Hi Pong,
Here is the more detailed explanation about problem:
We have a rawmaterial called surfactant is one of the major ingredient in detergent making. RM is stored outside building and open to atmosphere. The raw material need to be maintained b/w 70 to 120 F. if temp is out of these limits material will be not useful to process. So, it is directed from business unit 72 F is best to the process.
Due to some business reasons, we are not allowed to work on tank modification or agitator installation over the tank. There is no further discussion on providing agitator and any other system.
We have got only option that provide a plate type heat exchanger and maintain proper re-circulation to ensure uniform and required temp across the tank. But, material is bit viscous to achieve uniform temp with out agitator.
SO, the challenge is to find optimum re-circulation rate.
I have listed below material properties, operating conditions, ambient conditions, tank geometry.
Material off spec limit: 70 to 120 F
Operating temp: 72F to 105F
Material properties:
spec gravity @105 F: 1.0125
specific heat at 105 F: 0.433 btu/lb.F
thermal conductivity @105 F: 0.091 btu/hr.ft.F
Viscosity data:
@60F-310 cp
@70F-248cP
@90F- 158 CP
@105F-90Cp
Material inlet temp: 60F
Outlet temp needed: 72F
Tank total working vol:8000 USgallons
material unload from truck and truck vol: 5000 us gal
Ambient temp: 0F
wind speed: 11 mph
Tank dia: 15 ft
shell ht: 16 ft
Total heat transfer area: 1143 ft2
Tank is flat bottom and resting on concrete pad (there is no legs)
MOC of tank: tank has two layers: inner 3/16 inch thick ss316L, outer layer 1/4 inch CS
Tank got insulation: its thick 120 mils
thermal conductivity: 0.23 btu.in/hr.ft2 or 0.033 W/m.K
Tank has diptube and spiral ring at bottom. Ring has 6 distributing holes.
No reaction takes place inside tank.
I hope above information is enough to find re-circulation rate.
A new heat exchanger may select as per re-circulation rate and heat load. that will not be a big deal. Hot water is going to be heating media in heat exchanger.
Thanks,
Santosh