A fully premixed water-cooled combustion water fire tube steam boiler

Abstract

The application discloses a full-premix water-cooled combustion water-fire tube steam boiler, which comprises a flat full-premix water-cooled burner, a water pipe detachable furnace, a smoke pipe boiler body, an air preheater and a condensing economizer. Air and gas mixed by the flat full-premix water-cooled burner are combusted in the furnace space, the generated flue gas is cooled by the water pipe detachable furnace water pipe combination, enters the front and rear through-connected reinforced heat exchange smoke pipe, flows through the smoke pipe boiler body and the air preheater, and is finally collected in the condensing economizer, is folded by 90 degrees upwards and is discharged from a flue gas outlet. Water-cooled combustion reduces the combustion temperature, thereby realizing ultra-low emission of nitrogen oxides; the independent water pipe detachable furnace is high in heat exchange efficiency in the high-temperature zone of flue gas and can rapidly reduce the flue gas temperature, solves the water circulation of water-cooled combustion and is convenient for replacement and maintenance; the smoke pipe boiler body does not contain a furnace and fully adopts in-pipe aluminum fin reinforced heat exchange; the flue gas flow process is fully through-connected from the front to the rear smoke pipe, thereby greatly reducing local resistance of flue gas flow and reducing operation cost.

Description

Technical Field

[0001] This invention relates to the field of gas-fired boiler equipment technology, specifically to a fully premixed water-cooled combustion water-fire tube steam boiler. Background Technology

[0002] In recent years, surface burner technology has developed rapidly, resulting in a variety of forms. Water-cooled burners, porous ceramic plate burners, and metal fiber or wire mesh burners offer a large adjustment ratio, uniform flame, and flame temperatures below 1100℃, suppressing the formation of thermal nitrogen oxides (NOx), with NOx emissions below 30mg, meeting the latest environmental standards. As a type of surface burner, the planar burner only requires one furnace wall for installation. The burner distributor head has a short flame length, hovering only within 200mm behind the combustion plane, thus requiring even less furnace space. Currently, surface burners are mainly used in small-capacity boilers such as gas-fired hot water boilers and gas-fired wall-hung boilers, but have little application in the pressurized gas-fired boiler market.

[0003] In recent years, the rise of new materials, new processes, and emerging combustion technologies, along with market demand for ultra-low nitrogen technology upgrades, has presented significant challenges to flue-tube gas-fired boilers, making transformation and upgrading inevitable. However, breakthroughs in creative technologies to replace traditional structures are still lacking, primarily because:

[0004] In the design and manufacturing of shell-type boilers, to fully absorb the sensible heat in the high-temperature flue gas, a combustion chamber is usually arranged after the furnace shell, and a second or third pass of flue tubes is added. However, the flue tubes are mostly plain or threaded tubes, which, due to the thermal properties of the flue gas, have a relatively small convective heat transfer coefficient, resulting in a low heat flux density on the tube wall. Designers have to resort to conventional methods such as adding more tube passes and increasing the number of flue tubes to reduce the flue gas temperature. However, the second and third pass flue tubes are usually arranged inside the boiler shell, which undoubtedly increases the diameter of the boiler shell and the overall volume of the boiler. At the same time, the flue gas turning also forces an increase in flue gas resistance, increasing the output of the blower and the energy consumption of operation, and reducing the overall operating efficiency of the boiler.

[0005] Traditional two- and three-pass gas-fired boilers are designed to be as compact as possible, minimizing boiler length, boiler shell diameter, and furnace diameter to reduce boiler volume and floor space, while also reducing steel consumption and improving the competitiveness of shell-type gas-fired boilers. However, an excessively small furnace diameter is necessary for achieving ultra-low NOx levels (≤30mg / m³). 3 Technological upgrades often present extreme challenges and fail, primarily because shell-type boilers typically feature cylindrical furnace radiant heating surfaces and generally employ diffusion burners that mix gas and air. Local combustion temperatures can reach 1900℃, making ultra-low NOx levels (≤30mg / m³) extremely difficult to achieve. 3This requires the addition of a tail-end flue gas recirculation (FGR) system, which causes numerous problems such as decreased combustion efficiency, condensate corrosion, and increased boiler resistance. This is especially troublesome for users who have already completed the technical upgrade.

[0006] A series of flue tube boiler products that choose internal fins to enhance heat exchange inside the flue tube all face a problem: the internal aluminum fins cannot directly contact the high-temperature flue gas generated by combustion. In order to prevent overheating, the aluminum fins inside a section of the flue tube near the furnace are often removed, and heat exchange is carried out by the bare tube alone. The heat exchange cannot be fully and effectively enhanced, and the overall heat exchange area is increased.

