Inspection method of refrigeration equipment in cold storage

Inspection method of refrigeration equipment in cold storage

1.Use the reverse operation of the system setting to evacuate the high-voltage system

1. System principle and evacuation path

System principle: condenser, liquid receiver, etc. -> compressor exhaust pipe -> reverse working valve (1) -> compressor suction valve -> compressor exhaust valve -> reverse working valve (2)- >Compressor suction pipe -> a 15 low pressure circulating barrel -> low pressure gas conditioning station -> evaporator.

　　 2. Features and applicable occasions

　　 (1) Stop the warehouse from cooling down.

　　 (2) Seriously affect the quality of goods in the warehouse. Discharging a large amount of high-pressure and high-temperature gas to the low-pressure system causes the evaporation pressure and warehouse temperature to rise rapidly, and the drain pipe defrosts and drips.

　　 (3) Caused brittle cracks at the welded parts of pipes and equipment. Because low-pressure pipelines and equipment are in a low temperature state for a long time, they are affected by dramatic changes in temperature.

　　 (4) Large energy loss. The reverse working time is too long, the power consumption is large, and it is not economical.

　　 (5) It is difficult to start the compressor when it resumes normal operation. After reverse work, the low pressure system pressure is too high.

　　 In view of the above reasons, this method is only used when there is no other feasible method, z* minimizes the amount of ammonia released to reduce the harm to the water source or the air.

　　 It must be pointed out: Reverse work is very useful for testing and evacuating repair welding of equipment pipes in newly-built cold storage refrigeration systems.

　　 2. Daily maintenance of cold storage

　　Insulation part:

　　1. After the cold storage and refrigeration equipment are newly installed or used for a long period of time, they should be tested and debugged thoroughly. Under the condition that all indicators are normal, they can be started and used under the guidance of professional refrigeration technicians.

　　 2. Insulation protection: Pay attention to the collision and scratching of hard objects on the cold storage body and outer body during use. Because it can cause dents and corrosion, severely, it will reduce the local insulation performance.

　　3. Sealing protection: Since the prefabricated cold storage is made up of several insulation boards, there are certain gaps between the boards. These gaps will be sealed with sealant during construction to prevent air and moisture from entering. So in use, repair some parts of the seal failure in time. We must resolutely put an end to the phenomenon of escape from cold.

　　4. Ground protection: Generally, small prefabricated cold storage uses thermal insulation boards. When using the cold storage, prevent a large amount of ice and water from being stored on the ground. If there is ice, do not use hard objects to beat or damage the ground during cleaning.

　　 3. Daily maintenance and maintenance of the refrigeration system

　　 1. Initial operation of the unit: Always observe the oil level and return of the compressor and the cleanliness of the oil. If the oil is dirty or the oil level has dropped, it should be resolved in time to avoid poor lubrication.

　　2. For the unit: clean the air cooler frequently to keep it in a good heat exchange state. Check whether the motor and fan rotate flexibly. If there is a blockage, add lubricating oil; if there is abnormal friction, replace the bearing of the same model and specification to clean the dirt on the fan blades, coil, and water pan. For the chiller unit, the condenser should be checked frequently, if there is a problem of scaling, the scale should be removed in time.

　　3. For the evaporator: always check the defrosting situation, whether the defrosting is effective in time, will affect the refrigeration effect and cause the refrigeration system to return liquid.

　　4. Frequently observe the compressor's operating status; check its exhaust temperature, and pay special attention to the system's operating status during seasonal operation, and adjust the system's liquid supply and condensation temperature in time.

　　5. Listen carefully to the running sound of the compressor and condenser fan, and deal with any abnormalities in time. At the same time, check the vibration of the compressor, exhaust pipe and footing. Check the compressor for unusual smell.

