Recently, some netizens asked about the operation requirements of lithium bromide absorption refrigeration units, and the following is sorted out by the coldest bacteria today, hoping to help everyone.
(1) Liquid level observation
The level of generators, absorbers and evaporators should be monitored during the operation of the unit, even in fully automatic control units.
1) Always observe the generator level. For the double-effect unit, the liquid level of the high-pressure generator is mainly observed. The liquid level of the high-pressure generator is too high or too low, which will adversely affect the unit and even damage the unit. The reasons for the deviation of the liquid level of the high-pressure generator are: (1) the failure of the solution control valve (especially the valve actuator); (2) Failure of float and float coil; (3) The liquid level setting value is inaccurate, etc. When it is found that the liquid level deviates from the specified value, the cause should be immediately identified and eliminated in time.
2) Always observe the absorber level. The main reasons for the change of absorber level are: (1) the vacuum degree of the unit decreases; (2) Refrigerant water pollution: (3) Improper adjustment of solution circulation, etc. When the external conditions change, it will also cause a change in the liquid level, which is a normal change. When abnormal changes in the liquid level of the absorber are found during operation, the solution sampling and analysis should be carried out in time and the problem should be solved seriously.
3) Always observe the evaporator level. As with absorber level changes, changes caused by changes in external conditions are normal. Under the same external conditions, generally speaking, the refrigerant water level is too high, which is mainly caused by the pollution of the refrigerant water or the poor vacuum degree.
(2) Check the color of the refrigerant water
The color of the refrigerant water can be observed through the sight glass. If the refrigerant water is yellow, it indicates that the refrigerant water is contaminated, and the refrigerant water should be sampled to measure its relative density. If the relative density of the refrigerant water exceeds 1.04, the regeneration of the refrigerant water should be completed.
(3) Observe the outlet temperature of the chilled water
The change of chilled water outlet temperature of the unit should be observed frequently. Changes in the external conditions of the unit and changes in internal factors will lead to changes in the temperature of the chilled water outlet. It is normal for the temperature to rise due to changes in external conditions. However, when there is a significant decrease in the performance of the unit, it is necessary to check the cause of the performance degradation. Possible causes are:
1) Poor air tightness or non-condensable gas in the machine.
2. Refrigerant water pollution.
3) Crystallization.
4) Surfactant failure.
5) Dirt of the heat transfer tube of the unit, etc.
Poor airtightness or the presence of non-condensable gases in the machine are the most common causes. If it is determined that the performance degradation of the unit is caused by poor air tightness, and there is a leak in the unit, try to shut down the unit to detect the leak. If the unit cannot stop running, it can be remedied by increasing the number of pumping times for the time being, but the management of the vacuum pumping system should be strengthened, and efforts should be made to stop the machine as soon as possible to detect leaks.
(4) Observe the cooling water frequently
During the operation of the unit, it is necessary to observe the burst of cooling water, the outlet pressure difference and the temperature difference. If there is a big change, analyze the cause. If other parameters do not change much, it may be due to fouling of the heat transfer pipe or blockage of the heat transfer pipe, or it may be the rupture of the gasket of the partition of the cooling water chamber, which causes a short circuit in the cooling water part.
(5) Observe the fused crystal tube frequently
During the operation of the unit, the management personnel should also frequently check whether the fused crystal is hot. If the molten crystal tube is hot, it means that there is a solution flowing through the molten transistor and the cause should be checked. If it is a precursor to crystallization, it should be treated early. If the molten crystal tube is very hot (the hand can only touch the point, can not stay), it means that the concentrated solution side of the solution heat exchanger may crystallize, and the concentrated solution in the generator can only be bypassed to the absorber through the melt tube.
(6) Pumping out non-condensable gases
At the initial stage of the unit, the non-condensable gas is extracted, mainly to enhance the absorption effect of the absorber, establish stable operating conditions, and prevent the crystallization of the solution. After starting, if the refrigeration capacity does not meet the predetermined requirements, there may be non-condensable gas in the machine, and the vacuum pump should be started to pump the gas, so that the absorption loss of the unit is less than 1.
(7) Do a good job of recording the operation of the unit
The record of the operation of the unit is the reference material for the future operation of the unit. Through the operation record table, you can know the status of the normal operation of the unit, and also find out whether there is any abnormal phenomenon in the operation of the unit. Through the comparative analysis of operating data, it is easy to find out the upcoming faults, and the unit can be adjusted and dealt with in time. Therefore, preventive management can be carried out effectively based on the results of daily examinations. For example, by analyzing the cooling water burst, outlet pressure difference, and temperature difference changes, it is possible to predict the degree of fouling in the heat transfer tube and determine the time to clean the heat transfer tube. In addition, once the unit fails, the operation record is a strong evidence to find out the cause of the failure. In addition, through the accumulation of operating data over the years, it is possible to understand the changes during the service life of the unit so that appropriate treatment measures can be taken.
(8) Other precautions
1) After starting the cooling water pump and chilled water pump, pay attention to the outlet valve of the pump should be opened slowly. Otherwise, too rapid water inlet will cause violent vibration of the pipeline and unit, and even damage the water cover in serious cases.
2) For steam units, before steam is vented to the high-pressure generator, attention should be paid to the drainage of water in the pipeline, and the shut-off valve should be slowly opened to supply heat to the generator. If the heat supply is too fast, the heating expansion is uneven, which is easy to cause serious deformation of the heat transfer tube in the high-pressure generator and the leakage of the expansion pipe.
3) Before the vacuum pump starts, the valve of the unit must be closed, 1-3mn after the vacuum pump starts, and the suction valve can be opened only when the suction pipe is pumped to a higher vacuum.
4) When the temperature of the cooling water inlet is too low and the load is running, it is easy to crystallize, the refrigerant pump is not enough to cause the refrigerant pump to be evacuated, and the refrigerant water is polluted.
5) In case of sudden power failure during operation, the refrigerant pump, solution pump, cooling water pump, chilled water pump, etc. will stop running, and the heat source valve should be closed immediately to stop heating to avoid crystallization of the generator solution.
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