WO2017175040A1

WO2017175040A1 - A nozzle for a circulating fluidized bed (cfb) boiler

Info

Publication number: WO2017175040A1
Application number: PCT/IB2016/053813
Authority: WO
Inventors: Subramaniam Chiramadam RAMANATHAN; Radhe S JHA; Devkumar Fulchand GUPTA; Ramakrishna Ramanath SONDE
Original assignee: Thermax Ltd
Current assignee: Thermax Ltd
Priority date: 2016-04-08
Filing date: 2016-06-27
Publication date: 2017-10-12
Anticipated expiration: 2018-10-08
Also published as: PH12018502308A1

Abstract

A nozzle for a circulating fluidized bed (CFB) boiler of the present disclosure relates to the field of mechanical engineering. The nozzle creates resistance to ingress of fine solid particles and maintains uniform air distribution therethrough. The nozzle has a body having a predetermined thickness and at least one passage configured along the thickness of the body such that, the passage extends from an inner surface of the body and terminates at an outer surface of the body. The passage facilitates the flow of a fluid from a lumen formed within the body to the outer surface of the body and vice versa. The passage has at least one bend. The bend restricts the backflow of fine solid particles through the nozzle to avoid the disturbance to the air flow pattern by the fine solid particles within the windbox.

Description

A NOZZLE FOR A CIRCULATING FLUIDIZED BED (CFB) BOILER

FIELD

The present disclosure relates to the field of mechanical engineering. Particularly, the present disclosure relates to the field of nozzles. BACKGROUND

Conventional nozzles, used to supply air in a combustion chamber of circulating fluidized bed boilers, have an inclined structure with respect to a furnace of the boiler. During variation in the load of the boiler, fine solid particles tend to travel back to a furnace plenum of the boiler via internal profile of the conventional nozzle. The conventional nozzle has a plurality of inclined holes configured on the surface thereof. The inclined holes are not sufficient to counter backflow of the fine solid particles from a combustion chamber to the windbox of the boiler. The fine solid particles can easily travel upwards through the inclination. The fine solid particles enter the nozzle via the plurality of holes, and eventually get entrained in the furnace plenum of the boiler. The ingress of the fine solid particles into the furnace plenum leads to reduction in circulating fluidized bed inventory. Further, the ingress of fine solid particles disturbs the air flow pattern within the windbox of circulating fluidized bed based boilers.

Therefore, there is felt a need to develop a nozzle that alleviates the abovementioned drawbacks and prevents the backflow of fine solid particles therethrough. OBJECTS

Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:

An object of the present disclosure is to provide a nozzle that supplies air in a combustion chamber of a circulating fluidized bed boiler. Another object of the present disclosure is to provide a nozzle that creates resistance to ingress of fine solid particles.

Yet another object of the present disclosure is to provide a nozzle that maintains uniform air distribution therethrough. Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

SUMMARY

A nozzle for a circulating fluidized bed (CFB) boiler is disclosed. The nozzle has a lumen, which is closed at an operative end, and a body defined by an operative inner surface and an operative outer surface. The nozzle has at least one passage that commences from a first opening configured at the inner surface of the body, and terminates at a second opening configured at the outer surface of the body of the nozzle. The at least one passage facilitates flow of a fluid from the lumen to the outer surface of the nozzle. The at least one passage is characterized by having at least one bend.

In an embodiment, the at least one passage has three portions, viz., a first portion, a second portion, and a third portion. The first portion extends outwardly from the first opening, and has a longitudinal axis orthogonal to a longitudinal axis of the lumen. The second portion extends outwardly from the first portion, and has a longitudinal axis inclined to the longitudinal axis of the first portion at a predetermined angle. The third portion extends outwardly from the second portion, and has a longitudinal axis parallel to the longitudinal axis of the first portion, and inclined to the longitudinal axis of the second portion at a predetermined angle.

