CN111853747A - Cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler - Google Patents
Cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler Download PDFInfo
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- CN111853747A CN111853747A CN202010865686.6A CN202010865686A CN111853747A CN 111853747 A CN111853747 A CN 111853747A CN 202010865686 A CN202010865686 A CN 202010865686A CN 111853747 A CN111853747 A CN 111853747A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B15/00—Water-tube boilers of horizontal type, i.e. the water-tube sets being arranged horizontally
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus
- F22B31/08—Installation of heat-exchange apparatus or of means in boilers for heating air supplied for combustion
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Abstract
The invention discloses a cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler which comprises an upper end enclosure, a shell, a burner distribution head, a water-cooled wall tube bundle, a water-cooled flame tube bundle, a radiation tube bundle, a high-temperature convection tube bundle, a low-temperature convection tube bundle, a descending tube bundle, a lower end enclosure, an external condenser, a premixer, a matched fan, a water feed pump, a gas valve group, a controller and the like. The side surface of the combustor is used for air inlet, and pipes, metal pore plates, ceramic pore plates and the like which are arranged in a close-packed manner are used for preventing backfire and stabilizing flame; the burner is detachably designed, so that the maintenance is convenient; the water-cooled flame tube bundle of the burner distribution head is arranged in a plane or a convex manner, so that the hearth space is utilized to the maximum extent; the water-cooling flame tube bundle on the boiler body is adopted to cool the flame, so that the problem of heat distribution of the water-cooling combustor is solved. The invention realizes the machine-furnace integration of the plane and curved surface burners, has compact structure, realizes low-nitrogen and ultra-low-nitrogen combustion under lower excess air coefficient, and breaks through the technical monopoly of foreign low-nitrogen burner manufacturers in the field of steam boilers.
Description
Technical Field
The invention relates to the technical field of gas boilers, in particular to a cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler.
Background
According to the energy planning of China, the proportion of natural gas in primary energy is increased to more than 15% by 2035 years, and the annual usage amount can reach more than 6400 billion cubic meters. In 2019, the natural gas consumption in China is 3067 billions of cubic meters, and in the next 15 years, the annual natural gas consumption is increased at a high speed. The gas used for industrial fuel in China accounts for about 30% of the total consumption of natural gas, and boilers required in the industrial field are low-pressure small-capacity boilers with the pressure lower than 2.45MPa, including low-pressure hot water boilers and low-pressure steam boilers. At present, coal-fired boilers with the steam volume of less than 35 tons are basically eliminated, and the market of low-pressure small-capacity boilers is monopolized by gas-fired boilers. With the development of industry and the increasing supply of natural gas, the gas low-pressure boiler with less than 35 steam tons will increase at a rate of more than 5% per year in the next 15 years, and the low-pressure gas boiler has bright prospect.
The mainstream pressure-bearing steam boilers in the current market are provided with water pipe type and fire pipe type. The fire tube type boiler comprises a vertical horizontal smoke tube boiler, a horizontal internal combustion wet back boiler (WNS) and the like, and the water tube type boiler comprises a through-flow type boiler, a D-shaped boiler, an angle tube boiler and the like. The matched burners of the main steam boiler are mostly diffusion type burners and cylindrical surface burners, and huge hearth spaces are reserved. In recent years, the technology of a plane/curved surface combustor is rapidly developed, a water-cooled combustor, a porous ceramic plate combustor and a metal fiber/wire mesh combustor have uniform and stable flame, the regulation ratio can reach more than 1:5, the flame temperature is lower than 1100 ℃, the emission of nitrogen oxides is lower than 30mg, the latest environmental protection standard is met, and the burner is widely applied to small gas boilers such as a gas-fired hot water boiler, a gas-fired wall hanging furnace and the like, but does not enter the market of pressure-bearing gas boilers. The plane/curved surface combustor is a surface combustor, flame is suspended in a space 200mm above the panel, huge hearth space is not needed, the combustor can be arranged only by utilizing one furnace wall of the boiler, and therefore a brand new furnace type needs to be designed to match the plane/curved surface combustor. The space of a hearth is reduced, heat exchange is enhanced, heating surfaces at different temperatures are reasonably arranged, and the pressure bearing capacity and the convenience of maintenance of the boiler are ensured, so that a compact and efficient boiler matched with a plane/curved surface combustor needs to be developed.
CN201821004317.2 discloses a low nitrogen stainless steel condensation boiler, furnace from top to bottom arranges, and flame passes through one-level heat exchanger and second grade condensation heat exchanger in proper order, and the combustor that uses is rectangle plane combustor, and the water between the different levels is through the front and back hydroecium intercommunication turn. The boiler is a hot water boiler adaptive to a plane burner, the space of a hearth is small, heat exchange elements are compact, but the boiler has no pressure bearing capacity and cannot generate steam. CN201621007598.8 discloses a low-nitrogen combustion steam boiler, which comprises a furnace chamber, an upper furnace chamber, a lower furnace chamber, and a burner, wherein the furnace chamber includes a water-cooled wall, a first water-cooled tube for reducing flame temperature, a second water-cooled tube for radiation heat exchange, and a third water-cooled tube for convection heat exchange. The inside adopts the staggered light pipe of multirow, and the flue gas side is once the scale deposit then difficult to wash, and the water-cooling tube bundle for cooling flame is easy carbon deposit to block up, also needs regularly to wash, and the furnace body maintenance is inconvenient.
The current market lacks a convenient-to-overhaul pressure-bearing gas boiler with an adaptive plane/curved surface combustor, and a novel vertical water tube boiler is developed for the purpose.
Disclosure of Invention
In order to realize the integration of a plane/curved surface combustor and develop a pressure-bearing natural gas boiler which is convenient to overhaul and maintain and compact in size and realizes low-nitrogen condensation, the invention aims to provide a cylindrical low-nitrogen high-efficiency pressure-bearing water pipe boiler. The middle vertical water pipe comprises five subareas, namely a water-cooled wall pipe bundle, a water-cooled flame pipe bundle, a radiation pipe bundle, a high-temperature convection pipe bundle and a low-temperature convection pipe bundle; the shell is connected with the upper and lower ellipsoidal/spherical end sockets and covers the water wall tube bundle; the heat dissipation loss of the boiler body is reduced; the whole water pipe exchanges heat, the arrangement of the water pipe is optimized along with the change of the smoke temperature, and the average heat exchange coefficient is improved.
