CN115873620A - Cracking furnace - Google Patents

Abstract

The present disclosure relates to a cracking furnace, in which a plurality of mutually parallel convection section preheating pipelines communicated with a plurality of raw material pipelines are correspondingly communicated with a plurality of mutually parallel radiation furnace tube large groups in the same radiation furnace chamber through at least one cross pipe, for a single cross pipe, cracking raw materials from different raw material pipelines are preheated by the convection section preheating pipelines and then can enter the cross pipe after being mixed in a header or a manifold before entering the corresponding radiation furnace tube large group, so that the cracking raw materials entering each radiation furnace tube large group corresponding to the cross pipe have the same original temperature; meanwhile, each radiation furnace tube large group is correspondingly provided with a secondary fuel branch pipe, and each secondary fuel branch pipe is respectively used for supplying fuel to the burner corresponding to each radiation furnace tube large group, so that the fuel flow flowing into the burner corresponding to each radiation furnace tube large group can be accurately regulated and controlled through each secondary fuel branch pipe.

Description

Cracking furnace

Technical Field

The disclosure relates to the technical field of petrochemical industry, in particular to a cracking furnace.

Background

The cracking furnace is a core device for producing products such as ethylene, propylene and the like by cracking hydrocarbons under the action of high-temperature steam, cracking reaction occurs in a radiation furnace tube of the cracking furnace, and heat required by cracking is supplied by a combustor.

In the cracking process, the cracking conditions such as high temperature, short residence time and low hydrocarbon partial pressure and the configuration of the radiation furnace tube of the cracking furnace are important factors influencing the cracking selectivity. However, in the actual control of the cracking furnace, because the configuration of the radiation furnace tubes of the cracking furnace is determined, under the condition that the feeding amount and the properties of the cracking raw materials are not changed, the residence time of the cracking raw materials in the cracking furnace is basically unchanged, meanwhile, because the ratio of the cracking raw materials to the dilution steam is kept constant, the hydrocarbon partial pressure in the cracking furnace is also basically unchanged, and therefore, the cracking depths of different types of cracking raw materials are mainly controlled by adjusting the average temperature of the furnace tube outlets of the cracking furnace in the actual operation.

The average temperature of furnace tube outlets of large groups of radiation furnace tubes is indirectly regulated by regulating the flow of raw materials flowing through each raw material pipeline and regulating the total flow of combustion flowing through a side wall fuel main pipe and a bottom fuel main pipe of the existing cracking furnace.

Disclosure of Invention

The utility model aims to solve the problem that the existing cracking furnace can not accurately control the average temperature of the outlet of the furnace tube, and provides a cracking furnace.

In order to achieve the above object, the present disclosure provides a cracking furnace, which includes a raw material pipeline, a convection section, a cross pipe, a radiation section, a burner and a fuel pipeline, wherein a plurality of mutually parallel preheating pipelines are arranged in the convection section, a plurality of radiation furnace tube large groups are arranged in the radiation section, one radiation furnace tube large group is composed of at least one radiation furnace tube small group, the burner is arranged at least one of the bottom, the side wall or the top of the radiation section, and the burner is arranged at a position such that one radiation furnace tube large group corresponds to at least one burner;

the raw material pipeline is communicated with at least one preheating pipeline in the convection section, a plurality of mutually parallel preheating pipelines are communicated with a plurality of mutually parallel radiation furnace tube large groups in the same radiation furnace hearth through at least one cross pipe, wherein M raw material pipelines and N radiation furnace tube large groups are correspondingly arranged on one cross pipe, and M and N are positive integers;

the fuel pipeline comprises a primary fuel main pipe and a secondary fuel branch pipe, wherein at least one primary fuel main pipe is correspondingly arranged on one cross pipe, and the primary fuel main pipe is used for providing fuel for all burners corresponding to all large groups of radiation furnace tubes correspondingly communicated with the cross pipe; one large group of the radiation furnace tubes is correspondingly provided with a secondary fuel branch tube, and the secondary fuel branch tube is used for providing fuel for a burner corresponding to the large group of the radiation furnace tubes; for a single cross pipe, after the plurality of secondary fuel branch pipes corresponding to all the large groups of the radiation furnace pipes correspondingly communicated with the single cross pipe are mutually connected in parallel, the secondary fuel branch pipes are connected in parallel and/or in series with the primary fuel main pipe corresponding to the single cross pipe.

Optionally, one cross pipe is correspondingly provided with M raw material pipelines and N large groups of radiation furnace tubes, M and N are positive integers, M is greater than or equal to 1 and is less than or equal to N, and N is greater than or equal to 1; preferably, 2. Ltoreq. M.ltoreq.4, 2. Ltoreq. N.ltoreq.4.

Optionally, L cross pipes are correspondingly arranged in each furnace, L is an integer greater than or equal to 2 and less than or equal to 4, and is preferably an even number greater than or equal to 2 and less than or equal to 4.

Optionally, for a single cross tube, among all the burners arranged corresponding to the single cross tube, the burner arranged at the bottom of the radiant section hearth, the burner arranged on the side wall of the radiant section hearth, and the burner arranged at the top of the radiant section hearth are respectively and correspondingly provided with one primary fuel main tube.

