Enhanced heat transfer element and fuel oil gas boiler with enhanced heat transfer element as heat exchange assembly

Abstract

The invention relates to an enhanced heat transfer element and a fuel oil gas boiler using the enhanced heat transfer element as a heat exchange assembly, and aims to improve the heat transfer efficiency and the energy-saving effect of the boiler. The boiler comprises a burner, a hearth, a membrane type water cooling wall, a convection heat exchange assembly and the like. A convection heat exchange assembly composed of a group of enhanced heat transfer elements is arranged around the center of a hearth in a central symmetry or axial symmetry mode, each heat transfer element is composed of a vertical light pipe and bent pin fins which are perpendicular to the root of the outer wall of the vertical light pipe and evenly distributed, the center lines of all the bent pin fins are perpendicular to the center line of the vertical light pipe, and therefore the smoke flowing path is optimized; and the heat exchange effect is enhanced. And particularly, the free ends of the bent pin fins can form a tight embedded arrangement or diffusion structure, so that the transverse and longitudinal scouring of flue gas is effectively improved, a flowing dead zone is reduced, and the heat transfer efficiency is improved. By means of the design, the heat efficiency of the boiler is effectively improved, energy consumption and environmental emission are reduced, and the boiler is suitable for high-efficiency operation of fuel oil and gas boilers.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel oil and gas boiler equipment, and in particular to a fuel oil and gas boiler having a heat transfer enhancement element and a heat transfer enhancement element as a heat exchange component thereof. Technical Background As an important thermal energy conversion and utilization equipment, oil-fired gas boilers play a vital role in the energy conversion and utilization process. Among them, the design of heat transfer elements and heat exchangers as heat exchange components is directly related to the safety and operational stability of oil-fired gas boilers.

[0002] Take the invention patent CN200580011479.8 applied by Aalborg Industries Ltd. as an example ( Figure 1a ), the traditional vertical water-tube oil-fired gas boiler with tube sheet, the flame after the oil and gas combustion is biased to one side of the tube sheet, there is a large temperature gradient between the high-temperature tube sheet area where the flame directly radiates and the low-temperature tube sheet area where the convection tube bundle transfers heat, and the flue gas obliquely scours the heat transfer elements and fins. The flame bias leads to low flame fullness and a loose furnace structure; the large temperature gradient makes the tube sheet prone to cracking; the flue gas obliquely scours the heat transfer elements and fins, resulting in reduced heat transfer efficiency, and the boiler is large in size. The above problems seriously affect the safe operation and low-carbon green and high-quality development of oil-fired gas boilers.

[0003] Take the invention patent CN110425511B applied by Zhejiang Liju Thermal Equipment Co., Ltd. as an example ( Figure 1b ), a surface burner is arranged on one side of the furnace wall, which causes the flue gas temperature on the surface burner side of the furnace to be too high, forming a high-temperature tube sheet area. After the flue gas is heat exchanged through the convection tube bundle, a low-temperature tube sheet area is formed in the low-temperature convection tube bundle area. The large temperature gradient before and after can easily lead to cracks in the tube sheet.

[0004] Take the invention patent CN212841492U applied by Borite Thermal Equipment Co., Ltd. as an example ( Figure 1c ), a surface burner is also arranged on the furnace wall on one side of the furnace. The three-stage water pipe arrangement causes the flue gas to form an obvious temperature gradient distribution, forming a high-temperature tube sheet area close to the burner side and a low-temperature tube sheet area of ​​two sections of low-temperature convection tube bundles, which affects the boiler's pressure bearing capacity.

[0005] The above three structures all have local asymmetric high-temperature areas on the tube sheet. The uneven distribution of thermal stress on the tube sheet can easily cause deformation of the tube sheet, leading to cracks in the welds between the water tube and the tube sheet, endangering the long-term safe operation of the boiler. Summary of the invention

[0006] In order to solve the above problems, the present invention provides an enhanced heat transfer element and its application in an oil-fired gas boiler, aiming to improve the heat transfer efficiency of the boiler. By moving the convection heat exchange tube bundle out of the furnace, the convection heat exchange tube bundle is arranged externally or symmetrically, the temperature gradient is optimized and the thermal stress concentration is reduced. By designing and arranging a group of enhanced heat transfer elements in the convection heat exchange tube bundle, the heat exchange effect between the flue gas and the heat exchange tube is significantly improved. The enhanced heat transfer element is composed of a vertical light tube and a curved pin fin evenly distributed on the outer wall of the tube bundle, which optimizes the flue gas oblique flushing of the pin fin to full positive flushing, optimizes the flue gas flow path, and improves the flushing effectiveness. The free ends of the pin fins are curved and diffuse or closely embedded, which can effectively reduce the flue gas corridor caused by uneven gap flow, enhance the horizontal and vertical flushing effect between the flue gas and the tube wall, and thus improve the efficiency of convection heat exchange. The close arrangement of the enhanced heat transfer elements ensures that the distance between the pin fins and the light tubes in each tube bundle is closer, and the combined curved pin fin structure is adopted to further optimize the arrangement between the pin fins. This not only increases the heat transfer area per unit volume, but also avoids excessive gaps between the pin fins, thereby improving the heat transfer efficiency and overall heat exchange effect, ensuring the efficiency and safety of the boiler equipment in long-term operation. In addition, the design of the enhanced heat transfer element also avoids the common flow dead zone in the traditional heat exchange tube bundle, improving the overall thermal efficiency and stability of the boiler. This technical solution provides an effective solution for the high-efficiency operation of oil and gas boilers, reducing energy consumption and emissions.

[0007] In order to achieve the above-mentioned object, the present invention provides an enhanced heat transfer element and a fuel gas boiler using the enhanced heat transfer element as a heat exchange component, comprising a burner, a furnace, an upper steam drum, a membrane water-cooled wall of a lower header and a downcomer; a convection heat exchange tube bundle is arranged outside the furnace, and the two ends of the convection heat exchange tube bundle are respectively connected to the upper steam drum and the lower header; the burner is arranged in the upper steam drum, and the fuel and air are mixed in the burner and ignited and burned to form a diffusion or premixed flame that fills the furnace space; the upper steam drum and the lower header are cylindrical structures as a whole, and are respectively connected by an upper tube plate, a lower tube plate and a cylindrical shell, and the upper steam drum and the lower header are circumferentially connected to the membrane water-cooled wall; the cross section of the convection heat exchange tube bundle is annular from the furnace to the outside; the space surrounded by the lower tube plate of the upper steam drum, the upper tube plate of the lower header, the membrane water-cooled wall, and the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle close to the flame constitutes a furnace filled with flames.

