阅读说明：本技术 一种加热延迟焦化原料的方法 (Method for heating delayed coking raw material ) 是由 罗莹 孙毅 韩艳萍 李昊天 陈海明 冯永生 张伟乾 韩健 袁成志 于 2018-09-06 设计创作，主要内容包括：本公开涉及一种加热延迟焦化原料的方法,该方法包括：使延迟焦化原料作为工艺介质进入加热炉的对流和辐射管内进行加热,工艺介质中催化裂化油浆的重量含量为20～100％,工艺介质中催化剂的重量含量为0.1％～3％,工艺介质在辐射管出口处的压力为0.1～0.8Mpa,温度为460～530℃,气化率为10～60％；辐射管包括螺旋盘管,螺旋盘管的轴向与燃烧器的火焰方向平行。本公开的加热延迟焦化原料的方法采用具有大回转半径螺旋盘管的加热炉辐射管对工艺介质进行加热,能够减小催化油浆中所含催化剂颗粒对炉管及管件的磨损；配合选取的特定工艺介质参数,能够控制工艺介质在炉管中具有适宜的线速度和停留时间、控制加热炉辐射管中热裂化的程度,能够实现加热100％催化油浆,从而提高了延迟焦化的反应效率。(The present disclosure relates to a method of heating a delayed coking feedstock, the method comprising: the delayed coking raw material is used as a process medium to enter a convection and radiation pipe of a heating furnace for heating, the weight content of catalytic cracking slurry oil in the process medium is 20-100%, the weight content of a catalyst in the process medium is 0.1-3%, the pressure of the process medium at the outlet of the radiation pipe is 0.1-0.8 Mpa, the temperature is 460-530 ℃, and the gasification rate is 10-60%; the radiant tube comprises a helical coil, the axial direction of which is parallel to the flame direction of the burner. The method for heating the delayed coking raw material adopts the heating furnace radiant tube with the spiral coil tube with the large turning radius to heat the process medium, so that the abrasion of catalyst particles contained in catalytic slurry oil to a furnace tube and a pipe fitting can be reduced; the selected parameters of the specific process medium are matched, the process medium can be controlled to have proper linear velocity and residence time in the furnace tube, the thermal cracking degree in the radiant tube of the heating furnace is controlled, 100 percent of catalytic slurry oil can be heated, and the reaction efficiency of delayed coking is improved.)

1. A method of heating a delayed coking feedstock, the method comprising: the method comprises the following steps of enabling a delayed coking raw material to serve as a process medium to enter a radiation tube of a heating furnace for heating, wherein the weight content of catalytic cracking slurry oil in the process medium is 20-100%, the weight content of a catalyst in the process medium is 0.1-3%, the pressure of the process medium at an outlet of the radiation tube is 0.1-0.8 Mpa, the temperature is 460-530 ℃, and the gasification rate is 10-60%;

the radiant tube includes a helical coil having an axial direction parallel to a flame direction of the burner.

2. The method of claim 1, wherein the flow pattern of the process media in the radiant tubes comprises stratified flow, wavy flow, liquid throttling, long bubble flow, dispersed bubble flow, annular flow, and mist flow, wherein the length of the liquid throttling is no more than 40% of the total hydraulic length of the helical coil.

3. The method according to claim 1 or 2, wherein the linear velocity of the process medium within the radiant tube is 1-60 m/s.

4. The method of claim 1, wherein the furnace comprises a radiant chamber having a burner and the radiant tube disposed therein; the spiral coil comprises straight pipe sections and bent pipe sections, wherein the straight pipe sections and the bent pipe sections are alternately connected in each spiral unit of the spiral coil to form a waist-shaped shaft section.

5. The method according to claim 4, wherein the bending radius R of the bent pipe section is 300-3000 mm, the ratio of the length of the straight pipe section to the bending radius is (1-30): 1, and the inclination angle β of the spiral coil is 0.1-20 °.

