Hypothetical near boiler piping idea

STEAM DOCTOR

Good morning. Trying to pick some of the steam brains. Let's say , for arguments sake, that I have boiler piped in 3". 3" header, 3" riser from the boiler.....But I am not confident that steam will be dry (exit velocity is higher then desired...). Is there any benefit or drawback to adding a 6"-3" coupling with a 6"-3" bushing, to create a steam separator, essentially a 2nd, external steam chest? The bushing will be on the top of the coupling to prevent water from pooling at the bottom of the coupling. Obviously more and bigger boiler risers and a bigger boiler header are ideal. But for argument's sake let's say that's not an option. This whole contraption will cost under $250. Any thoughts would be greatly appreciated.
 All of the numbers above are purely arbitrary.

SteamingatMohawk

What is your exit velocity based on? What is the number?
How many risers?

STEAM DOCTOR

The above scenario is made up. It's a figment of my imagination. Let's say for argument's sake that the exit velocity is 25 ft per second and circumstances prevent extra boiler risors or a larger header. Is there benefits to the above suggested addition. 

Jamie Hall

Not quite clear on what you are proposing here. Where is this 6x3 coupling going, and what does it attach to? If it's just the coupling and then immediately the bushing, and it's on a vertical line, there will be very little benefit if any -- any water droplets which come out with the reduction in velocity will fall back down to the bottom of the coupling and immediately be re-entrained. When enough water is trapped that way, it will carry out the top no reduction in total volume of water.

Steam drums or steam separators are wonderful, but they be big enough to really reduce the velocities and, perhaps more to the point, the geometry and connections have to be such that there is a real separation taking place between water droplets -- which fall, though slowly, and don't turn corners really well -- and the steam. This is one reason why a header a few feet long, one size larger than the risers (which need to be full size) works so well. Steam and water come whistling in one side near one end and the water tends to impinge on the opposite side , then drop in the slower flow and flow to the other end, where it drops to the equalizer (or other drain) while the outlets, near the top, really pick up only steam. while the water droplets just fly on by below. The greater the velocity difference the better, but there is such a thing as overkill.

STEAM DOCTOR

There is a company (in New England, I think) that makes/made an external steam separator. I am trying to make my own separator. 

ethicalpaul

I don't think the droplets would be retrained. If they hit the wall of the pipe they are very unlikely to get picked back up off of that. An oversized header does the same thing...it temporarily reduces velocity which will then increase again after the header.

ethicalpaul

I'd love to see a sketch of your proposed separator as it would be installed

STEAM DOCTOR

STEAM DOCTOR

Dan mentions such a device in Lost Art (that's where I got the idea). Steam anti surge tank. Was thinking to put it on vertical riser coming out of boiler. 

STEAM DOCTOR

Steamhead

By the time you've spent the time to engineer this and bought the materials, you've probably exceeded the cost of a new anti-surge tank..................

STEAM DOCTOR

@Steamhead. About $250 or so. One coupling and one bushing. Takes a few seconds to screw together 

STEAM DOCTOR

And you save a few pennies on the boiler riser. The 6" coupling ( or whatever size one might use), accounts for some vertical rise. 

ScottSecor

They used to push these steam separators at a local supplier made by Union Steam. http://www.unionsteam.com/

We prefer to keep it simple and follow standard piping practices.

Jamie Hall

A VERY important bit of the design of those steam separators may not be completely obvious: the outlet protrudes significantly INTO the separating chamber. This geometry will sharply reduce the degree of re-entrainment in the outflow. An additional modifcation -- though not really needed, perhaps -- would be to have the inlet arranged to enter so the flow is tangent to the side wall, and have a bottom relief for the separated water in the manner of a standard cyclone separator. But I think that's overkill. The protruding outlet pipe, though, is I think essential.

DanHolohan

The late Frank Gerety came up with a steam-drying idea that worked very well on bigger jobs, when he could get the client to listen to him. He called it a shotgun. He used a header that was oversized, with a second pipe on the inside of that horizontal header. That second pipe extended to within a foot of the end of the header before the header dropped into the equalizer. So, imagine a 6" header with a 3" internal pipe. The riser to the header ends in a tee, say 6 X 6 X 3 and a double-tap bushing. That three-inch opening is going to be the steam supply. The steam and the carryover water leave together, but when they get to the end of the 6" header, the steam makes a 180-turn, which the water can't do. The carryover water goes back into the boiler and very dry steam heads out to the building.

