Steam and Hot Water Boilers made of Polymers

RomanGK_26986764589

Hello everybody

This may sound like a dumb question but can a steam or a hot water boiler be made of polymers (plastics) instead of cast iron?
My thinking is that there are polymers and plastic materials that can withstand the temperature of the boiling water just like an electric kettle made of plastic. So if the boiler is made of a polymer it won't rot out because of all the make up water like a cast iron boiler.
So can polymers be used in production of boilers instead of cast iron or is it unfeasible in terms of quality and longevity and too expensive?
Here's the link I found regarding the polymer use on boilers and pressure vessels: http://www.nationalboard.org/index.aspx?pageID=164&ID=246

kcopp

Interesting.... A few problems.
1. the plastic would act as an insulator from the flame.
2. the flame would burn/melt the plastic in minutes.
3. the plastic would fatigue at a fast rate.

Sailah

I'm actually researching plastics right now to utilize in a part we are manufacturing for a steam system component. I've had good luck with Teflon but it isn't strong. I tried epoxy laminates, died a quick death.

My most recent experiments have been with Ultem 1000 in bar stock. It can surely handle the heat I will expose it to say 250F. It is also much stronger and stiffer than PTFE.

But these exotic plastics are expensive per lb. A 1.5" bar a foot long is hundreds of dollars for some of the more exotics blends. The higher heat you go the more expensive it gets.

I tried the flame test using a propane torch 6" away from the ultem and it charred quickly.

ChrisJ

Problem is a gas and oil flame are both much higher than 250F.

What's a blue gas flame, 3000F? Though that obviously should never touch the block you're still going to see fairly high temperatures near the bottom of the block. I doubt even bakelite could handle it.

Ceramic would work, but just like plastic makes a fantastic insulator.

So as has been said, even if you could fine a plastic that will tolerate the heat, it'd still be too good of an insulator.

SWEI

The bottom of the HX assembly in current Triangle Tube boilers is made from polypropylene to handle condensate. Anything with flame impingement would have to be made out of metal or some kind of ceramic.

RomanGK_26986764589

Yes. Bottom part for example could be made out of metal in order to dissipate flame in order to not burn the plastic.

hot_rod

I've heard that exhaust manifolds for engines can be made with polymers.

I think you could blend a polymer for the heat, but maybe not so well for heat exchange. You can blend material into polymers, maybe some copper or stainless fibers like they do with concrete fiber mesh blends.

The outer case on many of the tube type Sermeta boilers are composite. I think HTP was the first to use the polymer case in a tube type mod con.


http://www.high-temperature-composites.com/doc/jec-magazine-nb53-dec-2009.pdf

Robert O'Brien

https://www.bnl.gov/newsroom/news.php?a=24484

Fred

You would think that a cast iron boiler could be coated, on all the interior surfaces with a polymer/composite or other non corrosive material.

hot_rod

Grundfos offers some pump models with a E-Coating to help protect the iron pump bodies. Most of their pumps are rated to 225F

Mark Eatherton

The Gianonni boilers have a non metallic (EP?) water jacket around a stainless steel burner containment assembly on their smallest units. Ceramic combustion chamber sounds interesting... I think we will start seeing more and more use of EP (Engineered Plastics) on low temp appliances, but would be very surprised if it made it to the steam boilers. Lot's of high grade long term stress going on there.

But if anyone 20 years ago would tell me we'd be able to buy boilers with plastic on them now, I'd probably had a good laugh... And here they are.

ME

jumper

Wondering the same as Fred. Frying pans' coatings withstand 450 ° so why not on wet side of boilers? Why not light wall tubes with internal coating for steam heating? Especially for condensate returns that seem to rot out regularly?

RomanGK_26986764589

I guess the price of the coating maybe prohibitive and will drive the price of boilers up. Lol, some frying pans can get expensive because of the above mentioned coating.

Fred

I would doubt the coatings would add significantly to the overall cost of the boiler but even so, If they increase the life of the boiler , significantly, it would make sense for the homeowner. Added life is probably a deterent for the boiler manufacturers though.

gliptitude

I've always wondered how those plastic electric kettles work, and if something similar could be implemented in a heating system.

.. Conventional wisdom says that gas is a much more efficient method of heating water, but the electric kettle that I had would produce boiling water amazingly fast, faster than a stove, two or three times faster than a microwave.

In a steam system designed for only periodic boiling, rather than constantly keeping water hot, it seems like a larger heavier duty version of the electric kettle in a redesigned form could be devised to produce steam for piped radiators - using electricity.

SWEI

It can be designed relatively easily. Only the smallest sizes could even run on a 200A electrical service, and you probably wouldn't like the bills.

ChrisJ

No wisdom ever said gas was a more efficient way to heat anything than electric.

