A cracking furnace

Abstract

The present disclosure relates to a cracking furnace, in which a plurality of mutually-parallel convection section preheating pipes in communication with a plurality of raw material pipes are in communication with a plurality of mutually-parallel radiant furnace pipe groups in the same radiant furnace through at least one cross pipe, and for a single cross pipe, cracking raw materials from different raw material pipes preheated through the convection section preheating pipes can be mixed in a header or manifold before entering the cross pipe and then enter the cross pipe, which can make the cracking raw materials entering each radiant furnace pipe group corresponding to the cross pipe have the same original temperature; meanwhile, each radiant furnace pipe group is correspondingly provided with a secondary fuel branch pipe, and each secondary fuel branch pipe is used to provide fuel to the burner corresponding to each radiant furnace pipe group, so that the fuel flow rate flowing into the burner corresponding to each radiant furnace pipe group can be accurately regulated through each secondary fuel branch pipe.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of petroleum chemical industry, in particular to a cracking furnace. BACKGROUND

[0002] The cracking furnace is a core equipment for producing ethylene, propylene and other products by cracking hydrocarbons under the action of high-temperature steam, and the cracking reaction occurs in the radiant furnace tube of the cracking furnace, and the heat required for cracking is supplied by the burner.

[0003] In the cracking process, the cracking conditions such as "high temperature, short residence time and low hydrocarbon partial pressure" and the radiant furnace tube configuration of the cracking furnace are important factors affecting the cracking selectivity. However, in the actual control of the cracking furnace, since the radiant furnace tube configuration of the cracking furnace has been determined, the residence time of the cracking raw material in the cracking furnace is basically unchanged under the condition that the feeding amount and properties of the cracking raw material are unchanged, and since the ratio of the cracking raw material to the dilution steam is maintained constant, the hydrocarbon partial pressure in the cracking furnace is also basically unchanged, so in the actual operation, the cracking depth of different types of cracking raw materials is mainly controlled by adjusting the average outlet temperature of the radiant furnace tube of the cracking furnace.

[0004] The existing cracking furnace indirectly controls the average outlet temperature of the radiant furnace tube of each large group by regulating the flow rate of the raw material flowing through each raw material pipe and regulating the total flow rate of the fuel flowing through the side wall fuel main pipe and the bottom fuel main pipe. Since the flow rate of the raw material entering each radiant furnace tube group or each radiant furnace tube group is limited, in order to ensure the same cracking depth, it is necessary to ensure that the flow rate of the raw material entering each radiant furnace tube group is the same or within a certain range. Generally, a Venturi is used for flow distribution, and when the flow rate is limited to a certain value, flow deviation will occur. Therefore, when the burner corresponding to each large group of radiant furnace tubes cannot be adjusted, accurate control of the average outlet temperature of the radiant furnace tube cannot be achieved. SUMMARY

[0005] The purpose of the present disclosure is to solve the problem that the existing cracking furnace cannot achieve accurate control of the average outlet temperature of the radiant furnace tube, and to provide a cracking furnace.

[0006] In order to achieve the above-mentioned purpose, the present disclosure provides a cracking furnace, which comprises a raw material pipe, a convection section, a cross pipe, a radiant section, a burner and a fuel pipe, a plurality of preheating pipes are arranged in parallel in the convection section, a plurality of radiant furnace tube groups are arranged in the radiant section, one radiant furnace tube group is composed of at least one radiant furnace tube group, the burner is arranged at least at the bottom, the side wall or the top of the radiant section, and the arrangement position of the burner is such that one radiant furnace tube group corresponds to at least one burner.

[0007] One of the raw material pipes is communicated with at least one of the preheating pipes in the convection section, and a plurality of the preheating pipes arranged in parallel with each other are communicated with a plurality of groups of the radiant furnace pipes arranged in parallel with each other in the same radiant furnace through at least one of the cross pipes, wherein one of the cross pipes corresponds to M of the raw material pipes and N of the groups of the radiant furnace pipes, M and N are positive integers;

[0008] The fuel pipes include primary fuel main pipes and secondary fuel branch pipes, one of the cross pipes corresponds to at least one of the primary fuel main pipes, the primary fuel main pipes are used to provide fuel to all burners corresponding to all groups of the radiant furnace pipes communicated with the cross pipe; one of the groups of the radiant furnace pipes corresponds to one of the secondary fuel branch pipes, the secondary fuel branch pipes are used to provide fuel to the burners corresponding to the group of the radiant furnace pipes; for a single cross pipe, a plurality of the secondary fuel branch pipes corresponding to all groups of the radiant furnace pipes communicated with the single cross pipe are connected in parallel with each other, and then connected in parallel and / or in series with the primary fuel main pipe corresponding to the single cross pipe.

[0009] Optionally, one of the cross pipes corresponds to M of the raw material pipes and N of the groups of the radiant furnace pipes, M and N are positive integers, and 1≤M≤N, N≥1; preferably, 2≤M≤4, 2≤N≤4.

[0010] Optionally, each furnace corresponds to L of the cross pipes, L is an integer greater than or equal to 2 and less than or equal to 4, preferably an even integer greater than or equal to 2 and less than or equal to 4.

