Electric heating cracking furnace with self-regulation function

Abstract

The invention relates to the technical field of cracking furnaces, in particular to an electric heating cracking furnace with a self-regulation function, which comprises a feeding tank, an upper air pump, a manifold, a cracking core and an extremely cold heat exchanger, a raw material port is arranged on the side wall of the feeding tank, an inlet of the upper air pump is communicated with the feeding tank, an outlet of the upper air pump is connected with the manifold, and the manifold is divided into a plurality of branch pipes to enter the cracking core. The cracking core is directly connected with the extremely-cold heat exchanger, a discharge port is formed in the extremely-cold heat exchanger, the cracking core comprises a plurality of cracking pipes arranged in the shell, the interior of each cracking pipe is in an expansion form, raw materials to be cracked are heated and cracked in the cracking pipes, and the front half section of the expansion section in each cracking pipe is a heating area. By changing the inner shape and structure of the furnace tube, the gas in the radiation heating area can be self-adaptively expanded according to the gas increment in the cracking process, the gas which is expanded and quickly ejected backwards is cracked gas, and the gas which is not fully cracked can stay for a short time in the heating area, so that the gas is fully heated and then cracked.

Description

Technical Field

[0001] The invention relates to the technical field of cracking furnaces, in particular to an electric heating cracking furnace with a self-regulating function. Background Art

[0002] Cracking furnace is a common equipment for processing chemical raw materials. It is mostly used to decompose large molecular hydrocarbon substances into small molecular olefins and hydrogen, and to crack refrigerants into fluorinated monomers. For example, the cracking products of ethane are mainly ethylene, hydrogen, and methane. The cracking products of propane are ethylene, propylene, and hydrogen. The cracking products of mixtures such as naphtha are mainly ethylene, propylene, butadiene, and aromatics. The cracking products of 1,1-difluoro-1-chloroethane are vinylidene fluoride and 1,1,1-trifluoroethane. The cracking products of difluoromonochloromethane are tetrafluoroethylene, hydrogen chloride, and hydrogen chloride. The monomer products are treated and used as subsequent polymer raw materials.

[0003] In the prior art, a cracking furnace is generally only a heating furnace. The raw materials enter the cracking furnace and are subjected to high temperatures, and then decomposed into small molecular products. If the raw materials are exposed to high temperatures for too long or are heated unevenly, over-decomposition may easily occur. A large amount of coke may be easily generated on the inner wall of the cracking furnace tube, which requires frequent cleaning. Alternatively, a large amount of raw material components may not be fully cracked and may be mixed into the product, increasing the subsequent separation process.

[0004] For example, CN116712938A and CN109424963A focus on solving the coking problem. Most problems of cracking furnaces are related to insufficient cracking reaction and excessive cracking. In the prior art, the residence time of raw gas in the heating zone of the cracking furnace is fixed, and it is impossible to examine in real time whether the raw gas is cracked appropriately. Summary of the invention

[0005] The object of the present invention is to provide an electrically heated cracking furnace with a self-regulating function to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions: An electric heating cracking furnace with a self-regulating function, the cracking furnace comprises a feed tank, an upper air pump, a manifold, a cracking core, and an extremely cold heat exchanger. A raw material port is arranged on the side wall of the feed tank, the upper air pump inlet is connected to the feed tank, the upper air pump outlet is connected to the manifold, the manifold is divided into a plurality of branch pipes entering the cracking core, the cracking core is directly connected to the extremely cold heat exchanger, and a discharge port is arranged on the extremely cold heat exchanger. The cracking core includes a plurality of cracking tubes arranged in the shell. The cracking tubes are in an expanded form. The raw materials to be cracked are thermally cracked in the cracking tubes. The front half of the expansion section in the cracking tubes is the heating area.

