Head exhaust pipe heating furnace

Abstract

The present invention provides a head exhaust pipe type heating furnace, wherein a furnace pipe is installed in the furnace; a burner is installed at the head, i.e., the bottom, of the furnace, and a special-shaped partition is provided inside the burner; the internal cavity of the special-shaped partition is an air channel, and the external cavity is a flue gas channel; the special-shaped partition, flue gas channel, and air channel constitute an air preheater; one end of the air channel is connected to the combustion-supporting blower through a connecting pipe, and the other end leads to the furnace; one end of the flue gas channel is connected to the induced draft fan through a connecting pipe, and the other end leads to the furnace; a fuel spray gun is installed inside the burner, and one end of the fuel spray gun is connected to the fuel regulating valve through a connecting pipe, and the other end leads to the furnace. The present invention adopts a head exhaust structure to reduce the weight of the heating furnace; high-temperature flue gas forms a backflow in the furnace, which is conducive to enhancing combustion, heat transfer, and temperature uniformity; flue gas is discharged from the head, and when flue gas purification equipment needs to be installed, it can be implemented on the head ground without changing the furnace body load-bearing structure.

Description

Technical Field

[0001] The present invention relates to the technical field of tubular heating furnaces, and in particular to a head exhaust tubular heating furnace. Background Art

[0002] Tubular heating furnaces are widely used in petrochemical and coal chemical industries for material process heating.

[0003] The tubular heating furnace has a heated fluid inside the tube and a heat source outside the tube. It is divided into two categories: fuel combustion flame heating and electric heating.

[0004] For tubular heating furnaces heated by fuel combustion flames, fuel and oxidant (usually air) are supplied by a burner installed at the head of the heating furnace, which burns in the furnace to produce a high-temperature flame. The heat of the flame is transferred to the fluid material in the furnace tube through radiation, convection and heat conduction, so that the material reaches the temperature required by the process and is used for the next process. The flue gas cooled by combustion and heat transfer is discharged from the tail end of the heating furnace.

[0005] The typical tubular heating furnace is a vertical structure, such as Figure 3 The burner is usually installed at the bottom of the heating furnace. The fuel and combustion air are mixed and burned in the furnace through the burner nozzle. The combustion flue gas transfers heat to the furnace tubes by radiation and convection in the furnace and convection section, heating the fluid in the furnace tubes. After cooling, it is discharged to the atmosphere through the chimney from the top (tail) of the heating furnace.

[0006] In order to save energy, an air preheater is often installed on the upper (tail) flue of a tubular heating furnace with a higher exhaust temperature. The waste heat in the flue gas is used to heat the combustion air, and the heated combustion air is sent back to the burner to enter the furnace for combustion, replacing part of the heat released by fuel combustion, thereby reducing fuel consumption and saving energy and reducing costs.

[0007] However, the disadvantages of the tail exhaust method are:

[0008] 1. When the flue gas passes through the tail convection section and air preheater, the heat transfer efficiency is low due to the low flue gas temperature and large surface area of the equipment, resulting in low overall efficiency of the heating furnace;

[0009] 2. The convection section and air preheater are large and heavy, which leads to high requirements for the load-bearing structure of the lower part of the heating furnace and increases the cost. At the same time, the upper convection section and air preheater are inconvenient to repair and replace;

[0010] 3. The flue gas flows vertically upward, which is not conducive to adjusting the temperature distribution in the furnace to achieve uniform heat transfer;

[0011] 4. The flue gas is discharged straight upwards and the flue is at a high altitude, which is not conducive to the installation of tail flue gas treatment environmental protection equipment for reducing sulfur oxides and nitrogen oxides. Summary of the Invention

[0012] In response to the above technical problems, the present invention proposes a tubular heating furnace structure with head smoke exhaust, which combines the tail air preheater and the head burner into one, eliminates the tail (upper) inefficient convection section and air preheater, and the fuel and combustion air enter the furnace through the head (lower) burner for mixed combustion. The completely burned flue gas transfers heat to the material in the furnace tube through high-temperature and high-efficiency radiation heat transfer, and then flows back in the opposite direction, and transfers the waste heat of the flue gas to the combustion air through the air preheater built into the head burner. The cooled flue gas is finally drawn into a centralized or independent flue by an induced draft fan from the flue gas outlet of the head burner of the heating furnace for discharge.

