Condensing methanol vaporizing combustion heating stove and control method thereof

Abstract

The application discloses a condensing methanol vaporization combustion heating stove and a control method thereof, and belongs to the technical field of clean energy and heat energy engineering, and aims to solve the problems of poor atomization, insufficient combustion, large combustion noise and low thermal efficiency of the existing methanol heating stove. The heating stove comprises a shell, a back plate, a flow dividing cylinder, a combustion cylinder, a cooling pipe, a vaporization pipe, a nozzle and a cyclone disc, the number of circumferential holes of the front half part of the flow dividing cylinder is less than that of the rear half part; the vaporization pipe is arranged in the high-temperature flame area of the combustion cylinder and is communicated with the fuel inlet and the nozzle respectively. Liquid methanol is pre-vaporized by an initial heat source and is sprayed out from the nozzle, mixed with the cyclone air and combusted in the combustion cylinder; part of the heat generated by the combustion maintains the continuous vaporization of the subsequent methanol, and the rest of the heat heats the circulating water through the cooling pipe; the high-temperature flue gas exchanges heat with the cooling pipe through the flow dividing cylinder and recovers the latent heat by condensation. The application can realize the energy self-sustaining of the methanol gas phase mixed combustion and vaporization process and is suitable for heating.

Description

Technical Field

[0001] This invention relates to the field of clean energy and thermal energy engineering technology, specifically to a condensing methanol vaporization combustion heating furnace and its combustion control method, which first vaporizes liquid methanol fuel into a gas phase and then mixes it with air for combustion. Background Technology

[0002] In areas where natural gas is unavailable and the power grid load is insufficient, methanol wall-hung boilers have seen significant market opportunities. However, existing technologies, due to their use of atomization combustion, suffer from incomplete combustion, low thermal efficiency, and high combustion noise, resulting in high operating costs and a poor user experience, thus limiting the development of methanol wall-hung boilers. Most existing methanol heating boilers employ traditional mechanical atomization or pressure atomization combustion methods. Because liquid methanol has a high latent heat of vaporization, direct atomization combustion often fails to achieve uniform molecular-level mixing with air in a very short time, easily leading to carbon buildup and oil dripping in the furnace. Furthermore, it cannot achieve the precise fully or semi-premixed combustion seen in gas-fired wall-hung boilers. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a condensing methanol vaporization combustion heating furnace and its control method, which mainly solves the problems of high noise, incomplete combustion and low thermal efficiency of methanol heating furnaces in the prior art.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A condensing methanol vaporization combustion heating furnace and its control method are disclosed, comprising a shell and a back plate. The bottom of the shell is provided with a hot water outlet, a condensate outlet, and a cold water inlet. The interior of the shell contains a cooling pipe, with its two ends connected to the cold water inlet and the hot water outlet, respectively. Inside the cooling pipe is a distribution cylinder, with a heat insulation pad between the distribution cylinder and the back plate. An air inlet is located at the lower part of the back plate. A nozzle is installed at the center of the back plate, with an ionization rod and an ignition needle installed on one side of the nozzle. A swirl plate is located at the front end of the nozzle, and a vaporization tube is located at the front end of the swirl plate. One end of the vaporization tube is connected to the nozzle, and the other end is connected to the fuel inlet. A combustion chamber is located between the vaporization tube and the distribution cylinder.

[0006] A further improvement of the present invention is that a number of small holes are opened on the flow divider, and the diameter of the holes is 7~9mm. Furthermore, the number of circumferential holes in the front half of the flow divider is lower than that in the rear half, and the ratio of the number of circumferential holes in the front half to the rear half is 1:1.25~1.75.

[0007] A further improvement of the present invention is that the nozzle orifice diameter is 1.4~1.6mm.

[0008] A further improvement of the present invention is that a number of guide vanes are evenly arranged on the swirl disk along the circumferential direction, and the angle between the guide vanes and the conical surface of the swirl disk is 5~20°.

[0009] A further improvement of this invention is that the nozzle, swirl plate, and vaporization tube are on the same central axis.

[0010] A further improvement of this invention is that the vaporization tube has an inner diameter of 6-8 mm, a wall thickness of 1 mm, an effective heat exchange area of ​​0.006-0.01 m² for every 1 kg / h of methanol, and is made of copper.

[0011] A further improvement of this invention is that the vaporization tube is arranged in the high-temperature zone of the flame inside the combustion chamber, and the liquid methanol inside the tube is heated and vaporized by the heat radiation and convection heat exchange generated by the combustion in the combustion chamber.

[0012] A further improvement of this invention is that a ring of evenly distributed square high-temperature exhaust ports is opened at the tail end of the combustion cylinder, with 11 to 13 square holes, each with an area of ​​0.045 m².

