Once-through boiler

Abstract

The present invention relates to a once-through boiler, more specifically comprising a casing formed to have a circular cross-section, a plurality of water tube sections provided within the casing along the longitudinal direction of the casing, and a header section provided within the casing and supporting the plurality of water tube sections, wherein the header section comprises an upper header provided on the upper part of the casing and a lower header provided spaced apart from the upper header, and wherein the plurality of water tube sections comprises a plurality of inner water tubes arranged concentrically between the upper header and the lower header, and a plurality of outer water tubes arranged concentrically spaced radially from the plurality of inner water tubes, wherein the plurality of inner water tubes and the plurality of outer water tubes are arranged radially with respect to the center of the casing, and the inner water tube adjacent to the inner water tube is arranged spaced apart by a predetermined interval, and the outer water tube adjacent to the outer water tube is arranged spaced apart by a predetermined interval.

Description

Technology Field

[0001] The present invention relates to a once-through boiler, and more specifically, to a once-through boiler in which a plurality of water tubes are arranged spaced apart from each other to account for the increase in diameter due to heating, and arranged with a spacing such that the water tubes adjacent to each other come into contact during expansion, so that the outer surface of the water tubes can act as a wall, thereby eliminating welding between the water tubes or wall configurations connecting the water tubes, and thus securing a space for the water tubes to be arranged, allowing for the arrangement of a larger number of water tubes and thus securing a larger evaporation capacity, and a once-through boiler that supports a plurality of water tubes through a donut-shaped header structure to have a higher operating pressure. Background Technology

[0002] Generally, a once-through boiler is classified as a forced-circulation boiler and refers to a type of boiler in which feedwater is pumped from one end of a long tube, heated, evaporated, and superheated sequentially along the way, and then sent as superheated steam to the other end of the tube. For example, Korean Registered Patent Publication No. 10-2229911 (March 22, 2021) discloses a once-through boiler equipped with a porous body combustor and a method of operating the same.

[0003] However, in the conventional cases described above, there was a problem in that the volume of the once-through boiler inevitably increased due to welding between water tubes or installing walls between them to prevent combustion gas leakage, and there were limitations on capacity expansion, such as increasing the number of water tubes. Prior art literature

[0004] Korean Patent Publication No. 10-2229911 (March 22, 2021) The problem to be solved

[0005] The present invention was devised to solve the problems of the prior art described above. Its purpose is to provide a once-through boiler capable of having a higher operating pressure by supporting multiple water tubes through a donut-shaped header structure. This is achieved by arranging multiple water tubes spaced apart from each other to account for the increase in diameter due to heating, and by arranging them with a spacing that ensures the water tubes are in contact with adjacent water tubes upon expansion, thereby allowing the outer surface of the water tubes to act as a wall. This eliminates the need for welding between water tubes or wall configurations connecting water tubes, thereby securing space for the water tubes to be arranged and enabling the placement of a larger number of water tubes.

[0006] The problems that the present invention aims to solve are not limited to those mentioned above, and other problems that the present invention aims to solve that are not mentioned herein will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0007] A once-through boiler according to a preferred embodiment of the present invention comprises a casing formed to have a circular cross-section, a plurality of water tube sections provided within the casing along the longitudinal direction of the casing, and a header section provided within the casing and supporting the plurality of water tube sections. The header section comprises an upper header provided on the upper part of the casing and a lower header provided spaced apart from the upper header. The plurality of water tube sections comprises a plurality of inner water tubes arranged concentrically between the upper header and the lower header, and a plurality of outer water tubes arranged concentrically spaced radially from the plurality of inner water tubes. The plurality of inner water tubes and the plurality of outer water tubes are arranged radially with respect to the center of the casing, and the inner water tube adjacent to the inner water tube is arranged spaced apart by a predetermined interval, and the outer water tube adjacent to the outer water tube is arranged spaced apart by a predetermined interval.

[0008] In addition, when the plurality of water pipes expand due to heating according to a preferred embodiment of the present invention, the outer surface of the inner water pipe and the outer surface of the adjacent inner water pipe come into contact, and the outer surface of the outer water pipe and the outer surface of the adjacent outer water pipe come into contact.

[0009] In addition, according to a preferred embodiment of the present invention, the spacing between the inner water pipe adjacent to the outer water pipe is formed to be longer than the spacing between the outer water pipe adjacent to the outer water pipe.

