CBFI AT60 60 Tons Per Day Ammonia Refrigerant Tube Ice Machine

In the ice making machine industry, ammonia refrigeration and fluorine refrigeration have always been the focus of controversy. The choice of refrigeration method can maximize the economic, environmental and social benefits. This article objectively analyzes the nature of ammonia, fluorine refrigerants and ammonia and fluorine refrigeration systems, and summarizes the application status, existing problems, and research directions of the two refrigeration methods in the industry, which will help people have a clear understanding of these two refrigeration methods. To understanding.1. Comparison of properties of ammonia refrigerant (R717) and fluorine refrigerant (R22 and R404A)In terms of safety: the explosiveness and toxicity of ammonia greatly limit its application, and with the frequent news of ammonia refrigeration systems in recent years, people have a certain fear of ammonia refrigeration systems. The high safety of fluorine refrigerants is the main reason for the rapid development of fluorine refrigeration systems in recent years.Environmental protection: ODP of ammonia is zero, and GWP is also zero. R404A is a more environmentally friendly refrigerant, and R22 refrigerant due to its poor environmental performance, developing countries will restrict its application before 2020. At present, people in the industry are actively looking for alternative refrigerants that are more environmentally friendly.Material compatibility: When ammonia contains moisture, it is corrosive to copper. Therefore, copper and copper alloys cannot be used for the pipes and valves of the ammonia system. There are certain limitations in the selection of system equipment materials. Fluorine refrigerants have high chemical and thermal stability, and theoretically they are not corrosive to all metals. Interaction with water: the allowable water content of ammonia is less than 0.2%. Because ammonia is easily soluble in water, even if there is a trace amount of water, it will not appear "ice plug" like Freon, so it is necessary to dry the ammonia refrigeration system to the pipeline system. The requirements are not as strict as Freon. Freon is difficult to dissolve in water, so if there is water in the system, it is easy to cause ice clogging. Usually we have a filter drier in the system. Interaction with oil: At present, the lubricating oil of ammonia refrigeration system is mineral oil, which cannot be miscible with ammonia. Equipment such as oil separator and oil collector are usually installed to return the lubricating oil to the compressor through automatic or manual control. R404A is not miscible with mineral oil and alkylbenzene oil, but it can be miscible with polyester oil (POE). However, at high temperatures (around 50°C), there will be insoluble stratification, and R22 is also slightly soluble in lubricating oil. Therefore, large-scale fluorine refrigeration systems are usually equipped with oil and oil reservoirs. Take R404A as an example. The difference between the two compressors is only the refrigerant. Compare the cooling capacity of R717, R22 and R404A under the same evaporating temperature (-10°C), condensation temperature (45°C), liquid subcooling (0K) and suction superheating (10K). Ammonia has more advantages than fluorine in terms of cooling capacity, COP, and mass flow. However, the exhaust temperature of R717 is much higher than that of R22 and R404A, which will increase the configuration requirements of system components. Ammonia has a much larger refrigeration capacity per unit mass of fluorine, indicating that ammonia has a better refrigeration capacity. However, when the evaporation temperature reaches -33.33℃, the gauge pressure of ammonia is 0. In order to avoid the system working under negative pressure, ammonia is generally used For systems where the evaporation temperature is above -33.33°C.2. System complexityTube ice machine Ammonia refrigeration is a pump-supply system. Since the mineral lubricating oil used in the ammonia refrigeration system is not miscible with ammonia, the ammonia system is indispensable for oil separators, oil collectors and other equipment to ensure the oil return of the system and reduce the system temperature, so that the ammonia The oil system is very complicated. These make the ammonia system huge, many auxiliary machines, complicated pipelines, many valves, complicated construction, and long construction period. The fluorine system has a compact structure, a small footprint, and few accessories. The configuration of the unit has been very complete, and most of it can be completed in the factory of the unit supplier.3. Equipment investmentThe ammonia system includes a lot of equipment, mainly including compressors, evaporators, condensers, oil separators, high and low pressure storage tanks, intercoolers, recoolers, ammonia separators, low pressure circulation tanks, and emergency ammonia discharge devices. , Air vent, oil collector, ammonia pump and corresponding valve parts and bypass valve, etc., resulting in a lot of on-site installation workload. The main equipment of the fluorine system includes compressors, evaporators, condensers, oil separators, oil collectors, gas-liquid separators, liquid reservoirs and corresponding valves, etc. Generally, the fluorine system uses copper pipes or steel pipes, which is convenient to take over. , The pipe layout is simple, and the pipe consumption is less than that of the ammonia system. The cost of investment in ammonia and fluorine refrigeration equipment is at the same level of equipment quality and control methods. For small cold storage (compressors less than 50Hp), the price of fluorine is more than 10% lower than that of ammonia equipment. The prices of large and medium-sized cold storages are almost the same. If imported or imported domestically assembled fluorine refrigeration equipment is used, it is more