[0007] The raw materials to be processed enter the feed tank. If they are liquid raw materials, such as naphtha, they need to be gasified first before they can enter the cracking core for full reaction. For room temperature gases such as ethane and propane, they are also buffered in the feed tank first. The core point of this application is that the cracking tube adopts an expansion form, so that the residence time of the raw gas in the cracking area can be automatically adjusted. The cracking reaction is a decomposition reaction, and the molar amount of the substance will increase. Taking ethane cracking as an example, it is cracked into ethylene and hydrogen. One mole of ethane is decomposed into one mole of ethylene and one mole of hydrogen, and the gas amount is doubled. The furnace tube in the traditional cracking furnace is a straight tube, and the gas expansion during the cracking process is not considered. The intake speed is entirely controlled to control the raw gas in the furnace tube. The residence time of the material is prone to insufficient or excessive cracking. Among them, the entire furnace tube is heated, and the components that have been cracked are the main reason for further cracking due to the high temperature. Although there is a heat exchanger for cooling later, the distance is far. In the present application, the expandable cracking tube, after the raw gas is cracked in the cracking tube, the expanded components spontaneously move backward quickly and have space for expansion. After the gas expands, the temperature decreases, reducing the situation of further cracking. If the cracking is insufficient, the raw gas can prolong the residence time in the heating area when entering the cracking tube, so that it can react fully, thereby achieving the core purpose of self-regulating the residence time in the cracking area.

[0008] The cracking furnace also includes a buffer tank, which is arranged between the feed tank and the upper air pump. A temperature control sensor and a heating module are arranged in the buffer tank.

[0009] The buffer tank is used to accurately control the temperature of the raw gas before it enters the cracking core, keeping the raw gas within a range of about fifty degrees. For example, the propane gas is heated to a range of 250-300°C before cracking, reducing the need to heat the cracking tube to 700-800°C. It also controls the uniformity of the components before they enter the cracking area to prevent temperature fluctuations.

[0010] The cracking tube includes a tube head, a tube body, an inner cone, and a radiation surface. The outer surface of the tube body is fixed to the outer shell of the cracking core. The tube head is arranged at one end of the tube body. The end of the tube body away from the tube head is directly connected to the extremely cold heat exchanger. The radiation surface is arranged on the inner wall of the end of the tube body close to the tube head. The tube body gradually expands from one end of the tube head. The tube head is arranged with an inner cone toward the inside of the tube body. A plurality of jet ports distributed circumferentially are arranged on the tube head, and the jet ports are connected to the manifold.

[0011] The radiation surface can be an inner wall on which dense electric heating wires are laid to heat up and radiate after being energized. Attention should be paid to the required temperature, and high-temperature resistant tungsten, molybdenum and other alloy wires should be selected to withstand the temperature of 800 to 900 degrees required for cracking. The raw gas enters the cracking tube from the jet port, and is thermally cracked and expanded in a gradually expanding annular area. The cracked components expand rapidly and move backward to cool down, while the uncracked components can stay near the jet port for a longer time, and all gas ports share the heating and expansion space.

[0012] The air jets are arranged in a circular array and are spaced alternately to discharge air.

[0013] If the gas is discharged from the jets at the same time, there may be insufficient expansion space. For cracking reactions with high cracking ratios, such as the cracking of C10H22 into small molecular olefin components, the reaction formula is C10H22=5C2H4+H2, with a six-fold molar increment. Therefore, a large expansion space is required to successfully achieve the purpose of self-regulating residence time mentioned above. Under this working condition, a few jets are used alternately. Taking the twelve jets distributed circumferentially on the tube head as an example, when it is applied to the cracking of large molecular components, each pulse only injects raw materials from two jets at twelve and six o'clock, and then two jets at one and seven o'clock, and so on. For the cracking of small molecular propane, the four jets at twelve, three, six and nine o'clock can be opened and rotated in sequence during each pulse intake.

[0014] The cracking core also includes a one-way nozzle, which is arranged at each jet port. When the medium flows in the one-way nozzle, the flow resistance in the direction toward the tube body is less than the reverse flow resistance.

[0015] In order to prevent the expansion process of the gas in the tube from being transmitted toward the air intake direction during decomposition and thus affecting the air intake volume, a one-way nozzle is set at the air intake position to prevent the expansion pressure from being applied in the air intake direction.

[0016] A plurality of cone openings are axially distributed in the one-way nozzle, and the cone tips face the tube body.

[0017] The one-way nozzle allows gas to flow quickly, with the conical mouth facing the tube body, so that the inlet resistance remains basically unchanged but has greater resistance during reverse flow. The above structure is a way to achieve one-way resistance, and other structures with similar effects in the valve field can also be applied.

