An electric heating cracking furnace with self-regulation function

Abstract

The present invention relates to the technical field of cracking furnaces, specifically an electrically heated cracking furnace with self-regulation function. The cracking furnace includes a feed tank, an upper gas pump, a pipe manifold, a cracking core, and an extremely cold heat exchanger. A raw material port is provided on the side wall of the feed tank. The inlet of the upper gas pump is connected to the feed tank, and the outlet of the upper gas pump is connected to the pipe manifold. The pipe manifold is divided into several branch pipes and enters the cracking core. The cracking core is directly connected to the extremely cold heat exchanger, and a discharge port is provided on the extremely cold heat exchanger. The cracking core includes several cracking tubes arranged in a housing. The inside of the cracking tubes is in an expanded form. The raw material to be cracked is heated and cracked in the cracking tubes. The first half of the expanded section in the cracking tubes is the heating area. By changing the shape and structure inside the furnace tubes, the gas in the radiation heating area can expand adaptively according to the gas increment during the cracking process. The gas that expands and quickly sprays backward is the gas that has been cracked, while the gas that has not been fully cracked can stay in the heating area for a short time, and then be fully heated and cracked after sufficient temperature rise.

Description

Technical Field

[0001] The present invention relates to the technical field of cracking furnaces, and specifically relates to an electrically heated cracking furnace with a self-regulation function. Background Art

[0002] A cracking furnace is a commonly used device for processing chemical raw materials, and is mostly used for decomposing macromolecular hydrocarbon substances into small-molecular olefins and hydrogen, refrigerant cracking into fluorine-containing monomers, etc. For example, the cracking products of ethane are mainly ethylene, hydrogen, and methane, the cracking products of propane are ethylene, propylene, and hydrogen, etc., the main cracking products of mixtures such as naphtha are ethylene, propylene, butadiene, and aromatics, the cracking products of 1,1-difluoro-1-chloroethane are vinylidene fluoride and 1,1,1-trifluoroethane, and the cracking products of dichlorofluoromethane are tetrafluoroethylene, hydrogen chloride, etc. After obtaining the monomer products through processing, they are used as raw materials for subsequent polymers.

[0003] In the prior art, a cracking furnace is generally just a heating furnace. The raw material enters the cracking furnace and is subjected to high temperature, and then decomposes into small-molecule products. If it is in contact with high temperature for too long or the heating is uneven, over-decomposition is likely to occur, and a large amount of coke is easily generated on the inner wall of the cracking furnace tubes, which requires frequent cleaning. Or a large amount of raw material components are not fully cracked and are mixed into the products, 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 over-cracking. In the prior art, the residence time of the raw material gas in the heating zone of the cracking furnace is a fixed design, and the factor of whether the raw material gas is cracked appropriately cannot be examined in real time. Summary of the Invention

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

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] An electrically heated cracking furnace with a self-regulation function, the cracking furnace includes a feed tank, an upper gas pump, a pipe manifold, a cracking core, and an extremely cold heat exchanger. A raw material port is provided on the side wall of the feed tank. The inlet of the upper gas pump is connected to the feed tank, and the outlet of the upper gas pump is connected to the pipe manifold. The pipe manifold is divided into several branch pipes and enters the cracking core. The cracking core is directly connected to the extremely cold heat exchanger, and a discharge port is provided on the extremely cold heat exchanger.

[0008] The cracking core includes several cracking tubes arranged in a shell. The inside of the cracking tubes is in an expanded form. The raw material to be cracked is heated and cracked in the cracking tubes. The first half of the expanded section in the cracking tubes is the heating area.

