Jet type negative pressure reverse combustion furnace

Abstract

The jet type negative pressure reverse combustion furnace comprises a fuel tank, a furnace bar, a combustion chamber, a combustion-supporting tuyere, a furnace mouth and a fire outlet, the fuel tank is communicated with the combustion chamber, the combustion-supporting tuyere is connected with an air gathering box through a combustion-supporting air pipe, an outer fire pipe is arranged on the air gathering box, an inner fire pipe is concentrically installed in the outer fire pipe, and the inner fire pipe is communicated with the combustion chamber; the inner fire tube and the outer fire tube form a sleeve structure, a jet flow channel is formed between the inner fire tube and the outer fire tube, the jet flow channel is communicated with the air gathering box, the fan feeds air into the air gathering box through the combustion-supporting air tube and sprays the air out of the jet flow channel, and negative pressure is generated in the inner fire tube while jet flow is sprayed out. And the furnace mouth negative pressure air door is opened by the negative pressure synchronously generated in the combustion chamber. According to the reverse combustion furnace, positive-pressure air inlet is carried out in an air blowing mode, then high-pressure air is generated through the jet flow channel to guide negative pressure to be generated in the furnace body, two-time combustion is achieved, combustion is more sufficient, heat efficiency is improved, and meanwhile harmful substances (such as dioxin) can be decomposed easily, and pollutant emission is reduced.

Description

Technical Field

[0001] This invention relates to the field of reverse combustion furnace technology, and specifically to a jet-type negative pressure reverse combustion furnace. Background Technology

[0002] A reverse combustion furnace, also known as a bottom-up combustion furnace, is a highly efficient and environmentally friendly solid fuel (such as coal, wood, and biomass pellets) combustion device. Its core feature is bottom-up combustion. Because it achieves secondary combustion, the chemical energy of the fuel is utilized to a great extent, resulting in more fuel savings and higher thermal efficiency compared to traditional stoves.

[0003] CN105570933A discloses a biomass heating stove, including a stove body and a grate. The grate divides the stove body into an upper stove body and a lower stove body. The upper stove body includes a feed inlet, a packing chamber, and an ignition port. The feed inlet is located on the upper wall of the upper stove body, and the ignition port is located on the side of the upper stove body near the bottom. The lower stove body includes an ignition port, an ash chamber, an ash removal port, and an air inlet pipe. The ash removal port is closable. The air inlet of the air inlet pipe is located below the grate, close to the grate, and the other end passes through the stove wall to communicate with the outside air of the stove body. Although this patent also discloses a negative pressure reverse combustion stove, its negative pressure is caused by the attraction generated by the flow of flue gas in the exhaust system, which is a induced negative pressure, and is quite different from the jet negative pressure mechanism claimed in this invention.

[0004] CN203131799U discloses an automatic control biomass reverse combustion furnace. During combustion, the ash automatically falls into the ash collection chamber, ensuring sufficient oxygen supply to the oxidation-reduction zone. Utilizing the principle of rising hot air, part of the rising hot air preheats the fuel, evaporates excess moisture, and rapidly raises the temperature of the coke to its ignition point, ensuring smooth combustion, complete fuel combustion, and high thermal efficiency.

[0005] Existing reverse combustion furnaces all use induced draft negative pressure for combustion assistance, which has the following problems:

[0006] 1. If the natural flow of smoke from the exhaust system is used to generate gravity, the intake power is weak, making it difficult to increase the firepower intensity and the control precision of the firepower is insufficient.

[0007] 2. If forced power is used, such as an induced draft fan driving the flow of flue gas in the exhaust system to generate suction, then the requirements for the induced draft fan are higher. If the motor and fan blades are integrated, the motor is easily burned by the high-temperature flue gas in the exhaust system; if the motor and fan blades are separate, the induced draft device is more complex, more expensive, and more difficult to maintain.

[0008] 3. Although it can also carry out two combustion processes, there is no cumulative effect in the combustion temperature, making it difficult to form high-temperature flue gas. High-temperature flue gas flows at a relatively high speed, and some large molecular harmful substances (such as dioxins) do not have enough high temperature and time to decompose.