[0007] The existing flue gas boilers have a relatively primitive design, lacking modular and integrated design concepts and aesthetic appeal. They do not pay attention to the rationality of the layout and the coordination between modules, resulting in unreasonable planning between auxiliary modules. The original flue gas boilers on the market did not consider deep condensation of flue gas to recover a large amount of latent heat from the condensate in the flue gas. In the later design and operation process, in order to reduce the investment in modification and redesign and development, air preheaters and condensing heat exchangers were directly added to the top of the boiler, forming a "backpack-style" structure, which affects the aesthetics, increases the flow resistance of flue gas, and does not truly guarantee the condensation efficiency of water vapor in the flue gas. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems existing in the current gas-fired boiler technology and provide a fully premixed water-cooled combustion water-fire tube steam boiler, which reduces the length of the combustion flame, lowers the combustion temperature and the emission of pollutants such as NOx, reduces the steel consumption in boiler manufacturing, reduces the flow resistance of boiler flue gas and thus reduces the power consumption of the fan, and ultimately reduces the carbon emissions of boiler manufacturing and operation.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a fully premixed water-cooled combustion water-tube steam boiler, comprising a flat-plate fully premixed water-cooled burner, a detachable water-tube furnace, a flue-tube boiler body, an air preheater, and a condensing economizer. The flat-plate fully premixed water-cooled burner is located at the front end of the detachable water-tube furnace, and a water-cooled combustion tube bank is located at the front end of the detachable water-tube furnace. The flue-tube boiler body, air preheater, and condensing economizer are sequentially arranged at the rear end of the detachable water-tube furnace along the flue gas flow direction. The flue-tube boiler body, air preheater, and condensing economizer all adopt a shell-and-tube structure. The flue-tube boiler body and condensing economizer are provided with internally finned heat exchange flue tubes, and the air preheater is provided with internally and externally conjugate heat exchange flue tubes. The air outlet of the air preheater is connected to the air inlet of the flat-plate fully premixed water-cooled burner.

[0010] The detachable water-tube furnace includes two vertically arranged downcomers. The downcomers are connected to four horizontal corner tubes to form a corner tube frame structure. The detachable water-tube furnace is connected to the boiler body through the four horizontal corner tubes. The horizontal corner tubes are divided into two groups, left and right. The horizontal corner tubes on the same side are arranged with side wall water-cooled walls parallel to the downcomers. The horizontal corner tubes are divided into two groups, upper and lower, which are connected to the upper and lower headers arranged horizontally. A row of water-cooled combustion tubes and a row of slotted heat exchange tubes are arranged vertically between the upper and lower headers. The water-cooled combustion tubes, the row of slotted heat exchange tubes, and the side wall water-cooled walls surround and form the furnace space.

[0011] The boiler body consists of a boiler shell, a front tube sheet, a rear tube sheet, and several rectangularly arranged internally finned heat exchange flue tubes. The boiler shell, front tube sheet, rear tube sheet, and several rectangularly arranged internally finned heat exchange flue tubes enclose the boiler water space. Four connecting pipes are arranged around the boiler shell near the front tube sheet. The upper two pipes are horizontally arranged non-radial pipes, with their axes aligned with the steam-water interface of the detachable water-tube furnace and the boiler body. The lower two pipes are arranged radially along the boiler shell and connected to the detachable water-tube furnace. A feedwater inlet is located near the front end of the boiler shell, and a steam outlet is located near the rear end. The boiler body is connected to the front flange of the air preheater via a flange located on the rear tube sheet.

[0012] The air preheater includes an air preheater shell, inside which are arranged conjugate enhanced heat exchange flue tubes with the same layout as the flue tube boiler body. On one side of the air preheater shell, an air inlet is arranged horizontally and side by side near the rear end and an air outlet is arranged near the front end. The air outlet is connected to the air inlet of the flat-plate fully premixed water-cooled burner through a flue. The air preheater is connected to the connecting flange of the condenser economizer through the rear flange.

[0013] The condensing economizer includes a condensing economizer shell, a condensing economizer front tube sheet, and a condensing economizer rear tube sheet. The condensing economizer shell contains internally finned heat exchange flue tubes arranged in the same manner as the flue-tube boiler body. The condensing economizer shell, the condensing economizer front tube sheet, and the condensing economizer rear tube sheet enclose a shell-side water space, in which baffles are installed. A hot water outlet is located at the front end of the condensing economizer shell and is connected to the feed water inlet via a pipe, while a cold water inlet is located at the rear end. A condensing economizer flue gas outlet is located at the top of the flue gas collection point at the rear end of the condensing economizer shell, and a condensate drain outlet is located at the bottom.

[0014] The flat-plate fully premixed water-cooled burner includes a premixer, a distributor, a burner head anti-backfire structure, and a water-cooled combustion tube bank. The premixer has a premixer air inlet, a premixer gas inlet, and a premixer outlet. The premixer outlet, distributor, burner head anti-backfire structure, and water-cooled combustion tube bank are arranged along the medium flow direction. After the air and gas enter the premixer, they are mixed evenly to form a premixed gas. The premixed gas flows into the distributor from the premixer outlet along the premixer axis. The distributor has a distributor circular inlet and a distributor square outlet. The premixer outlet, the distributor circular inlet, the distributor square outlet, the burner head anti-backfire structure inlet, and the burner head anti-backfire structure outlet are all connected to the water-cooled combustion tube bank through detachable flanges.

[0015] The distributor's circular inlet and square outlet face the same or opposite directions, allowing the premixer to be positioned in front of the burner head or on any of its sides.

[0016] In the detachable water pipe furnace, a flue gas outlet is set on the slotted heat exchange tube bank, and the flue gas outlet is close to the front tube plate of the boiler body; the four horizontal corner tubes are connected to the boiler body by direct welding or flanges; the flue gas outlet is surrounded by four channel steels filled with refractory material.

[0017] In the area enclosed by the flue gas outlet, the slotted heat exchange tube bank adopts a structure in which several symmetrical arc-shaped finned tubes and bare tubes are arranged alternately. In the area outside the flue gas outlet, the tube bank uses bare tubes, and flat steel is welded between the bare tubes to form a water-cooled wall structure. The symmetrical arc-shaped finned tubes and bare tubes are arranged alternately. Two arc-shaped fins are symmetrically welded on the left and right sides of the circular tube in the symmetrical arc-shaped finned tube. The arc-shaped fins are made by cutting the tube with a diameter larger than that of the circular tube, and the fin length near the furnace space is smaller than the fin length near the flue gas outlet. The arc-shaped fins of two adjacent symmetrical arc-shaped finned tubes symmetrically surround a bare circular tube to form a slotted flue gas flow channel.

