Low-emission small methanol aluminum melting furnace and working method thereof

Abstract

The application discloses a low-emission small methanol aluminum melting furnace and a working method thereof. The methanol aluminum melting furnace comprises a furnace body, a methanol burner arranged at the bottom of the furnace body and a heat accumulating system. The methanol burner is arranged in the tangent direction of the bottom of the furnace body, the flame is sprayed into the furnace chamber of the melting furnace along the tangent direction from the burner outlet and the inner crucible is heated. The heat accumulating system comprises two heat accumulators. The flue gas discharged from the furnace body is selectively introduced into one of the heat accumulators to heat the heat accumulator. The outlet pipeline of the high-pressure fan is selectively introduced into one of the heat accumulators to preheat the air. Part of the preheated combustion-supporting air is introduced into the burner, mixed with the methanol gas and combusted. The other part of the preheated combustion-supporting air is introduced into the furnace chamber of the furnace body to realize staged combustion. The methanol aluminum melting furnace disclosed by the application has low energy consumption and low emission.

Description

Technical Field

[0001] This invention relates to the field of aluminum melting furnace technology, and in particular to a low-emission small methanol aluminum melting furnace and its operating method. Background Technology

[0002] With the development of the times, the demand for aluminum die castings in emerging fields such as electronic communication equipment, data centers and new energy vehicles is constantly increasing, and the production of aluminum die castings is inseparable from small aluminum melting furnaces; therefore, the energy-saving and emission-reduction transformation of small aluminum melting furnaces is imminent.

[0003] Traditional aluminum melting furnaces suffer from high energy consumption and serious pollution emissions. Although using methanol as fuel can partially solve these problems, the currently used methanol-reflective aluminum melting furnaces still have prominent issues such as difficulty in cold furnace start-up, serious heat loss, and poor fuel economy.

[0004] Field investigations revealed that the flue gas from coal-fired boilers had high dust concentrations and contained NO. x It produces multiple pollutants such as SO2; electric furnaces have low aluminum melting strength, high energy consumption, and require a separate transformer; natural gas furnaces have long construction cycles and high investment costs for pipeline transportation; while methanol is a clean energy source, its combustion temperature can meet the requirements for aluminum melting, and there is no need to lay pipelines or upgrade power supply facilities. Summary of the Invention

[0005] The purpose of this invention is to address the technical deficiencies of existing aluminum melting furnaces by providing a low-emission, small-scale methanol aluminum melting furnace.

[0006] Another object of the present invention is to provide a method of operating the methanol-aluminum melting furnace.

[0007] The technical solution adopted to achieve the purpose of this invention is:

[0008] A low-emission small-scale methanol-aluminum melting furnace includes a furnace body, a methanol burner disposed at the bottom of the furnace body, and a heat storage system, wherein:

[0009] The methanol burner is located tangentially at the bottom of the furnace body, and the flame is injected tangentially from the burner outlet into the furnace chamber of the aluminum melting furnace and heats the crucible inside.

[0010] The heat storage system includes two heat storage bodies. The flue gas discharged from the furnace body is selectively introduced into one of the heat storage bodies to heat the heat storage body. The outlet pipe of the high-pressure blower is selectively connected to one of the heat storage bodies to preheat the air. Part of the preheated combustion air is introduced into the burner and mixed with methanol gas for combustion. The other part enters the furnace chamber of the furnace body to achieve staged combustion.

[0011] In the above technical solution, the heat storage system includes a first heat storage body, a second heat storage body, and four two-position three-way valves, wherein:

[0012] The flue gas pipe of the furnace body is connected to one port of the first two-position three-way valve. The other two ports of the first two-position three-way valve are respectively connected to the first heat storage body and the second heat storage body through pipelines. The first heat storage body and the second heat storage body are respectively connected to a low-temperature flue gas discharge pipeline. The outlets of the two low-temperature flue gas discharge pipelines are respectively connected to the two ports of the second two-position three-way valve. The other port of the second two-position three-way valve is connected to the chimney to discharge flue gas.

