I have a question regarding the refrigerant ratio!

The specific ratio of the refrigerant is usually determined based on actual production requirements and the design specifications of the refrigeration system. For a mixed refrigerant of methane, ethylene, isopentane, and propane, you need to first consult the design specifications for the refrigeration equipment and system, or seek advice from the equipment manufacturer for the recommended ratio. During normal production, formulating a refrigerant generally requires following these steps: 1. Determine the actual composition and proportions of the refrigerant in the current system, which can be done using specialized refrigerant analysis instruments. 2. Based on the analysis results and cooling requirements, calculate the amount of each component refrigerant that needs to be added or replaced. 3. Ensure the system is shut down before operating, and take necessary safety measures. 4. Add or replace the refrigerant using specialized refrigerant filling equipment according to the calculated proportions. 5. After filling, perform a leak check on the system to ensure there are no leaks. 6. Restart the system and observe its operation and temperature changes to confirm that the refrigerant ratio adjustment was successful. When handling refrigerant, it is essential to use the correct methods and tools to prevent refrigerant leaks or safety incidents. If you are not familiar with the procedure, it is recommended to have a professional carry it out. .

The ratio of the refrigerants is not fixed; the amount of each component is determined according to the design. The boiling point of isopentane is 27.8°C, that of propane is -42.1°C, that of ethylene is -103.7°C, and that of methane is 161.5°C. In a cryogenic chamber, cooling occurs layer by layer through reduced pressure and vaporization, based on the different boiling points of the refrigerants. The amount of refrigerant in each layer can be determined by observing the temperature trend from top to bottom in the chamber. Of course, if the temperature in an upper layer does not reach the specified value, it will affect the cooling effect in the lower layers, necessitating the addition of more refrigerant, with the design values serving as the main guide for making such decisions

Thank you. What is the general recommended ratio for the refrigerant?

Each design institute uses different components for the refrigerant; based on what those institutes use, we employ 12% nitrogen, 28% ethylene, 35% methane, 19% isobutane, and 6% isopentane. It seems that your refrigerant lacks a component with a boiling point lower than that of methane – the boiling point of nitrogen used by us is -196.5 degrees Celsius℃

This post was last edited by Tanran_VRPN on 2024-9-25 at 10:40. During the normal operation of an LNG cryogenic tank, the key to adjusting the refrigerant lies in maintaining a balance of cooling capacity, which involves managing the components of the mixed refrigerant, controlling the flow rate of the feed gas, and monitoring the operating conditions of the cryogenic tank. The following are the specific methods for preparing the refrigerant: Control the components of the mixed refrigerant: The components of the mixed refrigerant have a significant impact on its cooling capacity; it is necessary to strictly control these components to keep them as close as possible to the designed values. Changes in the composition of the feed gas lead to changes in the cooling capacity required; therefore, it is necessary to adjust the composition of the mixed refrigerant according to the actual conditions in order to ensure an effective balance of the cooling capacity. Monitor changes in the flow rate of the raw material gas: Changes in the flow rate of the raw material gas directly affect the operating status of the cold box. Factors such as the pressure and temperature of the feed to the unit, as well as compressor wear, can all cause variations in the flow rate of the raw material gas entering the cold box. Therefore, it is necessary to closely monitor these factors and make adjustments as needed to maintain the proper operation of the cold box. Adjusting the operation status of the cryogenic tank: By monitoring the temperature difference at the hot side of the heat exchanger and the temperature of the LNG leaving the unit, it is possible to determine the balance of cooling capacity. If the temperature difference at the hot end is large or the temperature of the LNG leaving the plant is low, it indicates that there is an excess capacity in terms of cooling capacity ； Conversely, it indicates that the cooling capacity is insufficient. Based on these indicators, the amount of circulating refrigerant can be adjusted accordingly to maintain a balance in cooling capacity. Adaptation to the composition of the feed gas: The refrigerant ratio must be adjusted according to the composition of the feed gas, and the ratio varies for almost every installation. Even if the proportions of the refrigerant components have been calculated during the design phase, in actual operation it may still be necessary to determine whether adjustments to those proportions are required, based on the cooling effects in each section of the cold box and the operating conditions of the refrigerant compressor. In summary, during normal production, LNG cryogenic tanks can effectively manage the refrigerant by monitoring and controlling the composition of the mixed refrigerant, the flow rate of raw material gases, and adjusting the operating conditions of the tanks, thereby ensuring the safety and efficiency of LNG production.

The ratios used by different patent holders vary

Chromatographic analysis: supplement what is lacking. For the upper and middle sections of the reconstituted mixture, use temperature references; for the lower section, using the product temperature as a reference is sufficient