[0013] The specific technical solutions are:

[0014] Head exhaust pipe type heating furnace, including furnace, furnace tube, burner, combustion fan, induced draft fan, fuel regulating valve and shut-off valve;

[0015] A furnace tube is installed in the furnace chamber;

[0016] The burner is installed at the head or bottom of the furnace, and a special-shaped partition is installed inside the burner. The cavity inside the special-shaped partition is the air channel, and the cavity outside is the flue gas channel. The special-shaped partition, flue gas channel and air channel constitute the air preheater. One end of the air channel is connected to the combustion-supporting fan through a connecting pipe, and the other end leads to the furnace. One end of the flue gas channel is connected to the induced draft fan through a connecting pipe, and the other end leads to the furnace.

[0017] A fuel spray gun is installed inside the burner. One end of the fuel spray gun is connected to the fuel regulating valve through a connecting pipe, and the other end leads to the furnace.

[0018] The head (lower) smoke exhaust tube type heating furnace is equipped with a burner with its own heat exchanger. The head (lower) smoke exhaust structure can completely remove the convection section, air preheater and chimney at the tail (upper) of the heating furnace in the existing technology, greatly reducing the weight of the heating furnace; the high-temperature flue gas forms a backflow in the furnace, which is conducive to enhancing combustion, heat transfer and temperature uniformity; the flue gas is discharged from the head (lower part), and when it is necessary to install flue gas purification equipment, it can be achieved on the ground of the head without changing the load-bearing structure of the furnace body.

[0019] Alternatively, the present invention also proposes a head-to-tail combined smoke exhaust tube furnace structure, which combines the tail air preheater and the head burner into one, eliminates the tail (upper) inefficient convection section and air preheater, and the fuel and combustion air enter the furnace through the head (lower) burner for mixed combustion. The completely burned flue gas transfers heat to the material in the furnace tube through high-temperature and high-efficiency radiation heat transfer, and then flows back in the opposite direction, and transfers the waste heat of the flue gas to the combustion air through the air preheater built into the head burner. The cooled flue gas is finally drawn by the induced draft fan from the flue gas outlet of the head burner of the heating furnace to the chimney at the tail (upper) of the heating furnace for discharge.

[0020] According to a further technical solution, a chimney is installed at the upper portion of the furnace tail, and a flue valve plate is provided between the chimney and the furnace; and the air outlet of the induced draft fan is connected to the chimney.

[0021] A flue valve plate is set between the chimney and the furnace at the rear of the heating furnace. When necessary, part or all of the flue gas can be discharged from the rear of the heating furnace. Its purpose is to adjust the temperature distribution of the furnace, reduce the amount of nitrogen oxides generated, and assist in the use of the tail flue when the exhaust of the burner at the head of the heating furnace is not smooth.

[0022] The tubular heating furnace is equipped with a burner with its own heat exchanger and adopts a joint smoke exhaust structure at the head (lower part) and tail (upper part). The air preheater at the tail (upper part) of the heating furnace can be removed to reduce the weight of the heating furnace. Part of the high-temperature flue gas forms a reflux in the furnace, which is beneficial to enhance combustion, heat transfer and temperature uniformity. The ratio of flue gas discharged from the head (lower part) and tail (upper part) is adjusted by the flue valve plate, which can achieve a reasonable distribution of heat supply and flue gas temperature in the furnace, increase the load of the heating furnace and the flexibility of temperature regulation, and meet the needs of high-precision temperature regulation of certain processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural diagram of Example 1 of the present invention;

[0024] Figure 2 This is a structural diagram of embodiment 2 of the present invention;

[0025] Figure 3 It is a schematic diagram of the structure of a tubular heating furnace in the prior art. DETAILED DESCRIPTION

[0026] The specific technical solutions of the present invention are described with reference to the accompanying drawings.

[0027] Example 1

[0028] like Figure 1 As shown, the head exhaust pipe type heating furnace includes a furnace 1, a furnace tube 2, a burner 3, a combustion-supporting fan 6, an induced draft fan 5, a fuel regulating valve 7 and a shut-off valve 8;

[0029] The furnace chamber 1 is provided with a furnace tube 2;

[0030] The burner 3 is mounted at the top or bottom of the furnace 1. A special-shaped baffle 34 is provided inside the burner 3. The internal cavity of the special-shaped baffle 34 is an air passage 32, and the external cavity is a flue gas passage 31. The special-shaped baffle 34, the flue gas passage 31, and the air passage 32 constitute an air preheater 4. One end of the air passage 32 is connected to the combustion-supporting fan 6 via a connecting pipe, and the other end leads to the furnace 1. One end of the flue gas passage 31 is connected to the induced draft fan 5 via a connecting pipe, and the other end leads to the furnace 1.