[0011] Optionally, for a single cross pipe, among all burners corresponding to the single cross pipe, the burners arranged at the bottom of the radiant section furnace, the burners arranged at the sidewall of the radiant section furnace, and the burners arranged at the top of the radiant section furnace correspond to one of the primary fuel main pipes respectively.

[0012] Optionally, one end of the primary fuel main pipe close to the burners is divided into a first sub-main pipe and a second sub-main pipe, the burners have primary lances and secondary lances, for a single primary fuel main pipe, the first sub-main pipe is used to provide fuel to the primary lances of all burners corresponding to the single primary fuel main pipe, and the second sub-main pipe is used to provide fuel to the secondary lances of all burners corresponding to the single primary fuel main pipe; the first sub-main pipe is communicated with at least one of the secondary fuel branch pipes arranged in parallel with each other, and the second sub-main pipe is communicated with at least one of the secondary fuel branch pipes arranged in parallel with each other.

[0013] Optionally, the burner is provided with a primary lance and a secondary lance, and the secondary fuel branch is divided into a first sub-branch and a second sub-branch near one end of the burner, the first sub-branch is communicated with the primary lance of the corresponding plurality of burners corresponding to the radiant tube group, and the second sub-branch is communicated with the secondary lance of the corresponding plurality of burners corresponding to the radiant tube group.

[0014] Optionally, the primary fuel main pipe is provided with a primary regulating valve, and the secondary fuel branch is provided with a secondary regulating valve.

[0015] Optionally, the primary fuel main pipe is provided with a primary regulating valve, and the first sub-branch of the secondary fuel branch is provided with a secondary regulating valve.

[0016] Optionally, the primary fuel main pipe is provided with a primary regulating valve, and the second sub-branch of the secondary fuel branch is provided with a secondary regulating valve.

[0017] Optionally, the primary fuel main pipe is further provided with a total heat value controller, the total heat value controller is used for monitoring the actual total heat release after the fuel flowing through the primary fuel main pipe is burned, and when the absolute value of the difference between the actual total heat release and the theoretical total heat is greater than a first preset value, the primary regulating valve is prompted to be adjusted, wherein the theoretical total heat refers to the total heat required to make the total average temperature of the radiant tube group corresponding to the transverse tube corresponding to the primary fuel main pipe reach a first preset temperature.

[0018] Optionally, the secondary fuel branch is further provided with a sub-heat value controller, the sub-heat value controller is used for monitoring the actual sub-heat release after the fuel flowing through the secondary fuel branch is burned, and when the absolute value of the difference between the actual sub-heat release and the theoretical sub-heat is greater than a second preset value, the secondary regulating valve is prompted to be adjusted, wherein the theoretical sub-heat refers to the sub-heat required to make the average temperature of the radiant tube group corresponding to the secondary fuel branch reach a second preset temperature.

[0019] Optionally, one of the radiant tube groups is provided with one secondary temperature controller, the secondary temperature controller is used for monitoring the actual radiant tube outlet average temperature of the radiant tube group, and when the absolute value of the difference between the actual radiant tube outlet average temperature and the second preset temperature is greater than a third preset value, the secondary regulating valve on the secondary fuel branch corresponding to the radiant tube group is prompted to be adjusted.

[0020] Optionally, a primary temperature controller is provided for each of the transverse tubes. The primary temperature controller is used to monitor the actual total average temperature of the furnace tube outlet of all radiant furnace tube groups corresponding to the transverse tube, and when the absolute value of the difference between the actual total average temperature of the furnace tube outlet and the first preset temperature is greater than a fourth preset value, it prompts the adjustment of the primary regulating valve on the primary fuel main pipe corresponding to the transverse tube.

[0021] Optionally, the raw material pipeline is equipped with a raw material flow regulating valve;

[0022] The primary temperature controller is also used to prompt adjustment of the raw material flow regulating valve on the raw material pipeline corresponding to the cross tube when the absolute value of the difference between the actual total average temperature at the furnace tube outlet and the first preset temperature is greater than a fourth preset value. In principle, this ensures that it serves as a supplementary adjustment method in special circumstances, such as strictly controlling the raw material flow rate adjustment within a minimum variation range when pyrolyzing the same raw material, for example, less than 5% between the maximum and minimum values.

[0023] Optionally, the pyrolysis furnace further includes a cooling medium pipeline, which is connected to the raw material pipeline and / or the cross pipe, for injecting cooling medium into the raw material pipeline and / or the cross pipe.

[0024] Through the above technical solution, the pyrolysis furnace provided in this disclosure has multiple parallel convection preheating pipes connected to multiple parallel raw material pipes, which are connected to multiple parallel radiant furnace tube groups via at least one cross pipe. For a single cross pipe, the pyrolysis raw materials from different raw material pipes, after being preheated by the preheating pipes, can be mixed in a header or manifold before entering the corresponding radiant furnace tube group. This ensures that the pyrolysis raw materials entering each radiant furnace tube group corresponding to the cross pipe have the same initial temperature and pressure. Simultaneously, each radiant furnace tube group is equipped with a corresponding secondary fuel branch pipe, which is used to supply fuel to the burners corresponding to each radiant furnace tube group. Therefore, the fuel flow rate into the burners corresponding to each radiant furnace tube group can be precisely controlled through the secondary fuel branch pipes. Thus, the pyrolysis furnace of this disclosure can effectively improve the accuracy of controlling the average outlet temperature of each radiant furnace tube group. Ultimately, the goal is to ensure that the pyrolysis feedstock and dilution steam mixture entering the radiation section have the same or minimally different inlet and outlet conditions and residence time, so as to achieve the same pyrolysis efficiency and operating cycle, and well meet the objective of "high temperature, short residence time and low hydrocarbon partial pressure".

