Cracking furnace temperature difference control system and method, cracking furnace and machine readable storage medium

Abstract

Embodiments of the present application provide a pyrolysis furnace temperature difference control system, method, pyrolysis furnace and machine readable storage medium, belong to automatic control technical field.The pyrolysis furnace temperature difference control system includes: a plurality of control valves, corresponding to the number of radiation section pyrolysis gas outlet groups of the pyrolysis furnace, each control valve is used to control the flow of a group of side wall fuel gas nozzles;Controller is used to calculate the difference between the COT average value of each group of furnace tubes and the COT average value of all furnace tubes respectively, and adjusts the opening of the corresponding control valve according to the difference, so that the radiation section outlet temperature COT of each group of furnace tubes is consistent. Wherein, the side wall fuel gas nozzle of the pyrolysis furnace is grouped according to the number of radiation section pyrolysis gas outlet groups.The control system can automatically adjust the flow of the side wall fuel gas nozzle, so that the radiation section outlet temperature COT of each group of furnace tubes is consistent, and the coking rate of each group of furnace tubes is consistent.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology, and more specifically to a temperature difference control system, method, pyrolysis furnace, and machine-readable storage medium for a pyrolysis furnace. Background Technology

[0002] In existing technologies, the feed rate of each group in a cracking furnace is controlled in a cascade manner. The total feed flow controller outputs a setpoint to each group's feed controller. Then, the temperature difference controller (TDC) equipped in each group of furnace tubes corrects the corresponding feed rate of each group based on the setpoint. The corrected value is used as the final setpoint for each group's feed controller. That is, within the allowable deviation range of the radiant section outlet temperature of each group, the radiant section outlet temperature (COT) of each group of furnace tubes is kept consistent by adjusting the feed rate of each group. Summary of the Invention

[0003] In the process of realizing this invention, the inventors of this application discovered that the above-mentioned solution in the prior art, which controls TDC by the amount of each group of raw materials, will cause the flow rate in each group of furnace tubes to be inconsistent for a long time, resulting in inconsistent coking degree in each group of furnace tubes and affecting the long-term stable operation of the cracking furnace. On the other hand, when the number of raw material groups entering the cracking furnace and the number of cracking gas groups exiting the radiation section are inconsistent, the amount of raw materials in each group cannot be adjusted in a one-to-one correspondence manner to make the outlet temperature of the radiation section of each group of furnace tubes consistent.

[0004] The purpose of this invention is to provide a control system that controls the flow rate of fuel gas on the sidewalls of each group of furnace tubes, so that the outlet temperature (COT) of the radiant section of each group of furnace tubes is consistent.

[0005] To achieve the above objectives, embodiments of the present invention provide a temperature difference control system for a pyrolysis furnace, comprising: multiple control valves, configured corresponding to the number of groups of pyrolysis gas outlets in the radiant section of the pyrolysis furnace, each control valve controlling the flow rate of a group of sidewall fuel gas nozzles; and a controller, configured to calculate the difference between the average COT of each group of furnace tubes and the average COT of all furnace tubes, and adjust the opening of the corresponding control valve according to the difference, so that the radiant section outlet temperature COT of each group of furnace tubes is consistent. The sidewall fuel gas nozzles of the pyrolysis furnace are grouped according to the number of pyrolysis gas outlet groups in the radiant section.

[0006] The control system automatically adjusts the flow rate of each group of sidewall fuel gas nozzles through control valves. The control valves are set according to the number of groups of pyrolysis gas outlets in the radiant section of the pyrolysis furnace, and can adjust the radiant section outlet temperature (COT) of each group of furnace tubes one by one, so that the radiant section outlet temperature (COT) of each group tends to be consistent. On the other hand, since the pyrolysis furnace temperature difference control system of the present invention does not differentiate the raw material flow rate of each group, it can ensure that the coking rate of each group of furnace tubes is consistent when the raw material supply of each group tends to be consistent.

[0007] Preferably, the feed rate of each group of furnace tubes is controlled in cascade by the total feed rate controller of the pyrolysis furnace, so that the feed rate of each group of furnace tubes is the same.

[0008] Preferably, the controller is also used to transmit the average COT of all furnace tubes to the bottom fuel gas controller of the cracking furnace to adjust the bottom fuel gas quantity.

[0009] Preferably, the controller adjusts the opening of the corresponding control valve based on the higher of the difference between each group of furnace tubes and a preset minimum value.