6. A process according to claim 1 or 4, wherein the helical coil has a tube diameter of 76 to 219 mm.

7. The method of claim 1 or 4, wherein the radiant surface heat intensity of the helical coil is 23400-187200 kJ/m²H, the difference of the radiant surface heat intensity of any two spiral units of the spiral coil is not more than 23760kJ/m²·h。

8. The method according to claim 4, wherein the heating furnace is a bottom-burning furnace, the axis of the spiral coil extends in a vertical direction, a first burner group is arranged inside the straight pipe section of the spiral coil, 2 second burner groups are respectively arranged outside the straight pipe section of the spiral coil and are symmetrical to the first burner group, the number of the burners of the first burner group is the same as that of the second burner groups, and the heat load of the first burner group is 2 times that of the second burner groups.

9. The method of claim 1, wherein the heating furnace comprises a convection chamber, a convection pipe communicated with the inlet of the radiant tube is arranged in the convection chamber, the convection pipe comprises a plurality of convection pipe joints which are connected with each other in a zigzag manner at an angle along the axial direction, the included angle between two adjacent convection pipe joints is 5-75 degrees, and the ratio of the pipe diameter of the convection pipe to the pipe diameter of the spiral coil is (0.3-1.5): 1.

10. the method of claim 9, wherein a plurality of convection tubes are arranged in parallel in the convection chamber, inlets and outlets of all the convection tubes are respectively communicated through a collecting tube, and the minimum distance between two adjacent convection tubes is 50-500 mm.

Technical Field

The disclosure relates to the field of petrochemical industry, and in particular relates to a method for heating a delayed coking raw material.

Background

Delayed coking is a thermal cracking process that converts high carbon residue residues to light oils. The apparatus can be operated in a continuous cycle, i.e., the heavier fraction of the heavy oil coking distillate oil is used as the cycle oil, and the residence time in the apparatus is long. The heavy oil is heated to the temperature required by coking reaction by a tubular heating furnace and is quickly separated from the heating furnace tube, the oil is cracked and condensed in a coke tower, the generated oil gas escapes from the top of the coke tower, and the generated coke is left in the tower. In this process, the coking (thermal cracking and condensation) reaction is delayed to the coke drum, hence the term delayed coking.

The content of catalytic slurry oil in the process medium of the existing delayed coking heating furnace is generally controlled to be below 20 percent or lower, and the aim is to control the degree of thermal cracking in a furnace tube of the heating furnace and control the abrasion of catalyst particles contained in the catalytic slurry oil to the furnace tube and a pipe fitting.

The furnace type of the existing delayed coking heating furnace is a single-sided and double-sided radiation vertical furnace (a single-sided radiation diagram 1a, a double-sided radiation diagram 2a, a double-sided radiation diagram 3a and a double-sided radiation diagram 4 a). The heating furnace shown in fig. 1a, fig. 2a, fig. 3a and fig. 4a comprises a radiation section and a convection section, wherein the radiation section is a rectangular hearth 1, the rectangular hearth 1 is divided into two relatively independent combustion chambers by an intermediate partition wall 3 arranged in the rectangular hearth 1 in fig. 1a and fig. 4a, and a tube-side process medium radiation tube 2 is arranged in each relatively independent combustion chamber. The inlet of a typical radiant tube 2 is at the upper part of the end wall of the rectangular furnace 1, the outlet of a typical radiant tube 2 is at the lower part of the end wall of the rectangular furnace 1, the furnace type shown in figure 1a is equipped with a burner 4 only at one side of the radiant tube 2, and the upward flame is generated to supply heat to the radiant tube 2. The furnace type shown in fig. 2a, 3a and 4a is equipped with burners 4 on both sides of the radiant tube 2, generating upward flames to supply heat to the coil 2.

As shown in fig. 1a and 4a, each combustion chamber is provided with two tube-side process media; the radiant tube 2 is in a single-sided radiating arrangement as in fig. 1a, and the radiant tube 2 is in a double-sided radiating arrangement as in fig. 4 a. The common characteristics of the two are that the furnace tubes are arranged from top to bottom in the same plane vertical to the horizontal plane, and the tube center distances h1 and h2 of the sharp bend 6 connecting the furnace tubes are generally 1.75-2 times of the outer diameter of the tube.