[0018] The internally finned heat exchange flue tube adopts a steel-aluminum composite process, which tightly connects the first steel tube with the first internal aluminum fins; the internally and externally conjugate heat exchange flue tube also adopts a steel-aluminum composite process, which tightly connects the second steel tube with the second internal aluminum fins, and spiral fins are arranged on the outside of the steel tube.

[0019] The internally finned enhanced heat exchange flue and the internally and externally conjugate enhanced heat exchange flue are connected by shortening the internal aluminum fins on one side and lengthening the internal aluminum fins on the other side through a steel-aluminum composite process.

[0020] The inner-finned enhanced heat exchange flue in the condenser economizer is kept horizontal before the front tube sheet of the condenser economizer. The inner-finned enhanced heat exchange flue is connected to the inner and outer conjugate enhanced heat exchange flue of the air preheater. The inner-finned enhanced heat exchange flue is inclined downward at a set angle between the front tube sheet and the rear tube sheet of the condenser economizer.

[0021] The detachable water pipe furnace adopts two or three sets of upper and lower headers, with two or three rows of slotted heat exchange tubes arranged between the upper and lower headers; the furnace space is formed by the convex water-cooled combustion tubes, the row of slotted heat exchange tubes away from the burner and the side wall water-cooled wall.

[0022] The detachable water-pipe furnace adopts a SZS-like structure, including an upper drum, a lower drum, a convex water-cooled combustion tube bank, and several rows of slotted heat exchange tube banks. The convex water-cooled combustion tube bank and several rows of staggered slotted heat exchange tube banks are connected between the upper drum and the lower drum, forming the furnace space together with the side water-cooled wall.

[0023] The boiler body front tube plate adopts an arch shape. The front end of the arched boiler body front tube plate extends 80-120mm beyond the front end of the boiler shell, and a circular groove is vertically cut in the extended part to form a comb-shaped slot that tightly connects with the water pipe row at the tail of the detachable furnace.

[0024] An explosion-proof door is installed on the water-cooled wall section above the slotted heat exchange tube bank.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] 1. The flat-plate fully premixed water-cooled burner used in the boiler of this invention features a versatile distributor structure that allows for flexible adjustment of the premixer and the fan position connected to its air inlet, saving space. The distributor's orderly arrangement of the premixed gas, combined with the burner head's anti-backfire structure, effectively prevents accidents such as deflagration, flameout, and backfire during burner ignition. The burner, including the premixer, distributor, and burner head, is connected by detachable flanges, facilitating maintenance and cleaning. Damaged parts can be directly replaced. The design allows for detachable connections of the burner and water pipes in the furnace, addressing the issues of easy clogging in fully premixed burners and easy ash accumulation and corrosion on the furnace heating surfaces and flue pipes. This facilitates cleaning and maintenance of the burner, furnace, and flue pipes, as well as the repair and replacement of damaged parts, improving boiler operational stability and extending boiler service life.

[0027] 2. The available detachable water tube furnace structure and flue tube boiler body structure are varied. The detachable water tube furnace can adopt a corner tube frame structure or a SZS-like boiler body structure. Depending on the desired furnace outlet flue gas temperature or flue gas inlet temperature, the number of heated tubes in the detachable water tube furnace can be increased or decreased. Depending on the different detachable water tube furnace structures, a flat tube sheet flue tube boiler body or an arched front tube sheet flue tube boiler body can be selected.

[0028] 3. The boiler adopts a water-tube furnace combined with a flue-tube boiler body. The water-cooled combustion tubes in the water-tube furnace serve as the water-cooled heating surface of the water-cooled fully premixed burner, solving the water circulation problem of the water-cooled burner. At the same time, the water-tube furnace provides flue gas at a temperature of about 750°C, which allows for the full use of high-efficiency internal finned heat exchange flue tubes in the flue-tube boiler body, improving the overall heat exchange coefficient of the boiler, reducing the heat exchange area, thereby reducing manufacturing costs and reducing the volume of the boiler body.

[0029] Furthermore, this invention leverages the similar structural steel-aluminum composite reinforced heat exchange flue tubes used in the boiler body, air preheater, and condensing economizer. It creatively employs a connection method that shortens the inner fins of the preceding flue tubes and lengthens the inner fins of the following tubes, using a steel-aluminum composite process to connect the preceding and following tubes. This connection method avoids the abrupt expansion and contraction of the flow area when flue gas passes between the boiler body, air preheater, and condensing economizer, effectively reducing local resistance on the flue gas side. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the main structure of a fully premixed water-cooled combustion water-tube steam boiler that is feasible according to the present invention.

[0031] Figure 2 This is a schematic diagram of a feasible flat-plate fully premixed water-cooled burner according to the present invention.

[0032] Figure 3a This is a schematic diagram of a feasible premixer side-mounted burner structure according to the present invention.

[0033] Figure 3b This is a schematic diagram of a feasible premixer bottom burner structure according to the present invention.

[0034] Figure 4 This is a schematic diagram of a feasible angle-tube type detachable furnace structure according to the present invention.

[0035] Figure 5 This is a schematic diagram of the structure of the heat exchange tube bank with detachable water pipes and furnace gap reinforcement in this invention.

[0036] Figure 6 This is a schematic diagram of the main body structure of a furnaceless flue gas tube boiler that can be implemented according to the present invention.