[0009] Therefore, a jet negative pressure reverse combustion furnace is needed to solve the above problems. Summary of the Invention

[0010] To address the aforementioned problems, this invention provides a jet-type negative pressure reverse combustion furnace, which abandons the traditional reverse combustion furnace method of using induced draft to generate negative pressure for combustion. Instead, it adopts a "jet negative pressure" mode, which is applicable to messy and loose natural fuels, has strong fuel adaptability, and the flame and flue gas generated in the combustion chamber are drawn into the inner fire tube by the negative pressure generated by the jet. Here, they mix with sufficient oxygen entering from the jet channel for efficient and thorough secondary combustion. This secondary combustion can generate a high-temperature superposition effect in the flue gas, increasing the flue gas temperature and promoting the decomposition of harmful substances such as dioxins. In addition, while the jet generates negative pressure to induce draft at the combustion point in the furnace for primary combustion, secondary positive pressure combustion occurs at the jet outlet. Ultimately, the high-temperature flue gas at the outlet is rushed out in the form of positive pressure. The outgoing high-temperature flue gas is affected by the resistance of the heat dissipation structure, and the flue gas velocity is slowed down. On the one hand, this promotes the improvement of heat exchange efficiency, and on the other hand, it prolongs the residence time of the high-temperature flue gas, further promoting the decomposition of harmful substances such as dioxins and improving combustion efficiency.

[0011] Specifically, the present invention is implemented as follows:

[0012] A jet-type negative pressure reverse combustion furnace includes: a fuel tank, a grate, a combustion chamber, a combustion air inlet, a furnace opening, and a fire outlet. The fuel tank is connected to the combustion chamber. The combustion air inlet is connected to a concentrating air box through a combustion air pipe. An outer fire pipe is provided on the concentrating air box, and an inner fire pipe is concentrically installed inside the outer fire pipe. The inner fire pipe is connected to the combustion chamber.

[0013] The inner fire tube and the outer fire tube form a sleeve structure, and a jet channel is formed between them. The jet channel is connected to the air collection box. The fan sends air into the air collection box through the combustion air inlet and the combustion air duct, and sprays it out from the jet channel, generating negative pressure in the inner fire tube.

[0014] The positive pressure combustion air blown out by the jet channel causes secondary combustion of the primary combustion flue gas drawn from the inner fire tube during the process from the jet port to the fire outlet. The secondary combustion flue gas is then ejected from the fire outlet from the outer fire tube under positive pressure.

[0015] The furnace opening is equipped with a furnace opening negative pressure damper, which is configured to open towards the combustion chamber. When a negative pressure is generated inside the inner fire tube, the negative pressure generated simultaneously in the combustion chamber will draw the furnace opening negative pressure damper open.

[0016] Furthermore, below the combustion chamber is an ash bin, which is equipped with a cleaning port and a negative pressure damper. The negative pressure damper is configured to open to one side of the ash bin. When a negative pressure is generated inside the inner fire tube, the negative pressure generated simultaneously in the ash bin will draw the negative pressure damper of the cleaning port open.

[0017] Furthermore, a return steam pipe is provided on the top of the fuel tank, which is connected to the combustion chamber and is used to send the water vapor or flue gas accumulated on the top of the fuel tank into the combustion chamber.

[0018] Furthermore, the combustion air duct passes through the ash bin and is located below the grate.

[0019] Furthermore, a refractory support is provided at the bottom of the fuel tank, and the lower part of the refractory support is the feeding port. The grate is located directly below the feeding port, and the size of the feeding port is smaller than the size of the grate.

[0020] Furthermore, a fuel tank cover is provided on the top of the fuel tank.

[0021] Furthermore, the orientation of the flame outlet can be set as needed, not limited to upward or horizontal arrangement as shown in the figure, but also to left, right, or downward.

[0022] Working principle:

[0023] After the fuel tank 1 is filled with fuel, the fuel tank cap 11 is closed, and the fuel is ignited. The air blown by the blower 31 enters the air-collecting box 4 through the combustion air duct 3. The air in the air-collecting box 4 reaches saturated positive pressure and enters the jet channel 41 evenly and forcefully. After the high-pressure air from the jet channel 41 enters the outer burner tube 5, it generates a Venturi effect at the inlet of the inner burner tube 6 (a low pressure is generated near a high-speed flowing fluid, and this low pressure will cause an adsorption effect). The high-pressure air will cause a negative pressure to be generated in the inner burner tube 6. The drag force of the negative pressure It extends to places such as combustion chamber 2, ash bin 8, furnace opening 7, and ash removal port. Intentionally or unintentionally, air enters these places, and outside oxygen-containing air enters to participate in the combustion of fuel in grate 21 and fuel box 1. The flame and flue gas generated in combustion chamber 2 will reach the inner fire tube 6 through the negative pressure path and rush out from the pipe opening of the inner fire tube 6. It will undergo secondary combustion with the outside oxygen-containing air blown out by jet channel 41 in outer fire tube 5. The flue gas from the secondary combustion will rush out of the outer fire tube from the fire outlet in a positive pressure manner.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) The reverse combustion furnace is suitable for various solid combustibles in natural form, mainly biomass, including commonly seen branches and straw, wood scraps, various combustible fiber products, rubber products, and various waste combustibles. These combustible wastes do not need to be specially shaped or crushed into a certain standard size. They can be put into the feed box through simple processing, and have strong applicability.

