Negative pressure furnace

Abstract

This utility model discloses a negative pressure furnace, which relates to the field of gas stove technology. The negative pressure furnace includes a pot body, a burner, a combustion heat exchanger, a waste gas heat exchanger, and a fan. The combustion heat exchanger is arranged at the bottom of the pot body and includes an outer plate, a bottom plate, and multiple arc-shaped fins. The waste gas heat exchanger includes a shell and heat exchange fins. This utility model can mainly form a negative pressure suction mode and significantly improve heat transfer efficiency through the fin structure. It also achieves dual energy saving and deep recovery of waste heat.

Description

Technical Field

[0001] This utility model relates to the field of gas stove technology, and in particular to a negative pressure furnace. Background Technology

[0002] Most commercial or industrial gas stoves (such as sugar pots and large soup pots) currently use positive pressure forced-air combustion or natural aspiration combustion. In positive pressure forced-air combustion, the blower is located at the front of the burner, blowing air into the furnace. This method has significant drawbacks: First, the flame, after impacting the bottom of the pot under positive pressure, quickly rebounds and spreads outwards, resulting in a short contact time and limited contact area between the flame and the pot bottom. A large amount of heat energy is lost to the surrounding environment with the overflowing high-temperature flue gas, leading to low thermal efficiency and excessively high temperatures in the kitchen working environment. Second, traditional stoves typically release the high-temperature exhaust gas directly into the atmosphere, leaving a large amount of waste heat unused, resulting in significant energy waste. Furthermore, due to the lack of an effective exhaust gas guidance mechanism, combustion is often incomplete, easily producing high levels of carbon monoxide emissions. Therefore, there is an urgent need for a negative pressure stove that can improve thermal efficiency, recover waste heat, and improve combustion quality. Utility Model Content

[0003] The purpose of this invention is to solve the technical problems existing in the prior art. Therefore, this invention provides a negative pressure furnace.

[0004] The negative pressure furnace according to an embodiment of the present utility model includes: The pot body; Burner; A combustion heat exchanger is arranged at the bottom of the pot body. The combustion heat exchanger includes an outer plate, a bottom plate, and multiple arc-shaped fins. The outer plate is located below the pot body, and its upper end is welded to the bottom surface of the pot body. The bottom plate is welded to the lower end surface of the outer plate. The bottom plate is provided with a gas inlet and an exhaust outlet. The multiple arc-shaped fins are arranged at intervals along the circumference of the pot body. The arc-shaped fins are arranged on the inner circumference of the outer plate. The outer plate, the bottom plate, and the pot body form an inner cavity. A waste gas heat exchanger includes a shell and heat exchange fins. The shell has a waste gas chamber and a cooling water chamber that are not interconnected. The outer peripheral wall of the shell has an inlet and an outlet that communicate with the cooling water chamber. The shell also has an air inlet and an air outlet that communicate with the waste gas chamber. Part of the structure of the heat exchange fins is located inside the waste gas chamber, and part of the structure of the heat exchange fins is located inside the cooling water chamber. A fan, the air inlet of which is connected to the air outlet.

[0005] The negative pressure furnace according to the first aspect of the present invention has at least the following beneficial effects: 1. Extremely high thermal efficiency and combustion quality: This invention utilizes a fan positioned at the end to create a negative pressure suction mode, combined with the sealed structure of the combustion heat exchanger (the outer plate, bottom plate, and pot body forming an inner cavity), forcibly drawing in and mixing external air and combustion gas. The arc-shaped fins not only significantly increase the heating area at the bottom of the pot body but also guide the high-temperature airflow to flow closely along the bottom of the pot (wall adhesion effect), extending the residence time of the high-temperature flue gas in the furnace cavity, thereby significantly improving heat transfer efficiency.

