The lithium bromide absorption refrigeration unit uses heat as the power, water as the refrigerant, and lithium bromide solution as the absorbent to produce a cooling capacity higher than 0 oc, which is used as a cold source for air conditioning or production processes. Lithium bromide absorption refrigeration unit is known as a pollution-free refrigeration equipment because of its low power consumption, non-toxicity, pollution-free, explosion-free, safe and reliable. Common problems in unit operation and maintenance
Lithium bromide absorption chiller wintering measures Most of China's steam or hot water lithium bromide refrigeration units often run only one quarter in a year, and most of the rest of the time is in a shutdown state. If the maintenance and repair measures are not taken for the refrigeration unit that is shut down, the damage degree of the refrigeration unit will increase, and the cooling capacity will be accelerated. If the refrigeration unit is likely to be scrapped within 3-5 years, the lithium bromide absorption chiller will be strengthened. Winter maintenance is very necessary to ask questions about lithium bromide refrigerant maintenance.
       After a period of use, the lithium bromide refrigerator often produces scale in the condenser and absorber. The water system breeds algae and then produces slime. The unit has serious corrosion problems, which requires maintenance and repair.
       1. Chemical descaling and cleaning of water circulation system of lithium bromide chiller
       Lithium bromide chillers have two water circulation systems: a refrigerant water system and a cooling water system. The refrigerant water system is generally a closed cycle, and there is almost no loss of water. Therefore, its main problems are rust, breeding of algae, and generation of slime to affect heat transfer. In addition to the above problems, the cooling water system has a problem that the evaporation of water in the cooling tower causes an increase in the concentration of the inorganic salt to cause fouling. Whether it is slime or scale, the heat resistance of the heat exchange copper tube is increased, the heat transfer efficiency is lowered, and the refrigeration capacity of the absorption refrigeration unit is lowered. The data show that when the fouling coefficient of cooling water increases from 0.000086m2K/w to 0.000172mzK/W and 0.000344m2K/W, the cooling capacity of the unit will be reduced by 11% and 26%; the fouling coefficient of refrigerant water will be 0.000086m2K/w. When the temperature is increased to 0.000172m2K/W, the cooling capacity of the unit will drop by about 8%; therefore, the water system should be cleaned and chemically applied regularly. Especially in areas where groundwater is used, the hardness of water is higher, and the phenomenon of scaling is more prominent. Some units will have scales like scales when they are running for several months. It should be noted that the cooling water side and the refrigerant water side of the unit should be carefully cleaned every year during the shutdown period, and various filters, pipes and valves should be cleaned and inspected regularly to ensure good heating effect and circulating water volume. If possible, a filter should be installed at the inlet of the cooling water side and the refrigerant water side to prevent large debris from entering the unit. After the unit is cleaned, in order to prevent the occurrence of scaling again, it is necessary to adjust the management level of the lithium bromide absorption refrigeration unit according to the actual water quality, the preferred formula, and the regular addition of chemical agents.
       2. Internal chemical cleaning of lithium bromide refrigeration unit
       Lithium bromide solution is more corrosive to steel in the presence of oxygen, which is one of the reasons for the higher vacuum requirements of lithium bromide refrigeration units. In addition, the normal maintenance of the unit should be filled with nitrogen to isolate the air, and the maintenance time of the explosion should not exceed 6 hours. The shorter the better. Due to various reasons, once there is leakage, the inside of the refrigeration unit is prone to corrosion, and the generated rust may block the filter and the nozzle. Therefore, it is necessary to adopt a chemical cleaning method to clean and maintain the inside of the refrigeration unit.