[0037] Figure 7 This is a schematic diagram of the air preheater structure in this invention.

[0038] Figure 8 This is a schematic diagram of the condenser energy-saving device in this invention.

[0039] Figure 9 This is a schematic diagram of the structure of the connection between the enhanced heat exchange flue and the inner and outer conjugate enhanced heat exchange flue in this invention.

[0040] Figure 10 This is a schematic diagram of another feasible seamless reinforced multi-heat exchange tube corner tube detachable furnace structure in this invention.

[0041] Figure 11 This is a schematic diagram of another implementable SZS type detachable water pipe furnace structure in this invention.

[0042] Figure 12 This is a schematic diagram of another feasible arched tube sheet flue gas boiler body structure according to the present invention.

[0043] In the attached diagram, 1-flat plate-type fully premixed water-cooled burner, 11-premixer, 111-premixer air inlet, 112-premixer gas inlet, 113-premixer outlet, 12-distributor, 121-distributor circular inlet, 122-distributor square outlet, 13-burner head anti-backfire structure, 131-burner head anti-backfire structure inlet, 132-burner head anti-backfire structure outlet, 2-water-tube detachable furnace, 21-downcomer, 22-horizontal angle tube, 23-side wall water-cooled wall, 24-header, 241-upper drum, 242-lower drum, 25-water-cooled combustion tube bank, 26-slot-enhanced heat exchange tube bank, 27-furnace space, 28-flue gas outlet, 3-smoke tube boiler body, 31-boiler shell, 32-boiler body front tube plate, 33-boiler... Furnace body rear tube sheet, 34-connecting pipe, 35-feedwater inlet, 36-steam outlet, 4-air preheater, 41-air preheater shell, 42-air outlet, 43-air inlet, 44-front flange, 45-rear flange, 5-condenser economizer, 51-condenser economizer shell, 52-condenser economizer front tube sheet, 53-condenser economizer rear tube sheet, 54-cold water inlet, 55-baffle plate, 56-hot water outlet, 57-condenser economizer flue gas outlet, 58-condensate outlet, 6-symmetrical arc-shaped finned tube, 61-arc-fin, 7-inner fin enhanced heat exchange flue tube, 71-first steel tube, 72-first internal aluminum fin, 8-inner and outer conjugate enhanced heat exchange flue tube, 81-second steel tube, 82-second internal aluminum fin, 83-spiral fin. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings.

[0045] The terms "front," "rear," "left," and "right" used in this invention refer to the relative positions of the boiler body. The burner is located in the front, and the condensing energy-saving device is located in the rear. Facing the front of the boiler, the boiler has a left side and a right side.

[0046] refer to Figure 1 and Figure 2The present invention provides a fully premixed water-cooled combustion water-tube steam boiler, including a flat-plate fully premixed water-cooled burner 1, a detachable water-tube furnace 2, a flue-tube boiler body 3, an air preheater 4, and a condensing economizer 5. The flat-plate fully premixed water-cooled burner 1 is arranged at the front end of the detachable water-tube furnace 2 and forms a water-cooled combustion head with the water-cooled combustion tube row 25. The flue-tube boiler body 3, the air preheater 4, and the condensing economizer 5 are arranged sequentially along the flue gas flow direction at the rear end of the detachable water-tube furnace 2.

[0047] The boiler body 3, air preheater 4, and condenser 5 all adopt a shell-and-tube structure. The boiler body 3 and condenser 5 are equipped with internally finned heat exchange flue tubes 7, and the air preheater 4 is equipped with internally and externally conjugate heat exchange flue tubes 8. The air outlet of the air preheater 4 is connected to the premixer air inlet 111 of the flat-plate fully premixed water-cooled burner 1.

[0048] The detachable water-pipe furnace 2 includes two vertically arranged downcomer pipes 21. The downcomer pipes 21 are connected vertically to four horizontal corner pipes 22 to form a corner pipe frame structure. The detachable water-pipe furnace 2 is connected to the boiler body connecting pipe 34 through the four horizontal corner pipes 22. The horizontal corner pipes 22 are divided into two groups, left and right. The horizontal corner pipes 22 on the same side are arranged with side wall water-cooled walls 23 parallel to the downcomer pipes. The horizontal corner pipes 22 are divided into two groups, upper and lower, and are respectively connected to the horizontally arranged upper and lower headers 24. A water-cooled combustion pipe row 25 and a slotted heat exchanger pipe row 26 are vertically arranged between the upper and lower headers 24. The water-cooled combustion pipe row 25, the slotted heat exchanger pipe row 26 and the side wall water-cooled walls 23 surround and form the furnace space 27.

[0049] refer to Figure 2 , Figure 3a , Figure 3bThe flat-plate fully premixed water-cooled burner 1 includes a premixer 11, a distributor 12, a burner head backfire prevention structure 13, and a water-cooled combustion tube array 25. The premixer 11 is provided with a premixer air inlet 111, a premixer gas inlet 112, and a premixer outlet 113. The premixer outlet, distributor 12, burner head backfire prevention structure 13, and water-cooled combustion tube array 25 are arranged along the medium flow direction. After the air and gas enter the premixer, they are mixed evenly to become premixed gas. The premixed gas flows from the premixer outlet 113 into the distributor 12 along the axis of the premixer 11. The distributor 12 is provided with a distributor circular inlet 121 and a distributor square outlet. 122, the circular inlet 121 of the distributor organizes the flow inside the distributor and finally distributes it to the square outlet 122 of the distributor, flowing orderly into the burner head anti-backfire structure 13; the burner head anti-backfire structure 13 is provided with a burner head anti-backfire structure inlet 131 and a burner head anti-backfire structure outlet 132, and the burner head anti-backfire structure 13 cooperates with the water-cooled combustion tube bank 25 to form a water-cooled combustion head; the premixer outlet 113 and the circular inlet 121, the square outlet 122 and the burner head anti-backfire structure inlet 131, the burner head anti-backfire structure outlet 132 are all connected to the water-cooled combustion tube bank 25 through detachable flanges.