[0009] The raw materials to be processed enter the feed tank. If they are liquid raw materials, such as naphtha, etc., they need to be gasified first before entering the cracking core for full reaction. For ethane, propane and other gaseous substances at normal temperature, they are also buffered in the feed tank first. The core point of this application is that the cracking tube adopts an expanding form, so that the residence time of the raw material gas in the cracking area can be automatically adjusted. The cracking reaction is a decomposition reaction, and the amount of substance in moles will increase. Taking the cracking of ethane as an example, it cracks into ethylene and hydrogen. One mole of ethane decomposes into one mole of ethylene and one mole of hydrogen, and the gas volume doubles. The furnace tubes in traditional cracking furnaces are straight tubes, without considering the gas expansion during the cracking process. The residence time of the raw material gas in the furnace tubes is entirely controlled by the intake speed, and it is easy for substances to be insufficiently cracked or over-cracked. Among them, the entire section of the furnace tube is heated. The components that have been cracked continue to crack mainly because they maintain a high temperature. Although there is a heat exchanger for cooling later, the distance is relatively far. In this application, in the expanding cracking tube, after the raw material gas cracks in the cracking tube, the expanded components spontaneously move backward quickly, and there is space for them to expand. After the gas expands, the temperature decreases, reducing the further cracking situation. If the cracking is insufficient, the raw material gas can extend the residence time in the heating area when entering the cracking tube, so that the reaction is sufficient, thereby achieving the core purpose of self-regulating the residence time in the cracking area.

[0010] The cracking furnace further includes a buffer tank, which is arranged between the feed tank and the upper gas pump, and a temperature control sensor and a heating module are arranged in the buffer tank.

[0011] The buffer tank is used to precisely control the temperature of the raw material gas before entering the cracking core, so that the raw material gas is within an interval of about fifty degrees. For example, before the cracking of propane gas, it is heated to the range of 250-300 °C, reducing the heating requirement for the cracking tube to rise to 700-800 °C, and also controlling the uniformity of the components as much as possible before entering the cracking area to prevent temperature difference fluctuations.

[0012] 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. One end of the tube body is provided with a tube head, and the end of the tube body far from the tube head is directly connected to the cryogenic heat exchanger. A radiation surface is arranged on the inner wall of the tube body near the tube head. The tube body gradually expands from the tube head end. The inner cone is arranged towards the inside of the tube body on the tube head, and a number of jet ports are arranged on the tube head in a circumferential distribution, and the jet ports are communicated with the pipe manifold.

[0013] The radiation surface can be that dense electric heating wires are laid on the inner wall and heated by power-on for radiation. It is necessary to pay attention to the required temperature and select high-temperature-resistant alloy wires such as tungsten and molybdenum that can withstand the temperature of eight or nine hundred degrees required for cracking. The raw material gas enters the cracking tube from the jet ports, is heated and cracked and expanded in an annular and gradually expanding area. The cracked components expand rapidly and move backward to cool down, while the uncracked components can stay near the jet ports for a longer time. All the gas ports share the heating and expansion space.

[0014] The jet nozzles are arranged in a circumferential array and discharge gas alternately at intervals.

[0015] If the jet nozzles discharge gas uniformly, there may be insufficient expansion space. For cracking reactions with a high cracking ratio, such as the cracking of C10H22 into small-molecule olefin components, the reaction formula is C10H22 = 5C2H4 + H2, with a six-fold molar increase. Therefore, a large expansion space is required to smoothly achieve the purpose of self-regulating the residence time mentioned above. Under this working condition, a few jet nozzles are used alternately. Taking twelve jet nozzles distributed circumferentially on the pipe head as an example, when applied to the cracking of macromolecular components, the raw materials are injected only from the two jet nozzles at the 12 o'clock and 6 o'clock directions during each pulse, and then from the two jet nozzles at the 1 o'clock and 7 o'clock directions, and so on. For the cracking of small-molecule propane, four jet nozzles at 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock can be opened and rotated in sequence during each pulse intake.

[0016] The cracking core also includes a one-way nozzle, which is arranged at each jet nozzle. When the medium flows in the one-way nozzle, the flow resistance in the direction towards the pipe body is less than the reverse flow resistance.

[0017] To prevent the expansion process during gas cracking in the pipe body from being transmitted towards the intake direction and then affecting the intake volume, a one-way nozzle is set at the intake position to prevent the expansion pressure from being applied towards the intake direction.

[0018] A number of conical orifices are axially distributed in the one-way nozzle, with the cone tips facing the pipe body.

