Dual-fuel steam boiler combusting biomass and natural gas

Abstract

The invention discloses a biomass and natural gas fired dual-fuel steam boiler, and relates to the technical field of steam boilers, the biomass and natural gas fired dual-fuel steam boiler comprises a heating structure, a backdraft structure and a boiler barrel, a front smoke box is fixedly mounted on one side of the boiler barrel, a side cover is fixedly mounted on one side of the boiler barrel, a rear smoke box is fixedly mounted on one side of the side cover, and a support is clamped to the bottom of the boiler barrel; a water feeding pump is fixedly installed on one side of the boiler barrel, and a liquid level device is clamped to the outer surface of the boiler barrel. According to the dual-fuel steam boiler combusting the biomass and the natural gas, through matched arrangement of a heating structure, a backdraft structure and a liquid level device, the device can better conduct sufficient combustion during use, the boiler furnace is accurately clamped to the middle of the front pipe plate and the middle of the combustion chamber pipe plate, and an efficient heat transfer path is built through matching of a second return stroke pipe and a third return stroke pipe; after fuel is fully combusted in the combustion chamber to release heat energy, smoke carries heat to orderly flow in the return stroke pipes, full heat exchange with media in the boiler barrel is achieved, and heat is extracted to the maximum degree to be used for generating steam.

Description

Technical Field

[0001] The invention relates to the technical field of steam boilers, in particular to a dual-fuel steam boiler burning biomass and natural gas. Background Art

[0002] In today's industrial production field, steam, as a key heat energy carrier, is widely used in many industries such as chemical industry, food processing, textile printing and dyeing, papermaking, etc. It is used in core production links such as material heating, drying, and cooking. Its stable supply and efficient output are of great significance to the control of enterprise production capacity and product quality. Traditional steam boilers mostly rely on a single fuel, and the common ones are coal-fired boilers, oil-fired boilers, and pure natural gas boilers or biomass-fired boilers. With the increasingly stringent environmental protection requirements and the diversified changes in the energy structure, the disadvantages of these traditional single-fuel boilers are gradually emerging. On the one hand, although coal is used as fuel alone, it has dominated the market due to its low cost and abundant reserves, but the combustion emits a large amount of pollutants such as smoke, sulfur dioxide, and nitrogen oxides, causing serious environmental problems such as haze and acid rain, and has been gradually restricted and eliminated in various places. Oil-fired boilers have high operating costs, frequent oil price fluctuations, and fuel combustion is also accompanied by considerable pollutant generation, which is not in line with the trend of green and low-carbon development. On the other hand, single-fired natural gas boilers are highly dependent on the natural gas supply pipeline network. In remote areas with imperfect pipeline coverage or in winter, gas is used. Peaks are facing a gas shortage dilemma, with limited security. Biomass-fired boilers are significantly affected by the seasonal and regional supply of biomass raw materials. It is difficult to collect and store raw materials, and the transportation radius is short. Supply interruptions often occur, causing production to stagnate. In view of the limitations of single-fuel boilers, dual-fuel technology of biomass and natural gas has emerged, aiming to integrate the advantages of the two and complement their shortcomings. Biomass fuel is renewable and has relatively stable costs. The use of agricultural and forestry waste is in line with the concept of circular economy. Natural gas is clean, easy to regulate combustion, and has strong supply stability. However, the current development of dual-fuel boilers still faces the dilemma of technical adaptation. Some products are simply a combination of biomass and natural gas combustion systems, and the collaborative working mechanism between the two has not been deeply optimized. When switching fuels, the combustion conditions fluctuate violently, and the combustion efficiency is greatly reduced. In terms of structural integration, the integration of heating, smoke exhaust, steam-water circulation and other links is rigid, the sealing between components is poor, and thermal stress is concentrated, resulting in frequent failures such as leakage and deformation, which is difficult to meet the long-term, stable and efficient steam use demands of the industry. Innovative design is urgently needed to break through technical barriers and develop dual-fuel steam boilers with excellent comprehensive performance.