In order to achieve the purpose, the following technical scheme is adopted in the patent:
a cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler comprises an upper end enclosure 1, a shell 2, a burner distribution head 3, a membrane water-cooled wall tube bundle 4, a water-cooled flame tube bundle 5, a radiation tube bundle 6, a high-temperature convection tube bundle 7, a low-temperature convection tube bundle 8, a descending tube bundle 9, a lower end enclosure 10, an external condenser 11, a premixer 12, and a matched fan, a feed pump, a gas valve bank and a controller; the membrane wall tube bundle 4, the water-cooled flame tube bundle 5, the radiation tube bundle 6, the high-temperature convection tube bundle 7, the low-temperature convection tube bundle 8 and the downcomer tube bundle 9 are connected between the upper seal head 1 and the lower seal head 10; the membrane wall tube bundle 4 surrounds the radiation tube bundle 6, the high-temperature convection tube bundle 7 and the low-temperature convection tube bundle 8, is connected with the left end tube and the right end tube of the water-cooled flame tube bundle 5 through flat steel, and the membrane wall tube bundle 4, the upper seal head 1 and the lower seal head 10 jointly form a wall surface for restricting the circulation of flue gas; the shell 2 covers the boiler body formed by all the components except the external condenser 11 and the pre-mixer 12, and only exposes the inlet part of the burner distribution head 3 and the connecting part of the boiler body and the external condenser 11; the upper end and the lower end of the membrane type water-cooled wall tube bundle 4, the water-cooled flame tube bundle 5, the radiation tube bundle 6, the high-temperature convection tube bundle 7, the low-temperature convection tube bundle 8 and the falling tube bundle 9 are respectively communicated with the upper end enclosure 1 and the lower end enclosure 10; the outlet of the pre-mixer 12 is communicated with the inlet of a burner distribution head 3, and the burner distribution head 3 is closely adjacent to a water-cooled flame tube bundle 5; the external condenser 11 is connected with an outlet flue of the boiler body, and a pipe side outlet of the external condenser 11 is connected with a water replenishing port of the upper boiler barrel 1; the mixed gas of natural gas and air at the outlet of the premixer 12 firstly enters a combustor distribution head 3, is uniformly distributed from the combustor distribution head 3 to enter a water-cooled flame tube bundle 5, is ignited and combusted on the front surface of the water-cooled flame tube bundle 5, and the generated high-temperature flue gas sequentially passes through a radiation tube bundle 6, a high-temperature convection tube bundle 7 and a low-temperature convection tube bundle 8 and finally enters an external condenser 11; boiler feed water firstly enters the external condenser 11 for tube side preheating, then enters the water replenishing port of the upper seal head 1, is distributed to each tube bundle area through the upper seal head 1, and enters the lower seal head 10; the water in the tube bundle is heated to generate steam, and the steam flows upwards and leaves the boiler from the upper seal head 1; the upper area of the upper seal head 1 is a steam space, the lower area is a water space, and the lower seal head is a water space.
The upper end enclosure 1 and the lower end enclosure 10 are used as pressure-bearing parts, and a spherical end enclosure type and an ellipsoidal end enclosure type are selected; the spherical end socket comprises a spherical end socket, a cylindrical section and a tube plate; the ellipsoidal head comprises an ellipsoidal head, a cylindrical section and a tube plate; the main body structures of the lower end enclosure 10 and the upper end enclosure 1 are the same; the upper seal head 1 is provided with a steam-water separator and a plurality of flange interfaces for water inlet, steam exhaust, maintenance and installation of a pressure gauge, a thermometer, a water level gauge and a safety valve; the lower head 10 is provided with a plurality of flange interfaces for maintenance, pollution discharge and temperature and pressure measurement.
Heat insulation materials are filled between the shell 2 and the membrane wall tube bundle 4, or a cavity is reserved, so that the heat dissipation loss of the boiler body is reduced; the shell 2 is welded with the edges of the tube plates of the upper seal head 1 and the lower seal head 10, plays a role of bracing and is used as a fulcrum line during tube plate strength calculation; a premixed gas inlet, a flue gas outlet, an access hole, a fire observation hole and a measuring point hole are reserved on the shell 2.
The combustor distribution head 3 consists of a premixed gas inlet 3-1, an air shell 3-2, a flow equalizing pore plate 3-4 and a combustion surface 3-5; the combustion surfaces 3-5 adopt a plane or curved surface form and are attached to the water-cooling flame tube bundle 5; the premixed gas inlet 3-1 is parallel to or vertical to the combustion surface 3-5 or forms any angle, the wind shell 3-2 is a divergent section when the premixed gas inlet is parallel to the combustion surface, and the wind shell 3-2 is an isobaric air channel for side air intake when the premixed gas inlet is vertical to the combustion surface; the flow equalizing pore plate 3-4 is positioned between the premixed gas inlet 3-1 in the wind shell 3-2 and the combustion surface 3-5 and is one layer or a plurality of layers, so that the flow of the premixed gas at each position on the combustion surface 3-5 is uniform; the combustion surface 3-5 adopts one of five structures of a metal orifice plate, a porous ceramic plate, rectangular pipes in close arrangement, spiral finned pipes in close arrangement and round pipes in close arrangement; the small holes on the metal pore plate and the porous ceramic plate and the gaps among the densely arranged rectangular tubes, the spiral finned tubes and the circular tubes play roles in preventing backfire, equalizing gas and stabilizing flame; the premixed gas is ignited after the gap of the water-cooled flame tube bundle 5, so that the combustion surfaces 3-5 are not directly impacted by flame, only have a small amount of radiant heat, and are continuously cooled by the room-temperature premixed gas; the close-packed arrangement pipes are directly communicated with the atmosphere, and the gas in the pipes rises after being heated to form natural air circulation cooling close-packed arrangement pipes; cooling the densely arranged pipes by using furnace water; the close-packed arrangement pipe is provided with an upper header 3-5-1 and a lower header 3-5-2, boiler feed water at the outlet of the external flue gas condenser 11 firstly enters the lower header 3-5-2, ascends along the close-packed arrangement pipe to flow to the upper header 3-5-1 and then enters the lower end enclosure 10.
The combustor distribution head 3 also comprises one or more layers of guide plates 3-3 positioned between a premixed gas inlet 3-1 in the air shell 3-2 and a combustion surface 3-5, so that the flow of premixed gas at each position on the combustion surface 3-5 is more uniform;
the burner distribution head 3 is detachable; the burner distribution head 3 is connected and sealed with the water-cooled flame tube bundle 5 in a drawer mode, is placed into the boiler through an opening 2-1 on the shell 2, and is fixed under the constraint of a preset guide rail in the boiler; the frame of the burner distribution head 3 is sealed with the groove surface in the guide rail, and a sealing strip is added to improve the sealing effect; carbon deposition may occur when the burner distribution head is under low load, the detachable burner distribution head 3 is convenient to clean, and long-period safe operation is easier to realize.
The overall arrangement shapes of the membrane wall tube bundle 4, the water-cooled flame tube bundle 5, the radiation tube bundle 6, the high-temperature convection tube bundle 7 and the low-temperature convection tube bundle 8 comprise a rectangle, a trapezoid and a curved edge trapezoid; when rectangular arrangement is adopted, the width of the flue is unchanged; when the trapezoidal arrangement is adopted, the flue at the position of the water-cooling flame tube bundle 5 is widest, and the flue is continuously narrowed along the flowing direction of the flue gas, so that the flow speed of the flue gas is improved; when adopting the trapezoidal arrangement in curved edge, the flue width reduces after increasing earlier, and high temperature convection bank 7 department is widest, and the space of make full use of cylindric shell reduces radiant tube bank 6, high temperature convection bank 7's heat load, reduces intraductal scale deposit risk, reduces the flue width afterwards in order to improve the flue gas velocity of flow, increase coefficient of heat transfer, reduction tube bank use amount.