[0013] The high-pressure blower outlet pipe is connected to one port of a third two-position three-way valve. The other two ports of the third two-position three-way valve are respectively connected to the first heat storage body and the second heat storage body through pipelines. Each of the first and second heat storage bodies is connected to a heat storage air connection pipeline. The outlets of the two heat storage air connection pipelines are connected to two ports of a fourth two-position three-way valve. The other port of the fourth two-position three-way valve is respectively connected to the burner air inlet pipe and the central air pipe through pipelines. The burner air inlet pipe is connected to the gas inlet of the burner on the furnace body, and the central air pipe is connected to the furnace chamber of the furnace body.

[0014] In the above technical solution, each two-position three-way valve is provided with a first cavity, a second cavity, and a third cavity. The first cavity is connected to the third cavity through a first connection port, and the second cavity is connected to the third cavity through a second connection port. The first cavity is provided with a first port, the second cavity is provided with a second port, and the third cavity is provided with a third port. When the first sealing plate is driven, it blocks the first connection port. When the second sealing plate is driven, it blocks the second connection port. When the first sealing plate blocks the first connection port, the second port is connected to the third port. When the second sealing plate blocks the second connection port, the first port is connected to the third port.

[0015] In the above technical solution, the sidewall of the furnace body has a multi-layer structure, consisting of an outer shell cylinder, a furnace lining, a furnace chamber, and a silicon carbide crucible and a furnace bottom liner disposed inside the furnace chamber. The silicon carbide crucible is located on top of the furnace bottom liner, and the nozzle of the burner is located inside the furnace chamber.

[0016] In the above technical solution, the outlet of the central air duct is located directly below the bottom opening of the furnace bottom liner to supply air into the silicon carbide crucible. The furnace bottom liner is provided with circumferentially arranged air outlets. The heated air supplied by the central air duct enters the furnace bottom liner through the bottom opening and is discharged through the air outlets, combining with the burner air inlet to achieve staged combustion of methanol.

[0017] In the above technical solution, the top of the furnace body is a cover, and the cover is provided with a smoke outlet, which is connected to the smoke exhaust pipe.

[0018] In the above technical solution, the cover includes a furnace top cover and an insulation cover disposed at the center of the furnace top cover.

[0019] In the above technical solution, the methanol burner is equipped with a dual-fluid atomizing nozzle and a spiral air pipe. The inlet end of the spiral air pipe is connected to the preheated air sent by the heat storage system, and the outlet end is connected to the dual-fluid atomizing nozzle. The dual-fluid atomizing nozzle is also connected to a methanol fuel pipe.

[0020] In the above technical solution, the methanol burner includes a burner housing and a silicon carbide flame guide nozzle. The silicon carbide flame guide nozzle is disposed on the outlet side of the burner housing. The gas in the burner housing is burned and ejected from the silicon carbide flame guide nozzle. The burner housing is provided with a gas inlet, which is connected to the inlet of the spiral air pipe through a pipeline. The burner housing is provided with a nozzle support, and the dual-fluid atomizing nozzle and ignition needle are both fixed on the nozzle support.

[0021] In another aspect of the present invention, the operating method of the small methanol aluminum melting furnace includes the following steps:

[0022] When the aluminum melting furnace is started, methanol and air enter the dual-fluid atomizing nozzle, forming a methanol-air mixture which is then sprayed out. The ignition needle ignites the mixture, which burns rapidly and heats the air spiral tube. The air inside the tube is heated to the set temperature in a short time. The latent heat of vaporization required for methanol evaporation is then provided by the high-temperature air inside the air spiral tube.

[0023] The high-temperature flue gas discharged from the furnace enters the regenerative system through the flue pipe. After exchanging heat with the honeycomb ceramic or alumina balls inside the first regenerative body, the high-temperature flue gas is discharged through the chimney, and the temperature of the first regenerative body rises. At the same time, the high-pressure air pump pumps air into the second regenerative body, which is then introduced into the air inlet of the burner through the burner air inlet pipe and into the furnace through the central air pipe.