[0003] However, the existing devices have the following problems:

[0004] The existing technology has low combustion efficiency in actual use. Most conventional boilers have simple structural designs, and the combustion space layout is not optimized. It is difficult for the fuel to burn fully and evenly in the furnace. In particular, biomass fuel has complex characteristics, uneven composition, and large fluctuations in calorific value. If the combustion is not well organized, local lack of oxygen and flameout or incomplete combustion may easily occur. A large amount of unburned material is discharged with the flue gas, and the heat loss increases dramatically. The traditional single-return or double-return flue design makes the heat exchange between the flue gas and the medium in the boiler drum hasty and insufficient, and a large amount of waste heat is discharged into the atmosphere without being utilized. The overall thermal efficiency hovers at a low level, and energy consumption remains high, which increases the operating costs of the enterprise and wastes energy resources. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the shortcomings of the prior art, the present invention provides a dual-fuel steam boiler burning biomass and natural gas, which has the advantages of stability and efficient combustion, and solves the problems of the prior art in actual use, such as low combustion efficiency, simple structural design of most conventional boilers, poor optimization of combustion space layout, and difficulty in fully and evenly burning fuel in the furnace. In particular, biomass fuel has complex characteristics, uneven composition, and large fluctuations in calorific value. If the combustion is not well organized, local lack of oxygen, flameout or incomplete combustion may easily occur, and a large amount of unburned material is discharged with the flue gas, resulting in a sharp increase in heat loss. The traditional single-return or double-return flue design makes the heat exchange between the flue gas and the medium in the boiler drum hasty and insufficient, and a large amount of waste heat is discharged into the atmosphere without being utilized. The overall thermal efficiency hovers at a low level, and the energy consumption remains high, which increases the operating costs of the enterprise and wastes energy resources.

[0007] (II) Technical solution

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a dual-fuel steam boiler burning biomass and natural gas, comprising a heating structure, a backfire structure and a boiler drum, a front smoke box is fixedly installed on one side of the boiler drum, a side cover is fixedly installed on one side of the boiler drum, a rear smoke box is fixedly installed on one side of the side cover, a bracket is clamped on the bottom of the boiler drum, a water feed pump is fixedly installed on one side of the boiler drum, and a liquid level meter is clamped on the outer surface of the boiler drum.

[0009] Preferably, the heating structure includes a furnace core, a front tube plate, a combustion chamber tube plate, a second return pipe, and a third return pipe. The furnace core is clamped in the middle of the front tube plate and the combustion chamber tube plate, and the front tube plate and the combustion chamber tube plate are connected through the second return pipe.

[0010] Preferably, the backdraft structure includes a backdraft chamber, a fire viewing plate, and a fire viewing hole, and one side of the backdraft structure is connected to the combustion chamber tube plate of the heating structure.

[0011] Preferably, a lifting lug is fixedly installed on the top of the boiler drum, a safety valve pipe is fixedly installed on the top of the boiler drum, and a steam valve pipe is fixedly installed on the top of the boiler drum.

[0012] Preferably, an instrument tube is fixedly mounted on the top of the front smoke box, and a flame injection port is opened in the middle of the front smoke box.

[0013] Preferably, a connecting hole is opened in the middle of the side cover, a through hole is opened in the middle of the side cover, the connecting hole is clamped with one side of the third return pipe of the heating structure, and the through hole is clamped with the fire viewing hole of the backburning structure.

[0014] Preferably, a drain valve is fixedly installed on one side of the rear smoke box, and an economizer is fixedly installed on the top of the rear smoke box.

[0015] Preferably, a water inlet pipe is fixedly installed on the top of the water pump, and a delivery pipeline is fixedly installed on one side of the water pump.

[0016] Preferably, a display meter is clamped on the bottom of the liquid level device, and a water delivery device is clamped on the bottom of the display meter.

[0017] (III) Beneficial effects

[0018] Compared with the prior art, the present invention provides a dual-fuel steam boiler burning biomass and natural gas, which has the following beneficial effects:

[0019] This dual-fuel steam boiler that burns biomass and natural gas can achieve better and more complete combustion when in use through the coordinated setting of the heating structure, the backfire structure and the liquid level device. The furnace core is accurately connected to the middle of the front tube plate and the combustion chamber tube plate, and the second and third return pipes are matched to build an efficient heat transfer path. After the fuel is fully burned in the combustion chamber to release heat energy, the flue gas carries heat and circulates in each return pipe in an orderly manner, achieving sufficient heat exchange with the medium in the drum, extracting heat to the greatest extent for steam generation, reducing heat loss and waste, and improving thermal efficiency. The liquid level device accurately controls the water level in real time, the bottom connection display table intuitively presents the water level data, the water delivery device flexibly adjusts the water volume, and the top water inlet pipe of the coordinated water pump ensures water supply. The one side delivery pipeline stably delivers water to ensure the constant water level of the drum, eliminating the risk of explosion caused by dry burning. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of a dual-fuel steam boiler burning biomass and natural gas proposed by the present invention;

