Cleaning of shell-and-tube heat exchangers is very important after a period of use. Why do we clean shell-and-tube heat exchangers? Generally, due to the stickiness of dust and sediment in the pipe of long-term shell-and-tube heat exchanger used in industry, the heat transfer efficiency decreases, the cost of production increases in disguised form, and the service life of shell-and-tube heat exchanger will be seriously damaged.
1. How to produce fouling in tubular heat exchangers
Tube and shell heat exchanger cleaning, that is, tube and tube heat exchanger cleaning. Because the shell and tube heat exchanger is widely used in industry, the industrial heat exchanger is mainly used for equipment cooling, with large water consumption. At the same time, in order to save water, cooling towers are often set up to circulate cooling water. Cooling water is continuously circulated in the circulating system. Due to the increase of water temperature, the change of water flow speed and evaporation of water, the concentration of inorganic ions and organic substances, the outdoor sunshine of cooling towers and cooling pools, the rain and wind, the entry of dust and other impurities, as well as the structure and materials of equipment, etc. The combination will result in more serious sediment attachment, equipment corrosion and microbial proliferation than the direct current system, as well as the resulting sludge fouling plugging pipelines and other issues. The fouling of heat exchanger is an unavoidable important problem in industrial enterprises.
2. Damage of fouling in shell-and-tube heat exchangers
The application of shell-and-tube heat exchangers in industry after purchase does not mean that they are not concerned, on the contrary, proper maintenance and cleaning have many advantages.
In the production process, many fouls such as coking, oil fouling, scale, sediment, corrosion products, polymers, fungi, algae, sticky mud and so on will be produced in shell-and-tube heat exchanger equipment and pipeline lines. These fouls will reduce the heat transfer coefficient of equipment, reduce the flow area of pipeline or flow resistance. Increased consumption of energy and materials, marked decrease in production efficiency, interruption of process when fouling corrosion is particularly serious, forced shutdown of plant systems, directly causing economic losses, and even possible malignant production accidents. It is almost impossible to completely avoid fouling in today's scientific development. Therefore, the cleaning of shell-and-tube heat exchangers and other equipment has become an indispensable part of industrial production, especially in petrochemical and thermoelectric plants.
3. Cleaning is conducive to improving heat transfer efficiency
After running for a period of time, the surface of shell-and-tube heat exchanger or pipeline often deposits a layer of dirt, which is generally compact and hard, and has low thermal conductivity.
The barrier efficiency of dirt is astonishing, and the organic ions and dust in it may lead to other inevitable problems if they are not paid attention to.
The thermal resistance of fouling is 50-100 times that of low carbon steel and 200-400 times that of copper. So the influence of fouling on heat transfer is very great. After scaling, heat transfer equipment will inevitably affect heat transfer, so that the medium that should be cooled can not be properly cooled, so that the medium that should be cooled can not be properly heated, and the heat transfer efficiency will decline, which will inevitably increase the consumption of heating steam or energy, directly increase the production cost, and affect the safety and normal of equipment. Function. Therefore, heat exchangers should be cleaned regularly to remove dirt and improve their heat transfer efficiency.