[0025] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0027] Figure 1 A schematic diagram of the structure of a pyrolysis furnace according to an embodiment of the present disclosure is shown.

[0028] Figure 2 A schematic diagram of the structure of another pyrolysis furnace according to an embodiment of the present disclosure is shown;

[0029] Figure 3 A schematic diagram of the structure of another pyrolysis furnace according to an embodiment of the present disclosure is shown.

[0030] Figure 4 A schematic diagram of the structure of another pyrolysis furnace according to an embodiment of the present disclosure is shown.

[0031] Explanation of reference numerals in the attached figures

[0032] 1. Raw material pipeline 2. Convection section

[0033] 3. Transverse tube 4 Radiation section

[0034] 5. Burner 6. Fuel Pipeline

[0035] 7. Radiation furnace tube assembly; 8. Primary fuel main pipe.

[0036] 9 Secondary fuel branch pipe 10 Primary regulating valve

[0037] 11 Secondary regulating valve 12 First sub-branch pipe

[0038] 13 Second branch pipe 14 Cooling medium pipeline Detailed Implementation

[0039] The specific embodiments of this disclosure 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 this disclosure.

[0040] The existing pyrolysis furnace includes feedstock pipes, a convection section, a cross tube, a radiant section, burners, and fuel pipes. Multiple radiant furnace tube groups are arranged within the radiant section. Each feedstock pipe, after passing through the convection section, connects to one radiant furnace tube group via a cross tube. The other end of each feedstock pipe connects to a feedstock main pipe. Mass flow meters are installed on the feedstock main pipe or each feedstock pipe to control the flow rate of pyrolysis feedstock entering each radiant furnace tube group. Burners are located on the side walls and bottom of the radiant section to provide heat to each radiant furnace tube group. The fuel pipes include a side wall fuel main pipe and a bottom fuel main pipe. The side wall fuel main pipe supplies fuel to the side wall burners, and the bottom fuel main pipe supplies fuel to the bottom burners. Side wall regulating valves and bottom regulating valves are installed on the side wall fuel main pipe and bottom fuel main pipe, respectively, to regulate the total fuel flow rate supplied to the side wall burners and bottom fuel main pipe, respectively.

[0041] The inventors of this disclosure have discovered that existing pyrolysis furnaces indirectly control the average outlet temperature of each radiant furnace tube group by regulating the flow rate of raw materials flowing through each raw material pipeline and the total combustion flow rate flowing through the sidewall fuel main and bottom fuel main. This configuration has at least the following problems:

[0042] (1) By regulating the total flow of fuel supplied to the side wall burners and bottom burners, it is only possible to regulate the total average temperature of the furnace tube outlet of all radiant furnace tube groups, but not to regulate the average temperature of the furnace tube outlet of each radiant furnace tube group. Since the combustion conditions of the burners corresponding to each radiant furnace tube group may be different, the average temperature of the furnace tube outlet of each radiant furnace tube group may vary greatly.

[0043] (2) The difference in the average outlet temperature of the furnace tubes of each group of radiant furnace tubes needs to be eliminated by adjusting the raw material flow rate in the corresponding raw material pipeline. This will result in differences in the raw material flow rate, inlet pressure, inlet temperature and residence time of each group of radiant furnace tubes, which in turn leads to different cracking depths of the cracking raw materials between different groups, further causing coking of the radiant furnace tubes, shortening the operating cycle of the cracking furnace radiant furnace tubes, increasing the number of coking times, and affecting the production efficiency of the unit. Moreover, the adjustment of the raw material flow rate is limited by the distribution flow deviation in the venturi of the radiant section furnace tube inlet, that is, the adjustment range of the raw material flow rate is limited. Therefore, it is impossible to ensure that the raw materials in each group of radiant furnace tubes have the same or similar cracking depth.

[0044] (3) There are a large number of cross tubes. Usually, a raw material pipeline is connected to a radiant furnace tube group through a cross tube. When the raw material in each raw material pipeline flows through the convection section, the heat absorbed by the raw material in each raw material pipeline during the preheating process may be different due to the influence of the flue gas flow deviation and the raw material flow rate difference in the convection section. This will lead to a deviation in the initial temperature of the raw material entering each radiant furnace tube group through each cross tube, resulting in a large difference in the average temperature of the furnace tube outlet of each radiant furnace tube group.

[0045] (4) When a pyrolysis furnace is used to pyrolyze multiple pyrolysis feedstocks at the same time, different radiant furnace tube groups need to pyrolyze different pyrolysis feedstocks. Since the pyrolysis performance of different pyrolysis feedstocks varies greatly, it is necessary to set different furnace tube outlet average temperatures for radiant furnace tube groups that pyrolyze different pyrolysis feedstocks so that different pyrolysis feedstocks have appropriate pyrolysis depths. However, existing pyrolysis furnaces find it difficult to meet this requirement.