[0019] The one-way nozzle allows gas to flow through quickly. The conical orifices face the pipe body, so the inflow resistance is basically unchanged while having a large resistance during reverse flow. The above structure is a way to achieve one-way resistance, and structures with similar effects in other fields of valves can also be applied.

[0020] The pipe manifold includes a single-way valve, a multi-way pipe, a gas distribution plate, and a gas transmission hose. The inlet of the single-way valve is connected to an upper air pump, the outlet of the single-way valve is connected to the multi-way pipe, the other end of the multi-way pipe is respectively 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 single-way valves is equal to the total number of one-way nozzles on each cracking pipe divided by the number of nozzles opened each time, and the number of branches of the multi-way pipe is equal to the number of inner cracking pipes.

[0021] The pipe manifold is used for the distribution of gas on each cracking pipe. When one-third of the nozzles on a single cracking pipe are selected to be opened in each pulse cycle, three single-way valves are required for upper air control. The same number of branch pipes as the cracking pipes can be connected behind the single-way valve. In the previous description, under the working condition of cracking macromolecular components, the proportion of jet nozzles opened each time decreases, and the number of single-way valves needs to be increased accordingly. Different pipe manifolds with different ratios are replaced according to different working conditions. The gas transmission hose is a metal hose that can withstand the remaining temperature in the cracking core environment.

[0022] One-way nozzles are respectively provided with solenoid valves at the ends far away from the pipe heads, and the one-way nozzles are uniformly connected to the upper air pump.

[0023] It can also be to separately control the intake air state at each one-way nozzle by setting more control valves. The disadvantage is that the valves are too close to the hot zone and the number is too large, so the failure rate may increase.

[0024] The cracking furnace further includes a water tank, a steam pipe, and a return water pipe. The water tank is placed beside 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 water pipe.

[0025] There is a large amount of heat recovery at the extremely cold heat exchanger. Conventionally, it is mostly directly used for preheating and temperature raising of raw materials, and there are main problems such as uneven cold and heat distribution. In this application, water is added as an intermediate medium for heat transfer to improve the temperature controllability, and the problem of quickly cooling the components after cracking at the extremely cold heat exchanger is mainly improved. 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.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: By changing the internal shape structure of the furnace tube, the gas in the radiation heating zone can adaptively expand according to the gas increment during the cracking process. The gas that expands and quickly sprays backward is the gas that has been cracked, while the gas that has not been fully cracked can stay in the heating zone for a short time, and then be fully heated and cracked after staying for a short time, so as to achieve the purpose of adaptively adjusting the residence time of the components in the heating zone; According to different cracking conditions, the intake air volume can be adjusted by the proportion of the number of jet orifices opened 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

[0027] Figure 1 It is a schematic diagram of the overall external structure of the present invention;

[0028] Figure 2 It is a front view of the present invention;

[0029] Figure 3 It is a schematic diagram of the connection relationship between the cracking tube, the one-way nozzle, and the pipe manifold of the present invention;

[0030] Figure 4 It is a schematic diagram of the internal structure of the cracking tube of the present invention;

[0031] Figure 5 It is a schematic diagram of the internal structure of the one-way nozzle of the present invention.

[0032] In the figure: 1, feed tank; 19, raw material inlet; 2, buffer tank; 3, upper air pump; 4, pipe manifold; 41, single-way valve; 42, multi-way pipe; 43, gas distribution plate; 44, gas transmission hose; 5, cracking core; 51, cracking tube; 511, tube head; 512, tube body; 513, inner cone; 514, radiation surface; 515, jet orifice; 52, one-way nozzle; 521, conical orifice; 6, cryogenic heat exchanger; 69, discharge port; 7, water tank; 81, steam pipe; 82, return water pipe. Detailed implementation mode

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] An electric heating cracking furnace with a self-regulation function, the cracking furnace includes a feed tank 1, an upper air pump 3, a pipe manifold 4, a cracking core 5, and a cryogenic heat exchanger 6. A raw material inlet 19 is provided on the side wall of the feed tank 1. The inlet of the upper air pump 3 is connected to the feed tank 1, and the outlet of the upper air pump 3 is connected to the pipe manifold 4. Several branch pipes of the pipe manifold 4 enter the cracking core 5, and the cracking core 5 is directly connected to the cryogenic heat exchanger 6. A discharge port 69 is provided on the cryogenic heat exchanger 6.