It worked exactly as promised, but most clients didn't want to go the extra expense. And not everyone believed Frank. I sure did.

STEAM DOCTOR

I am looking for a solution where there is either limited space or limited resources. Not instead of good piping. In addition to good piping. As always, my ears are open.

STEAM DOCTOR

I could always add a double tap bushing, to create my own drip leg. Apparently, the steam separators are still out there. I am reluctant to use them, because they only come come in 2". I can't say that I am comfortable enough, to reduce recommended pipe supply size. I am looking for an additional to proper piping, not a replacement. 

Jamie Hall

I'm a simple minded soul. So what I'd probably do is go to a 4 inch header and call it good...

STEAM DOCTOR

@Jamie Hall. Bigger header has been and will continue to be my go-to option. However, there are situations where every inch makes a difference. 4" T's are obviously bigger then 3" T's, for example. And a single separator can cost a good bit less then larger pipe fittings. Just trying to think a bit out of the box.  

EBEBRATT-Ed

I think a steam separator has limited value. If the boiler water is dirty you going to have operational (surging) problems with the boiler even if you do dry the steam to the building

STEAM DOCTOR

Back to the retrain issue. Do we really care if the the water retrains at the inlet, as long as the steam is dry at the outlet?

STEAM DOCTOR

@ethicalpaul. You probably have some extra time this summer. Maybe some experimenting?!? Separator without dip tube and with dip tube at different insert depths. Essentially, different lengths of nipples. 

ethicalpaul

haha I love the suggestion! But my boiler won't launch any water droplets even with a single 2" supply pipe.

I know you mentioned lack of space, but I think I'd rather see an undersized horizontal header than that vertical separator.

I take back what I said about droplets not being re-entrained...I think they would with this one...it reminds me too much of a percolator. I want to see the equalizer more in the path of the water's general direction as it gets carried by the steam.

EdTheHeaterMan

ethicalpaul said:

haha I love the suggestion! But my boiler won't launch any water droplets even with a single 2" supply pipe. .

Com'on Paul... You could repipe one of those risers to an 1-1/4 riser to induce the needed velocity. Then you can buy another 1-1/4 glass observation section. Since you are independently wealthy and nothing better to do.

Trying to shame Paul into getting you an answer @STEAM DOCTOR (hope it works) I love his videos!

STEAM DOCTOR

Took this off a boiler a few years ago. Some sort of external steam separator. 

delcrossv

STEAM DOCTOR said:

Took this off a boiler a few years ago. Some sort of external steam separator. 

You'd think you would want the steam inlet and outlet to be at opposite ends. (?)
Is there a baffle inside?

STEAM DOCTOR

Yes. There is/was a baffle. Steam would enter the left side, move right, water would drip back into return, steam would make a union above the baffel and exit out top left. 

mattmia2

Seems your limited space problem has already been solved with the drop header...

Tim_D

Frank Gerety was a smart guy. I did a motel out in the Hamptons in 1981 or 1982 where Frank designed a seasonal change over chilled water, hot water system piped primary secondary. I thought he was on drugs until he was kind enough to draw it out and explain it to me.

leonz

Assuming you have a boiler with two 3 inch steam tapping's a 3 inch double drop header feeding a 4 inch drop header to dry the steam would be so much simpler.

STEAM DOCTOR

Definitely not simpler. And definitely not easier. 4" fittings take up more space then 3" fittings. 2 4" fittings certainly take up more space then a single 3" fitting. All things being equal, I have and I will of course use 4" header and both 3" boiler tappings. My question is about the benefits of throwing in some 6". 

Jamie Hall

STEAM DOCTOR said:

Definitely not simpler. And definitely not easier. 4" fittings take up more space then 3" fittings. 2 4" fittings certainly take up more space then a single 3" fitting. All things being equal, I have and I will of course use 4" header and both 3" boiler tappings. My question is about the benefits of throwing in some 6". 

