Steam Generating Salt Cooler - ASME Section 1 ?

[Pavan Kumar]

Hi All,

I wanted to get an understanding if our Reactor Salt Cooler can be considered as Steam Boiler under ASME SEC 1. Our reactor temperature is maintained with molten salt whose temperature is regulated by a salt cooler. In the reactor the process gas is on the tube side while the molten salt is on the shell side. The molten salt picks up the exothermic heat of reaction and then passes through a valve into the Salt Cooler which brings back the molten Salt temperature to 400 Deg C the reaction temperature. In the salt cooler the molten is on the shell side while Boiler feed water is on the tube side. The BFW picks heat and becomes saturated steam at 265 psig. This steam is sent to the HP steam header. Now the question is should the Salt Cooler be treated as a Boiler under ASME Sec 1, as it is a steam generating equipment. I need to locate and size the PSV. Should this PSV be placed on the Salt Cooler or on the HP steam line from the salt cooler that connects to the HP steam Header. Can anyone share the PDF copy of ASME Sec 1 code even if it is an older version. The code of construction of the Salt Cooler is per ASME Sec VIII Div 1 per the Design document.

Thanks and Regards,

Pavan Kumar

 

[The Obturator]

Interesting though I myself can't provide a definitive answer. I looked at the proloue of current (2019 edition) of ASME I and it provides a list of steam generating plant which should be included or excluded. I've attached this as a .pdf which should give you the answer. I also think it is important to engage your certifying and/or insurance organisation so that they too agree and understand the final definition. Hope that helps.

Per ISO-4126, only the term Safety Valve is used regardless of application or design.

 

[MJCronin]

How about a hand-sketch of a preliminary PID ? ... How many lbsm/hr of steam do you expect to generate ???

What are the pressures in such a system ?... Where is the steam going to be used ?

What kind of water reservoir do you anticipate for your boiler ?... any deaerator or surge tank ?

The high corrosion rate of hot molten salt is legendary ... any ideas about the type of materials that you will be using AND their compatability with the approved materials listing in the ASME Boiler Code ?


Do you have a giant pile of money available to build this boiler ?....or does your client want this built out of carbon steel..... and, before you ask, YES alloys with a high percentage of Nickel ARE VERY EXPENSIVE

More information will give you better answers

MJCronin
Sr. Process Engineer

 

[vt2012]

If the Salt Cooler is constructed and stamped to ASME VIII Div. 1 then the relief device needs to be per ASME VIII. In my opinion it's as simple as that. HRSGs are frequently stamped to ASME VIII, even though they are steam generators.

Your other questions are more about the relief design and that should be studied and calculated by an experienced engineer. Ideally the relief device is installed directly on the pressure vessel to minimize inlet line loss.

 

[Pavan Kumar]

Hi MJCronin,

Attached with this message is the sketch for the above mentioned PSV. The steam generation capacity if 64000 lb/hr (Max). The Saturated Steam generated is at 265 psig. The steam is sent via the HP steam header to a Steam drum which also has a PSV at 306 psig. The BFW to the salt cooler comes from a Deaerator storage tank.

I donot know the material of construction of the tube side and shell side of this cooler, but I know that it is constructed as per ASME Sec VIII DIV 1.

Thanks and Regards,
Pavan Kumar

 

[Pavan Kumar]

Hi vt2012,

Yes the cooler is constructed per ASME SEC VIII DiV 1. I guess you are right the PSV should also sized per ASME Sec VIII. As far as I remember, unlike ASME Sec I there is no code limitation to place the PSV on the vessel nozzle without any inlet piping. I want to confirm what ASME Sec I says about location of the PSV.

Thanks and Regards,

Pavan Kumar

 

[IdanPV]

Pavan Kumar, as for your question regarding the location of the PSV:

I want to confirm what ASME Sec I says about location of the PSV.

Refer to ASME Section I

The pressure relief valve or valves shall be connected to the boiler independent of any other connection,
and attached as close as possible to the boiler or the normal steam flow path, without any unnecessary intervening pipe or fitting.

 

[MJCronin]

Pavan,

IMHO, You would be much better served if you move your questions to the "Boiler and Pressure Vessel" forum

Based on your PID, a couple of quick questions:

- How does the salt know how much to circulate to accomplish your steam generation goals ?

- Which type of salt do you want to use ?

- Do you rely only on the thermal difference between the "hot salt" and "cold salt" for circulation ? Why is there no circulation pump with a VFD ?

- Why did you choose a supremely corrosive and hard to handle media such as salt ? There are others available ....

- What happens with the salt when the whole system cools down ?

Regards

-MJC

MJCronin
Sr. Process Engineer