[0021] Figure 2 This is a schematic diagram of the explosion structure of a dual-fuel steam boiler burning biomass and natural gas proposed by the present invention;

[0022] Figure 3 This is a schematic diagram of the structure of a feed water pump for a dual-fuel steam boiler burning biomass and natural gas proposed by the present invention;

[0023] Figure 4 This is a schematic diagram of the side cover structure of a dual-fuel steam boiler burning biomass and natural gas proposed by the present invention;

[0024] Figure 5 This is a schematic diagram of the instrument tube structure of a dual-fuel steam boiler burning biomass and natural gas proposed by the present invention;

[0025] Figure 6 This is a schematic diagram of the structure of a dual-fuel steam boiler economizer that burns biomass and natural gas proposed by the present invention;

[0026] Figure 7 A dual-fuel steam boiler burning biomass and natural gas is proposed in the present invention Figure 2 Enlarged structural diagram at A in the middle.

[0027] In the figure: 1. Heating structure; 2. Boiler drum; 3. Backdraft structure; 4. Front smoke box; 5. Side cover; 6. Rear smoke box; 7. Bracket; 8. Water feed pump; 9. Liquid level gauge; 10. Lifting lug; 11. Safety valve pipe; 12. Steam valve pipe; 13. Instrument pipe; 14. Flame inlet; 15. Connecting hole; 16. Penetration hole; 17. Drain valve; 18. Economizer; 19. Water inlet pipe; 20. Delivery pipeline; 21. Display meter; 22. Water delivery device. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1-7, heating structure 1, backfire structure 3 and boiler drum 2, a front smoke box 4 is fixedly installed on one side of the boiler drum 2, the heating structure 1 includes a furnace 101, a front tube plate 102, a combustion chamber tube plate 103, a second return pipe 104, and a third return pipe 105, the furnace 101 is clamped in the middle of the front tube plate 102 and the combustion chamber tube plate 103, the front tube plate 102 and the combustion chamber tube plate 103 are connected through the second return pipe 105, the backfire structure 3 includes a backfire chamber 301, a fire viewing plate 302, and a fire viewing hole 303, one side of the backfire structure 3 is connected to the combustion chamber tube plate 103 of the heating structure 1, a lifting ear 10 is fixedly installed on the top of the boiler drum 2, a safety valve pipe 11 is fixedly installed on the top of the boiler drum 2, a steam valve pipe 12 is fixedly installed on the top of the boiler drum 2, and the front smoke box 4 An instrument tube 13 is fixedly installed on the top, a flame inlet 14 is provided in the middle of the front smoke box 4, a side cover 5 is fixedly installed on one side of the drum 2, a connecting hole 15 is provided in the middle of the side cover 5, a penetration hole 16 is provided in the middle of the side cover 5, the connecting hole 15 is clamped with one side of the third return pipe 105 of the heating structure 1, and the penetration hole 16 is clamped with the fire viewing hole 303 of the backfire structure 3, so that the furnace 101 of the heating structure 1 is precisely clamped with the middle of the front tube plate 102 and the combustion chamber tube plate 103, the furnace 101 serves as the core space for fuel combustion, and provides a stable place for biomass or natural gas combustion, the front tube plate 102 and the combustion chamber tube plate 103 are firmly connected by means of the second return pipe 104, so as to construct a closed and efficient heat conduction path, and the fuel is fully burned in the combustion chamber. After releasing heat energy, the flue gas carries heat and flows through the second return pipe 104 and the third return pipe 105 in turn, circulates in each return pipe in an orderly manner, realizes sufficient heat exchange with the medium such as water in the drum 2, and extracts heat to the maximum extent for generating steam. One side of the reburning chamber 301 of the reburning structure 3 is tightly connected with the combustion chamber tube plate 103 of the heating structure 1. Some incompletely burned fuel and flue gas can enter the reburning chamber 301 for secondary combustion and sufficient heat release, further improving the combustion efficiency and heat utilization rate. The liquid level gauge 9 is clamped on the outer surface of the drum 2, and the display meter 21 and the water delivery device 22 are clamped on the bottom of the liquid level gauge 9. The display meter 21 presents the water level height in the drum 2 in real time in the form of intuitive numbers or liquid level gauges, so that the operator can grasp the water level status at a glance. The water delivery device 22 can be connected according to the water level gauge 9. The water level threshold is set to automatically or manually adjust the water volume. The water supply pump 8 is installed on one side of the boiler drum 2. The water inlet pipe 19 on the top is connected to the external water source to ensure sufficient supply water. The delivery pipe 20 on one side is connected to the boiler drum 2 to pump water into the boiler drum 2. The liquid level meter 9 and other components are coordinated to ensure that the water level of the boiler drum 2 is constant in a safe and efficient operation range to eliminate the risk of dry burning. On one side of the boiler drum 2, the front smoke box 4 is fitted to the side of the boiler drum 2 according to the designed position and is evenly tightened with high-strength bolts to ensure the sealing of the connection. An instrument pipe 13 is installed on the top of the front smoke box 4. The instrument pipe 13 is connected to the key monitoring points inside the boiler. It can collect parameters such as flue gas temperature and pressure in real time and transmit them to the external monitoring system to provide data basis for operation and control. The flame inlet 14 opened in the middle,As the key passage for the combustion flame of biomass or natural gas to enter the internal heat exchange area of ​​the boiler, the side cover 5 is first installed on the other side of the drum 2. The side cover 5 is precisely connected with one side of the third return pipe 105 of the heating structure 1 by means of the connection hole 15 on its own structure to ensure that the return pipe is stable and sealed. The side cover 5 is installed with the rear smoke box 6. The drain valve 17 on one side of the rear smoke box 6 is used to regularly drain the condensed water accumulated inside to prevent corrosion and blockage. The economizer 18 is installed on the top. The economizer 18 recovers the waste heat of the flue gas and preheats the feed water entering the boiler to improve energy utilization;