[0010] Preferably, the average COT of each group of furnace tubes is calculated using the following formula:

[0011] R t =ΣA i / N, (i = 1, 2, 3, ..., N),

[0012] Among them, R t Let A be the average COT of the furnace tubes in group t. i This represents the COT value of the i-th furnace tube in the t-th group of furnace tubes, and N is the number of furnace tubes in the t-th group of furnace tubes. If the COT value of a single furnace tube is bad, it is not included in the count.

[0013] The average COT of all furnace tubes is calculated using the following formula:

[0014] R M =ΣR t / M, (t=1,2,3…,M)

[0015] Among them, R M R is the average COT of all furnace tubes. t Let COT be the average value of the t-th group of furnace tubes, and M be the total number of groups of furnace tubes.

[0016] On the other hand, the present invention provides a method for controlling the temperature difference in a pyrolysis furnace. The sidewall fuel gas nozzles of the pyrolysis furnace are grouped according to the number of pyrolysis gas outlet groups in the radiant section. Multiple control valves are set corresponding to the number of pyrolysis gas outlet groups in the radiant section of the pyrolysis furnace. Each control valve is used to control the flow rate of a group of sidewall fuel gas nozzles to adjust the radiant section outlet temperature (COT) of the corresponding group of furnace tubes. The method includes:

[0017] Calculate the difference between the average COT of each group of furnace tubes and the average COT of all furnace tubes;

[0018] Adjust the opening degree of the corresponding control valve according to the difference in value for each group of furnace tubes.

[0019] Preferably, the feed rate of each group of furnace tubes is controlled in cascade by the total feed rate controller of the pyrolysis furnace, so that the feed rate of each group of furnace tubes is the same.

[0020] Preferably, the average COT value of all furnace tubes is transmitted to the bottom fuel gas controller of the pyrolysis furnace to adjust the bottom fuel gas quantity.

[0021] Preferably, the opening degree of the corresponding control valve is adjusted according to the higher of the difference between each group of furnace tubes and a preset minimum value.

[0022] Preferably, the average COT of each group of furnace tubes is calculated using the following formula:

[0023] R t =ΣA i / N, (i = 1, 2, 3, ..., N),

[0024] Among them, R t Let A be the average COT of the furnace tubes in group t. i This represents the COT value of the i-th furnace tube in the t-th group of furnace tubes, and N is the number of furnace tubes in the t-th group of furnace tubes. If the COT value of a single furnace tube is bad, it is not included in the count.

[0025] The average COT of all furnace tubes is calculated using the following formula:

[0026] R M =ΣR t / M, (t=1,2,3…,M)

[0027] Among them, R M R is the average COT of all furnace tubes. t Let COT be the average value of the t-th group of furnace tubes, and M be the total number of groups of furnace tubes.

[0028] On the other hand, the present invention provides a pyrolysis furnace, including the pyrolysis furnace temperature difference control system of this application.

[0029] On the other hand, the present invention provides a machine-readable storage medium storing instructions for causing a machine to perform the method of pyrolysis furnace temperature difference control of the present application.

[0030] Through the above technical solution, multiple control valves are set according to the number of groups of pyrolysis gas outlets in the radiant section of the pyrolysis furnace. The flow rate of fuel gas on the side wall of each group is automatically adjusted by the multiple control valves. The radiant section outlet temperature (COT) of each group of furnace tubes can be adjusted one by one and made to be consistent. The present invention does not require different control of the raw material flow rate of each group. When the raw material supply of each group is consistent, it can ensure that the coking rate of each group of furnace tubes is consistent.

[0031] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0032] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0033] Figure 1 This is a structural diagram of the temperature difference control system for a pyrolysis furnace in the prior art;

[0034] Figure 2 This is a structural diagram of one embodiment of the pyrolysis furnace temperature difference control system of this application;

[0035] Figure 3 This is a schematic diagram of a set of furnace tubes in a pyrolysis furnace of existing technology;

[0036] Figure 4 This is a schematic diagram of a group of furnace tubes in one embodiment of the pyrolysis furnace temperature difference control system of this application; and

[0037] Figure 5 This is a flowchart of one embodiment of the pyrolysis furnace temperature difference control method of this application. Detailed Implementation