[0035] The cracking core 5 includes several cracking tubes 51 arranged in a housing. The inside of the cracking tube 51 is in an expanded form, and the raw material to be cracked is heated and cracked in the cracking tube 51. The first half of the expanded section in the cracking tube 51 is the heating area.

[0036] Such as Figure 1 、 2As shown in FIGS. 3, the raw materials to be processed enter the feed tank 1. If they are liquid raw materials, such as naphtha, etc., they need to be gasified first before entering the cracking core 5 for full reaction. For ethane, propane, etc. which are gaseous at room temperature, they are also buffered in the feed tank 1 first. The core point of this application is that the cracking tube 51 adopts an expanding form, so as to be able to automatically adjust the residence time of the raw material gas in the cracking area. The cracking reaction is a decomposition reaction, and the amount of substance in moles will increase. Taking the cracking of ethane as an example, it cracks into ethylene and hydrogen. One mole of ethane decomposes into one mole of ethylene and one mole of hydrogen, and the gas volume doubles. In a traditional cracking furnace, the furnace tubes are straight tubes, without considering the gas expansion during the cracking process, and the residence time of the raw material gas in the furnace tubes is entirely controlled by the intake speed, so it is easy for substances to be insufficiently cracked or over-cracked. Among them, the entire section of the furnace tube is heated. The components that have been cracked are the main reason for further cracking due to maintaining high temperature. Although there is a heat exchanger for cooling later, the distance is relatively far. In this application, for the expanding cracking tube 51, after the raw material gas cracks in the cracking tube 51, the expanded components spontaneously move backward rapidly and there is space for them to expand. After the gas expands, the temperature decreases, reducing the situation of further cracking. If the cracking is insufficient, the raw material gas can increase the residence time in the heating area when entering the cracking tube 51, so as to make the reaction sufficient, thus achieving the core purpose of self-regulating the residence time in the cracking area.

[0037] The cracking furnace further includes a buffer tank 2, which is arranged between the feed tank 1 and the upper gas pump 3, and a temperature control sensor and a heating module are arranged in the buffer tank 2.

[0038] The buffer tank 2 is used to precisely control the temperature of the raw material gas before entering the cracking core 5, so that the raw material gas is within an interval of about fifty degrees. For example, before the cracking of propane gas, it is heated to the range of 250 - 300 °C, reducing the heating requirement for the cracking tube 51 to rise to 700 - 800 °C, and also controlling the uniformity of the components as much as possible before entering the cracking area to prevent temperature difference fluctuations.

[0039] 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. One end of the tube body 512 is provided with the tube head 511, and the end of the tube body 512 far from the tube head 511 is directly connected to the cryogenic heat exchanger 6. The radiation surface 514 is arranged on the inner wall of the tube body 512 near the tube head 511. The tube body 512 gradually expands from the end of the tube head 511. The inner cone 513 is arranged towards the inside of the tube body 512 on the tube head 511, and a number of jet ports 515 distributed in a circumferential manner are arranged on the tube head 511, and the jet ports 515 are communicated with the pipe manifold 4.

[0040] As Figure 3 、 4As shown, the radiation surface 514 can be the inner wall where dense electric heating wires are laid to heat up and radiate after being electrified. Attention should be paid to the required temperature, and alloy wires such as tungsten and molybdenum that can withstand high temperatures should be selected to withstand the temperature of eight or nine hundred degrees required for cracking. The raw material gas enters the cracking tube 51 from the jet nozzle 515, and is heated and cracked and expanded in an annular and gradually expanding area. The components after cracking expand rapidly and move backward to cool down, while the uncracked components can stay near the jet nozzle 515 for a longer time. All the gas nozzles share the heating and expansion space.

[0041] The jet nozzles 515 discharge gas alternately at intervals in a circumferential array.