[0046] (5) In practical applications, in order to improve the online rate of the cracking furnace, it is often necessary to crack some of the radiant furnace tube groups for cracking raw materials and clean some of the radiant furnace tube groups for coking. This requires setting different average furnace tube outlet temperatures for the cracking side radiant furnace tube groups and the coking side radiant furnace tube groups. Existing cracking furnaces are difficult to achieve this requirement.

[0047] (6) Due to the different raw material flow rates in the existing technology, the worst case will cause the Venturi to deviate. In addition, the different temperatures entering the radiation section will cause different coking, resulting in different pressure drops in the radiation furnace tube.

[0048] Due to the aforementioned problems, the goal of "high temperature, short residence time and low hydrocarbon partial pressure" cannot be well achieved, resulting in a decrease in cracking efficiency (olefin yield and selectivity) and a shortening of the cracking furnace operating cycle.

[0049] To address the aforementioned problems, this disclosure provides a pyrolysis furnace. The pyrolysis furnace may include a raw material pipeline 1, a convection section 2, a transverse pipe 3, a radiant section 4, a burner 5, and a fuel pipeline 6. The convection section 2 contains multiple parallel preheating pipes. The radiant section 4 contains multiple radiant furnace tube groups 7, each radiant furnace tube group 7 consisting of at least one radiant furnace tube subgroup. The burner 5 is located at least one location on the bottom, side wall, or top of the radiant section 4, and the burner 5 is positioned such that each radiant furnace tube group 7 corresponds to at least one burner 5.

[0050] One of the raw material pipes 1 is connected to at least one of the preheating pipes in the convection section 2. Multiple preheating pipes arranged in parallel are connected to multiple groups of radiant furnace tubes 7 arranged in parallel within the same radiant furnace chamber through at least one cross pipe 3. M of the raw material pipes 1 and N groups of radiant furnace tubes 7 are provided for one cross pipe 3, where M and N are positive integers.

[0051] The fuel pipeline 6 includes a primary fuel main pipe 8 and secondary fuel branch pipes 9. At least one primary fuel main pipe 8 is provided for each of the cross pipes 3. The primary fuel main pipe 8 is used to supply fuel to all burners 5 corresponding to all radiant furnace tube groups 7 connected to the cross pipe 3. One secondary fuel branch pipe 9 is provided for each radiant furnace tube group 7. The secondary fuel branch pipe 9 is used to supply fuel to the burner 5 corresponding to the radiant furnace tube group 7. For a single cross pipe 3, multiple secondary fuel branch pipes 9 corresponding to all radiant furnace tube groups 7 connected to the single cross pipe 3 are connected in parallel to each other and then connected in parallel and / or in series with the primary fuel main pipe 8 corresponding to the single cross pipe 3.

[0052] In this disclosure, specifically, multiple parallel feedstock pipes are connected to multiple parallel preheating pipes in the convection section. These parallel preheating pipes are then connected to multiple parallel radiant furnace tube groups via a cross-pipe. For a single cross-pipe, the pyrolysis feedstock from the multiple feedstock pipes, after being preheated in the convection section preheating pipe, is mixed in a header or manifold before entering each radiant furnace tube group. For a single cross-pipe, fuel from the boundary area first enters the corresponding primary fuel main pipe, then is diverted according to actual needs into secondary fuel branch pipes corresponding to each radiant furnace tube group, and finally diverted from each secondary fuel branch pipe into each burner corresponding to each radiant furnace tube group.

[0053] The pyrolysis furnace disclosed herein can achieve at least the following effects:

[0054] (1) It can adjust the total average temperature of the furnace tube outlet of multiple radiant furnace tube groups corresponding to the cross tubes of the primary fuel main pipe by adjusting the fuel flow rate through the primary fuel main pipe.

[0055] (2) By adjusting the fuel flow rate through each secondary fuel branch pipe, the deviation of the average outlet temperature of each radiant furnace tube group can be brought close to zero. This is not only conducive to the long-term stable operation of the cracking furnace and the service life of the radiant furnace tubes, but also conducive to improving the stability of product quality.

[0056] (3) The number of cross tubes has been reduced. The pyrolysis feedstock from multiple feedstock pipelines can be mixed before entering each radiant furnace tube group. This enables the pyrolysis feedstock entering each radiant furnace tube group to have the same original temperature, pressure and flow rate, thereby further reducing the deviation between the average outlet temperatures of the furnace tubes of each radiant furnace tube group.

[0057] (4) When different radiant furnace tube groups are used to crack different cracking feedstocks, by adjusting the fuel flow through the primary fuel branch pipe and each secondary fuel branch pipe, the radiant furnace tube groups cracking different cracking feedstocks can have different average furnace tube outlet temperatures. This can ensure that different cracking feedstocks maintain a suitable cracking depth during cracking, thereby overcoming the impact of different types of cracking feedstocks grouped cracking on the cracking furnace, maximizing the profit of the target cracking product and ensuring the stable operation of the cracking furnace.

[0058] (5) When cracking the raw material of a radiant furnace tube group corresponding to a cross tube and cleaning the coke of another radiant furnace tube group, by adjusting the flow rate of fuel flowing through the regulating valve of the primary fuel main pipe and each secondary fuel branch pipe, the radiant furnace tube group on the cracking side and the radiant furnace tube group on the cleaning side can have different average furnace tube outlet temperatures. Thus, without affecting the overall operation of the cracking furnace, the cleaning of some radiant furnace tube groups can be achieved separately. This can significantly improve the online rate of the cracking furnace and maximize the benefits of the cracking furnace.