As shown in fig. 2a and 3a, each combustion chamber is provided with a tube-side process medium; they have the common features of: the furnace tubes are arranged from top to bottom in the same plane vertical to the horizontal plane, and the tube center distances h1 and h2 of the sharp bend 6 connecting the furnace tubes are generally 1.75-2 times of the outer diameter of the tube.

The common characteristic of the convection section coil pipes shown in fig. 6a and 6b is that the pipe center distance S of the sharp bend 13 connecting the convection section coil pipes is generally 1.75-2 times of the outer diameter of the pipe.

The disadvantages of the above-mentioned furnace types for all-oil slurry media containing metal solid particles are: the pipe center distance of the sharp bend pipe 6 is too small to resist the abrasion of the metal solid phase to the metal wall of the sharp bend pipe 6. If the pipe center distance of the sharp-bent pipe 6 of the radiation section is increased, the height of the vertically arranged radiation section coil pipe 2 is increased, so that the heating nonuniformity along the height direction is increased, the pipe wall temperature nonuniformity is increased, and the coking trend is increased quickly; increasing the tube center distance of the sharp bend of the convection section not only increases the tube bank height, but also increases the convection section width, increases the convection furnace tube distance, reduces the flue gas flow velocity and reduces the heat transfer efficiency for the situation of fig. 6 b. Therefore, the existing heating furnace and the heating method of the catalytic cracking slurry oil can not heat 100 percent of catalytic cracking slurry oil which is not blended.

Disclosure of Invention

It is an object of the present disclosure to provide a process for heating a delayed coking feedstock which is capable of heating a 100% catalytically cracked slurry oil.

To achieve the above object, the present disclosure provides a method of heating a delayed coking feedstock, the method comprising: the method comprises the following steps of enabling a delayed coking raw material to serve as a process medium to enter a radiation tube of a heating furnace for heating, wherein the weight content of catalytic cracking slurry oil in the process medium is 20-100%, the weight content of a catalyst in the process medium is 0.1-3%, the pressure of the process medium at an outlet of the radiation tube is 0.1-0.8 Mpa, the temperature is 460-530 ℃, and the gasification rate is 10-60%; the radiant tube includes a helical coil having an axial direction parallel to a flame direction of the burner.

Optionally, the flow pattern of the process media within the radiant tube comprises at least one of stratified flow, wavy flow, liquid throttling, long bubble flow, dispersed bubble flow, annular flow, and mist flow, wherein the length of the liquid throttling is no more than 40% of the total hydraulic length of the helical coil.

Optionally, the linear velocity of the process medium in the radiant tube is 1-60 m/s.

Optionally, the heating furnace comprises a radiation chamber, and a burner and the radiation pipe are arranged in the radiation chamber; the spiral coil comprises straight pipe sections and bent pipe sections, wherein the straight pipe sections and the bent pipe sections are alternately connected in each spiral unit of the spiral coil to form a waist-shaped shaft section.

Optionally, the bending radius R of the bent pipe section is 300-3000 mm, the ratio of the length of the straight pipe section to the bending radius is (1-30): 1, and the inclination angle β of the spiral coil pipe is 0.1-20 degrees.

Optionally, the diameter of the spiral coil is 76-219 mm.

OptionallyThe heat intensity of the radiation surface of the spiral coil is 23400-187200 kJ/m²H, the difference of the radiant surface heat intensity of any two spiral units of the spiral coil is not more than 23760kJ/m²·h。

Optionally, the heating furnace is a bottom-fired furnace, the shaft of the spiral coil extends upwards along the vertical direction, a first burner group is arranged on the inner side of the straight pipe section of the spiral coil, 2 second burner groups symmetrically arranged with the first burner groups are respectively arranged on the outer side of the straight pipe section of the spiral coil, the number of the burners of the first burner groups is the same as that of the second burner groups, and the heat load of the first burner groups is 2 times that of the second burner groups.