[0008] Furthermore, the convection heat exchange tube bundle is arranged in a centrally symmetrical manner as a whole; the upper steam drum and the lower header are annular headers, which are respectively connected by an annular upper tube plate, a lower tube plate and concentric cylindrical shells with different inner and outer diameters, and the combustion port is arranged in the center of the upper steam drum; the cross-section of the convection heat exchange tube bundle is a circular cross-section from the furnace to the outside, and the ring line parts on both sides of the circular ring adopt a membrane water-cooled wall structure; the space surrounded by the lower tube plate of the upper steam drum, the upper tube plate of the lower header, the membrane water-cooled wall, and a row of membrane water-cooled wall tubes of the convection heat exchange tube bundle close to the flame constitutes the furnace; the flue gas burning in the furnace descends and turns 90 degrees from the bottom flue gas inlet of the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle close to the flame and flows into the convection heat exchange tube bundle.

[0009] Furthermore, the convection heat exchange tube bundle includes a plurality of enhanced heat transfer elements, which are arranged in parallel to form a heat exchange zone. The periphery of the heat exchange zone surrounded by the plurality of enhanced heat transfer elements adopts a membrane water-cooled wall structure. Along the direction in which the smoke enters the heat exchange zone, the cross section of the heat exchange zone gradually decreases or the enhanced heat exchange tubes in the heat exchange zone are arranged symmetrically, with a smoke inlet arranged at the bottom facing the smoke surface and a smoke outlet arranged at the top away from the smoke surface. The plurality of enhanced heat exchange tubes adopt enhanced heat transfer elements. The enhanced heat transfer elements include light pipes, and heat exchange fins are arranged on the outer surface of the light pipes. The heat exchange fins are a plurality of curved pin fins or plate fins, and a structure in which the pin fins and the plate fins are mutually embedded and staggered on the same horizontal plane, a structure in which the pin fins and the plate fins are mutually staggered on different horizontal planes, a structure in which the plate fins and the plate fins are mutually staggered, or a tile-shaped fin is adopted, and the length of both ends or one end is set to the light pipe; the curved pin fin includes a root, a curved section and a free section, the root is along the normal direction of the light pipe surface, and the curved section connects the root and the free section.

[0010] Furthermore, four straight wings are arranged on the outer surface of the light tube along two mutually perpendicular diameter directions, and a bent pin wing is arranged between two adjacent straight wings, and the free end of the bent pin wing is bent in the counterclockwise direction or the clockwise direction in the cross section of the light tube.

[0011] Furthermore, the roots of the bent pin fins are distributed radially, the free ends of the bent pin fins are bent and parallel to each other, and the spacing between the parallel sections is the same; short straight pin fins are also arranged on the outer wall of the light tube, and the short straight pin fins are arranged radially along the light tube, and the bent pin fins and the short straight pin fins are symmetrically distributed on the outside of the outer light tube about the center plane of the light tube.

[0012] Furthermore, four straight fins are arranged on the outer surface of the light tube along two mutually perpendicular diameter directions, and a bent pin fin is arranged between two adjacent straight wings. The free ends of the bent pin fins are bent at a set angle toward the straight wings located in the same horizontal plane, and the free ends of the pin fins form a quadrilateral contour on the same horizontal plane; two adjacent rows of enhanced heat exchange tubes can be arranged in series or staggered.

[0013] Furthermore, the upper steam drum and the lower header are cylindrical structures as a whole, which are respectively connected by an upper tube plate, a lower tube plate and a cylindrical shell. The upper steam drum and the lower header are circumferentially connected to the membrane water-cooled wall; the cross-section of the convection heat exchange tube bundle is a trapezoidal cross-section from the furnace to the outside; the space surrounded by the lower tube plate of the upper steam drum, the upper tube plate of the lower header, the membrane water-cooled wall, and the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle close to the flame constitutes a furnace filled with flames.

[0014] Furthermore, the convection heat exchange tube bundle is respectively connected to the upper steam drum and the lower header through the external header of the boiler body.

[0015] Furthermore, the external enhanced heat transfer element surrounds the middle boiler body in a ring shape, and the upper steam drum and the lower header are each provided with a connecting pipe to connect the external upper steam drum and the external lower header.

[0016] Furthermore, the upper tube sheet of the steam drum and the lower tube sheet of the lower header are flat tube sheets, ellipsoidal tube sheets or arched tube sheets. When the ellipsoidal tube sheets or arched tube sheets are used as land-based oil and gas boilers with small water level fluctuations, straight tie rods can be omitted when the ellipsoidal tube sheets are selected; when the arched tube sheets are selected, straight tie rods can be omitted in the surrounding areas, but straight tie rods still need to be set in the central area.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: by arranging enhanced heat transfer elements in the convection heat exchange tube bundle of the boiler, the present invention optimizes the flue gas flow path and improves the heat exchange and airflow distribution inside the boiler. The unique structure of the enhanced heat transfer elements can effectively prevent the problems of uneven heat, overheating or cold spots in the traditional design, and ensure the stable operation of the boiler under different working conditions. This design not only improves the safety of the boiler, but also prolongs the service life of the equipment, reduces the maintenance frequency, and reduces the operation risk. The present invention effectively reduces the phenomenon of over-combustion of fuel by improving the heat transfer efficiency of the boiler, thereby reducing the emission of harmful substances in the flue gas. More efficient thermal energy utilization means less fuel consumption, which in turn reduces the emission of greenhouse gases and pollutants, meeting modern environmental protection requirements. This technology can provide a low-emission, high-efficiency solution for industrial boilers, helping companies meet environmental standards, reduce environmental pollution, and promote the development of green and low-carbon technologies; Furthermore, the heat exchange element organically combines the flue gas scouring the curved pin fins horizontally and the vertical smooth tube walls vertically to form a convective heating surface that synergistically enhances the heat exchange by scouring horizontally and vertically. The heat transfer element optimizes the heat conduction between the flue gas and the tube wall through the curved pin fins and the vertical smooth tubes. The geometric structure and arrangement of the curved pin fins make the lateral and longitudinal flow of the flue gas more uniform, avoiding the dead zone problem common in traditional designs, ensuring uniform heat exchange in all areas of the boiler, and helping to significantly improve the overall heat transfer effect of the boiler, and helping to further improve the thermal efficiency of the boiler.