In another embodiment, the at least one passage has two portions, viz., a first portion, and a second portion. The first portion extends outwardly from the first opening, and has a longitudinal axis inclined to a longitudinal axis of the lumen. The second portion extends outwardly from the first portion, and has a longitudinal axis orthogonal to the longitudinal axis of the body.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING A nozzle for a circulating fluidized bed (CFB) boiler of the present disclosure will now be described with the help of the accompanying drawing, in which:

Figure 1 illustrates a schematic view of the nozzle, in accordance with an embodiment of the present disclosure; and Figure 2 illustrates a schematic view of the nozzle, in accordance with another embodiment of the present disclosure.

List of Reference Numerals

100 - Nozzle

102a - Body

102b - Lumen

103a - Operative inner surface

103b - Operative outer surface

104 - Passage

104a - First opening

104b - Second opening

105a, 105b - Pairs of passages

106 - First portion

107 - Branch point

108 - Second portion

110 - Third portion

112 - Operative open end

114 - Operative closed end

L - Longitudinal axis of the lumen

LI - Longitudinal axis of the first portion

L2 - Longitudinal axis of the second portion

L3 - Longitudinal axis of the third portion Θ1 - Predetermined angle between LI and L2 Θ2 - Predetermined angle between L2 and L3 200 - Nozzle 202a - body 202b - Lumen

203a - Operative inner surface 203b - Operative outer surface 204 - Passage 204a - First opening 204b - Second opening

205a, 205b - Pairs of passages

206 - First portion

207 - Branch point

208 - Second portion 212 - Operative open end 214 - Operative closed end Θ3 - Predetermined angle between LI and L DETAILED DESCRIPTION

The present disclosure envisages a nozzle for a circulating fluidized bed (CFB) boiler that restricts the backflow of fine solid particles therethrough.

The nozzle, of the present disclosure, has a body and at least one passage. The nozzle has a lumen closed at an operative end, and is configured to facilitate the flow of a fluid therethrough. The body has an operative inner surface and an operative outer surface. The body is defined by an operative open end and an operative closed end. The at least one passage is configured in the body such that the at least one passage commences from a first opening configured at an inner surface of the body and terminates at a second opening configured at an outer surface of the body. The at least one passage facilitates the flow of a fluid, preferably a fluidized medium, from the lumen to the outer surface of the body. The at least one passage is characterized by having at least one bend. The bend restricts the backflow of fine solid particles through the nozzle, thereby avoiding the disturbance to the air flow pattern by the fine solid particles within a windbox.

The nozzle, of the present disclosure, is now described with reference to figure 1 and figure 2.

Figure 1 illustrates a schematic view of a nozzle 100, in accordance with an embodiment of the present disclosure. The nozzle 100 has a body 102a and a lumen 102b configured therein. The lumen 102b extends from an operative open end 112 and terminates at an operative closed end 114 of the body 102a. The nozzle 100 has at least one passage 104 configured along the thickness of the body 102a. The at least one passage 104 commences from a first opening 104a configured at an operative inner surface 103a of the body 102a, and terminates at a second opening 104b configured at an operative outer surface 103b of the body 102a. The at least one passage 104 facilitates flow of a fluid therethrough. In an embodiment, the fluid is a fluidized medium used in a circulating fluidized bed (CFB) boiler. The at least one passage 104 has at least one bend 108.

In an embodiment, the at least one passage 104 has three portions, viz., a first portion 106, a second portion 108, and a third portion 110. The first portion 106 extends outwardly from the first opening 104a such that the longitudinal axis LI of the first portion 106 is orthogonal to the longitudinal axis L of the lumen 102b. The second portion 108, which is the bent portion, extends outwardly from the first portion 106 such that the longitudinal axis L2 of the second portion 108 is inclined to the longitudinal axis LI of the first portion 106 at a predetermined angle Θ1.