Electric is 100%, or very near 100% efficient.

gliptitude

Then why are electric boilers so uncommon? .. Perhaps I used the word efficient in a confusing or inappropriate way. I guess I really meant cost efficient.

I had observed that through out this discussion it seemed to be an assumption that there was necessarily a super hot flame in the vicinity of the boiler vessel.

KC_Jones

ChrisJ said:

No wisdom ever said gas was a more efficient way to heat anything than electric.

Electric is 100%, or very near 100% efficient.

That's actually false. How efficient is the electric generation? Gas comes to your house and you burn it locally so the efficiency is pretty much what it is. Electric is manufactured so you have to look at what the efficiency of the fuel being burned to produce the electric is. Most people ignore this, you can't ignore it because you are paying for it. Why do most people pay so much more for electric than gas...generation costs. A typical coal fired steam turbine generator is roughly 40-45% efficient. The only electric production that is even close to the efficiency of a gas heating boiler in your house is hydro electric....what country has cheap electric and uses a ton of hydro?

I am curious about the plastic boiler concept. Remember to melt the plastic the water inside would have to be hot enough to melt the plastic. Man used to boil water in animal hides. The water cooled the vessel sufficiently that it could take the flames. I made a steam turbine generator when I was in high school. I soldered the legs on the side of the vessel. We heated the vessel with a map gas torch to produce the steam, everyone swore the legs would fall off. They did not, for that solder to melt the water would have had to get to the melting point. Not saying plastic boiler would work, just saying it is potentially more feasible than it presents on the surface.

ChrisJ

KC_Jones said:

ChrisJ said:

No wisdom ever said gas was a more efficient way to heat anything than electric.

Electric is 100%, or very near 100% efficient.

That's actually false. How efficient is the electric generation? Gas comes to your house and you burn it locally so the efficiency is pretty much what it is. Electric is manufactured so you have to look at what the efficiency of the fuel being burned to produce the electric is. Most people ignore this, you can't ignore it because you are paying for it. Why do most people pay so much more for electric than gas...generation costs. A typical coal fired steam turbine generator is roughly 40-45% efficient. The only electric production that is even close to the efficiency of a gas heating boiler in your house is hydro electric....what country has cheap electric and uses a ton of hydro?

I am curious about the plastic boiler concept. Remember to melt the plastic the water inside would have to be hot enough to melt the plastic. Man used to boil water in animal hides. The water cooled the vessel sufficiently that it could take the flames. I made a steam turbine generator when I was in high school. I soldered the legs on the side of the vessel. We heated the vessel with a map gas torch to produce the steam, everyone swore the legs would fall off. They did not, for that solder to melt the water would have had to get to the melting point. Not saying plastic boiler would work, just saying it is potentially more feasible than it presents on the surface.

I'm willing to bet electric generation is quite a bit more efficient than your heating boiler in real world figures. There's no way your (82.9% AFUE) boiler is actually 82.9% efficient even if it ran 100% of the time. What is the overall efficiency of the system on a mild day, 20%?

If you compared fuel input, let's say natural gas to be fair, generating electric, including transmission losses driving a heating element in your house to your gas boiler, I bet you'd throw up.

SWEI

Modern CCGT plants top out around 54%. ISTR reading something awhile back that most of the in-service plants are closer to 47%. Chop off another 6-30% in transmission losses (depending on how you measure those) and somewhere around 30-40% of the BTU's in the fuel end up as electrons at your meter.

AFUE numbers are imaginary, but thermal efficiency numbers make a relatively decent measure. Something like 65% - 90% for the range covering older, natural draft appliances to a properly sized, installed, and commissioned state-of-the art mod/con.

RomanGK_26986764589

As Fred mentioned, a boiler, made of plastic, can be produced but it may put the producers out of business since a plastic steam boiler won't rot out compared to a cast iron one. Maybe this is the reason we have plastic kettles but not plastic boilers because they simply won't be profitable?

Fred

Back in the early 2000's I worked for a company that tried to increase profitability of their technology by promoting a "Value Based Pricing" model. The price of the product was based on cost plus what they percieved the value of the product to be to the customer, based on a set of criteria and return to the customer over the IRS guidelines for the life of the product (Capital assets). What that meant was the price for the same product varied from customer to customer. Essentially they thought they could skim (no Pun intended) a portion of the customer's improved margins by increasing its operational effeciency. This was an option with conventional pricing also being available. Basically you paid the conventional pricing, initially and at the end of each year, all the throughput was tracked and the customer paid an annual fee based on a % of increased throughput/profitability. That model didn't fly, obviously because the rest of the industry didn't buy into that model (sell it, sell annual maintenance/support and walk away was always perceived to be the most profitable model). It did allow for a "scalable" pricing scheme that made it somewhat more appealing for the smaller customer but not for the larger customers where the money was to be made. I say all this to suggest that if a boiler manufacturer could come up with a top end product line and pricing model/scheme based on added boiler life (and truely stand behind the added life, no if's and's or buts) some modified version of this model could work, at least for a portion of the population. At a minimum, It might give that manufacturer a compeditive edge. Others who want lowest initial out of pocket cost could buy a model, as it is, using today's manufacturing processes and todays warranty experiences. Adding a non corrosive coating to the wet side of a conventional boiler would actually be the only additional step in the manufacturing process.
I'm sure the arrows will come soon!