[0006] 2. Dual Energy Saving and Deep Waste Heat Recovery: This negative pressure furnace integrates a waste gas heat exchanger. The high-temperature waste gas after combustion must pass through the waste gas heat exchanger before being discharged. The heat exchange fins efficiently transfer heat from the waste gas chamber to the water in the cooling water chamber, achieving cascaded energy utilization. The heated water can be used later, thus recovering energy, reducing the exhaust gas temperature, protecting the downstream fan, and achieving energy saving and environmental protection.

[0007] 3. Compact structure and improved environment: The overall structure integrates the combustion, heat exchange and exhaust systems into one unit. The negative pressure working mode avoids the overflow of exhaust gas and flame, effectively reducing the ambient temperature around the equipment and improving the working environment for operators.

[0008] According to some embodiments of this utility model, the combustion heat exchanger further includes a guide plate, which is located between the arc-shaped fins and the guide plate. The top surface of the guide plate is welded and fixed to the bottom surface of the arc-shaped fins. The guide plate divides the inner cavity into an upper cavity and a lower cavity. The arc-shaped fins are located in the upper cavity. A guide nozzle is provided at the center of the guide plate, which connects the gas inlet and the upper cavity. A through hole is provided at the edge of the guide plate to connect the upper cavity and the lower cavity.

[0009] According to some embodiments of the present invention, the guide plate has an inclined section for guiding the flame flowing upward from the air guide nozzle to diffuse obliquely upward to the periphery of the guide plate.

[0010] According to some embodiments of the present invention, the outer plate includes an upper section plate and a lower section plate, the upper section plate is located above the lower section plate, and the guide plate is welded between the upper section plate and the lower section plate.

[0011] According to some embodiments of the present invention, the combustion heat exchanger further includes an inner circumference plate, which is an annular plate located on the inner periphery of the outer circumference plate. The lower end face of the inner circumference plate is welded and sealed to the guide plate, and the upper end face of the inner circumference plate is spot-welded to the bottom surface of the pot body. There is a gap between the inner circumference plate and the pot body.

[0012] According to some embodiments of the present invention, the housing includes an upper shell and a lower shell, the heat exchange fins are welded to a plate, the heat exchange fins include upper fins and lower fins, the upper fins are welded to the upper end face of the plate, the lower fins are welded to the lower end face of the plate, the plate is welded between the upper shell and the lower shell, the upper fins are located in the cooling water chamber, and the lower fins are located in the exhaust gas chamber.

[0013] According to some embodiments of the present invention, a heat storage brick is provided between the burner and the gas inlet, and the heat storage brick surrounds the outer periphery of the gas inlet.

[0014] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the structure of a negative pressure furnace according to some embodiments of the present invention; Figure 2 This is a schematic diagram of the structure of a negative pressure furnace according to some embodiments of the present invention; Figure 3 This is a cross-sectional view of a negative pressure furnace according to some embodiments of the present invention; Figure 4 for Figure 3 Enlarged view of point A in the middle; Figure 5 This is an exploded view of the negative pressure furnace according to some embodiments of the present invention; Figure 6 This is an exploded view of the negative pressure furnace according to some embodiments of the present invention; Figure 7 This is a schematic diagram of the structure of the pot body and arc-shaped fins of the negative pressure furnace according to some embodiments of the present invention; Figure 8 This is a schematic diagram of the structure of the guide plate of the negative pressure furnace in some embodiments of the present invention; Figure 9 This is an exploded view of the waste gas heat exchanger of the negative pressure furnace in some embodiments of this utility model; Figure 10 This is a schematic diagram of the mounting frame for the heat storage bricks according to some embodiments of this utility model.

