuster, oil storage tank, etc.), negative pressure oil pump, accurate lubrication and reliable operation.
Integrated computer automatically controls the operation of the machine to achieve balanced use, which is both energy-saving and convenient.
The condensing pressure of the condenser has an automatic adjustment function, which can be used normally in winter and summer, and is not affected by seasonal changes.
Frosting can be achieved in separate zones, and the refrigeration and defrosting of each branch will not affect each other, ensuring that the refrigeration space and goods are always at a suitable temperature.
Air- cooled condensing system
The air-cooled condensing system has a lower condensing temperature and high cooling efficiency. Easy to use and simple to maintain. Introduction to the performance of ceiling-mounted air coolers The
fluorine air coolers use copper tubes and folded waves to strengthen aluminum alloy fins and a new process of hydraulic tube expansion
. Specially developed products for Freon refrigerants. It has the characteristics of compact structure, smaller volume, better thermal conductivity, uniform air supply, and easier frosting (the picture is for reference only, the actual product shall prevail).
The design situation is described in detail as follows:
(1) Design of the evaporator
tube expansion tube design: the use of large tube capacity and thick wall copper tube, and the entire large tube of aluminum alloy (thickness 0.2mm)
for hydraulic tube expansion, the large tube The close contact with the base tube can greatly increase the thermal conductivity.
Fin spacing design: In different warehouse frost conditions, different fin spacings are used to ensure high cooling efficiency, and effectively increase the defrosting interval to reduce the fluctuation of warehouse temperature caused by defrosting.
Design results: Due to the cross arrangement between the tubes, the heat exchange time between the wind and the finned tubes is prolonged, and the heat transfer efficiency is improved. At the same time, in order to reduce the resistance of the finned tubes, the method of thinning the thickness of the evaporator is adopted. It creates a smaller resistance inside the evaporator, so that the cold air can be evenly sent to the cold storage or processing room, and the wind can be sent farther.
(2) Overall structural design
Axial flow fan design: A special fan for low-noise cold storage is used, and the blades are made of aluminum alloy plates. Award), use special sealed motor for moisture-proof and waterproof, waterproof grade IP55, the motor and impeller are directly driven, which has the characteristics of high operation efficiency, uniform air supply, low noise, low power consumption, low vibration, reliable operation and long service life.
Design of water pan: When the temperature is high (8-15°C) when used in dividing rooms, packaging rooms, etc., the outer
surface is prone to frost due to the large temperature difference between inside and outside. Therefore, the structure to prevent frost is specially considered in the design. The design is to use polyurethane as the thermal insulation interlayer on the outside of the water pan and then stick the steel plate on the outside.
Technical requirements for fluorine coolers:
Ceiling coolers are composed of special fans for cold storage, rectifier sections, water spray sections, evaporators, water-receiving trays, water baffles and other components. Because the coolers have been placed in low-temperature, high-humidity cold storage or processing for a long time In the workshop, the use environment is very harsh, so the following technical requirements are put forward for the manufacture and material selection of the air cooler:
(1) The motor
impeller is made of aluminum alloy thin material, the wheel hub is formed by steel plate molding, the surface is treated by electrostatic spraying, and the motor adopts a joint venture. The motor, which not only ensures safety and efficiency, but also reasonably allocates investment costs, is directly connected to the drive. Under normal use and applicable environmental conditions, the bearing life of the motor is more than 40,000 hours.
(2) The evaporator
adopts copper tube and aluminum alloy sleeve, the copper tube is red copper tube φ16×0.5, and the aluminum plate is rust-proof aluminum plate with a thickness of 0.2 mm
(1000 series aluminum alloy plate). Set up finned tube middle plate brackets in the length direction of the heat exchange tube, and set up a group every 1.5M, and use aluminum alloy plate to prevent the heat exchange tube from being damaged during deformation and vibration. Elbow and pipe end (pipe end and header) are welded by air welding. And carry out 2.5Mpa air pressure resistance test without leakage.
The shell design
is directly made of color plastic steel plate or stainless steel plate (selected according to customer needs) and folded, which can fully meet the special requirements of low temperature and humidity in cold storage.
Design of water tray and water retaining plate
In order to improve the anti-corrosion performance, the water tray is made of color plastic steel plate or stainless steel plate (selected according to customer needs). The proper slope and inclination of the water-receiving pan is the key to draining the frost water in the water-receiving pan. Taking into account the condensation water droplets at the elbows at both ends and the water seepage at the inlet and outlet holes of the finned tubes at both ends when the water flushes frost, the water pan is extended to both sides, and all the elbows at both ends are included in the length of the water-receiving pan. Inside.
In addition, when water is used for frosting, there is a water baffle on the windward side of the evaporator. The appropriate spacing and angle (45°) of the water baffle will not only effectively block the water splashing during frosting, but also reduce the amount of water entering the evaporator. Wind resistance, reducing the loss of fan pressure. The water-receiving plate is connected with the upper frame by bolts, and a gasket is used to prevent the leakage of frost water. In order to reduce the condensation at the bottom of the water pan, the bottom of the water pan is made of polyurethane as the thermal insulation layer, and then pasted with a stainless steel plate, which can effectively prevent condensation at the bottom.
Air conditioning equipment
This scheme adopts two sets of automatic detection and control systems for air conditioning equipment to control the gas composition in the reservoir area. The equipment is mainly composed of hollow fiber membrane nitrogen generator, carbon dioxide remover, warehouse gas detection and control system, screw air compressor, and adjustment station. , storage gas balance valve, storage gas balance bag, etc.