than 30% cheaper than imported ammonia refrigeration equipment, but 20%-30% more expensive than domestic ammonia refrigeration equipment.4. Degree of automationBecause the valves of the domestic ammonia system are affected by valve material, processing equipment and processing technology, the leakage problem of the valves of the ammonia system is serious, and it is difficult to achieve a high degree of automatic control. Specialized personnel are required for 24-hour management (Note: There are also automated ammonia storages, but they are relatively few). The fluorine system is easy to realize highly integrated and relatively stable automatic control due to the mature products and stable performance of various components, and basically realizes the unattended operation of the system. Due to the hazards of Freon refrigerants to the atmospheric environment, the use of fluorine refrigeration has been restricted in recent years. Therefore, actively looking for more ideal refrigerants is the development direction of fluorine refrigeration. People have made positive progress in the search for alternative refrigerants of Freon. Some experts and scholars pointed out that the better refrigerants to replace R22 are R407C, R410A and R32.ConclusionA comparative analysis of the advantages and disadvantages of ammonia and fluorine refrigerants from the characteristics of refrigerants and current application characteristics shows that ammonia refrigeration has better refrigeration performance, and the toxicity and danger of ammonia are what we have to consider, so we need to continue Research and improve the objective problems of ammonia refrigeration system. The better safety and simplicity of fluorine refrigeration is widely used in small and medium-sized cold storage, and there is also a trend toward large-scale development. However, the hazards of Freon to the atmospheric environment have to be paid attention to. Therefore, it is still to find more ideal refrigerants. The focus and direction of future research.

      The ice making machine cooler is a type of heat exchange equipment used to cool fluids. Water or air is usually used as a coolant to remove heat. Mainly can be divided into tube cooler, plate cooler and air-cooled cooler. When the copper tube of the tube cooler is damaged and leaks, if the tube plug is used to block it, the total number of blockages shall not exceed 10% of the total number of tubes (or according to the requirements of the cooler product manual). According to the water quality and oil quality, carry out the inspection and cleaning of the fouling on the tube wall surface of the tube cooler.      The cleaning method of the tube cooler is as follows:　   1. Cleaning the water side of the tube cooler　   A. Trichloroethylene solution can be used for flushing, so that the cleaning liquid circulates in the cooler. The pressure of the solution is not greater than 0.63MPa, and the flow direction of the solution is preferably opposite to the direction of the oil flow in the cooler. The cleaning time depends on the dirt. After rinsing, introduce clean water into the cleaning until the water flowing out is clean by visual inspection.      B. You can also use carbon tetrachloride soak, pour the solution into the cooler, and watch the color of the solution after 15-20 minutes. If it is severely turbid, replace it with a new solution and repeat the soaking until the color of the solution after soaking is similar to that when it is clean. Then introduce clean water into the cleaning, until the outflow of water is clean by visual inspection.　  C.If there is no obvious structure in the water side pipeline, you can clean it with the corresponding brush according to the diameter of the pipeline, and then rinse it with clean water.　　2. After cleaning the tube cooler, perform a water pressure test. The cavity between the tubes of the tube cooler shall be tested for tightness with water according to its nominal pressure or 1.25 times the working pressure, and the pressure shall be maintained for 30 minutes, and there shall be no leakage at the expanded tube or welded joint. The water must be completely drained after the test.　　3. Check the heat exchange effect of the tube cooler. After the lubricating oil is cooled by the cooler, the temperature can generally be reduced by 5-10℃, and the temperature of the cooling water can be increased by 3-5℃.　　4. The connecting oil ports of the tube cooler must not be opened for no reason during the cleaning process, and must be sealed with bulkheads or flange covers.        Let us understand the difference between the cooler and the condenser of the ice maker:Condenser and cooler are also one of the important parts of heat exchange equipment in the heat exchange process. The main differences between the two are as follows:1. The cooler has no phase change, and the condenser has a phase change but the pipeline entering and exiting the cooler does not change. Generally, the pipe diameter is different from the inlet and the outlet, and the pipe diameter of the inlet and outlet of the condenser changes greatly, which is relatively easy. watch.2. The settings of the baffles of the two are different, the cooler is set up and down, and the condenser is set up and down, and the heat transfer coefficient is also different.3. There will be a liquid level gauge and a liquid level control port on the cooler, but the condenser does not. The air inlet and air outlet of the cooler are both at the upper part of the container and the pipe diameter is basically the same, while the air outlet of the condenser is at the bottom of the container, and the pipe diameter is different from the air inlet. The inlet and outlet of the intercooled ammonia liquid are under the container, while the water inlet and outlet of the condenser are not. The vertical type is generally one up and down, while the horizontal type is at one end of the container. 