[0016] Figure label: 1000 negative pressure furnace; Pot body 100; Combustion heat exchanger 200, outer perimeter plate 210, upper section plate 212, lower section plate 213, bottom plate 220, gas inlet 221, exhaust outlet 222, connecting nozzle 223, arc-shaped fins 230, guide plate 240, guide nozzle 241, inclined section 242, through hole 243, upper cavity 244, lower cavity 245, inner perimeter plate 250, gap 251, heat storage brick 260, mounting bracket 270, U-shaped groove 271; Waste gas waste heat exchanger 300, shell 310, waste gas chamber 311, cooling water chamber 312, water inlet 313, water outlet 314, air inlet 315, air outlet 316, upper shell 317, lower shell 318, heat exchange fins 320, upper fins 321, lower fins 322, plate 330; Burner 400; Fan 500. Detailed Implementation

[0017] Reference Figures 1 to 3 As shown, this is a negative pressure furnace 1000 provided in an embodiment of the present invention. The negative pressure furnace 1000 is mainly used in commercial kitchen equipment, food processing industrial cooking equipment, or large-scale heating equipment. Its core components include a pot body 100, a combustion heat exchanger 200, a waste gas heat exchanger 300, a burner 400, and a fan 500. Before elaborating on the specific structure, the overall thermodynamic cycle working principle of this invention is briefly described: When the system starts, the fan 500 first works to establish a negative pressure environment. The burner 400 sprays gas and ignites it. Under the strong negative pressure suction generated by the fan 500, fresh external air is forcibly drawn in and mixes with the gas inside the combustion heat exchanger 200 for combustion. The high-temperature flue gas generated by combustion undergoes an initial high-efficiency heat exchange with the pot body 100 inside the combustion heat exchanger 200, transferring most of the heat energy to the medium inside the pot body 100. Subsequently, the waste gas after the initial heat exchange is not directly discharged into the atmosphere, but is guided into the waste gas heat exchanger 300. Inside the waste heat exchanger 300, high-temperature waste gas undergoes secondary heat exchange with circulating cooling water. After the waste gas temperature is significantly reduced, it is discharged through the fan 500. The cooling water that has absorbed the waste heat of the waste gas is transported to a water storage device for subsequent use, thereby realizing the cascade utilization of energy.

[0018] Specifically, refer to Figure 3 , Figure 6 and Figure 7As shown, the combustion heat exchanger 200 is the core heat-absorbing component of this device. It is designed to be installed close to the bottom of the pot body 100 to minimize the heat conduction distance. The combustion heat exchanger 200 mainly consists of an outer plate 210, a bottom plate 220, and multiple arc-shaped fins 230. The outer plate 210 is preferably made of high-temperature resistant stainless steel rolled into a circular plate structure, serving as the outer wall of the entire combustion chamber. The upper end face of the outer plate 210 is sealed to the bottom surface of the pot body 100 through a continuous welding process, thus establishing the boundary of the top of the combustion chamber. The lower end face of the outer plate 210 is welded to the edge of the bottom plate 220, which is a circular steel plate. Thus, the outer plate 210, the bottom plate 220, and the bottom surface of the pot body 100 together form a relatively closed negative pressure combustion chamber. Inside this chamber, multiple arc-shaped fins 230 are evenly spaced along the circumference. Each arc-shaped fin 230 extends vertically, with its upper surface tightly welded to the bottom surface of the pot body 100, ensuring that heat can be rapidly transferred to the pot body 100 directly through metal heat conduction. Viewed from above, these multiple arc-shaped fins 230 are arranged radially, or they can be understood as a combination of multiple arc-shaped fins 230 forming a disc-shaped radiator structure with a swirling flow channel. A gas inlet 221 is provided at the geometric center of the base plate 220, and the nozzle assembly of the burner 400 is installed at this gas inlet 221 to inject fuel into the center of the furnace cavity. A dedicated exhaust outlet 222 is also provided on the base plate 220 to discharge the flue gas after combustion. An air inlet can be provided on the outer peripheral wall of the outer plate 210 to introduce combustion air; alternatively, an air inlet can be omitted, as the outer wall of the burner 400 has gaps connecting to the outside air, allowing outside air to enter the furnace cavity through these gaps and aid combustion of the gas. The flow trajectories of air, fuel gas, and exhaust gas within the furnace cavity are guided by both negative pressure and the internal structure. For specific flow directions, please refer to [reference needed]. Figure 3 The direction of the dashed arrow in the image is indicated.

