Tube heat exchanger

Tube heat exchanger is two sizes different from standard pipe connection concentric tube, called the shell outside, the interior is called the tube. Two different media can reverse flow (or in the same direction) in the shell and tube heat exchanger in order to achieve results. Structure and principles in a concentric sleeve inner tube heat exchanger as a heat transfer element. Two different diameter tubes together to form concentric sleeve casing, each casing section called "one-way" process of inner tubes (heat transfer tubes) by U-shaped elbows, short tube in turn connected to the outer tubes in a row, fixed to the bracket (figure a). Heat transfer through the inner tube wall from one fluid to another fluid. In general, thermal fluid (A fluid) introduced by the upper, and the cold fluid (B fluid) introduced by the lower part. FOREIGN casing pipe ends with the tubes welded or flanged connections. U-shaped inner tube and multi-flanged elbow, easy cleaning and decrease the heat transfer tubes. The effective length of each heat transfer tube to take 4 to 7 meters. This heat transfer area of ??up to 18 meters, it is suitable for small-capacity heat exchanger. When the temperature difference between the inside and outside wall is large, it can be set between the outer tube U-shaped expansion joints (figure b) or the inner and outer tube using stuffing sliding seal (Fig. C), to reduce the thermal stress. The tubes can be of steel, cast iron, ceramics and glass is made, if the selection properly, it can be used in corrosive medium heat. The advantage of this heat exchanger has several outstanding advantages, so is still widely used in petrochemical and other industrial sectors. ① simple structure, increase or decrease the heat transfer area freely. Because it is made of a combination of standard components, installation without additional processing. ② high heat transfer effectiveness. It is a pure countercurrent heat exchanger, and can also select the appropriate cross-sectional dimension, to increase the velocity of the fluid, increasing the heat transfer coefficient on both sides of the fluid, and therefore its good heat transfer. Liquid - liquid heat exchanger, the heat transfer coefficient of 870 ~ 1750W / (m 2 · ℃). This is particularly suitable for high pressure, low flow, low heat transfer coefficient of heat transfer fluid. Shortcoming tube heat exchanger is large area; metal consumption per heat transfer area and more, shell and tube heat exchanger is about 5 times; fittings more easily leak; flow resistance. ③ simple structure, large work adjustment range, easy to increase or decrease the heat transfer area, both sides can increase the flow rate of fluid, so that both sides of the heat transfer surface can have a higher heat transfer coefficient; drawback is that metal consumption per heat transfer surface capacity, maintenance, cleaning and demolition are more trouble in the detachable connection is likely to cause leakage. To increase the heat transfer area, improve heat transfer effect, plus the inner tube wall provided various forms of fin, and Canada set up scraping the inner tube membrane perturbation means to adapt to the high viscosity of the fluid heat transfer.