[0018] The manifold includes a one-way valve, a multi-way pipe, a gas distribution plate, and a gas transmission hose. The inlet of the one-way valve is connected to the upper air pump, and the outlet of the one-way valve is connected to the multi-way pipe. The other end of the multi-way pipe is provided with a gas distribution plate, and the gas distribution plate is connected to the one-way nozzle through the gas transmission hose. The number of one-way valves is equal to the total number of one-way nozzles on each cracking tube divided by the number of single openings, and the number of branches of the multi-way pipe is equal to the number of internal cracking tubes.

[0019] The manifold is used to distribute gas on each cracking tube. When one-third of the jets on a single cracking tube are opened in each pulse cycle, three one-way valves are required to control the gas supply. The same number of branch pipes as the cracking tube can be connected behind the one-way valve. In the above description, under the condition of cracking of macromolecular components, the proportion of the jets opened each time is reduced, and the number of one-way valves needs to be increased accordingly. The manifolds with different ratios should be replaced according to different working conditions. The gas hose is a metal hose that can withstand the residual temperature of the environment in the cracking core.

[0020] A solenoid valve is respectively arranged at one end of the one-way nozzle away from the pipe head, and the one-way nozzles are uniformly connected to the upper air pump.

[0021] Alternatively, more control valves may be provided to control the air intake status at each one-way nozzle separately. However, the disadvantage is that the valves are too close to the hot zone and there are too many of them, which may increase the failure rate.

[0022] The cracking furnace also includes a water tank, a steam pipe, and a return pipe. The water tank is placed next to the extremely cold heat exchanger. The water tank supplies cold flow medium to the extremely cold heat exchanger through a water pump. The cooling medium outlet of the extremely cold heat exchanger is connected to the feed tank through a steam pipe, and the side wall of the feed tank is connected to the water tank through a return pipe.

[0023] There is a large amount of heat recovery at the extremely cold heat exchanger, which is traditionally used directly for preheating and heating of raw materials, and there are major problems such as uneven distribution of heat and cold. This application adds water as an intermediate medium for heat transfer to improve the temperature controllability, and focuses on improving the problem of rapid cooling of the cracked components at the extremely cold heat exchanger. The heated water enters the feed tank in the form of steam for preliminary raw material preheating, and the preheating temperature is precisely controlled in the buffer tank.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: the present application changes the shape and structure inside the furnace tube so that the gas in the radiation heating zone can adaptively expand according to the gas increment in the cracking process. The gas that expands and quickly ejects backwards is the gas that has been cracked, while the gas that is not fully cracked can stay in the heating zone for a short time and then be cracked after being fully heated, thereby achieving the purpose of adaptively adjusting the residence time of the components in the heating zone; according to different cracking conditions, the air intake volume can be adjusted by the ratio of the amount of the jet opening in each pulse cycle, so as to fully share the same cracking expansion space and achieve efficient adjustment under specific conditions. The cracked gas is directly connected to the heat exchanger for rapid cooling to prevent further cracking or coking. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a front view of the present invention; Figure 3 This is a schematic diagram of the connection relationship between the cracking tube, the one-way nozzle and the manifold of the present invention; Figure 4 This is a schematic diagram of the internal structure of the cracking tube of the present invention; Figure 5 It is a schematic diagram of the internal structure of the one-way nozzle of the present invention.

[0026] In the figure: 1. feed tank; 19. raw material port; 2. buffer tank; 3. upper air pump; 4. manifold; 41. one-way valve; 42. multi-way pipe; 43. gas distribution plate; 44. gas hose; 5. cracking core; 51. cracking tube; 511. pipe head; 512. tube body; 513. inner cone; 514. radiation surface; 515. jet nozzle; 52. one-way nozzle; 521. cone mouth; 6. ultra-cold heat exchanger; 69. discharge port; 7. water tank; 81. steam pipe; 82. return pipe. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] An electric heating cracking furnace with a self-regulating function, the cracking furnace comprises a feed tank 1, an upper air pump 3, a manifold 4, a cracking core 5, and an extremely cold heat exchanger 6. A raw material port 19 is arranged on the side wall of the feed tank 1, the inlet of the upper air pump 3 is connected to the feed tank 1, the outlet of the upper air pump 3 is connected to the manifold 4, the manifold 4 is divided into a plurality of branch pipes and enters the cracking core 5, the cracking core 5 is directly connected to the extremely cold heat exchanger 6, and a discharge port 69 is arranged on the extremely cold heat exchanger 6. The cracking core 5 includes a plurality of cracking tubes 51 arranged in the shell. The cracking tubes 51 are in an expanded form. The raw materials to be cracked are thermally cracked in the cracking tubes 51. The front half of the expanded section in the cracking tubes 51 is a heating area.

