Features and Applications of U-Tube Heat Exchangers

Features and Applications of U-Tube Heat Exchangers

U-tube heat exchanger, each tube is bent into a U-shape and fixed at both ends to the same tube plate, each tube can be freely expanded. Thus solving the problem of thermal compensation, the tube range is at least two courses and the tube bundle can be withdrawn for cleaning. The tubes are free to expand. The disadvantage is that it is difficult to clean the inner wall of the tubes. Tube replacement is difficult and there are few tubes arranged on the tube plate. The advantages are simple construction, light weight and suitability for high temperature and pressure conditions.

Characteristics of U-tube heat exchangers

The U-tube heat exchanger is characterised by a tube bundle that is free to expand and contract without thermal stress due to the temperature difference between the tube and shell, and good thermal compensation performance. The tube course is a double tube course and the process is long. The flow rate is high and the heat transfer performance is good. Strong pressure-bearing capacity, the tube bundle can be withdrawn from the shell. Easy to maintain and clean, and the structure is simple and the cost is cheap. However, cleaning inside the tube is inconvenient and the tube in the middle part of the bundle is difficult to replace. And because the innermost layer of the tube bending radius can not be too small, in the central part of the tube plate distribution tube is not compact. So the number of tubes can not be too many, and the central part of the tube bundle there is a gap. So that the shell process fluid is easy to short circuit and affect the shell process heat transfer. In addition, in order to compensate for the thinning of the wall after the bend, the straight part of the tube needs to use the thicker wall of the tube, which affects its use, only suitable for the shell and tube wall temperature difference is large. Or shell process media easy to scale and tube process media clean and not easy to scale, high temperature, high pressure, corrosive situations.

Application of U-Type Heat Exchangers

U-type heat exchanger belongs to a kind of tube heat exchanger, heat exchanger working principle are heat transfer from the high temperature end to the low temperature section. u-type tube heat exchanger tube process each tube are bent into U-shaped, the two ends of the tube are installed in the same fixed tube plate on both sides. And the head is separated into two chambers by a spacer plate, each tube can be automatically shrunk. Independently of the other tubes and the casing, it is used even when there is a large temperature difference between the casing and the tubes. The actual production of circulating water cooling high-temperature gas will be commonly used U-tube heat exchanger, heat exchanger tube corrosion or leakage can only be replaced after the core, but should not be cleaned.

 Floating head heat exchanger structure, which includes a cylinder, the outer head cover side flange, floating head tube plate, hook ring, floating head cover, outer head cover and silk hole, steel ring and other components. The characteristics are: the inner side of the flange of the outer head cover with concave or trapezoidal sealing surface, and near the sealing surface of the outer side of the hole and set of wire or weld a number of screws evenly distributed. At the floating head, the hook ring and related parts are eliminated, and the sealing groove of the floating head tube plate is the original concave groove and another one is opened at the same end with the centre of the tube plate as the centre of the circle. The radius is slightly larger than the outer diameter of the tube bundle, and the tube plate layering groove is only connected to the trapezoidal groove. It is not connected to the concave groove.

The heat exchanger has multiple layers of material with good thermal conductivity laminated together to form a working principle, similar to that of a water heater The water heater is generated by the heat generated when the gas is burned and the heat exchanger is a medium for generating heat rather than an open flame. Inside the heat exchanger there are two piping circuits, one for the heat source and the other for the heated source. The heat source is like the flame when the water heater burns, such as hot water or steam.

 The heated source is like the water being heated in the water heater and there is also a regulating valve in front of the heat source inlet of the heat exchanger in the heat source circuit. By changing the opening of this valve, the temperature of the heated source can be adjusted. For a jacketed heat exchanger, the structure of this heat exchanger is simple. It is a jacketed layer welded or fitted to the outer barrel of the reactor (or tank), forming a closed space between the jacket and the wall of the vessel. It becomes a kind of fluid passage, when the steam is heated. The steam enters the jacket by the upper receiver and the condensate is discharged by the lower receiver.

 As it is difficult to clean the inside of the jacket, water vapour and cooling water, which are less likely to produce a scale layer, are generally used as heat carriers. The heat exchanger with flat plates and fins as heat transfer elements, it is mainly composed of plate bundles and headers, etc.. There are several channels in the plate bundle, and fins are placed between the two flat plates in each channel layer, and sealed with seals on both sides.

 The thermal fluid channels are placed at different intervals, depending on the fluid flow. B fluid from the inlet head through a distribution section of the guide sheet into their respective plate bundle channel, and then through another distribution section of the guide sheet to the outlet head and lead out. The two fluids are countercurrent between the wall heat transfer, due to the disturbance of the fluid by the fins. So that the boundary layer constituting the thermal resistance is constantly updated, the heat transfer coefficient is generally 3 times that of shell and tube heat exchangers. And in a small temperature difference (1.5 ~ 2 ℃), the heat (cold) recovery effect is good. Compact, as most of the heat is transferred via the fins through the plate, the heat transfer area of the unit volume of the equipment can reach 1500m. Sturdy, but the plate fin heat exchanger channel is narrow, easy to block, cleaning and maintenance is more difficult, the manufacturing process is more complex.