The core problem of compressor oper
Discussion on Several Issues of Air Conditioning Cooling Water System
Circulating cooling water treatment
As the scaling, corrosion and algae growth of the air conditioning cooling water system are not formed in a short period of time, and will not have a destructive impact on the system in a short period of time, they often fail to receive sufficient attention from operation and management personnel. In addition, because the air conditioning cooling water system is relatively simple, designers do not pay enough attention to it, and the treatment of cooling water is related to both water supply and drainage majors and HVAC majors, while the cooling water system is mostly done by HVAC professionals. , It is inevitable that the inherent design is unreasonable. In the design process, in view of the fouling and corrosion of the air conditioning cooling water system and the growth of bacteria and algae, the treatment method is also different from that of the chilled water system. Cooling water treatment methods can be divided into chemical methods and physical methods.
(1) Chemical method: At present, large-scale cooling water systems mostly use chemical methods. For this reason, it is necessary to add scale inhibitors, corrosion inhibitors, bactericidal algaecides and supporting cleaning agents to the cooling water, thus forming the cooling water Complete water treatment technology. It can be used as a reference for the design of cooling water treatment for large air conditioners. Since scale inhibition can ensure the heat transfer effect (energy saving), grade corrosion agents, bactericidal and algae-killing agents can reduce equipment corrosion, and extend the life of equipment are all positive benefits. Therefore, it is concerned by the world. Major foreign water treatment companies have adopted this technology as The first key point is that it is reported that the sales value of industrial water treatment agent (cooling water part) in 1987 was 586 million U.S. dollars, and the sales value at the beginning of 1992 was 765 million U.S. dollars, with an annual growth rate of 6. With the rapid development of the national economy, the research and development of water treatment agents has also made considerable progress.
(2) Dosing treatment method: This method has been applied to hot water boilers and ship water treatment earlier. In recent years, this method has also been used in cooling water systems. The commonly used agents are mostly solid crystalline silicate coating corrosion inhibitors. . Practice has proved that there are the following points to pay attention to: different coating agents require different dissolution temperatures. For the dosing on the circulating water system, the water temperature can often reach the dissolution temperature, but for the dosing on the water supplement On the system, special attention should be paid to prevent the water temperature from being too low. If the water temperature is too low, the coating corrosion inhibitor will not dissolve well, which will affect the corrosion inhibition effect.
(3) Physical method: It is a method that has been widely used in recent years. This method has low operating cost, convenient use, easy control, and no pollution. It is an ideal water treatment method. In fact, it was as early as the 1960s abroad. He shifted his attention from chemical methods to physical methods. At present, the applied physical methods include magnetic method, electrolysis method, ultrasonic method, electrostatic method, etc.
The spot solution method can inhibit the adhesion of scale, but the descaling is not complete, and there is a danger of spotting pitting corrosion; the magnetic method used in the early stage has poor stability and cannot control the scale after long-term use. Therefore, it must be cleaned regularly. Iron oxide; and the electrostatic method overcomes the shortcomings of the above-mentioned release methods, and, in addition to preventing enough and dissolving scale, it also has a significant effect of sterilization and algae killing. However, the corrosion inhibition effect of electrostatic method and electronic water treatment method is slightly lower than that of special chemical corrosion inhibition, and other corrosion inhibition methods may not be considered in general air conditioning cooling water systems. In some systems with higher requirements for corrosion inhibition, better results can be obtained by adding some corrosion inhibitors at the same time.
Piping arrangement of cooling water system
Although the piping layout of the cooling water system is relatively simple, some problems may arise if it is not considered properly. Since the circulating cooling water system is an open system, if the volume of the cooling tower catchment pan is small or the cooling tower is too far away from the water pump and the resistance balance of the cooling tower outlet pipes running in parallel is seriously out of balance, the air will be mixed into the water and enter the water pump and press it. Into the pipeline, causing serious water hammer, causing damage to the pump outlet pipe and its fittings. Therefore, the cooling water system should pay attention to the following issues:
(1) When cooling towers are used in parallel, the pipeline resistance is balanced, and the distance between the cooling tower and the pump should not be too far; the pump should be arranged in front of the chiller (that is, the cooling water is pressed into the chiller); and the pump should be self-filling ; Avoid bending up and down of the suction pipe of the pump. In addition, cooling pumps, chillers, and cooling towers should have a one-to-one correspondence to facilitate adjustment and flow balance. If the above-mentioned control cannot be achieved, an automatic control system should be used, and solenoid valves should be installed at the inlet and outlet of the cooling tower, and Should be opened and closed simultaneously. Or set a balance valve on the inlet and outlet pipes of each cooling tower to ensure that the water intake of each cooling tower meets its rated flow. In order to increase the water collection capacity of the suction pipe, the diameter of the suction pipe can be appropriately increased when designing the suction pipe.
(2) When selecting a cooling tower, s* should first pay attention to the gap between the performance parameters given in the product sample and the actual performance of the product. These include factors such as the false product samples and the difference between the meteorological conditions of the project construction site and the test conditions of product calibration performance. It should be checked according to the meteorological conditions of the project site. Ice should take corresponding adjustment measures based on the engineering application experience of the product. Sometimes a larger margin factor has to be used.
(3) Cooling towers are generally installed on the skirts of high-rise buildings. Due to the relatively high distance from the main building, the suction distance of the cooling tower, fire prevention, noise, and floating fog should be considered. The national regulations on the suction distance of cooling towers have made detailed regulations.
(4) When choosing a cooling water pump, it should be determined according to the circulation resistance of the cooling water system, the water delivery height difference and the free head, and it should not be too rich. The flow rate of the pump should be determined according to the temperature difference of the cold water after calibration. When multiple pumps are working in parallel, calculation and verification should be performed according to the parallel curve. Can not blindly superimpose the water volume according to the number of units.
(5) Regarding the collection tank of the cooling water system, in the past when designing cooling water equipment, the volume of the collection tank was mostly set at 10% of the cooling water volume. This requirement is no longer applicable when selecting water-collecting cooling towers. The water collection cooling tower has its own water collection tank, which has a small capacity, but it has been proved to be able to meet the needs of the cooling water pump. The current oil control cooling water system is limited by construction conditions during the day, and most of it cannot be installed with large water collection towers that meet the requirements of 10% cooling water. Therefore, rely on the water collection tank of the cooling tower itself and do a good job of maintaining the water level and making up water. Relevant materials recommend that the volume of the water collection tank is generally 2%-3% of the cooling water volume. The building conditions permit the addition of a pool, and its capacity should not be too large, and it does not need to be set at 10% of the cooling water volume. As long as the water volume of the cooling water system can be accommodated, the normal starting and working of the cooling water pump can be ensured.