[0018] The present invention arranges enhanced heat transfer elements in the convection heat exchange tube bundle to improve the heat exchange efficiency of the boiler. The enhanced heat transfer elements are used to enhance the heat exchange between the flue gas and the heat exchange tubes, thereby improving the thermal energy utilization rate of the boiler. By optimizing the flue gas flow path and enhancing the heat exchange effect, the same fuel can be converted into thermal energy in a shorter time, thereby reducing fuel consumption. This not only improves energy utilization and reduces boiler operating costs, but also helps reduce dependence on fossil energy, thereby promoting the realization of sustainable energy use and energy conservation and emission reduction goals. Furthermore, the fin type of the heat transfer enhancement element may also be other optional plate fin and pin fin structures, using a structure in which plate fins and pin fins are staggered on different horizontal planes; a structure in which plate fins and plate fins are staggered to enhance the turbulence of flue gas; tile-shaped fins may also be used to cut a tube bundle with a smaller diameter in half and connect them to a central tube bundle to increase the heat exchange area.

[0019] Furthermore, the free ends of the bent pin fins can form a closely packed heat exchange tube bundle group in which hexagonal pin fins are embedded in each other. The free ends of the pin fins are embedded in each other, the structures overlap, and the arrangement is compact. This can reduce the flue gas corridor formed by the uneven gap flow caused by the excessive opening angle of the free ends of the pin fins, increase the flue gas flow rate, and improve the convection enhanced heat exchange effect of the bent pin fin enhanced heat exchange element.

[0020] Four straight wings are arranged on the outer surface of the light tube along two mutually perpendicular diameter directions, and a curved pin wing is arranged between two adjacent straight wings. The free ends of the curved pin wing are bent at a set angle toward the straight wing located in the same horizontal plane. The rectangular structure is formed by two pin wing of different lengths. The root of the long wing extends radially, and the free end is bent in the horizontal direction. The free ends of each pin wing are equidistant and parallel to each other. The short straight wing extends radially, and the free end is on the same horizontal line with the long curved pin wing.

[0021] Furthermore, four straight fins are arranged on the outer surface of the light tube along two mutually perpendicular diameter directions, and a bent pin fin is arranged between two adjacent straight wings. The free ends of the bent pin fins are bent in a counterclockwise or clockwise direction in the cross section of the light tube, and the eight bent pin fins on the same horizontal plane form an octagonal structure. The straight fins and the free ends of the bent pin fins of each tube bundle are embedded in the straight fins and the free ends of the pin fins of the adjacent tube bundles, and the arrangement is compact, thereby improving the convection enhanced heat exchange effect of the bent pin fin enhanced heat exchange element.

[0022] Furthermore, in order to reduce tube sheet cracks caused by thermal stress, the convection heat exchange tube bundle is moved out of the furnace, and a connecting pipe connected to the external upper steam drum and the external lower header is opened on the same side of the cylindrical shell of the upper steam drum and the lower header; the steam generated by the external enhanced heat transfer element is introduced into the upper steam drum of the boiler body through the steam pipe above the external upper steam drum. The external enhanced heat transfer element can reduce tube sheet cracks and deformation caused by thermal stress in the furnace tube sheet, making the boiler run more safely and effectively extending the service life of the boiler.

[0023] Furthermore, the upper tube sheet of the steam drum can adopt an ellipsoidal raised tube sheet, and the connection process can adopt manual arc welding, which is suitable for thick-walled materials and occasions without special requirements for welding position, and is commonly used for low-pressure components in boiler manufacturing; gas shielded welding, which is commonly used for thinner pipes and pressure components in boilers; argon arc welding, which is commonly used for precision welding parts in boiler manufacturing; submerged arc welding, which is mainly used for components in boilers that withstand high pressure and high temperature, and is suitable for welding large-diameter pipes and thick-walled boiler pressure vessels; laser welding, which is used for welding parts with high precision requirements, especially for welding high-performance materials and thin-walled components; electroslag welding, which is suitable for welding large-diameter, thick-walled pressure vessels and boiler pipes in boilers; spot welding and riveting welding, spot welding is often used for connecting thin plates and thin-walled components, and riveting welding is more common in the early connection process of boilers.

[0024] The enhanced heat transfer element of the present invention is not only suitable for oil and gas boilers, but also can be adapted to various types of boiler systems, with strong design flexibility. The enhanced heat transfer element can be optimized and adjusted according to the use requirements and working conditions of the boiler to meet the heat transfer requirements of industrial boilers of different sizes and types. In addition, the technology can also customize the geometric shape and layout of the heat transfer element according to specific needs, adapting to a wider range of industrial application scenarios, and improving the applicability and market competitiveness of boiler equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1a It is a schematic diagram of the structure of a traditional vertical water-tube oil-fired gas boiler including a tube sheet; Figure 1b This is a schematic diagram of the structure of arranging a surface burner on one side of the furnace wall of the prior art furnace; Figure 1c A schematic diagram of the prior art showing a surface burner arranged on the furnace wall on one side of the furnace, and a three-stage water pipe arrangement to form a clear temperature gradient distribution of the flue gas.

[0026] Figure 2a The invention discloses a side cross-sectional view of an oil-fired gas boiler using an enhanced heat transfer tube bundle and the bundle as a heat exchange component.

[0027] Figure 2b The present invention is a top view of a cross-sectional view of an enhanced heat transfer tube bundle and a fuel gas boiler using the bundle as a heat exchange component.

[0028] Figure 2c This is a top view of a cross-sectional view of another enhanced heat transfer tube bundle of the present invention and a fuel gas boiler using the bundle as a heat exchange component.

[0029] Figure 3a The figure is a side view of another implementable enhanced heat transfer tube bundle of the present invention and a fuel gas boiler using the bundle as a heat exchange component.

[0030] Figure 3b This is a top view of a cross-sectional view of another embodiment of the present invention, which is an enhanced heat transfer tube bundle and a fuel gas boiler using the bundle as a heat exchange component.

[0031] Figure 4a A convective heat exchange tube bundle of a heat transfer enhancement element of the present invention is a hexagonal pin-fin and a cross-sectional view.

[0032] Figure 4b A convective heat exchange tube bundle of a heat transfer enhancement element of the present invention is a hexagonal plate fin and a cross-sectional view.

[0033] Figure 5 This is a cross-sectional view of a convection heat exchange tube bundle of a heat transfer enhancement element of the present invention, in which hexagonal pin-fins are embedded with each other.

