Tall chimney liner 5

[corrosionman]

We are contemplating GRP for a loose liner in an industrial chimney 8 ft dia 270 ft high 60 degree Centigrade. Made up as 30 ft lengths, joined by flanges. Anyone know if there is any published data on such a project.How can we establish the buckling load for the lowest length .We guess it might be 0.5 inches thick from high quality laminate.Thanks in anticipation of any comments. David Whitlock.

 

[rnd2]

Consider a part panel compression test end to end at 65 deg. + temp over-rise safety margin.
Compare with the pro-rata weight of the complete structure + allowance for other forces that may induce sway, such as high wind.

 

[Compositepro]

It seems to me that if you already have a 270 ft tall chimney and you need to put a corrosion liner into it, it would be far more economical to either adhere the liner to the existing chimney or suspend the liner from the top. Your proposed approach appears to call for a new self-supporting structure inside the old one. This will require far more material than is needed for simply a "liner". Adhering the liner would make the existing chimney stronger and would be far less expensive.

 

[rd78]

David-

We are in the process of reviewing a series of large diameter GRP chimney liners. Never seen one joined by flanges, usually a field fiberglass joint. In terms of buckling and liner design in general, guidance can be obtained from ASTM D-5364. You need to establish the laminate make up before concluding anything about buckling capacity.

 

[corrosionman]

Friends, thanks for your greatly appreciated ideas. I run a GRP Company and enjoy Engineering design. My Client builds chimneys. Conventionally his crane erects a 12 mtr height of stainless steel internal liner then erects over it 12 mtrs of the external wind shield. The next liner is erected and flange bolted to the first liner, then the next wind shield, and so on. The recent high price of Stainless created his enquiry to my company for 7 GRP liners, flanged lengths of 8 feeet dia, 40 feet long. This leads to the idea of simply lining the wind shield with GRP, or with a resin type coating. I have experience with both these types of coatings and usually they detach from the steel due to thermal expansion differences. All ideas therefore very welcom .
rd78(structural) your own findings would be very very usefulland anything you might say will help formulate our plans. I am not a Chimney designer and find difficulty in comprehending an 85 mtr freestanding steel stack, even if the base is 3.6 mtr dia. The top sways 0.8 mtrs.. The flue gas can be contained by a good quality vinyl ester resin but the client wants 15 yrs life. The chimney builder believes his competitors are offering for a lined wind shield,and this gives me confidence to continue down this road.
Please keep your ideas coming , positive or negative.
Thanks in advance . David Whitlock.

 

[gvanbeek]

I assume with the low temperature stated(140°F), that there is a wet scrubber just prior to the stack. This is going to mean lots of wet hot air.

We are an end user, and have many stacks that are made of only FRP. Overall we have had good success with these. However, we have two stacks where the liner has completely delaminated from the structural layers. It started with blisters that reached as large as 2 feet by 4 feet.

The root cause investigation determined that the laminate was not properly cured prior to installation (using DSC of retained cut outs, and cutouts from the stack after service of 2 years) and that the liner was not properly prepped prior to application of the structural layers. The liner showed little if no signs of chemical attack after 4 years of service(ie High Barcols, no attack of the glass examined via SEM).

I would recommend eliminating the exotherms, especially between the corrosion and structural layers (applicable for hand layup throughout only). If you cannot eliminate the exotherm, then great care should be taken to prep the surface at each exotherm. Our company requires the surface to be ground after exotherms if more than 3 hours have elapsed or the surface is no longer tacky. I would also recommend post curing the resin as high of a temperature as you have the capacity, up to the Tg of the resin.

 

[Kiwikid]

An idea to throw around.

Why not go with a thin skin with an exoskeleton bonded to the outer surface. Scaffolding pipe for example at 500mm centres around the circumference. Scaf pipe has male female ends to guide and lock sections into place. U brackets aligned vertically on the steel outer skin to correspond with the scaf pipe skeleton.

Go for a flange joint and bond with epoxy resin. Caulk it to ensure a seal.

Simple to make, simple to install. Strong flexible and light.

 

[rd78]

David-

You are right to worry about the mismatch between the metallic and FRP thermal expansion. The idea of the all FRP chimney can work if you have the real estate to support it with a framework or guy wires. Wind oscillation can be a problem, moreso than with steel.

If you go with the internal liner, you support it at a convenient elevation, perhaps leaving the bottom half in tension and the upper section in compression. You'll need lateral supports periodically to ensure the liner doesn't become misaligned with respect the the chimney in a wind event.

Regards,
Rick D.