Optionally, one end of the primary fuel main pipe, which is close to the combustor, is divided into a first secondary main pipe and a second secondary main pipe, the combustor has a primary spray gun and a secondary spray gun, and for a single primary fuel main pipe, the first secondary main pipe is used for supplying fuel to the primary spray guns of all the combustors arranged corresponding to the single primary fuel main pipe, and the second secondary main pipe is used for supplying fuel to the secondary spray guns of all the combustors arranged corresponding to the single primary fuel main pipe; the first sub-main pipe is communicated with at least one secondary fuel branch pipe which is parallel to each other, and the second sub-main pipe is communicated with at least one secondary fuel branch pipe which is parallel to each other.

Optionally, the burner is provided with a first-stage spray gun and a second-stage spray gun, one end of the second-stage fuel branch pipe close to the burner is divided into a first sub branch pipe and a second sub branch pipe, the first sub branch pipe is communicated with the first-stage spray guns of the plurality of burners corresponding to the large group of the radiant furnace pipes, and the second sub branch pipe is communicated with the second-stage spray guns of the plurality of burners corresponding to the large group of the radiant furnace pipes.

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

Optionally, a primary regulating valve is arranged on the primary fuel main pipe, and a secondary regulating valve is arranged on the first sub-branch pipe of the secondary fuel branch pipe.

Optionally, a primary regulating valve is arranged on the primary fuel main pipe, and a secondary regulating valve is arranged on the second sub-branch pipe of the secondary fuel branch pipe.

Optionally, the primary fuel main pipe is further provided with a total heat value controller, and the total heat value controller is configured to monitor an actual total heat release amount after the fuel flowing through the primary fuel main pipe is combusted, and prompt the primary regulating valve to be regulated when an absolute value of a difference between the actual total heat release amount and a theoretical total heat amount is greater than a first preset value, where the theoretical total heat amount is a total heat amount required when a total average temperature of furnace tube outlets of each radiation furnace tube large group correspondingly communicated with a crossover tube corresponding to the primary fuel main pipe reaches a first preset temperature.

Optionally, the secondary fuel branch pipe is further provided with a sub-heating value controller, and the sub-heating value controller is configured to monitor an actual sub-heating value after the fuel flowing through the secondary fuel branch pipe is combusted, and prompt the secondary regulating valve to be regulated when an absolute value of a difference between the actual sub-heating value and a theoretical sub-heating value is greater than a second preset value, where the theoretical sub-heating value is a sub-heating value required when an average temperature of furnace tube outlets of the large group of radiation furnace tubes corresponding to the secondary fuel branch pipe reaches a second preset temperature.

Optionally, one of the large groups of radiation furnace tubes is correspondingly provided with a second-stage temperature controller, and the second-stage temperature controller is configured to monitor an actual average temperature of the outlet of the furnace tube of the large group of radiation furnace tubes, and prompt to adjust a second-stage adjusting valve on a second-stage fuel branch tube corresponding to the large group of radiation furnace tubes when an absolute value of a difference between the actual average temperature of the outlet of the furnace tube and a second preset temperature is greater than a third preset value.

Optionally, one primary temperature controller is correspondingly arranged on one cross pipe, and the primary temperature controller is configured to monitor an actual total average temperature of furnace tube outlets of all radiation furnace tube large groups corresponding to the cross pipe, and prompt to adjust a primary adjusting valve on a primary fuel main pipe corresponding to the cross pipe when an absolute value of a difference between the actual total average temperature of the furnace tube outlets and a first preset temperature is greater than a fourth preset value.

Optionally, a raw material flow regulating valve is arranged on the raw material pipeline;

and the primary temperature controller is also used for prompting to adjust a raw material flow regulating valve on a raw material pipeline corresponding to the crossing pipe when the absolute value of the difference value between the actual furnace tube outlet total average temperature and the first preset temperature is greater than a fourth preset value. In principle, it is ensured that in special cases, such as cracking of the same material, the regulation of the material flow is strictly controlled within a minimum variation range, for example less than 5% between the maximum and minimum values.

Optionally, the cracking furnace further includes a cooling medium pipeline, and the cooling medium pipeline is communicated with the raw material pipeline and/or the cross pipe and is used for injecting a cooling medium into the raw material pipeline and/or the cross pipe.

By the technical scheme, in the cracking furnace provided by the disclosure, a plurality of mutually parallel convection section preheating pipelines communicated with a plurality of mutually parallel raw material pipelines are correspondingly communicated with a plurality of mutually parallel radiation furnace tube large groups through at least one cross pipe, for a single cross pipe, cracking raw materials from different raw material pipelines are preheated by the preheating pipelines and can enter the cross pipe after being mixed in a header or a collector before entering the corresponding radiation furnace tube large group, so that the cracking raw materials entering each radiation furnace tube large group corresponding to the cross pipe have the same original temperature and pressure; meanwhile, each radiation furnace tube large group is correspondingly provided with a secondary fuel branch pipe, and each secondary fuel branch pipe is respectively used for supplying fuel to the combustor corresponding to each radiation furnace tube large group, so that the fuel flow flowing into the combustor corresponding to each radiation furnace tube large group can be accurately regulated and controlled through each secondary fuel branch pipe. Therefore, the cracking furnace can effectively improve the regulation and control accuracy of the average temperature of the furnace tube outlets of the large groups of the radiation furnace tubes. Finally, the cracking raw material entering the radiation section and the dilution steam mixture have the same or the smallest difference of inlet and outlet conditions and residence time as possible, so that the same cracking efficiency and operation period are realized, and the aims of high temperature, short residence time and low hydrocarbon partial pressure are well met.

