For a shell-and-tube heat exchanger, the operating temperature in the tube side is 300 degrees with a pressure of 10 MPa, while the temperature on the shell side is 50 degrees with a pressure of 0.6 MPa. What are the design temperature and pressure for the shell?
Thread Content
For a shell-and-tube heat exchanger, the operating temperature in the tube side is 300°C with a pressure of 10 MPa, while the temperature in the shell side is 50°C with a pressure of 0.6 MPa. What are the design temperature and pressure for the shell? How to determine the design temperature and pressure for the shell side – is it the temperature increased by 15–30°C? Should we still go with the high-temperature side? Is the pressure the design pressure of the low-pressure side, or should it be 2/3 of the design pressure of the high-pressure side? Seek standards or criteria
In your case, I think it’s sufficient for the shell design temperature to be no lower than the highest temperature in the tube side, and the pressure to be no lower than the highest pressure in the shell side.
In such cases, standard engineering companies design it as follows: the design temperature for the shell side is the highest operating temperature plus 20°C, while the design pressure is set at 0.8 times the design pressure of the tube side.
Hello, does the maximum operating temperature mentioned here refer solely to the shell side, or to the highest temperature in both the shell and tube sides? Thank you; could you please provide this standard number?
The maximum operating temperature referred to here is that of the shell side. The determination of the design pressure is primarily based on the following reason: In heat exchangers where the operating pressure on the high-pressure side is more than 1.25 times that on the low-pressure side, if no special measures are taken to enable the low-pressure side to withstand sudden increases in pressure resulting from the rupture of the heat exchange tubes (such as the installation of safety valves or burst disks), then the design pressure for the low-pressure side should not be less than 0.8 times the design pressure of the high-pressure side. In the petrochemical industry, most substances are flammable and explosive; this is the standard practice for safety reasons. Generally, these are specified in the design regulations at the beginning of a design project. No national or industry standards have been established. My opinion is for your reference only!
The design pressure on the low-pressure side of the heat exchanger should be 2/3 higher than that on the high-pressure side; this is presumably a requirement for setting up safety valves. HG20570 specifies relevant requirements for the installation of safety valves； Under normal circumstances, the cold and hot sides of a heat exchanger need to be determined based on the actual temperature and pressure ； It is indeed difficult to determine the conditions under which the heat exchange tubes in a heat exchanger’s safety valve fail. The discharge function of the safety valve also presents a problem. In the past, to avoid installing safety valves, people would artificially increase the design pressure on the low-pressure side. However, fundamentally, the failure of the heat exchange tubes is caused by vibration, and it has little to do with the design pressure of these tubes. Therefore, even if the pressure on the low-pressure side is increased artificially, it is still not possible to prevent the tubes from failing. At this point, it is also necessary to consider whether raising the pressure on the low-pressure side to 2/3 is sufficient