Boiler Code Requirements for Unfired Steam Boiler and ORC

[BradF]

I am designing a small scale Waste Heat Recovery power system (Rankine cycle) for various applications of generating electricity from waste heat. We will use a Waste Heat Recovery Unit (Heat Exchanger) as our "boiler" - note that it will NOT be a fired unit. We can run either on steam or on a refrigerant (Organic Rankine Cycle) and I am looking for some more information on typical requirements for system supervision.

I have been told that Organic Rankine Cycle (ORC) systems are exempt from the requirement of having a licensed boiler operator supervising the system, as required for using steam as a working fluid, where supposedly you need a full time supervision by a licensed operator for any steam above 15 psig. This seems like kind of a loophole if it is true, considering high pressure/high temp vapor (around 180 psig, up to 500 F) would seem to be equally dangerous if it were a refrigerant or water. Both systems are closed-loop, completely self contained.

Our applications are small (usually less than 500 kW thermal energy), and licensing requirements will be a obviously very important factor for Operations & Maintenance, if indeed they do not apply to ORC systems. I realize the regulations are likely to vary by State and by Country, but are there any consistent guidelines? I think the ASME International Boiler and Pressure Vessel Code is probably the relevant guideline, but what I've found so far has been vague between water/refrigerant. Can you get away with not having constant supervision of an unfired steam boiler (just heat exchangers, pump, turbine, piping) at any power level if you are pressurizing to 180 psig? Does superheating impose additional limits? Do the US, Europe, Asia operate under the same general rules?

Thanks for any help or direction you can give.

Brad

 

[metengr]

ASME Boiler and Pressure Vessel Code is a construction code not an in-service or operational code for users.

You must check with your local Jurisdiction where the object is installed, period. Why? Because most Jurisdictions have very specific rules for boiler supervision developed by the Chief or their Boiler Boards.

 

[BradF]

Understood and agreed on the local specific rules, and for any given installation this will obviously be done. My question is more general - I suppose I should clarify that I am looking for some sort of "common thread" among regulations in general. Specifically:

- Are local regulations so inconsistent that it could indeed be possible to make 200 psi steam with no boiler operator in Utah but not in New York?
- Do refrigerant evaporators in a high temp/high pressure ORC as described above really avoid the regulations that fall on steam?
- Is it possible to have a small scale, steam power plant that does not require constant, licensed supervision anywhere? I know that these exist for ORC applications in the US and abroad.

Thanks

 

[metengr]

BradF;
I can tell you from my exposure with the National Board and Chiefs that there are common threads regarding boiler supervision to promote safety. The inconsistency is boiler size and application.

Jurisdictions in the US are all unique, and as I mentioned some have very specific rules and exemptions.

 

[steve99f]

Within the US not only do you have state law to deal with but also municipal regulation as well. In PA, as an example, there is no state wide requirement to license boiler operators. The City of Philadelphia does though. In New Jersey they have very specific rules for licensing.

The National Board website has links to the various jurisdictional rules for member jurisdicitons in their synopsis. Remember though, not all jurisdicitons are members.

 

[GenB]

jurisd conserns are merely safety; steam and hot water are of explosive nature,
in CA there are companies who get away with >15psi and >miniature systems by not reporting.