During on-site commissioning, a common situation often arises: with the same process flow, two shell-and-tube heat exchangers with similar parameters—one maintains stable tube-side pressure drop and controllable outlet temperature, while the other experiences a rapid rise in shell-side pressure differential and a gradual deviation of temperature difference from the design value after the medium flow rate is increased. After disassembly and inspection, it is often found that there is fouling on the tube bundle or short-circuiting in the baffle area. The problem does not lie in the strength of the equipment itself, but rather in the misalignment between the basic data of the hot and cold side media and the structural selection. The significance of comparative analysis lies precisely in identifying such deviations at the selection stage.
When comparing different schemes, technical engineers are advised to first record separately the chemical name, mass flow rate or volumetric flow rate, inlet and outlet temperatures, working pressure, and allowable pressure drop of the hot-side and cold-side media. These data directly determine the flow velocity ranges of the tube side and shell side, as well as the tube bundle layout and baffle spacing. When the chloride ion content of the medium exceeds 200 mg/L, it is recommended to use a duplex steel tube bundle to reduce the risk of pitting corrosion and stress corrosion; if the cleanliness of the medium is low, the cleaning method and maintenance space should be included in the comparison rather than comparing only the heat transfer area.
The scheme in which the corrosive medium flows through the tube side and cooling water flows through the shell side facilitates the overall extraction and cleaning of the tube bundle; conversely, when dirty medium flows through the shell side, fouling easily accumulates on the back of the baffles, resulting in higher maintenance intensity. During comparison, attention should be paid to the matching relationship between the number of tube passes and the shell diameter. Increasing the number of tube passes can raise the flow velocity, but the pressure drop will increase accordingly, which needs to be checked against the allowable pressure drop. The heat transfer area, tube-side and shell-side materials, tube specifications, and arrangement should be compared as a set of parameters as a whole; simply enlarging the area alone does not necessarily improve the heat transfer effect.
This equipment is suitable for liquid and gas heat exchange applications in chemical, metallurgical, power, and other systems, and can operate continuously under medium and low pressure conditions. During operation, the fluctuation range of medium temperature and pressure should be controlled, the connection between the tube bundle and the tubesheet should be inspected regularly, and the cleaning cycle should be scheduled according to water quality conditions.