jumper

If your electricity comes from hydroelectric,and you have a smart meter,and you use thermal storage then electric can be more efficient both energy wise and economically as well.

ChrisJ

SWEI said:

Modern CCGT plants top out around 54%. ISTR reading something awhile back that most of the in-service plants are closer to 47%. Chop off another 6-30% in transmission losses (depending on how you measure those) and somewhere around 30-40% of the BTU's in the fuel end up as electrons at your meter.

AFUE numbers are imaginary, but thermal efficiency numbers make a relatively decent measure. Something like 65% - 90% for the range covering older, natural draft appliances to a properly sized, installed, and commissioned state-of-the art mod/con.

AFUE numbers don't include system losses. I was speaking about the efficiency of a system as a whole, not just combustion efficiency.

Take a leaky old forced air system with limited returns that scores a 70% combustion efficiency and tell me what the overall system efficiency is. It's not going to even be close to 70%.

SWEI

My numbers were for rough thermal efficiency (of the appliance.) Changing to electricity might make that something like 95-98% but will not fix system inefficiencies (which as you pointed out can often be huge.)

ChrisJ

SWEI said:

My numbers were for rough thermal efficiency (of the appliance.) Changing to electricity might make that something like 95-98% but will not fix system inefficiencies (which as you pointed out can often be huge.)

I got sidetracked, sorry.
My mind was stuck on baseboard electric or those oil filled radiators like the ones I use from time to time.

Ever have it where your mind focuses on something and completely misses the entire conversation?

Canucker

https://plus.google.com/+BillCarter/posts/HQwnwHAQ4x6
I found this interesting. There's definitely interesting composites coming down the pipe

Jamie Hall

ChrisJ said:

No wisdom ever said gas was a more efficient way to heat anything than electric.

Electric is 100%, or very near 100% efficient.

Ah... well... in the home. Have you ever looked at the overall efficiency of a gas fired (or oil or coal?) powerplant? From fuel BTUs in to kilowatts out, only the very best approach 50%. Most run in the 40s.

If you are considering efficiency, please do the numbers right...

On the rapid heating kettles -- they do it by having the element fully immersed in the water.

And to the comment on 200 amp service... my boiler is fairly mid range. It would require about 100 KW. 500 amps at 220 volts. Somehow, I don't think so...

ChrisJ

Jamie Hall said:

ChrisJ said:

No wisdom ever said gas was a more efficient way to heat anything than electric.

Electric is 100%, or very near 100% efficient.

Ah... well... in the home. Have you ever looked at the overall efficiency of a gas fired (or oil or coal?) powerplant? From fuel BTUs in to kilowatts out, only the very best approach 50%. Most run in the 40s.

If you are considering efficiency, please do the numbers right...

On the rapid heating kettles -- they do it by having the element fully immersed in the water.

And to the comment on 200 amp service... my boiler is fairly mid range. It would require about 100 KW. 500 amps at 220 volts. Somehow, I don't think so...

Like I said previously,

"I got sidetracked, sorry.
My mind was stuck on baseboard electric or those oil filled radiators like the ones I use from time to time.

Ever have it where your mind focuses on something and completely misses the entire conversation? "

Jamie Hall

...

Ever have it where your mind focuses on something and completely misses the entire conversation? "


I don't even have to focus on something else to miss the entire conversation... one of the things that happens when you get older

nicholas bonham-carter

One of the problems with plastics is their large coefficient of expansion, when heated up.
I think any non metallic boilers will have to be ceramic, perhaps with metallic fibers to help with the heat conductivity.
The advantage would be light weight and more chemical stability in the presence of bad water.
At the very low pressures at which we should be running steam boilers, a very light, thin-walled section would make it easier to install a boiler in pieces. Ceramics also handle any thermal shocks better.--NBC

gliptitude

As far as profitability of a new boiler system of modern construction, and possibly much lower cost to consumer, I would think that this could be justified by selling many more of them to people who don't already have a boiler system at all. If it is simple and cost effective and can be branded as a functional solution, rather than a luxury solution, perhaps new installs of radiant systems could be made to increase.