The case of the lowered steam pressure, this Friday's case.

RayWohlfarth

While having lunch with the maintenance director for a small hospital, he asked if there was anything he could do to reduce his fuel costs. His physical plant had two old 150 HP steam boilers set at 100 psi. The laundry which worked from 7am to 3 pm required the 100 psi. After 3pm, the system only needed 50 psi. we replaced the burners with new burners a few years earlier. I suggested an oxygen trim system but he said he didn't have money for it. Our other suggestion, which he agreed to, was to install a second modulating control and operating pressure control set at 50 psi. Using a time clock, we had the boiler switch to the lower pressure controls when the laundry was closed. I followed up a month later and the customer said he did notice a drop in fuel usage but also noticed a spike in carryover. The OR staff noticed the sterilizers were plugging. Could this have anything to do with the lower steam pressure, he asked. What do you think? I will post the video Friday at 6am EST.

Sylvain

I read on another site:
"Two of the most common mechanical causes of carryover are operation in excess of design load and sudden increases in load."

So the question is:
is the spike in carryover happening when going back from 50 psi to 100 psi while opening the laundry?
(sudden increase in load)

The carryover might explain the plugging.
Then one solution could be to increase pressure more slowly.

EBEBRATT-Ed

There is some ASME rule about operating a high-pressure boiler at reduced pressure believe it or not I don't think it is allowed. Always sounded crazy to me but there is a reason for it.

bburd

The boiler steam outlets and piping were sized for 100 psig steam. 50 psig steam occupies a larger volume for the same load. The larger volume increased the velocity of the steam leaving the boiler, causing carryover of boiler water into the steam piping, aka wet steam. It also carried crud from the boiler up into the steam pipes, causing the plugging.

Sylvain

Lots of questions

EBEBRATT-Ed said:

There is some ASME rule about operating a high-pressure boiler at reduced pressure believe it or not I don't think it is allowed. Always sounded crazy to me but there is a reason for it.

But anyway, one has to start or stop the system from time to time. Are there special procedures given for this? pressure build-up speed?

bburd said:

The boiler steam outlets and piping were sized for 100 psig steam. 50 psig steam occupies a larger volume for the same load. The larger volume increased the velocity of the steam leaving the boiler,[...]

Would bringing the pressure back to 100 psi before opening the laundry solve the spike problem?
Was there a problem when opening/shuting the laundry when running at constant pressure? It seems not.
There is a load change anyway. How big and sudden?

retiredguy

I have to agree somewhat with @bburb that operating the boiler at a reduced steam pressure will enhance water carryover but only when the steam load causes the steam velocity to increase past it's design point. If this is the case, I do not know of any solutions that are not expensive. A steam separator, for example, would solve the problem but the installation is not inexpensive. Also I don't believe that reducing the steam pressure from 100PSI to 50PSI will save much money. I would look for other more cost effective means to increase the boiler or system's operating efficiency. Reducing the design operating pressure of a boiler always presented problems and usually were not worth the slight cost savings. Since I do not know this hospital or it's steam system I could only guess at a cure for your senario and most solutions would carry a hefty price tag.

RayWohlfarth

Thanks for all the expertise.
@Sylvain I heard that as well. It didnt have carryover when it ran at 100 psi.
@EBEBRATT-Ed Never heard that you cannot reduce the pressure but it makes sense. I know some fire tube boilers will ask you what the operating pressure is so they can properly size the steam outlet.
@bburd I believe its was because the velocity increased like you thought.
@retiredguy Yes sir each option is expensive. The least expensive was simply running the boiler at 100 psi
Steam system like messing with your head.
Have a great weekend!
I do not believe the carryover was caused by the increases from 50 to 100 psi because it was an hour before the laundry started. In addition, the old system didnt see elevated TDS when the laundry started.
I believe it was because the steam velocity increased from 63 feet per second at 100 psi to 114 feet per second at 50 psi. The TDS level dropped when the steam pressure remained at 100 psi. According to Spiral Sarco, steam velocities between 100 and 200 FPS is normal. Here is the link to the video.https://www.youtube.com/watch?v=58-gPMCuU4M

retiredguy

I am not trying to critique your job but do these boilers have turbulators in the fire tubes and draft controls to control draft? Are the water sides of the boiler clean and free of all scale? By the way, the picture shows I believe "Iron Fireman" burners. Are these the installed burners? Just curious.

RayWohlfarth

@retiredguy Now you're taxing my memory. LOL This was back when I had hair. They did have turbulators and a draft damper and control. They were Iron Fireman EED burners in there.

EBEBRATT-Ed

I installed 1 EED burner in my time. Thought it was a nice burner. I guess it never caught on because Iron Fireman went out of business. It was the last "new model" they came out with. Mid-late 1980s I think.

RayWohlfarth

@EBEBRATT-Ed I did like the iron fireman eed burner You could really fine tune the air to fuel ratio

Panheadsforever

I hated those iron fireman thank god they are gone but we had em and had to work with them . Good i guess for the small stuff.

