Shell and Tube Heat Exchanger Start-up and Shutdown Procedures

Shell and Tube Heat Exchanger Start-up and Shutdown Procedures 

   

  

Shell and tube heat exchangers are designed to eliminate problems from differential thermal expansion of the shell and the tubes.  When the temperature difference between the hot fluid and the cold fluid is large, a removable bundle or a floating head is used to avoid damage from the different thermal expansion rates of the tubes and the shell.

  

For extreme temperature differentials, the metal temperatures should be analyzed carefully.  Mechanical stress calculations should be performed to determine the consequences of any thermal shock on the heat exchanger.

    

In some cases, differential thermal expansion can be a problem at start-up or shutdown.  Many shell and tube heat exchangers have suffered damage during start-up and shutdown because the fluids were not introduced or removed in the proper sequence.

  

The table below offers suggestions on the order in which the hot and cold fluids should be introduced at start-up or removed at shutdown for different applications.

      

  

Exchanger Type	Fluid Location		Start-up Procedure	Shut-down Procedure
	Shell Side	Tube Side
Fixed Tubesheets	Liquid - HOT	Liquid - COLD	Start both fluids gradually at the same time	Shut down both fluids gradually at the same time
	Condensing gas - HOT	Liquid or Gas - COLD	Start hot fluid first, then slowly start the cold fluid.  Avoid temperature shock	Shut down cold fluid first, then hot fluid
	Gas - HOT	Liquid - COLD	Start hot fluid first, then cold fluid	Shut down cold fluid gradually, then hot fluid
	Liquid - COLD	Liquid - HOT	Start both fluids gradually at the same time	Shut down both fluids gradually at the same time
	Liquid - COLD	Gas - HOT	Start cold fluid first, then hot fluid	Shut down hot fluid first, then cold fluid
Removable Bundle u-tubes floating head	Liquid - HOT	Liquid - COLD	Start hot fluid first, then cold fluid gradually	Shut down hot fluid first, then cold fluid
	Condensing gas - HOT	Liquid or Gas - COLD	Start hot fluid first, then cold fluid gradually	Shut down hot fluid first, then cold fluid gradually
	Gas - HOT	Liquid - COLD	Start hot fluid first, then cold fluid gradually	Shut down hot fluid first, then cold fluid
	Liquid - COLD	Liquid - HOT	Start cold fluid first, then hot fluid gradually	Shut down hot fluid first, then cold fluid
	Liquid - COLD	Gas - HOT	Start cold fluid first, then hot fluid gradually	Shut down hot fluid first, then cold fluid