[0019] It is important to note that the negative pressure furnace 1000 in this embodiment is an advanced induced draft energy-saving stove. Compared to traditional gas stoves that rely on positive pressure forced draft, the negative pressure furnace 1000 in this embodiment generates negative pressure throughout the flow channel through a fan 500 installed at the end. This design allows the gas and air to be fully mixed by being "drawn" into the combustion heat exchanger 200. The arc-shaped fins 230 significantly increase the heated surface area of ​​the pot bottom, and the arc structure of the fins guides the flame and high-temperature flue gas to form a swirling flow, extending the residence time of the high-temperature gas in the furnace. This allows for the full absorption of the heat released from gas combustion and efficient transfer of heat to the pot body 100. The suction generated by the fan 500 forces fresh external air into the furnace on demand and in a measured manner to mix with the gas. This forced convection mechanism results in a faster airflow velocity, allowing the exhaust gas produced by combustion to be quickly carried away from the flame surface, effectively reducing the thermal resistance of the combustion reaction zone. This allows the fresh gas mixture to quickly fill the reaction zone, promoting more complete combustion. This not only increases the combustion temperature, but also ensures extremely complete combustion due to the ample and uniform oxygen supply, resulting in very low emissions of harmful gases such as carbon monoxide.

[0020] Reference Figure 3 and Figure 8As shown, to further optimize airflow organization, in some preferred embodiments, the combustion heat exchanger 200 also includes a guide plate 240. The guide plate 240 is a horizontally arranged circular plate structure located between the arc-shaped fins 230 and the base plate 220, clearly dividing the inner cavity of the combustion heat exchanger 200 vertically into an upper cavity 244 (i.e., the combustion heat exchange zone) and a lower cavity 245 (i.e., the air inlet and collection zone). Specifically, the top surface of the guide plate 240 is welded and fixed to the bottom surface of the arc-shaped fins 230, serving the dual purpose of supporting the fins and separating the cavities. At this time, the arc-shaped fins 230 are mainly located in the upper cavity 244, directly contacting the flame. A guide nozzle 241 protruding upwards is provided at the center of the guide plate 240. This guide nozzle 241 passes through the lower cavity 245, directly connecting the gas inlet 221 of the base plate 220 and the upper cavity 244, ensuring that the gas is directly injected into the central combustion zone of the upper cavity 244. At the edge of the guide plate 240, several through holes 243 or annular slits 251 are provided to connect the upper cavity 244 and the lower cavity 245. The working flow is as follows: the gas enters the upper cavity 244 through the guide nozzle 241 for combustion. The resulting high-temperature flue gas, under negative pressure, must first pass over the arc-shaped fins 230 within the upper cavity 244, flow towards the edge, and then enter the lower cavity 245 through the through holes 243 at the edge of the guide plate 240, finally converging at the exhaust outlet 222. With this configuration, the guide plate 240 effectively forces the gas and flame to radiate outwards from the center. Combined with the suction of the fan 500, the flame no longer scatters after vertically impacting the bottom of the pot like in traditional stoves, but is instead tightly adsorbed and "attached" to the bottom surface and fin surface of the pot body 100. This fluid dynamic "wall adhesion effect" greatly increases the contact area and contact time between the flame and the bottom of the pot, significantly improving heat transfer efficiency.

[0021] Reference Figure 3 and Figure 8 As shown, in some further embodiments, the guide plate 240 is not a purely planar structure, but has an inclined section 242, causing part of the structure of the guide plate 240 to have an upward-curving shape. Specifically, the height of the guide plate 240 gradually increases from its center to the surrounding edges, and the inclined section 242 can be understood as an inverted shallow conical section or a flared structure. The purpose of this design is mainly to guide the flame ejected from the central air guide nozzle to spread outwards along the slope towards the periphery of the guide plate 240. This geometric guidance, combined with negative pressure suction, allows the flame to fit against the bottom surface of the pot body 100 and its arc-shaped fins 230 at a better angle, avoiding the problem of localized overheating of the flame in the center while the edge temperature is insufficient, thus improving the uniformity of heating.