[0024] When the temperature of the first heat storage body reaches the set value, the first heat storage body and the second heat storage body are switched. The high-temperature flue gas heats the second heat storage body, while the combustion air flows through the first heat storage body, is heated, and then enters the burner and furnace to achieve staged combustion of methanol.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. The addition of a dual-fluid atomizing nozzle and a stainless steel spiral air pipe inside the burner solves the problem of methanol's high latent heat of vaporization causing difficulty in atomizing and burning during cold furnace startup.

[0027] 2. This invention adds a switchable regenerative thermal system after the aluminum melting furnace's flue gas duct. This system utilizes the heat from the flue gas to heat the combustion air, significantly increasing the combustion air temperature while reducing the flue gas temperature and recovering the sensible heat of the flue gas. This substantially improves the thermal efficiency of the aluminum melting furnace. The regenerative system also monitors the flue gas outlet temperature. If the regenerative furnace suddenly experiences an abnormally high temperature, it indicates that unburned methanol is present in the flue gas and is burning within the regenerative furnace. In this case, the burner air volume should be increased immediately to ensure complete combustion of the methanol and avoid fuel waste.

[0028] 3. To reduce NO in aluminum melting furnaces x To reduce emissions, this invention adds a central air duct and a porous channel structure to the furnace bottom, which, combined with the burner air inlet, enables staged combustion of methanol, thereby reducing NO. x Furthermore, by utilizing the high-velocity flame generated by the burner nozzles to entrain the flue gas in the furnace, the oxygen concentration in the high-temperature flame zone is reduced, further suppressing NO emissions; x Staged combustion also ensures uniform heating of the crucible, thereby extending its service life. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a small methanol-aluminum melting furnace.

[0030] Figure 2 This is a schematic diagram of a small methanol-aluminum melting furnace.

[0031] Figure 3 The diagram shown is a schematic of the thermal storage system.

[0032] Figure 4 This is a schematic diagram of a two-position three-way valve.

[0033] Figure 5 This is a schematic diagram of the furnace body.

[0034] Figure 6 This is a schematic diagram of a methanol burner (part of the burner housing is omitted).

[0035] Figure 7 This is a schematic diagram of a methanol burner (the silicon carbide flame guide is omitted).

[0036] Figure 8 These are temperature cloud maps of the methanol reverberatory furnace chamber, temperature cloud maps of the burner cross section, and heat flux density cloud maps of the crucible wall.

[0037] Figure 9 This is a diagram showing the trajectory of methanol droplets inside a dual-fluid atomizing nozzle.

[0038] Figure 10 Geometric model and computational mesh diagram of the regenerator.

[0039] Figure 11 Temperature cloud map of the furnace chamber, temperature cloud map of the burner section, and heat flux density cloud map of the crucible wall.

[0040] In the diagram: 1-Chimney, 2-Second regenerator, 3-Central air duct, 4-Exhaust pipe, 5-Furnace body, 6-Methanol burner, 7-Burner inlet pipe, 8-First regenerator, 9-High-pressure blower outlet pipe, 10-First two-position three-way valve, 11-Low-temperature flue gas exhaust pipe, 12-Second two-position three-way valve, 13-Third two-position three-way valve, 14-Regenerator air connection pipe, 15-Fourth two-position three-way valve, 16-Cover, 17-First cavity, 18-Second cavity, 19-Third cavity, 20-First connection port, 21-Second connection port, 22 23-First port, 24-Second port, 25-Third port, 26-First cylinder, 27-Second cylinder, 28-First sealing plate, 29-Second sealing plate, 20-Outer shell, 31-Furnace lining, 32-Silicon carbide crucible, 33-Furnace bottom lining, 34-Smoke outlet, 35-Furnace top cover, 36-Insulation cover, 37-Air outlet, 38-Dual fluid atomizing nozzle, 39-Spiral air pipe, 40-Methanol fuel pipe, 41-Ignition needle, 42-Burner housing, 43-Silicon carbide flame guide nozzle, 44-Gas inlet, 45-Long ion probe. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0042] Example 1

[0043] A low-emission small-scale methanol-aluminum melting furnace includes a furnace body 5, a methanol burner 6 disposed at the bottom of the furnace body 5, and a heat storage system, wherein:

[0044] The methanol burner 6 is located tangentially at the bottom of the furnace body 5, and the flame is injected tangentially from the burner outlet into the furnace chamber of the aluminum melting furnace and heats the crucible inside.

