3 replies to this topic

[gtoutounji]

Hi,

I am designing a movable jacketed mixing tank for slurry of 1000 working volume. Tank is from stainless steel, dish bottom with open top and is moved to the mixing station for agitation. Where is the best location of the thermowell or temperature sensor? Batches vary from as little as 300 liters to 1000 liters. Product is viscous and range from 200 cps to 10,000 cps. Can I mount the sensor close to the discharge at the center of the tank, the reason being that the product has tendency to heat up at the center due to bad cooling from the jacket.
The same question applies for the pH sensor.

Thank you.

[Erwin APRIANDI]

Hi gtoutounji,

From my point of view it will be depend on your requirement
if you required to see the maximum temp and pH location at bottom centre would be ok
but if you required to know the average value of temp and pH, I would recommend to have it
at middle section between the tank centre to side wall

Please refer to the enclosed sketch for detail

Attached Files

•  Tank Sketch.xls   16KB   57 downloads

Edited by erwin.apriandi, 08 August 2011 - 01:04 AM.

[kkala]

The temperature sensor has to be placed lower than 300/1000 of the tank height (tangent to tangent).
Agitator(s) are assumed vertical, inserted ftom vessel top. Sensor had better be below agitators' impeller level, to avoid any "meeting" between them, even inadvertedly.
Liquid discharge is understood to be at the center of dish bottom. In case you operate a single vertical agitator, placing the sensor a bit off center may be better. Area just below impeller can be somehow stagnant (as I imagine from the streams developed during agitation and seen in book sketches); partial volume to some angle down from impeller can be more "vivid" to result in more representatitive temperature.
Above under the assumption that max slurry temperature has to be measured. PH sensor can be located at same point.
A sketch of tank and agitator(s) would be helpful. At any case this is an opinion not based on some practice or standard. Other views would be interesting to read.

Edited by kkala, 08 August 2011 - 11:55 AM.

[gtoutounji]

Hello and sorry for the late reply,

Thank you for all the informative answers. I have relocated the temperature sensor to be mounted at the side just at the lower tangent where the shell meets the dish. The reason is to have easy plugging and unplugging the sensor from the cable coming from the transmitter as the tank is a movable one. Also, the tank has three baffles that extend down to the same height as the location of the sensor. The tank is jacketed with cooling water. Is that a good location? Any issues? There were in the past issues with product overheating.

Thank you,