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. 1 schematically illustrates a schematic structural view of a cracking furnace according to an embodiment of the disclosure;

FIG. 2 schematically illustrates a schematic structural view of another cracking furnace according to an embodiment of the present disclosure;

FIG. 3 schematically illustrates a schematic structural view of yet another cracking furnace according to an embodiment of the present disclosure;

fig. 4 schematically illustrates a structural schematic diagram of yet another cracking furnace according to an embodiment of the present disclosure.

Description of the reference numerals

1. 2 convection section of raw material pipeline

3. Cross pipe 4 radiation section

5. Combustor 6 fuel line

7. 8-stage fuel main pipe of radiation furnace tube large group

9. Secondary fuel branch pipe 10 primary regulating valve

11. Two-stage regulating valve 12 first sub-branch pipe

13. Second branch pipe 14 cooling medium pipeline

Detailed Description

The following detailed description of the embodiments of the disclosure refers to 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.

Existing cracking furnaces include a feedstock conduit, a convection section, a cross-over tube, a radiant section, a burner, and a fuel conduit. A plurality of radiation furnace tube large groups are distributed in the radiation section, each raw material pipeline is communicated with one radiation furnace tube large group through a cross pipe after passing through the convection section, the other end of each raw material pipeline is communicated with a raw material main pipe, and a mass flow meter is arranged on the raw material main pipe or each raw material pipeline and is used for controlling the flow of cracking raw materials entering each radiation furnace tube large group through each raw material pipeline. The combustor sets up lateral wall and the bottom at the radiation section for provide the heat to each radiation boiler tube big group, the fuel conduit includes lateral wall fuel main and bottom fuel main, lateral wall fuel main is used for providing fuel to the lateral wall combustor, bottom fuel main is used for providing fuel to the bottom combustor, be provided with the lateral wall governing valve on the lateral wall fuel main, a total flow of fuel for adjusting supply side wall combustor, be provided with the bottom governing valve on the bottom fuel main, a total flow of fuel for adjusting supply bottom combustor.

The inventor of the present disclosure finds that, in the existing cracking furnace, the average temperature of the furnace tube outlets of each large group of radiant furnace tubes is indirectly regulated by regulating the raw material flow rate flowing through each raw material pipeline and regulating the total combustion flow rate flowing through the side wall fuel main pipe and the bottom fuel main pipe, and such a setting mode has at least the following problems:

(1) The total fuel flow supplied to the side wall burners and the bottom burners is regulated, so that the total average temperature of the furnace tube outlets of all the large groups of the radiation furnace tubes can be regulated only, the average temperature of the furnace tube outlets of each large group of the radiation furnace tubes cannot be regulated, and the average temperature of the furnace tube outlets of each large group of the radiation furnace tubes can be greatly different due to the fact that the combustion conditions of the burners corresponding to the large groups of the radiation furnace tubes are possibly different;

(2) The difference between the average temperatures of the furnace tube outlets of the radiation furnace tube large groups needs to be eliminated by regulating and controlling the raw material flow in the corresponding raw material pipelines, which can cause the difference of the raw material flow, the inlet pressure, the inlet temperature, the retention time and the like entering the radiation furnace tube large groups, further cause the cracking depths of the cracking raw materials among different groups to be different, further cause the coking of the radiation furnace tubes, shorten the operation period of the radiation furnace tubes of the cracking furnace, increase the coke cleaning times, influence the production benefit of the device, and the regulation of the raw material flow is limited by the distribution bias flow of the venturi of the furnace tube inlet of the radiation section, namely the regulation range of the raw material flow is limited, so that the raw materials in each group of radiation furnace tubes cannot be ensured to have the same or similar cracking depths;

(3) The arrangement quantity of the cross pipes is large, usually one raw material pipeline is communicated with one radiation furnace pipe large group through one cross pipe, when raw materials in each raw material pipeline flow through the convection section, the heat absorbed by the raw materials in each raw material pipeline in the preheating process is possibly different due to the influence of smoke flow deviation and raw material flow difference in the convection section, so that the initial temperature of the raw materials entering each radiation furnace pipe large group through each cross pipe is deviated, and the average temperature of the furnace pipe outlet of each radiation furnace pipe large group is greatly different;

(4) When one cracking furnace is used for cracking multiple cracking raw materials at the same time, different radiation furnace tube large groups need to crack different cracking raw materials, and because the cracking performance difference of different cracking raw materials is large, different furnace tube outlet average temperatures need to be set for the radiation furnace tube large groups for cracking different cracking raw materials, so that the different cracking raw materials have proper cracking depth, which is difficult to realize by the existing cracking furnace;

(5) In practical application, in order to improve the on-line rate of the cracking furnace, a large group of partial radiation furnace tubes is required to be cracked, and a large group of partial radiation furnace tubes is required to be decoked, so that different average furnace tube outlet temperatures are required to be set for the large group of the cracking side radiation furnace tubes and the large group of the decoking side radiation furnace tubes, and the requirement is difficult to realize in the existing cracking furnace.