[0042] As Figure 3 、 4 As shown, if the jet nozzles 515 discharge gas uniformly, there may be a situation of insufficient expansion space. For cracking reactions with a high cracking ratio, such as the cracking of C10H22 into small molecule olefin components, the reaction formula is C10H22 = 5C2H4 + H2, with a six-fold molar increment. Therefore, a large expansion space is required to smoothly achieve the purpose of self-regulating the residence time mentioned above. In this working condition, a few jet nozzles 515 are used alternately. Taking the twelve jet nozzles 515 distributed circumferentially on the pipe head 511 as an example, when applied to the cracking of macromolecular components, the raw material is injected only from the two jet nozzles 515 at the twelve o'clock and six o'clock directions for each pulse, and then the two jet nozzles 515 at the one o'clock and seven o'clock directions, and so on. For the cracking of small molecule propane, four jet nozzles 515 at twelve o'clock, three o'clock, six o'clock, and nine o'clock can be opened and rotated in turn during each pulse intake.

[0043] The cracking core 5 further includes a one-way nozzle 52, and the one-way nozzle 52 is arranged at each jet nozzle 515. When the medium flows in the one-way nozzle 52, the flow resistance in the direction towards the pipe body 512 is less than the reverse flow resistance.

[0044] To prevent the expansion process during gas cracking in the pipe body 512 from being transmitted towards the intake direction and thus affecting the intake volume, a one-way nozzle 52 is set at the intake position to prevent the expansion pressure from being applied towards the intake direction.

[0045] A number of tapered openings 521 are axially distributed in the one-way nozzle 52, and the tapered tips face the pipe body 512.

[0046] As Figure 5 As shown, the one-way nozzle 52 allows the gas to flow through quickly. The tapered openings 521 face the pipe body 512, so that the inlet flow resistance is basically unchanged while having a large resistance during reverse flow. The above structure is a way to achieve one-way resistance, and structures with other similar effects in the valve field can also be applied.

[0047] The pipe manifold 4 includes a single-way valve 41, a multi-way pipe 42, a gas distribution plate 43, and a gas transmission hose 44. The inlet of the single-way valve 41 is connected to the air pump 3, the outlet of the single-way valve 41 is connected to the multi-way pipe 42, the other end of the multi-way pipe 42 is respectively provided with a gas distribution plate 43, and the gas distribution plate 43 is connected to the one-way nozzle 52 through the gas transmission hose 44.

[0048] The number of single-way valves 41 is equal to the total number of one-way nozzles 52 on each cracking tube 51 divided by the number of times of opening at a time, and the number of branches of the multi-way pipe 42 is equal to the number of inner cracking tubes 51.

[0049] As Figure 3 shown, the pipe manifold 4 is used for the distribution of gas on each cracking tube 51. Only one cracking tube 51 and a single-way pipe manifold 4 are shown in the figure. When one-third of the jet ports 515 on a single cracking tube 51 are selected to be opened in each pulse cycle, three single-way valves 41 are required for air supply control. The same number of branch pipes as that of the cracking tubes 51 can be connected behind the single-way valves 41. In the previous description, under the working condition of cracking of macromolecular components, the proportion of the opened jet ports 515 each time is reduced, and the number of single-way valves 41 needs to be increased accordingly. Different pipe manifolds 4 with different ratios are replaced according to different working conditions. The gas transmission hose 44 is a metal hose and can withstand the remaining temperature of the environment inside the cracking core.

[0050] Solenoid valves are respectively arranged at the ends of the one-way nozzles 52 far away from the pipe head 511, and the one-way nozzles 52 are uniformly connected to the air pump 3.

[0051] It is also possible to respectively control the intake state at each one-way nozzle 52 by setting more control valves. The disadvantage is that the valves are too close to the hot zone and the number is too large, so the failure rate may increase.

[0052] The cracking furnace further includes a water tank 7, a steam pipe 81, and a return water pipe 82. The water tank 7 is placed beside the cryogenic heat exchanger 6. The water tank 7 supplies cold fluid medium to the cryogenic heat exchanger 6 through a water pump. The cooling medium outlet of the cryogenic 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 water pipe 82.