[0013] The steps of this invention's device are as follows: S1, Pre-vaporization: Liquid methanol is pumped into the vaporization tube, absorbs heat under the action of an initial heat source, undergoes a phase change, and is converted into methanol fuel vapor; S2, Injection and entrainment: Methanol fuel vapor is transported to the fuel inlet through a pipeline, and is ejected at high speed from the nozzle, entraining some of the surrounding air to complete a preliminary mixing; S3, Swirl premixing: Combustion air is blown in through the air inlet, passes through the swirling disk to form a high-speed rotating airflow, and mixes turbulently with the methanol vapor in front of the nozzle to form a uniformly concentrated combustible mixture; S4, Stable combustion and energy self-sustaining: The combustible mixture is ignited by the ignition needle in the combustion chamber, releasing heat; part of the heat generated by combustion is transferred to the vaporization tube located in the combustion chamber to maintain the continuous vaporization of the subsequently entering liquid methanol; the remaining main heat is transferred to the external cooling pipe to heat the heating circulating water; S5, Condensation and flue gas exhaust: The flue gas after heat exchange flows through the distributor, the flue gas temperature drops below the dew point, water vapor condenses and releases the latent heat of vaporization, the low-temperature flue gas is discharged from the flue gas outlet, and the generated condensate is discharged from the condensate outlet.

[0014] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention converts liquid fuel into a gaseous state before entering the combustion zone, achieving true gas-phase combustion and fundamentally eliminating the oil dripping and carbon buildup caused by poor atomization in traditional methanol stoves; it adopts a "nozzle + swirl plate" structure, utilizing the turbulence effect of high-speed airflow to achieve perfect mixing of fuel vapor and air, resulting in complete combustion; during normal operation, the energy of the vaporization pipe (vaporizer) comes from the residual heat of combustion in the furnace itself, eliminating the need for additional electrical energy consumption to maintain fuel boiling, thus greatly reducing energy consumption; at the same time, it is combined with a condensation structure to recover the latent heat of flue gas, resulting in extremely high thermal efficiency.

[0015] Furthermore, the nozzle orifice diameter of this invention is 1.4~1.6 mm. If the orifice diameter is too small, the flow resistance of methanol vapor and the back pressure of the vaporization tube increase significantly, easily causing fluctuations in the methanol supply flow rate. Simultaneously, excessively high outlet velocity and axial momentum may weaken the stabilizing effect of the swirling recirculation zone, causing the flame to elongate or rise. If the orifice diameter is too large, the vapor jet velocity and its entrainment and shearing effect on the surrounding air are weakened, which is not conducive to the rapid and uniform mixing of methanol vapor and air, easily forming a localized rich combustion zone and exacerbating incomplete combustion. Therefore, limiting the orifice diameter to 1.4~1.6 mm can balance fuel flow capacity, jet mixing intensity, and flame stability.

[0016] Furthermore, the vaporization tube of this invention has an inner diameter of 6-8 mm and a wall thickness of 1 mm, with an effective heat exchange area of ​​0.006-0.01 m² per 1 kg / h of methanol. If the inner diameter is too small, the flow rate and pressure drop between the gas and liquid phases during methanol vaporization increase, easily leading to higher back pressure and flow pulsation. If the inner diameter is too large, the flow rate and convective heat transfer intensity within the tube decrease at the same flow rate, which is detrimental to uniform and complete methanol vaporization. An insufficient effective heat exchange area results in insufficient heat absorption, causing the outlet methanol to carry droplets or have a lower vapor temperature. An excessively large area increases the tube length, flow resistance, and thermal inertia, and may cause the fully vaporized methanol vapor to be overheated, affecting the temperature stability of the combustion zone. For copper vaporization tubes, a wall thickness that is too thin is detrimental to ensuring pressure resistance and high-temperature durability, while a wall thickness that is too thick increases thermal inertia and delays start-up response. Therefore, the above parameters achieve a balance between vaporization capacity, flow resistance, heat transfer response, and structural strength, ensuring continuous and stable methanol vaporization.