      For long-term use of cold storage room, various technical indicators must be checked regularly and adjusted in time. The operating temperature and pressure of the cold storage system, as well as the amount of lubricating oil and refrigerant, must be checked and adjusted in time. The system should have automatic control and compressor alarm devices. Once there is a problem, an alarm will be issued, or an automatic protective shutdown and the compressor will stop. Here are 7 common problems and solutions for the use of cold storage room.      1. The installation environment and maintenance of the air coolerThe location and environment of the air cooler inside the cold storage will affect its operation. Generally, the air cooler near the cold storage door is prone to condensation and frost. Although the air cooler can automatically heat and defrost at regular intervals, if the door is opened too frequently, the opening time is too long, the time and quantity of hot air entering is long, the defrosting effect of the fan is not good. Because the defrosting time of the air cooler cannot be too long, otherwise the cooling time will be relatively shortened, the cooling effect will not be good, and the storage temperature cannot be guaranteed.Kogamaru       2. Drainage of the melted water during the defrosting of the air cooler　　This problem is related to the severity of the frosting. Due to the severe frosting of the fan, a large amount of condensate will inevitably be produced. The fan's drain pan cannot bear it, and the drainage is not smooth, and it will leak and flow to the ground in the warehouse. If there are goods stored below, the goods will be soaked. In this case, a thicker draft tube can be installed to remove the condensate.　　Some air coolers have the problem of blowing water from the fan and spraying it on the stock in the warehouse. This is also the frosting problem of the fan in the cold and heat exchange environment, mainly due to the condensate generated by the fan leaf in the hot environment, rather than the problem of the defrosting effect of the fan itself.　　3.the problem of the condenser fan motor and the electric heating tube of the air cooler　　 This is a vulnerable part. The fan motor that runs for a long time in a high temperature environment may malfunction and be damaged. If the guaranteed temperature of the cold storage is very important, some vulnerable parts should be ordered for timely maintenance.　　4. the ambient temperature of the condenser　　The condenser is generally installed on the roof of an outdoor building. In an environment with a high temperature in summer, the temperature of the condenser itself is very high, which increases the operating pressure of the unit. If there is a lot of hot weather, you can add a pergola on the roof condensation to block the sun and reduce the temperature of the condenser, so as to reduce the pressure of the machine, protect the unit equipment, and ensure the temperature of the cold storage. Of course, if the unit capacity is sufficient to ensure the storage temperature, there is no need to build a pergola.　　　 5. The problem of low compressor efficiency　　 Due to the long-term operation of the compressor, the cylinder liner, piston ring and other parts will be severely worn and the fit clearance will increase. The sealing performance will be correspondingly reduced. The compressor's air delivery coefficient will also be reduced, and the cooling capacity will be reduced. The refrigeration capacity of the compressor can be roughly judged by observing the suction and discharge pressure of the compressor. If the refrigeration capacity of the compressor drops, the common method is to replace the cylinder liner and piston ring of the compressor.　　 6. there is a problem of more air or refrigerated oil in the cold storage evaporatorOnce more refrigerating oil is attached to the inner surface of the heat transfer tube of the cold storage evaporator, its heat transfer coefficient will decrease. Similarly, if there is more air in the heat transfer tube, the heat transfer area of the evaporator will decrease, and its heat transfer coefficient will decrease. The thermal efficiency will also drop significantly, and the temperature drop rate of the warehouse will slow down accordingly. Therefore, in daily operation and maintenance, attention should be paid to timely removing oil stains on the inner surface of the heat transfer tube of the evaporator and exhausting the air in the evaporator.　　7. the cold storage throttle valve is improperly adjusted or blocked, the refrigerant flow is too large or too smallWhen the throttle valve is opened too large, the refrigerant flow is too large, and the evaporating pressure and evaporating temperature will also increase, and the temperature drop rate of the warehouse will slow down; at the same time, when the throttle valve is opened too small or blocked, the refrigerant The flow rate also decreases, the cooling capacity of the system also decreases, and the temperature drop rate of the warehouse will also slow down.　　 Generally, it can be judged whether the refrigerant flow rate of the throttle valve is appropriate by observing the evaporating pressure, evaporating temperature and frosting of the suction pipe. To Clogging is an important factor that affects the flow of refrigerant. The main cause of throttling valve blockage is ice blockage and dirty blockage.　　Ice blockage is due to the poor drying effect of the dryer. The refrigerant contains moisture. When it flows through the throttle valve, the temperature drops below 0°C. The moisture in the refrigerant freezes and blocks the throttle valve hole.　　 Dirty blockage is caused by the accumulation of more dirt on the inlet filter of the throttle valve, and the flow of refrigerant is not smooth, resulting in blockage.

