"typical" steam losses in a hospital

[BronYrAur]

I know every building is unique and rules of thumb can be a dangerous thing, but I am only trying to get an order of magnitude here. I have a large hospital with a high pressure steam boiler plant that is losing a lot of water. I don't have actual numbers back, but trends are being recorded. There are a lot of politics involved here, so the solution is not as simple as just going around and making sure condensate isn't being dumped to drain. I am in fact fairly certain that condensate is being dumped, so I am trying to put a quantity on it.

Given that we are in the summer now, I don't have any humidifier losses. As far as I know, sterilizer steam condensate comes back to the boiler plant, so I am thinking that my only significant loss should be from the deaerator vent and any flash tank and condensate receiver vents. All other condensate should come back to the plant. Am I missing anything?

With that in mind, is there a way to estimate the quantity of steam that I am losing through the vents in terms of a percentage of the overall plant capacity? I would guess no more than 2-3%, but I have nothing to back that up.

Any thoughts?

Thanks

 

[SAK9]

I can't help with you any real figures and they will be meaningless anyway.I would suggest you develop a flow diagram that contains all usage points that do not return steam ie kitchen,laundry,sterilisers,deaerator,blowdown etc.In the case of sterilisers only jacket heating steam can be recovered.Steam injected into the chamber can not be recovered as it is contaminated.

 

[ChasBean1]

Tough to say... if they keep up with trap maintenance, maybe the 2-3% you mention. If they don't, maybe 20-60%.

 

[chicopee]

Have you taken into account blown down losses?

 

[RossABQ]

I'm puzzled by your statement "Given that we are in the summer now, I don't have any humidifier losses." You aren't using boiler steam directly to humidify, are you?

 

[urgross]

Have you checked operator logs for make-up? I'd recommend also looking to see if in-house (at the boiler plant) steam is tracked as well, as I have seen that add up to 9-10% of total. Sterile process cart wash, lab, bed pan cleaners, food service, etc. can all add up to significant cumulative loss beyond normal leakage and trap loss.

Not sure why anyone would be surprised by direct steam injection for humidification as long as FDA amines are used. That is a very common practice. I don't recommend it as there is no control for airborne levels from OSHA and ACGIH, only for FDA ingestion levels.

If the boiler is old or does not have a good turndown ratio, at leat 8:1 for #2, I'd also recommend looking at peak load vs. summer load to see if a summer boiler is justified. In the middle of construction for an energy project based on summer boiler savings, so that could be the source. Is loss percentage comparable between summer and winter?

 

[RossABQ]

I can't imagine a hospital using direct steam injection, too many issues.

 

[urgross]

I can imagine it, as that os ASHRAE's current position. Control for FDA amine ingestion standards can be accurately controlled by pH. For airborne, no such controls exist, sampling would need to go to a NVLAP lab. What astounds me is seeing humidification to hospital pharmacy, PET, CT, respiratory, and other areas where you might expect to see respiratory impaired. The place I work for has installed chemical free steam generation for humidification and clean steam for pharmacy for exactly above reason. A lot of hospitals won't do this strictly based on cost/risk assessment. We are talking about well over a million dollars.

 

[RossABQ]

I should have said "direct utility steam injection", but I see we are on the same page, really. In a big hospital the general areas would be costly to use clean steam for humidification, and the risks may be low enough. Operating theaters, post-op, ICU... not so much.

 

[ChasBean1]

RossABQ, ganged humidification from a central source is common. Most are now NOT using morpholine (an odor resembling a combination of fish and ammonia).

Side anecdote, local hospital had much more condensate return than steam supplied. WTF, right? Turned out there were so many traps blowing by that they ran city water into condensate receivers to quench the steam/water mix so pumps wouldn’t cavitate and could return water to the plant…

Hmmm…

 

[BronYrAur]

Thanks everyone for your replies. I did not get email notifications of your postings and quite frankly forgot about this for the past few weeks. A big part of the problem here is the politics of the facility. The boiler operators (who I am associated with) do not know what happens to the steam once it leave the plant. I don't know humidifier types, etc. I don't know if the kitchen equipment uses steam or if any of that condensate is dumped. All I will know is how much steam is leaving the plant versus how much condensate is coming back. Still don't have the data, but that's all I will get along with the makeup water.

So, my purpose of asking the question was to try to gauge what the ideal losses of a plant should be through vents, blowdown, etc. In other words, if everything was running perfectly, how much make up water should I expect?

 

[ChasBean1]

Sound question and I don't have the data...

Just that routine trap maintenance and insulation upkeep is an easy payback.

 

[cry22]

expansion joints when used lose a lot a steam if you happen to have any.

I would like to add a word about the clean steam issue between Ross and Urgross:
I read a study long time ago by the US Army COE regarding this topic of amines.
The study found that even non FDA approved chemicals when metered provide TLV's below FDA max levels. The study found that systems using daily one-shot injection to be problematic, as the hour following the chemical injection results into 7 to 10 times the amine TLV levels, only to be normal towards the end of the day.

The key is to meter chemical injection based on alcalinity.

Someone wrote an article in ASHRAE about clean steam and scared the hell out of the industry.

 

[RossABQ]

Someone wrote an article in ASHRAE about clean steam and scared the hell out of the industry.

Someone at DriSteem???

 

[urgross]

Cry22,

What can FDA ingestion standards (which in all honesty should only be applicable to Nutrition & Food Service and Canteen) have to do with airborne inhalation standards? The levels given by ACGIH and OSHA for airborne cannot be controlled by pH, and I have seen no publication or knowledgeablke operater that has said different. ASHRAE published the 1998 design manual for hospitals and clinics which expresses this argument quite well. Certain sections of the hospital, such as pharmacy, should already be following that standard based on ISPE.

BronYaur,

A little more information is needed. Do you distribute at high pressure, then use PRV's to provide operable (60-psig, 30-psig) steam, then return all pressure gauges of condensate back to an atmospheric receiver? That would be common practice in comparison to directly piping all pressures back to DA tank for vent. If using common atmospheric tanks, you are probably losing about 10-12% flash steam at those locations.

 

[ChasBean1]

Odor thresholds cannot be discarded. I think you'll find that NO NIOSH or OSHA TLVs, STELs, or IDLHs are exceeded even with direct humidified steam treated with morpholine or other volatiles. But you'll sure hear about the odors from the occupants...