[0053] As Figure 1 shown, there is a large amount of heat recovery at the cryogenic heat exchanger 6. Conventionally, it is mostly directly used for preheating and temperature raising of raw materials, and there are mainly problems such as uneven cold and heat distribution. In this application, water is added as an intermediate medium for heat transfer to improve the temperature controllability, and the problem of quickly cooling the components after cracking at the cryogenic heat exchanger 6 is mainly improved. 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.

[0054] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in all respects, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes that fall within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. An electric heating cracking furnace with self-regulating function, characterized in that: The cracking furnace includes a feed tank (1), an upper gas pump (3), a pipe manifold (4), a cracking core (5), and an extremely cold heat exchanger (6). A raw material port (19) is provided on the side wall of the feed tank (1). The inlet of the upper gas pump (3) is connected to the feed tank (1), and the outlet of the upper gas pump (3) is connected to the pipe manifold (4). The pipe manifold (4) is divided into several 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 provided on the extremely cold heat exchanger (6). The cracking core (5) includes several cracking tubes (51) arranged inside a housing. The inside of the cracking tubes (51) is in an expanded form, and the raw material to be cracked is thermally cracked inside the cracking tubes (51). The first half of the expanded section inside the cracking tubes (51) is a heating area. The cracking furnace further includes a buffer tank (2). The buffer tank (2) is arranged between the feed tank (1) and the upper gas pump (3), and a temperature control sensor and a heating module are arranged inside the buffer tank (2). 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 housing of the cracking core (5). One end of the tube body (512) is provided with the tube head (511). The end of the tube body (512) far from the tube head (511) is directly connected to the extremely cold heat exchanger (6). A radiation surface (514) is arranged on the inner wall of the tube body (512) near the tube head (511). The tube body (512) gradually expands from the end of the tube head (511). An inner cone (513) is arranged inside the tube head (511) facing the tube body (512). A number of jet orifices (515) distributed in a circumferential pattern are provided on the tube head (511), and the jet orifices (515) are connected to the pipe manifold (4).

2. The self-regulating electric heating cracking furnace according to claim 1, wherein: The jet orifices (515) alternately discharge gas at intervals in a circumferential array pattern.

3. The electrically heated cracking furnace with self-regulating function according to claim 2, wherein: The cracking core (5) further includes a check valve (52). The check valve (52) is arranged at each jet orifice (515). When the medium flows inside the check valve (52), the flow resistance in the direction towards the tube body (512) is less than the reverse flow resistance.

4. The electrically heated cracking furnace with self-regulation function according to claim 3, characterized in that: A number of tapered orifices (521) are axially distributed inside the check valve (52), and the tapered tips face the tube body (512).

5. The electrically heated cracking furnace with self-regulating function according to claim 3, characterized in that: The pipe manifold (4) includes a one-way valve (41), a multi-way pipe (42), a gas distribution plate (43), and a gas transmission hose (44). The inlet of the one-way valve (41) is connected to the upper gas pump (3), 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 respectively provided with a gas distribution plate (43), and the gas distribution plate (43) is connected to the check valve (52) through the gas transmission hose (44). The number of one-way valves (41) is equal to the total number of check valves (52) on each cracking tube (51) divided by the number of times of single opening. The number of branches of the multi-way pipe (42) is equal to the number of inner cracking tubes (51).

6. The electrothermal cracking furnace with a self-regulation function according to claim 3, characterized in that: Solenoid valves are respectively arranged at the ends of the check valves (52) far from the tube head (511), and the check valves (52) are uniformly connected to the upper gas pump (3).

7. The electrically heated cracking furnace with self-regulating function according to claim 3, characterized in that: The cracking furnace further includes a water tank (7), a steam pipe (81), and a water return pipe (82). The water tank (7) is placed beside the cryogenic heat exchanger (6). The water tank (7) supplies a cold flow medium to the cryogenic heat exchanger (6) through a water pump. The cooling medium outlet of the cryogenic heat exchanger (6) is connected to the feed tank (1) through the steam pipe (81). The side wall of the feed tank (1) is connected to the water tank (7) through the water return pipe (82).

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