Optionally, the heating furnace includes a convection chamber, a convection pipe communicated with the inlet of the radiant tube is arranged in the convection chamber, the convection pipe includes a plurality of convection pipe joints which are connected with each other at an angle along a polygonal line shape along the axial direction, the included angle between two adjacent convection pipe joints is 5 to 75 degrees, and the ratio of the pipe diameter of the convection pipe to the pipe diameter of the spiral coil pipe is (0.3 to 1.5): 1.

optionally, a plurality of convection tubes are arranged in the convection chamber in parallel, inlets and outlets of all the convection tubes are communicated through a collecting tube respectively, and the minimum distance between two adjacent convection tubes is 50-500 mm.

By adopting the technical scheme, the method for heating the delayed coking raw material adopts the heating furnace radiant tube with the spiral coil to heat the process medium, and the radiant tube has a large turning radius, so that the abrasion of catalyst particles contained in catalytic slurry oil to a furnace tube and a pipe fitting can be reduced; meanwhile, the height of the tube bank of the heating furnace is controllable, and the tube bank is uniformly heated by radiation along the height direction of the tube bank. The method can control the process medium to have proper linear velocity and residence time in the furnace tube and control the thermal cracking degree in the radiant tube of the heating furnace by matching with the selected specific process medium parameters, greatly improve the content of catalytic slurry oil in the process medium, and can heat the delayed coking raw material containing 100 percent of catalytic cracking slurry oil.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

FIG. 1a is a front view of a single-sided radiation coking furnace.

FIG. 1b is a top view of a single-sided radiation coking furnace.

FIG. 2a is a front view of a double-sided radiation coking furnace.

FIG. 2b is a top view of a double-sided radiation coking furnace.

FIG. 3a is a front view of another double-sided radiation coke oven.

FIG. 3b is a top view of another double-sided radiation coking furnace.

FIG. 4a is a front view of a third double-sided radiation coking furnace.

FIG. 4b is a top view of a third double-sided radiation coking furnace.

Fig. 5a is a front view of a furnace radiant chamber of one embodiment of the delayed coking process of the present disclosure.

Figure 5b is a top view of a furnace radiant chamber of one embodiment of the delayed coking process of the present disclosure.

Figure 5c is a top view of a furnace radiant chamber of another embodiment of the delayed coking process of the present disclosure.

Fig. 6a is a schematic view of a convection tube of a furnace.

Fig. 6b is a schematic view of another furnace convection tube.

Fig. 6c is a schematic view of a furnace convection tube of an embodiment of the delayed coking process of the present disclosure.

Fig. 6d is a schematic view of a furnace convection tube of another embodiment of the delayed coking process of the present disclosure.

Description of the reference numerals

1. A rectangular hearth; 2. a radiant tube; 3. a middle partition wall; 4. a burner; 41. a second burner group; 42. a first burner group; 5. a convection section; 6. bending the pipe sharply; 7. a straight pipe section; 8. bending the pipe section; 9. a radiant tube rack; 10. a radiation chamber; 11. a high temperature flue; 12. a convection chamber; 13. bending a pipe in a sharp bend at the convection section; 14. a convection tube; 15. a convection pipe section; 161. a manifold; 162. a manifold.

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

In the present disclosure, unless otherwise stated, the use of directional terms such as "up" and "down" generally refers to up and down of the device in normal use, and specifically refers to the direction of the drawing of fig. 5 a. The "inner and outer" are with respect to the outline of the device itself.

The present disclosure provides a method of heating a delayed coking feedstock, the method comprising: the delayed coking raw material is used as a process medium to enter a radiant tube of a heating furnace for heating, the weight content of catalytic cracking slurry oil in the process medium is 20-100%, the weight content of a catalyst in the process medium is 0.1-3%, the pressure of the process medium at the outlet of the radiant tube is 0.1-0.6 Mpa, the temperature is 460-530 ℃, and the gasification rate is 10-60%; the radiant tube comprises a helical coil, the axial direction of which is parallel to the flame direction of the burner.