Simple question! Simple answer. Practically none...

gerry gill

DanHolohan said:

The late Frank Gerety came up with a steam-drying idea that worked very well on bigger jobs, when he could get the client to listen to him. He called it a shotgun. He used a header that was oversized, with a second pipe on the inside of that horizontal header. That second pipe extended to within a foot of the end of the header before the header dropped into the equalizer. So, imagine a 6" header with a 3" internal pipe. The riser to the header ends in a tee, say 6 X 6 X 3 and a double-tap bushing. That three-inch opening is going to be the steam supply. The steam and the carryover water leave together, but when they get to the end of the 6" header, the steam makes a 180-turn, which the water can't do. The carryover water goes back into the boiler and very dry steam heads out to the building.

It worked exactly as promised, but most clients didn't want to go the extra expense. And not everyone believed Frank. I sure did.

Dan....Dan....have you been holding back secrets on us. Were you planning on taking this info to the grave, lol... I love the technique...I'm gonna have to give this a shot..

gerry gill

Steam Doctor- yes it would help...I think it would help more if it was a tee with the steam entering sideways, and the water draining out the bottom and the steam exiting the top tho..There was a house around me that had the risers go up to a tank in the ceiling which had baffles in it. The pipes exited off one end of the tank. Worked great.

leonz

STEAM DOCTOR said:

Good morning. Trying to pick some of the steam brains. Let's say , for arguments sake, that I have boiler piped in 3". 3" header, 3" riser from the boiler.....But I am not confident that steam will be dry (exit velocity is higher then desired...). Is there any benefit or drawback to adding a 6"-3" coupling with a 6"-3" bushing, to create a steam separator, essentially a 2nd, external steam chest? The bushing will be on the top of the coupling to prevent water from pooling at the bottom of the coupling. Obviously more and bigger boiler risers and a bigger boiler header are ideal. But for argument's sake let's say that's not an option. This whole contraption will cost under $250. Any thoughts would be greatly appreciated.
 All of the numbers above are purely arbitrary.

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You do not need a great deal of ceiling height to take advantage of a double drop header with three inch to four inch transition unions to the four inch drop header and all its benefits making dry steam for you.

You should read the November 2020 post from patnh and the responses from the members about drop headers and low headroom situations.

There are plenty of pictures of drop headers here on the forum and on the web.

STEAM DOCTOR

Was thinking more for situation where there is limited horizontal space. Every one of my boilers is installed with drop header. 

jumper

Overhead two pipe distribution works so well partially because each terminal receives high quality steam. But nothing is free. Boiler works to lift droplets but does it recover work when droplets fall back into boiler?

leonz

I believe that using a single pipe top fed steam delivery method would be even simpler as explained in 500 PLAIN ANSWERS written by ALFRED GRANT KING on pages 50 and 51. In it he describes the John H. Mills overhead system of steam heating using overhead steam delivery.

"The main is taken up through the center of the building to the attic or top of the system and all risers and connections to the radiators are supplied by drop risers from above, all drips from risers and returns from radiators being connected into the main returns which are run in the basement."

"As all steam and water flow in the same direction there is little friction and the system is therefore considered very efficient and serviceable in any building to which it can be adapted"

dopey27177

Yes Frank Gerety was a genius. He did tons of consults in the N>Y area. Additionally he wrote a manual for the real estate industry that could be purchased from the N.Y. city book store.

Jake

jumper

leonz said:

I believe that using a single pipe top fed steam delivery method would be even simpler as explained in 500 PLAIN ANSWERS written by ALFRED GRANT KING on pages 50 and 51. In it he describes the John H. Mills overhead system of steam heating using overhead steam delivery.

"The main is taken up through the center of the building to the attic or top of the system and all risers and connections to the radiators are supplied by drop risers from above, all drips from risers and returns from radiators being connected into the main returns which are run in the basement."

"As all steam and water flow in the same direction there is little friction and the system is therefore considered very efficient and serviceable in any building to which it can be adapted"

Possibly easier & less expensive to install. Up to building designer to provided chase for vertical main and enough headroom for sloped horizontal mains.