[0038] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0039] In existing technologies, pyrolysis furnaces typically employ, for example... Figure 1 The temperature difference control system shown ensures consistent radiant section outlet temperatures (COT) for each group of furnace tubes by adjusting the raw material feed rate within the allowable range of temperature deviation at the outlet of each radiant section. Figure 1 The diagram shows four groups for raw material feed control and six groups for fuel gas nozzles. This is only to illustrate that the raw material feed grouping, pyrolysis gas outlet grouping (not shown), and fuel gas feed grouping of the cracking furnace are not one-to-one correspondences, and are not strictly limited to this in practice. Figure 1 In the illustrated embodiment, the feed rate of each group of the cracking furnace is controlled in cascade. A setpoint is output by the total feed rate controller, and each group's feed rate controller can use this setpoint to directly control the feed rate of its corresponding group. To ensure that the radiant section outlet temperature (COT) of each group of furnace tubes is consistent, each group of furnace tubes is equipped with a temperature difference controller (TDC). The setpoint output by the total feed rate controller is positively or negatively corrected, and the corrected value is used as the final setpoint for each group's feed rate controller.

[0040] However, due to the inconsistency between the number of raw material groups and the number of pyrolysis gas groups exiting the radiation section, the existing technology cannot achieve one-to-one adjustment of the outlet temperature of the radiation section by adjusting the raw material quantity. Furthermore, TDC control by adjusting the raw material quantity of each group will cause the flow rate in each group of furnace tubes to be inconsistent for a long time, resulting in inconsistent coking degree of each group of furnace tubes, which affects the long-term operation of the pyrolysis furnace.

[0041] To address the aforementioned problems, the inventors proposed a pyrolysis furnace temperature difference control system based on the radiation section outlet temperature (COT). For example... Figure 2 In one embodiment of the system shown, multiple control valves are configured corresponding to the number of pyrolysis gas outlet groups in the radiant section of the pyrolysis furnace. Each control valve controls the flow rate of a group of sidewall fuel gas nozzles. The controller calculates the difference between the average COT of each group of furnace tubes and the average COT of all furnace tubes, and adjusts the opening of the corresponding control valve based on this difference. In this embodiment, the sidewall fuel gas nozzles of the pyrolysis furnace are grouped according to the number of pyrolysis gas outlet groups in the radiant section. The control valves control the fuel gas flow rate output by the sidewall fuel gas nozzles, affecting the fuel gas supply in each group of furnace tubes, thereby making the radiant section outlet temperature (COT) of each group of furnace tubes tend to be consistent.

[0042] It should be noted that the COT temperature difference control implemented in this embodiment can directly use the set value output by the total raw material flow controller to control the feed rate of each group of raw materials, without the need for fine-tuning the feed rate of each group of raw materials through the temperature difference controller (TDC) or other methods. Therefore, in some embodiments, the feed rate of each group of furnace tubes is controlled in cascade by the total raw material flow controller of the cracking furnace to ensure that the feed rate of each group of furnace tubes is the same.

[0043] In some embodiments, the controller is also used to transmit the average COT of all furnace tubes to the bottom fuel gas controller of the pyrolysis furnace to adjust the bottom fuel gas quantity.

[0044] In some implementations, the controller adjusts the opening of the corresponding control valve based on the higher of the difference between each group of furnace tubes and a preset minimum value.

[0045] In some embodiments, the average COT of each group of furnace tubes is calculated using the following formula:

[0046] R t =ΣA i / N, (i = 1, 2, 3, ..., N),

[0047] Among them, R t Let A be the average COT of the furnace tubes in group t. iThis represents the COT value of the i-th furnace tube in the t-th group of furnace tubes, and N is the number of furnace tubes in the t-th group of furnace tubes. If the COT value of a single furnace tube is bad, it is not included in the count.

[0048] The average COT of all furnace tubes is calculated using the following formula:

[0049] R M =ΣR t / M, (t=1,2,3…,M)

[0050] Among them, R M R is the average COT of all furnace tubes. t Let COT be the average value of the t-th group of furnace tubes, and M be the total number of groups of furnace tubes.

[0051] The advantages of this embodiment compared with the prior art are: (1) Multiple control valves are set according to the number of groups of pyrolysis gas outlets in the radiant section of the pyrolysis furnace, which can feed back the radiant section outlet temperature of each group of furnace tubes to control the sidewall fuel gas flow rate of each group, so that the radiant section outlet temperature of each group tends to be consistent; (2) The raw material total flow controller outputs a unified set value to the raw material feed controller of each group, so that the raw material flow rate of each group is the same, thereby ensuring that the coking rate of each group of furnace tubes is consistent.