Compared with the common radiant tube, the spiral radiant tube has large radius of gyration, and can reduce the abrasion of catalyst particles contained in catalytic cracking slurry oil on a furnace tube and a pipe fitting; meanwhile, the height of the tube bank of the heating furnace is controllable, the tube bank uniformly receives thermal radiation along the height direction of the tube bank, and the selected parameters of the specific process medium are matched, so that the process medium can be controlled to have proper linear speed and residence time in the furnace tube, the thermal cracking degree in the radiant tube of the heating furnace can be controlled, the content of catalytic slurry oil in the process medium can be greatly improved, the delayed coking raw material containing 100% of catalytic cracking slurry oil can be heated, and the reaction efficiency of delayed coking is improved.

In the delayed coking method according to the present disclosure, the meaning of the process medium is well known to those skilled in the art, that is, the medium heated in the furnace tube of the heating furnace, that is, the raw material for delayed coking, in the present disclosure, the process medium may include catalytic cracking slurry oil, and the content of the catalytic cracking slurry oil may be 20 to 100%, for example, 50 to 100% of the catalytic cracking slurry oil, and further preferably 100% of the catalytic cracking slurry oil; the process medium may also include a catalytic cracking catalyst and the balance resid and/or cycle oil. The flow pattern of the process medium within the radiant tube may comprise at least one of stratified flow, wavy flow, liquid throttling, long bubble flow, dispersed bubble flow, annular flow and mist flow, preferably stratified flow, wavy flow, liquid throttling, long bubble flow, dispersed bubble flow, annular flow and mist flow; wherein, in order to control the gasification rate of the process medium in a proper range, the length of the liquid throttling is preferably not more than 40% of the total hydraulic length of the spiral coil.

In the delayed coking method, in order to enable the process medium to have a more proper linear velocity in the radiant tube and further control the thermal cracking degree of the process medium in the heating furnace tube, the pressure of the process medium at the outlet of the radiant tube is further preferably 0.2-0.5 Mpa, the temperature is preferably 465-525 ℃, and the gasification rate is preferably 15-55%.

In the delayed coking method, the process medium has a proper high linear velocity in the radiant tube, so that the retention time of the process medium in the heating furnace tube can be ensured to be short, the catalytic slurry oil is prevented from coking in the heating furnace tube, and the linear velocity of the process medium in the radiant tube can be 1-60 m/s, preferably 2-55 m/s, and further preferably 15-50 m/s. Wherein the linear velocity of the process medium within the radiant tube is referred to as the average linear velocity.

According to the present disclosure, the shape and kind of the heating furnace may be conventional in the art, for example, as shown in fig. 5a and 5b, the heating furnace may include a radiation chamber 10, the radiation chamber 10 may be provided with a burner 4 and a radiation pipe, the radiation pipe may include the above-mentioned spiral coil, i.e., at least a portion of the radiation pipe may be formed in a spiral coil shape, the radiation pipe may further include a connection pipe for connecting the spiral coil and the convection pipe, the shape of the connection pipe is not particularly limited, and the length of the spiral coil may account for more than 80% of the total length of the radiation pipe, so as to further increase the heating effect of the radiation pipe; the spiral coil pipes in the radiation chamber can be arranged in a single way or connected in parallel in multiple ways; the spiral coil may be formed as a coil having a circular, oval or kidney-shaped axial cross section, preferably, the spiral coil has a kidney-shaped axial cross section as shown in fig. 5b, and in this embodiment, further, the spiral coil may include a straight pipe section 7 and a bent pipe section 8, and in each spiral unit of the spiral coil, the straight pipe section 7 and the bent pipe section 8 are alternately connected to form the kidney-shaped axial cross section, wherein the spiral unit refers to a pipe unit formed by winding the spiral coil by one turn, and in the kidney-shaped axial cross section spiral coil, one spiral unit generally includes two straight pipe sections and two bent pipe sections which are alternately connected.