RayWohlfarth

@Panheadsforever I did like the EED It's linkage allowed you to make find tuning on the air to fuel ratio much tighter.

EBEBRATT-Ed

Some Iron Fireman History,

In 1923 Thomas Harry Banfield and Cyrus Jury Parker took over an iron works in Portland, Oregon that was manufacturing a small coal stoker. The stoker didn’t work very well, so the men redesigned it and named it the Iron Fireman. It became a commercial success relatively quickly. Coal was an economical heat source, and the Iron Fireman filled a need for automatic control of residential coal fired systems. It could be fitted to an existing furnace or used as the workings of a new one. Parker became the president of the firm. In 1928 both men were involved in an air crash which claimed the life of Parker. Banfield recovered and succeeded him in company leadership.

By the time World War II broke out the firm had manufacturing facilities in Cleveland, Ohio and Toronto, Canada as well as the Portland facility. Their factories were pressed into war service making engines for Liberty ships, and they won the Maritime “M” award given to only about 3% of the manufacturers supporting the war’s maritime effort.

Following the war the company developed oil fired burners at their Cleveland facility, and consolidated the business to that location. The Whirlpower light commercial series (developed by Fred Runninger) and the A series atomizers (developed by Charlie Schrade) had their roots in that work. By 1960 Iron Fireman had a commanding presence in commercial power burner sales – reportedly about 60% of the US market. The coal stoker business was sold to the Will-Burt company. The oil burner business was bought by Space Comfort, a California firm, who relocated it to a new factory in Harrisonburg, Virginia, complete with palm trees in front of the building. The facility attracted the attention of the Garrett AiResearch division of Allied Signal, who was putting together an HVAC conglomerate to gain federal energy grants for the development of solar powered air conditioning. Garrett also purchased Dunham-Bush, a refrigeration and air conditioning firm, moved them into the factory with Iron Fireman and changed the focus of the business.

The 1980’s saw development of the EED burner (by Neil Rampley) and the Constant Flow fuel system (by Larry Gray) for meeting New York City’s stringent rules for firing rate limitation, where Iron Fireman had considerable sales success.

In 2000 Iron Fireman was acquired by Vapor Power, who moved operations to Franklin Park, Illinois, where they operated until production ceased in December 2011.

On Dec. 31st, 2011, the owners of Iron Fireman ceased burner production and sold all remaining assets of the Iron Fireman business to OEM Boiler Parts Inc., of Elizabethtown, PA- including all engineering and sales records, parts inventory and production tooling.

Neil Rampley who designed the EED burner formerly worked for Power Flame.

RayWohlfarth

@EBEBRATT-Ed That was impressive thanks I never knew that about Iron Fireman but still have one of their ashtrays LOL

jumper

EBEBRATT-Ed said:

There is some ASME rule about operating a high-pressure boiler at reduced pressure believe it or not I don't think it is allowed. Always sounded crazy to me but there is a reason for it.

I think there is a section in ASME code about derating a boiler.
I have seen rated boilers repurposed for heating and running at 0 psi.
Unless one really needs pressure or higher temperature; low pressure is preferable.

What makes client think his fuel consumption is too high?

RayWohlfarth

@jumper You're talking about accountants running the hospital Everything was too high

jumper

RayWohlfarth said:

@jumper You're talking about accountants running the hospital Everything was too high

We both know there's ways to reduce energy costs. But those ways are also too high.
Do you know why laundry requires 100 psi steam?

RayWohlfarth

@jumper no idea why they needed 100 psi I just remember him saying he needed it

bburd

High-pressure steam is needed for hospital and commercial laundries to provide high temperature heat for the dryers, irons and pressing machines (mangles). Saturated steam at 100 psig is 338°F.

EdTheHeaterMan

bburd said:

High-pressure steam is needed for hospital and commercial laundries to provide high temperature heat for the dryers, irons and pressing machines (mangles). Saturated steam at 100 psig is 338°F.

338°F. WOW! That ought to kill a germ or two!

RayWohlfarth

They were tough germs LOL

retiredguy

Remember this, with most of the newer sheet drier machines, you fed in a wet sheet and it was dried, and folded in one operation. So you needed the high steam pressure to complete that job correctly. Also, for the final rinse in the washer the rinse water is above 180F to kill all germs and sanitize the sheets just like in a commercial dish washer.

jumper

retiredguy said:

Remember this, with most of the newer sheet drier machines, you fed in a wet sheet and it was dried, and folded in one operation. So you needed the high steam pressure to complete that job correctly. Also, for the final rinse in the washer the rinse water is above 180F to kill all germs and sanitize the sheets just like in a commercial dish washer.

Is this legacy engineering? Designer copies a past project where 100 psi was available?
TorontoHydro supplied steam to downtown hospitals and I don't think it was 100 psi.

"Atmospheric boilers" can produce 250°. Inadequate for linen laundry? Even 50 psi is more than many autoclaves need.

RayWohlfarth

@jumper Im not sure People get told this is the way we do things and think its the law sometimes