(6) Because the prior art can cause the drift of the venturi due to the different and worst flow of raw materials, and the different temperatures entering the radiant section, the coking can be caused to be different, and the pressure drop in the radiant furnace tube is different as a result.

Due to the above problems, the objectives of "high temperature, short residence time and low hydrocarbon partial pressure" are not well achieved, resulting in a decrease in cracking efficiency (olefin yield and selectivity) and a reduction in the operating cycle of the cracking furnace.

In order to solve the above problems, the present disclosure provides a cracking furnace. The cracking furnace can comprise a raw material pipeline 1, a convection section 2, a cross pipe 3, a radiation section 4, a burner 5 and a fuel pipeline 6, wherein a plurality of mutually parallel preheating pipelines are arranged in the convection section 2, a plurality of radiation furnace tube large groups 7 are distributed in the radiation section 4, one radiation furnace tube large group 7 consists of at least one radiation furnace tube small group, the burner 5 is arranged at least one position of the bottom, the side wall or the top of the radiation section 4, and the arrangement position of the burner 5 enables one radiation furnace tube large group 7 to correspond to at least one burner 5;

one raw material pipeline 1 is communicated with at least one preheating pipeline in the convection section 2, a plurality of mutually parallel preheating pipelines are communicated with a plurality of mutually parallel radiation furnace tube large groups 7 in the same radiation furnace chamber through at least one cross pipe 3, wherein M raw material pipelines 1 and N radiation furnace tube large groups 7 are correspondingly arranged on one cross pipe 3, and M and N are positive integers;

the fuel pipeline 6 comprises a primary fuel main pipe 8 and a secondary fuel branch pipe 9, at least one primary fuel main pipe 8 is correspondingly arranged on one cross pipe 3, and the primary fuel main pipe 8 is used for supplying fuel to all burners 5 corresponding to all large groups 7 of radiation furnace tubes correspondingly communicated with the cross pipe 3; a secondary fuel branch pipe 9 is correspondingly arranged on one large group 7 of the radiation furnace pipes, and the secondary fuel branch pipe 9 is used for supplying fuel to the burner 5 corresponding to the large group 7 of the radiation furnace pipes; for a single cross pipe 3, a plurality of secondary fuel branch pipes 9 corresponding to all the large groups 7 of radiant furnace pipes correspondingly communicated with the single cross pipe 3 are connected in parallel and/or in series with the primary fuel main pipe 8 corresponding to the single cross pipe 3.

In the present disclosure, specifically, a plurality of mutually parallel raw material pipelines are communicated with a plurality of mutually parallel preheating pipelines in a convection section, the plurality of mutually parallel preheating pipelines are correspondingly communicated with a plurality of mutually parallel radiation furnace tube large groups through a cross tube, and for a single cross tube, cracking raw materials from the plurality of raw material pipelines are preheated in the convection section preheating pipelines, mixed in a header or a manifold before entering each radiation furnace tube large group, and then enter each radiation furnace tube large group corresponding to the cross tube from the cross tube. Aiming at a single cross pipe, the fuel from a boundary area firstly enters a corresponding primary fuel main pipe, then is shunted to enter each secondary fuel branch pipe corresponding to each radiation furnace tube large group according to actual needs, and finally is shunted to enter each combustor corresponding to each radiation furnace tube large group from each secondary fuel branch pipe.

The cracking furnace disclosed by the invention can at least realize the following effects:

(1) The purpose of adjusting the total average temperature of the furnace tube outlets of a plurality of radiation furnace tube large groups corresponding to the cross tubes corresponding to the primary fuel main tube can be achieved by adjusting the fuel flow flowing through the primary fuel main tube;

(2) The fuel flow passing through each secondary fuel branch pipe can be adjusted, so that the deviation of the average temperature of the furnace tube outlets among the large groups of the radiation furnace tubes approaches to zero, thereby being beneficial to the long-period stable operation of the cracking furnace, prolonging the service life of the radiation furnace tubes and improving the stability of the product quality;

(3) The arrangement quantity of the cross tubes is reduced, and the cracking raw materials from a plurality of raw material pipelines can be mixed before entering each large group of the radiation furnace tubes, so that the cracking raw materials entering each large group of the radiation furnace tubes have the same original temperature, pressure and flow, and the deviation between the average temperatures of the furnace tube outlets of each large group of the radiation furnace tubes is further reduced;