         Potato cold storage preservation technology mainly includes three aspects: pre-harvest management, cold storage storage period management and delivery management. Let's learn about the temperature of the potato cold storage room and the precautions for management in the storage.         1. Temperature, humidity and gas composition management of potato cold storage　　 Cold storage fresh-keeping potatoes (potatoes) can be stored in fresh-keeping warehouses or controlled atmosphere warehouses. The temperature and humidity standards of potato (potato) fresh-keeping cold storage are as follows:　　 (1) Temperature management　　 Fresh-keeping cold storage or air-conditioning temperature is 3℃~5℃.The storage temperature is required to reach the specified storage temperature within 48 hours, and the storage temperature must be stable during the entire storage period and the fluctuation should not exceed ±1°C.        When the temperature is higher than 5°C, individual molds start to move, and when the temperature is 8～11°C, the tuber respiration is strong, the fungus multiplies rapidly, and the tuber is prone to rot.　　 When the temperature is 0～1℃, the starch in the potato chunks begins to be converted into sugar, the taste becomes sweeter, and the seed potatoes deteriorate; when the temperature is lower than -1℃, the potato chunks are frozen, and then a lot of rot.　　 (2) Relative humidity management　　The relative humidity of the potato cold storage is kept at 80%～90%.　　 If the humidity is higher than this, the potato pieces are easy to rot and germinate early; if the degree is too low, the potato pieces are easy to lose water, lose weight, become soft and shrink, and lose their edible and seed value.　　 (3) Management of gas environment in potato cold storageThe gas environment of the potato cold storage will affect the storage effect of potatoes. The management recommendations are as follows:Benzathine penicillin: long-acting penicillin　　①Gas environment management of potato fresh-keeping cold storage　　 The potato fresh-keeping warehouse is a relatively sealed environment, after being stored in the warehouse for a period of time.　　 Due to the respiration of the potato itself, the concentration of carbon dioxide in the reservoir will increase and the gas will become turbid.　　Excessively high concentrations of carbon dioxide can cause "poisoning" of potatoes and even rot and deterioration of potatoes.　　 Therefore, it is recommended to ventilate the warehouse body, and choose the morning or evening when the temperature is lower. The warehouse is usually ventilated at least once a week.　　②Gas environment management of potato controlled atmosphere storageThe gas environment of the potato controlled atmosphere storage is recommended to be controlled as: oxygen concentration 3%~5%, carbon dioxide concentration 2%~3%.　　 The respiration of potatoes is still going on after harvesting. Potatoes with too low oxygen content will be hypoxic. In some cases, they will lose their germination ability, and in severe cases, they will cause suffocating rot.　　 The appropriate concentration of carbon dioxide concentration can also slow down the respiration of fresh potatoes, which can effectively delayThe priming effect of breathing jumps.　　 But the carbon dioxide concentration can not be too high, too high carbon dioxide will cause potatoes to be forced to undergo "anaerobic respiration".　　 refers to the process in which the respiratory substrate of potatoes cannot be completely oxidized under hypoxic conditions to produce alcohol, aldehyde, lactic acid and other products, and at the same time release a small amount of energy. The reaction equation is as follows:　　 Anaerobic respiration is not good for potato storage, it will consume more nutrients stored in potatoes and accelerate the aging of fruits and vegetables.In addition to controlling the carbon dioxide and oxygen components, the air conditioning warehouse also controls the concentration of ethylene. Ethylene can quickly increase the respiratory intensity of potatoes and accelerate the ripening of potatoes. The ethylene removal machine of the air conditioning warehouse can control and reduce the concentration of ethylene.　　 (1) During the storage period, samples should be checked regularly to check whether the potatoes (potatoes) have disease, cold damage, color change, water loss and rot, and remove them in time if they are abnormal.(2) The fresh-keeping warehouse should be well ventilated, which should be carried out at least once a week due to the temperature drop or in the evening.　　 2. Potato delivery management　　 After the cold storage storage period is over, the following three points need to be paid attention to when potatoes are shipped out of the warehouse:　　The potatoes out of the warehouse should be slowly warmed up to prevent the dew and deterioration of the potatoes caused by the excessive temperature difference;　　Attention during handling: handle, put, and move gently to avoid mechanical damage;　　Cold chain transportation should be implemented for medium and long-distance transportation, and normal temperature transportation can be selected for medium- and short-distance transportation.