GB2099972A - A chimney having smoke conduits consisting of suspended sections connected by joints - Google Patents

Abstract

A chimney for industrial exhausts comprises an outer building structure, inner vertically spaced apart platforms, and inner smoke conduits; the smoke conduits are made of insulated metal sections, each of which is isostatically suspended to a platform (14) by tie rods or suspension devices: a guide system ensures the congruence of adjoining ends of two conduit sections; and expansion and insulation joint between adjoining sections (18) comprises flexible annular inner and outer bands (48, 49), which are impervious to smoke and reinforced; a space between the bands is filled up with insulating material (50). <IMAGE>

Description

SPECIFICATION A chimney having smoke conduits consisting of suspended sections connected by joints This patent application relates to smoke conduits for industrial chimneys.

In the last few years industrial chimneys have been madewhich have an outer building structure, for example a reinforced concrete structure, and one or more inner metal conduits for smoke conveyance.

The outer building structure serves the purpose of withstanding stresses due to permanent loads, wind action, and possible seismic movements and thermal stresses due to insolation; the inner conduits serve the only purpose of smoke conveyance.

Chimneys have been made in which each inner conduit comprises a single continuous barrel.

However, recently the trend was towards chimneys in which each inner conduit lengthwise consists of a plurality of sections, in order to obviate to the many disadvantage of single section conduit chimneys, such as complications in building, undue costs, considerable thermal expansions.

In known chimneys, with conduits made of a plurality of sections, each section is generally supported on a platform, and a plurality of such platforms are spaced apart within the building structure.

In some chimneys each of the sections expands upward from the platform, in other chimneys it expands downward from the platform, and various arrangements have been designed for providing a connection or linkage between the various sections.

A basic requirement for such connections is that they are impervious to smoke and yet they do not transmit any stress between one section and the other. The connections should also be sufficiently durable and easy to survey.

An earlier patent granted to the same applicant, Italian patent N. 1.042.501 corresponding to GB patent 1.584.399 discloses a chimney wherein the inner conduits are made in form of a plurality of sections each of them being suspended to a platform extrados within the building structure, and a connecting joint between adjoining sections comprises a textile flexible band outside the sections, an annular basin integral with a lower section, and filled with sand and boiled oil; and a blade integral with a lower end of an upper section, said blade plunging with its lower edge into said basin.

Although the chimney according to the earlier patent N.1.584.399 has achieved excellent results, however in the elapse of the years it also shows some drawbacks; namely, it is questionable whether the joint sealing material (sand and oil) will keep its characteristic constant in time; it is difficult to provide a substantially automatic topping up system for the oil in case of evaporation or degradation of same; it is also necessary to provide for a local washing to remove carbonaceous deposits due to smoke, deposits which in time could cause the jamming of the coupling joint between adjoining sections.

Further requirements in the field are determined by the standards of E.N.E.L. (an Italian National Organization for Electric Energy) requiring, for chimneys of power plants, that each conduit section must be isostatically suspended, and that the system assuring the congruence between the sections must be such as not to generate restraints on the sections such as to vary the isostatic condition.

The chimney according to the present invention has been provided, in order to meet the hitherto outlined requirements. This chimney substantially comprises; an outer supporting structure; inner platforms spaced apart along said structure; smoke conveyance conduits or ducts internally of the structure, each of said conduits consisting of conduit sections; each conduit section being supported by a platform and connected to at least one adjoining section of the conduit through a connecting joint.

The chimney is characterized in that said connecting joint comprises an inner flexible band connected between adjacent ends of said two sections, an outer flexible band connected near the adjacent ends of said two sections, and a filling of insulating material between said two bands. Preferably, said two bands are formed of a plurality of layers and generally comprise layers of fabric of Teflon (trademark for polytetrafluroethylene) and glass and/or asbestos fiber and nets of stainless steel, while said filling preferably comprises loose mineral wool. According to a further feature, said joint also comprises an inner circumferential projection integral with the inner wall of the lower conduit section and a tapered portion integral with the lower end of the upper conduit section (in order to assure the best flow dynamics solution in such a zone).