[0017] Furthermore, this invention provides several diversion holes with a diameter of 7–9 mm on the diversion cylinder. If the hole diameter is too large, the total open area increases, the average jet velocity at the orifice decreases, and the impact and disturbance effect on the cooling coil surface weakens, which is detrimental to enhancing convective heat transfer on the flue gas side. If the hole diameter is too small, the flow resistance and back pressure inside the diversion cylinder increase, limiting flue gas discharge. Even if the local jet velocity is increased, it is difficult to balance flue gas discharge smoothness with overall heat exchange effect. Therefore, setting the diversion hole diameter to 7–9 mm achieves a better balance between jet scouring intensity, flow resistance, and flue gas discharge capacity. The number of diversion holes arranged circumferentially in the front half of the diversion cylinder is less than that in the rear half, and the ratio of the number of holes arranged circumferentially in the front and rear halves is 1:(1.25–1.75). This non-uniform porous structure can suppress the concentrated discharge of high-temperature flue gas in the front half, guide some of the flue gas to continue to be transported to the rear half, and under the guidance of the end flow, it will be turned or partially recirculated before being discharged from the rear half. This allows the flue gas to more evenly scour the front and rear areas of the cooling coil. At the same time, this structure can prevent the high-temperature flue gas from being discharged too quickly, appropriately prolonging its residence time in the combustion and heat exchange areas. This helps maintain a relatively stable high-temperature environment, enhances the heat feedback effect of the porous medium, and promotes further oxidation of methanol vapor and incomplete combustion products, thereby improving the degree of combustion completeness and boiler thermal efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a condensing methanol vaporization combustion heating furnace.

[0019] Figure 2 It is a swirl disk.

[0020] Figure 3 It is a combustion chamber.

[0021] Explanation of reference numerals in the attached diagram: 1-Air inlet; 2-Ionizing rod; 3-Fuel inlet; 4-Nozzle; 5-Ignition needle; 6-Swirl plate; 7-Diverter; 8-Flue gas outlet; 9-Combustion tube; 10-Vaporization pipe; 11-Cooling pipe; 12-Heating water supply inlet; 13-Condensate outlet; 14-Heating return water inlet; 15-Shell; 16-Back plate; 17-Insulation pad; 601-Guide vane; 602-Conical surface; 901-Exhaust port. Detailed Implementation

[0022] like Figure 1 and Figure 2As shown, the present invention includes a housing 15 and a back plate 16. The bottom of the housing 15 is provided with a hot water outlet 12, a condensate outlet 13, and a cold water inlet 14. Inside the housing is a cooling pipe 11, with both ends connected to the cold water inlet 14 and the hot water outlet 12, respectively. The inner side of the cooling pipe 11 is a distribution cylinder 7, with several small holes of 7-9 mm in diameter. The number of circumferential holes in the front half of the distribution cylinder 7 is less than that in the rear half, with a ratio of 1:1.25-1.75. A heat insulation pad 17 is installed between the distributor 7 and the back plate 16. An air inlet 1 is provided at the lower part of the back plate 16. A nozzle 4 is installed at the center of the back plate 16, with a nozzle orifice diameter of 1.4~1.6mm. An ion rod 2 and an ignition needle 5 are installed on one side of the nozzle 4. The front end of the nozzle 4 is a swirl plate 6, on which several guide vanes 601 are evenly arranged along the circumference. The angle between the guide vanes 601 and the conical surface 602 of the swirl plate 6 is 5~20°. The front end of the swirl plate 6 is a vaporization tube 10, with an inner diameter of 6~8mm and a wall thickness of 1mm. The effective heat exchange area corresponding to 1kg / h of methanol is 0.006~0.01m², and the material is copper. One end of the vaporization pipe 10 is connected to the nozzle 4, and the other end is connected to the fuel inlet 3. A combustion cylinder 9 is set between the vaporization pipe 10 and the diverter cylinder 7. A ring of circumferentially distributed square high-temperature exhaust ports 901 is opened at the tail of the combustion cylinder 9. The number of square holes is 11 to 13, and the area of ​​each hole is 0.045m².

[0023] In this invention, the nozzle 4, the swirl disk 6, and the vaporization tube 10 are on the same central axis.

[0024] In this invention, the vaporization tube 10 is arranged in the high-temperature zone of the flame inside the combustion chamber 9, and the liquid methanol inside the tube is heated and vaporized by the heat radiation and convection heat exchange generated by the combustion in the combustion chamber 9.

[0025] The working process of this device is as follows: S1, Pre-vaporization: Liquid methanol is pumped into the vaporization pipe 10, and under the action of the initial heat source, it absorbs heat and undergoes a phase change, transforming into methanol fuel vapor; S2, Injection and ejection: Methanol fuel vapor is transported to the fuel inlet (3) through the pipeline, and is ejected at high speed from the nozzle 4, entraining some of the surrounding air to complete a preliminary mixing; S3, Swirl premixing: Combustion air is blown in from the air inlet 1, passes through the swirling disk 6 to form a high-speed rotating airflow, and mixes with methanol vapor in front of the nozzle 4 to form a uniformly concentrated combustible mixture. S4. Stable Combustion and Self-Sustaining Energy: The combustible gas mixture is ignited by the ignition needle 5 in the combustion chamber 9, releasing heat; part of the heat generated by combustion is transferred to the vaporization pipe 10 located in the combustion chamber 9 to maintain the continuous vaporization of the subsequently entering liquid methanol; the remaining main heat is transferred to the external cooling pipe 11 to heat the heating circulating water; S5. Condensation and Flue Gas Exhaust: The flue gas after heat exchange flows through the diverter 7, and the flue gas temperature drops below the dew point. Water vapor condenses and releases the latent heat of vaporization. The low-temperature flue gas is discharged from the flue gas outlet 8, and the generated condensate is discharged from the condensate outlet 13.