       3. Regeneration of lithium bromide solution
       The pH of the lithium bromide solution, the pH value and the concentration of the lithium chromate corrosion inhibitor should be checked periodically during maintenance. When the lithium bromide refrigeration unit is operated for a long period of time, a large amount of precipitates and chromium compounds are easily formed in the solution, which reduces the refrigeration efficiency of the unit and reduces the refrigeration capacity of the refrigeration unit. Therefore, it is necessary to regenerate the lithium bromide solution to increase the cooling capacity, reduce the equipment failure rate and extend the service life of the unit. The regeneration method of lithium bromide solution has the following L5J:1 The solution is taken out from the unit, placed in a large container, and the supernatant liquid in the upper part of the container is sucked up by the sediment, and the residual liquid sinking at the bottom is discarded to achieve the purpose of removing the sediment (but The solution is exposed to the atmosphere for a long time);
Filter the solution using a filter (but the solution is exposed to the atmosphere for a long time);
       A regenerative device is installed in the refrigeration system to enable the dirty lithium bromide solution to be regenerated under vacuum conditions in the refrigeration system, and to fully utilize the functions of the original equipment in the refrigeration system. It is convenient to use, saves time and is effective, and can regenerate the solution at any time to remove sediment. To ensure a smooth circulation of the solution.
In the internal chemical cleaning and regenerative treatment of the lithium bromide refrigeration unit, the following points should be noted: Each shielding pump and filter should be disassembled and cleaned during the washing process after the pickling process to remove impurities from the filter screen;
The use of passivated water instead of phosphating is mainly due to the fact that not only the iron material but also the copper material in the unit, the charge of the passivation solution should be more than the normal filling of the unit;
       Chemical agents have certain pollution to the environment. Recycling should be recycled as much as possible. Discharge should be done.
Use chemical agents, pay attention to safety during the operation, take necessary protective measures, and be operated by a full-time staff.
       4. Treatment of heat transfer tube rupture
       The evaporator heat transfer tube often freezes during the operation of the refrigeration unit. This is when the refrigerant water of the system is broken, the operator fails to find it in time, and the refrigerator continues to operate, so that the temperature of the refrigerant water accumulated in the heat transfer tube of the evaporator Continue to drop until the ice is frozen and the tube is cracked. The heat transfer tubes of the refrigeration system may be cracked, which may be one or several when it is slight. In severe cases, dozens or hundreds of simultaneous cracking may occur, resulting in large economic losses. Special attention should be paid to the operation of the unit. . The fundamental measure to avoid the freezing and cracking of the heat transfer tube is to strengthen the operation management. During the operation, the engine room duty personnel should observe the changes of the relevant operating parameters from time to time. Once the abnormal signs appear, for example, the system protection device acts due to the water shortage of the refrigerant water, and the alarm bell rings. Wait for the situation, immediately turn off the heating. When the heat transfer tube is broken, since the refrigerant water has been filled into the machine, the concentration of the lithium bromide solution drops sharply, and at the same time, the vacuum degree of the refrigerator decreases, and the refrigeration capacity disappears. Therefore, if there is an accident of heat exchanger tube rupture, professional repair or repair department should be professionally repaired.
However, before the repair, it is necessary to take the initiative to isolate the air leakage from the machine, and seal the leak to the ambient air.
       5. Maintain vacuum
       The lithium bromide absorption chiller works under high vacuum. The absolute pressure in the evaporator and absorber is only a few millimeters of mercury. The external air is very easy to vent, and non-condensable gases are inevitably generated during operation. Even a very small amount will greatly impair the performance of the unit. After adding 3Og of nitrogen (G = 9.5%) to a unit with a cooling capacity of 2267.85 kW, the cooling capacity is reduced by half to only 1163 kW. Moreover, as the non-condensable gas increases, the performance of the unit will be completely destroyed and will not operate normally. Therefore, the degree of vacuum is an important parameter to measure the performance of the refrigerator. In order to operate the unit normally, the unit vacuum must first be guaranteed. Whether it is running or shutting down, the degree of vacuum should be regarded as the lifeline of the unit, and the machine must be checked. A qualified and excellent refrigerator requires an absolute pressure of 30 Pa and a pressure rise of no more than 20 Pa for 24 hours. If it does not, it must be checked. If the nitrogen filling maintenance also requires the purity of N2. Only in this way can the unit's corrosion and cooling performance be reduced.