Chimney lining system including frame-supported membrane

A chimney lining system is disclosed, in which a membrane, typically 60 mils thick, of corrosion-resistant alloy material is suspended within an external skeletal frame-work of less-expensive carbon steel. Hangers provide for radial expansion of the liner. However, inward movement of the hangers is restrained. Axially spaced circumferential corrugations located midway axially between where two membrane sections are stiffened, joined and connected to the framework, provide for axial expansion. The external framework is disposed within a tubular concrete chimney column. At several levels, grillages support the external framework from the wall of the chimney column. The structural grillages may bear upon load cells equipped to signal the build-up of sludge on the interior of the liner.

BACKGROUND OF THE INVENTION 
In the art of industrial chimney manufacture, the use of alloy materials to 
resist corrosion has become more acceptable in recent years, in spite of 
the relatively high costs associated with such materials. 
For the past several years, electric utilities and other industries in the 
U.S. have been required by law to reduce the amount of sulfur dioxide and 
other recognized pollutants emitted by their activities. One method to 
capture sulfur dioxide is the use of wet lime or limestone scurbbers. 
However, the use of these systems produces a wider range of chimney 
operating conditions ranging from low temperature, highly acidic, to 
alkaline at high temperatures. Alloy materials such as Alloy 625 and some 
stainless steels have been recognized as providing superior corrosion 
resistance to the broad spectrum of operation encountered downstream of 
FGD systems. However, the cost of alloy materials is prohibitive. 
The present inventor is a joint inventor named in the U.S. Pat. No. 
4,265,166, of Parker et al issued May 5, 1981, which patent relates to a 
chimney lining system which can utilize the superior corrosion resistance 
of alloy steels in scrubbed flue gas environment without using a heavy, 
very expensive alloy plate. The Parket et al system is particularly 
directed toward retrofit projects where the membrane would be installed 
within an existing steel lining. The system requires the use of flexible 
suspenders which permit radial expansion and uses horizontal corrugations 
for axial expansion. The resulting annulus between the membrane and the 
steel lining is subject to a partial vacuum pressure to enable the 
membrane to resist negative pressure and potential implosions within the 
chimney. Considered in the wider realm of industrial chimney manufacture, 
use and maintenance, the Parker et al system can be seen to possess 
certain disadvantages or shortcomings, including: 
(a) The horizontal corrugation providing axial expansion protrudes into the 
gas stream and, as a consequence, is subject to erosion. 
(b) The use of a partial vacuum pressure to resist negative pressure and 
implosions facilitates entry of contaminants into the annulus which will 
accelerate corrosion if cracks or holes occur. The vacuum pressure may 
also require additional stiffening on the exterior of the existing lining. 
(c) Once installed, the membrane cannot be serviced or inspected since it 
is hidden by the presence of the existing steel liner. 
(d) The system is not readily adaptable to new construction. 
SUMMARY OF THE INVENTION 
A chimney lining system is disclosed, in which a membrane, typically 60 
mils thick, of corrosion-resistant alloy material is suspended within an 
external skeletal frame-work of less-expensive carbon steel. Hangers 
provide for radial expansion of the liner. However inward movement of the 
hangers is restrained. Axially spaced circumferential corrugations located 
midway axially between where two membrane sections are stiffened, joined 
and connected to the framework, provide for axial expansion. The external 
framework is disposed within a tubular concrete chimney column. At several 
levels, grillages support the external framework from the wall of the 
chimney column. The structural grillages may bear upon load cells equipped 
to signal the build-up of sludge on the interior of the liner. 
The principles of the invention will be further discussed with reference to 
the drawings wherein a preferred embodiment is shown. The specifics 
illustrated in the drawings are intended to exemplify, rather than limit, 
aspects of the invention as defined in the claims.

DETAILED DESCRIPTION 
A typical modern industrial chimney column cast in place of concrete is 
shown at 10 in FIG. 1. Typically, from the top of the foundation at 12 to 
the top of the rainhood 14 (neglecting the height of the 
lightning-protection air terminals), the chimney measures eight hundred 
feet in height, is sixty-eight and two-thirds feet in outside diameter at 
the base. The concrete column tapers to twenty-seven feet in outside 
diameter at the top, with the rainhood being thirty and two-thirds feet in 
diameter. (The rainhood 14 is mounted to the liner as illustrated in FIG. 
8.) 
The typical chimney column 10 as shown is distingished by an access hatch 
16 next to the base, two diametrically opposed openings 18 for breeching 
20, e.g. beginning at the thirty-nine foot level, for twenty-three by 
eight foot breeching, and a plurality of symmetrically placed openings 22, 
24, 26 at the two hundred-thirty, five hundred-ten, and seven 
hundred-ninety foot levels for supporting support grillages 28, 30, 32. 