The burner distribution head 3 and the water-cooled flame tube bundle 5 are arranged in a convex manner to increase the combustion surface area; when the boiler power is increased, the area of a combustor needs to be increased in an equal ratio, the height of the boiler is influenced by transportation and the height limitation of a boiler room, the increase range is limited, the diameters of an end socket and a boiler barrel are limited by the processing capacity and the strength of the barrel, the diameter of the boiler is increased in a limited manner, and at the moment, the combustion surface area is increased and the boiler power is increased under the condition that the width and the height of the boiler are not changed in a convex mode; when the convex arrangement is adopted, the combustion surface is arranged into a trapezoidal, triangular or curved surface with sharp protrusions which goes deep into the hearth space, and the arrangement of the water-cooled flame tube bundle 5 and the radiation tube bundle 6 is changed simultaneously to cool the flame and shield the heat radiation between the combustion surfaces.
The membrane water-cooled wall tube bundle 4 is formed by tangential welding of light tubes with the outer diameter of 25-76 mm or welding of the light tubes and flat steel with the outer diameter of 10-60 mm in an interval arrangement mode or welding of the middle of fin tubes, the tube ends of the upper end socket 1 and the lower end socket 10 are connected through the tangent light tubes to be necked down so as to maintain the minimum required hole bridge size, and an ignition needle, a fire detection needle and a fire observation hole are arranged at the flat steel between the water-cooled flame tube bundle 5 and the membrane water-cooled wall tube bundle 4 and used for igniting premixed gas and detecting and observing flame; the water-cooled flame tube bundle 5 adopts a light tube with the outer diameter of 25-60 mm, the tube bundle interval is 1-20 mm, the height of a wound fin is less than 10mm, and the distance between the surface of the tube bundle and the surface of the burner distribution head 3 is less than 20mm, so that the premixed gas is prevented from catching fire at a gap between the burner distribution head 3 and the water-cooled flame tube bundle 5; the premixed gas leaves the gap of the water-cooled flame tube bundle 5 and then is ignited and combusted, the water-cooled flame tube bundle 5 absorbs the radiant heat of the flame and cools the root of the flame, and therefore the converted nitrogen oxide is lower than 30mg under the condition that the excess air coefficient is less than 1.3; the water-cooled flame tube bundle 5 is washed by high-temperature flame for a long time, condensate water is easily generated on the surface when the furnace is shut down, high-temperature corrosion and low-temperature corrosion need to be prevented, and if stainless steel is adopted, the problem of dissimilar steel welding is faced, so that the corrosion resistance is improved by adopting a mode of spraying nickel-chromium alloy on the surface; the radiant tube bundle 6 adopts a large-diameter tube with the outer diameter of 51-200 mm, the radiant tube bundle region absorbs more than 40% of heat of the boiler, the smoke temperature is higher than 900 ℃, the evaporation is strong, and the large-diameter tube is adopted to avoid flow stagnation caused by steam blockage; the flue gas temperature of the area of the high-temperature convection tube bundle 7 is 900-600 ℃, the heat convection is mainly used, a tube with the outer diameter of 25-76 mm is adopted, a light tube or a finned tube is selected, and the fin height of the finned tube is smaller than 10mm, so that the fins are prevented from being damaged due to overtemperature; the heat exchange temperature difference between the low-temperature convection tube bundle 8 and the external condensation heat exchanger 11 is small, and heat exchange enhancement measures are required to be taken, wherein the measures comprise a dense arrangement light pipe, a spiral finned tube, a finned tube and a pin finned tube; the downcomer 9 is located outside the water-cooled wall tube bundle 4, is not heated between the upper end enclosure 1 and the lower end enclosure 10, is mostly arranged near the water-cooled flame tube bundle 5, the radiation tube bundle 6 and the high-temperature convection tube bundle 7, has large heat flux density in the tube bundle areas and strong water evaporation, a large amount of water needs to be supplemented in the corresponding lower end enclosure 10 area, and the downcomer 9 is arranged to avoid the problem of heat transfer deterioration caused by flow stagnation in the tube bundle areas.
The external condenser 11 is a water pipe type heat exchanger, and heat exchange pipe bundles are all light pipes 11-2, so that the scale on the smoke side is reduced; the water supply quantity of the steam boiler is far less than that of a hot water boiler, in order to ensure that the flow velocity of the water side in the heat exchanger reaches more than 0.3m/s, a plurality of light tubes are divided into a group, and a water chamber 11-3 is adopted to connect the light tubes of each group; the water chamber 11-3 is positioned at two sides of the light pipe 11-2, a partition plate of each upper water pipe and each lower water pipe is arranged in the water chamber, water turns back and flows in each group of pipes, and the water chamber 11-3 is sealed by a flange blind plate 11-4 and can be opened to clean dirt on the water side; the outlet 11-5 is positioned at the upper part of the external condenser 11, so that the water flow can take away the bubbles accumulated in the heat exchanger in time; because the pressure-bearing capacity of the water chamber 11-3 is weaker, the water feeding pump is positioned behind the external condenser 11, and the external condenser 11 is ensured not to bear pressure or only bear slight pressure; the external condenser 11 uses austenitic stainless steel grade 304 or more or ferritic stainless steel grade 430 or more to reduce corrosion of the condensed water.
The premixer 12 provides premixed gas for the burner distribution head 3 and is connected with a premixed gas inlet of the burner distribution head 3; the premixer 12 consists of a cylindrical shell 12-1, a coaxial cylindrical sleeve 12-2, a central air pipe 12-3 and a rectifying plate 12-4; the coaxial cylindrical sleeve 12-2 accounts for 20% -60% of the total axial length of the premixer, and is close to one side of an air inlet of the premixer, so that the premixer is divided into an inner sleeve part and an outer sleeve part, and the areas of the two parts are the same; the central air pipe 12-3 is positioned at the front end of the coaxial cylindrical sleeve 12-2, and the rectifying plate 12-4 is positioned at the outlet side of the premixer 12; the air flows along the axial direction of the premixer 12, the natural gas enters the inner space of a coaxial cylindrical sleeve 12-2 through a cylindrical shell 12-2, the coaxial cylindrical sleeve 12-2 is communicated with a central air pipe 12-3, small holes with inclined axes and surfaces are formed in the inner side and the outer side of the coaxial cylindrical sleeve 12-2 and the lower surface of the central air pipe 12-3, the natural gas is sprayed out from the inclined small holes to form rotary jet flow, so that the gas and the air are fully mixed under the action of rotary stirring, the inner side and the outer side of the coaxial cylindrical sleeve 12-2 are in the same direction or in different directions, and a rectifying plate 12-4 at the outlet side is used for eliminating the rotation of the premixed gas; the rectifying plate 12-4 is a cross plate type, a Chinese character 'mi' plate type or a parallel plate type.
