I. Analysis of lithium bromide solution
The lithium bromide solution circulates in the bromine cooler, which is corrosive to the metal, and will cause strong corrosion to metal materials such as steel plates and copper pipes in the presence of air leakage. After the corrosion is generated, not only the life of the bromine cooler is greatly shortened, but also the hydrogen and copper iron ions generated by the corrosion will directly affect the normal operation of the unit.
The main cause of corrosion inside the absorption refrigerant is due to the deterioration of the vacuum degree of the bromine refrigerator. Although a corrosion inhibitor is added to the solution, a protective film is formed on the surface of the metal to reduce the occurrence of corrosion, but it can only be delayed, and corrosion cannot be prevented. During the corrosion process, copper-iron ions are slowly released and dissolved in the solution. As the solution circulates in the machine, it is gradually deposited in a low-temperature heat exchanger with a low flow rate and a low position. The heat exchange effect is poor, the flow rate is reduced, and the concentration is increased to cause crystallization, which makes it impossible to work. In addition, some impurities are blocked on the filter screen of the absorption pump, which will affect the pump's own cooling and lubrication, and shorten the life of the pump.
The quality of the lithium bromide solution can be identified by chemical analysis by visual inspection and sampling. When the solution is visually observed, the good solution is a colorless and transparent liquid, which is charged into the bromine cold machine. Due to the light, it is brown from the sight glass, and the poor solution becomes a fine crystal due to the entry of Gu and Fe. The solution was seen to be dirty from the sight glass, and there was foreign matter on the electrode rod, and the solution was yellow in color.
The most scientific method for determining the solution is to collect the solution back to the manufacturer, analyze its composition, and determine the operating state of the bromine cooler by adjusting its composition and adjust it. The sampling test of the solution is once a year.
Second, the management of lithium bromide solution
1. Corrosion inhibitor (Li2MoO4)
Corrosion inhibitors decrease with the running time of bromine cooler. If the standard value is not reached, please add it by the manufacturer. If the bromine cooler is operating normally, add it once every 2-3 years.
2, pH
The heat exchange tube of the bromine cooler is composed of a copper tube, and the copper is characterized by alkali resistance and acid resistance. Therefore, the lithium bromide solution is alkaline, with a pH between 9 and 10.5. During the operation of the bromine cooler, the alkalinity of the solution is corroded by the solution, and in order not to corrode the copper tube, the bromine cold life is prolonged, and the alkalinity is adjusted based on the chemical analysis.
3, isooctanol
Isooctanol is a liquid surface active agent that reduces the tension on the surface of the liquid and changes the way the refrigerant evaporates. Thereby reducing the volume and increasing the amount of cooling. Due to its volatility, it is easy to be discharged to the outside of the machine during the pumping operation, so it is necessary to add it at regular intervals.
4, copper and iron ions
The bromine cooler is mainly composed of copper and iron. Due to the corrosive action of the solution, the ions will dissolve into the solution. As the running time increases, the dissolution of the ions will increase, which will affect the normal operation of the bromine cooler. Therefore, the solution must be filtered, and the manner of filtration varies depending on the degree of turbidity of the solution.
Continuous filtration
A filter is connected between the auxiliary valve of the dilute solution pump of the bromine refrigerator and the auxiliary valve of the concentrated solution, and the filter element is a molecular sieve and activated carbon. The filtration time is relatively long and the effect is obvious.
b. Off-board filtering
The whole solution is discharged to the outside of the machine, and it is packed in a plastic vat, and then filtered by a filter, and the effect is obvious. The time is short, but the workload is large and the operation is complicated. It is used in the overhaul of bromine cooler.