[0045] The heat storage system includes two heat storage bodies. The flue gas discharged from the furnace 5 is selectively introduced into one of the heat storage bodies to heat it. The high-pressure blower outlet pipe selectively enters another heat storage body to preheat the air. Part of the preheated combustion air is introduced into the burner, mixed with methanol gas, and then burned. The other part enters the furnace chamber of the furnace 5 to achieve staged combustion, significantly reducing NO₂ levels. x Emissions.

[0046] Example 3

[0047] The heat storage system includes a first heat storage body 8, a second heat storage body 2, and four two-position three-way valves, wherein:

[0048] The flue gas pipe 4 of the furnace body 5 is connected to one port of the first two-position three-way valve 10. The other two ports of the first two-position three-way valve 10 are respectively connected to the first heat storage body 8 and the second heat storage body 2 through pipelines. The first heat storage body 8 and the second heat storage body 2 are respectively connected to a low-temperature flue gas discharge pipe 11. The outlets of the two low-temperature flue gas discharge pipes 11 are respectively connected to the two ports of the second two-position three-way valve 12. The other port of the second two-position three-way valve 12 is connected to the chimney 1 to discharge flue gas.

[0049] The high-pressure blower outlet pipe 9 is connected to one port of the third two-position three-way valve 13. The other two ports of the third two-position three-way valve 13 are respectively connected to the first heat storage body 8 and the second heat storage body 2 through pipelines. The first heat storage body 8 and the second heat storage body 2 are respectively connected to a heat storage air connection pipe 14. The outlets of the two heat storage air connection pipes 14 are connected to two ports of the fourth two-position three-way valve 15. The other port of the fourth two-position three-way valve 15 is respectively connected to the burner air inlet pipe 7 and the central air pipe 3. The burner air inlet pipe 7 is connected to the gas inlet of the burner 6 on the furnace body 5. The central air pipe 3 is connected to the furnace chamber 31 of the furnace body 5.

[0050] High-temperature flue gas discharged from furnace body 5 enters the regenerative system through exhaust pipe 4. After heat exchange with the honeycomb ceramic or alumina spheres inside the first regenerative body 8, the high-temperature flue gas is discharged through chimney 1, raising the temperature of the first regenerative body 8. Simultaneously, a high-pressure air pump pumps air into the second regenerative body 2, which then flows through the burner inlet pipe 7 to the burner 6's air inlet and through the central air duct 3 into the furnace 31. When the temperature of the first regenerative body 8 reaches the set value, the first and second regenerative bodies 8 switch. The high-temperature flue gas heats the second regenerative body 2, while the combustion air, heated by flowing through the first regenerative body 8, is then introduced into the burner 6 and the furnace 31. Experiments show that the temperature of the combustion air after heating the regenerative bodies is 1100K, from which the switching time of the reversing valve can be calculated to be 150s. The switching process is controlled by a computer system. Once the regenerative body reaches the set temperature, the reversing valve begins its cyclic operation.

[0051] Example 2

[0052] Preferably, each two-position three-way valve is provided with a first chamber 17, a second chamber 18, and a third chamber 19. The first chamber 17 is connected to the third chamber 19 through a first connection port 20, and the second chamber 18 is connected to the third chamber 19 through a second connection port 21. The first chamber 17 has a first port 22, the second chamber 18 has a second port 23, and the third chamber 19 has a third port 24. When the first sealing plate 27 is driven, it blocks the first connection port 20; when the second sealing plate 28 is driven, it blocks the second connection port 21. When the first sealing plate 27 blocks the first connection port 20, the second port 23 and the third port 24 are connected; when the second sealing plate 28 blocks the second connection port 21, the first port 22 and the third port 24 are connected. The first port 22, the second port 23, and the third port 24 are respectively connected to corresponding pipelines. Switching the port connection relationship can realize the switching of pipeline connection relationship and achieve the conversion of heat storage to heat release.