The invention has the advantages and positive effects that:
1. the cylindrical low-nitrogen high-efficiency pressure-bearing water pipe boiler disclosed by the invention adopts a design concept of machine-boiler integration, and the plane/curved surface burner and the pressure-bearing boiler are combined together, so that the structure of a traditional large hearth is abandoned; the full-film type wall cladding reduces the heat dissipation loss of the boiler body; the whole water pipe exchanges heat, the arrangement of the water pipe is optimized along with the change of the smoke temperature, and the average heat exchange coefficient is improved.
2. The plane/curved surface combustor of the cylindrical low-nitrogen high-efficiency pressure-bearing water pipe boiler adopts the water-cooling nitrogen reduction principle, utilizes a part of the heating surface of the boiler body as a water-cooling flame pipe bundle of the combustor, solves the problem of heat distribution of water-cooling low nitrogen, and realizes the aim of discharging nitrogen oxides not higher than 30mg under the condition that the excess air coefficient is less than 1.3.
3. The cylindrical low-nitrogen efficient pressure-bearing water pipe boiler provided by the invention adopts the drawer type detachable burner distribution head, so that the problem that the traditional water-cooling low-nitrogen burner is scrapped due to carbon deposition blockage in long-term operation because the traditional water-cooling low-nitrogen burner cannot be detached is solved.
4. The cylindrical low-nitrogen high-efficiency pressure-bearing water pipe boiler optimizes the arrangement of the combustion plane/curved surface and the radiation pipe bundle, adopts convex arrangement, maximally utilizes the hearth space, and increases the burner power under the given hearth width.
5. The cylindrical low-nitrogen high-efficiency pressure-bearing water pipe boiler provided by the invention adopts the full light pipe condenser, so that the scale formation on the smoke side is reduced, the cleaning is convenient, the water side adopts the water chamber to be connected with each light pipe, and the water chamber can be opened and cleaned, so that the problem that the smoke side and the water side of the traditional condensing heat exchanger are difficult to clean due to scale formation and blockage is solved.
Drawings
FIG. 1 is a schematic cross-sectional view of a cylindrical low-nitrogen energy-saving pressure-bearing water tube boiler according to the present invention.
FIG. 2a is a schematic view of an upper head being ellipsoidal; fig. 2b is a schematic view of the spherical upper end socket.
FIG. 3a is a schematic view of portions of a burner distribution head; FIG. 3b is a schematic view of a drawer type connection; fig. 3c is a schematic view of a cross-sectional view of the burner distribution head.
FIG. 4a is a schematic view of a trapezoidal arrangement of membrane wall tube bundles, water-cooled flame tube bundles, radiant tube bundles, high temperature convection tube bundles, and low temperature convection tube bundles; FIG. 4b is a schematic view of the curved trapezoidal arrangement of the membrane wall tube bundle, the water-cooled flame tube bundle, the radiant tube bundle, the high temperature convection tube bundle and the low temperature convection tube bundle.
FIG. 5 is a schematic diagram of a convex arrangement of a burner distribution head and water-cooled flame tube bundles of a cylindrical low-nitrogen energy-saving pressure-bearing water tube boiler according to the present invention.
FIG. 6 is a schematic view of an external condenser of a cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler according to the present invention.
FIG. 7a is a schematic cross-sectional view of a premixer of a cylindrical low-nitrogen energy-saving pressure-bearing water tube boiler of the present invention; FIG. 7b is a schematic perspective view of a premixer of a cylindrical low-nitrogen energy-saving pressure tube boiler of the present invention.
Detailed Description
The following detailed description of the patent refers to the accompanying drawings and detailed description.
As shown in fig. 1, the cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler comprises an upper end enclosure 1, a shell 2, a burner distribution head 3, a membrane water-cooled wall tube bundle 4, a water-cooled flame tube bundle 5, a radiation tube bundle 6, a high-temperature convection tube bundle 7, a low-temperature convection tube bundle 8, a descending tube bundle 9, a lower end enclosure 10, an external condenser 11, a premixer 12, and a matched fan, a feed pump, a gas valve bank and a controller; the membrane wall tube bundle 4, the water-cooled flame tube bundle 5, the radiation tube bundle 6, the high-temperature convection tube bundle 7, the low-temperature convection tube bundle 8 and the downcomer tube bundle 9 are connected between the upper seal head 1 and the lower seal head 10; the membrane wall tube bundle 4 surrounds the radiation tube bundle 6, the high-temperature convection tube bundle 7 and the low-temperature convection tube bundle 8, is connected with the left end tube and the right end tube of the water-cooled flame tube bundle 5 through flat steel, and the membrane wall tube bundle 4, the upper seal head 1 and the lower seal head 10 jointly form a wall surface for restricting the circulation of flue gas; the shell 2 covers the boiler body formed by all the components except the external condenser 11 and the pre-mixer 12, and only exposes the inlet part of the burner distribution head 3 and the connecting part of the boiler body and the external condenser 11; the upper end and the lower end of the membrane type water-cooled wall tube bundle 4, the water-cooled flame tube bundle 5, the radiation tube bundle 6, the high-temperature convection tube bundle 7, the low-temperature convection tube bundle 8 and the falling tube bundle 9 are respectively communicated with the upper end enclosure 1 and the lower end enclosure 10; the outlet of the pre-mixer 12 is communicated with the inlet of a burner distribution head 3, and the burner distribution head 3 is closely adjacent to a water-cooled flame tube bundle 5; the external condenser 11 is connected with an outlet flue of the boiler body, and a pipe side outlet of the external condenser 11 is connected with a water replenishing port of the upper boiler barrel 1; the mixed gas of natural gas and air at the outlet of the premixer 12 firstly enters a combustor distribution head 3, is uniformly distributed from the combustor distribution head 3 to enter a water-cooled flame tube bundle 5, is ignited and combusted on the front surface of the water-cooled flame tube bundle 5, and the generated high-temperature flue gas sequentially passes through a radiation tube bundle 6, a high-temperature convection tube bundle 7 and a low-temperature convection tube bundle 8 and finally enters an external condenser 11; boiler feed water firstly enters the external condenser 11 for tube side preheating, then enters the water replenishing port of the upper seal head 1, is distributed to each tube bundle area through the upper seal head 1, and enters the lower seal head 10; the water in the tube bundle is heated to generate steam, and the steam flows upwards and leaves the boiler from the upper seal head 1; the upper area of the upper seal head 1 is a steam space, the lower area is a water space, and the lower seal head is a water space.
