GB1584399A

GB1584399A - Smoke-stack and method for erecting the same

Info

Publication number: GB1584399A
Application number: GB5409377A
Authority: GB
Original assignee: MARIANI BATTISTA SpA IMPRESA D
Current assignee: MARIANI BATTISTA SpA IMPRESA D
Priority date: 1977-08-11
Filing date: 1977-12-29
Publication date: 1981-02-11
Also published as: IT1042501B

Description

(54) A SMOKE-STACK AND METHOD FOR ERECTING THE SAME (71) We, MARIANA BATTISTA S.p.A.

IMPRESA DI COSTRUZIONI EDILI INDUSTRIALI of Via Cenisio 32-20154 Milan (Italy), a Company organized under the laws of Italy, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to the erection of industrial smoke-stacks having one or more metal ducts for the conveyance of smoke, such as that produced by a steam power plant or the like.

The necessity of having in up-to-date thermoelectric power plants a plurality of thermal units for providing the required power has involved, as is well known, the tendency by now generally followed of adopting smokestacks comprising an external supporting structure made of reinforced concrete, containing one or more inner ducts for smoke conveyance, each of which is connected to a proper power or generator unit. The external supporting structure accomplishes the task of withstanding the different external actions or stresses due to permanent loads, wind, earthquake, temperature, etc., while the inner ducts, generally made of steel, serve the only purpose of conveying the smoke being produced.

The principle followed at present is to form each of the inner ducts by means of a tubular barrel or liner which is structurally continuous throughout the smoke path and which can be laid at the foot or base portion of the smoke-stack, or otherwise hung from the top.

However, the use of continuous metal ducts involves substantial disadvantages, among which the following can be mentioned: difficult and prolonged assembly due to the considerable loads involved; at times insurmountable difficulties in maintenance; considerable and expensive constructive complications due to the unavoidable necessity of taking into account, at planning stage, such interactions as those between the external structure and inner duct or ducts with the resulting requrement of fitting up braces, sliders or other devices of a substantial cost; large thickness and accordingly considerable weight of the inner metal ducts, due to the necessity of taking into account more theoretical than practical elastic deformations, with a resulting wastage of material; inadequate use of internal control and maintenance platforms; load concentration at the base or at the top with obvious construction problems particularly in connection with the high thermal expansions that the entire duct is subjected to.

This invention aims to improve the construction of the above type of smoke-stacks, obviating or at least minimizing as far as possible the previously encountered difficulties.

According to the invention, there is provided an industrial smoke-stack comprising an external supporting structure platforms mounted internally of the structure, and one or more inner smoke conveyance ducts comprising a plurality of independent preformed sections each of which is supported by a platform, each section being joined to an adjacent one by a gas-tight coupling allowing relative movement between the sections.

According to the invention, there is also provided a method for erecting industrial smoke-stacks which comprises mounting, support platforms within an external structure, supporting preformed duct sections from each platform, and connecting each section with its adjacent section by means of a flexible gas-tight coupling.

With a smoke-stack made in accordance with the present invention, it will be possible to reduce assembling times, and facilitate maintenance operations, completely releasing the inner metal ducts from the interactions with the external supporting structure since thermal and mechanical stresses have been divided along the duct.

The invention will be further shown in the following with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal sectional view of a multiliner or multibarrel smoke-stack according to the invention; Fig. 2 is an enlarged cross-sectional view taken substantially along line 2-2 of Fig. 1; Fig. 3 is an enlarged fragmentary sectional view at a coupling between two adjoining sections of a smoke conveyance duct; and Figs. 4, 5 and 6 are views showing successive stages in the erection of the smoke-stack shown in Fig. 1.

Referring to Figs. 1-3, it will be seen that a smoke-stack according to the invention substantially comprises an external reinforced concrete structure 1 in the form of a tubular barrel, internally supporting metal ducts 2, each of which is connected to an associated thermal generator (not shown).

Internally of said external structure 1 and at predetermined levels, circular brackets 3 have been formed, with a metal platform 4 bearing on each of the latter and suitably shaped to accomodate the number of ducts 2 passing therethrough; each platform 4 serves both for inspection and maintenance of the smoke-stack and support for smoke conveyance ducts, as hereinafter explained.