[0022] Reference Figure 3 and Figure 6As shown, considering manufacturing processes and ease of installation, in some embodiments, the outer plate 210 is designed as a split structure, including an upper plate 212 and a lower plate 213. Both the upper plate 212 and the lower plate 213 are annular plates of the same diameter, with the upper plate 212 positioned above the lower plate 213. The edge of the guide plate 240 is clamped and welded between the upper plate 212 and the lower plate 213. This arrangement allows for easier assembly during production by first welding the upper plate 212 to the fins and the bottom of the pot, then installing the guide plate 240, and finally welding the lower plate 213 and the bottom plate 220. This significantly reduces welding difficulty and facilitates the positioning and installation of the guide plate 240.

[0023] Reference Figure 3 , Figure 4 and Figure 6 As shown, to construct a more complex and efficient flue gas return path, in some embodiments, an inner shroud 250 is added inside the combustion heat exchanger 200. The inner shroud 250 is an annular plate with a diameter smaller than that of the outer shroud 210, located on the inner circumference of the outer shroud 210. The lower end face of the inner shroud 250 is welded and sealed to the upper surface of the guide plate 240, while the upper end face of the inner shroud 250 is spot-welded to the bottom surface of the pot body 100, or a predetermined gap is left. Crucially, a specially designed gap 251 exists between the inner shroud 250 and the bottom surface of the pot body 100. This gap 251 is located at the top of the inner shroud 250, allowing fluid to pass through. Simultaneously, the through hole 243 on the guide plate 240 is located within the annular region between the inner shroud 250 and the outer shroud 210. This design allows the gas to burn and rise in the central area surrounded by the inner shroud 250. The heat flow is obstructed by the inner shroud 250 and must instead "stick" to the bottom of the pot, passing through the top gap 251, over the inner shroud 250, and into the interlayer between the inner shroud 250 and the outer shroud 210. Then, it flows downwards through the through-hole 243 on the guide plate 240 into the lower cavity 245. This design forcibly restricts the gas flow to an upward angle and close to the bottom of the pot, greatly extending the flow path of the high-temperature flue gas and ensuring sufficient heat release. Furthermore, the narrow width of the gap 251 further enhances the negative pressure effect.

[0024] Reference Figure 3 , Figure 5 and Figure 10As shown, to further improve thermal efficiency and stabilize combustion, in some embodiments, multiple heat storage bricks 260 are specially arranged between the burner 400 and the gas inlet 221. The heat storage bricks 260 are preferably made of porous ceramic materials such as high-alumina refractory materials, cordierite ceramics, or silicon carbide. The heat storage bricks 260 are arranged in a circle or a specific square shape around the outer periphery of the gas inlet 221. Their working principle is as follows: the initial flame generated by gas combustion first heats these heat storage bricks 260, making them glow red-hot. Once the heat storage bricks 260 reach a high-temperature, red-hot state, they become a constant, high-intensity infrared radiation heat source. The heat storage bricks 260 can emit high-intensity infrared radiation towards the bottom of the pot. This radiative heat transfer differs from the convective heat transfer of ordinary flames; it is unaffected by airflow fluctuations and has strong penetrating power. Even if the flame itself flickers momentarily due to wind pressure fluctuations, the enormous heat stored in the red-hot heat storage brick 260 can continuously and stably radiate heat energy to the bottom of the pot, acting as a "pressure stabilizer" and "efficiency enhancer".