[0052] To better illustrate the differences between the pyrolysis furnace temperature difference control system of this application and the prior art, the following is combined with... Figure 3 and Figure 4 This paper introduces the methods for temperature difference control in a pyrolysis furnace using existing technologies and the technical solutions of this invention, respectively. Figure 3 and Figure 4 Each group shows a set of furnace tubes and their associated components; the control methods for other groups are the same as those shown.

[0053] exist Figure 3 The diagram shows the first group of multiple furnace tubes in a prior art embodiment. The pyrolysis furnace uses four feed groups, each equipped with a control valve to control the flow rate of the raw materials. In this illustrated group, the feed is first based on furnace A (i.e., Figure 3 The initial setpoint input to the raw material total feed rate regulator FIC0X000 (showing the furnace corresponding to the furnace tube) is then corrected by the summation calculation module FY0X011, which calculates the OP value (output value) of the raw material total feed rate regulator in furnace A and the OP value of the first group of temperature difference regulators, to obtain the final setpoint. This final setpoint is then transmitted to the first group of raw material flow rate regulators FIC0X011, which ultimately controls the opening of the raw material control valve. It should be noted that in... Figure 3In the illustrated embodiment, the flow rate of the sidewall fuel gas is controlled by the first set of average COTTY0X011 values, and the values ​​of different sets are input from the four sets of average COTTY0X000 values ​​of furnace A. That is to say, in the prior art, by controlling the supply of raw materials for different sets separately, the radiant section outlet temperature COT of each set of furnace tubes tends to be consistent.

[0054] like Figure 4 The diagram shows the first group of multiple furnace tubes in an embodiment of the pyrolysis furnace temperature difference control system of the present invention. Unlike existing embodiments that control the supply of raw materials to each group of furnace tubes, this embodiment adds a control valve to each group of furnace tubes to control the flow rate of fuel gas. In the illustrated group, the newly added control valve is the sidewall fuel gas pressure control valve PV09180. This control valve controls its opening size based on the pressure value calculated and transmitted by the sidewall fuel gas pressure selector calculation module PY09180, thereby controlling the supply of fuel gas in the furnace tubes.

[0055] It should be noted that the side wall fuel gas pressure controller PIC09180 and the temperature difference controller TDIC09011 are the two inputs to the side wall fuel gas pressure high selector calculation module PY09180. PY09180 outputs the higher of the two input values. The value of the side wall fuel gas pressure controller PIC09180 is a preset value based on experience. This preset value is used to control the opening of the side wall fuel gas pressure control valve PV09180 to ensure that the fuel gas supply is not lower than the minimum empirical value. The value of the temperature difference controller TDIC09011 is determined through calculation. Figure 4 As shown, the average COT calculation module TY09011 is used to calculate the average COT of the furnace tubes in this group, the overall average COT calculation module TY09000 is used to calculate the average COT of all furnace tubes, and the temperature difference regulation controller TDIC09011 is used to calculate the control value in real time based on the difference between the average COT of the furnace tubes in this group and the average COT of all furnace tubes. This control value can directly control the opening of the side wall fuel gas pressure control valve PV09180, or control the opening of the side wall fuel gas pressure control valve PV09180 after passing through the side wall fuel gas pressure high selector calculation module PY09180.

[0056] Figure 4 Only one group of furnace tubes is shown. The other groups are also equipped with control valves to control the fuel gas flow rate. These control valves are also adjusted in real time based on the difference between the average COT (Coking Temperature) of the current group and the average COT of all furnace tubes. Ultimately, by controlling the fuel gas supply to different groups, the radiant section outlet temperature (COT) of each group of furnace tubes is made more consistent. Furthermore, this invention does not require controlling the raw material supply to different groups; with the same raw material flow rate in each group, the coking rate of each group of furnace tubes is consistent.

