Catalyst mixing tank mltipoint temperature

[Instr13]

Hi,
For preparing catalyst we are using a 7' ID by 9' T/T Carbon Steel mixing tank with agitator at around 30 % height of the vesssel from the bottom. Vessel is vertical. We are going to install temperature element to measure and control the fluid (mixed) temperature at 25 (±5) deg C. A 4" flange available on the head.
1- Do we need a thermowell? or stilling well.
2- What type of sensor (RTD fast response or thermocouple)? and how many element?
3- Should we look into multipoint temperature measurement for this 9' high vessel or averag temperature measurement is enough.
Any suggestion is appreciated. Thanks

 

[dbaird]

Thermowells serve two purposes:
Primary: Used to guard temperature sensor from extreme process pressure, flow and/or vibration.
Secondary: Used to provide isolation of process media while repairs/calibration can be performed without draining the pipe/tank. If the primary purpose is not needed you may still want to install thermowell for the secondary purpose.
I would involve your local temperature sensor supplier if I were you to answer your additional questions. Usually they have access to application engineers that are more then willing to review your needs and source a solution.

David Baird
mrbaird@hotmail.com

Sr Controls Engineer

EET degree.

Journeyman Electrician.

 

[hacksaw]

you need to first define the amount of non-uniformity in your process. having said that, a stirred vessel usually has very good uniformity.

like the previous response recommends, always use a thermowell with insertion measurements.

multipoint is not needed unless you are looking for hot spots or you need redundancy