According to a further feature, a guide system between the sections is incorporated within each of the joints, said system consisting of a plurality of guide devices, each of which includes a rod integral with a section and rollers or pads spring pressed on the sides of said rod and integral with the other section.

According to a still further feature, each conduit section is supported by the respective platform through suspension devices secured to the platform intrados and to the said section; said devices are circumferentially spaced apart around the section, and each device comprises a cylinder, a stem sliding in the cylinder and a spring interposed between the cylinder and the stem.

The new chimney meets the requirements set forth by the standards of E.N.E.L. as to industrial chimneys for power plants, that is to say, each section is isostatically suspended under any load condition; each section is free to expands without involving the other sections, while the adjoining ends of the sections are maintained congruent.

Additionally, the joint for the new chimney has the advantage of rapid execution and lower manufacturing cost compared with the joints of the prior art.

Still further a long duration is foreseen for the new joint with substantially unaltered elastic properties and it is expected that the said joint will not be substantially affected by carbonaceous deposits due to smoke. The joint can further be surveyed by gauges overseeable from the platforms, or possibly connected with a continuous supervision system in a control room of the plant.

The invention will now be described in further detail with reference to the accompanying drawings, showing by only way of unrestrictive example an embodiment thereof, and in which: Figure 1 is a diagrammatic axial sectional view taken along a chimney having a plurality of barrels or conduits according to the invention; Figure 2 is an enlarged fragmentary crosssectional view substantially taken along plane 2-2 of Figure 1; Figure 3 is an enlarged fragmentary crosssectional view substantially taken along plane 3-3 of Figure 1; Figure 4 is a fragmentary axial sectional view, on an enlarged scale relative to Figures 1, 2 and 3, taken at a joint between two adjoining sections of a smoke conveyance conduit;; Figure 5 is an axial sectional view similar to Figure 4, but on further enlarged scale, taken along an axial plane through one of the guide devices which ensures the congruency of adjoining ends of two successive barrel sections; the device is shown partially in section and the outline of the joint is shown by dash lines; Figure 6 is a fragmentary view, from the left of Figure 5, the joint material having been removed to show the underlying parts; Figure 7is an axial sectional view, on an enlarged scale relative to Figure 1, taken on a plane passing through a suspension device, holding a barrel section from a platform; the device is shown in section; and Figure 8 is a fragmentary sectional view according to line 8-8 of Figure 7.

A chimney 10 according to the invention comprises a building structure, generally of reinforced concrete, designated as a whole at 12, and, internally thereto, plartforms 14 which are spaced apart from one another; such platforms may be of any desired type, and generally comprise metal frames supported on brackets 13 of the building structure.

Smoke conduits or ducts, each of which is generally indicated by the reference numeral 16, may be in any desired number; only two of them are shown in Figure 1 in order not to complicate the illustration unduly; two conduits are also shown in each fragmentary Figure 2 and 3, in which the chimney thus comprises four conduits. Each conduit 16 includes a plurality of consecutive sections 18 and each section 18 is supported and suspended to a platform 14 through suspension devices 20, which will be further described in the following. Each section is joined or connected at each end to an adjoining section by a joint 22, to be described in the following, and the congruency of the ends of adjacent sections is maintained by guide devices 24, to be described in the following.

In the first place the suspension system is described with particular reference to Figures 1,3,7 and 8. Each barrel section 18 is suspended by suspension devices 20 to the intrados or lower face of a relative platform 14. The number of the devices 20 is calculated according to the static and dynamic weight of the barrel section; particularly, in Figure 3, there are eight devices 20. The arrangement of each suspended section with respect to the relative platform is preferably such that the upper end of the section is at about a man's height over the platform.

Each suspension device 20 is connected to the platform 14 by a length of a metal structural shape or section 26. The latter has an upper flange 29 of a cylinder member 30 bolted thereto, by bolts of which onlythe axes 28 are shown in Figure 7, the cylinder member 30, having a lower wall 32 secured to a lower flange 33. A stem 34 cooperates with said cylinder member 30 and carries an enlarged cap 35 at the upper end; between said cap and wall 32 a pressing spring 36 is interposed. The stem 34 is accomodated within an opening 38 of a bracket 39 secured to angle bars 40 integral with the conduit section 18. The threaded end 34' of the stem projects from the hole or opening 38 and engages a supporting element 41, being clamped thereto by a nut 42.