6. Maintenance of the compressor; the internal cleanliness of the initial system is poor, and the refrigerating oil should be replaced after 30 days of operation. For systems with higher cleanliness, it should be completely replaced after half a year of operation (depending on the actual situation) . Compressor maintenance: refrigeration technicians inspect and maintain the compressor once a year. Check the compressor oil level and oil color. If the oil level is lower than the 1/2 position of the sight glass, the cause of the oil leakage should be found out and the fault should be eliminated before refilling with lubricant; if the oil has changed color, the lubricant should be completely replaced. Check whether there is air in the refrigeration system, if so, discharge air:

　　A) Insulation resistance of compressor motor (normally above 0.5MΩ);

　　B) Compressor operating current (normally rated value, three-phase basically balanced);

　　C) Compressor oil pressure;

　　D) Compressor shell temperature;

　　E) Inspiratory pressure;

　　7. Maintenance of solenoid control valve and differential pressure control valve:

　　A) Filter drier: Check whether the filter drier is dirty or absorbing moisture, if so, replace the drier filter with the same specification;

　　B) Solenoid regulating valve, differential pressure regulating valve:

　　――Check whether the solenoid control valve and differential pressure control valve are reliable in operation. If there is any problem, replace the solenoid control valve and differential pressure control valve of the same specification;

　　4. The entire refrigeration system is equipped with a complete and reliable electrical control system

Under the premise of meeting the design requirements and achieving more advanced and smarter control and more economical system operation, the following control scheme is proposed: The main control of the cold storage adopts two sets of centralized display and centralized display composed of programmable logic controllers and man-machine interfaces. The control system (TCS system) is hereinafter referred to as the DCS system. The system functions are as follows;

　　 1. System variable display

The system can display the real-time variables of the system on the screen in digital or Chinese form. For example, the temperature in each library and the temperature of each tube row can be displayed on the screen. It can display not only digital but also dynamic bar graphs and dynamic tables. Important variables are displayed more clearly and intuitively.

　　 2. System working parameter display

The so-called system working parameters are the parameters required for the system to work within the range of user requirements. TCS can collectively display all the working parameters that need to be set on one or several screens, so that the operator can quickly observe the need for correction in time. Data, so as to avoid production delays due to the data not being corrected in time.

　　3. System status display

DCS can not only display system working parameters and system variables, but also display the status of system hardware with three-dimensional indicator lights. For example, when the No. 1 compressor is working, its corresponding three-dimensional indicator lights will move on the screen. In this way, the entire screen is embellished with a vivid image, fully expressing the automatic "flexibility"!

　　4. Real-time event login

When the system hardware or software is abnormal, the operation screen will display the abnormal situation in the event screen in Chinese. If the event is a failure event, the system will sound an alarm and stop the malfunctioning hardware, and give Prompt information, reminding the operator which place should be checked to eliminate the fault, which brings great convenience to maintenance.

　　 5. Password function

After adding the password function to the system screen, some important screens can be effectively protected and divided into several security levels, so that the operator who masters the low security level screen can not access the high security level screen (it will not cause operation deviance) , And the operator who masters the high security level screen can access both the high security level screen and the bottom security level screen. The operator who masters these level screens is generally an engineer or workshop director.

　　 6. Communication function

When only operating the control system in the computer room cannot meet the control requirements, you can connect the host computer to form a tree or top network to achieve centralized remote control. At this time, you can add a hub to the PLC communication port, and the host computer can connect to one The communication port, text display, etc. form a network system, so that all advanced control requirements can be easily realized.

The temperature of each cold storage is individually controlled, the graphic interface is displayed, and the operation is simple; the operation of the cooling fan and solenoid valve of the refrigeration system is automatically controlled; the temperature of each storage can be independently set according to the user's needs; Frost: The liquid supply solenoid valve is opened with a delay, and there is a drainage time setting after frosting. The delayed operation of the air cooler will not blow the water droplets on the air cooler after frosting into the library. This design is very scientific and advanced.

　　According to the needs of users, our company provides a centralized central control system, the host adopts Siemens PLC, the man-machine interface adopts a color touch screen, and remote communication, control ports and printer ports can be added. The control system can design the operation plan of the unit in a humane manner according to the user's actual usage rules. It can be switched on and off regularly, and run in time intervals to make full use of low-priced electricity at low grid load, thereby further reducing user operating costs.

　　The control system has perfect protection and alarm functions. Voltage phase loss, voltage too high, too low, unit high and low pressure over limit, compressor over current, overheat and other full-function automatic protection, and display the failure of each main component in the form of code and have sound and light alarm.