[0059] (6) A small range of adjustment is made to the raw material corresponding to a cross tube, while the adjustment ensures that the average temperature deviation of the large group of radiant furnace tubes corresponding to different cross tubes is ensured when cracking the same raw material. This can better adapt to the working conditions of cracking different raw materials or coking in the radiant section furnace tubes corresponding to different cross tubes, meet the above conditions, and make the operation more flexible.

[0060] According to this disclosure, in the pyrolysis furnace, one of the transverse pipes 3 can be correspondingly provided with M of the raw material pipes 1 and N of the radiant furnace tube groups 7, where M and N are positive integers, and 1≤M≤N, N≥1; preferably, 2≤M≤4, 2≤N≤4.

[0061] According to this disclosure, each furnace chamber is provided with L transverse tubes 3, where L is an integer greater than or equal to 2 and less than or equal to 4, preferably an even number greater than or equal to 2 and less than or equal to 4.

[0062] According to this disclosure, for a single cross tube, among all the burners corresponding to the single cross tube, the burner located at the bottom of the radiant section furnace, the burner located on the side wall of the radiant section furnace, and the burner located at the top of the radiant section furnace can each be respectively provided with one primary fuel main pipe.

[0063] In this disclosure, at least the following regulation methods can be achieved through the primary fuel main pipe: regulating the fuel gas of the burner at the bottom of the radiant section furnace individually; regulating the fuel gas of the burner on the side wall of the radiant section furnace individually; regulating the fuel gas of the burner at the top of the radiant section furnace individually; regulating the fuel gas of any two burners at the bottom, side wall, and top of the radiant section furnace; and regulating the fuel gas of the burners at the bottom, side wall, and top of the radiant section furnace simultaneously.

[0064] According to this disclosure, the end of the primary fuel main pipe near the burner can be divided into a first sub-main pipe and a second sub-main pipe. The burner has a primary spray gun and a secondary spray gun. For a single primary fuel main pipe, the first sub-main pipe is used to supply fuel to the primary spray guns of all burners corresponding to the single primary fuel main pipe, and the second sub-main pipe is used to supply fuel to the secondary spray guns of all burners corresponding to the single primary fuel main pipe. The first sub-main pipe is connected to at least one parallel secondary fuel branch pipe, and the second sub-main pipe is connected to at least one parallel secondary fuel branch pipe.

[0065] According to this disclosure, the burner 5 may be provided with a primary spray gun and a secondary spray gun. The end of the secondary fuel branch pipe 9 near the burner 5 may be divided into a first sub-branch pipe 12 and a second sub-branch pipe 13. The first sub-branch pipe 12 is connected to the primary spray guns of a plurality of burners 5 corresponding to the radiant furnace tube group 7, and the second sub-branch pipe 13 is connected to the secondary spray guns of a plurality of burners 5 corresponding to the radiant furnace tube group 7.

[0066] According to this disclosure, in order to more conveniently control the fuel flow through the primary fuel main pipe and the secondary fuel branch pipe, preferably, the primary fuel main pipe 8 is provided with a primary regulating valve 10 and the secondary fuel branch pipe 9 is provided with a secondary regulating valve 11; or, the primary fuel main pipe 8 is provided with a primary regulating valve 10 and the first sub-branch pipe 12 of the secondary fuel branch pipe 9 is provided with a secondary regulating valve 11; or, the primary fuel main pipe 8 is provided with a primary regulating valve 10 and the second sub-branch pipe 13 of the secondary fuel branch pipe 9 is provided with a secondary regulating valve 11.

[0067] In this disclosure, the following three adjustment methods are achieved by adjusting the secondary regulating valve: adjusting the fuel gas corresponding to a single group of radiant furnace tubes; adjusting the fuel gas corresponding to the primary fuel gun of a single group of radiant furnace tubes; and adjusting the fuel gas corresponding to the secondary fuel gun of a single group of radiant furnace tubes.

[0068] According to this disclosure, the primary fuel main pipe 8 may also be equipped with a total calorific value controller. The total calorific value controller is used to monitor the actual total heat release after the fuel flowing through the primary fuel main pipe 8 is burned, and when the absolute value of the difference between the actual total heat release and the theoretical total heat is greater than a first preset value, it prompts the adjustment of the primary regulating valve 10. The theoretical total heat refers to the total heat required to make the total average temperature of the furnace tube outlet of each group of radiant furnace tubes 7 connected to the transverse pipe 3 corresponding to the primary fuel main pipe 8 reach the first preset temperature.

[0069] In this disclosure, specifically, the primary fuel main pipe is used to provide the fuel required for the cracking of the pyrolysis feedstock to all radiant furnace tube groups corresponding to a single transverse tube. After these fuels enter the burner and are burned, the heat provided can make the total average temperature of the furnace tube outlet of all radiant furnace tube groups corresponding to a single transverse tube reach a first preset temperature.

[0070] The total average temperature at the furnace tube outlet refers to the arithmetic mean of the average temperatures at the furnace tube outlets of each radiant furnace tube group. The first preset temperature can be set according to the type of pyrolysis feedstock in each radiant furnace tube group. The purpose of setting this temperature is to ensure that the pyrolysis feedstock in all radiant furnace tube groups has a suitable pyrolysis depth.