[0029] like Figure 1 , 2As shown in Figure 3, the raw material to be processed enters the feed tank 1. If it is a liquid raw material, such as naphtha, it needs to be gasified first before entering the cracking core 5 for full reaction. For room temperature gas such as ethane and propane, it is also buffered in the feed tank 1 first. The core point of the present application is that the cracking tube 51 adopts an expansion form, so that the residence time of the raw gas in the cracking area can be automatically adjusted. The cracking reaction is a decomposition reaction, and the molar amount of the substance will increase. Taking ethane cracking as an example, it is cracked into ethylene and hydrogen. One mole of ethane is decomposed into one mole of ethylene and one mole of hydrogen, and the gas amount is doubled. The furnace tube in the traditional cracking furnace is a straight tube, and the gas expansion during the cracking process is not considered. The intake speed is entirely used to control the raw gas in the furnace. The residence time in the tube is prone to insufficient or excessive cracking of the material. The entire furnace tube is heated, and the components that have been cracked are the main reason for further cracking due to the high temperature. Although there is a heat exchanger for cooling down later, the distance is far. In the present application, the expandable cracking tube 51, after the raw gas is cracked in the cracking tube 51, the expanded components spontaneously move backward quickly and have space for expansion. After the gas expands, the temperature decreases, reducing the situation of further cracking. If the cracking is insufficient, the raw gas can prolong its residence time in the heating area after entering the cracking tube 51, so that it can react fully, thereby achieving the core purpose of self-regulating the residence time in the cracking area.

[0030] The cracking furnace also includes a buffer tank 2, which is arranged between the feed tank 1 and the upper air pump 3. A temperature control sensor and a heating module are arranged in the buffer tank 2.

[0031] The buffer tank 2 is used to accurately control the temperature of the raw gas before entering the cracking core 5, so that the raw gas is within a range of about fifty degrees. For example, the propane gas is heated to a range of 250-300°C before cracking, thereby reducing the need to heat the cracking tube 51 to 700-800°C. It also controls the uniformity of the components before entering the cracking area to prevent temperature fluctuations.

[0032] The cracking tube 51 includes a tube head 511, a tube body 512, an inner cone 513, and a radiation surface 514. The outer surface of the tube body 512 is fixed to the outer shell of the cracking core 5. The tube head 511 is arranged at one end of the tube body 512. The end of the tube body 512 away from the tube head 511 is directly connected to the extremely cold heat exchanger 6. The radiation surface 514 is arranged on the inner wall of the end of the tube body 512 close to the tube head 511. The tube body 512 gradually expands from one end of the tube head 511. The tube head 511 is arranged with an inner cone 513 toward the inside of the tube body 512. A plurality of jet ports 515 distributed circumferentially are arranged on the tube head 511, and the jet ports 515 are connected to the manifold 4.

[0033] like Figure 3 , 4As shown, the radiation surface 514 can be an inner wall on which dense electric heating wires are laid to heat up and radiate after being energized. Attention should be paid to the required temperature, and high-temperature resistant tungsten, molybdenum and other alloy wires should be selected to withstand the temperature of 800 to 900 degrees required for cracking. The raw gas enters the cracking tube 51 from the jet port 515, and is thermally cracked and expanded in a gradually expanding annular area. The cracked components expand rapidly and move backward to cool down, while the uncracked components can stay near the jet port 515 for a long time, and all gas ports share the heating and expansion space.

[0034] The air jets 515 are arranged in a circular array and alternately emit air.