[0030] See also Figure 2 , a bracket 7 is clamped at the bottom of the drum 2. First, according to the overall size and weight requirements of the boiler, a solid foundation is built at the predetermined installation site to ensure that it can bear various loads during the operation of the boiler. The bracket 7 is accurately placed on the foundation and firmly fixed by bolts or welding. The bracket 7 serves as the supporting skeleton of the entire boiler, providing a stable and horizontal bearing platform for the drum 2 to ensure the stability of subsequent operation. The drum 2 is stably lifted to the top of the bracket 7, and its bottom slot is used to tightly clamp with the bracket 7 to achieve reliable positioning.

[0031] The electrical components mentioned in this article are all connected to an external main controller and 220V mains electricity, and the main controller can be a conventional known device for controlling a computer or the like.

[0032] In summary, when using the dual-fuel steam boiler burning biomass and natural gas, first, turn on the biomass feeding device, feed fuel to the furnace 101 at a set rate, ignite the ignition material, and after the fuel is stably burned to form a fire, gradually increase the feeding amount and adjust the air volume to make the furnace temperature rise steadily. When using natural gas, first open the gas valve, ignite the natural gas using the ignition device according to the ignition procedure, and finely control the gas flow and air ratio through the gas regulating valve and the fan to achieve stable combustion. The temperature of the combustion chamber rises to generate smoke, which carries heat into the return pipe. The heat exchange process is started. Secondly, as the combustion continues, the high-temperature flue gas flows at a high speed in the second return pipe 104 and the third return pipe 105 of the heating structure 1, and fully exchanges heat with the water medium surrounding the drum 2. The water absorbs heat, heats up, and vaporizes, gradually forming steam that gathers in the upper space of the drum 2. The liquid level meter 9 monitors the water level in real time, and cooperates with the water pump 8 to replenish water as needed to maintain a stable water level, ensuring uninterrupted and efficient heat exchange. Then, when the steam pressure in the drum 2 reaches the set opening pressure of the steam valve pipe 12, the steam is transported to the outside through the steam valve pipe 12 as needed. The steam-using equipment can flexibly control the steam production and pressure by adjusting the fuel supply, biomass feeding speed or natural gas flow, air volume ratio and the opening of the steam valve pipe 12 according to the load change at the steam-using end, so as to meet the needs of different working conditions and ensure the stable operation of the entire production steam-using link. During the operation, the operator can use the fire viewing hole 303 and the fire viewing plate 302 of the side cover 5 to regularly check the combustion conditions of the backfire chamber 301 and the combustion chamber, judge the combustion quality according to the color and shape of the flame, adjust the combustion parameters, and monitor the flue gas temperature and pressure according to the feedback data of the instrument pipe 13. Force and other indicators, adjust the fan speed and fuel ratio as needed to maintain efficient and clean combustion, regularly inspect the connection and sealing of each component, and deal with leakage, wear and other problems in time. Finally, after shutdown, comprehensively check all components of the boiler, including the furnace 101 of the heating structure 1, whether the return pipe is deformed, ash accumulated, and coked, the cleanliness of the backfire chamber 301 of the backfire structure 3, the operating reliability of water system components such as the liquid level device 9 and the water supply pump 8, whether the smoke box and the flue have air leakage, scaling and other problems, record the equipment status, and make targeted plans for the next startup and regular maintenance.

