3 replies to this topic

[process equipment]

Dear all,

I have a general question, since there are no standards:

Is it OK to install thermowell or measurements attached in the nozzle or in the pipe line for heat exchangers. What are the advantages and disadvantages and the influence.

Regards,

PE

[djack77494]

Personally, I like to have nozzles available for possible thermowell installation at all four process connection; i.e. Tubeside in & out and shellside in & out. If there are multiple nozzles at any of these locations, I like to have connections at each. I might go no further for streams where the properties are well known. For example, if I have 50# saturated steam going to a heater, and especially if I have header pressure and/or temperature measurements, nothing else is needed. I do like to install thermowells in the nozzles for all outlets and inlets when the temperature may be in doubt. The cost is quite low, but if you need to troubleshoot a problem or even to just analyze the performance of youyr equipment, these could prove invaluable.
Doug

[process equipment]

Dear jack,

tnx for your reply.

You are saying that the measurements devices can be normally installed in the nozzles and it is cheaper than installing in the process lines (let say max 1 m distance from the nozzles). The idea is if the thermowells is installled in the nozzle ( at the inlet for instance ) there might be some flow disturbances at the inlet. I guess the inserted length is 0.75* OD pipe. Does this has any negative effect on the inlet flow distribution in which it might have some influence on the performance ? The idea of installing at a small distance from the nozzle is to overcome this problem, while keeping the temperature gradient very small. Indeed you are correct, if there is some doubt about the temp. the measurements should be installed at the in/out nozzles. However mechanical engineers oppose to that because it is not convenient and there is no available space. Is there any problem to locate the thermowells in the process lines for gas and / or liquid phase ?

Please advice

PE

[pleckner]

There should be no reason you can't put the thermal wells on the process piping. The plants I've designed do this much more often then putting them right on the nozzles.