Further, in order to reduce the abrasion of the solid catalyst particles in the process medium to the pipe fittings, the bend section 8 of the spiral coil pipe can have a larger bending radius R, preferably, the bending radius R of the bend section 8 is 300-3000 mm, and more preferably 350-2800 mm; the ratio of the length of the straight pipe section 7 to the bending radius of the bent pipe section 8 can be (1-30): 1, preferably (2.5-10): 1; in the preferable pipe parameter range, the bending radius of the bent pipe section of the spiral coil pipe is proper, on one hand, the abrasion to a metal wall when a medium in the pipe turns can be reduced, on the other hand, the bent pipe section with a large radius is adopted as a rotary elbow of the spiral coil pipe, the inner surface area and the outer surface area are close, the peak value of the pipe wall temperature of the radiant pipe is favorably stabilized under the condition of double-sided heat radiation, the uniformity of the pipe wall temperature distribution of the radiant pipe is increased, and the coking tendency in the pipe is reduced.

Further, in order to ensure uniform radiation heat supply of the process medium along the height direction of the tube rows, the inclination angle β of the spiral coil can be 0.1-20 degrees, and is further preferably 0.2-18 degrees, wherein the inclination angle of the spiral coil refers to the included angle between the plane of each spiral unit of the spiral coil and the section perpendicular to the shaft.

According to the present disclosure, the diameter of the spiral coil can be varied within a wide range, preferably 76-219 mm, and more preferably 80-200 mm, within the preferable range, the process medium in the spiral coil can be uniformly heated, and the flow rate and the gasification rate of the process medium can be maintained within a more suitable range.

According to the present disclosure, the radiant surface heat intensity of the spiral coil can be varied over a wide range, and preferably, the radiant surface heat intensity of the spiral coil can be 23400-187200 kJ/m²H, further preferably 39600 to 172000kJ/m²H, within the preferred radiant surface heat intensity range described above, the spiral coil has a suitable heat transfer rate without causing localized overheating or coking of the furnace tubes.

Further, in order to control the height of the tube row of the heating furnace within a suitable range, it is preferable that the difference in the radiant surface heat intensity of any two spiral units of the spiral coil does not exceed 23760kJ/m²H to ensure uniform radiant heating along the tube row height. The meaning of radiant surface heat intensity is well known to those skilled in the art, i.e., the amount of heat transferred per unit area (outer surface) of the radiant furnace tube per unit time can be calculated by methods conventional in the art. The radiant surface heat intensity of each single furnace tube is obtained by dividing the surface area of each furnace tube by the heat absorbed by each furnace tube, the radiant surface heat intensity of each furnace tube is usually different, the radiant surface heat intensity of each spiral unit (namely, each circle of the spiral coil) in the spiral coil disclosed by the disclosure is also different, and in the disclosure, preferably, the difference value of the radiant surface heat intensity of any two spiral units of the spiral coil is not more than 23760kJ/m²H, i.e. the difference between the spiral unit with the maximum radiant surface heat intensity and the spiral unit with the minimum radiant surface heat intensity does not exceed 23760kJ/m²·h。

According to the present disclosure, the heating furnace may be of a conventional type in the art, and is preferably a bottom-fired furnace, the spiral coil is arranged in a vertical direction, the flame of the burner of the heating furnace extends upward from the bottom, the spiral coil extends upward spirally with the vertical direction as an axis, and the spiral coil in the radiation chamber may be set to be connected in parallel in one way or multiple ways. The burner may form a vertical upward circular flame, a vertical upward flat flame or a coanda flat flame.