[0033] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise one" do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0034] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dual-fuel steam boiler burning biomass and natural gas, comprising a heating structure (1), a backfire structure (3) and a boiler drum (2), characterized in that: A front smoke box (4) is fixedly mounted on one side of the boiler drum (2), a side cover (5) is fixedly mounted on one side of the boiler drum (2), a rear smoke box (6) is fixedly mounted on one side of the side cover (5), a bracket (7) is clamped on the bottom of the boiler drum (2), a water supply pump (8) is fixedly mounted on one side of the boiler drum (2), and a liquid level gauge (9) is clamped on the outer surface of the boiler drum (2).

2. A dual-fuel steam boiler burning biomass and natural gas according to claim 1, characterized in that: The heating structure (1) comprises a furnace (101), a front tube plate (102), a combustion chamber tube plate (103), a second return pipe (104), and a third return pipe (105); the furnace (101) is clamped at the middle of the front tube plate (102) and the combustion chamber tube plate (103); and the front tube plate (102) and the combustion chamber tube plate (103) are connected via the second return pipe (105).

3. A dual-fuel steam boiler burning biomass and natural gas according to claim 2, characterized in that: The backfire structure (3) comprises a backfire chamber (301), a fire viewing plate (302), and a fire viewing hole (303); one side of the backfire structure (3) is connected to the combustion chamber tube plate (103) of the heating structure (1).

4. A dual-fuel steam boiler burning biomass and natural gas according to claim 1, characterized in that: A lifting lug (10) is fixedly mounted on the top of the boiler drum (2), a safety valve pipe (11) is fixedly mounted on the top of the boiler drum (2), and a steam valve pipe (12) is fixedly mounted on the top of the boiler drum (2).

5. The dual-fuel steam boiler burning biomass and natural gas according to claim 1, characterized in that: An instrument tube (13) is fixedly mounted on the top of the front smoke box (4), and a flame injection port (14) is opened in the middle of the front smoke box (4).

6. A dual-fuel steam boiler burning biomass and natural gas according to claim 3, characterized in that: A connecting hole (15) is provided in the middle of the side cover (5), and a through hole (16) is provided in the middle of the side cover (5); the connecting hole (15) is clamped with one side of the third return pipe (105) of the heating structure (1), and the through hole (16) is clamped with the fire viewing hole (303) of the backfire structure (3).

7. The dual-fuel steam boiler burning biomass and natural gas according to claim 1, characterized in that: A drainage valve (17) is fixedly mounted on one side of the rear smoke box (6), and an economizer (18) is fixedly mounted on the top of the rear smoke box (6).

8. The dual-fuel steam boiler burning biomass and natural gas according to claim 1, characterized in that: A water inlet pipe (19) is fixedly installed on the top of the water supply pump (8), and a delivery pipeline (20) is fixedly installed on one side of the water supply pump (8).

9. The dual-fuel steam boiler burning biomass and natural gas according to claim 1, characterized in that: The bottom of the liquid level meter (9) is clamped with a display meter (21), and the bottom of the display meter (21) is clamped with a water delivery device (22).

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