[0034] Figure 6a This is a cross-sectional view of a convective heat exchange tube bundle of a heat transfer enhancement element of the present invention, which is arranged in a quadrilateral pin-fin staggered pattern.

[0035] Figure 6b This is a cross-sectional view of a convective heat exchange tube bundle of a heat transfer enhancement element of the present invention, in which quadrilateral pin-fins are arranged in series.

[0036] Figure 7a This is a cross-sectional view of a convection heat exchange tube bundle of a heat transfer enhancement element of the present invention in a rectangular pin-fin shape.

[0037] Figure 7b This is a three-dimensional diagram of a convection heat exchange tube bundle of a heat transfer enhancement element of the present invention in a rectangular pin-fin shape.

[0038] Figure 8 This is a cross-sectional view of a convective heat exchange tube bundle of a heat transfer enhancement element of the present invention, in which octagonal pin-fins are arranged in series.

[0039] Figure 9a The top cross-sectional view is another practicable enhanced heat transfer tube bundle of the present invention and a fuel gas boiler using the bundle as a heat exchange component.

[0040] Figure 9b A top view of another implementable enhanced heat transfer tube bundle of the present invention and a fuel gas boiler using the bundle as a heat exchange component.

[0041] Fig.10a This is a three-dimensional diagram of another implementable enhanced heat transfer tube bundle of the present invention and a fuel oil and gas boiler using the bundle as a heat exchange component.

[0042] Fig.10b A top view of another implementable enhanced heat transfer tube bundle of the present invention and a fuel gas boiler using the bundle as a heat exchange component.

[0043] Fig.10c The present invention is another practicable enhanced heat transfer tube bundle and a side cross-sectional view of a fuel oil and gas boiler using the bundle as a heat exchange component.

[0044] Fig.11 Schematic diagram of some other optional wing types in the present invention.

[0045] Fig.12 This is a definition diagram of pin fins and plate fins in the present invention.

[0046] Fig.13a It is a pin-fin bending component in the present invention.

[0047] Fig.13b A partial view of a pin-fin bending component in the present invention.

[0048] In the attached drawings, 1-burner, 2-furnace, 3-upper steam drum, 4-lower header, 5-membrane water-cooled wall, 6-down pipe, 7-convective heat exchange tube bundle, 11-steam outlet, 12-lower tube sheet of upper steam drum, 13-upper tube sheet of lower header, 14-pull rod, 15-baffle, 16-refractory material, 17-steam outlet pipe, 31-external upper steam drum, 41-external lower header. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] In the description of the present invention, it is necessary to understand that the terms "center", "up", "down", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0051] In order to solve the problems of the existing technology, the design of enhanced heat transfer elements has become an effective technical means. By adding enhanced heat transfer elements to the convection heat exchange tube bundle, the heat exchange effect can be significantly improved and the overall thermal efficiency of the boiler can be improved. These enhanced heat transfer elements can not only improve the heat exchange capacity between the flue gas and the tube wall, but also optimize the flue gas flow path, reduce the flow dead zone and local overheating, and thus improve the safety and reliability of the boiler.

[0052] The core innovation of this technical solution is to arrange enhanced heat transfer elements with specific structures in the convection heat exchange tube bundle with a trapezoidal cross section. These heat transfer elements are designed with curved pin-fins and other structures to optimize the flow path of the flue gas and enhance the heat exchange effect between the flue gas and the heat exchange tube. In particular, in the enhanced heat transfer elements, the geometric shape and arrangement of the pin-fins are used to effectively improve the horizontal and vertical flushing effect of the flue gas, enhance the heat conduction capacity, and avoid the uneven flow and dead zone phenomenon that may occur in traditional designs.

[0053] refer to Figure 2aThe boiler shown includes a burner 1, a furnace 2, an upper drum 3, a lower header 4, a membrane water-cooled wall 5, a downcomer 6 and a convection heat exchange tube bundle 7; the burner 1 is arranged in the upper drum 3, and the fuel and air are mixed in the burner 1 and ignited and burned to form a diffusion or premixed flame that fills the furnace space 2; the upper drum 3 and the lower header 4 are cylindrical structures as a whole, and are respectively connected by an upper tube sheet, a lower tube sheet and a cylindrical shell, and the upper and lower ends of the cylindrical shell are respectively connected to the upper tube sheet and the lower tube sheet, and the upper tube sheet of the upper drum 3 and the lower header 4 The upper and lower tube sheets are provided with a plurality of straight tie rods 14 to support the upper and lower tube sheets to prevent the tube sheets from being deformed and bulged under pressure. The lower header 4 between the upper steam drum 3 is circumferentially connected with a membrane water-cooled wall 5; the cross section of the convection heat exchange tube bundle 7 is an annular cross-sectional structure from the furnace 2 to the outside, with the lower bottom edge of the trapezoid near the furnace and the upper bottom edge of the trapezoid far from the furnace; the convection heat exchange tube bundle 7 is wrapped around with a membrane water-cooled wall structure composed of a light tube + flat steel, a group of enhanced heat transfer elements are arranged inside the membrane water-cooled wall structure, and the bottom of the membrane water-cooled wall structure near the furnace is left A flue gas inlet is provided, and a flue gas outlet is reserved at the upper part of the membrane water-cooled wall structure far from the furnace side; the space surrounded by the lower tube sheet of the upper steam drum 1, the upper tube sheet of the lower header 4, the membrane water-cooled wall 5, and the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle 7 close to the flame constitutes a furnace 2 filled with flames; the flue gas burning in the furnace descends from the gap where the flat steel is not provided at the bottom of the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle 7 close to the flame, turns 90 degrees, and flows into the convection heat exchange tube bundle 7; after the flue gas enters the area where the convection heat exchange tube bundle 7 is located, it first horizontally flushes the convection heat exchange tube bundle 7, and then flows into the convection heat exchange tube bundle 7; The bottom of the heat tube bundle 7 is then turned 90 degrees and flows vertically upward to longitudinally flush the outer wall of a group of vertical light tubes of enhanced heat transfer elements arranged in the center of the counter-current heat exchange tube bundle 7, and at the same time horizontally flush the pin fins connected to the outer wall of the vertical light tube to the top and is discharged from the flue gas outlet on the other side; the boiler feed water enters from the upper steam drum 3, enters the lower header 4 through the downcomer 6, and is evenly distributed. The feed water is heated by the membrane water wall 5 and the counter-current heat exchange tube bundle 7 respectively, and is heated into a steam-water mixture, and then flows upward to the upper steam drum 3, and supplies heat to users from the steam outlet 11.

