Tank Steam Heating Question 1

[jmk407]

I am working on a chemical plant relocation, specifically the utilities. The client can be described as a job-shop operation - their production is highly variable and depends on the customer's order. As such, storage tanks may be used to store various materials. I have a group of tanks that will store non-hazardous surfactants. The tanks have steam coils but in order to size the steam coils I need to know what temperature the material needs to be maintained at. Given the lack of information on the material, other than its type, I do not have specific melting points nor a "worst-case" melting point that the steam load can be calculated to maintained. The steam would be just to maintain the fluid above its melting point. How can the fluid temperature be figured scientifically?

Thank you

 

[Latexman]

We use about 100 surfactants in pour plants. The majority are liquid at 50 C. There are 1 or 2 where we need 80 C to keep them molten.

Scientifically? Get their surfactant list they have now, with melting points. Sure, things will change, but you have to have a basis, so this is just a snapshot in time. Then list them with melting points from low to high, and get agreement from the client where to draw the design line for tank storage. Some will be small volume, so you'll probably need a hot box or two and a drum add station or two.

Good luck,
Latexman

 

[MJCronin]

Does the steam system already exist ? Do you know the operating pressure of the system ?

If so, the "best you will be able to do" with regard to tank maintenance temperature is about 25F less than the saturated steam temperature.

For example, if the saturated steam system pressure is 150 psig, then the best you will be able to do for any tank on this system will be 366-25 = 341 F

 

[jmk407]

MJCronin,

They are relocating their facility and leaving their ancient Kewanee boilers behind. I am using this info to get an idea of the steam load to size the new boilers. Unfortunately their current operation is such that the boilers are on full fire 100% of the time, and all control is manual, so it's hard to get an idea of what they already do.

Thanks

 

[MJCronin]

Since you have so little information to base your design, I would consider specifying the "maximum reasonable" surface area for the steam system.

What size are the tanks ? Where are the suction nozzles ?

I suggest that you consider 1.5"NPS serpentine flat, horizontal piping configured about a foot above the tank bottom. Slope the pipe from the inlet to the outlet and place a steam trap and drip pot on the outlet.

See example at:

http://www.centralvalleytank.com/tank-accessories.html

 

[Latexman]

jmk407,

Very often I hear what you said about the "lack of information on the material". That is BS. Someone is just too lazy to dig for it. Are you located in a developed country? In most places on earth, the Material Safet Data Sheet (MSDS) has to legally be in your possession to sell, buy, store, or use a chemical. People who handle chemicals have to be trained on information (MSDS) about chemicals. An MSDS has some physical properties of it's chemical on it. I deal with chemials, including surfactants all the time. Their MSDS usually list a freezing point, melting point, pour point, gel point, or cloud point if the soap will phase change at or near ambient conditions. It's not there every time, but usually it is. Legally, these sources of data are at the plant you are moving, and they have to be in the new plant before these materials can be received. They probably have .pdfs of them they can e-mail to you.

There is also Product Data Sheets and other product literature available from the vendors. In this day of digital information, it's just waiting to be Googled.

So, whoever is responsible to supply the information on these surfactants to the project, I guarantee you, they have most of the information. It could be you don't know who has this information. It also could be this person doesn't know you need the information. But, it's there for the taking.



Good luck,
Latexman

 

[MJCronin]

Amen Latexman........Amen !

 

[25362]

Sometimes hot oils or even warm water or steam condensate are used when wishing to avoid scorching the material in the tanks.