[0031] A fuel spray gun 33 is installed inside the burner 3 . One end of the fuel spray gun 33 is connected to the fuel regulating valve 7 through a connecting pipe, and the other end leads to the furnace 1 .

[0032] When the tubular heating furnace is working, the fuel enters the furnace 1 through the fuel spray gun 33 and mixes with the combustion air entering the furnace 1 through the air channel 32 of the burner 3 to burn, forming high-temperature flue gas to heat the material in the furnace tube 2. The flow rate of the flue gas is adjusted by the fuel regulating valve 7.

[0033] The flow rate of the combustion air is regulated by the combustion air blower 6 speed inverter.

[0034] The flue gas in the furnace 1 is discharged from the flue gas channel 31 in the burner 3 and discharged to the centralized or independent flue through the connecting pipe and the induced draft fan 5.

[0035] In addition to the head (lower) burner 3 with its own flue gas channel 31, the present invention has a fully enclosed furnace. The burner 3 has its own air preheater 4, which is designed with a combustion air inlet and a flue gas outlet. The flue gas forms a backflow in the furnace due to the opposite inlet and outlet directions. By adopting this head (lower) smoke exhaust structure, the convection section, air preheater and chimney at the rear (upper) of the heating furnace can be completely removed, greatly reducing the volume and weight of the heating furnace; the high-temperature flue gas forms a backflow in the furnace 1, which is conducive to enhancing combustion, heat transfer and temperature uniformity; the flue gas is discharged from the head (lower part). When it is necessary to install a flue gas purification device, it can be achieved on the head ground without changing the furnace body load-bearing structure.

[0036] Example 2

[0037] like Figure 2 As shown, based on Example 1, a chimney 10 is installed at the rear end of the furnace 1, that is, the upper part, and a flue valve plate 9 is provided in the chimney 10; the air outlet of the induced draft fan 5 is connected to the chimney 10.

[0038] By adopting a joint exhaust structure of the head (lower part) and the tail (upper part), and adjusting the ratio of flue gas discharged from the head (lower part) and the tail (upper part) through the flue valve plate 9, a reasonable distribution of heat supply and flue gas temperature in the furnace can be achieved, increasing the load of the heating furnace and the flexibility of temperature regulation, and meeting the needs of high-precision temperature regulation in certain processes. At the same time, the air preheater at the tail (upper part) of the traditional heating furnace can be removed to reduce the weight of the heating furnace; part of the high-temperature flue gas forms a backflow in the furnace, which is conducive to enhancing combustion, heat transfer and temperature uniformity; when the flue gas needs to be purified, an environmental protection device can be installed on the ground of the head without changing the load-bearing structure of the furnace body. At the same time, after installing the flue gas purification and treatment device, the ratio of the treated flue gas at the head and the untreated flue gas at the tail can be adjusted according to the emission control requirements and the actual combustion pollutant generation, so as to achieve the purpose of both meeting emission standards and reducing environmental protection operation costs.

Claims

1. A head exhaust pipe type heating furnace, comprising a furnace (1), a burner (3), a combustion-supporting fan (6), an induced draft fan (5), a fuel regulating valve (7) and a shut-off valve (8); a furnace tube (2) is installed in the furnace (1); It is characterized in that The burner (3) is installed at the head, i.e., the bottom, of the furnace (1). A special-shaped partition (34) is provided inside the burner (3); the internal cavity of the special-shaped partition (34) is an air channel (32), and the external cavity is a flue gas channel (31). The special-shaped partition (34), the flue gas channel (31), and the air channel (32) constitute an air preheater (4); one end of the air channel (32) is connected to the combustion-supporting fan (6) through a connecting pipe, and the other end leads to the furnace (1); one end of the flue gas channel (31) is connected to the induced draft fan (5) through a connecting pipe, and the other end leads to the furnace (1); The flow rate of the combustion-supporting air is adjusted by the speed converter of the combustion-supporting fan (6); A fuel spray gun (33) is installed inside the burner (3), one end of the fuel spray gun (33) is connected to the fuel regulating valve (7) through a connecting pipe, and the other end leads to the furnace (1); A chimney (10) is installed at the tail end, i.e., the upper portion, of the furnace (1), and a flue valve plate (9) is provided between the chimney (10) and the furnace (1); the air outlet of the induced draft fan (5) is connected to the chimney (10); The head or lower exhaust structure is adopted, and the flue gas forms a backflow in the furnace due to the opposite inflow and outflow directions.

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