[0071] According to this disclosure, the secondary fuel branch pipe 9 may also be equipped with a sub-calorific value controller. The sub-calorific value controller is used to monitor the actual sub-calorific value released after the fuel flows through the secondary fuel branch pipe 9 is burned, and when the absolute value of the difference between the actual sub-calorific value and the theoretical sub-calorific value is greater than a second preset value, it prompts the adjustment of the secondary regulating valve 11. The theoretical sub-calorific value refers to the sub-calorific value required to make the average temperature of the furnace tube outlet of the radiant furnace tube group 7 corresponding to the secondary fuel branch pipe 9 reach the second preset temperature.

[0072] In this disclosure, specifically, the secondary fuel branch pipe is used to provide the fuel required for the cracking of the cracking feedstock to a single radiant furnace tube group. After the fuel enters the burner and is burned, the heat provided can make the average temperature of the furnace tube outlet of the single radiant furnace tube group reach a second preset temperature.

[0073] The average outlet temperature of the furnace tubes refers to the arithmetic mean of the average outlet temperatures of the various subgroups of radiant furnace tubes that make up the large radiant furnace tube group. The second preset temperature can be set according to the type of pyrolysis feedstock in the large radiant furnace tube group. The purpose of setting this temperature is to ensure that the pyrolysis feedstock in the large radiant furnace tube group has an appropriate pyrolysis depth. Optionally, the second preset temperature is the same for large radiant furnace tube groups pyrolyzing the same type of pyrolysis feedstock, while the second preset temperature can be different for large radiant furnace tube groups pyrolyzing different pyrolysis feedstocks.

[0074] Furthermore, for a single transverse tube, the arithmetic mean of the second preset temperatures corresponding to all the large groups of radiant furnace tubes corresponding to that single transverse tube is the first preset temperature corresponding to that single transverse tube.

[0075] According to this disclosure, a secondary temperature controller can be correspondingly set for each of the radiant furnace tube groups. The secondary temperature controller is used to monitor the actual average temperature of the furnace tube outlet of the radiant furnace tube group, and when the absolute value of the difference between the actual average temperature of the furnace tube outlet and the second preset temperature is greater than a third preset value, it prompts to adjust the secondary regulating valve on the secondary fuel branch pipe corresponding to the radiant furnace tube group.

[0076] According to this disclosure, a primary temperature controller can be correspondingly set for each of the transverse tubes. The primary temperature controller is used to monitor the actual total average temperature of the furnace tube outlet of all radiant furnace tube groups corresponding to the transverse tube, and when the absolute value of the difference between the actual total average temperature of the furnace tube outlet and the first preset temperature is greater than the fourth preset value, it prompts to adjust the primary regulating valve on the primary fuel main pipe corresponding to the transverse tube.

[0077] According to this disclosure, the raw material pipeline is equipped with a raw material flow regulating valve; the primary temperature controller can also be used to prompt the adjustment of the raw material flow regulating valve on the raw material pipeline corresponding to the cross pipe when the absolute value of the difference between the actual furnace tube outlet total average temperature and the first preset temperature is greater than a fourth preset value.

[0078] According to this disclosure, the pyrolysis furnace further includes a cooling medium pipeline 14, which is connected to the raw material pipeline 1 and / or the cross pipe 3, and is used to inject a cooling medium into the raw material pipeline 1 and / or the cross pipe 3.

[0079] In this disclosure, specifically, the cooling medium can be cooling water, which can be boiler feedwater or demineralized water, etc. The cooling medium pipeline can be located at any position between the inlet, outlet, or intermediate position of the upper mixing heat exchange module, preferably between the outlet of the upper mixing superheater module in the convection section and the lower mixing superheater module. The cooling medium pipeline is used to inject cooling medium into the feed pipeline and / or cross-pipe when the temperature of the raw material entering each radiant furnace tube group is too high, or when different radiant furnace tube groups are under different operating conditions. For example, when some radiant furnace tube groups are used for pyrolysis, while others are undergoing coking or hot standby, cooling medium can be injected into the coking or hot standby radiant furnace tube groups through the cooling medium pipeline.

[0080] Figure 1 A schematic diagram of the structure of a pyrolysis furnace according to an embodiment of the present disclosure is shown, such as... Figure 1As shown, in this cracking furnace, each furnace chamber in the radiant section 4 is equipped with 6 radiant furnace tube groups 7, and each furnace chamber is equipped with 2 cross pipes 3 (only one is shown in the figure). Each cross pipe 3 corresponds to 3 radiant furnace tube groups 7, 1 primary fuel main pipe 8, and 3 secondary fuel branch pipes 9. Among them, the 3 secondary fuel branch pipes 9 branch into 3 first sub-branch pipes 12 and 3 second sub-branch pipes 13. The first sub-branch pipes 12 go to the primary spray gun of the bottom burner 5, and the second sub-branch pipes 13 go to the secondary spray gun of the bottom burner 5.