[0010] In addition, according to a preferred embodiment of the present invention, the upper header comprises an upper inner header formed in a donut shape on the upper portion of the plurality of inner water pipes and an upper outer header formed in a donut shape on the upper portion of the plurality of outer water pipes, and the lower header comprises a lower inner header formed in a donut shape on the lower portion of the plurality of inner water pipes and a lower outer header formed in a donut shape on the lower portion of the plurality of outer water pipes.

[0011] In addition, the upper inner header, upper outer header, lower inner header, and lower outer header according to a preferred embodiment of the present invention are characterized by being formed to have a circular cross-section. Effects of the invention

[0012] By means of the solution to the above problem, the once-through boiler of the present invention arranges a plurality of water tubes spaced apart from each other to account for the increase in diameter due to heating, and arranges them with a spacing such that the water tubes adjacent to each other come into contact during expansion, thereby allowing the outer surface of the water tubes to act as a wall, thus eliminating welding between the water tubes or wall configurations connecting the water tubes, thereby securing space for the water tubes to be arranged, which allows for the arrangement of a larger number of water tubes and thus secures a larger evaporation capacity, and has the effect of providing a once-through boiler capable of having a higher operating pressure by supporting a plurality of water tubes through a donut-shaped header structure.

[0013] The effects of the present invention are not limited to those mentioned above, and effects of the present invention not mentioned herein will be clearly understood by those skilled in the art to which the present invention belongs from the description below. Brief explanation of the drawing

[0014] FIG. 1 is a diagram showing the configuration of a once-through boiler according to a preferred embodiment of the present invention. FIG. 2(a) is a drawing showing the inner water tube and the outer water tube of a once-through boiler according to a preferred embodiment of the present invention arranged concentrically with spaced apart from each other, and FIG. 2(b) is a drawing showing the header portion of a once-through boiler according to a preferred embodiment of the present invention provided on the upper part of the water tube portion in a ring shape or a donut shape. FIG. 3 is a drawing showing a comparison of the appearance of the inner water tube of a once-through boiler before and after expansion according to a preferred embodiment of the present invention. FIG. 4(a) is a drawing showing the arrangement of the outer water tubes of a once-through boiler according to a preferred embodiment of the present invention, and FIG. 4(b) is a drawing showing the arrangement of the inner water tubes of a once-through boiler according to a preferred embodiment of the present invention. FIG. 5 is a drawing showing the actual manufactured appearance of the water tube section and header section of a once-through boiler according to a preferred embodiment of the present invention. Specific details for implementing the invention

[0015] The terms used in this specification will be briefly explained, and the invention will be described in detail.

[0016] The terms used in this invention have been selected based on currently widely used general terms while considering their functions within the invention; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Therefore, the terms used in this invention should be defined not merely by their names, but based on their meanings and the overall context of the invention.

[0017] When a part of a specification is described as “comprising” a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0018] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0019] Specific details regarding the problem to be solved by the present invention, the means for solving the problem, and the effects of the invention are included in the embodiments and drawings described below. The advantages and features of the present invention, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the accompanying drawings.

[0020] In the case of a conventional vertical water-tube multi-tube once-through boiler, upper and lower headers are installed within the casing at a fixed vertical interval. Between these upper and lower headers, multiple vertical water tubes are connected concentrically using longitudinal fins to form an inner and outer row of water tubes, thereby creating a combustion gas passage. Additionally, heat transfer fins are typically welded horizontally to the combustion gas passages of the inner and outer rows of water tubes. However, to prevent combustion gas leakage, the volume of the once-through boiler inevitably increases due to welding between the tubes or the installation of walls between them. Furthermore, in the case of the upper and lower headers installed above and below the conventional water tubes to support them, the operating pressure is 3 kg / cm² due to the low evaporation capacity. 2 Up to 10kg / cm 2 A header with a relatively lower elliptical structure has been applied.

[0021] Accordingly, the once-through boiler of the present invention increases the number of water tubes by omitting welding or walls between multiple water tubes and increases the operating pressure of the upper and lower headers supporting the water tubes, thereby ultimately increasing the evaporation capacity. The feedwater supply pipe (400), high-temperature water and steam discharge pipe (500), combustion gas discharge duct (600), burner (700), and combustion chamber (800) disclosed in the drawings are conventional once-through boiler components, so a detailed description is omitted.

[0022] Hereinafter, the present invention will be described in more detail with reference to the attached drawings.