As a preferred embodiment of the invention, the upper end enclosure 1 and the lower end enclosure 10 are used as pressure-bearing parts, and a spherical end enclosure type and an ellipsoidal end enclosure type are selected; as shown in fig. 2b, the spherical head type comprises a spherical head, a cylindrical section and a tube plate; as shown in fig. 2a, the ellipsoidal head comprises an ellipsoidal head, a cylindrical section and a tube plate; the main body structures of the lower end enclosure 10 and the upper end enclosure 1 are the same; the upper seal head 1 is provided with a steam-water separator and a plurality of flange interfaces for water inlet, steam exhaust, maintenance and installation of a pressure gauge, a thermometer, a water level gauge and a safety valve; the lower head 10 is provided with a plurality of flange interfaces for maintenance, pollution discharge and temperature and pressure measurement.
As a preferred embodiment of the invention, a heat insulating material is filled between the shell 2 and the membrane water wall tube bundle 4, or a cavity is reserved, so that the heat dissipation loss of a boiler body is reduced; the shell 2 is welded with the edges of the tube plates of the upper seal head 1 and the lower seal head 10, plays a role of bracing and is used as a fulcrum line during tube plate strength calculation; a premixed gas inlet, a flue gas outlet, an access hole, a fire observation hole and a measuring point hole are reserved on the shell 2.
As shown in fig. 3a, 3b and 3c, the burner distribution head 3 is composed of four parts, namely a premixed gas inlet 3-1, a wind shell 3-2, a flow equalizing pore plate 3-4 and a combustion surface 3-5; the combustion surfaces 3-5 adopt a plane or curved surface form and are attached to the water-cooling flame tube bundle 5; the premixed gas inlet 3-1 is parallel to or vertical to the combustion surface 3-5 or forms any angle, the wind shell 3-2 is a divergent section when the premixed gas inlet is parallel to the combustion surface, and the wind shell 3-2 is an isobaric air channel for side air intake when the premixed gas inlet is vertical to the combustion surface; the flow equalizing pore plate 3-4 is positioned between the premixed gas inlet 3-1 in the wind shell 3-2 and the combustion surface 3-5 and is one layer or a plurality of layers, so that the flow of the premixed gas at each position on the combustion surface 3-5 is uniform; the combustion surface 3-5 adopts one of five structures of a metal orifice plate, a porous ceramic plate, rectangular pipes in close arrangement, spiral finned pipes in close arrangement and round pipes in close arrangement; the small holes on the metal pore plate and the porous ceramic plate and the gaps among the densely arranged rectangular tubes, the spiral finned tubes and the circular tubes play roles in preventing backfire, equalizing gas and stabilizing flame; the premixed gas is ignited after the gap of the water-cooled flame tube bundle 5, so that the combustion surfaces 3-5 are not directly impacted by flame, only have a small amount of radiant heat, and are continuously cooled by the room-temperature premixed gas; the close-packed arrangement pipes are directly communicated with the atmosphere, and the gas in the pipes rises after being heated to form natural air circulation cooling close-packed arrangement pipes; cooling the densely arranged pipes by using furnace water; the close-packed arrangement pipe is provided with an upper header 3-5-1 and a lower header 3-5-2, boiler feed water at the outlet of the external flue gas condenser 11 firstly enters the lower header 3-5-2, ascends along the close-packed arrangement pipe to flow to the upper header 3-5-1 and then enters the lower end enclosure 10.
As shown in FIG. 3C, the burner distribution head 3 further comprises one or more layers of baffles 3-3 located between the premixed gas inlet 3-1 in the wind shell 3-2 and the combustion surface 3-5, so that the flow rate of the premixed gas at each position on the combustion surface 3-5 is more uniform.
As shown in fig. 3b, the burner distribution head 3 is detachable; the burner distribution head 3 is connected and sealed with the water-cooled flame tube bundle 5 in a drawer mode, is placed into the boiler through an opening 2-1 on the shell 2, and is fixed under the constraint of a preset guide rail in the boiler; the frame of the burner distribution head 3 is sealed with the groove surface in the guide rail, and a sealing strip is added to improve the sealing effect; carbon deposition may occur when the burner distribution head is under low load, the detachable burner distribution head 3 is convenient to clean, and long-period safe operation is easier to realize.
The overall arrangement shapes of the membrane wall tube bundle 4, the water-cooled flame tube bundle 5, the radiation tube bundle 6, the high-temperature convection tube bundle 7 and the low-temperature convection tube bundle 8 comprise a rectangle, a trapezoid and a curved edge trapezoid; when rectangular arrangement is adopted, the width of the flue is unchanged; as shown in fig. 4a, when the water-cooled flame tube bundle 5 is arranged in a trapezoid shape, the flue is widest and is continuously narrowed along the flowing direction of flue gas, so that the flow rate of flue gas is increased; as shown in fig. 4b, when adopting the trapezoidal row in curved edge, the flue width increases earlier and then reduces, and high temperature convection bank 7 department is widest, and the space of make full use of cylindric shell reduces radiant tube bank 6, high temperature convection bank 7's heat load, reduces intraductal scale deposit risk, reduces the flue width afterwards in order to improve the flue gas velocity of flow, increase heat transfer coefficient, reduces the tube bank use amount.
As shown in fig. 5, the burner distribution head 3 and the water-cooled flame tube bundle 5 are arranged in a convex shape to increase the combustion surface area; when the boiler power is increased, the area of a combustor needs to be increased in an equal ratio, the height of the boiler is influenced by transportation and the height limitation of a boiler room, the increase range is limited, the diameters of an end socket and a boiler barrel are limited by the processing capacity and the strength of the barrel, the diameter of the boiler is increased in a limited manner, and at the moment, the combustion surface area is increased and the boiler power is increased under the condition that the width and the height of the boiler are not changed in a convex mode; when the convex arrangement is adopted, the combustion surface is arranged into a trapezoidal, triangular or curved surface with sharp protrusions which goes deep into the hearth space, and the arrangement of the water-cooled flame tube bundle 5 and the radiation tube bundle 6 is changed simultaneously to cool the flame and shield the heat radiation between the combustion surfaces.