[0025] Reference Figure 3 , Figure 5 and Figure 10 As shown, in terms of structural fixation, in some embodiments, the heat storage brick 260 is installed on the bottom of the pot body 100 using a dedicated mounting bracket 270. The mounting bracket 270 has a U-shaped or frame structure, and its interior is provided with U-shaped grooves 271 or slots for embedding and placing the heat storage brick 260, ensuring that the brick does not shift. The mounting bracket 270 is installed on the bottom of the base plate 220 by high-strength bolts passing through it, while the burner 400 is directly installed on the bottom of the mounting bracket 270 and connected to the studs on the bottom of the mounting bracket 270 by nuts. This modular installation method not only makes the installation process more convenient, but also facilitates future maintenance and replacement of the heat storage brick 260 or the burner 400.

[0026] Reference Figure 3 , Figure 5 and Figure 9As shown, regarding the exhaust gas treatment section, the exhaust gas waste heat exchanger 300 includes a shell 310 and heat exchange fins 320. The shell 310 is internally divided by a partition into a non-communicating exhaust gas chamber 311 and a cooling water chamber 312, ensuring absolute isolation between the gas and water paths. The outer peripheral wall of the shell 310 is provided with an inlet 313 and an outlet 314 communicating with the cooling water chamber 312, and an inlet 315 and an outlet 316 communicating with the exhaust gas chamber 311. The inlet 315 is connected to the exhaust gas outlet 222 on the base plate 220 of the combustion heat exchanger 200 via a pipe, while the outlet 316 is connected to the air inlet of the negative pressure fan 500. The heat exchange fins 320 adopt an intercalation design, with part of their structure extending into the exhaust gas chamber 311 to increase the exhaust gas contact area; another part of their structure extends into the cooling water chamber 312 to increase the water contact area. Thus, the heat exchange fins 320 act as a thermal bridge, rapidly transferring the heat carried by the exhaust gas in the exhaust gas chamber 311 to the cooling water chamber 312. During operation, cold water is continuously supplied to the cooling water chamber 312. The heat exchange fins 320 efficiently transfer the heat from the exhaust gas to the cooling water, significantly reducing the temperature of the discharged exhaust gas, typically to a low level. This protects the fan 500 and reduces thermal pollution to the environment. The heated cooling water can then be used in an insulated container for washing dishes, cleaning, or cooking in the kitchen, thus recovering waste heat from the exhaust gas and truly achieving energy conservation and environmental protection.

[0027] Reference Figure 3 , Figure 5 and Figure 9 As shown, in a specific manufacturing embodiment, the housing 310 can be divided into an upper housing 317 and a lower housing 318, and the heat exchange fins 320 are designed as a straight fin array. The heat exchange fins 320 pass vertically through and are welded to an intermediate plate 330, which divides the fins into an upper fin portion 321 and a lower fin portion 322. The plate 330 is welded between the upper housing 317 and the lower housing 318 as a separator, so that the upper fins 321 are immersed in the water flow of the cooling water chamber 312, and the lower fins 322 are exposed to the airflow of the exhaust gas chamber 311. This sandwich-like structural arrangement greatly simplifies the assembly process of the exhaust gas waste heat exchanger 300 and ensures sealing performance.

[0028] Reference Figure 3 As shown, to maximize the utilization of thermal energy, in some embodiments, the upper end face of the shell 310 of the waste gas heat exchanger 300 is designed to directly contact or closely adhere to the bottom plate 220 of the combustion heat exchanger 200. In this way, the shell 310 can not only exchange heat through its internal fluids but also directly absorb heat dissipated from the bottom plate 220 (i.e., the high-temperature waste gas accumulation area in the lower cavity 245) through contact conduction. Furthermore, a thermally conductive structure (such as thermal grease, a metal heat spreader, or a flexible graphite pad) can be provided between the shell 310 and the bottom plate 220 to further enhance contact heat conduction efficiency and reduce heat loss.