[0053] Furthermore, the first cavity 17 is provided with a first cylinder 25 at its top, and the second cavity 18 is provided with a second cylinder 26. The first sealing plate 27 is fixed on the piston rod of the first cylinder 25, and the second sealing plate 28 is fixed on the piston rod of the second cylinder 26. When the first cylinder 25 is started, the first sealing plate 27 blocks the first connection port 20, and when the second cylinder 26 is started, the second sealing plate 28 blocks the second connection port 21.

[0054] Example 3

[0055] To reduce NO in aluminum melting furnaces x Regarding emissions, this embodiment has made improvements to furnace body 5:

[0056] The sidewall of the furnace body 5 has a multi-layered structure, consisting of an outer shell cylinder 29, a furnace lining 30, a furnace chamber 31, and a silicon carbide crucible 32 and a furnace bottom liner 33 disposed inside the furnace chamber 31. The silicon carbide crucible 32 is located on top of the furnace bottom liner 33. The nozzle of the burner 6 is located inside the furnace chamber 31. The high-velocity flame generated by the burner 6 nozzle entrains the flue gas inside the furnace chamber 31, reducing the oxygen concentration in the high-temperature flame zone and suppressing NO. x generate.

[0057] The outlet of the central air duct 3 is located directly below the bottom opening of the furnace bottom liner 33 to supply air into the silicon carbide crucible 32. The furnace bottom liner 33 is provided with circumferentially arranged air outlets 37. The heated air supplied by the central air duct 3 enters the furnace bottom liner 33 through the bottom opening and exits through the air outlets. Combined with the air inlet of the burner 6, it achieves staged combustion of methanol and reduces NO. x Emissions.

[0058] The top of the furnace body 5 is a cover 16, and the cover 16 is provided with a smoke outlet 34, which is connected to the smoke exhaust pipe 4. The cover includes a furnace top cover 35 and a heat insulation cover 36 located in the center of the furnace top cover.

[0059] Example 4

[0060] Preferably, the methanol burner 6 is equipped with a dual-fluid atomizing nozzle 38 and a spiral air pipe 39. The inlet end 39-1 of the spiral air pipe 39 is connected to preheated air supplied by the heat storage system, and the outlet end 39-2 is connected to the dual-fluid atomizing nozzle 38. The air, preheated by the heat storage system, re-enters the spiral air pipe 39 for reheating before being sent into the dual-fluid atomizing nozzle 38. A methanol fuel pipe 40 is also connected to the dual-fluid atomizing nozzle 38. An ignition needle 41 is provided around the dual-fluid atomizing nozzle 38. The spiral air pipe 39 is partially coiled around the dual-fluid atomizing nozzle 38. When the dual-fluid atomizing nozzle 38 is ignited, it heats the air in the spiral air pipe 39. The methanol supplied through the methanol fuel pipe 40 and the air supplied through the spiral air pipe 39 are atomized and sprayed out through the dual-fluid atomizing nozzle 38, and combustion occurs under the action of the ignition needle 41.

[0061] When the aluminum melting furnace is started, methanol and air enter the dual-fluid atomizing nozzle, forming a methanol-air mixture which is then sprayed out. The ignition needle ignites the mixture, which burns rapidly and heats the air spiral tube. The air inside the tube is heated to 600K in a short time. Subsequently, the latent heat of vaporization required for methanol evaporation is provided by the high-temperature air inside the spiral tube.

[0062] Furthermore, the methanol burner 6 includes a burner housing 42 and a silicon carbide flame guide 43. The silicon carbide flame guide 43 is disposed on the outlet side of the burner housing 42. The gas in the burner housing 42 is combusted and ejected from the silicon carbide flame guide 43. The burner housing 42 is provided with a gas inlet 44, which is connected to the inlet of the spiral air pipe 39 through a pipe. A nozzle support is provided inside the burner housing 42, and the dual-fluid atomizing nozzle 38 and the ignition needle 41 are both fixed on the nozzle support. More preferably, a long ion probe 45 is also fixed on the nozzle support to monitor the combustion status.

[0063] Example 5

[0064] This embodiment verifies the performance of the aluminum melting furnace.