[0057] Further explanation is as follows: Figure 4 The overall situation of the embodiment of the present invention is shown. The single-furnace pyrolysis furnace F-009 in this embodiment adopts four groups of feed. After the raw material enters the convection section, it is further divided into eight groups to save investment in regulating valves and pipelines. The convection section coils are merged into two distribution pipes at the cross section. Each distribution pipe is directly divided into three groups through the Venturi into the 2-1 type radiation section. Each group has 28 single-pass tubes. The radiation section exits with 14 double-pass tubes per group, for a total of six groups. Each furnace tube in the radiation section is equipped with a wall-mounted thermocouple. The real-time value of the thermocouple is transmitted to the DCS system as the input process value for the controller of the pyrolysis furnace outlet temperature. The average COT (TY09011~6) of each group can be calculated through the DCS logic.

[0058] Taking the first group as an example, the average COT(TY09011) of this group is calculated as follows:

[0059] TY09011=ΣAi / 14,

[0060] Ai = TT09011A ~ N(PV);

[0061] If a single furnace tube with a defective COT value needs to be removed, the formula is as follows:

[0062] TY09011=Σ(Ai*Si) / Σ(Si),

[0063] In the formula:

[0064] Ai = TT09011A ~ N(PV);

[0065] Si = TT09011A ~ N good values ​​(0 = bad value; 1 = good value).

[0066] After calculating the average COT of the six groups (TY09011~6), the total COT of the cracking furnace (TY09000) is obtained by averaging the values ​​through DCS logic. The calculation formula is as follows:

[0067] TY09000=ΣRt / 6

[0068] Rt = TY09011~6 (average COT for each group);

[0069] The TY09000 value, representing the real-time total COT of the pyrolysis furnace, is transmitted to the calculation module of each group of furnace tubes. This value is compared with the set total COT value of the pyrolysis furnace and then transmitted to the bottom fuel gas controller to adjust the bottom fuel gas flow and control the total COT of the pyrolysis furnace. Each group's temperature difference regulator TDIC09011-6 controls the opening of the side wall fuel gas pressure control valve based on the difference between the group's average COT (TY090011-6) and the total COT value. TDIC09011-6 can also transmit the value to the corresponding group's side wall fuel gas pressure control valve via a side wall fuel gas pressure selector, adjusting the corresponding group's side wall fuel gas flow to eliminate deviations in the COT (TY09011-6) of each group, ensuring consistent radiant section outlet temperature (COT) for each group of furnace tubes.

[0070] This invention provides a method for controlling the temperature difference in a pyrolysis furnace. This method can be applied to any of the pyrolysis furnace temperature difference control systems and pyrolysis furnaces described in this invention. The control method is as follows: Figure 5 As shown, it includes:

[0071] First, calculate the difference between the average COT of each group of furnace tubes and the average COT of all furnace tubes;

[0072] Then, the opening degree of the corresponding sidewall fuel gas control valve is adjusted according to the difference in value for each group of furnace tubes.

[0073] The sidewall fuel gas nozzles of the pyrolysis furnace are grouped according to the number of pyrolysis gas outlet groups in the radiant section. The same number of control valves are set up to correspond to the number of pyrolysis gas outlet groups in the radiant section of the pyrolysis furnace. Each control valve is used to control the flow rate of a group of sidewall fuel gas nozzles to adjust the radiant section outlet temperature COT of the corresponding group of furnace tubes.

[0074] In some embodiments, the feed rate of each group of furnace tubes is controlled in cascade by the feed total flow controller of the pyrolysis furnace, so that the feed rate of each group of furnace tubes is the same.

[0075] In some implementations, the average COT value of all furnace tubes is transmitted to the bottom fuel gas controller of the pyrolysis furnace to regulate the bottom fuel gas quantity.

[0076] In some implementations, the opening of the corresponding sidewall fuel gas control valve is adjusted based on the higher of the difference between each group of furnace tubes and a preset minimum value.

[0077] In some embodiments, the average COT of each group of furnace tubes is calculated using the following formula:

[0078] R t =ΣA i / N, (i = 1, 2, 3, ..., N),

[0079] Among them, R tLet A be the average COT of the furnace tubes in group t. i This represents the COT value of the i-th furnace tube in the t-th group of furnace tubes, and N is the number of furnace tubes in the t-th group of furnace tubes. If the COT value of a single furnace tube is bad, it is not included in the count.

[0080] The average COT of all furnace tubes is calculated using the following formula:

[0081] R M =ΣR t / M, (t=1,2,3…,M)

[0082] Among them, R M R is the average COT of all furnace tubes. t Let COT be the average value of the t-th group of furnace tubes, and M be the total number of groups of furnace tubes.

[0083] This invention provides a pyrolysis furnace, including the pyrolysis furnace temperature difference control system of this application.