(4) Under the condition that different radiation furnace tube large groups are used for cracking different cracking raw materials, the fuel flow passing through the primary fuel branch tube and each secondary fuel branch tube is adjusted, so that the radiation furnace tube large groups for cracking the different cracking raw materials have different average furnace tube outlet temperatures, and the different cracking raw materials can be ensured to keep proper cracking depth during cracking, thereby overcoming the influence of grouping cracking of the different cracking raw materials on the cracking furnace, and realizing the maximization of the income of a target cracking product and the stable operation of the cracking furnace;

(5) Under the condition that a large group of radiation furnace tubes corresponding to one cross tube is cracked, and simultaneously, a large group of another radiation furnace tube is decoked, the large group of radiation furnace tubes at the cracking side and the large group of the decoking side have different average temperatures of furnace tube outlets by adjusting the fuel flow passing through an adjusting valve of a primary fuel main tube and each secondary fuel branch tube, so that the single decoking condition of a part of large groups of radiation furnace tubes is realized under the condition that the integral operation of the cracking furnace is not influenced, the online rate of the cracking furnace can be obviously improved, and the benefit maximization of the cracking furnace is realized;

(6) The raw materials corresponding to one cross tube are adjusted in a small range, and the deviation of the average temperature of each large group of radiation furnace tubes corresponding to different cross tubes when the same raw materials are cracked is ensured by adjusting the raw materials simultaneously, so that the working conditions that different cross tubes correspond to different radiation section furnace tubes crack different raw materials or are burnt can be better adapted, the various conditions can be met, and the operation is more flexible.

According to the disclosure, in the cracking furnace, M raw material pipelines 1 and N radiation furnace tube large groups 7 can be correspondingly arranged on one cross tube 3, wherein M and N are positive integers, M is more than or equal to 1 and less than or equal to N, and N is more than or equal to 1; preferably, 2. Ltoreq. M.ltoreq.4, 2. Ltoreq. N.ltoreq.4.

According to the disclosure, L transverse pipes 3 are correspondingly arranged in each hearth, L is an integer greater than or equal to 2 and less than or equal to 4, and is preferably an even number greater than or equal to 2 and less than or equal to 4.

According to the present disclosure, for a single cross tube, among all the burners disposed corresponding to the single cross tube, the burner disposed at the bottom of the hearth of the radiant section, the burner disposed at the side wall of the hearth of the radiant section, and the burner disposed at the top of the hearth of the radiant section may be respectively disposed with one primary fuel main tube.

In the present disclosure, at least the following adjustment modes can be realized through the primary fuel main pipe: independently adjusting fuel gas of a burner at the bottom of the hearth of the radiation section; independently adjusting fuel gas of a burner on the side wall of the hearth of the radiation section; independently adjusting fuel gas of a burner at the top of the radiant section hearth; regulating fuel gas of burners at any two positions of the bottom, the side wall and the top of the hearth of the radiation section; meanwhile, the fuel gas of the burners at the bottom, the side wall and the top of the hearth of the radiation section is regulated.

According to the present disclosure, one end of the primary fuel main pipe close to the burner may be divided into a first sub main pipe and a second sub main pipe, the burner has a primary lance and a secondary lance, and for a single primary fuel main pipe, the first sub main pipe is configured to provide fuel to the primary lances of all the burners corresponding to the single primary fuel main pipe, and the second sub main pipe is configured to provide fuel to the secondary lances of all the burners corresponding to the single primary fuel main pipe; the first sub-main pipe is communicated with at least one secondary fuel branch pipe which is parallel to each other, and the second sub-main pipe is communicated with at least one secondary fuel branch pipe which is parallel to each other.

According to the present disclosure, the burner 5 may be provided with a first-stage lance and a second-stage lance, one end of the second-stage fuel branch pipe 9 close to 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 communicated with the first-stage lances of the plurality of burners 5 corresponding to the large group 7 of radiant tubes, and the second sub-branch pipe 13 is communicated with the second-stage lances of the plurality of burners 5 corresponding to the large group 7 of radiant tubes.

According to the present disclosure, in order to more conveniently realize the regulation and control of the fuel flow rate flowing 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, a primary regulating valve 10 is arranged on the primary fuel main pipe 8, and a secondary regulating valve 11 is arranged on the first sub-branch pipe 12 of the secondary fuel branch pipe 9; or, a primary regulating valve 10 is arranged on the primary fuel main pipe 8, and a secondary regulating valve 11 is arranged on the second sub-branch pipe 13 of the secondary fuel branch pipe 9.

In the present disclosure, the following three adjustment modes are realized by adjusting the secondary adjustment valve mind: regulating fuel gas corresponding to a large group of single-group radiation furnace tubes; adjusting fuel gas corresponding to a primary fuel gun of a large group corresponding to a single group of radiation furnace tubes; regulating the fuel gas corresponding to the secondary fuel gun of the large group of the single group of the radiation furnace tubes.