As shown in Figs. 1 and 3, each of smoke conveyance ducts 2 comprise a plurality of duct sections 5 suitably interconnected by a sealing and expansion coupling 6, particularly shown in Fig. 3.

Each duct section 5 is carried at one end thereof by a respective supporting platform 4, for example being suspended at its top end, as shown, by bearing on cross stiffening brackets 7 (Fig. 3) fixed to each platform 4, as shown; thus, each duct section 5 is supported for free downward dilation and movement independently of the other duct sections 5.

As shown in the fragmentary sectional view of Fig. 3, each of the overlying duct sections have the bottom end 51 thereof inserted in the top end of the underlying duct section. Each section is suitably insulated by a layer of insulating material 8, as shown.

A practical embodiment of a sealing and expansion coupling 6 between adjoining duct sections is shown in Fig. 3.

As shown in Fig. 3, each coupling between adjoining sections comprises the formation of an annular trap 9 and a flexible sealing band 10 externally of the duct sections, as well as the introduction of a cord 11 of asbestos or other suitable material between the two inserted ends of the ducts, as shown.

Particularly, said annular trap comprises an annular tank 12 externally secured to the top end of the underlying duct section 5, which tank 12 is filled up, for example, with sand and boiled oil at a proper percentage. The trap is further completed with an annular metal blade 13 externally secured to the bottom end of the upper duct section, and which partly penetrates the sand in the underlying tank 12.

The coupling is further completed by said band 10, which comprises a padded cloth of reinforced double-layer asbestos, the cloth being gas seal secured between the upper edge of tank 12 and a supporting flange for said blade 13 of the sealing trap. Thus, a seal coupling is provided between adjoining duct sections capable of allowing free expansions and triaxial movements of the duct sections without transmitting any deformation stresses between the sections.Thus a smoke-stack is provided having a system of ducts, each of which formed by prefomred sections suspended at the top and free to expand downwards, or alternatively secured at the bottom and free to expand upwards, thereby enabling the ducts to be arranged in a non-linear manner to allow for the horizontal deformations imparted by the external reinforced concrete structure which is subjected to the forces of external agents.

Thus, the smoke-stack construction is considerably improved, facilitating maintenance operations, reducing the weight and cost thereof and dividing the thermal and mechanical stresses between the sections.

Fig. 3 shows also the use of lugs 14 that are secured internally of and adjacent the upper end of each duct section for lifting and positioning the sections, as hereinafter explained in connection with Figs. 4, 5 and 6 of the accompanying drawings.

After providing for erecting the external reinforced concrete structure 1 by conventional means and providing for forming said inner brackets 3 with suitable apertures for the passage of platform 4, the system for lifting the individual platforms is positioned by initially arranging oleodynamic (hydraulic) jacks 15 carrying lifting cables 16, directly on a slip-form 17 for the lifting of the upper platform, as shown. The platform is mounted and introduced at the base of the smokestack, then said cables 16 are hooked or attached, and the oleodynamic jacks 15 are operated to lift the platform 4 until the latter is brought to bear on the upper bracket. When the upper platform has been positioned, said oleodynamic jacks 15 are placed on said upper platform for lifting the underlying platform and/or platforms, as diagrammatically shown in Fig. 5.

Fig. 6 is a view showing the assembling of the individual sections 5 of the smoke conveyance ducts.

As shown in Fig. 6, the top section of each duct is first lifted and assembled, arranging said oleodynamic jacks 15 on a frame 20 directly bearing on top platform 4. After assembling of top sections 5, the underlying sections are lifted and assembled by descending cables 16 within previously assembled sections 5.

Upon completion of lifting and positioning operations for the individual duct sections 5, that have been suitably ground insulated, sealing and expansion couplings 6 are formed, first introducing asbestos cord 11 between the connected ends of adjoining ducts, then filling up trap 9 with sand and boiled oil, and finally mounting said blade 13. On completing seal trap, flexible seal band 10 is secured and then the insulating covering at the coupling zone is made.

