The immersed coil heat exchanger uses a coiled tube as a heat transfer element, which is one of the types of partition wall heat exchangers. According to the different cooling methods of the fluid outside the tube, the coiled tube heat exchanger is divided into immersion type and spray type.
This is an ancient heat exchange equipment. It has a simple structure, convenient manufacture, installation, cleaning, and maintenance, is easy to be anticorrosive, can withstand high pressure, is inexpensive, and is especially suitable for cooling and condensing high-pressure fluids, so it is still widely used in modern times.
Because the volume of the container is much larger than that of the tube, it is bulky, and the metal consumption per unit heat transfer area is large, so the surface heat transfer coefficient of the fluid outside the tube is small. To improve the heat transfer coefficient, a stirrer can be installed in the container.
Tube and tube heat exchanger performance characteristics:
The tube-and-tube heat exchanger has a simple, compact, and inexpensive structure, but cannot be mechanically cleaned outside the tube. The tube bundle of this heat exchanger is connected to a tube sheet, and the tube sheets are respectively welded to two ends of the shell, and a top cover is connected to the top cover, and the top cover and the shell are provided with fluid inlet and outlet connections. A series of baffles perpendicular to the tube bundle are usually installed outside the tube. At the same time, the connection between the tube and the tube sheet and the shell is rigid, while the inside and outside of the tube are two different temperature fluids. Therefore, when the temperature difference between the tube wall and the shell wall is large, due to the different thermal expansion of the two, a large temperature difference stress is generated, so that the tube is twisted or loosened from the tube sheet, and even the heat exchanger is destroyed.
In order to overcome the temperature difference stress, a temperature difference compensation device must be provided. Generally, when the temperature difference between the tube wall and the shell wall is more than 50 ° C, for the sake of safety, the heat exchanger should have a temperature difference compensation device. However, the compensation device (expansion joint) can only be used in the case where the temperature difference between the shell wall and the tube wall is lower than 60-70 ° C and the pressure of the fluid at the shell side is not high. Generally, when the shell-side pressure exceeds 0.6 MPa, because the compensation ring is too thick, it is difficult to expand and contract, and the effect of temperature difference compensation is lost, other structures should be considered.