[0023] Referring to FIG. 1 and FIG. 2, a once-through boiler according to a preferred embodiment of the present invention comprises a casing (100) formed to have a circular cross-section, a plurality of water tube sections (200) provided inside the casing (100) along the longitudinal direction of the casing (100), and a header section (300) provided inside the casing (100) and supporting the plurality of water tube sections (200). Here, the casing (100) is cylindrical in shape, partitions the inside and outside, and has a combustion chamber (800) formed inside, and serves to protect the plurality of water tube sections (200) and the header section (300) provided inside, and a detailed description is omitted as it is a conventional once-through boiler configuration.

[0024] And, the header section (300) includes an upper header (310) provided on the upper part of the casing (100) and a lower header (320) provided spaced apart from the upper header (310). Here, the header section (300) serves to support the plurality of water pipe sections (200), and the plurality of water pipe sections (200) are supported by being arranged vertically on the ground between the upper header (310) and the lower header (320). That is, the upper end of the plurality of water pipe sections (200) is connected to the upper header (310), and the lower end is connected to the lower header (320) to be supported.

[0025] Next, the plurality of water pipe sections (200) include a plurality of inner water pipes (210) arranged concentrically between the upper header (310) and the lower header (320), and a plurality of outer water pipes (220) arranged concentrically and spaced radially from the plurality of inner water pipes (210). Here, the plurality of water pipe sections (200) are arranged concentrically with respect to the center of the casing (100).

[0026] Additionally, the upper header (310) includes an upper inner header (311) formed in a donut shape on the upper portion of the plurality of inner water pipes (210), and an upper outer header (312) formed in a donut shape on the upper portion of the plurality of outer water pipes (220). Furthermore, the lower header (320) includes a lower inner header (321) formed in a donut shape on the lower portion of the plurality of inner water pipes (210), and a lower outer header (322) formed in a donut shape on the lower portion of the plurality of outer water pipes (220). At this time, the upper inner header (311), upper outer header (312), lower inner header (321), and lower outer header (322) are formed to have a circular cross-section.

[0027] That is, referring to FIG. 2(b), the header portion (300) is formed in a ring shape with a hollow formed in its inner circumference and is configured to cover the upper and lower surfaces of the water pipe portion (200), respectively, thereby enabling a higher operating pressure. Here, the header portion (300) is formed to have a width greater than the diameter of the water pipe portion (200) when expanded, and referring to [Table 1] below, the 3 to 10 kg / cm² of a conventional elliptical header structure 2 Maximum pressure of 96 kg / cm², approximately 100 times higher than the operating pressure 2 The operating pressure can be secured.

[0028] division Vowel Header Section 65A (Sch. 160) Maximum operating pressure P MPa 9.5 Inner diameter of the fuselage plate D mm 53.99 Allowable tensile stress s a N / mm 2 118 texture - - SA106 Gr.B Longitudinal joint efficiency η1 - 1 Efficiency of tube pore heat η2 - 0.483 K value K - 0.4 Attachment α mm 1 Calculated thickness tr mm 6.000 When η = 1 th mm 3.284 Nominal thickness t mm 9.52 Tolerance on the specification (-) side - mm 1.19 Actual head tn mm 8.33 minimum thickness tm mm 6 examine 8.33 > 6 9.52 > 6

[0029] Meanwhile, the plurality of inner water pipes (210) and the plurality of outer water pipes (220) are arranged radially with respect to the center of the casing (100), and the inner water pipes (210) adjacent to the inner water pipes (210) are arranged at a spaced interval of a predetermined interval, and the outer water pipes (220) adjacent to the outer water pipes (220) are arranged at a spaced interval of a predetermined interval. Accordingly, when the plurality of water pipe sections (200) expand due to heating, the outer surface of the inner water pipe (210) and the outer surface of the adjacent inner water pipe (210) come into contact, and the outer surface of the outer water pipe (220) and the outer surface of the adjacent outer water pipe (220) come into contact.

[0030] More specifically, the inner water pipe (210) and the adjacent inner water pipe (210) are spaced apart at intervals of 0.24 mm to 0.26 mm. At this time, if the inner water pipe (210) and the adjacent inner water pipe (210) are spaced apart at intervals of less than 0.24 mm, there is a problem in that the inner water pipe (210) or the adjacent inner water pipe (210) are plastically deformed and damaged, such as by changing the diameter or becoming dented, as the inner water pipe (210) and the adjacent inner water pipe (210) expand due to heating.

[0031] That is, referring to FIG. 3, the inner water pipe (211) before expansion, which is before the operation of the once-through boiler of the present invention, changes into the inner water pipe (211) after expansion as its diameter increases after operation and is heated. At this time, the inner water pipe (211) after expansion and the adjacent inner water pipe (211) after expansion are designed to come into contact at a single point of contact (213), thereby minimizing the gap between the inner water pipe (211) after expansion and the adjacent inner water pipe (211) after expansion, so that the leakage of combustion gas can be minimized.

