Management and Application of Cold Storage Automation

Cold storage after the original mechanical refrigeration, ammonia equipment refrigeration, refrigeration fluorine equipment until now environmental protection and energy saving cold storage, step by step to today more energy saving, more environmentally friendly, more effective automation management.

The main characteristics and problems of energy saving control system of 1. cold storage

1, cold storage equipment automatic control level is low, completely dependent on manual operation, and people's subjective initiative and technical level, etc., due to people and time, there are great differences, it is difficult to achieve better control.

2. The compressor star-triangle will impact the compressor equipment and the power grid when starting, which will affect the service life of the equipment. Moreover, the equipment can only run at full speed after starting, and the refrigeration capacity can be controlled by adjusting the opening degree of the return valve (evaporation pressure). Cause waste of power consumption, equipment failure rate is high, the operation of the economy is poor.

3. It is difficult for each branch library to automatically adjust the refrigerating capacity according to its own requirements according to different storage materials or changes in incoming and outgoing storage conditions and differences in heat preservation performance, thus causing excessive refrigeration waste to the branch library that did not need refrigeration. Evaporator defrosting and cooling water pump operation are difficult to achieve good results.

The purpose of 2. automation control transformation With the development of electronic technology, programmable logic controller (PLC), AC frequency conversion speed control technology mature development, a large number of applications of various types of sensor transmitters, making the automation control function more and more powerful, system optimization and energy management control ability is also more and more strong. It provides a good prerequisite for the automation of cold storage.

The purpose of the transformation is to realize automatic intelligent control, improve the storage quality of cold storage, reduce power consumption, improve the service life of equipment, reduce the failure rate of equipment, and reduce the cost of personnel on duty. Comprehensive improvement of cold storage efficiency, 2 years to ensure recovery of investment costs.

The main work of 3. equipment transformation
1. The automatic control system of the cold storage adopts S7 PLC control and programming. Data communication between the upper computer is realized through MPI communication. For large cold storage, Profibus-dp communication is adopted to realize full data exchange with each branch cold storage and cooling room control equipment;

2. The refrigeration compressor is driven by AC frequency conversion speed regulating device, and the full data exchange and control are realized through modbus communication and PLC;

3, with the upper computer industrial touch display (or touch screen) wincc configuration software to make the upper computer management screen of the cold storage system. Real-time dynamic display of the operating status of all equipment in the cold storage, record equipment operating parameters and operating curves to provide energy-saving data analysis data, real-time alarm of various abnormal phenomena.

4. The intake valve of the regulating station is changed to an electric mechanism, and various sensors are added to realize PLC automatic control.

5. Realize the automatic operation and debugging of the refrigeration system of the aquatic cold storage.

Functions of 4. equipment after transformation:

1. The whole cold storage system is managed and controlled by the upper computer. On the upper computer, the temperature of each cooling room of the cold storage, the operation status of the compressor and the working status of each point of the equipment are displayed in real time with pictures, such as the start and stop of the equipment, operation, fault, valve control status, set temperature value and actual control value of each cooling room, and the operation load current of the compressor are recorded with curves. The temperature, pressure and other parameters to achieve real-time monitoring alarm prompt, display the return valve pressure and other parameters and operating equipment operation. It has a process temperature for different refrigeration rooms to store different storage materials, and a database of process parameters such as storage temperature and better refrigeration capacity (return air pressure) is set for users to call.

2. The system is considered according to the unattended scheme, and the temperature of each cold storage is separately detected and controlled, so as to realize the closed-loop control of the valve opening and closing degree and the measured temperature of the warehouse at that time. Temperature detection and control using PLC, temperature control range of high precision; cold storage measured temperature and set temperature are displayed on the touch screen, and has an upper limit, lower limit alarm function.

3. The system has the dual-position operation function of automatic and manual control, and is equipped with a variety of automatic protection devices. When a fault occurs, it will automatically give an alarm signal (which can be transmitted remotely) to remind the user to deal with it. When a serious accident occurs, it will automatically stop and alarm. If necessary, the user may notify the user by sending a short message notification. The system has the advantages of accurate temperature control, simple operation and high reliability.

4. The compressor has the function of soft start, soft stop and continuous smooth speed regulation, which can extend the life of the equipment and realize energy saving adjustment. Intelligent fuzzy start-stop control is carried out according to the measured temperature of each cold room to reduce the number of start-stop.

5. According to the process requirements, different working modes such as warehousing, warehousing and storage are set. According to the actual situation of different warehouses, separate automatic control is carried out. Through PLC programming, different temperatures are set according to the storage requirements of warehouse storage, and the speed of liquid supply valve or air cooler is automatically adjusted, which not only meets the freezing (refrigerating) requirements of different freezing rooms, but also avoids the waste of excessive freezing of individual warehouses. In this way, the temperature warehouse adjustment can meet the requirements of energy saving, and can also meet the needs of high-precision temperature adjustment in some warehouses. The temperature control can reach the accuracy requirement of 0.250C.

6, the use of peak and valley electricity prices, night to do refrigeration energy-saving reserves, reduce electricity consumption.

7. It has the function of closed-loop adjustment and stabilization of return air pressure to realize energy-saving operation control mode; The control valve of the regulating station is automatically adjusted according to the difference between the actual temperature and the set temperature between the corresponding freezing (refrigerating) rooms and the temperature difference between the refrigerators. When there is no difference, the valve is closed, the opening degree of the valve increases automatically when the difference is large, and the opening degree of the valve decreases automatically when the difference is small.

8. Automatically detect the frosting state of the condenser and defrost in time to ensure the freezing efficiency.

9. For the circulating water cooling system, according to the ambient temperature and the actual working temperature, the working state of the cooling effect is guaranteed, and the closed-loop control automatic adjustment function is realized.

10, all fan operation monitoring function, any fan to stop running, immediately give alarm information.