High-temperature heat exchanger
Thread Content
This post was last edited by kangyusai on 2020-9-22 at 20:35. I’d like to consult the experts: the client wants a DN550 U-tube heat exchanger. For the tube side, the working medium is mainly methane; the design pressure is 7.0 MPA, while the operating pressure is 6.3 MPA. The design temperature is 350°C, with operating temperatures (inlet/outlet) of 40/300°C. For the shell side, the working medium is flue gas; the design pressure is 0.2 MPA, the operating pressure is atmospheric pressure, and the design temperature is 700°C, with operating temperatures (inlet/outlet) of 650/450°C. The client requires that the entire heat exchanger be made of stainless steel. The problem now is that there are no suitable standard container flanges available, and American standard flanges do not come in the DN550 size. Furthermore, extremely high temperatures result in a very low allowable stress for fasteners. I would like to ask the experts: what are the standards that can be used as a reference for designing container flanges? Also, how is the issue with fasteners resolved? This is my first time dealing with such heat exchangers; I earnestly ask for the experts’ guidance!
The operating temperature of the bolt should be determined based on heat transfer calculations, and it should not be set too high.
One has to design the container flange by oneself. Refer to the type of standard flange, adjust the dimensions, and use software for calculation. Where dimensions permit, try to reduce the diameter of the bolt distribution circle; using a larger number of smaller bolts may help lower costs. At such high temperatures, the structure should be fully insulated; it is not advisable to expect heat dissipation to lower the temperature of the bolts.
The fact that it is made entirely of stainless steel means that it is unlikely that equipment flanges can be used; it is recommended to lower the design temperature for the bolts appropriately. It would be best to conduct measurements on existing equipment or use experimental designs
Try to use self-sealing mechanisms to reduce the constraints imposed by fasteners on the design