[0050] As an optional embodiment, the distributor circular inlet 121 and distributor square outlet 122 of the distributor 12 of the present invention can face the same direction or face opposite directions. The relative positions of the distributor circular inlet 121 and distributor square outlet 122 can be flexibly changed so that the premixer 11 can be located on the front side of the combustion head and on any side of the burner head.

[0051] refer to Figure 2 and Figure 4 The detachable water-pipe furnace 2 employs a corner tube frame structure consisting of two vertically arranged downcomer tubes 21 connected vertically to four horizontal corner tubes 22. The horizontal corner tubes 22 are divided into left and right groups. On the same side, water-cooled walls 23 are arranged parallel to the downcomer tubes between the horizontal corner tubes 22. The horizontal corner tubes 22 are also connected to horizontally arranged upper and lower headers 24. Between the upper and lower headers, a row of water-cooled combustion tubes 25 and a row of convex slotted heat exchange tubes 26 are vertically arranged. The water-cooled combustion tubes 25, slotted heat exchange tubes 26, and side wall water-cooled walls 23 enclose and form the furnace space 27. The detachable water-pipe furnace 2 is connected to the boiler body connecting pipe 34 via the four horizontal corner tubes 22. The two independent, unheated downcomer tubes 21 in the corner tube frame structure serve as water pipes, and the internal natural circulation of the detachable water-pipe furnace 2 provides sufficient circulation power.

[0052] refer to Figure 6The boiler body 3 is formed by a boiler shell 31, a front tube plate 32, a rear tube plate 33, and several rectangular internally finned heat exchange flue tubes 7, which enclose the boiler water space, excluding the furnace space. Four connecting pipes 34 are arranged around the boiler shell 31 near the front tube plate 32, of which the upper two are non-radial pipes arranged horizontally, and their axes are highly consistent with the steam-water interface of the detachable water-pipe furnace 2 and the boiler body 3. A feedwater inlet 35 is set near the front end of the top of the boiler shell 31, and a steam outlet 36 is set near the rear end. The boiler body 3 is connected to the front flange 44 of the air preheater 4 through a flange set on the rear tube plate 33 of the boiler body.

[0053] refer to Figure 7 The air preheater 4 is constructed by arranging conjugate enhanced heat exchange flue tubes 8 inside the air preheater shell 41 in the same manner as the flue tube boiler body 3. The air preheater shell 41 has an air inlet 43 near the rear end and an air outlet 42 near the front end arranged horizontally on one side. The air outlet 42 is connected to the air inlet of the flat-plate fully premixed water-cooled burner 1 through the flue. The air preheater 4 is connected to the connecting flange of the condenser economizer 5 through the rear flange 45.

[0054] refer to Figure 8 The condenser economizer 5 adopts the same arrangement as the boiler body 3, with the internally finned heat exchange flue tubes 7, the condenser economizer shell 51, the condenser economizer front tube plate 52, and the condenser economizer rear tube plate 53 forming a shell-side water space. A baffle plate 55 is set inside the shell-side water space. The front end of the condenser economizer shell 51 is provided with a hot water outlet 56, which is connected to the feed water inlet 35 through a pipe, and the rear end is provided with a cold water inlet 54. The top of the flue gas collection point at the tail end of the condenser economizer shell 51 is provided with a condenser economizer flue gas outlet 57, and the bottom is provided with a condensate outlet 58. The condensate generated by the flue gas cooling through this part is collected here and discharged from the condensate outlet 58.

[0055] In the fully premixed water-cooled combustion water-tube steam boiler provided by the present invention, cold air enters from the air inlet 43 of the air preheater 4, turns 180° inside the air preheater shell 41, and simultaneously sweeps across the outer spiral fins 83 of the inner and outer conjugate enhanced heat exchange flue tubes 8 to exchange heat with the flue gas inside the tubes. Then, it flows out of the air preheater 4 from the air outlet 42, and the hot air flows into the air inlet of the flat-plate fully premixed water-cooled burner 1 through the pipeline. Natural gas flows into the premixer gas inlet 112 of the flat-plate fully premixed water-cooled burner 1 and mixes evenly with hot air. It is then evenly distributed across the entire combustion plane and ignited in the water-cooled combustion tube bank 25 of the detachable water-pipe furnace 2 for fully premixed water-cooled combustion. A portion of the heat from the generated flue gas at approximately 1100°C is absorbed by the side wall water-cooled wall 23 and then flows backward through the gaps in the slotted enhanced heat exchange tube bank 26 for enhanced heat exchange. The temperature drops to approximately 750°C and flows through the flue gas outlet 28 into the inner finned enhanced heat exchange tube 7 of the flue gas boiler body 3. The flue gas flows through the inner finned enhanced heat exchange tube 7 and the inner and outer conjugate enhanced heat exchange tube 8, which are connected front and rear, and passes through the flue gas boiler body 3, air preheater 4, and condenser economizer 5, where it is continuously cooled. Finally, it is discharged from the top through the flue gas outlet 57 of the condenser economizer.