The openings 22, 24, 26 are shown closed on the outside by removable hatch 
covers 25. 
A tubular, largely open framework 34, typically fabricated of box-channel 
vertical legs 36, L-channels secured together back-to-back to form 
T-shaped horizontal and opposing spiral members 38, 40, 42 sandwiched 
about gusset plates 44 where oppositely spiraling struts 40, 42 cross a 
horizontal strut 38, and gusset plates 46 where horizontal struts cross 
vertical legs 36. As shown, at each level of the framework 34 above the 
breeching, gusset plates 44 and 46 alternate with one another around the 
circumference, with the series being staggered by one gusset plate from 
level to level. Typically, the distance between levels is twenty feet and 
there are eight vertical legs 36 spaced forty-five degrees apart around 
the circumference of the frame. Accordingly, each series of spiralling 
struts 40 and 42 takes eight levels to complete one turn about the 
circumference of the frame. Characteristically, the framework 34 is very 
open. A somewhat different arrangement 48 of struts and legs is indicated 
at the base of the frame and around the breeching, as illustrated in FIGS. 
2 and 3. Fixed supports for the breeching are provided at 50, sliding 
supports at 52, and perimetrically-extending respective stiffener plates 
at 54, 54, 56 and 56. 
The liner support frame 34 typically is fabricated of three-eights inch 
carbon steel plates, ASTM A36, bolted, riveted and/or welded together at 
the job site. 
The liner 58 is a tubular member fabricated, for the xost part, of thin 
(typically sixty-mil-thick) corrosion resistant alloy (e.g. ASTM B443) 
sheet formed as individual panels 60 each about six feet in finished 
height and circularly arcuate through one hundred-twenty degrees about a 
vertical axis, with a ten foot radius of curvature (not counting the 
external ribs 62). The three panels 60 at each level are fabricated 
together, e.g. by butt welding along vertical seams 64, which are 
staggered by sixty degrees, i.e. half a panel length, from level to level. 
Each panel, half-way up its height is shown provided with an externally 
concave/internally convex rolled rib 62 in the nature of a corrugation, to 
provide a circumferentially extending/vertically-active expansion joint 
for each level. Each rib 62 typically protrudes two inches, is one and 
one-half inches high, is concavely radiused at its bases and convexly 
radiused at its radially outer extent. 
At the lower end, the liner 58 is shown provided with a hollow cylindrical 
portion, e.g. thirty-one feet in height, made of the same alloy as the 
panels 60, but thicker, e.g. three-sixteenths or about a one-quarter of an 
inch thick. The lower end sub-assembly 66 includes transition 
intersections with the breeching 20, where the stiffeners 56 are provided, 
typically one-half inch by ten inch vertical plates, and at the bottom and 
top where stiffeners 54 are perimetrically provided, typically WT 6X26, 
both ASTM A36 carbon steel plate. The sub-assembly 66 includes a lower end 
wall 68 of the same corrosion-resistant alloy plate as the sidewall 
thereof. 
At the upper end, the liner 58 is shown provided with a cylindrical portion 
70, e.g. ten feet in height, made of the same alloy material as the lower 
end sub-assembly 66. The rainhood 14 is mounted to the cylindrical portion 
70 typically as shown in FIG. 8, to provide an upper end sub-assembly 72. 
The lower end sub-assembly and upper end sub-assembly typically are 
telescoped over the lower and upper ends of the main thin membrane portion 
of the liner 58 and circumferentially welded inside and out at the 
respective seams 74. 
The upper and lower edges of the panels 60 in each level of the liner are 
butt welded to the corresponding edges of the panels in the next upper and 
next lower levels at seams 76. Circumferentially extending L-brackets 78 
also are welded externally to the liner 58 with a respective radially 
inner flange 80 of each bracket covering a respective seam 76. The 
brackets 78 act as stiffening hoops for the membranous liner 58 and also 
to provide anchor points for connecting the liner to the framework 34 so 
as to support the liner 58 from the framework 34. 
Typically, at each place where the horizontal, radially extending outer 
flange 82 of a bracket 78 is radially and axially in line with the inner 
face of a square-sectioned tubular leg 36 of the liner support frame 34, a 
square-sectioned, radially extending arm 84 is provided so as to have its 
radially outer end welded to the inner face of the leg at 86 and its 
radially inner end provided with a flange having a radially elongated 
vertical slot provided therethrough at 88. Each such slot is typically 
nine-sixteenths inch wide by one and seven-eighths inch long. A 
corresponding round hole is formed vertically through the bracket 78 
horizontal flange 82, a pad of stiffly resilient, somewhat lubricous 
bearing material such as a Teflon polytetrafluorethylene pad with a round 
hole through it is sandwiched between the inner end flange of the arm 84 
and the flange 82 and a nut and bolt assembly 90 is secured through the 
aligned slot and hole, to finger-tightness, and a cotter pin is installed 
through the bolt shank to prevent loosening and loss of the nut. 
