Comparison of heat exchanger cleaning technologies

Thread Content

This post was last edited by liaifeng on 2020-3-19 at 20:04. Comparison of common cleaning techniques: Various cleaning challenges arise during the cleaning of heat exchangers. On the one hand, these challenges hinder the improvement of corporate economic efficiency; on the other hand, they drive the development of cleaning technologies, leading to the emergence of numerous different cleaning methods. However, many cleaning techniques are quite specific and not suitable for widespread adoption. Currently, the commonly used heat exchanger cleaning techniques include high-pressure water cleaning, mechanical cleaning, and chemical cleaning. These three types of cleaning methods are highly applicable to the cleaning of heat exchangers. 1. High-pressure water cleaning: High-pressure water jet cleaning is a technique that uses a high-pressure water generator to take advantage of the mechanical energy and physical properties of water in order to remove dirt from heat exchangers. Compared to traditional water jet cleaning, high-pressure water jet cleaning technology makes more efficient use of the physical properties of water; it possesses greater impact force, yields better cleaning results, and is more widely applied. Advantages of high-pressure water cleaning: a. Fast speed and high efficiency. Through a series of crushing actions such as the shear erosion caused by high-pressure water jets, the hard fouling on the heat exchange surface is instantly broken apart and carried away by the water flow, resulting in a cleaning speed that is several times to dozens of times faster than that of traditional cleaning methods. b. Low cost and low water consumption. High-pressure water jet cleaning generally uses tap water as the cleaning medium. Due to the high kinetic energy of the high-pressure water jets, they are fully capable of cleaning heat exchangers thoroughly, so there is no need to add any additional abrasive agents or cleaning chemicals. The cleaning nozzles of high-pressure water jet cleaning vehicles generally have a diameter of less than 2 mm, enabling fine jet spraying and reducing water consumption. c. It does not corrode equipment nor pollute the environment. High-pressure water jet cleaning uses tap water as the cleaning medium, taking advantage of the physical properties of water to cut and break down the dirt on heat exchangers. The entire process is a purely physical phenomenon, and it does not cause any chemically corrosive damage to the materials of the heat exchangers. d. It has a wide range of applications. The high-pressure water jet cleaning nozzle is compact and flexible; it can rotate automatically in two and three dimensions, ensuring thorough cleaning. It has no special requirements regarding the equipment or the dirt to be cleaned, and it can clean areas with complex shapes and structures as well. Therefore, it is widely used. e. High security. It can be used in flammable and explosive environments. f. The cleaning quality is relatively good. The jet pressure of high-pressure water is lower than the compressive strength of metals, allowing it to easily break down hard layers of dirt without damaging the material of the heat exchanger; after cleaning, the natural metallic color of the material can be seen. g. High-pressure water jet cleaning is suitable for completely blocked pipes; it offers good cleaning results for those cases that are difficult to clean manually or involve hazardous conditions, and it is easy to mechanize and automate. The main disadvantages of high-pressure water cleaning are as follows: during the cleaning process, the strong impact force generated by high-pressure water causes the equipment being cleaned to vibrate, resulting in significant noise pollution; moreover, its effectiveness in removing dirt with high viscosity is not very good. 2. Mechanical cleaning: Mechanical cleaning is a technique that uses mechanical tools to clean equipment through methods such as scraping and vibration. The principle and operation of mechanical cleaning are relatively simple. Its advantages include: it is effective at removing dirt with high viscosity and hardness; it does not cause corrosion to heat exchangers; it results in minimal wear on the cleaning equipment; it is pollution-free; and it offers high safety levels. The main disadvantages of mechanical cleaning are: the equipment must be disassembled; the cleaning process is time-consuming and costly; it is not effective for quickly removing debris, resulting in low efficiency; sometimes the system has to be shut down before cleaning can take place; the cleaning is not thorough enough and it can easily scratch the pipe walls. 3. Chemical cleaning: Chemical cleaning is a cleaning technique that makes use of chemical agents to induce chemical transformations or dissolutions through chemical reactions or principles such as like dissolves like, thereby reducing the adhesion between the heat exchange surface and the fouling, and thus removing the fouling from the surface. The complete chemical cleaning process mainly involves penetration, dispersion, and dissolution. Advantages of chemical cleaning: a. There is no need to disassemble the equipment; especially for shell-and-tube heat exchangers that cannot be taken apart, chemical cleaning offers advantages that mechanical cleaning cannot match. b. It can clean every corner and tiny gap of the heat exchange surface, providing a thorough cleaning that prevents undissolved scale particles from remaining and thus forming new sources of dirt. c. The cleaning method is relatively gentle and does not cause any physical damage to the heat exchanger material, something that mechanical cleaning cannot achieve. d. After cleaning, anti-rust and passivation treatments are carried out to prevent rusting of the equipment following cleaning. e. It requires little manpower and resources, and can be cleaned on-site or online, resulting in lower labor intensity. f. The waste liquid after cleaning can be recovered through distillation or reprocessing, or it can be separated by adding demulsifiers, thereby effectively reducing pollution emissions. g. Generally not restricted by time or space, **reducing the workload associated with shutdowns for maintenance. The limitations of chemical cleaning are as follows: generally, a fluid circulation system needs to be established, and it is not suitable for equipment that is severely clogged with dirt; various factors must be taken into strict consideration during the cleaning process, as even the slightest carelessness can lead to unexpected corrosion of the equipment; the waste liquid resulting from cleaning must be treated before it can be discharged; and the cost is relatively high.