[0032] In addition, if the inner water pipe (210) and the adjacent inner water pipe (210) are spaced apart by a gap exceeding 0.26 mm, there is a problem in that the amount of combustion gas leakage increases as the inner water pipe (211) after expansion and the adjacent inner water pipe (211) after expansion do not come into contact. Therefore, the inner water pipe (210) and the adjacent inner water pipe (210) are spaced apart by a gap of 0.24 mm to 0.26 mm.

[0033] Likewise, the outer water pipe (220) and the adjacent outer water pipe (220) are spaced apart at intervals of 0.19 mm to 0.21 mm. At this time, if the outer water pipe (220) and the adjacent outer water pipe (220) are spaced apart at intervals of less than 0.19 mm, there is a problem in that the outer water pipe (220) or the adjacent outer water pipe (220) are plastically deformed and damaged, such as by changing the diameter or becoming dented, as the outer water pipe (220) and the adjacent outer water pipe (220) expand due to heating.

[0034] That is, referring to FIG. 3, the outer water pipe (221) before expansion, which is before the operation of the once-through boiler of the present invention, changes into the outer water pipe (222) after expansion as its diameter increases after operation and is heated. At this time, by designing the outer water pipe (222) after expansion and the adjacent outer water pipe (222) after expansion to meet at one point, the gap between the outer water pipe (222) after expansion and the adjacent outer water pipe (222) after expansion can be minimized, thereby minimizing the leakage of combustion gas.

[0035] In addition, if the outer water pipe (220) and the adjacent outer water pipe (220) are spaced apart by more than 0.21 mm, there is a problem in that the amount of combustion gas leakage increases as the outer water pipe (222) after expansion and the adjacent outer water pipe (222) after expansion do not come into contact. Therefore, the outer water pipe (220) and the adjacent outer water pipe (220) are spaced apart by 0.19 mm to 0.21 mm.

[0036] NO item unit Driving Conditions-1 Driving Conditions-2 note 1 Boiler pressure / steam temperature kg / cm 2 g 60 / 275.4 140 / 335.7 saturated steam 2 Coefficient of linear expansion of the material (carbon steel) mm / degC 0.0000127 0.0000131 Refer to KS B 6750 Table C.4.2 3 Reference temperature degC 20.0 20.0 Room temperature standard 4 Operating temperature degC 275.4 335.7 - 5 temperature difference degC 255.4 315.7 (4)-(3) 6 Thermal expansion rate mm 0.0033 0.0041 (2)×(5) 7 Length of the material mm 60.3 60.3 outer diameter of the crown 8 Expansion length of the material mm 0.20 0.25 (6)×(7)

[0037] As previously explained, the spacing between the inner water pipe (210) and the inner water pipe (210) adjacent to the outer water pipe (220) is formed to be longer than the spacing between the outer water pipe (220) and the adjacent outer water pipe (220). For example, referring to FIG. 4 (a) and [Table 2], the spacing between the center of the outer water pipe (221) before expansion and the adjacent outer water pipe (221) before expansion can be formed to be 60.5 mm, and the outer water pipe (221) before expansion and the adjacent outer water pipe before expansion are spaced at a 6° angle and arranged in a total of 60. Also, the spacing between the outer surface of the outer water pipe (221) before expansion and the adjacent outer water pipe before expansion (221) is formed to be 0.2 mm. Arranged in this manner, the expanded outer water pipe (222) comes into contact with the adjacent expanded outer water pipe (222).

[0038] Additionally, referring to FIG. 4(b), the spacing between the inner water pipe (211) before expansion and the adjacent inner water pipe (211) before expansion can be formed to be 60.5 mm, and the inner water pipe (211) before expansion and the adjacent inner water pipe (211) before expansion are spaced apart at an angle of 7.2° and arranged in a total of 50. Also, the spacing between the inner water pipe (211) before expansion and the adjacent inner water pipe (211) before expansion is formed to be 0.25 mm. Arranged in this way, the inner water pipe (212) after expansion comes into contact with the adjacent inner water pipe (212) after expansion.