[0026] (2) The combustibles in the fuel tank gradually sink by gravity, without the need for a special feeding and feeding device. The sleeve structure (outer fire tube + inner fire tube) shares the fuel tank and combustion chamber, which simplifies the overall structure, reduces manufacturing difficulty and cost, and makes maintenance more convenient.

[0027] (3) By using the method of induced combustion, the negative pressure is guided by the high-pressure air generated by the jet channel, which realizes secondary high-temperature superposition combustion, making the combustion more complete and improving the thermal efficiency. At the same time, it helps to decompose harmful substances (such as dioxins) and reduce pollutant emissions. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the jet-type negative pressure reverse combustion furnace in Example 1;

[0029] Figure 2 This is a side view of the jet-type negative pressure reverse combustion furnace in Example 1;

[0030] Figure 3 for Figure 2 Schematic diagram of the AA section;

[0031] Figure 4 This is a cross-sectional view of the nozzle in Example 1;

[0032] Figure 5 This is a cross-sectional view of the jet-type negative pressure reverse combustion furnace in Example 2.

[0033] Figure label:

[0034] 1-Fuel tank; 11-Fuel tank cover; 12-Refractory support; 13-Fire outlet; 2-Combustion chamber; 21-Grate; 3-Combustion air duct; 31-Blower; 4-Air collection box; 41-Jet channel; 5-Outer fire tube; 6-Inner fire tube; 7-Furnace opening; 71-Furnace opening negative pressure damper; 8-Ash bin; 81-Ash cleaning port negative pressure damper; 9-Steam return pipe. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0036] Example 1

[0037] like Figure 1-4As shown, this embodiment provides a jet-type negative pressure reverse combustion furnace, including: a fuel tank 1, a grate 21, a combustion chamber 2, a combustion air inlet, a furnace opening, and a fire outlet 13. The fuel tank 1 is a sealed structure with an openable and closable fuel tank cover 11 at the top and a refractory support 12 at the bottom. The bottom of the refractory support 12 is a feeding port, and the combustion chamber 2 is below the feeding port. The grate 21 is located inside the combustion chamber 2 and directly below the feeding port. The size of the feeding port is smaller than the size of the grate 21 so that the fuel falls onto the grate 21 and burns above and below it. As combustion proceeds, the combustibles in the fuel tank 1 gradually and automatically sink under the action of gravity. The fuel tank and the combustion chamber share almost the same space, eliminating the need for a special feeding and discharging device, which effectively simplifies the equipment.

[0038] One side of the combustion chamber 2 is a furnace opening 7, which is used for ignition and air intake. A furnace opening negative pressure damper 71 is installed on the furnace opening 7, which is hinged to the furnace opening 7 and opens towards the combustion chamber 2. The lower part of the combustion chamber 2 is an ash and slag bin 8, which is equipped with a ash cleaning port negative pressure damper 81, which is hinged to the ash and slag bin 8 and opens towards the ash and slag bin 8.

[0039] On the other side of combustion chamber 2, an inner fire tube 6 is connected, forming a primary fire outlet with the jet nozzle. A combustion-supporting air duct 3 is installed below the grate 21, running between the ash bin 8 and combustion chamber 2. One end is connected to a blower 31, and the other end to an air-gathering box 4. An upward-facing outer fire tube 5 is installed at the top of the air-gathering box 4. The outer fire tube 5 and the inner fire tube 6 are installed concentrically, forming a sleeve structure. A jet channel 41 is formed between them, communicating with the air-gathering box 4. The blower 31 delivers air into the air-gathering box 4 at positive pressure through the combustion-supporting air duct 3, and ejects it from the jet channel 41 at positive pressure. The high-pressure air generates a Venturi effect at the inner fire tube nozzle (a low-pressure environment is generated near a high-speed flowing fluid). This low pressure (which generates an adsorption effect) causes the high-pressure air to create a negative pressure inside the inner fire tube 6. The drag force of this negative pressure extends to the combustion chamber 2, ash bin 8, furnace opening 7, and ash removal port. Intentionally or unintentionally, air enters these areas, allowing oxygen-containing air from the outside to participate in the combustion of fuel in the grate 21 and fuel tank 1. The flames and flue gas generated in the combustion chamber 2 travel along the path of the negative pressure to the inner fire tube 6 and exit from the inner fire tube opening. There, they undergo secondary combustion (local temperatures exceeding 900℃) with the oxygen-containing air blown out by the jet channel 41 in the outer fire tube 5, resulting in more complete combustion, improved thermal efficiency, and the decomposition of harmful substances (such as dioxins), reducing pollutant emissions. The opening of the furnace opening negative pressure damper 71 is related to the negative pressure caused by the jet channel 41. The greater the airflow from the blower 31, the greater the negative pressure, and the wider the furnace opening negative pressure damper 71 opens, allowing more air to enter, thus controlling the overall firepower of the system.