[0065] A three-dimensional numerical simulation of the flow and combustion processes inside an aluminum melting furnace (including the burner) was performed using the ANSYS Fluent platform. The flow, combustion, and crucible heat transfer distribution within the furnace were analyzed. The calculation was divided into two main parts. The first part calculated the cold flow of the methanol-air mixture inside the burner and furnace. A Realizable k-ε model was used to simulate the turbulent flow of the mixture in the burner and furnace, and the calculation was iteratively performed until convergence to obtain a reasonable cold flow field distribution inside the furnace.

[0066] The second part calculates the combustion of the gas-fuel mixture in the burner and furnace. The combustion temperature inside the furnace is high, and radiation is the primary heat transfer mechanism. The Discrete Ordinates model is used to calculate radiative heat transfer; a two-step turnbuffered reaction is used to simulate the methanol combustion reaction.

[0067] CH3OH + O2 → CO + 2H2O;

[0068] 2CO + O2 → 2CO2

[0069] First, numerical simulations were performed on the flow, combustion, and heat transfer processes inside the methanol reverberatory furnace. Based on the main design flaws revealed by the simulation results, targeted optimization designs were implemented for the methanol regenerative aluminum melting furnace designed in this example. The calculation results are as follows: Figure 8 As shown, the methanol fuel flow rate is 40 kg / h, and the air temperature is the ambient temperature of 300 K.

[0070] According to calculations, the average temperature of the reverberatory furnace chamber is approximately 1300 K, while the outlet flue gas temperature is 1215 K. This indicates that the thermal efficiency of heat exchange between the flue gas and the crucible within the furnace is extremely low, resulting in significant sensible heat loss and low overall thermal efficiency of the reverberatory furnace. Furthermore, due to… Figure 8 As shown, the heat release from the combustion of methanol swirl flame is mainly concentrated near the burner outlet, resulting in extremely uneven temperature distribution inside the furnace and uneven heating of the crucible.

[0071] To address the burner improvement scheme, we established a new burner geometric model. After meshing, we first performed simulation calculations on the dual-fluid atomizing nozzle to verify its atomization performance; the calculation results are as follows. Figure 9 As shown.

[0072] like Figure 9 Inside the burner, the high-temperature, high-pressure air completely evaporates the methanol droplets into methanol vapor, which improves the impact of the latent heat of vaporization of methanol on the cold start of the burner and can improve the thermal efficiency of the aluminum melting furnace.

[0073] To address the improvement plan, an internal geometric model (including the burner) of the regenerative methanol-aluminum melting furnace was established and meshed. For example... Figure 10 As shown.

[0074] The regenerative system used in this example converts the exhaust heat loss of the aluminum melting furnace into the sensible heat of the combustion air, significantly improving the thermal efficiency of the furnace. While meeting the aluminum melting requirements, it significantly reduces fuel consumption compared to a methanol reverberatory furnace design. The combustion air temperature in the calculations is 1100K, determined from experimental data. Calculation results show that when the methanol consumption in the regenerative furnace is 25 kg / h, the crucible heat absorption is 179 kW, which is basically equivalent to the crucible heat absorption at a methanol consumption of 40 kg / h in the reverberatory furnace. This indicates that the thermal efficiency of the regenerative methanol aluminum melting furnace is improved by up to 60% compared to the reverberatory furnace. The simulation results of the furnace temperature and crucible heat transfer distribution are as follows: Figure 11 As shown, the swirling combustion flame inside the furnace almost fills the furnace chamber, and the temperature distribution inside the furnace and the uniformity of the crucible heating are significantly improved. The local high heat transfer and uneven heating phenomena of the crucible are significantly improved.

[0075] The cost of melting aluminum per furnace is calculated based on fuel costs and electricity prices in Shandong Province. The savings in fuel and electricity are taken as net income, and the static cost payback period of the improved furnace is calculated.

[0076] (1) Cost of aluminum melting furnace: 500kg methanol regenerative furnace is about 52,500 yuan / set.