According to the disclosure, the primary fuel main pipe 8 may further be provided with a total heat value controller, and the total heat value controller is configured to monitor an actual total heat release amount after the fuel flowing through the primary fuel main pipe 8 is combusted, and prompt the primary regulating valve 10 to be regulated when an absolute value of a difference between the actual total heat release amount and a theoretical total heat amount is greater than a first preset value, where the theoretical total heat amount is a total heat amount required when a total average temperature of furnace tube outlets of each radiation furnace tube large group 7 correspondingly communicated with the crossover pipe 3 corresponding to the primary fuel main pipe 8 reaches a first preset temperature.

In the present disclosure, in particular, the primary fuel main pipe is used for providing all the large groups of radiant coils corresponding to a single cross pipe with the fuel required for cracking the raw material, and after the fuel enters the burner for combustion, the provided heat can make the total average temperature of the coil outlets of all the large groups of radiant coils corresponding to the single cross pipe reach a first preset temperature.

The total average temperature of the furnace tube outlets refers to the arithmetic average value of the average temperature of the furnace tube outlets of each large group of the radiation furnace tubes, the first preset temperature can be set according to the types of the cracking raw materials in each large group of the radiation furnace tubes, and the setting aims to ensure that the cracking raw materials in all the large groups of the radiation furnace tubes have proper cracking depth.

According to the disclosure, the secondary fuel branch pipe 9 may further be provided with a sub-heating value controller, and the sub-heating value controller is configured to monitor an actual sub-heating value after the fuel flowing through the secondary fuel branch pipe 9 is combusted, and prompt the secondary regulating valve 11 to be regulated when an absolute value of a difference between the actual sub-heating value and a theoretical sub-heating value is greater than a second preset value, where the theoretical sub-heating value refers to a sub-heating value required when an average temperature of furnace tube outlets of the radiation furnace tube main group 7 corresponding to the secondary fuel branch pipe 9 reaches a second preset temperature.

In the present disclosure, in particular, the secondary fuel branch pipe is used for providing the fuel required for cracking the raw material for the single radiation furnace tube large group, and after the fuel enters the burner for combustion, the provided heat can enable the average temperature of the furnace tube outlet of the single radiation furnace tube large group to reach a second preset temperature.

The average temperature of the furnace tube outlet refers to the arithmetic average value of the average temperatures of the furnace tube outlets of the small groups of the radiation furnace tubes forming the large group of the radiation furnace tubes, the second preset temperature can be set according to the type of the cracking raw materials in the large group of the radiation furnace tubes, and the setting aims to enable the cracking raw materials in the large group of the radiation furnace tubes to have proper cracking depth. Optionally, the second preset temperatures corresponding to the radiation furnace tube large groups for cracking the same cracking raw material are the same, and the second preset temperatures corresponding to the radiation furnace tube large groups for cracking different cracking raw materials may be different from each other.

Further, for a single cross tube, the arithmetic mean of the second preset temperatures corresponding to all the radiation furnace tube large groups corresponding to the single cross tube is the first preset temperature corresponding to the single cross tube.

According to the disclosure, one of the radiation furnace tube large groups can be correspondingly provided with a second-stage temperature controller, and the second-stage temperature controller is used for monitoring the actual furnace tube outlet average temperature of the radiation furnace tube large group and prompting to adjust a second-stage adjusting valve on a second-stage fuel branch tube corresponding to the radiation furnace tube large group when the absolute value of the difference value between the actual furnace tube outlet average temperature and the second preset temperature is larger than a third preset value.

According to the disclosure, one cross pipe can be correspondingly provided with one primary temperature controller, and the primary temperature controller is used for monitoring the actual furnace tube outlet total average temperature of all radiation furnace tube large groups corresponding to the cross pipe, and prompting to adjust the primary regulating valve on the primary fuel main pipe corresponding to the cross pipe when the absolute value of the difference value between the actual furnace tube outlet total average temperature and the first preset temperature is greater than a fourth preset value.

According to the present disclosure, a raw material flow regulating valve is provided on the raw material pipeline; the first-stage temperature controller can be further used for prompting to adjust a raw material flow regulating valve on a raw material pipeline corresponding to the crossing pipe when the absolute value of the difference value between the actual furnace tube outlet total average temperature and the first preset temperature is larger than a fourth preset value.

According to the present disclosure, the cracking furnace further includes a temperature reducing medium pipeline 14, and the temperature reducing medium pipeline 14 is communicated with the raw material pipeline 1 and/or the cross pipe 3, and is used for injecting a temperature reducing medium into the raw material pipeline 1 and/or the cross pipe 3.

In the present disclosure, the cooling medium may be cooling water, and the cooling water may be boiler feed water or desalted water. The cooling medium pipeline can be arranged at any position of an inlet, an outlet or the middle of the upper mixing heat exchange module, and is preferably arranged between the outlet of the upper mixing superheat section module and the lower mixing superheater module in the convection section. And the cooling medium pipeline is used for injecting a cooling medium into the material pipeline and/or the cross pipe when the temperature of the raw material entering each large group of radiation furnace tubes is too high or different large groups of radiation furnace tubes are in different working conditions. For example, when a part of the large group of the radiation furnace tubes is used for cracking and a part of the large group of the radiation furnace tubes is used for decoking or hot preparation, the cooling medium can be injected into the large group of the radiation furnace tubes for decoking or hot preparation through the cooling medium pipeline.