The rainhood 14 and circumferential brackets 78 may be made of the same 
alloy as the liner 58, e.g. ASTM B443. 
Although the weight of the liner 58 must be transferred to the support 
frame 34 at frequent intervals because the liner is so relatively 
insubstantial in structural strength, the liner support frame needs far 
less numerous individual support points. The weight of the lowest section 
of the support frame 34, i.e. all below the grillage 28 is carried on the 
foundation at the base of the frame 34, with part of the weight of the 
breeching being carried at 52. The weight of the support framework also is 
carried to the concrete shaft 10 at the levels of the grillages 28, 30 and 
32. The base arrangement 48 of the framework is also secured to the cement 
shaft 10 just below the breeching, at 92. 
At each of the grillage levels shown in FIGS. 11, 12 and 13 there are two 
horizontal, parallel I-beams 94, 96, 98 respectively tangent to the liner 
support frame 34 at diametrically opposed sides, so as to intersect four 
respective legs of the liner support frame. The opposite ends of the beams 
94, 96, 98 rest on piers 100 mounted on the ledges 102 in the respective 
openings 22, 24, 26. At the level of the grillages 28, 30, and 32, a 
second pair of parallel beams 104, 106, 108 crosses the first at right 
angles and is tangent to another opposed pair of sides, so as to intersect 
the other four respective legs of the liner support frame. A similar set 
of two pairs of crossed interconnected beams 110, 112 is provided at the 
sub-breeching level shown in FIG. 10. 
At the level shown in FIG. 10 both pairs of beams 110, 112 are anchored at 
the ends to the wall of the shaft 10 from the inside, e.g. using anchor 
bolts 114 at outer ends of ties 116 constituted by paired L-brackets 
welded together as T's having their inner ends appropriately welded to the 
respective beam or to the frame 34 near its intersection with the 
respective beam. Similar ties are provided at the levels shown at 116 in 
FIGS. 11, 12 and 13. The details of a representative tie 116 are shown in 
FIG. 14. 
At the upper most grillage level shown in FIG. 13, the two pairs of I-beams 
98, 108 are arranged in a square, so that the comparable ends of two 
I-beams which extend at right angles to one another rest on the same pier 
100 on the same ledge 102. 
The beam-on-pier connections typified by the one illustrated in FIG. 15 
primarily bear a portion of the weight of the liner support frame 34 and 
liner 58 associated therewith. The tie-to-anchor connections typified by 
the one illustrated in FIG. 14 are primarily for maintaining the 
frame/liner assembly centralized in the chimney column. The two types of 
connections are preferably evenly distributed, alternating with one 
another, i.e. having their series intercalated at the various levels, as 
illustrated in FIGS. 10, 11, 12 and 13. 
The piers 100 preferably incorporate load cells 104, as indicated, in order 
that the potential increase in weight at any grillage level can be 
monitored. An increase in weight can be interpreted to indicate that 
sludge or other waste is building up on the inside of such portion of the 
liner as is supported from that grillage. These load cells 104, the 
instrumentation thereof and the manner in which they are coupled to the 
respective grillages is otherwise conventional. 
Sometimes herein the liner 58 is referred to as a "membrane"; this is not 
to imply that its wall is intentionally pervious, or semipervious to any 
solid, liquid or gas in either direction, for it is intended to be 
gas-tight. The sole implication of "membrane" as used, is that the liner, 
at typically 60 mils thick, is very thin in comparison with what would be 
necessary for a free-standing, implosion-proof liner. 
What the invention provides for an industrial chimney, e.g. a tall tubular, 
conical column of concrete, is tubular liner membrane of 
corrosion-resistant, expensive material such as a high nickel alloy that 
is supported axially and against radial collapse by an external open 
framework made of a strong, less expensive (usually less corrosion 
resistant) material, such as carbon steel plate generally fabricated by 
welding. The structural frame is, in turn, suspended at the base on the 
chimney foundation, and from grillages which are supported from the 
chimney column. The membrane is supported from the frame at regular 
intervals. The spacing of the intervals is determined by evaluating the 
effect the temperature and pressure of the gas being vented has on the 
liner material. Axial expansion is accommodated by the formed horizontal 
corrugations in the liner; these corrugations are formed midway between 
support levels. Radial expansion of the liner relative to the liner 
support frame is accommodated by slots and lubricous bearing pads where 
the liner is supported from the liner support frame. Resistance to local 
circumferential buckling of the liner is provided by the corrugations, and 
by ring-shaped stiffeners secured to the liner over the circumferential 
butt joints between levels of panels of the liner. Additional resistance 
is provided by the liner support frame, due to its multiplicity of 
well-distributed connections to the membrane at the support points. 