[0077] (2) Fuel Costs: The aluminum melting rate of the furnace was measured to be 150 kg / h, so it takes 6.67 hours to melt one ton of aluminum. The industrial methanol price in Shandong Province in 2021 was 2500 yuan / t. The fuel consumption of the methanol reverberatory furnace is 40 kg / h, and the power consumption is approximately 1 kW; the fuel consumption of the methanol regenerative furnace is approximately 25 kg / h, and the power consumption is approximately 2 kW. Therefore, the reverberatory furnace consumes 6.67 kWh / t of electricity, and the regenerative furnace consumes 13.34 kWh / t. The industrial and commercial electricity price in Shandong Province is approximately 0.85 yuan / kWh. Assuming each aluminum melting furnace melts aluminum for 6.67 hours per day, and calculating over 365 days a year, the cost distribution is shown in Table 1.

[0078] Table 1 Cost of Thermal Regenerator

[0079]

[0080] (3) Static cost payback period: 52500÷89180≈0.6 years.

[0081] Through experiments and calculations, the fuel consumption of the methanol reverberatory furnace and the regenerator was obtained as follows:

[0082] Table 2 Fuel Consumption of Reverberatory Furnace and Regenerator

[0083]

[0084] As shown in Table 2, under the same aluminum melting demand, the regenerative furnace can save 37.5% of methanol, thus improving fuel economy.

[0085] This work determined the composition and content of flue gas from reverberatory furnaces and regenerators through experiments and calculations (as shown in Table 3).

[0086] Table 3. Measurement results of flue gas composition and content of reverberatory furnace and regenerator.

[0087]

[0088] Experimental data shows that the CO emissions of the regenerative furnace are only 17% of those of the reverberatory furnace, and the methanol content in the flue gas is extremely low, indicating that the regenerative furnace has high safety; the NO emissions of the regenerative furnace are... x Emissions have been significantly reduced, achieving the goal of emission reduction.

[0089] In conclusion, this work has significant implications for energy conservation and emission reduction, and is worthy of application and promotion.

[0090] For ease of explanation, spatial relative terms such as “up,” “down,” “left,” and “right” are used in the embodiments to describe the relationship of one element or feature shown in the figures relative to another element or feature. It should be understood that, in addition to the orientations shown in the figures, spatial terms are intended to include different orientations of the device in use or operation. For example, if the device in the figures is inverted, an element described as being “down” of other elements or features would be positioned “up” of those other elements or features. Therefore, the exemplary term “down” can encompass both up and down orientations. The device may be positioned in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0091] Moreover, relational terms such as “first” and “second” are used merely to distinguish one component from another that has the same name, without necessarily requiring or implying any such actual relationship or order between the components.

[0092] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-emission small-scale methanol-aluminum melting furnace, characterized in that, It includes a furnace body, a methanol burner located at the bottom of the furnace body, and a heat storage system, wherein: The methanol burner is located tangentially at the bottom of the furnace body, and the flame is injected tangentially from the burner outlet into the furnace chamber of the aluminum melting furnace and heats the crucible inside. The heat storage system includes two heat storage bodies. The flue gas discharged from the furnace body is selectively introduced into one of the heat storage bodies to heat the heat storage body. The outlet pipe of the high-pressure blower is selectively connected to one of the heat storage bodies to preheat the air. Part of the preheated combustion air is introduced into the burner and mixed with methanol gas for combustion. The other part enters the furnace chamber of the furnace body to achieve staged combustion. The heat storage system includes a first heat storage body, a second heat storage body, and four two-position three-way valves, wherein: The flue gas pipe of the furnace body is connected to one port of the first two-position three-way valve. The other two ports of the first two-position three-way valve are respectively connected to the first heat storage body and the second heat storage body through pipelines. The first heat storage body and the second heat storage body are respectively connected to a low-temperature flue gas discharge pipeline. The outlets of the two low-temperature flue gas discharge pipelines are respectively connected to the two ports of the second two-position three-way valve. The other port of the second two-position three-way valve is connected to the chimney to discharge flue gas. The outlet pipe of the high-pressure blower is connected to one port of the third two-position three-way valve. The other two ports of the third two-position three-way valve are respectively connected to the first heat storage body and the second heat storage body through pipelines. The first heat storage body and the second heat storage body are respectively connected to a heat storage air connection pipeline. The outlets of the two heat storage air connection pipelines are connected to two ports of the fourth two-position three-way valve. The other port of the fourth two-position three-way valve is respectively connected to the burner air inlet pipe and the central air pipe through pipelines. The burner air inlet pipe is connected to the gas inlet of the burner on the furnace body. The central air pipe is connected to the furnace chamber of the furnace body. The sidewall of the furnace body has a multi-layer structure, consisting of an outer shell, a furnace lining, a furnace chamber, and a silicon carbide crucible and a furnace bottom liner disposed inside the furnace chamber, from the outside to the inside. The silicon carbide crucible is located on top of the furnace bottom liner, and the burner nozzle is located inside the furnace chamber. The outlet of the central air duct is located directly below the bottom opening of the furnace bottom liner to supply air into the silicon carbide crucible. The furnace bottom liner is provided with circumferentially arranged air outlets. The heated air supplied by the central air duct enters the furnace bottom liner through the bottom opening and is discharged through the air outlets, combining with the burner air inlet to achieve staged combustion of methanol.

