I have a downcomer from a cryo tower to a Al-Brazed heatexchanger. The downcomer as seen in the attachment is 45 ft tall with 9ft LEG. Tower and HE modeled to apply true displacements on the boundary condition. However, The line is working in two different mode ( Temperature) . When I design for the Mode as shown in the attachment, the expansion loop length of 4 ft will let the load in the HE nozzle within acceptable limit . When I design for Mode 2 , I can not find reduce the forces and moments on nozzle to acceptable limit due to high Moment on the HE nozzle . So my case is good for Mode 1 while when the operation wants to switch to Mode 2 then I would have problem . Can anybody help me on this? Please let me know whatever comes to you mind so I can try that .
P.S: the reason i put expansion loop there is the tower and part of downcomer is existing and I'm connecting to it