[0054] refer to Figure 2b , for the above Figure 2a From the top view, the cross section of the convection heat exchange tube bundle 7 is an annular cross section structure from the furnace to the outside. The inner and outer rings are wrapped by a membrane water-cooled wall structure composed of a light tube + flat steel. A group of enhanced heat transfer elements are arranged in the center of the ring. The lower tube plate of the upper steam drum 3, the upper tube plate of the lower header 4, the membrane water-cooled wall 5, and the space surrounded by the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle 7 close to the flame constitute a furnace 2 filled with flames.

[0055] refer to Figure 2c , for the above Figure 2b Another feasible top view is to arrange the downcomers between the convection heat exchange tube bundles 7 to reduce the furnace floor space.

[0056] refer to Figure 3a , including an upper steam drum 3, a lower header 4, a membrane water-cooled wall 5, a downcomer 6 and a convection heat exchange tube bundle 7; the gas and air are mixed in the burner and ignited to form a diffusion or premixed flame that fills the furnace space 2; the flue gas burning in the furnace space descends and turns 90 degrees from the bottom flue gas inlet of the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle 7 close to the flame to flow into the convection heat exchange tube bundle 7; after entering the convection heat exchange tube bundle 7, the flue gas first flushes the bottom of the convection heat exchange tube bundle 7 horizontally, and then turns 90 degrees to flow vertically upward The outer wall of a group of vertical light tubes of enhanced heat transfer elements arranged in the center of the counter-current heat exchange tube bundle 7 is flushed, and at the same time, the pin fins connected to the outer wall of the vertical light tube are flushed horizontally to the top and discharged from the flue gas outlet on the other side. The boiler feed water enters from the upper steam drum 3, enters the lower header through the downcomer 6, and is evenly distributed. The feed water is heated by all the membrane water-cooled walls 5 and the counter-current heat exchange tube bundle 7, and is heated into a steam-water mixture, which flows upward to the upper steam drum and supplies heat to users from the steam outlet 11. The downcomer 6 is arranged outside the upper steam drum 3 and the lower header 4.

[0057] refer to Figure 3b The upper steam drum 3 and the lower header 4 are annular headers as a whole, and the structure is that the outer ring of the annular upper tube plate and the annular lower tube plate are connected to the cylindrical shell, and the inner ring of the annular upper tube plate and the annular lower tube plate are connected to the cylindrical shell to be closed. The upper steam drum 3 and the lower header 4 are connected with two inner and outer layers of membrane water-cooled walls 5 around the circle; the cross section of the convection heat exchange tube bundle 7 is a circular cross-sectional structure from one side of the furnace to the outside, and the inner and outer sides of the circular ring are membrane water-cooled walls 5. A group of enhanced heat transfer elements are arranged between the two layers of membrane water-cooled walls 5 of the annular structure; the space surrounded by the lower tube plate 12 of the upper steam drum, the upper tube plate 13 of the lower header, the outer ring of the membrane water-cooled wall 5, and the inner ring of the membrane water-cooled wall tube row close to the flame constitutes a furnace 2 filled with flames; the downcomer arrangement can also be adopted Figure 2c Built-in down pipe arrangement; refer to Figure 4a A group of enhanced heat exchange elements connected with bent pin fins are evenly arranged in the center of the trapezoidal cross section of the convection heat exchange tube bundle 7, which are connected between the lower tube sheet of the upper drum 3 and the upper tube sheet of the lower header 4. The free ends of the bent pin fins can form a hexagonal structure to form a heat exchange tube bundle group. The enhanced heat exchange element organically combines the flue gas scouring the bent pin fins horizontally and the vertical smooth tube wall vertically to form a convection heating surface that synergistically enhances the heat exchange by scouring horizontally and vertically. refer to Figure 4bA group of enhanced heat exchange elements connected with curved plate fins are evenly arranged at the center of the trapezoidal cross-section of the convective heat exchange tube bundle 7, which are connected between the lower tube sheet of the upper steam drum 3 and the upper tube sheet of the lower header 4. The free ends of the curved plate fins enable the enhanced heat exchange elements to form a hexagonal structure. Multiple enhanced heat exchange elements can form a close-packed structure to form a heat exchange tube bundle group. The heat exchange component organically combines the flue gas scouring the curved plate fins horizontally and the vertical smooth tube wall longitudinally to form a convective heating surface that synergistically enhances the heat exchange by scouring horizontally and longitudinally.

[0058] refer to Figure 5 A group of enhanced heat exchange elements connected with bent pin fins are evenly arranged at the center of the trapezoidal cross section of the convective heat exchange tube bundle 7, which are connected between the lower tube sheet of the upper steam drum 3 and the upper tube sheet of the lower header 4. The free ends of the bent pin fins can form a closely packed heat exchange tube bundle group in which hexagonal pin fins are embedded with each other. The free ends of the pin fins and the gaps are embedded with each other, the structures overlap, and the arrangement is compact, which can reduce the flue gas corridor formed by the non-uniform gap flow caused by the excessive opening angle of the free ends of the pin fins. This can increase the flue gas flow rate and improve the convective enhanced heat exchange effect of the enhanced heat exchange elements of the bent pin fins.

[0059] refer to Figure 6a The convective heat exchange tube bundle is arranged in a staggered manner. The center of the trapezoidal cross-section of the convective heat exchange tube bundle 7 is evenly arranged to connect a group of enhanced heat exchange elements between the lower tube sheet of the upper steam drum 3 and the upper tube sheet of the lower header 4. The enhanced heat exchange elements are provided with bent pin fins. The free ends of the bent pin fins can form a quadrilateral structure to form a heat exchange tube bundle group. Four pin fins along two mutually perpendicular diameter directions are straight wings. Two bent pin fins of equal length are evenly arranged within the 90° angle formed by the straight wings. The free ends of the bent pin fins are respectively bent to set angles in the direction of the straight wings located in the same horizontal plane. The free ends of the pin fins form a quadrilateral contour on the same horizontal plane to evenly distribute the flue gas.

[0060] refer to Figure 6b The shape of the enhanced heat exchange element is the same as Figure 6a , arranged in series, Figure 6a The tube bundle with quadrilateral fins is rotated 90° with the center line of the tube bundle as the axis, and then the tube bundle is densely arranged. The two curved pin-fins in the 90° angle space between the two straight wings are slightly bent outward to reduce the excessive flue gas channels in the up, down, left and right directions of the tube bundle when arranged in series, which affects the heat exchange effect.