In an exemplary embodiment, the predetermined angle Θ1 between the longitudinal axis LI of the first portion 106 and the longitudinal axis L2 of the second portion 108 is in the range of 25 to 60 degrees. The third portion 110 extends outwardly from the second portion 108 and terminates at the second opening 104b such that, the longitudinal axis L3 of the third portion 110 is parallel to the longitudinal axis LI of the first portion 106. Further, the longitudinal axis L3 of the third portion 110 is inclined to the longitudinal axis L2 of the second portion 108 at a predetermined angle Θ2.

In an exemplary embodiment, the predetermined angle Θ2 between the longitudinal axis L2 of the second portion 108 and the longitudinal axis L3 of the third portion 110 is in the range of 25 to 60 degrees.

In another exemplary embodiment, the distance between the center of the first portion 106 and the center of the third portion 110 is in the range of 3 to 10 mm.

The cross-sectional shape of the body 102a, the first portion 106, the second portion 108, and the third portion 110 can be selected from the group consisting of a circle, a square, a rectangle, a triangle, and any combinations thereof. In a preferred embodiment, the first portion 106, the second portion 108, and the third portion 110 have a circular cross-section having a diameter in the range of 3 to 6 mm. The body 102a is formed by a casting process having a circular cross-section having a diameter in the range of 25 to 65 mm and the distance between the operative inner surface 103a and the operative outer surface 103b is in the range of 4 mm to 10 mm.

In a preferred embodiment, the first opening 104a and the second opening 104b have a circular shape.

In yet another embodiment, the nozzle 100 has a plurality of passages 104 formed along the thickness of the body 102a. The plurality of passages 104 is configured in a form of pairs of passages depicted as pair 105a and pair 105b. One passage of each pairs of passages 105a, 105b is positioned opposite to another passage of the same pair of passages 105a, 105b such that, both the passages of the pairs of passages 105a, 105b are at the same longitudinal distance from the operative open end 112 of the body 102a. Each passage of the pairs of passages 105a, 105b is in fluid communication with the lumen 102b via a branch point 107, as shown in figure 1. In a preferred embodiment, the distance between the two consecutive pairs of passages, i.e., between the pair of passages 105a and the pair of passages 105b is in the range of 5 to 20 mm. In a preferred embodiment, the nozzle 100 is manufactured by a casting process.

In an operative configuration, the operative open end 112 of the nozzle 100 is coupled with the windbox (not shown in figures). The lumen 102b of the nozzle 100 receives a fluid, preferably a fluidized medium, from the windbox. The nozzle 100 delivers the fluid received to a space within a combustion chamber (not shown in figures) of the boiler, preferably a circulating fluidized bed (CFB) boiler (not shown in figures), via at least one passage 104. During the load variation, the fluid from the combustion chamber tends to enter the nozzle via the passage 104. This backflow of fluid typically contains fine solid particles. The inclined configuration of the second portion 108 restricts the backflow of the fine solid particles that may occur due to varying the load of the CFB boiler. The velocity of the fine solid particles is reduced and the fine solid particles are agglomerated within the passage 104 due to the inclination of the second portion 108. The fine solid particles are drained back to the combustion chamber by gravity. Thus, the fine solid particles are unable to enter the windbox. Therefore, the air distribution within the windbox is uniformly maintained and the circulating fluidized bed inventory is saved.

Figure 2 illustrates a schematic view of a nozzle 200, in accordance with another embodiment of the present disclosure. The nozzle 200 has a body 202a and a lumen 202b configured therein. The lumen 202b extends from an operative open end 212 and terminates at an operative closed end 214 of the body 202a. The nozzle 200 has at least one passage 204 configured along the thickness of the body 202a. The at least one passage 204 extends from a first opening 204a configured at an inner surface 203a of the body 202a, and terminates at a second opening 204b configured at an outer surface 203b of the body 202a. The at least one passage 204 facilitates flow of a fluid therethrough. In an embodiment, the fluid is a fluidized medium used in a circulating fluidized bed (CFB) boiler. The at least one passage 204 has at least one bend 206.