Obviously, the matter above disclosed and shown in the accompanying drawings was given by way of unrestrictive example of the invention, while further variants can be made as to formation of seal coupling, lifting and bearing systems for the individual duct sections, without any change in the principle of the present invention which exactly consists of providing an industrial smoke-stack, wherein each of the smoke conveyance ducts are made of a plurality of sections independent of one another, each being carried by a respective supporting platform, and with the sections being interconnected by a gas seal coupling for allowing free deformations and relative movements between the sections both longitudinally of the smoke-stack and in transverse planes.

WHAT WE CLAIM IS: 1. An industrial smoke-stack comprising an external structure, platforms mounted internally of the structure, and one or more inner smoke conveyance ducts comprising a plurality of independent preformed sections each of which is supported by a platform, each section being joined to an adjacent one by a gas-tight coupling allowing relative movement between the sections.

2. A smoke-stack as claimed in claim 1 in which the duct sections are pre-formed tubes.

3. A smoke-stack as claimed in either of claims 1 or 2 in which the sections are supported at or near one end thereof.

4. A smoke-stack as claimed in claim 3 in which the sections are supported at the top ends thereof and are free for downward expansion.

5. A smoke-stack as claimed in claim 3 in which the sections are supported at their bottom ends and are free for upward expansion.

6. A smoke-stack as claimed in any one of claims 1 to 5 in which the platforms comprise metal frames.

7. A smoke-stack as claimed in claim 6 in which the sections are supported by brackets fixed to cross-members on the metal frames.

8. A smoke-stack as claimed in any of claims 1 to 7 in which each section has at its bottom end inner hooking lugs for attachment to lifting cables.

9. A smoke-stack as claimed in any of claims 1 to 8 in which the couplings comprise annular traps externally of the ends of adjoining sections.

10. A smoke-stack as claimed in claim 9 in which the trap comprises an annular channel adapted to contain a sealing medium surrounding the top of the lower section, and a sealing blade secured to the bottom of the upper section capable of depending into the sealing medium in the channel.

11. A smoke-stack as claimed in claim 10 in which the sealing medium is sand and boiled oil.

12. A smoke-stack as claimed in any of claims 1 to 11 in which the coupling comprises an annular band of flexible material externally secured between the adjacent ends of adjoining duct sections.

13. A smoke-stack as claimed in any of claims 1 to 12 in which the adjacent ends of duct sections are shaped to allow overlapping of adjoining sections and in which a sealing element is placed between the overlapping ends.

14. A smoke-stack as claimed in claim 13 in which the sealing element is an asbestos cord.

15. An industrial smoke-stack substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

16. A method of forming an industrial smoke-stack which comprises mounting support platforms within an external structure, supporting preformed duct sections from each platform, and connecting each section within adjacent section by means of a flexible gas-tight coupling.

17. A method as claimed in claim 16 in which the platforms are mounted in position from the top platform downwards using lifting cables from the top of the external structure.

18. A method as claimed in either of claims 16 or 17 in which the duct sections are supported in place from the top section downwards by means of lifting cables attached to suitable inner hooking lugs in the sections.

19. A method of forming an industrial smoke-stack substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. filling up trap 9 with sand and boiled oil, and finally mounting said blade 13. On completing seal trap, flexible seal band 10 is secured and then the insulating covering at the coupling zone is made. Obviously, the matter above disclosed and shown in the accompanying drawings was given by way of unrestrictive example of the invention, while further variants can be made as to formation of seal coupling, lifting and bearing systems for the individual duct sections, without any change in the principle of the present invention which exactly consists of providing an industrial smoke-stack, wherein each of the smoke conveyance ducts are made of a plurality of sections independent of one another, each being carried by a respective supporting platform, and with the sections being interconnected by a gas seal coupling for allowing free deformations and relative movements between the sections both longitudinally of the smoke-stack and in transverse planes. WHAT WE CLAIM IS:

1. An industrial smoke-stack comprising an external structure, platforms mounted internally of the structure, and one or more inner smoke conveyance ducts comprising a plurality of independent preformed sections each of which is supported by a platform, each section being joined to an adjacent one by a gas-tight coupling allowing relative movement between the sections.