[0056] The water-side process of a fully premixed water-cooled combustion water-tube steam boiler provided by this invention is as follows: Cold water enters from the cold water inlet 54 in the condenser economizer 5, and undergoes several 180° turns under the guidance of the baffle plate 55, absorbing heat from the flue gas inside the inner-finned enhanced heat exchange flue tube 7. Then, it flows out from the hot water outlet 56 and enters the feedwater inlet 35 of the boiler body 3 via a connecting pipe. Inside the boiler shell 31, part of the water absorbs heat from the flue gas inside the inner-finned enhanced heat exchange flue tube 7 to generate steam, which is directly discharged from the boiler body through the steam outlet 36. The other part of the water flows into the detachable water-tube furnace 2 through the connecting pipe 34 for independent natural circulation, absorbing radiation and convection heat from the high-temperature flue gas to generate steam, which then flows into the boiler body 3 through the upper horizontal angle tube 22 and finally exits from the boiler body 3 through the steam outlet 36. During boiler operation, the steam-water interface remains on the plane where the two axes of the upper horizontal angle tube 22 coexist.

[0057] refer to Figure 4 and Figure 6 In the detachable water pipe furnace 2, a flue gas outlet 28 is set behind the slotted heat exchange tube bank 26, which is surrounded by four channel steels filled with refractory material and forms a seal with the front tube plate 32 of the boiler body. The four horizontal corner pipes 22 are connected to the boiler body connecting pipe 34 by direct welding or flange. When necessary, the detachable water pipe furnace 2 can be completely removed for maintenance or replaced as a whole.

[0058] refer to Figure 5The slotted heat exchange tube bank 26 is composed of several symmetrical arc-shaped finned tubes 6 and plain tubes arranged alternately. Two arc-shaped fins 61 are symmetrically welded on the left and right sides of the circular tube in the symmetrical arc-shaped finned tubes 6. The arc-shaped fins 61 are made by cutting a circular tube with a diameter slightly larger than that of the circular tube along the axial direction. The length of the arc-shaped fins on the side closer to the furnace space 27 is shorter than the length of the arc-shaped fins on the side closer to the flue gas outlet 28 to prevent the arc-shaped fins on the side closer to the furnace from overheating. The arc-shaped fins of two adjacent symmetrical arc-shaped finned tubes 6 symmetrically surround a plain circular tube to form a slotted flue gas flow channel. The tube bank outside the rectangle formed by the flue gas outlet 28 of the slotted heat exchange tube bank 26 is made of plain tubes, and flat steel is welded between the plain tubes to form a water-cooled wall structure. An explosion-proof door is installed in the water-cooled wall section above the slotted heat exchange tube bank 26 to ensure the safety of combustion in the furnace.

[0059] refer to Figure 7 and Figure 9 The internally finned enhanced heat exchange flue tube 7 employs a steel-aluminum composite process, tightly bonding the first steel tube 71 with the first internal aluminum fins 72. The first internal aluminum fins 72 consist of three centrally symmetrical extruded aluminum fin units with identical shapes and structures. The aluminum fin axes of each unit remain parallel, and one fin on one side edge has a bend at a set angle to eliminate the high-temperature zone of flue gas that may appear at the fin root where the fin units connect, thereby enhancing heat exchange. The internally and externally conjugate enhanced heat exchange flue tube 8 also employs a steel-aluminum composite process, tightly bonding the second steel tube 81 with the second internal aluminum fins 82, but with spiral fins 83 arranged on the outside of the steel tube to enhance heat exchange on the air side outside the tube.

[0060] The inner finned heat exchange flue tube 7 of the flue tube boiler body 3 is located at the front end of the front tube plate 32 of the boiler body. When the flue gas temperature at the tail end of the detachable water pipe furnace 2 is higher than 650℃, the first internal aluminum fin 72 is subjected to conical cutting treatment to prevent the fin tip at the flue tube inlet from overheating.

[0061] refer to Figure 9The internally finned heat exchange flue 7 and the internally and externally conjugate heat exchange flue 8 employ a method where one side of the internal aluminum fins is shortened and the other side is lengthened. For example, the first steel pipe 71 of the internally finned heat exchange flue 7 is shortened compared to the first internal aluminum fin 72, while the second steel pipe 81 of the internally and externally conjugate heat exchange flue 8 is lengthened compared to the second internal aluminum fin 82, and then connected using a steel-aluminum composite process. If it is necessary to control the flue gas velocity inside the pipe in the air preheater and condenser economizer according to the heat exchange situation, the structure of the internal aluminum finned tube can be modified to change the flue gas flow area. Alternatively, the steel pipe can be necked or expanded near the connection point of the two flue pipes. The first internal aluminum fin 72 is an extruded aluminum fin. The internally finned heat exchange flue 7 can be a self-vibrating internally inserted bent fin composite flue 7; the first steel pipe and its internal structure of the internally and externally conjugate heat exchange flue 8 can also be a self-vibrating internally inserted bent fin composite flue 7. The inner and outer conjugate enhanced heat exchange flue 8 can also adopt a coaxial conjugate opposite enhanced heat exchange tubular element; the inner finned enhanced heat exchange flue 7 can also adopt the steel pipe and internal structure of the coaxial conjugate opposite enhanced heat exchange tubular element.

[0062] Preferably, the internally finned enhanced heat exchange flue 7 used in the condenser economizer 5 is kept horizontal before the front tube plate 52 of the condenser economizer and connected to the inner and outer conjugate enhanced heat exchange flue 8 of the air preheater 4. The internally finned enhanced heat exchange flue 7 is inclined downward at a set angle between the front tube plate 52 and the rear tube plate 53 of the condenser economizer to ensure that the condensate from the flue gas in the tube can be discharged smoothly.