Fig. 1 schematically shows a structural schematic diagram of a cracking furnace according to an embodiment of the present disclosure, as shown in fig. 1, in the cracking furnace, 6 large groups 7 of radiant furnace tubes are arranged in each furnace chamber of a radiant section 4,2 cross-over tubes 3 (only one is shown in the figure) are arranged in each furnace chamber, each cross-over tube 3 corresponds to 3 large groups 7 of radiant furnace tubes, 1 main primary fuel tube 8 and 3 secondary fuel branch tubes 9, wherein 3 secondary fuel branch tubes 9 are divided into 3 first sub-branch tubes 12 and 3 second sub-branch tubes 13, the first sub-branch tubes 12 go to primary lances of a bottom burner 5, and the second sub-branch tubes 13 go to secondary lances of the bottom burner 5.

The fuel gas flow is fine tuned to reduce the variation in the average coil outlet temperature (COT-A) of a single large group 7 of radiant coils when cracking the same feedstock by means of a secondary regulating valve 11 located in a second branch 13 to the secondary lance. Meanwhile, the total fuel flow is adjusted through a primary adjusting valve 10 arranged on a primary fuel main pipe 8, so that the adjustment of the average temperature of the furnace tube outlets (COT-G) of a plurality of radiation furnace tube large groups 7 corresponding to each cross tube 3 is realized.

Fig. 2 schematically shows a structural schematic diagram of another cracking furnace according to an embodiment of the present disclosure, as shown in fig. 2, in the cracking furnace, 6 large groups 7 of radiant furnace tubes are arranged in each furnace chamber of the radiant section 4, 3 cross-over tubes 3 (only one is shown in the figure) are arranged in each furnace chamber, each cross-over tube 3 corresponds to 2 large groups 7 of radiant furnace tubes, 1 main primary fuel tube 8 and 2 secondary fuel branch tubes 9, wherein 2 secondary fuel branch tubes 9 are divided into 2 first sub-branch tubes 12 and 2 second sub-branch tubes 13, the first sub-branch tubes 12 go to primary lances of the bottom burner 5, and the second sub-branch tubes 13 go to secondary lances of the bottom burner 5.

The fuel gas flow is fine tuned to reduce the variation in the average coil outlet temperature (COT-A) of a single large group 7 of radiant coils when cracking the same feedstock by means of a secondary regulating valve 11 located in a second branch 13 to the secondary lance. Meanwhile, the total fuel flow is adjusted through a primary adjusting valve 10 arranged on a primary fuel main pipe 8, so that the adjustment of the average temperature of the furnace tube outlets (COT-G) of a plurality of radiation furnace tube large groups 7 corresponding to each cross tube 3 is realized.

Fig. 3 schematically shows a structural schematic diagram of another cracking furnace according to an embodiment of the present disclosure, as shown in fig. 3, in the cracking furnace, 6 large groups 7 of radiant furnace tubes are arranged in each furnace chamber of the radiant section 4,2 cross-over tubes 3 (only one is shown in the figure) are arranged in each furnace chamber, each cross-over tube 3 corresponds to 3 large groups 7 of radiant furnace tubes, 1 main primary fuel tube 8 and 3 secondary fuel branch tubes 9, and the secondary fuel branch tubes 9 go to the bottom burner 5.

The flow of the fuel gas is finely adjusted by a secondary regulating valve 11 arranged on a secondary fuel branch pipe 9 so as to reduce the deviation of the average temperature of the furnace tube outlets (COT-A) of a single large group 7 of radiation furnace tubes when the same raw material is cracked. Meanwhile, the total fuel flow is adjusted through a primary adjusting valve 10 arranged on a primary fuel main pipe 8, so that the adjustment of the average temperature of the furnace tube outlets (COT-G) of a plurality of radiation furnace tube large groups 7 corresponding to each cross tube 3 is realized.

Fig. 4 schematically shows a structural schematic diagram of another cracking furnace according to an embodiment of the present disclosure, as shown in fig. 4, in the cracking furnace, each furnace in the radiant section 4 is provided with 6 radiant furnace tube macro-groups 7, each furnace is provided with 2 cross-over tubes 3 (only one is shown in the figure), each cross-over tube 3 corresponds to 3 radiant furnace tube macro-groups 7 and 1 primary fuel main tube 8, the primary fuel main tube 8 is divided into two primary fuel branch tubes, one primary fuel branch tube goes to the bottom combustion system, the other primary fuel branch tube goes to the sidewall combustion system, the primary fuel branch tube of the bottom combustion system is divided into 3 secondary fuel branch tubes 9 and goes to the bottom burner 5, and the primary fuel branch tube of the sidewall combustion system is divided into 3 secondary fuel branch tubes 9 and goes to the sidewall burner 5.