Claims

1. A condensing methanol vaporization combustion heating furnace and its control method, comprising a shell (15) and a back plate (16), wherein the bottom of the shell (15) is provided with a hot water outlet (12), a condensate outlet (13) and a cold water inlet (14), and the inside of the shell is a cooling pipe (11), wherein the two ends of the cooling pipe (11) are connected to the cold water inlet (14) and the hot water outlet (12) respectively. The inner side of the cooling pipe (11) is a flow divider (7). A heat insulation pad (17) is provided between the flow divider (7) and the back plate (16). An air inlet (1) is provided at the bottom of the back plate (16). A nozzle (4) is installed in the center of the back plate (16). An ion rod (2) and an ignition needle (5) are installed on one side of the nozzle (4). The front end of the nozzle (4) is a swirl plate (6). The front end of the swirl plate (6) is a vaporization pipe (10). One end of the vaporization pipe (10) is connected to the nozzle (4), and the other end is connected to the fuel inlet (3). A combustion tube (9) is provided between the vaporization pipe (10) and the flow divider (7).

2. The condensing methanol vaporization combustion heating boiler and its control method according to claim 1, characterized in that: The diverter (7) has several small holes with a diameter of 7-9 mm. The number of holes along the circumference in the front half of the diverter (7) is lower than that in the back half, and the ratio of the number of holes along the circumference in the front half to the number of holes along the circumference in the back half is 1:1.25-1.

75.

3. The condensing methanol vaporization combustion heating boiler and its control method according to claim 1, characterized in that: The nozzle (4) has a nozzle orifice diameter of 1.4~1.6mm.

4. The condensing methanol vaporization combustion heating boiler and its control method according to claim 1, characterized in that: The swirl disk (6) is uniformly arranged with several guide vanes (601) along the circumferential direction. The angle between the guide vanes (601) and the conical surface (602) of the swirl disk (6) is 5~20°.

5. The condensing methanol vaporization combustion heating boiler and its control method according to claim 1, characterized in that: The nozzle (4), swirl plate (6), and vaporization tube (10) are on the same axis center line.

6. A condensing methanol vaporization combustion heating boiler according to claim 1, characterized in that: The vaporization tube (10) has an inner diameter of 6~8mm, a wall thickness of 1mm, an effective heat exchange area of ​​0.006~0.01m² for every 1kg / h of methanol, and is made of copper.

7. The condensing methanol vaporization combustion heating boiler and its control method according to claim 1, characterized in that: The vaporization tube (10) is arranged in the high-temperature zone of the flame inside the combustion chamber (9), and uses the heat radiation and convection heat exchange generated by the combustion in the combustion chamber (9) to heat and vaporize the liquid methanol in the tube.

8. The condensing methanol vaporization combustion heating boiler and its control method according to claim 1, characterized in that: The combustion cylinder (9) has a ring of evenly distributed square high-temperature exhaust ports (901) at its tail end. The number of square ports is 11 to 13, and the area of ​​each port is 0.045 m². 2 .

9. A combustion control method for a condensing methanol vaporization combustion heating boiler according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Pre-vaporization: Liquid methanol is pumped into the vaporization pipe (10), absorbs heat under the action of the initial heat source and undergoes a phase change, transforming into methanol fuel vapor; S2. Injection and ejection: Methanol fuel vapor is transported to the fuel inlet (3) through the pipeline and ejected at high speed from the nozzle (4), ejecting some of the surrounding air to complete a preliminary mixing; S3. Swirl premixing: Combustion air is blown in from the air inlet (1), passes through the swirl plate (6) to form a high-speed rotating airflow, and mixes with methanol vapor in front of the nozzle (4) to form a uniformly concentrated combustible mixture; S4. Stable combustion and energy Self-sustaining: The combustible mixture is ignited by the ignition needle (5) in the combustion chamber (9) and releases heat; part of the heat generated by combustion is transferred to the vaporization tube (10) located in the combustion chamber (9) to maintain the continuous vaporization of the subsequently entering liquid methanol; the remaining main heat is transferred to the external cooling tube (11) to heat the heating circulating water; S5, condensation and exhaust: the flue gas after heat exchange flows through the diverter (7), the flue gas temperature drops below the dew point, the water vapor condenses and releases the latent heat of vaporization, the low temperature flue gas is discharged from the flue gas outlet (8), and the generated condensate is discharged from the condensate outlet (13).

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