[0061] refer to Figure 7a, short straight pin fins and multiple curved pin fins are arranged on the outside of the light tube, the roots of the curved pin fins and the short straight pin fins of the convection heat exchange tube bundle 7 are distributed radially, the free ends of the curved pin fins are bent and parallel to each other, the spacing of the parallel sections is the same, the curved pin fins and the short straight pin fins are symmetrically distributed on the outside of the outer light tube about the middle surface of the light tube; 14-16 wings can be arranged on the same cross-sectional surface. Optionally, the free end connection line of the pin fins is rectangular as a whole, the pin fins include pin fins in mutually perpendicular directions, two short straight wings are arranged along the diameter in one direction, and 12 curved pin fins are arranged in the other direction, 6 are arranged on each side of the 12 curved pin fins and short straight wings, the roots of the curved pin fins are radially connected to the tube wall, the free ends of the curved pin fins are bent in the horizontal direction, along the diameter direction and the chord direction, to ensure that the distance between the free ends of each curved pin fin is the same.

[0062] refer to Figure 7b ,for Figure 7a A three-dimensional diagram of rectangular distributed curved pin fins connected to a convection heat exchange tube. The spacing between each layer of pin fins is 10-30mm, which allows for full and effective heat exchange of the flue gas.

[0063] refer to Figure 8 A group of enhanced heat exchange elements connected with bent pin fins are evenly arranged at the center of the trapezoidal cross section of the convective heat exchange tube bundle 7, which are connected between the lower flat tube sheet of the upper steam drum 3 and the upper flat tube sheet of the lower header 4. The free ends of the bent pin fins can also form an octagonal structure to form a heat exchange tube bundle group. The pin fins are arranged with four straight fins at a direction of 45° to the horizontal radial direction and 45° to the vertical diameter direction. Two bent pin fins are evenly distributed in the 90° angle space between every two straight wings on the same horizontal plane, and are bent to the same side at a certain angle. The free ends of the eight bent pin fins on the same horizontal plane form an octagonal structure. The free ends of the straight fins and the bent pin fins of each tube bundle are embedded with the free ends of the straight fins and the pin fins of the adjacent tube bundles, and the arrangement is compact, thereby improving the convective enhanced heat exchange effect of the enhanced heat exchange elements of the bent pin fins.

[0064] refer to Figure 9aThe boiler shown includes a burner 1, a furnace 2, an upper drum 3, a lower header 4, a membrane water-cooled wall 5, a downcomer 6 and a convection heat exchange tube bundle 7; the burner 1 is arranged in the upper drum 3, and the fuel and air are mixed in the burner 1 and ignited and burned to form a diffusion or premixed flame that fills the furnace space 2; the upper drum 3 and the lower header 4 are cylindrical structures as a whole, and are respectively connected by an upper tube sheet, a lower tube sheet and a cylindrical shell, and the upper and lower ends of the cylindrical shell are respectively connected to the upper tube sheet and the lower tube sheet, and the upper tube sheet of the upper drum 3 and the lower header 4 The upper and lower tube sheets are both provided with a plurality of straight tie rods 14 to support the upper tube sheet and the lower tube sheet to prevent the tube sheets from being deformed and bulged under pressure. The lower header 4 between the upper steam drum 3 is circumferentially connected with a membrane water-cooled wall 5; the cross section of the convection heat exchange tube bundle 7 is a trapezoidal cross-sectional structure from the furnace 2 to the outside, the lower bottom edge of the trapezoid is near the furnace, and the upper bottom edge of the trapezoid is far from the furnace; the convection heat exchange tube bundle 7 is wrapped around a membrane water-cooled wall structure composed of a light tube + flat steel, a group of enhanced heat transfer elements are arranged inside the membrane water-cooled wall structure, and the bottom of the membrane water-cooled wall structure near the furnace is left A flue gas inlet is provided, and a flue gas outlet is reserved at the upper part of the membrane water-cooled wall structure far from the furnace side; the space surrounded by the lower tube sheet of the upper steam drum 1, the upper tube sheet of the lower header 4, the membrane water-cooled wall 5, and the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle 7 close to the flame constitutes a furnace 2 filled with flames; the flue gas burning in the furnace descends from the gap where the flat steel is not provided at the bottom of the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle 7 close to the flame, turns 90 degrees, and flows into the convection heat exchange tube bundle 7; after the flue gas enters the area where the convection heat exchange tube bundle 7 is located, it first horizontally flushes the convection heat exchange tube bundle 7, and then flows into the convection heat exchange tube bundle 7; The bottom of the heat tube bundle 7 is then turned 90 degrees and flows vertically upward to longitudinally flush the outer wall of a group of vertical light tubes of enhanced heat transfer elements arranged in the center of the counter-current heat exchange tube bundle 7, and at the same time horizontally flush the pin fins connected to the outer wall of the vertical light tube to the top and is discharged from the flue gas outlet on the other side; the boiler feed water enters from the upper steam drum 3, enters the lower header 4 through the downcomer 6, and is evenly distributed. The feed water is heated by the membrane water wall 5 and the counter-current heat exchange tube bundle 7 respectively, and is heated into a steam-water mixture, and then flows upward to the upper steam drum 3, and supplies heat to users from the steam outlet 11.