Further, in order to ensure uniform heating inside and outside the spiral coil, in an embodiment of the present disclosure, as shown in fig. 5b, a first burner group 42 may be disposed inside the straight tube section of the spiral coil, 2 second burner groups 41 symmetrically disposed with respect to the first burner group 42 may be disposed outside the straight tube section 7 of the spiral coil, the number of burners of the first burner group 42 and the second burner group 41 is preferably the same, further preferably, the burners of the first burner group 42 and the second burner group 41 are disposed correspondingly, that is, the straight tube section 7 is disposed axially symmetrically, and the heat load of the first burner group 42 is preferably 2 times the heat load of the second burner group 41. The inner side and the outer side of the straight pipe section are defined by the spiral coil, one side close to the axis of the coil is the inner side, and one side far away from the axis and close to the wall of the radiation chamber is the outer side. In the embodiment, the radiant tubes in the radiant chamber adopt a symmetrical double-sided radiation heat supply mode, so that the heating nonuniformity generated in the circumferential direction of the tube row by single-sided radiation or asymmetrical double-sided radiation can be avoided, the peak value of the temperature along the tube wall of the furnace tube is favorably stabilized, the uniformity of the temperature distribution of the circumferential tube wall of the furnace tube is increased, the coking tendency is reduced, and the service life of the furnace tube is prolonged.

As an embodiment of the present disclosure, as shown in fig. 5b, the inner burner (i.e., the first burner group 42) surrounded by the radiant tubes and the outer burner (i.e., the second burner group 41) surrounded by the radiant section coils respectively adopt vertically upward flat flame burners, and the burner flames of the first burner group 42 and the second burner group 41 have the same width, length and height, and the heat load of the first burner group 42 is 2 times that of the second burner group 41, so that symmetrical double-sided radiation is formed for the tube rows.

In another embodiment of the present disclosure, as shown in fig. 5c, the spiral coil is formed as a spiral coil with a circular axial cross-section, the inner side of the spiral coil is provided with a first burner group 42, the outer side is provided with a second burner group 41, the first burner group 42 and the second burner group 41 have the same thermal load, the flame diameter and the height are the same, and the tube rows are completely symmetrical and double-sided radiation is formed.

In one embodiment of the present disclosure, the radiant tubes may be fixed to a support frame, which is preferably a cast tube frame.

According to the present disclosure, the furnace may further include a convection chamber, in which convection tubes may be provided in communication with inlets of the radiant tubes, which may be of a type conventional in the art. In a preferred embodiment of the present disclosure, as shown in fig. 6c, the convection tube may include a plurality of convection tube sections 15 connected to each other at an angle in a zigzag shape along the axial direction, an included angle between two adjacent convection tube sections 15 may be 5 to 75 °, preferably 8 to 70 °, and a ratio of a tube diameter of the convection tube to a tube diameter of the spiral coil may be (0.3 to 1.5): 1, preferably (0.5-1): 1, two adjacent convection tube joints 15 can be connected through the return bend, and in this embodiment, the convection tube that adopts the form of buckling to connect can increase the turn angle degree of technology medium in the pipe, reduces the wearing and tearing of technology medium to the pipeline, and its heat transfer efficiency is higher simultaneously, has avoided increasing the bank of tubes height that the pipe interval caused and has increased, the problem that the flue gas velocity of flow descends.

Further, as shown in fig. 6d, a plurality of convection tubes may be connected in parallel in the convection chamber, inlets and outlets of all convection tubes may be respectively communicated through a collecting tube, a minimum distance between two adjacent convection tubes may be 50 to 500mm, preferably 60 to 450mm, and a flue gas flow rate in the convection chamber may be maintained at 0.3 to 4kg/m at this time²s to ensure heat transfer efficiency to the convection tubes.

According to the present disclosure, the heating furnace may include one or more radiation chambers, the radiation chambers may be connected by a cross beam and respectively communicated to the convection chamber, and each radiation chamber may be correspondingly communicated with one or more convection chambers.

The method for heating delayed coking feedstock of the present disclosure may be used in a delayed coking process, which may include a step of feeding a process medium obtained at an outlet of a heating furnace tube into a coke drum for cracking and condensation coke formation reactions, and methods and conditions of the step may be conventional in the art and will not be described herein again.