3.3CA Series Hollow Fiber Membrane Nitrogen Generator
CA series nitrogen generator is specially designed for the matched use of the controlled atmosphere storage, to reduce the oxygen content in the controlled atmosphere storage, so that the fruit and vegetable products are in ideal storage conditions. CA series nitrogen generators use hollow fiber membranes from internationally renowned manufacturers as the main components of air separation, which have the characteristics of large air volume, small volume and long service life. The service life of the filter depends on the cleanliness of the environment, and is equipped with a series of functions such as regular drainage and pipeline overpressure protection.
The number of hollow fiber membrane nitrogen generators for this project is 2 units. Main functions and performance indicators of a single device
: Nitrogen production (at 95%): 36Nm3/h
Power supply: 220V±10%/50Hz/2kw
Dimensions: 800×600×2000 mm
3.4CT series carbon dioxide removal machine
CT series carbon dioxide remover is mainly used in combination with nitrogen generator and other controlled atmosphere storage equipment or used alone to control the percentage of carbon dioxide in the controlled atmosphere storage, so that fruit and vegetable products are under ideal storage conditions. The equipment adopts high-quality CO2 adsorbent, which has the characteristics of high absorption efficiency, fast regeneration and long service life. The key components in the equipment are selected from internationally renowned manufacturers, so the products have high reliability and long service life, and the performance of the whole machine is in a leading position among similar products in China. The carbon dioxide removal machine matching your project, its model is: , the number of units.
***** Main functions and performance indicators of a single device:
Removal capacity: 220kg/24h (under 3% concentration)
Power supply requirements: 380V±10%/50Hz/4kW
Weight: 780kg Import and
export Pipe diameter: Ф110mm
3.5***** series warehouse gas automatic detection and control
system valve. And automatically (or manually) control the opening and closing of warehouse valves and strippers according to the sampling results. Oxygen and carbon dioxide sensors do not need standard gas calibration, just ordinary atmosphere, easy to use, better than other products. The model of the automatic detection and control system for gas storage for your project is 2 units in quantity.
The functional performance indicators of the warehouse gas detection and control system are as follows:
On-line inspection and measurement of the percentage content of O2 and CO2 gas in the controlled atmosphere warehouse.
Touch screen to display, store and print O2 and CO2 gas percentage content.
Set O2 and CO2 control value and time.
Control the startup and shutdown of the carbon dioxide removal machine (automatic, manual).
Control the opening and closing of the warehouse connection valve (automatic, manual).
Measuring range: O2: 0%～21% CO2: 0%～10%
Accuracy : ±0.2%
External power supply: 220V±10%/50Hz/0.2kW Temperature
range: 10～35℃ Humidity
range: ≤90%RH Display
mode: cabinet touch screen display
Multiple machines can form a network, and can be matched with network computers.
3.6 Series warehouse air conditioning station
The series warehouse air conditioning station is the supporting equipment of the air conditioning warehouse. It gathers the pipelines of several warehouses in one place, so that it can be used with the nitrogen generator and carbon dioxide remover produced by our company, which is convenient for users to use, unified management, and beautiful in appearance. The adjustment station can greatly reduce the time and complexity of on-site construction. Better to ensure good air tightness between valve groups.
3.7 Humidification device
According to the customer's requirements for the humidity in the warehouse, each cold storage is equipped with a high-precision indoor air humidifier. The special centrifugal humidifier for air-conditioned warehouses is beautiful in appearance and practical. The balanced humidity field water mist particles exchange heat with the flowing air to achieve the purpose of humidifying the air.
3.8 Warehouse board
This project uses PIR-100 thick cold room board, which has the following characteristics:
1) High-quality raw materials: The raw materials produced by world-renowned manufacturers are used to ensure product quality.
2) Stable performance: High-pressure continuous foaming equipment and technology are used to make the batching accuracy of each chemical raw material reach 0.001, ensuring sufficient mixing, ensuring perfect foaming, and avoiding secondary foaming;
3) Green and environmentally friendly foaming agent: Using fluorine-free stock solution for foaming, no chlorofluorocarbons are produced, the greenhouse effect is
0, and there is no pollution to the environment; see the Pony test report.
4) High closed cell rate: the closed cell rate is greater than 97%, so that the water absorption rate of the core material is low and the thermal conductivity is lasting and stable;
5) Ultra-low thermal conductivity: the thermal conductivity of ≤0.021w/m2.k;
6) High-density core material: Polyurethane (PUR) with an average density of 42kg/m3 enables the composite board to have higher tensile and compressive strength;
7) Recyclable core material: The composite board can be recycled to protect the environment.
4. High-density foaming is used for one-time molding of air-conditioned cold storage door
, yellow orange-pattern sprayed 0.6mm color steel plate is used for outsourcing, 3mmPP plate is used for back panel, 6063-T5 aluminum alloy is used for one-time extrusion molding, and the outer coating adopts new electrophoresis treatment. High-performance heat-insulating flame-retardant polyurethane, self-extinguishing in 3-5 seconds with open flame, thermal conductivity: ≤0.023w/mk, melting weight ≥42kg/m3. Hand-pulled air-conditioning door with internal door opener with tripping function
5: Equipment power
The entire project considers refrigeration equipment power, air-conditioning equipment power, humidification equipment power, lighting power, and other production equipment power, and the configuration power supply is 380V-415V/3P /50Hz (60Hz) ≧300KW. It can be divided into two lines, and the single power line is copper wire YJV3*95mm+2.
The main structure of the construction period is planned to be enclosed by a single-layer rock wool board of steel structure, and the design and construction time of the steel structure is about 2-3 months. The cold storage installation time is about 3 months, and the entire project construction to use time is about 7-8 months.
Note: The above is just a rough description of the program we wrote for a project. for reference only. The specific project requirements are subject to the actual situation. Individual parameters in this scheme are all empty, specific design requirements for specific projects. For the reference of our customers.