[0029] Finally, refer to Figure 3 and Figure 5 As shown, to ensure a tight seal, the base plate 220 of the combustion heat exchanger 200 has a downward-extending metal connector 223 at the exhaust gas outlet 222, while the inlet 315 of the waste heat exchanger 300 is correspondingly upward-facing. During assembly, the connector 223 is inserted into the inlet 315 and fixed and sealed by welding, flange connection, or high-temperature resistant sealant. This design not only facilitates quick alignment and assembly of the connector 223 and the inlet 315 but also effectively prevents leakage of high-temperature exhaust gas during transmission, ensuring the airtightness and stability of the negative pressure system.

[0030] The embodiments of the present invention have been described in detail above, and examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described above with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] In the description of this utility model, it should be understood that the orientation descriptions, such as up, down, front, back, inside, outside, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this utility model.

[0032] In the description of this utility model, the use of "first" and "second" is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features or the order of the technical features.

[0033] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0034] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model, and not to limit it. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present utility model.

Claims

1. A negative pressure furnace, characterized in that, include: The pot body; Burner; A combustion heat exchanger is arranged at the bottom of the pot body. The combustion heat exchanger includes an outer plate, a bottom plate, and multiple arc-shaped fins. The outer plate is located below the pot body, and its upper end is welded to the bottom surface of the pot body. The bottom plate is welded to the lower end surface of the outer plate. The bottom plate is provided with a gas inlet and an exhaust outlet. The multiple arc-shaped fins are arranged at intervals along the circumference of the pot body. The arc-shaped fins are arranged on the inner circumference of the outer plate. The outer plate, the bottom plate, and the pot body form an inner cavity. A waste gas heat exchanger includes a shell and heat exchange fins. The shell has a waste gas chamber and a cooling water chamber that are not interconnected. The outer peripheral wall of the shell has an inlet and an outlet that communicate with the cooling water chamber. The shell also has an air inlet and an air outlet that communicate with the waste gas chamber. Part of the structure of the heat exchange fins is located inside the waste gas chamber, and part of the structure of the heat exchange fins is located inside the cooling water chamber. A fan, the air inlet of which is connected to the air outlet.

2. The negative pressure furnace according to claim 1, characterized in that, The combustion heat exchanger also includes a guide plate, which is located between the arc-shaped fins and the guide plate. The top surface of the guide plate is welded and fixed to the bottom surface of the arc-shaped fins. The guide plate divides the inner cavity into an upper cavity and a lower cavity. The arc-shaped fins are located in the upper cavity. A guide nozzle is provided at the center of the guide plate, which connects the gas inlet and the upper cavity. A through hole is provided at the edge of the guide plate to connect the upper cavity and the lower cavity.

3. The negative pressure furnace according to claim 2, characterized in that, The guide plate has an inclined section for guiding the flame flowing upward from the guide nozzle to spread diagonally upward to the periphery of the guide plate.

4. The negative pressure furnace according to claim 2, characterized in that, The outer plate includes an upper section plate and a lower section plate, with the upper section plate located above the lower section plate, and the guide plate welded between the upper section plate and the lower section plate.

5. The negative pressure furnace according to claim 2, characterized in that, The combustion heat exchanger also includes an inner shroud, which is an annular plate located on the inner periphery of the outer shroud. The lower end face of the inner shroud is welded and sealed to the guide plate, and the upper end face of the inner shroud is spot-welded to the bottom surface of the pot body. There is a gap between the inner shroud and the pot body.

6. The negative pressure furnace according to claim 1, characterized in that, The housing includes an upper shell and a lower shell. The heat exchange fins are welded onto a flat plate. The heat exchange fins include upper fins and lower fins. The upper fins are welded to the upper end face of the flat plate, and the lower fins are welded to the lower end face of the flat plate. The flat plate is welded between the upper shell and the lower shell. The upper fins are located in the cooling water chamber, and the lower fins are located in the exhaust gas chamber.

7. The negative pressure furnace according to any one of claims 1 to 6, characterized in that, A heat storage brick is provided between the burner and the gas inlet, and the heat storage brick surrounds the outer periphery of the gas inlet.

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