[0081] The fuel gas flow rate is finely adjusted by the secondary regulating valve 11 installed on the second sub-branch pipe 13 leading to the secondary spray gun to reduce the deviation of the average outlet temperature (COT-A) of a single radiant furnace tube group 7 when cracking the same feedstock. At the same time, the total fuel flow rate is adjusted by the primary regulating valve 10 installed on the primary fuel main pipe 8, thereby achieving the adjustment of the average outlet temperature (COT-G) of the multiple radiant furnace tube groups 7 corresponding to each cross pipe 3.

[0082] Figure 2 A schematic diagram of the structure of another pyrolysis furnace according to an embodiment of the present disclosure is shown, such as... Figure 2 As shown, in this cracking furnace, each furnace chamber in the radiant section 4 is equipped with 6 radiant furnace tube groups 7, and each furnace chamber is equipped with 3 cross pipes 3 (only one is shown in the figure). Each cross pipe 3 corresponds to 2 radiant furnace tube groups 7, 1 primary fuel main pipe 8, and 2 secondary fuel branch pipes 9. Among them, the 2 secondary fuel branch pipes 9 branch into 2 first sub-branch pipes 12 and 2 second sub-branch pipes 13. The first sub-branch pipes 12 go to the primary spray gun of the bottom burner 5, and the second sub-branch pipes 13 go to the secondary spray gun of the bottom burner 5.

[0083] The fuel gas flow rate is finely adjusted by the secondary regulating valve 11 installed on the second sub-branch pipe 13 leading to the secondary spray gun to reduce the deviation of the average outlet temperature (COT-A) of a single radiant furnace tube group 7 when cracking the same feedstock. At the same time, the total fuel flow rate is adjusted by the primary regulating valve 10 installed on the primary fuel main pipe 8, thereby achieving the adjustment of the average outlet temperature (COT-G) of the multiple radiant furnace tube groups 7 corresponding to each cross pipe 3.

[0084] Figure 3 A schematic diagram of the structure of another pyrolysis furnace according to an embodiment of the present disclosure is shown, such as... Figure 3 As shown, in this pyrolysis furnace, each furnace chamber in the radiant section 4 is equipped with 6 radiant furnace tube groups 7, and each furnace chamber is equipped with 2 cross tubes 3 (only one is shown in the figure). Each cross tube 3 corresponds to 3 radiant furnace tube groups 7, 1 primary fuel main pipe 8 and 3 secondary fuel branch pipes 9. The secondary fuel branch pipes 9 go to the bottom burner 5.

[0085] The fuel gas flow rate is finely adjusted by the secondary regulating valve 11 installed on the secondary fuel branch pipe 9 to reduce the deviation of the average outlet temperature (COT-A) of a single radiant furnace tube group 7 when cracking the same feedstock. At the same time, the total fuel flow rate is adjusted by the primary regulating valve 10 installed on the primary fuel main pipe 8, thereby achieving the adjustment of the average outlet temperature (COT-G) of multiple radiant furnace tube groups 7 corresponding to each cross pipe 3.

[0086] Figure 4 A schematic diagram of the structure of another pyrolysis furnace according to an embodiment of the present disclosure is shown, such as... Figure 4 As shown, in this cracking furnace, each furnace chamber in the radiant section 4 is equipped with 6 radiant furnace tube groups 7, and each furnace chamber is equipped with 2 cross tubes 3 (only one is shown in the figure). Each cross tube 3 corresponds to 3 radiant furnace tube groups 7 and 1 primary fuel main pipe 8. The primary fuel main pipe 8 is divided into two primary fuel branch pipes. One primary fuel branch pipe goes to the bottom combustion system, and the other primary fuel branch pipe goes to the side wall combustion system. The primary fuel branch pipe going to the bottom combustion system is divided into 3 secondary fuel branch pipes 9 and goes to the bottom burner 5. The primary fuel branch pipe going to the side wall combustion system is divided into 3 secondary fuel branch pipes 9 and goes to the side wall burner 5.

[0087] The fuel gas flow rate is finely adjusted by the secondary regulating valves 11 installed on the secondary fuel branch pipes 9 at the bottom and side walls to reduce the deviation of the average outlet temperature (COT-A) of a single radiant furnace tube group 7 when cracking the same feedstock. At the same time, the total fuel flow rate is adjusted by the primary regulating valve 10 installed on the primary fuel main pipe 8, thereby achieving the adjustment of the average outlet temperature (COT-G) of the multiple radiant furnace tube groups 7 corresponding to each cross pipe 3.