In an embodiment, the at least one passage 204 has two portions, viz., a first portion 206 and a second portion 208. The first portion 206, which is the bend, extends outwardly from the first opening 204a, and has a longitudinal axis LI inclined to the longitudinal axis L of the lumen 202b at a predetermined angle Θ3. In an exemplary embodiment, the predetermined angle Θ3 between the longitudinal axis LI of the first portion 206 and the longitudinal axis L of the lumen 202b is in the range of 25 to 60 degrees.

The second portion 208 extends outwardly from the first portion 206 and terminates at the second opening 204b. Further, the second portion 208 has the longitudinal axis L2 orthogonal to the longitudinal axis L of the lumen 202b.

The cross-sectional shape of the body 202a, the first portion 206, and the second portion 208 can be selected from the group consisting of a circle, a square, a rectangle, a triangle, and any combinations thereof. In a preferred embodiment, the first portion 206 and the second portion 208 have a circular cross-section having a diameter in the range of 3 to 6 mm. In another embodiment, the body 202a is formed by a casting process having a circular cross-section having a diameter in the range of 25 to 65 mm and the distance between the inner surface 203a and the outer surface 203b is in the range of 4 mm to 10 mm.

In a preferred embodiment, the first opening 204a and the second opening 204b have a circular shape.

In yet another embodiment, the nozzle 200 has a plurality of passages 204 formed along the thickness of the body 202a. The plurality of passages 204 are configured in a form of pairs of passages depicted as pair 205a and pair 205b. One passage of each pair of passages 205a, 205b is positioned opposite to another passage of the same pair of passages 205a, 205b such that both the passages of the pairs of passages 205a, 205b are at the same longitudinal distance from the operative open end 212 of the body 202a. Each passage of the pairs of passages 205a, 205b is in fluid communication with the lumen 202b via a branch point 207, as shown in figure 2. In a preferred embodiment, the distance between the two consecutive pairs of passages, i.e., the pair of openings 205a and the pair of openings 205b, is in the range of 5 to 20 mm.

In an embodiment, the nozzle 200 is manufactured by a casting process.

In an operative configuration, the operative open end 212 of the nozzle 200 is coupled with the windbox (not shown in figures). The lumen 202b of the nozzle 200 receives a fluid, preferably a fluidized medium, from the windbox. The nozzle 200 delivers the fluid received to a space within a combustion chamber of a boiler, preferably a circulating fluidized bed (CFB) boiler (not shown in figures), via at least one passage 204. During the load variation, the fluid from the combustion chamber tends to enter the nozzle via the passage 204. This backflow of fluid typically contains fine solid particles. The inclined configuration of the first portion 206 restricts the backflow of the fine solid particles that may occur due to varying the load of the CFB boiler. The velocity of the fine solid particles is reduced and the fine solid particles are agglomerated within the passage 204 due to the inclination of the second portion 208. The fine solid particles are drained back to the combustion chamber by gravity. Thus, the fine solid particles are unable to enter the windbox. Therefore, the air distribution within the windbox is uniformly maintained and the circulating fluidized bed inventory is saved. TECHNICAL ADVANCEMENTS

The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a nozzle for a circulating fluidized bed (CFB) boiler that:

• creates resistance to ingress of fine solid particles; and

• maintains uniform air distribution therethrough. The disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The foregoing description of the specific embodiments so fully revealed the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

A nozzle (100, 200) for a circulating fluidized bed (CFB) boiler, said nozzle (100, 200) defining a lumen (102b, 202b) closed at an operative end (114, 214) and a body (102a, 202a) defined by an operative inner surface (103a, 203a) and an operative outer surface (103b, 203b), said nozzle having at least one passage (104, 204) commencing from a first opening (104a, 204a) configured at said operative inner surface (103a, 203a), and terminating at a second opening (104b, 204b) configured at said operative outer surface (103b, 203b), said at least one passage (104, 204) facilitating flow of a fluid from said lumen (102b, 202b) to said outer surface (103b, 203b) of said nozzle (100, 200), wherein said at least one passage (104, 204) is characterized by having at least one bend (108, 206) along its length.