As a preferred embodiment of the invention, the membrane wall tube bundle 4 is formed by tangential welding of a light pipe with the outer diameter of 25-76 mm or welding of the light pipe and a flat steel with the diameter of 10-60 mm in an interval arrangement manner or welding the middle of a fin pipe, the pipe ends of the upper end socket 1 and the lower end socket 10 are connected by tangential welding of the light pipe and the flat steel, and the pipe ends are required to be necked down to maintain the minimum required hole bridge size, and an ignition needle, a fire detection needle and a fire observation hole are arranged at the flat steel between the water-cooling flame tube bundle 5 and the membrane wall tube bundle 4 and are used for igniting premixed gas and detecting and observing; the water-cooled flame tube bundle 5 adopts a light tube with the outer diameter of 25-60 mm, the tube bundle interval is 1-20 mm, the height of a wound fin is less than 10mm, and the distance between the surface of the tube bundle and the surface of the burner distribution head 3 is less than 20mm, so that the premixed gas is prevented from catching fire at a gap between the burner distribution head 3 and the water-cooled flame tube bundle 5; the premixed gas leaves the gap of the water-cooled flame tube bundle 5 and then is ignited and combusted, the water-cooled flame tube bundle 5 absorbs the radiant heat of the flame and cools the root of the flame, and therefore the converted nitrogen oxide is lower than 30mg under the condition that the excess air coefficient is less than 1.3; the water-cooled flame tube bundle 5 is washed by high-temperature flame for a long time, condensate water is easily generated on the surface when the furnace is shut down, high-temperature corrosion and low-temperature corrosion need to be prevented, and if stainless steel is adopted, the problem of dissimilar steel welding is faced, so that the corrosion resistance is improved by adopting a mode of spraying nickel-chromium alloy on the surface; the radiant tube bundle 6 adopts a large-diameter tube with the outer diameter of 51-200 mm, the radiant tube bundle region absorbs more than 40% of heat of the boiler, the smoke temperature is higher than 900 ℃, the evaporation is strong, and the large-diameter tube is adopted to avoid flow stagnation caused by steam blockage; the flue gas temperature of the area of the high-temperature convection tube bundle 7 is 900-600 ℃, the heat convection is mainly used, a tube with the outer diameter of 25-76 mm is adopted, a light tube or a finned tube is selected, and the fin height of the finned tube is smaller than 10mm, so that the fins are prevented from being damaged due to overtemperature; the heat exchange temperature difference between the low-temperature convection tube bundle 8 and the external condensation heat exchanger 11 is small, and heat exchange enhancement measures are required to be taken, wherein the measures comprise a dense arrangement light pipe, a spiral finned tube, a finned tube and a pin finned tube; the downcomer 9 is located outside the water-cooled wall tube bundle 4, is not heated between the upper end enclosure 1 and the lower end enclosure 10, is mostly arranged near the water-cooled flame tube bundle 5, the radiation tube bundle 6 and the high-temperature convection tube bundle 7, has large heat flux density in the tube bundle areas and strong water evaporation, a large amount of water needs to be supplemented in the corresponding lower end enclosure 10 area, and the downcomer 9 is arranged to avoid the problem of heat transfer deterioration caused by flow stagnation in the tube bundle areas.
As shown in fig. 6, the external condenser 11 is a water-tube heat exchanger, and the heat exchange tube bundles are all light tubes 11-2, so that the scale on the smoke side is reduced; the water supply quantity of the steam boiler is far less than that of a hot water boiler, in order to ensure that the flow velocity of the water side in the heat exchanger reaches more than 0.3m/s, a plurality of light tubes are divided into a group, and a water chamber 11-3 is adopted to connect the light tubes of each group; the water chamber 11-3 is positioned at two sides of the light pipe 11-2, a partition plate of each upper water pipe and each lower water pipe is arranged in the water chamber, water turns back and flows in each group of pipes, and the water chamber 11-3 is sealed by a flange blind plate 11-4 and can be opened to clean dirt on the water side; the outlet 11-5 is positioned at the upper part of the external condenser 11, so that the water flow can take away the bubbles accumulated in the heat exchanger in time; because the pressure-bearing capacity of the water chamber 11-3 is weaker, the water feeding pump is positioned behind the external condenser 11, and the external condenser 11 is ensured not to bear pressure or only bear slight pressure; the external condenser 11 uses austenitic stainless steel grade 304 or more or ferritic stainless steel grade 430 or more to reduce corrosion of the condensed water.
As shown in fig. 7, the premixer 12 provides the premixed gas to the burner distribution head 3, and is connected to the premixed gas inlet of the burner distribution head 3; the premixer 12 consists of a cylindrical shell 12-1, a coaxial cylindrical sleeve 12-2, a central air pipe 12-3 and a rectifying plate 12-4; the coaxial cylindrical sleeve 12-2 accounts for 20% -60% of the total axial length of the premixer, and is close to one side of an air inlet of the premixer, so that the premixer is divided into an inner sleeve part and an outer sleeve part, and the areas of the two parts are the same; the central air pipe 12-3 is positioned at the front end of the coaxial cylindrical sleeve 12-2, and the rectifying plate 12-4 is positioned at the outlet side of the premixer 12; the air flows along the axial direction of the premixer 12, the natural gas enters the inner space of a coaxial cylindrical sleeve 12-2 through a cylindrical shell 12-2, the coaxial cylindrical sleeve 12-2 is communicated with a central air pipe 12-3, small holes with inclined axes and surfaces are formed in the inner side and the outer side of the coaxial cylindrical sleeve 12-2 and the lower surface of the central air pipe 12-3, the natural gas is sprayed out from the inclined small holes to form rotary jet flow, so that the gas and the air are fully mixed under the action of rotary stirring, the inner side and the outer side of the coaxial cylindrical sleeve 12-2 are in the same direction or in different directions, and a rectifying plate 12-4 at the outlet side is used for eliminating the rotation of the premixed gas; the rectifying plate 12-4 is a cross plate type, a Chinese character 'mi' plate type or a parallel plate type.
Claims (10)
1. The utility model provides a cylindrical low nitrogen energy-conserving pressure-bearing water pipe boiler which characterized in that: the device comprises an upper end enclosure (1), a shell (2), a burner distribution head (3), a membrane water-cooled wall tube bundle (4), a water-cooled flame tube bundle (5), a radiation tube bundle (6), a high-temperature convection tube bundle (7), a low-temperature convection tube bundle (8), a descending tube bundle (9), a lower end enclosure (10), an external condenser (11), a premixer (12) and a matched fan, a feed pump, a gas valve bank and a controller; the membrane type water-cooled wall tube bundle (4), the water-cooled flame tube bundle (5), the radiation tube bundle (6), the high-temperature convection tube bundle (7), the low-temperature convection tube bundle (8) and the downcomer tube bundle (9) are connected between the upper seal head (1) and the lower seal head (10); the membrane type water-cooled wall tube bundle (4) surrounds the radiation tube bundle (6), the high-temperature convection tube bundle (7) and the low-temperature convection tube bundle (8), and is connected with the left end tube and the right end tube of the water-cooled flame tube bundle (5) through flat steel, and the membrane type water-cooled wall tube bundle (4), the upper seal head (1) and the lower seal head (10) jointly form a wall surface for restricting the circulation of flue gas; the shell (2) covers the boiler body formed by all the components except the external condenser (11) and the pre-mixer (12), and only exposes the inlet part of the burner distribution head (3) and the connecting part of the boiler body and the external condenser (11); the upper end and the lower end of the membrane type water-cooled wall tube bundle (4), the water-cooled flame tube bundle (5), the radiation tube bundle (6), the high-temperature convection tube bundle (7), the low-temperature convection tube bundle (8) and the descending tube bundle (9) are respectively communicated with the upper end enclosure (1) and the lower end enclosure (10); the outlet of the premixer (12) is communicated with the inlet of the combustor distribution head (3), and the combustor distribution head (3) is closely adjacent to the water-cooled flame tube bundle (5); the external condenser (11) is connected with an outlet flue of the boiler body, and a pipe side outlet of the external condenser (11) is connected with a water replenishing port of the upper boiler barrel (1); the mixed gas of natural gas and air at the outlet of the premixer (12) firstly enters a combustor distribution head (3), is uniformly distributed from the combustor distribution head (3) and enters a water-cooled flame tube bundle (5), ignition combustion is carried out on the front surface of the water-cooled flame tube bundle (5), and the generated high-temperature flue gas sequentially passes through a radiation tube bundle (6), a high-temperature convection tube bundle (7) and a low-temperature convection tube bundle (8) and finally enters an external condenser (11); boiler feed water firstly enters the pipe side of an external condenser (11) for preheating, then enters a water replenishing port of an upper seal head (1), is distributed to each pipe bundle area through the upper seal head (1), and enters a lower seal head (10); the water in the tube bundle is heated to generate steam, and the steam flows upwards and leaves the boiler from the upper seal head (1); the upper area of the upper seal head (1) is a steam space, the lower area is a water space, and the lower seal head is a water space.