An insulation 43,43' is placed between the supporting element 41 and bracket 39 and between the stem 34 and hole 38; (the insulation indicated at 43 generally comprises a plurality of layers of treated asbestos, and the insulation indicated at 43' generally comprises loose mineral wool) so as to avoid a thermal bridge (i.e. a portion having a higher heat conductivity than the adjacent portions) at the contact area between the suspension device and the bracket 39. In Figure 7 and in other Figures of the accompanying drawings, reference numeral 19 designates a layer of insulation placed about each conduit or barrel 16.

With a suspension arrangement utilizing the devices 20 above described, each of the conduit sections is suspended to the relative platform through the springs 36; this ensures a suspension always under isostatic conditions and the possibility of maintaining the barrel at vertical position, which condition would fail in case of rigid suspension.

Thus, the deformation of the outer structure due to mechanical agents, such as wind, earthquake, insolation, etc., involves rotations and displacements of the platforms 14. Therefore, in case of rigid connection, a rotation of the barrel would occur, which is instead avoided by said suspension arrangement.

With reference to Figure 4, a joint between two adjoining sections 18 will now be described.

As shown in the fragmentary sectional view of Figure 4, each upper conduit section 18 has a tapered lower edge 45 secured at 45' to the remainder of section 18 in any known manner; the edge 45 terminates within the upper end of the underlying conduit section 18. Each section 18 is suitably insulated by a layer of insulating material 19, as above referred to.

The joint 22 comprises a first inner annular band 48, a second safety outer annular band 49 and an insulating filling 50. The inner annular band 48 comprises a plurality of layers of impervious materials for withstanding the chemical, physical and thermal stresses, such as, for example, Teflon-glass fabrics reinforced with nets of stainless steel, and is secured between an angle bar 48a integral with the upper section and an angle bar 48b integral with the lower section.

The outer annular band 49 generally consists of a plurality of layers comprising a fabric made of Teflon and fiber glass and/or asbestos fiber, and a plurality of nets of stainlees steel; said band 49 is secured between a flange of a ring 49a integral with the upper section 18 and a flange of a ring 49b integral with the lower section 18. Each of the parts 48 and 49 consists of a single integral piece; the part 49 is mounted by annular clamps 52 locked against the flanges of rings 49a and 49b; the part 48 is assembled by bolting on the angle bars 48a and 48b.

The tapered lower end of each section 18 also performs a function of mechanical protection for the part 48 of joint 22.

Still in Figure 4, there is shown a projection 53 consisting of a metal annular half-tube, welded along an inner circumferencial portion of the barrel; it acts as a mechanical baffle or deflector to deviate the fluid threads of the ascending smoke stream.

Thus, the building up of eddies is avoided, and resulting possible deposits of unburnt substances in the discontinuity zone between the two barrels and possible jamming of the relative slidings.

The annulus between the inner band 48 and the outer band 49 is filled up before the assembling of part 49; generally, the filling 50 consists of mineral wool in flocks in order to ensure the highest thermal insulation.

In building yard, the annular bands 48 and 49 made up of various layers are supplied in a single, shaped, interrupted length; once installed, they are sealed by suitable adhesive in successive and offset layers; the upper and lower edges are beaded to prevent any possibility of tearing. The operation of the inner part 48 of the joint (which cannot be inspected) may be checked by the reading of gauges 54, indicating the pressure condition in the annulus between said bands 48 and 49. Still in Figure 4, there is shown a lug 52 of a plurality of lugs circumferentially spaced apart and used for the lifting of the sections. The lugs 52 could be internal instead of external of each section 18.

According to the present invention, in the toroidal chamber of the joint a guide system is accommodated consisting of a plurality of guide devices 24, generally four, arranged at the ends of two orthogonal diameters.

A description will now be given of a guide device 24, particularly referring to Figures 5 and 6, in which the joint 22 has been drawn in dashed lines only to show the position thereof.