2. The small methanol aluminum melting furnace as described in claim 1, characterized in that, Each two-position three-way valve is provided with a first chamber, a second chamber, and a third chamber. The first chamber is connected to the third chamber through a first connection port, and the second chamber is connected to the third chamber through a second connection port. The first chamber has a first port, the second chamber has a second port, and the third chamber has a third port. When the first sealing plate is driven, it blocks the first connection port. When the second sealing plate is driven, it blocks the second connection port. When the first sealing plate blocks the first connection port, the second port is connected to the third port. When the second sealing plate blocks the second connection port, the first port is connected to the third port.

3. The small methanol aluminum melting furnace as described in claim 1, characterized in that, The top of the furnace body is a cover, and the cover is provided with a smoke outlet, which is connected to the smoke exhaust pipe.

4. The small methanol aluminum melting furnace as described in claim 3, characterized in that, The cover includes a furnace top cover and an insulation cover located at the center of the furnace top cover.

5. The small methanol aluminum melting furnace as described in claim 1, characterized in that, The methanol burner is equipped with a dual-fluid atomizing nozzle and a spiral air pipe. The inlet end of the spiral air pipe is connected to preheated air supplied by the heat storage system, and the outlet end is connected to the dual-fluid atomizing nozzle. The dual-fluid atomizing nozzle is also connected to a methanol fuel pipe.

6. The small methanol aluminum melting furnace as described in claim 5, characterized in that, The methanol burner includes a burner housing and a silicon carbide flame guide nozzle. The silicon carbide flame guide nozzle is located on the outlet side of the burner housing. The gas in the burner housing is burned and ejected from the silicon carbide flame guide nozzle. The burner housing is provided with a gas inlet, which is connected to the inlet of the spiral air pipe through a pipeline. The burner housing is provided with a nozzle support, and the dual-fluid atomizing nozzle and ignition needle are both fixed on the nozzle support.

7. The operating method of the small methanol aluminum melting furnace as described in any one of claims 1-6, characterized in that, When the aluminum melting furnace is started, methanol and air enter the dual-fluid atomizing nozzle, forming a methanol-air mixture which is then sprayed out. The ignition needle ignites the mixture, which burns rapidly and heats the air spiral tube. The air inside the tube is heated to the set temperature in a short time. The latent heat of vaporization required for methanol evaporation is then provided by the high-temperature air inside the air spiral tube. The high-temperature flue gas discharged from the furnace enters the regenerative system through the flue pipe. After exchanging heat with the honeycomb ceramic or alumina balls inside the first regenerative body, the high-temperature flue gas is discharged through the chimney, and the temperature of the first regenerative body rises. At the same time, the high-pressure air pump pumps air into the second regenerative body, which is then introduced into the air inlet of the burner through the burner air inlet pipe and into the furnace through the central air pipe. When the temperature of the first heat storage body reaches the set value, the first heat storage body and the second heat storage body are switched. The high-temperature flue gas heats the second heat storage body, while the combustion air flows through the first heat storage body, is heated, and then enters the burner and furnace to achieve staged combustion of methanol.

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