[0035] like Figure 3 , 4 As shown, if the jets 515 are discharged uniformly, there may be a situation where there is insufficient expansion space. For cracking reactions with high cracking ratios, such as the cracking of C10H22 into small molecular olefin components, the reaction formula is C10H22=5C2H4+H2, with a six-fold molar increment, so a large expansion space is required to successfully achieve the purpose of self-regulating residence time as mentioned above. Under this working condition, a few jets 515 are used alternately. Taking the twelve jets 515 distributed circumferentially on the pipe head 511 as an example, when applied to the cracking of large molecular components, each pulse only injects raw materials from two jets 515 at twelve o'clock and six o'clock, and then two jets 515 at one o'clock and seven o'clock, and so on. For the cracking of small molecular propane, the four jets 515 at twelve o'clock, three o'clock, six o'clock, and nine o'clock can be opened and rotated in sequence during each pulse intake.

[0036] The cracking core 5 further includes a one-way nozzle 52 , which is arranged at each air jet port 515 . When the medium flows in the one-way nozzle 52 , the flow resistance in the direction toward the tube body 512 is smaller than the reverse flow resistance.

[0037] In order to prevent the expansion process of the gas in the tube body 512 from being transmitted toward the air intake direction and then affecting the air intake amount when the gas is cracked, a one-way nozzle 52 is provided at the air intake position to prevent the expansion pressure from being applied in the air intake direction.

[0038] A plurality of cone openings 521 are axially distributed in the one-way nozzle 52 , with the cone tips facing the tube body 512 .

[0039] like Figure 5 As shown, the one-way nozzle 52 allows gas to flow quickly, and the conical mouth 521 faces the tube body 512, so that the inlet resistance remains basically unchanged while there is greater resistance during reverse flow. The above structure is a way to achieve one-way resistance, and other structures with similar effects in the valve field can also be applied.

[0040] The manifold 4 includes a one-way valve 41, a multi-way pipe 42, a gas distributor 43, and a gas delivery hose 44. The inlet of the one-way valve 41 is connected to the upper air pump 3, and the outlet of the one-way valve 41 is connected to the multi-way pipe 42. The other end of the multi-way pipe 42 is provided with a gas distributor 43, and the gas distributor 43 is connected to the one-way nozzle 52 through the gas delivery hose 44. The number of one-way valves 41 is equal to the total number of one-way nozzles 52 on each cracking tube 51 divided by the number of single openings, and the number of branches of the multi-way tube 42 is equal to the number of internal cracking tubes 51 .

[0041] like Figure 3 As shown, the manifold 4 is used for gas distribution on each cracking tube 51. Only one cracking tube 51 and a single-way manifold 4 are shown in the figure. When the jet port 515 on a single cracking tube 51 selects one-third of the ports to be opened in each pulse cycle, three single-way valves 41 are required to control the gas supply. The rear of the single-way valve 41 can be connected to the same number of branch pipes as the cracking tube 51. In the above description, under the working condition of cracking the macromolecular component, the proportion of the jet port 515 opened each time is reduced, and the number of single-way valves 41 needs to be increased accordingly, and the manifolds 4 with different ratios need to be replaced according to different working conditions. The gas delivery hose 44 is a metal hose that withstands the ambient residual temperature in the cracking core.

[0042] A solenoid valve is respectively provided at one end of the one-way nozzle 52 away from the pipe head 511 , and the one-way nozzle 52 is uniformly connected to the upper air pump 3 .

[0043] Alternatively, more control valves may be provided to control the air intake state of each one-way nozzle 52 separately. However, the disadvantage is that the valves are too close to the hot zone and there are too many of them, which may increase the failure rate.

[0044] The cracking furnace also includes a water tank 7, a steam pipe 81, and a return pipe 82. The water tank 7 is placed next to the extremely cold heat exchanger 6. The water tank 7 supplies cold flow medium to the extremely cold heat exchanger 6 through a water pump. The cooling medium outlet of the extremely cold heat exchanger 6 is connected to the feed tank 1 through the steam pipe 81, and the side wall of the feed tank 1 is connected to the water tank 7 through the return pipe 82.

[0045] like Figure 1 As shown, there is a large amount of heat recovery at the extremely cold heat exchanger 6. Traditionally, it is mostly used directly for preheating and heating of raw materials, and there are major problems such as uneven distribution of hot and cold. The present application adds water as an intermediate medium for heat transfer to improve the temperature controllability, and focuses on improving the problem of rapid cooling of the cracked components at the extremely cold heat exchanger 6. The heated water enters the feed tank 1 in the form of steam for preliminary raw material preheating, and the preheating temperature is precisely controlled in the buffer tank 2.