2. The cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler of claim 1, characterized in that: the upper end enclosure (1) and the lower end enclosure (10) are used as pressure-bearing parts, and a spherical end enclosure type and an ellipsoidal end enclosure type are selected; the spherical end socket comprises a spherical end socket, a cylindrical section and a tube plate; the ellipsoidal head comprises an ellipsoidal head, a cylindrical section and a tube plate; the main body structures of the lower end enclosure (10) and the upper end enclosure (1) are the same; the upper end enclosure (1) is provided with a steam-water separator and a plurality of flange interfaces for water inlet, steam exhaust and maintenance, and a pressure gauge, a thermometer, a water level gauge and a safety valve are installed; the lower end enclosure (10) is provided with a plurality of flange interfaces for overhauling, discharging sewage and measuring temperature and pressure.
3. The cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler of claim 1, characterized in that: a heat insulation material is filled between the shell (2) and the membrane wall tube bundle (4), or a cavity is reserved, so that the heat dissipation loss of the boiler body is reduced; the shell (2) is welded with the edges of the tube plates of the upper seal head (1) and the lower seal head (10) to play a role of bracing and serve as a fulcrum line during tube plate strength calculation; a premixed gas inlet, a flue gas outlet, an access hole, a fire observation hole and a measuring point hole are reserved on the shell (2).
4. The cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler of claim 1, characterized in that: the combustor distribution head (3) consists of a premixed gas inlet (3-1), an air shell (3-2), a flow equalizing pore plate (3-4) and a combustion surface (3-5); the combustion surface (3-5) is in a plane or curved surface form and is attached to the water-cooling flame tube bundle (5); the premixed gas inlet (3-1) is parallel to or vertical to the combustion surface (3-5) or forms any angle, the wind shell (3-2) is a divergent section when the premixed gas inlet is parallel to the combustion surface, and the wind shell (3-2) is an isobaric air channel for side air intake when the premixed gas inlet is vertical to the combustion surface; the flow equalizing pore plate (3-4) is positioned between the premixed gas inlet (3-1) in the air shell (3-2) and the combustion surface (3-5) and is one layer or a plurality of layers, so that the flow of the premixed gas at each position on the combustion surface (3-5) is uniform; the combustion surface (3-5) adopts one of five structures of a metal orifice plate, a porous ceramic plate, rectangular pipes in close arrangement, spiral finned pipes in close arrangement and round pipes in close arrangement; the small holes on the metal pore plate and the porous ceramic plate and the gaps among the densely arranged rectangular tubes, the spiral finned tubes and the circular tubes play roles in preventing backfire, equalizing gas and stabilizing flame; the premixed gas is ignited after the gap of the water-cooled flame tube bundle (5), so that the combustion surface (3-5) is not directly impacted by flame, only has a small amount of radiant heat, and is continuously cooled by the room-temperature premixed gas; the close-packed arrangement pipes are directly communicated with the atmosphere, and the gas in the pipes rises after being heated to form natural air circulation cooling close-packed arrangement pipes; cooling the densely arranged pipes by using furnace water; the close-packed arrangement pipe is provided with an upper header (3-5-1) and a lower header (3-5-2), boiler feed water at the outlet of the external flue gas condenser (11) firstly enters the lower header (3-5-2), ascends along the close-packed arrangement pipe to flow to the upper header (3-5-1) and then enters a lower end enclosure (10).
5. The cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler of claim 4, characterized in that: the combustor distribution head (3) also comprises one or more layers of guide plates (3-3) positioned between the premixed gas inlet (3-1) in the air shell (3-2) and the combustion surface (3-5), so that the flow of the premixed gas at each position on the combustion surface (3-5) is more uniform;
the burner distribution head (3) is detachable; the burner distribution head (3) is connected and sealed with the water-cooled flame tube bundle (5) in a drawer mode, is placed into the boiler through an opening (2-1) on the shell (2), and is fixed under the constraint of a preset guide rail in the boiler; the frame of the burner distribution head (3) is sealed with the groove surface in the guide rail, and a sealing strip is added to improve the sealing effect; carbon deposition may occur when the burner distribution head is in low load, the detachable burner distribution head (3) is convenient to clean, and long-period safe operation is easier to realize.
6. The cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler of claim 1, characterized in that: the overall arrangement shapes of the membrane wall tube bundle (4), the water-cooling flame tube bundle (5), the radiation tube bundle (6), the high-temperature convection tube bundle (7) and the low-temperature convection tube bundle (8) comprise a rectangle, a trapezoid and a curved edge trapezoid; when rectangular arrangement is adopted, the width of the flue is unchanged; when the water-cooling flame tube bundle is distributed in a trapezoid manner, the flue at the position of the water-cooling flame tube bundle (5) is widest, and the flue is continuously narrowed along the flowing direction of flue gas, so that the flow speed of the flue gas is improved; when adopting the trapezoidal arrangement in curved edge, the flue width reduces after increasing earlier, and high temperature convection bank (7) department is widest, and the space of make full use of cylindric shell reduces the heat load of radiant tube bank (6), high temperature convection bank (7), reduces intraductal scale deposit risk, reduces the flue width afterwards in order to improve the flue gas velocity of flow, increase coefficient of heat transfer, reduction tube bank use amount.
7. The cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler of claim 1, characterized in that: the burner distribution head (3) and the water-cooled flame tube bundle (5) are arranged in a convex manner to increase the combustion surface area; when the boiler power is increased, the area of a combustor needs to be increased in an equal ratio, the height of the boiler is influenced by transportation and the height limitation of a boiler room, the increase range is limited, the diameters of an end socket and a boiler barrel are limited by the processing capacity and the strength of the barrel, the diameter of the boiler is increased in a limited manner, and at the moment, the combustion surface area is increased and the boiler power is increased under the condition that the width and the height of the boiler are not changed in a convex mode; when the convex arrangement is adopted, the combustion surface is arranged into a trapezoidal, triangular or curved surface with sharp protrusions which penetrates into the hearth space, and the arrangement of the water-cooled flame tube bundle (5) and the radiation tube bundle (6) is changed simultaneously to cool the flame and shield the heat radiation between the combustion surfaces.