Because the ring-shaped stiffeners are provided at the horizontal joints, 
during field butt welding of the panels at these joints, the ring-shaped 
stiffeners function as back-up bars. 
Especially where the chimney liner system will be subjected to higher 
elevated temperatures, an additional expansion joint should be provided 
for the liner 58 directly above the level of each grillage. A 
specially-designed expansion joint for this purpose is typically 
illustrated at 120 in FIG. 16. 
There is shown in FIGS. 17 and 18, a hanger 122 for connecting the liner 58 
to the structural frame 34. Hangers 122 can be used in place of respective 
ones of any or all of the connectors 78-90, which have been described 
hereinbefore in relation to FIGS. 6 and 7. 
In FIGS. 17 and 18, the seam 76 where the upper edge of a lower panel 60 is 
welded to the lower edge of an upper panel is externally covered by the 
inner flange 80' of a welded-in-place, circumferentially extending 
stiffener 78' having a modified I-shaped transverse cross-sectional 
figure. 
At each hanger 122, two vertically, axially short brackets 84', 84" are 
mounted, e.g. by welding, to the inner face of the respective leg 36 of 
the structural support 34. Each bracket 84', 84" extends horizontally, 
radially towards the liner 58, but terminates short of the liner 58 so as 
to leave gaps 124 between the brackets 84', 84" and the liner 58. The 
brackets 84', 84" are vertically spaced a short distance from one another 
but superimposed so that the slots 126 are in vertical registration. Each 
slot 126 thus is elongated radially inwardly toward the liner 58 from the 
leg 36 on which it is mounted. 
A similar vertically, axially short bracket 128 is mounted on the radially 
outer flange 131 of the stiffener 78, e.g. by welding, so as to extend 
horizontally, radially towards the leg 36. The vertical slot 130 through 
the bracket 128 is in vertical registry with the slots 126 and is 
elongated radially outwardly toward the leg 36. The bracket 128 is shorter 
in the radial direction than are the brackets 84', 84", leaving a larger 
gap at 132 than the gaps 124. A hanger 134 in the form of a short section 
of box channel is inserted through all three aligned slots 126, 126 and 
130, and is laterally, horizontally pivotally pinned near its upper and 
lower ends respectively to the upper bracket 84' and the bracket 128, e.g. 
by respective nut and bolt assemblies 136. Preferably the disposition of 
the brackets, slots and pivots relative to one another, as shown, are such 
as to prevent substantial inward movement of the liner 58 from the 
structural support 34 from the datum location shown, to prevent 
substantial angular rotational movement of the liner 58 relative to the 
support 34, but permit a greater degree of radial expansion of the liner 
58 towards the structural support 34 from the datum location shown (and 
respective contraction back to the datum location). 
The form of hanging means shown in FIGS. 17 and 18 currently is preferred 
over the form of hanging means shown in FIGS. 6 and 7, the one shown in 
FIGS. 17 and 18 presently being believed to be easier to install, by field 
welding and bolting, and because it provides a more positive means for 
permitting radial expansion, offers a greater resistance to implosion and 
earthquake shear, and is considered to be more reliable in operation. 
Because the chimney column 10 may be basically conventional but for the 
accommodations shown for supporting the structural framework 34, the 
subcombination of the liner with the structural framework may itself be 
considered to be an improvement. 
When a chimney column is provided with a frame-supported 
corrosion-resistant liner in accordance with the principles of the present 
invention, the chimney is given superior resistance to corrosion. The same 
basic design can be used in a variety of situations where there are wide 
variations in operating temperatures. The liner is light in weight, yet 
the liner/frame assembly has an excellent structural capacity. No 
pressurization system is needed for the annulus between the chimney column 
and the liner, nor between the chimney column and the frame, nor between 
the frame and the liner. Indeed, the frame is largely open work so that 
the liner may be inspected and maintained without requiring a plant 
shut-down. 
It should now be apparent that the chimney lining system including 
frame-supported membrane as described hereinabove, possesses each of the 
attributes set forth in the specification under the heading "Summary of 
the Invention" hereinbefore. Because it can be modified to some extent 
without departing from the principles thereof as they have been outlined 
and explained in this specification, the present invention should be 
understood as encompassing all such modifications as are within the spirit 
and scope of the following claims.