[0046] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. An electrically heated cracking furnace with self-regulating function, characterized in that: The cracking furnace comprises a feed tank (1), an upper air pump (3), a manifold (4), a cracking core (5), and an extremely cold heat exchanger (6). A raw material port (19) is arranged on a side wall of the feed tank (1). The inlet of the upper air pump (3) is connected to the feed tank (1). The outlet of the upper air pump (3) is connected to the manifold (4). The manifold (4) is divided into a plurality of branch pipes and enters the cracking core (5). The cracking core (5) is directly connected to the extremely cold heat exchanger (6). A discharge port (69) is arranged on the extremely cold heat exchanger (6). The cracking core (5) comprises a plurality of cracking tubes (51) arranged in a shell, wherein the cracking tubes (51) are in an expanded form, and the raw material to be cracked is thermally cracked in the cracking tubes (51), and the front half of the expanded section in the cracking tubes (51) is a heating area.

2. The electrically heated cracking furnace with self-regulating function according to claim 1, characterized in that: The cracking furnace further comprises a buffer tank (2), wherein the buffer tank (2) is arranged between the feed tank (1) and the upper air pump (3), and a temperature control sensor and a heating module are arranged in the buffer tank (2).

3. The electrically heated cracking furnace with self-regulating function according to claim 2, characterized in that: The cracking tube (51) comprises a tube head (511), a tube body (512), an inner cone (513), and a radiation surface (514); the outer surface of the tube body (512) is fixed to the outer shell of the cracking core (5); the tube head (511) is arranged at one end of the tube body (512); the end of the tube body (512) away from the tube head (511) is directly connected to the extremely cold heat exchanger (6); the radiation surface (514) is arranged on the inner wall of the end of the tube body (512) close to the tube head (511); the tube body (512) gradually expands from one end of the tube head (511); the tube head (511) is arranged with an inner cone (513) toward the inside of the tube body (512); a plurality of jet ports (515) distributed circumferentially are arranged on the tube head (511); the jet ports (515) are connected to the manifold (4).

4. The electrically heated cracking furnace with self-regulating function according to claim 3, characterized in that: The air jets (515) are arranged in a circular array to emit air in alternating intervals.

5. The electrically heated cracking furnace with self-regulating function according to claim 4, characterized in that: The cracking core (5) further comprises a one-way nozzle (52), wherein the one-way nozzle (52) is arranged at each air jet port (515), and when the medium flows in the one-way nozzle (52), the flow resistance in the direction toward the tube body (512) is smaller than the reverse flow resistance.

6. The electrically heated cracking furnace with self-regulating function according to claim 5, characterized in that: A plurality of cone openings (521) are axially distributed inside the one-way nozzle (52), with the cone tips facing the tube body (512).

7. The electrically heated cracking furnace with self-regulating function according to claim 5, characterized in that: The manifold (4) comprises a one-way valve (41), a multi-way pipe (42), a gas distribution plate (43), and a gas delivery hose (44). The inlet of the one-way valve (41) is connected to the upper air pump (3), and the outlet of the one-way valve (41) is connected to the multi-way pipe (42). The other end of the multi-way pipe (42) is provided with a gas distribution plate (43). The gas distribution plate (43) is connected to the one-way nozzle (52) via the gas delivery hose (44). The number of the one-way valves (41) is equal to the total number of one-way nozzles (52) on each cracking tube (51) divided by the number of single openings, and the number of branches of the multi-way tube (42) is equal to the number of internal cracking tubes (51).

8. The electrically heated cracking furnace with self-regulating function according to claim 5, characterized in that: A solenoid valve is respectively provided at one end of the one-way nozzle (52) away from the pipe head (511), and the one-way nozzle (52) is uniformly connected to the upper air pump (3).

9. The electrically heated cracking furnace with self-regulating function according to claim 5, characterized in that: The cracking furnace further comprises a water tank (7), a steam pipe (81), and a return pipe (82). The water tank (7) is placed beside the extreme cold heat exchanger (6). The water tank (7) supplies cold flow medium to the extreme cold heat exchanger (6) via a water pump. The cooling medium outlet of the extreme cold heat exchanger (6) is connected to the feed tank (1) via the steam pipe (81). The side wall of the feed tank (1) is connected to the water tank (7) via the return pipe (82).

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