The nozzle as claimed in claim 1, wherein said passage (104) is defined by a first portion (106), a second portion (108), and a third portion (110) such that: said first portion (106) extends outwardly from said first opening (104a), and has a longitudinal axis (LI) orthogonal to a longitudinal axis (L) of said lumen (102b); said second portion (108) extends outwardly from said first portion (106), and has a longitudinal axis (L2) inclined to said longitudinal axis (LI) of said first portion (106) at a predetermined angle (Θ1); and said third portion (110) extends outwardly from said second portion (108) terminating at said second opening (104b), and has a longitudinal axis (L3) parallel to said longitudinal axis (LI) of said first portion (106), and inclined to said longitudinal axis (L2) of said second portion (108) at a predetermined angle

(Θ2).

The nozzle as claimed in claim 1, wherein said passage (204) is defined by a first portion (206), and a second portion (208) such that: said first portion (206) extends outwardly from said first opening (204a), and has a longitudinal axis (LI) inclined to a longitudinal axis (L) of said lumen (202b) at a predetermined angle

(Θ3); and said second portion (208) extends outwardly from said first portion (206) terminating at said second opening 204b, and has a longitudinal axis (L2) orthogonal to said longitudinal axis (L) of said lumen (202b).

4. The nozzle as claimed in claim 2, wherein said body (102a), said first portion (106), said second portion (108), and said third portion (110) have a cross section selected from the group consisting of a circle, a square, a rectangle, a triangle, and any combinations thereof.

5. The nozzle according to claim 4, wherein said first portion (106), said second portion (108), and said third portion (110) have a circular cross-section having diameter in the range of 3 to 6 mm.

6. The nozzle according to claim 2, wherein said predetermined angle (Θ1) between said longitudinal axis (LI) of said first portion (106) and said longitudinal axis (L2) of said second portion (108), and said predetermined angle (Θ2) between said longitudinal axis (L2) of said second portion (108) and said longitudinal axis (L3) of said third portion (110) is in the range of 25 to 60 degrees.

7. The nozzle as claimed in claim 3, wherein said body (202a), said first portion (206), said second portion (208) have a cross-section selected from the group consisting of a circle, a square, a rectangle, a triangle, and any combinations thereof.

8. The nozzle as claimed in claim 4 or claim 7, wherein said body (102, 202) is formed by a casting process having a circular cross-section having diameter in the range of 25 to 65 mm.

9. The nozzle as claimed in claim 1, wherein the distance between said operative inner surface (103a, 203a) and said operative outer surface (103b,203b) is in the range of 4 mm to 10 mm.

10. The nozzle as claimed in claim 3, wherein said first portion (206) and said second portion (208) have a circular cross-section having diameter in the range of 3 to 6 mm.

11. The nozzle as claimed in claim 3, wherein said predetermined angle (Θ3) between said longitudinal axis (LI) of said first portion (206) and said longitudinal axis (L) of said lumen (202b) is in the range of 25 to 60 degrees.

12. The nozzle as claimed in claim 1, wherein said nozzle (100, 200) has a plurality of passages (104, 204), wherein said plurality of passages (104, 204) are configured to form pairs of passages (105a, 105b, 205a, 205b) such that passages (104, 204) of each of said pairs (105a, 105b, 205a, 205b) branching from said inner surface (103a, 203a) at respective branch points (107, 207) positioned opposite to each other to be at the same longitudinal distance from an operative open end (112, 212) of the body (202).

13. The nozzle as claimed in claim 12, wherein distance between two consecutive pairs of passages (105a, 105b, 205a, 205b) is in the range of 5 mm to 20 mm.

14. The nozzle as claimed in claim 1, wherein said first opening (104a, 204a) and said second opening (104b, 204b) have a circular cross-sectional shape.

15. The nozzle as claimed in claim 2, wherein distance between the center of the first portion 106 and the center of the third portion 110 is in the range of 3 to 10 mm.