3 replies to this topic

[Sue N]

While I have been a process engineer for 16 years, I am new to natural gas processing and brazed aluminum heat exchangers (BAHX).  I work for a company that uses BAHX in their distillation processes. 

 

I am reviewing the design of a proposed distillation process and had some questions about the relief device scenarios for a BAHX.  Specifically, I am trying to find information about the scenario of a leak of the heat exchanger surface. ( By contrast, I can easily find guidelines and calculations for a tube rupture case for a shell and tube exchanger. )

 

1.  Are there guidelines for BAHX that determine if a leak of the heat exchanger surface is a credible scenario?

 

In the processes I am involved in, the hot and cold streams into the BAHX are chemically similar - there would be no chemical reactions should the hot and cold fluids become mixed.   Also, mercury poisoning would not be an issue with our chemicals.  

 

2.  If it is a credible scenario, are there any recommended calculations to use?  

 

In most cases, the pressure ratings of the equipment are such that a leak would not cause hazardous over-pressure of downstream equipment, but I already found at 2 pieces of equipment that could be at risk should a leak occur.  I am not sure if specifying higher pressure ratings for these pieces of equipment is economically feasible.

 

Thank you for your help.     

 

 

 

 

[CMA010]

We usually assume a 1mm split along a parting sheet brazed joint inside the inlet or outlet header box. As a header box encapsulates both high and low pressure passages potentially a split can occur along a high pressure passage joint, leaking into the low pressure header box.

[ColinR33]

We do similar to what CMA indicates. We also talk to the BAHX manufacturer to see what recommendations they have with regards to size of the split.

[Sue N]

Thank you both for your assistance.