Condenser descaling: Which is better, tube brushes or rubber balls?

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A fully automatic online cleaning system refers to the process of cleaning the inner walls of the heat exchange tubes in the heat exchanger as the system operates, without shutting down the chiller unit. The fully automatic cleaning systems available on the market are mainly divided into two types: one is the fully automatic tube brush online cleaning system, and the other is the rubber ball online cleaning system. http://sucimg.itc.cn/sblog/o4bbb670016469856d5ce11797a37735f http://sucimg.itc.cn/sblog/j05f34cee7f8d9ec47303fb5b206e4b93 What are the differences between the tube brush and rubber ball cleaning systems? 1. There are two obvious differences between tube brushes and rubber balls: (1) Tube brushes can clean each heat exchange tube ； The cleaning by the rubber ball system is a probabilistic process; typically, the rubber balls move along with the water flow to scrub the condenser tubes. In areas of the condenser where the flow velocity is high, more rubber balls pass through, while in areas around the periphery where the flow velocity is low, fewer balls pass through. In some condenser tubes, no ball passes through for several days. If scale builds up inside such tubes, the arrival of balls can cause them to get stuck. (2) The bristles of the pipe brush are of spiral structure, allowing them to move forward in a spiral manner to clean the threaded grooves ； The gel ball cannot clean the grooves, making it more suitable for light tubes. 2. Threaded heat exchange tubes cannot be cleaned using an online rubber ball cleaning system, as the wear rate of these balls is relatively high; the debris formed after the balls are worn tends to mix with them and get stuck inside the tubes. Only plain tubes can be used for this purpose. To clean such heat exchange tubes, a fully automatic tube brush online cleaning system should be used! 3. Glue balls turning into mud balls usually occurs in areas with hard water quality; in regions with soft water quality such as the south, it’s not necessary to take the balls out for cleaning every six months, and they won’t get clogged ； But in northern regions, it should be taken out for cleaning at least every 2 weeks; otherwise, the sponge ball will become clogged with sediment, losing its elasticity and getting stuck in the condenser tubes. The pipe brush has worked fine for five years. 4. When the heat exchange tubes are standard 3/4 size tubes, the minimum allowable flow velocity inside the tubes of a gel ball system is 1.7 m/s; gel balls should not be used when the flow velocity is below 1.7 m/s ； The rubber ball system is not suitable for applications where the cooling water flow rate varies; these two points represent the limitations of the rubber ball system in central air conditioning systems. Most customers of central air conditioning systems use variable frequency technology throughout their cooling water systems in order to save energy (including the pumps used for supplying cooling water). The flow rate of the cooling water changes depending on the external temperature. When the flow speed is less than 1.7 m/s, if a rubber ball system is still in use, ball jamming can occur; moreover, when the operating pressure of the cooling water pump is less than 2 kilograms, it becomes easier for the balls to get stuck. Therefore, the flaws of the gel ball system are obvious. 5. When there are heat exchange tubes of two or more different sizes in the central air conditioning condenser (for example, large and small tubes in a York machine’s condenser), a gel ball system cannot be used ； The brushes of the tube brush system can be customized according to the size of the heat exchange tubes. 6. If the partition in the water chamber of the air conditioner’s condenser blocks some of the heat exchange tubes, the gel ball system will definitely get clogged; in such a case, it is sufficient to install tube brushes only on those heat exchange tubes that are not blocked, and this will not affect the flow of water or the heat exchange in those tubes. 7. The corrosion and scale inhibition agents as well as bactericides added to the circulating cooling water can reduce the elasticity of the rubber balls, diminish their scrubbing efficiency, and even make them sticky, causing them to adhere to the heat exchangers. This situation has already occurred in many customer systems in the southern regions. 8. The problem of balls getting lost in the ball-cleaning systems persists; whether it is the ball-cleaning systems used in power plants or those in air-conditioning systems, no such system anywhere in the world has ever managed to recover 100% of the balls. In some cases, the balls get stuck in the eddy current areas due to the complexity of the water circuits, while in other cases, rust or welding slag within the system hinders the movement of the balls. After cleaning with bubble washing, the threads of some condenser tubes may develop burrs, and these burrs can easily trap the balls. Therefore, in a ball-trapping system, a recovery rate of over 90% is considered very high; most systems fail to achieve such a recovery rate. 9. The disadvantage of the pipe brush system is that it can only be used on straight pipes, not on U-shaped pipes. However, the recovery rate of the rubber balls using a rubber ball system in U-tubes is also lower, especially when the rubber balls submerged in water are 1 mm larger than those in the condenser tubes, resulting in greater pressure loss and making it difficult to retrieve the balls. 10. When using the pipe brush for the first time, it is necessary to install the brush basket, the four-way directional control valve, and the control unit ； When using the rubber ball for the first time, it should be submerged in water and the air inside the ball removed by hand; otherwise, due to the air inside, the rubber ball will float on the surface of the water and will not easily enter the condenser tube. 11. Some air conditioning units are equipped with frequency converters, and the cooling water for these frequency converters comes from a branch taken from the cooling water of the air conditioning unit itself. If no (tapered) filter is installed in this branch, debris can enter it, thereby blocking the water inlet of the frequency converter and preventing its temperature from dropping. 12. Using a tube brush can ensure the heat exchange efficiency of the heat exchanger ； During the cleaning process, the gel balls can increase the heat transfer rate by 5%; however, if the balls get stuck, they lose their ability to dissipate heat. Beijing Huayanbang’s fully automatic tube brush online cleaning system evolved from the rubber ball system. The obvious difference is that the tube brush system performs cleaning in a \"forced\" manner; that is, a cleaning brush is installed inside each copper tube to ensure that every tube is effectively cleaned during operation, resulting in low frictional resistance. The dirt removed is carried away by the water flow at a normal speed, so the friction during the cleaning process does not change. The cleaning brush moves smoothly at a low speed; the minimal wear ensures a longer service life for the brush, which only needs to be replaced every 5 years. This also helps to protect the corrosion-resistant layer on the surface of the pipe wall. The alternating direction of water flow during cleaning makes clogging almost impossible.