In heat exchange systems with large temperature fluctuations, if the effects of thermal expansion are not fully evaluated for a fixed tubesheet structure, stress concentration may occur at the connection between the tubesheet and the shell, thereby affecting sealing reliability. The GLC-80 shell-and-tube heat exchanger adopts a fixed tubesheet structure, and the applicable boundaries of its thermal expansion compensation structure need to be judged in combination with specific operating parameters.
Temperature Difference Limits for Thermal Expansion Compensation
The fixed tubesheet structure relies on the rigid connection between the shell and the tube bundle to withstand thermal expansion differences. When the temperature difference between the tube wall and the shell wall is not greater than 50°C, this structural form usually has good adaptability; if the temperature difference approaches or exceeds this range, the additional stress caused by thermal expansion must be calculated during the selection stage, or compensation measures such as expansion joints should be considered. It should be noted that 50°C is a reference limit for structural applicability, and in actual operating conditions, a comprehensive judgment should also be made in combination with medium temperature, flow rate, and environmental conditions.
Comparison of Design Parameters and Operating Curves
The design pressure of the GLC-80 is 1.6 MPa, and the design temperature range is -20 to 200°C. During selection, engineers should compare the actual system operating curve with the above parameters, with particular attention to the temperature fluctuation amplitude during startup and shutdown stages and load changes. Selecting solely based on a single design parameter may ignore changes in the tube-shell temperature difference under transient conditions, resulting in insufficient thermal expansion compensation capability.
Approach for Judging Structural Applicability
To judge whether the fixed tubesheet structure is applicable, a preliminary assessment can first be made based on the design temperature difference, and then the thermal expansion amount can be verified in combination with the operating curve. For operating conditions where the temperature difference approaches the 50°C limit, it is recommended to specify temperature monitoring and stress evaluation requirements in the technical scheme to ensure the sealing performance and structural integrity of the equipment during long-term operation. Parameter selection should be based on actual operating data, avoiding simplified selection that is detached from system conditions.