[0065] refer to Figure 9b, is a top view of the enhanced heat exchange element and the boiler it constitutes. A group of enhanced heat transfer elements connected between the lower tube sheet of the upper steam drum 3 and the upper tube sheet of the lower header 4 are evenly arranged at the center of the trapezoidal cross section of the convection heat exchange tube bundle 7. The enhanced heat transfer element is composed of a vertical light tube in the middle and a plurality of radial pin fins arranged outside the vertical light tube. The radial pin fins are connected to a plurality of radial pin fins of the same length evenly distributed along the circumferential cross section at the root on the arc line of the outer wall cross section perpendicular to the center line of the vertical light tube. The free end of each pin fin connected at the root has plastic deformation perpendicular to the cross section of the tube center line, and finally constitutes an enhanced heat exchange component connected with pin fins distributed radially at the root and distributed in a curved and divergent shape at the free end. The top and bottom ends of the vertical light tube retain a set length of the light tube as a flue gas channel. A steam outlet pipe 1 is opened at the external upper header 31 to guide steam into the upper header 3. refer to Fig.10aThe boiler shown includes a furnace 2, an upper drum 3, a lower header 4, a membrane water-cooled wall 5, a downcomer 6 and a convection heat exchange tube bundle 7; the burner 1 is arranged in the upper drum 3, and the gas and air are mixed in the burner and ignited and burned to form a diffusion or premixed flame that fills the furnace space 2; the upper drum 3 and the lower header 4 are cylindrical structures as a whole, and are respectively connected by an upper tube sheet, a lower tube sheet and a cylindrical shell. The upper tube sheet and the lower tube sheet of the upper drum 3 and the lower header 4 are provided with a plurality of straight tie rods 14 to support the upper tube sheet and the lower tube sheet to prevent the tube sheet from being compressed, deformed and bulged. A membrane water-cooled wall 5 is connected circumferentially; a connecting pipe interconnecting the external upper steam drum 31 and the external lower header 41 is provided on the same side of the cylindrical shell of the upper steam drum 3 and the lower header 4; a plurality of vertically staggered arched convection heat exchange tube bundles 7 are arranged between the bottom of the external upper steam drum 3 and the external lower header 4, and the cross-section is a quadrilateral structure, and the number of tube bundles on each external header is 3-4, and the four sides of the quadrilateral are wrapped by a membrane water-cooled wall structure composed of a smooth tube + flat steel; the lower tube sheet of the upper steam drum 3, the upper tube sheet of the lower header 4, the membrane water-cooled wall 5, the external enhanced heat exchange tube bundle ...; the lower tube sheet of the upper steam drum 3, the upper tube sheet of the lower header 4, the membrane water-cooled wall 5 The space surrounded by the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle 7 of the heat element near the furnace body forms a furnace space 2 filled with flames. The smoke burning in the furnace space flows downward toward the external enhanced heat transfer element. At the bottom of the first row of membrane water-cooled wall tubes near the furnace where no flat steel is provided, it turns 90 degrees and flows into the convection heat exchange tube bundle 7 area. After entering the convection heat exchange tube bundle 7, the smoke first flushes the bottom of the convection heat exchange tube bundle 7 horizontally, then turns 90 degrees and flows vertically upward to flush the outer wall surface of a group of vertical light tubes of the enhanced heat transfer element arranged inside the convection heat exchange tube bundle 7. At the same time, the pin fins connected to the outer wall of the vertical light tube are horizontally flushed to the top and discharged from the flue gas outlet on the other side. The boiler feed water enters from the upper steam drum 3, enters the lower header 4 and the external upper steam drum 3 through the downcomer 6 and the connecting pipe for uniform distribution. The feed water is heated by the membrane water-cooled wall 5 and the convection heat exchange tube bundle 7 respectively, and is heated into a steam-water mixture and flows upward to the upper steam drum, and supplies heat to the user from the steam outlet 11. The external enhanced heat transfer element can reduce the cracks and deformation of the tube sheet inside the furnace caused by thermal stress, making the boiler run more safely and effectively extending the service life of the boiler.

[0066] refer to Fig.10b ,for Fig.10a In the top cross-sectional view of the structure described in , the external enhanced heat transfer element surrounds the middle boiler body in a ring shape, and the upper steam drum 3 and the lower header 4 are respectively provided with connecting pipes connecting the external upper steam drum 31 and the external lower header 41.

[0067] refer to Fig.10c ,for Fig.10a In the side cross-sectional view of the structure described in FIG. 1 , the external enhanced heat transfer element surrounds the boiler body in an annular structure. The connecting pipes connect the upper steam drum 3 with the external upper steam drum 31 and the lower header 4 with the external lower header 41 respectively.

[0068] refer to Fig.11 , are some other optional plate-fin and pin-fin structures. A adopts a structure in which plate-fins and pin-fins are staggered on different horizontal planes, and the number of wings on the same horizontal plane should be no less than 12. B adopts a three-staggered plate-fin structure, with a 20° stagger between the upper and lower wings; C adopts a structure in which plate-fins and plate-fins are staggered every 30° to enhance the turbulence of flue gas; D adopts tile-shaped fins, cuts the tube bundle with a smaller diameter in half, connects them to the central tube bundle, and arranges 4-6 tile fins on the same horizontal plane.

[0069] refer to Fig.12 The above-mentioned curved pin fins and plate fins can be divided into a root, a curved section, and a free section, which are labeled L1, L2, and L3 respectively. The size of the root L1 is between 5-15mm, the length of the curved section L2 is 1-1.5 times that of L1, and the length of the free section L3 is 2-4 times that of L1. The tube bundle is divided into long wing and short wing areas, and the length of the short wing is 0.6-0.8 times that of the long wing.

[0070] refer to Fig.13a It is an automatic needle fin bending device. The bending head is placed in the center of two support plates with an arc track in the middle. The front end of the bending head can clamp the needle fin, and the tail can make a circular motion along the arc track of the support plate to bend the needle fin.

[0071] refer to Fig.13b It is a bending head component in the bending device. Several grooves are opened at the front end of the bending head. The grooves are engaged with the pin wings. As the tail moves in a circular arc, the pin wings are pressed down to bend. According to the different bending angles of the pin wings, different groove depths can be set for bending.

[0072] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An enhanced heat transfer element and a fuel gas boiler using the same as a heat exchange component, characterized in that: The invention comprises a burner (1), a furnace (2), an upper drum (3), a lower header (4), a membrane water-cooled wall (5) and a downcomer (6); a convection heat exchange tube bundle (7) is arranged outside the furnace (2), and two ends of the convection heat exchange tube bundle (7) are respectively connected to the upper drum (3) and the lower header (4); the burner (1) is arranged in the upper drum (3), and fuel and air are mixed in the burner and ignited and burned to form a diffusion or premixed flame that fills the furnace space (2); the upper drum (3), the lower header (4) and the membrane water-cooled wall (5) are arranged outside the furnace (2), and the convection heat exchange tube bundle (7) is respectively connected to the upper drum (3) and the lower header (4) at two ends; the burner (1) is arranged in the upper drum (3), and fuel and air are mixed in the burner and ignited and burned to form a diffusion or premixed flame that fills the furnace space (2); the upper drum (3), the lower header (4) and the membrane water-cooled wall (5) are arranged outside the furnace (2), and the convection heat exchange tube bundle (7) is arranged outside the furnace (2), and the two ends of the convection heat exchange tube bundle (7) are respectively connected to the upper drum (3) and the lower header (4) at two ends; the burner (1) is arranged in the upper drum (3), and the fuel and air are mixed in the burner and ignited and burned to form a diffusion or premixed flame that fills the furnace space (2); the upper drum (3), the lower header The box (4) is a cylindrical structure as a whole, and is respectively connected by an upper tube sheet, a lower tube sheet and a cylindrical shell; the upper steam drum (3) and the lower header (4) are circumferentially connected to the membrane water-cooled wall (5); the cross section of the convection heat exchange tube bundle (7) is annular from the furnace to the outside; the space surrounded by the lower tube sheet (12) of the upper steam drum, the upper tube sheet (13) of the lower header, the membrane water-cooled wall (5), and the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle (5) close to the flame constitutes a furnace (2) filled with flames.