[0040] Because the furnace is always under negative pressure, there is no risk of flame ejection or backfire, making it highly safe.

[0041] The combustion air duct 3 is installed below the grate 21. The backfire flame and high-temperature flue gas will heat the combustion air duct 3, thereby preheating the air supplied by the blower 3, which helps the secondary combustion that occurs at the outlet of the outer fire tube 5.

[0042] A return steam pipe 9 is installed at the top of the fuel tank 1. The return steam pipe 9 is connected to the combustion chamber 2. Since the fuel layer of the fuel tank 1 is relatively thick, especially after each feeding, the negative pressure during the operation of the reverse combustion furnace makes it difficult to drag the water vapor and flue gas generated by heat conduction in the fuel layer downward. These water vapor and flue gas will accumulate at the top of the fuel tank 1. If too much accumulates, it will overflow from the gap of the fuel tank cover 11. The function of the return steam pipe 9 is to avoid this situation and to draw the water vapor and flue gas that have escaped to the top of the fuel tank 1 back to the combustion position.

[0043] Example 2

[0044] In this embodiment, based on Embodiment 1, the outlets of the inner fire tube 6 and the outer fire tube 5 are changed to a horizontal arrangement, and the position of the outlet can be selected according to actual usage requirements. Similarly, based on Embodiment 1, the circular structure of the inner fire tube 6 and the outer fire tube 5 can also be changed to a square structure, including the circular structure of the fuel tank, which can also be changed to a square or other suitable shape structure according to actual usage requirements.

[0045] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A jet-type negative pressure reverse combustion furnace, comprising: The fuel tank (1), grate (21), combustion chamber (2), combustion air inlet, furnace opening (7), and fire outlet (13), wherein the fuel tank (1) is connected to the combustion chamber (2), characterized in that, The combustion air outlet is connected to the air collection box (4) through the combustion air pipe (3). An outer fire pipe (5) is provided on the air collection box (4). An inner fire pipe (6) is installed concentrically inside the outer fire pipe (5). The inner fire pipe (6) is connected to the combustion chamber (2). The inner fire tube (6) and the outer fire tube (5) form a sleeve structure, and a jet channel (41) is formed between them. The jet channel (41) is connected to the air collection box (4). The fan (31) sends air into the air collection box (4) through the combustion air inlet and the combustion air pipe (3), and sprays it out from the jet channel (41), causing negative pressure to be generated in the inner fire tube (6). The furnace opening (7) is provided with a furnace opening negative pressure damper (71). The furnace opening negative pressure damper (71) is configured to open towards the combustion chamber (2). When a negative pressure is generated in the inner fire tube (6), the negative pressure generated synchronously in the combustion chamber (2) will draw the furnace opening negative pressure damper (71) open.

2. The jet-type negative pressure reverse combustion furnace as described in claim 1, characterized in that, Below the combustion chamber (2) is an ash bin (8), which is equipped with an ash cleaning port. The ash cleaning port is equipped with a ash cleaning port negative pressure damper (81). The ash cleaning port negative pressure damper (81) is configured to open to one side of the ash bin (8). When a negative pressure is generated in the inner fire tube (6), the negative pressure generated simultaneously in the ash bin (8) will draw the ash cleaning port negative pressure damper (81) open.

3. The jet-type negative pressure reverse combustion furnace as described in claim 1, characterized in that, The fuel tank (1) is provided with a steam return pipe (9) at the top, which is connected to the combustion chamber (2) and is used to send the water vapor or flue gas gathered at the top of the fuel tank (1) into the combustion chamber (2).

4. The jet-type negative pressure reverse combustion furnace as described in claim 1, characterized in that, The combustion air duct (3) passes through the ash bin (8) and is located below the grate (21).

5. The jet-type negative pressure reverse combustion furnace as described in claim 1, characterized in that, The fuel tank (1) is provided with a refractory support platform (12) at the bottom. The lower part of the refractory support platform (12) is the feeding port. The grate (21) is located directly below the feeding port. The size of the feeding port is smaller than the size of the grate (21).

6. The jet-type negative pressure reverse combustion furnace as described in claim 1, characterized in that, The fuel tank (1) is provided with a fuel tank cover (11) on top.

7. The jet-type negative pressure reverse combustion furnace as described in claim 1, characterized in that, The fire outlet (13) is arranged facing left, right, up or down.

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