[0063] refer to Figure 10 As an optional embodiment, the detachable water-pipe furnace 2 adopts two to three sets of upper and lower headers 24, and a row of water-cooled combustion tubes 25 or two to three rows of staggered slotted heat exchange tubes 26 are arranged between the upper and lower headers 24; the convex water-cooled combustion tubes 25, the first row of slotted heat exchange tubes 26 and the left and right side water-cooled walls 23 surround to form the furnace space 27; the convex water-cooled combustion tubes 25 are connected to the flange of the flat-plate fully premixed water-cooled burner, and thick-walled tubes with a wall thickness of about 5mm are required to ensure strength.

[0064] refer to Figure 11 The detachable water pipe furnace 2 adopts a similar SZS structure. A convex water-cooled combustion tube bank 25 and several rows of staggered slotted heat exchange tube banks 26 are connected between the upper boiler drum 241 and the lower boiler drum 242. Together with the side wall water-cooled wall 23, they form a furnace space 27. The convex water-cooled combustion tube bank 25 is connected to the flange of the flat-plate fully premixed water-cooled burner. Thick-walled tubes with a wall thickness of about 5mm are required to ensure strength.

[0065] refer to Figure 12The boiler body front tube plate 32 is arched, with its front end extending 80-120mm beyond the front end of the boiler shell 31. A vertically cut circular groove forms a comb-shaped slot on the extended portion of the boiler body 32, which tightly connects to the water pipe array at the rear of the detachable water pipe furnace 2. With this structure, the 750℃ flue gas from the detachable water pipe furnace 2 is further cooled as it passes through the arched tube plate. Therefore, the first internal aluminum fin 72 of the internally finned heat exchange flue pipe 7, connected to the rear end of the arched boiler body front tube plate 32, has no risk of overheating and requires no cutting.

Claims

1. A fully premixed water-cooled combustion water-tube steam boiler, characterized in that, The system includes a flat-plate fully premixed water-cooled burner (1), a detachable water-tube furnace (2), a flue-tube boiler body (3), an air preheater (4), and a condensing economizer (5). The flat-plate fully premixed water-cooled burner (1) is located at the front end of the detachable water-tube furnace (2). A water-cooled combustion tube bank (25) is located at the front end of the detachable water-tube furnace (2). The flue-tube boiler body (3), the air preheater (4), and the condensing economizer (5) are arranged sequentially along the flue gas flow direction at the rear end of the detachable water-tube furnace (2). The flue-tube boiler body (3), the air preheater (4), and the condensing economizer (5) all adopt a shell-and-tube structure. The flue-tube boiler body (3) and the condensing economizer (5) are equipped with internally finned enhanced heat exchange flue tubes (7). The air preheater (4) is equipped with internally and externally conjugate enhanced heat exchange flue tubes (8). The air outlet of the air preheater (4) is connected to the air inlet of the flat-plate fully premixed water-cooled burner (1). The detachable water-pipe furnace (2) includes two vertically arranged downcomers (21). The downcomers (21) are connected vertically to four horizontal corner pipes (22) to form a corner pipe frame structure. The detachable water-pipe furnace (2) is connected to the boiler body connecting pipe (34) through the four horizontal corner pipes (22). The horizontal corner pipes (22) are divided into two groups, left and right. The horizontal corner pipes (22) on the same side are arranged with side wall water-cooled walls (23) parallel to the downcomers. The horizontal corner pipes (22) are divided into two groups, upper and lower, and are respectively connected to the horizontally arranged upper and lower headers (24). A row of water-cooled combustion tubes (25) and a slotted heat exchange tube row (26) are vertically arranged between the upper and lower headers (24). The water-cooled combustion tubes (25), the slotted heat exchange tube row (26) and the side wall water-cooled walls (23) surround the furnace. The furnace space (27) is formed; in the area enclosed by the flue gas outlet (28) on the slotted heat exchange tube bank (26), a structure is adopted in which several symmetrical arc-shaped finned tubes (6) are arranged alternately with bare tubes. In the area outside the flue gas outlet (28), the tube bank is made of bare tubes, and flat steel is welded between the bare tubes to form a water-cooled wall structure; the symmetrical arc-shaped finned tubes (6) are arranged alternately with bare tubes; two arc-shaped fins (61) are symmetrically welded on the left and right sides of the round tube in the symmetrical arc-shaped finned tube (6). The arc-shaped fins (61) are made by cutting the tube with a diameter larger than that of the round tube, and the fin length near the furnace space (27) is smaller than that near the flue gas outlet (28); the arc-shaped fins of two adjacent symmetrical arc-shaped finned tubes (6) symmetrically surround a bare round tube to form a slotted flue gas flow channel.

2. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, The boiler body (3) includes a boiler shell (31), a boiler body front tube sheet (32), a boiler body rear tube sheet (33), and several rectangularly arranged internally finned heat exchange flue tubes (7). The boiler shell (31), boiler body front tube sheet (32), boiler body rear tube sheet (33), and several rectangularly arranged internally finned heat exchange flue tubes (7) form a boiler water space. The boiler shell (31) has four connecting pipes (34) arranged around the boiler body front tube sheet (32), of which the upper two are made of... The non-radial tubes are arranged horizontally, and their axis is aligned with the steam-water interface of the detachable water pipe furnace (2) and the flue gas boiler body (3). The two lower tubes are arranged radially along the boiler shell (31) and connected to the detachable water pipe furnace (2). The top of the boiler shell (31) is provided with a water inlet (35) near the front end and a steam outlet (36) near the rear end. The flue gas boiler body (3) is connected to the front flange (44) of the air preheater (4) through a flange provided on the rear tube plate (33) of the boiler body.

3. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, The air preheater (4) includes an air preheater shell (41). The air preheater shell (41) is equipped with internal and external conjugate enhanced heat exchange flue tubes (8) arranged in the same manner as the flue tube boiler body (3). The air preheater shell (41) is horizontally arranged with an air inlet (43) near the rear end and an air outlet (42) near the front end on one side. The air outlet (42) is connected to the air inlet of the flat-plate fully premixed water-cooled burner (1) through the flue. The air preheater (4) is connected to the connecting flange of the condenser energy saver (5) through the rear flange (45).

4. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, The condenser (5) includes a condenser shell (51), a condenser front tube sheet (52) and a condenser rear tube sheet (53). The condenser shell (51) is equipped with internally finned heat exchange flue tubes (7) arranged in the same manner as the flue tube boiler body (3). The condenser shell (51), the condenser front tube sheet (52) and the condenser rear tube sheet (53) form a shell-side water space. A baffle plate (55) is installed in the shell-side water space. A hot water outlet (56) is provided at the front end of the condenser shell (51) and is connected to the feed water inlet (35) through a pipe. A cold water inlet (54) is provided at the rear end. A condenser flue gas outlet (57) is provided at the top of the flue gas collection point at the tail end of the condenser shell (51), and a condensate drain outlet (58) is provided at the bottom.

5. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, The flat-plate fully premixed water-cooled burner (1) includes a premixer (11), a distributor (12), a burner head anti-backfire structure (13), and a water-cooled combustion tube bank (25). The premixer (11) is provided with a premixer air inlet (111), a premixer gas inlet (112), and a premixer outlet (113). The premixer outlet, distributor (12), burner head anti-backfire structure (13), and water-cooled combustion tube bank (25) are arranged along the medium flow direction. After the air and gas enter the premixer, they are mixed evenly to form a... The premixed gas flows from the premixer outlet (113) into the distributor (12) along the axis of the premixer (11); the distributor (12) is provided with a circular inlet (121) and a square outlet (122); the premixer outlet (113), the circular inlet (121), the square outlet (122), the burner head anti-backfire structure inlet (131), and the burner head anti-backfire structure outlet (132) are all connected to the water-cooled combustion pipe row (25) through detachable flanges.

6. The flat-plate fully premixed water-cooled burner according to claim 5, characterized in that, The distributor (12) has a circular inlet (121) and a square outlet (122) facing the same direction or opposite directions, so that the premixer (11) is arranged on the front side of the burner head and on any side above, below, left, or right.

7. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, In the detachable water pipe furnace (2), a flue gas outlet (28) is provided on the slotted heat exchange tube bank (26), and the flue gas outlet (28) is close to the front tube plate (32) of the boiler body; the four horizontal corner tubes (22) are connected to the boiler body connecting pipe (34) by direct welding or flange; the flue gas outlet (28) is surrounded by four channel steels filled with refractory material.

8. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, The inner finned heat exchange flue (7) adopts a steel-aluminum composite process to tightly connect the first steel pipe (71) with the first internal aluminum fin (72); the inner and outer conjugate heat exchange flue (8) also adopts a steel-aluminum composite process to tightly combine the second steel pipe (81) with the second internal aluminum fin (82), and arranges spiral fins (83) on the outside of the steel pipe.

9. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, The internal finned heat exchange flue (7) and the internal and external conjugate heat exchange flue (8) are connected by shortening the internal aluminum fins on one side and lengthening the internal aluminum fins on the other side, and then using a steel-aluminum composite process.

10. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, The inner finned heat exchange flue (7) in the condenser economizer (5) is kept horizontal in front of the front tube plate (52) of the condenser economizer. The inner finned heat exchange flue (7) is connected to the inner and outer conjugate heat exchange flue (8) of the air preheater (4). The inner finned heat exchange flue (7) is tilted downward at a set angle between the front tube plate (52) and the rear tube plate (53) of the condenser economizer.

11. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, The detachable water pipe furnace (2) adopts two or three sets of upper and lower headers (24), and two or three rows of slotted heat exchange tubes (26) are arranged between the upper and lower headers (24); the convex water-cooled combustion tubes (25), a row of slotted heat exchange tubes (26) away from the burner and the side wall water-cooled wall (23) surround to form the furnace space (27).

12. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, The detachable water pipe furnace (2) adopts a SZS-like structure, including an upper boiler drum (241), a lower boiler drum (242), a convex water-cooled combustion tube bank (25), and several rows of slotted heat exchange tube banks (26). The convex water-cooled combustion tube bank (25) and several rows of slotted heat exchange tube banks (26) are connected between the upper boiler drum (241) and the lower boiler drum (242), forming a furnace space (27) with the side wall water-cooled wall (23).

13. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, The front tube plate (32) of the boiler body is arched. The front end of the arched front tube plate (32) extends 80~120mm beyond the front end of the boiler shell (31), and a circular groove is vertically cut in the extended part to form a comb-shaped slot that is tightly connected to the tail water pipe of the detachable furnace (2).

14. The fully premixed water-cooled combustion water-tube steam boiler according to claim 1, characterized in that, An explosion-proof door is installed on the water-cooled wall section above the slotted heat exchange tube bank (26).

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