Sulphur Tank Foundation_HOT SERVICE

[Rahulvaland]

I am handling a Liquid sulphur storage tank (42 m Dia x 9 m Ht) whose operating temperature is 150 deg.C.

PWHT for process reason is not required for this tank.

This tank is provided with,
1) Heating coils on Tank Bottom, Shell & Roof.
2) Mineral wool insulation on Tank shell & roof.

I want to know whether any insulation (i.e. Mineral wool, Fire bricks, Refractory castables etc.) is required between Tank bottom & Foundation or not. If required, shall it be covered with all area in contact with bottom plate or it shall be restricted to Ring wall only.

Also kindly clarify that who will decide the bottom insulation requirement (i.e. Civil , Process or Equipment dept.)?

 

[dhengr]

300° F is pretty hot to the touch, if you are handling that tank very much. Otherwise, I would think that heat loss through the foundation would be a big issue since you are insulating and heating all other surfaces. Assuming a steel floor plate, the tank designer can provide either a ring found. with granular fill inside and under the tank floor; or he can provide a 44 m dia. slab type found. under the floor plate and tank wall hold down system. I would think you could find some sort of refractory foam blocks (think space shuttle tiles) to install btwn. the conc. found. slab (or soil) and a raised floor plate. That insulating material must be strong enough in compression to take the weight of the contents. Concrete is not a good insulator and some soils are not much better. With that kind of operating temp. someone will have to pay some special attention to tank expansion (circumference or dia. change) as relates to the hold down details and movement at that point.

 

[Rahulvaland]

Thanks dhengr .

with reference to your reply kindly note that, Our foundation type is concrete Ring wall (Ring width = 500 mm). And the inside slab is made up of compacted sand.

with above configuration, We were proposing the FIRE CLAY BRICKS on Ring wall surface inline with our PTR.

However, Tank vendor has proposed FOAM GLASS HLB on Ring wall surface & this material is also allowed as per hot Insulation specification

Can you suggest, which is the better from both above (FIRE CLAY BRICKS or FOAM GLASS HLB).

 

[MJCronin]

In my opinion, 42m is very large for a tank that will expand this much.

Will this be the largest diameter molten sulfur storage tank ever made ?

Where will this tank be installed ?

How will the large theremal expansion movements be considered in the piping design ? Will piping expansion loops be necessary ?

Will there be new and unique thermal expansion problems for this tank because of the extreme design ?

Out of basic respect for the participants in this forum, can you tell us of your final decision on the foundation design and,....perhaps.... submit a detail

Thank You...

 

[dhengr]

I’m not a storage tank designer by trade, but I don’t like the idea a loose fire bricks under my tank wall or hold down details, particularly as relates to the tank expansion and contraction. These will literally have to be some sort of a slip joint to accommodate the tank expansion and at the same time act as hold downs for any lateral loading. I suspect MJCronin knows storage tanks better than I do, so he can correct me if I’m too far out of line. I would raise the steel floor pl. high enough above the conc. found. ring to pass your foam glass blocks (whatever thickness above the sand) right out over the conc. ring and out to the steel shell, but not under it. I would use the glass foam blocks to insulate some distance down the inside surface of the conc. found. ring also. Then I would put the steel shell (say 1" up above the conc. found. ring) and the hold down detail or feet on slip plates/bearing plates directly on the conc. found. ring. Then you said you were going to insulate outside the shell with rock wool, and I would build some sort of insulating enclosure over each hold down detail, to drain and blend in with your rock wool, but allow movement. This tank probably needs a substantial stiffener ring or multi-ring structure as part of the entire bearing and hold down system to accommodate the expansion and force it to distribute fairly uniformly btwn. anchor points. You will likely get about a .75' change in shell circumference, or about .22' change in tank dia., that’s about 3" in dia. The anchor bolts and sliding bearing points must accommodate more than 1.5" of movement assuming equal distribution of the expansion movement.

I agree with MJCronin that’s a pretty big tank, and I’m not sure I like it from the structural standpoint, particularly as relates to this expansion and hold down detail standpoint. You might be better off with several smaller dia. and/or taller tanks for the same total volume. You might even save some heating energy over time, since one tank could be held at process temp. and the others at some lower storage or ready reserve temp.