[0039] As a result, the once-through boiler of the present invention arranges multiple water tubes spaced apart from each other to account for the increase in diameter due to heating, and arranges them with a spacing such that adjacent water tubes come into contact with each other upon expansion. Consequently, the outer surface of the water tube can act as a wall, thereby eliminating the need for welding between water tubes or wall configurations connecting water tubes. This secures space for the water tubes, allowing for the arrangement of a larger number of water tubes and thus securing a larger evaporation capacity. Additionally, it has the advantage of supporting multiple water tubes through a donut-shaped header structure, thereby enabling a higher operating pressure.

[0040] As such, those skilled in the art to which the present invention pertains will understand that the technical configuration of the present invention described above can be implemented in other specific forms without altering the technical concept or essential features of the present invention.

[0041] Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting, and the scope of the invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the invention.

[0042] The present invention discloses a high-pressure once-through boiler in which an upper header and a lower header are installed at a certain distance from each other using standard pipes (water tubes) inside and outside the casing to enable the production of high-temperature and high-pressure hot water and steam, and a plurality of inner and outer vertical water tubes are arranged concentrically between the upper header and the lower header, thereby forming a combustion gas passage without separate welded airtight parts (membrane walls or spacers, etc.).

[0043] Conventional once-through boilers have upper and lower headers shaped like concentric circles or squares, allowing them to operate only at temperatures below 10 kg / cm²-g (183 degrees). However, the headers of this small high-pressure boiler use pipes of worldwide standard, enabling operation at up to 140 kg / cm²-g (335 degrees). Therefore, when operating in industrial facilities requiring high temperature and pressure, it is possible to operate safely and simply in terms of equipment and operation without using large water-tube boiler types.

[0044] In addition, conventional once-through boilers consist of a longitudinally welded airtight wall (membrane wall) or a welded heat transfer groove structure (spacer) between the inner and outer vertical water tubes, but this small high-pressure boiler maintains gas tightness with a Tangential Wall (Tube-Tube) between the vertical water tubes without separate welded airtight parts, thus having a more compact structure compared to conventional sizes. Explanation of the symbols

[0045] 100 : Casing 200 : Crown 210 : Internal water pipe 211: Inner water pipe before expansion 212: Inner water pipe after expansion 213 : Contact 220 : External water pipe 221 : External water pipe before expansion 222 : External water pipe after expansion 300 : Header section 310 : Top header 311 : Upper inner header 312 : Upper outer header 320 : Subheader 321 : Lower inner header 322 : Lower outer header 400: Water supply pipe 500: High-temperature water and steam discharge pipe 600 : Combustion gas exhaust duct 700 : Burner 800: Combustion chamber

Claims

Claim 1 A casing formed to have a circular cross-section; a plurality of water pipe sections provided within the casing along the longitudinal direction of the casing; and a header section provided within the casing and supporting the plurality of water pipe sections; wherein the header section includes an upper header provided on the upper part of the casing; and a lower header provided spaced apart from the upper header; wherein the upper header includes an upper inner header formed in a donut shape on the upper part of the plurality of inner water pipes; and an upper outer header formed in a donut shape on the upper part of the plurality of outer water pipes; and wherein the lower header includes a lower inner header formed in a donut shape on the lower part of the plurality of inner water pipes. and a lower outer header formed in a donut shape at the lower part of the plurality of outer water pipes; wherein the upper inner header, upper outer header, lower inner header, and lower outer header are formed to have a circular cross-section, and the plurality of water pipes comprises a plurality of inner water pipes arranged concentrically between the upper header and the lower header; and a plurality of outer water pipes arranged concentrically and spaced radially from the plurality of inner water pipes; wherein the plurality of inner water pipes and the plurality of outer water pipes are arranged radially with respect to the center of the casing, and the inner water pipes adjacent to the inner water pipes are arranged spaced apart at intervals of 0.24 mm to 0.26 mm, and the outer water pipes adjacent to the outer water pipes are arranged spaced apart at intervals of 0.19 mm to 0.21 mm, and the spacing distance between the centers of the outer water pipes adjacent to the outer water pipes is formed to be 60.5 mm, and the outer water pipes adjacent to the outer water pipes are arranged spaced apart at an angle of 6°, and the spacing distance between the centers of the inner water pipes adjacent to the inner water pipes is formed to be 60.5 mm, and the inner water pipes adjacent to the inner water pipes are arranged spaced apart at an angle of 7.2°, and when the plurality of water pipe sections expand due to heating, the A once-through boiler characterized by the outer surface of an inner water pipe and the outer surface of an adjacent inner water pipe coming into contact, and the outer surface of an outer water pipe and the outer surface of an adjacent outer water pipe coming into contact. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete

Images