8. The cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler of claim 1, characterized in that: the membrane type water-cooled wall tube bundle (4) is formed by welding light tubes with the outer diameter of 25-76 mm in a tangent mode or welding the light tubes and flat steel with the outer diameter of 10-60 mm in an interval mode or welding the middle of fin tubes, the tube ends of the upper end socket (1) and the lower end socket (10) are connected through the tangent mode by the light tubes and should be necked down to maintain the minimum required hole bridge size, and an ignition needle, a fire detection needle and a fire observation hole are arranged at the flat steel position between a water-cooled flame tube bundle (5) and the membrane type water-cooled wall tube bundle (4) and used for igniting premixed gas and detecting and observing flame; the water-cooled flame tube bundle (5) adopts a light pipe with the outer diameter of 25-60 mm, the tube bundle interval is 1-20 mm, spiral fins with the height of the wound fins lower than 10mm are wound, and the distance between the surface of the tube bundle and the surface of the burner distribution head (3) is less than 20mm, so that the premixed gas is prevented from catching fire at a gap between the burner distribution head (3) and the water-cooled flame tube bundle (5); the premixed gas leaves the gap of the water-cooled flame tube bundle (5) and then is ignited and combusted, and the water-cooled flame tube bundle (5) absorbs the radiant heat of flame and cools the root of the flame, so that the converted nitrogen oxide is lower than 30mg under the condition that the excess air coefficient is less than 1.3; the water-cooled flame tube bundle (5) is washed by high-temperature flame for a long time, condensate water is easily generated on the surface during blowing out, high-temperature corrosion and low-temperature corrosion need to be prevented, and if stainless steel is adopted, the problem of dissimilar steel welding is faced, so that the corrosion resistance is improved by adopting a mode of spraying nickel-chromium alloy on the surface; the radiant tube bundle (6) adopts a large-diameter tube with the outer diameter of 51-200 mm, the radiant tube bundle region absorbs more than 40% of heat of the boiler, the smoke temperature is higher than 900 ℃, the evaporation is strong, and the large-diameter tube is adopted to avoid flow stagnation caused by steam blockage; the smoke temperature of the high-temperature convection tube bundle (7) area is 900-600 ℃, the heat convection is mainly used, tubes with the outer diameter of 25-76 mm are adopted, light tubes or finned tubes are selected, and the fin height of the finned tubes is smaller than 10mm, so that the fins are prevented from being damaged due to overtemperature; the heat exchange temperature difference between the low-temperature convection tube bundle (8) and the external condensation heat exchanger (11) is small, and heat exchange enhancement measures including a densely-arranged light tube, a spiral finned tube, a finned tube and a pin finned tube are required; the downcomer bundle (9) is located outside the water-cooled wall tube bundle (4), is not heated between the upper end enclosure (1) and the lower end enclosure (10), is mostly arranged near the water-cooled flame tube bundle (5), the radiation tube bundle (6) and the high-temperature convection tube bundle (7), has large heat flux density in tube bundle areas, strong water evaporation, and a large amount of water needs to be supplemented in the corresponding lower end enclosure (10) area, and the heat transfer deterioration problem caused by flow stagnation in the tube bundle area is avoided by arranging the downcomer bundle (9).
9. The cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler of claim 1, characterized in that: the external condenser (11) is a water pipe type heat exchanger, and heat exchange pipe bundles are all light pipes (11-2), so that the scale on the smoke side is reduced; the water supply quantity of the steam boiler is far less than that of a hot water boiler, in order to ensure that the flow velocity of the water side in the heat exchanger reaches more than 0.3m/s, a plurality of light pipes are divided into a group, and a water chamber (11-3) is adopted to connect each group of light pipes; the water chamber (11-3) is positioned at two sides of the light pipe (11-2), a partition plate of each upper water pipe and each lower water pipe is arranged in the water chamber, water turns back and flows in each group of pipes, and the water chamber (11-3) is sealed by a flange blind plate (11-4) and can be opened to clean dirt on the water side; the outlet (11-5) is positioned at the upper part of the external condenser (11), so that the water flow can take away the bubbles accumulated in the heat exchanger in time; because the pressure-bearing capacity of the water chamber (11-3) is weaker, the water feeding pump is positioned behind the external condenser (11), and the external condenser (11) is ensured not to bear pressure or only bear slight pressure; the external condenser (11) adopts austenitic stainless steel of grade over 304 or ferritic stainless steel of grade over 430 to reduce the corrosion of condensed water.
10. The cylindrical low-nitrogen energy-saving pressure-bearing water pipe boiler of claim 1, characterized in that: the premixer (12) provides premixed gas for the burner distribution head (3) and is connected with a premixed gas inlet of the burner distribution head (3); the premixer (12) consists of a cylindrical shell (12-1), a coaxial cylindrical sleeve (12-2), a central air pipe (12-3) and a rectifying plate (12-4); the coaxial cylindrical sleeve (12-2) accounts for 20% -60% of the total axial length of the premixer, is close to one side of an air inlet of the premixer, and divides the premixer into an inner part of the sleeve and an outer part of the sleeve, and the areas of the two parts are the same; the central air pipe (12-3) is positioned at the front end of the coaxial cylindrical sleeve (12-2), and the rectifying plate (12-4) is positioned at the outlet side of the premixer (12); the air flows along the axial direction of the premixer (12), natural gas enters the inner space of a coaxial cylindrical sleeve (12-2) through a cylindrical shell (12-2), the coaxial cylindrical sleeve (12-2) is communicated with a central air pipe (12-3), the inner side and the outer side of the coaxial cylindrical sleeve (12-2), and the lower surface of the central air pipe (12-3) are provided with small holes with inclined axes and surfaces, the natural gas is sprayed out from the inclined small holes to form rotary jet flow, so that the gas and the air are fully mixed under the action of rotary stirring, the directions of the inner side and the outer side of the coaxial cylindrical sleeve (12-2) are in the same direction or different directions, and a rectifying plate (12-4) at the outlet side is used for eliminating the rotation of premixed gas; the rectifying plate (12-4) is a cross plate type, a Chinese character 'mi' plate type or a parallel plate type.
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| CN113432121A (en) * | 2021-06-09 | 2021-09-24 | 西安交通大学 | Reducing ring rib water-cooling type surface combustion gas device |
| CN113432121B (en) * | 2021-06-09 | 2022-06-21 | 西安交通大学 | Reducing ring rib water-cooling type surface combustion gas device |
| CN113757668A (en) * | 2021-08-09 | 2021-12-07 | 西安交通大学 | Spiral ring rib water-cooling type cold flame gas burner |
| CN118346993A (en) * | 2024-05-22 | 2024-07-16 | 湖北鑫星节能炉具有限公司 | Gas stove core device capable of reducing temperature |
| CN118346993B (en) * | 2024-05-22 | 2024-10-01 | 湖北鑫星节能炉具有限公司 | Gas stove core device capable of reducing temperature |
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