2. The enhanced heat transfer element and the oil-fired gas boiler as a heat exchange component according to claim 1, characterized in that: The convection heat exchange tube bundle (7) is arranged symmetrically as a whole; the upper drum (3) and the lower header (4) are annular headers, respectively connected by an annular upper tube sheet, a lower tube sheet and a concentric cylindrical shell with different inner and outer diameters, and the combustion port is arranged at the center of the upper drum (3); the cross section of the convection heat exchange tube bundle (7) is a circular cross section from the furnace to the outside, and the ring line parts on both sides of the circular ring adopt a membrane water-cooled wall structure; the space surrounded by the lower tube sheet of the upper drum (1), the upper tube sheet of the lower header (2), the membrane water-cooled wall (2), and a row of membrane water-cooled wall tubes of the convection heat exchange tube bundle (7) close to the flame constitutes the furnace (2); the flue gas burning in the furnace (2) descends and turns 90 degrees from the bottom flue gas inlet of the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle (7) close to the flame and flows into the convection heat exchange tube bundle (7).

3. The enhanced heat transfer element and the oil-fired gas boiler as a heat exchange component according to claim 1, characterized in that: The convection heat exchange tube bundle (7) comprises a plurality of enhanced heat transfer elements, which are arranged in parallel to form a heat exchange zone. The periphery of the heat exchange zone surrounded by the plurality of enhanced heat transfer elements adopts a membrane water-cooled wall structure. Along the direction in which the smoke enters the heat exchange zone, the cross section of the heat exchange zone gradually decreases or the enhanced heat exchange tubes in the heat exchange zone are arranged symmetrically, with a smoke inlet arranged at the bottom facing the smoke surface and a smoke outlet arranged at the top facing away from the smoke surface. The plurality of enhanced heat exchange tubes adopt enhanced heat transfer elements. The enhanced heat transfer elements include a light tube, and heat exchange fins are arranged on the outer surface of the light tube. The heat exchange fins are a plurality of curved pin fins or plate fins, and a structure in which the pin fins and the plate fins are mutually embedded and staggered on the same horizontal plane, a structure in which the pin fins and the plate fins are mutually staggered on different horizontal planes, a structure in which the plate fins and the plate fins are mutually staggered, or a tile-shaped fin is adopted, and the length of both ends or one end is set to the light tube; the curved pin fin comprises a root, a curved section and a free section, the root is along the normal direction of the light tube surface, and the curved section connects the root and the free section.

4. The enhanced heat transfer element according to claim 3 and the oil-fired gas boiler as a heat exchange component thereof are characterized in that: The outer surface of the light tube is provided with four straight wings along two mutually perpendicular diameter directions, a bent pin wing is arranged between two adjacent straight wings, and the free end of the bent pin wing is bent in the counterclockwise direction or the clockwise direction in the cross section of the light tube.

5. The enhanced heat transfer element according to claim 3 and the oil-fired gas boiler as a heat exchange component thereof are characterized in that: The roots of the bent pin fins are distributed radially, the free ends of the bent pin fins are bent and parallel to each other, and the spacing of the parallel sections is the same; short straight pin fins are also arranged on the outer wall of the light tube, and the short straight pin fins are arranged along the radial direction of the light tube, and the bent pin fins and the short straight pin fins are symmetrically distributed on the outside of the outer light tube about the center plane of the light tube.

6. The enhanced heat transfer element according to claim 3 and the oil-fired gas boiler as a heat exchange component thereof, characterized in that: Four straight wings are arranged along two mutually perpendicular diameter directions on the outer surface of the smooth tube, and a bent pin wing is arranged between two adjacent straight wings. The free ends of the bent pin wing are bent at a set angle toward the straight wing located in the same horizontal plane, and the free ends of the pin wing form a quadrilateral contour in the same horizontal plane; two adjacent rows of enhanced heat exchange tubes can be arranged in series or staggered.

7. The enhanced heat transfer element and the oil-fired gas boiler as a heat exchange component according to claim 1, characterized in that: The upper steam drum (3) and the lower header (4) are cylindrical structures as a whole, and are respectively connected by an upper tube sheet, a lower tube sheet and a cylindrical shell. The upper steam drum (3) and the lower header (4) are circumferentially connected to the membrane water-cooled wall (5); the cross section of the convection heat exchange tube bundle (7) is a trapezoidal cross section from the furnace to the outside; the space surrounded by the lower tube sheet of the upper steam drum (1), the upper tube sheet of the lower header (2), the membrane water-cooled wall (5), and the first row of membrane water-cooled wall tubes of the convection heat exchange tube bundle (5) close to the flame constitutes a furnace (2) filled with flames.

8. The enhanced heat transfer element and the oil-fired gas boiler as a heat exchange component according to claim 1, characterized in that: The convection heat exchange tube bundle (7) is respectively connected to the upper steam drum (3) and the lower header (4) through the external header of the boiler body.

9. The enhanced heat transfer element and the oil-fired gas boiler as a heat exchange component according to claim 1, characterized in that: The external enhanced heat transfer element is annularly arranged around the middle boiler body, and a connecting pipe is provided on the upper steam drum (3) and the lower header (4) to connect the external upper steam drum (31) and the external lower header (41).

10. The enhanced heat transfer element according to claim 1 and the oil-fired gas boiler as a heat exchange component thereof, characterized in that: The upper tube sheet of the upper drum (3) and the lower tube sheet of the lower header (4) are flat tube sheets, ellipsoidal tube sheets or arched tube sheets. When the ellipsoidal tube sheets or arched tube sheets are used, the boiler is used as a land-based oil and gas boiler with a small water level fluctuation. When the ellipsoidal tube sheets are used, the straight tie rods are omitted; when the arched tube sheets are used, the straight tie rods are omitted in the surrounding areas, and the central area is still provided with straight tie rods.

Images