[0084] This invention provides a machine-readable storage medium storing program instructions that cause a machine to execute the method for controlling the temperature difference of a pyrolysis furnace as described in this application.

[0085] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0086] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A temperature difference control system for a pyrolysis furnace, characterized in that, include: Multiple control valves are set according to the number of groups of pyrolysis gas outlets in the radiant section of the pyrolysis furnace. Each control valve is used to control the flow rate of a group of sidewall fuel gas nozzles. as well as The controller is used to calculate the difference between the average COT of each group of furnace tubes and the average COT of all furnace tubes, and adjust the opening of the corresponding control valve according to the difference to ensure that the COT of the radiant section outlet of each group of furnace tubes is consistent. Among them, the side wall fuel gas nozzles of the pyrolysis furnace are grouped according to the number of pyrolysis gas outlet groups in the radiation section.

2. The system according to claim 1, characterized in that, The feed rate of each group of furnace tubes is controlled in cascade by the feed rate controller of the pyrolysis furnace to ensure that the feed rate of each group of furnace tubes is the same.

3. The system according to claim 1, characterized in that, The controller is also used to transmit the average COT of all furnace tubes to the bottom fuel gas controller of the cracking furnace to adjust the bottom fuel gas quantity.

4. The system according to claim 1, characterized in that, The controller adjusts the opening of the corresponding control valve based on the higher of the difference between each group of furnace tubes and a preset minimum value.

5. The system according to claim 1, characterized in that, The average COT value for each group of furnace tubes is calculated using the following formula: R t =ΣA i / N,(i=1,2,3…,N), Among them, R t Let A be the average COT of the furnace tubes in group t. i This represents the COT value of the i-th furnace tube in the t-th group of furnace tubes, and N is the number of furnace tubes in the t-th group of furnace tubes. If the COT value of a single furnace tube is bad, it is not included in the count. The average COT of all furnace tubes is calculated using the following formula: R M =ΣR t / M,(t=1,2,3…,M) Among them, R M R is the average COT of all furnace tubes. t Let COT be the average value of the t-th group of furnace tubes, and M be the total number of groups of furnace tubes.

6. A method for controlling the temperature difference in a pyrolysis furnace, wherein the sidewall fuel gas nozzles of the pyrolysis furnace are grouped according to the number of pyrolysis gas outlet groups in the radiant section, and multiple control valves are set corresponding to the number of pyrolysis gas outlet groups in the radiant section of the pyrolysis furnace, each control valve being used to control the flow rate of a group of sidewall fuel gas nozzles to adjust the radiant section outlet temperature (COT) of the corresponding group of furnace tubes, the method comprising: Calculate the difference between the average COT of each group of furnace tubes and the average COT of all furnace tubes; Adjust the opening degree of the corresponding control valve according to the difference in value for each group of furnace tubes.

7. The method according to claim 6, characterized in that, The feed rate of each group of furnace tubes is controlled in cascade by the feed rate controller of the pyrolysis furnace to ensure that the feed rate of each group of furnace tubes is the same.

8. The method according to claim 6, characterized in that, The average COT value of all furnace tubes is transmitted to the bottom fuel gas controller of the cracking furnace to adjust the bottom fuel gas quantity.

9. The method according to claim 6, characterized in that, The opening degree of the corresponding control valve is adjusted according to the higher of the difference between each group of furnace tubes and the preset minimum value.

10. The method according to claim 6, characterized in that, The average COT value for each group of furnace tubes is calculated using the following formula: R t =ΣA i / N,(i=1,2,3…,N), Among them, R t Let A be the average COT of the furnace tubes in group t. i This represents the COT value of the i-th furnace tube in the t-th group of furnace tubes, and N is the number of furnace tubes in the t-th group of furnace tubes. If the COT value of a single furnace tube is bad, it is not included in the count. The average COT of all furnace tubes is calculated using the following formula: R M =ΣR t / M,(t=1,2,3…,M) Among them, R M R is the average COT of all furnace tubes. t Let COT be the average value of the t-th group of furnace tubes, and M be the total number of groups of furnace tubes.

11. A pyrolysis furnace, characterized in that, Includes a pyrolysis furnace temperature difference control system as described in any one of claims 1-5.

12. A machine-readable storage medium storing instructions for causing a machine to perform the pyrolysis furnace temperature difference control method as described in any one of claims 6-10.

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