The ring 49a, integral with the upper conduit section 18, is also integral with a guide rod 57 through a profiled section 56. Two pads or generally two guide rollers 58 and 60 engage on two opposite vertical walls 57' and 57"; particularly, each cage 62 has bolted thereto a flange 65 of a cylindrical body 66, which accommodates a stem 67 integral with a fork 68 carrying each roller 58 or 60; a pressure spring 70 acts on stem 67 between a bottom of cylinder 66 and a cap 69.

The guide system consisting of the devices 24 allows the vertical expansion of the conduits, assuring the congruency or correspondence of the sections of two successive conduit or barrel sections.

Possibly, measuring arrangements may be provided by pressure cells on the bolts to sense any stresses exceeding design stresses. Both the pressure control system for the annulus of the joint, and the stress control system for the guides can be connected to a signal or alarm system in a control room of the plant, as above referred to.

Thus, it will be appreciated that a chimney with a system of conduits is provided, each conduit consisting of isostatic sections hanging from the top, free from downward expansion, allowing the conduit to be arranged according to a broken line, for the horizontal deformations imparted by the outer reinforced concrete structure which is subjected to the forces of the outside agents.

The chimneys may be assembled according to the system provided in the earlier patent to the same applicant, which is here shortly summarized.

After providing for the construction of the outer structure 12 of reinforced concrete by a standard rampant mould (or slip-form) and forforming the brackets 13 with the suitable openings or discontinuities for the passage of the platforms 14, each platform is assembled and inserted at the chimney base, then it is lifted until it rests on the relative bracket beginning from the upper platform. Once the platforms have been positioned, the individual sections 18, previously insulated, of the smoke conveyance conduits, are mounted beginning from the upper section of each conduit. Finally, the sealing and expansion joints 22 are formed.

Of course, the foregoing is only illustrative and not limitative to the present invention and it should be understood that all of the changes within the reach of those skilled in the art can be made thereto, without departing for this from the covering field claimed by this application.

Claims (15)

1. Achimneycomprising: an outer supporting structure, inner platforms spaced apart along said structure, smoke conveyance conduits within said structure, each of said conduits consisting of conduit sections supported on the platforms, the adjoining conduit sections of a same conduit being connected by connecting joints, characterized in that each joint comprises a flexible inner band connected between adjacent ends of said two sections; a flexible outer safety band connected between adjacent ends of said two sections; and a filling of insulating material between said two bands.

2. A chimney according to Claim 1, characterized in that one end of a section adjacent to another section is extended by a tapered part to the other section.

3. A chimney according to Claim 1, characterized by further comprising in said section a circumferential inner projection near the upper end of said section.

4. A chimney accordin to Claim 1, characterized in that said inner band of the joint and said outer band of the joint are made of a plurality of layers.

5. A chimney according to Claim 1, characterized by further comprising in said section a circumferential inner projection near the upper end of said section.

6. A chimney according to Claim 2, characterized in that said outer band comprises a fabric of Teflon and fiber glass and nets of stainless steel.

7. A chimney according to Claim 1; characterized in that said joint is supplied in interrupted toroidal shape and said bands are beaded at the free end.

8. A chimney according to Claim 1, characterized by comprising a pressure measuring system within the filling ofthejoint.

9. A chimney according to Claim 1, characterized by comprising a guide system between successive adjoining sections, consisting of a plurality of devices distributed along a circumference at said joint.

10. A chimney according to Claim 9, characterized in that each said guide device comprises a rod integral with one said section supported parallel to the axis thereof and pressing elements supported on a cage integral with the other section and spring pressed against the rod by opposite parts thereof.

11. A chimney according to Claim 10, wherein said pressing elements are idle rollers.

12. Achimney according to Claim 1,characterized in that each said section is supported from the respective platform by suspension devices interposed between the platform intrados and the section, and circumferentially spaced apart around the section.

13. A chimney according to Claim 11, in which each suspension device comprises a member integral with the platform, a member integral with the section and a spring member interposed therebetween.

14. A chimney according to Claim 12, characterized in that said device comprises a cylinder integral with the platform, a stem sliding within the cylinder and extended externally thereof, an interposed spring forcing one end of the stem within the cylinder, the other end of the stem made integral with the conduit section, an insulating material being interposed between said stem and conduit.

15. A chimney substantially as hereinbefore described with reference to Figures 1 to 8 of the accompanying drawings.