[0088] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0089] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0090] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A pyrolysis furnace, characterized in that, The pyrolysis furnace includes a raw material pipeline, a convection section, a cross tube, a radiant section, a burner, and a fuel pipeline. The convection section is provided with multiple preheating pipelines arranged in parallel. The radiant section is provided with multiple radiant furnace tube groups, and each radiant furnace tube group consists of at least one radiant furnace tube subgroup. The burner is located at least one location in the bottom, side wall, or top of the radiant section, and the burner is positioned such that each radiant furnace tube group corresponds to at least one burner. One of the raw material pipes is connected to at least one of the preheating pipes in the convection section, and multiple parallel preheating pipes are connected to multiple parallel groups of radiant furnace tubes in the same radiant furnace chamber through at least one cross pipe. Each cross pipe corresponds to M raw material pipes and N groups of radiant furnace tubes, where M and N are positive integers and 2≤M≤4, 2≤N≤4. The fuel pipeline includes a primary fuel main pipe and secondary fuel branch pipes. At least one primary fuel main pipe is provided for each cross pipe, and the primary fuel main pipe is used to supply fuel to all burners corresponding to all radiant furnace tube groups connected to the cross pipe. One secondary fuel branch pipe is provided for each radiant furnace tube group, and the secondary fuel branch pipe is used to supply fuel to the burners corresponding to the radiant furnace tube group. For a single cross pipe, multiple secondary fuel branch pipes corresponding to all radiant furnace tube groups connected to the single cross pipe are connected in parallel to each other, and then connected in parallel and / or in series with the primary fuel main pipe corresponding to the single cross pipe. The burner is equipped with a primary spray gun and a secondary spray gun. The secondary fuel branch pipe is divided into a first sub-branch pipe and a second sub-branch pipe at one end near the burner. The first sub-branch pipe is connected to the primary spray gun of multiple burners corresponding to the large group of radiant furnace tubes, and the second sub-branch pipe is connected to the secondary spray gun of multiple burners corresponding to the large group of radiant furnace tubes. Wherein, the primary fuel main pipe is equipped with a primary regulating valve, and the secondary fuel branch pipe is equipped with a secondary regulating valve; and / or, The primary fuel main pipe is equipped with a primary regulating valve, and the first sub-branch of the secondary fuel branch pipe is equipped with a secondary regulating valve; and / or, The primary fuel main pipe is equipped with a primary regulating valve, and the second sub-branch of the secondary fuel branch pipe is equipped with a secondary regulating valve. The primary fuel main pipe is also equipped with a total calorific value controller. The total calorific value controller is used to monitor the actual total heat release after the fuel flows through the primary fuel main pipe is burned. When the absolute value of the difference between the actual total heat release and the theoretical total heat is greater than a first preset value, it prompts the adjustment of the primary regulating valve. The theoretical total heat refers to the total heat required to make the total average temperature of the furnace tube outlet of each group of radiant furnace tubes connected to the transverse pipe corresponding to the primary fuel main pipe reach the first preset temperature. The secondary fuel branch pipe is also equipped with a sub-calorific value controller. The sub-calorific value controller is used to monitor the actual sub-calorific value released after the fuel flows through the secondary fuel branch pipe is burned, and when the absolute value of the difference between the actual sub-calorific value and the theoretical sub-calorific value is greater than a second preset value, it prompts the adjustment of the secondary regulating valve. The theoretical sub-calorific value refers to the sub-calorific value required to make the average temperature of the furnace tube outlet of the radiant furnace tube group corresponding to the secondary fuel branch pipe reach the second preset temperature. A secondary temperature controller is provided for each of the radiant furnace tube groups. The secondary temperature controller is used to monitor the actual average temperature of the furnace tube outlet of the radiant furnace tube group, and when the absolute value of the difference between the actual average temperature of the furnace tube outlet and the second preset temperature is greater than the third preset value, it prompts to adjust the secondary regulating valve on the secondary fuel branch pipe corresponding to the radiant furnace tube group. Each of the transverse tubes is equipped with a primary temperature controller. The primary temperature controller is used to monitor the actual total average temperature of the furnace tube outlet of all radiant furnace tube groups corresponding to the transverse tube. When the absolute value of the difference between the actual total average temperature of the furnace tube outlet and the first preset temperature is greater than the fourth preset value, it prompts the adjustment of the primary regulating valve on the primary fuel main pipe corresponding to the transverse tube.

2. The pyrolysis furnace according to claim 1, characterized in that, Each furnace chamber is equipped with L transverse pipes, where L is an integer greater than or equal to 2 and less than or equal to 4.

3. The pyrolysis furnace according to claim 2, characterized in that, L is an even number greater than or equal to 2 and less than or equal to 4.

4. The pyrolysis furnace according to claim 1, characterized in that, For a single cross tube, among all the burners corresponding to the single cross tube, the burner located at the bottom of the radiant section furnace, the burner located on the side wall of the radiant section furnace, and the burner located at the top of the radiant section furnace are each respectively provided with one primary fuel main pipe.

5. The pyrolysis furnace according to claim 1, characterized in that, The primary fuel main pipe is divided into a first sub-main pipe and a second sub-main pipe at the end near the burner. For a single primary fuel main pipe, the first sub-main pipe is used to supply fuel to the primary nozzles of all burners corresponding to the single primary fuel main pipe, and the second sub-main pipe is used to supply fuel to the secondary nozzles of all burners corresponding to the single primary fuel main pipe. The first sub-main pipe is connected to at least one parallel secondary fuel branch pipe, and the second sub-main pipe is connected to at least one parallel secondary fuel branch pipe.

6. The pyrolysis furnace according to claim 1, characterized in that, The raw material pipeline is equipped with a raw material flow regulating valve; The primary temperature controller is also used to prompt the adjustment of the raw material flow regulating valve on the raw material pipeline corresponding to the cross tube when the absolute value of the difference between the actual total average temperature at the furnace tube outlet and the first preset temperature is greater than the fourth preset value.

7. The pyrolysis furnace according to claim 1, characterized in that, The pyrolysis furnace also includes a cooling medium pipeline, which is connected to the raw material pipeline and / or the cross pipe, and is used to inject cooling medium into the raw material pipeline and / or the cross pipe.

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