The flow of the fuel gas is finely adjusted by the secondary regulating valves 11 arranged on the secondary fuel branch pipes 9 at the bottom and on the side wall so as to reduce the deviation of the average temperature of the furnace tube outlets (COT-A) of the large group 7 of single radiant furnace tubes when cracking the same raw material. Meanwhile, the total fuel flow is adjusted through a primary adjusting valve 10 arranged on a primary fuel main pipe 8, so that the adjustment of the average temperature of the furnace tube outlets (COT-G) of a plurality of radiation furnace tube large groups 7 corresponding to each cross tube 3 is realized.

The preferred embodiments of the present disclosure are described in detail above with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details in the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that, in the above embodiments, the various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations will not be further described in the present disclosure.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims (15)

1. A cracking furnace is characterized by comprising a raw material pipeline, a convection section, a cross pipe, a radiation section, a burner and a fuel pipeline, wherein a plurality of mutually parallel preheating pipelines are arranged in the convection section, a plurality of radiation furnace tube large groups are distributed in the radiation section, one radiation furnace tube large group consists of at least one radiation furnace tube small group, the burner is arranged at least one position of the bottom, the side wall or the top of the radiation section, and the burner is arranged at a position which enables one radiation furnace tube large group to correspond to at least one burner;

the raw material pipeline is communicated with at least one preheating pipeline in the convection section, the plurality of mutually parallel preheating pipelines are communicated with a plurality of mutually parallel radiation furnace tube large groups in the same radiation hearth through at least one cross pipe, wherein M raw material pipelines and N radiation furnace tube large groups are correspondingly arranged on one cross pipe, and M and N are positive integers;

the fuel pipeline comprises a primary fuel main pipe and a secondary fuel branch pipe, wherein at least one primary fuel main pipe is correspondingly arranged on one cross pipe, and the primary fuel main pipe is used for providing fuel for all burners corresponding to all large groups of radiation furnace tubes correspondingly communicated with the cross pipe; a second-stage fuel branch pipe is correspondingly arranged on one large group of the radiation furnace tubes and used for providing fuel for a burner corresponding to the large group of the radiation furnace tubes; for a single cross pipe, after the plurality of secondary fuel branch pipes corresponding to all the large groups of the radiation furnace pipes correspondingly communicated with the single cross pipe are mutually connected in parallel, the secondary fuel branch pipes are connected in parallel and/or in series with the primary fuel main pipe corresponding to the single cross pipe.

2. The cracking furnace according to claim 1, wherein M raw material pipelines and N large groups of the radiation furnace tubes are correspondingly arranged on one cross tube, M and N are positive integers, M is more than or equal to 1 and less than or equal to N, and N is more than or equal to 1; preferably, 2. Ltoreq. M.ltoreq.4, 2. Ltoreq. N.ltoreq.4.

3. The cracking furnace according to claim 1, wherein L cross pipes are correspondingly arranged in each hearth, and 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.

4. The cracking furnace according to claim 1, wherein for a single cross tube, among all the burners disposed corresponding to the single cross tube, one primary fuel main tube is disposed corresponding to each of the burner disposed at the bottom of the radiant section hearth, the burner disposed at the side wall of the radiant section hearth, and the burner disposed at the top of the radiant section hearth.

5. The cracking furnace according to claim 1, wherein the end of the primary fuel main near the burner is divided into a first sub-main and a second sub-main, the burner has a primary lance and a secondary lance, and for a single primary fuel main, the first sub-main is used for supplying fuel to the primary lances of all burners corresponding to the single primary fuel main, and the second sub-main is used for supplying fuel to the secondary lances of all burners corresponding to the single primary fuel main; the first sub-main pipe is communicated with at least one secondary fuel branch pipe which is parallel to each other, and the second sub-main pipe is communicated with at least one secondary fuel branch pipe which is parallel to each other.

6. The cracking furnace of claim 1, wherein the burners are provided with a primary lance and a secondary lance, and one end of the secondary fuel branch pipe close to the burners is divided into a first sub-branch pipe and a second sub-branch pipe, the first sub-branch pipe is communicated with the primary lances of the plurality of burners corresponding to the large group of radiant tubes, and the second sub-branch pipe is communicated with the secondary lances of the plurality of burners corresponding to the large group of radiant tubes.

7. The cracking furnace of claim 6, wherein the primary fuel main pipe is provided with a primary regulating valve, and the secondary fuel branch pipe is provided with a secondary regulating valve.

8. The cracking furnace of claim 6, wherein the primary fuel main pipe is provided with a primary regulating valve, and the first sub-branch pipe of the secondary fuel branch pipe is provided with a secondary regulating valve.

9. The cracking furnace of claim 6, wherein the primary fuel main pipe is provided with a primary regulating valve, and the second sub-branch pipe of the secondary fuel branch pipe is provided with a secondary regulating valve.

10. The cracking furnace according to any one of claims 7 to 9, wherein the primary fuel main pipe is further provided with a total heat value controller, and the total heat value controller is configured to monitor an actual total heat release amount after the fuel flowing through the primary fuel main pipe is combusted, and prompt the primary regulating valve to be adjusted when an absolute value of a difference between the actual total heat release amount and a theoretical total heat amount is greater than a first preset value, wherein the theoretical total heat amount is a total heat amount required when a furnace tube outlet total average temperature of each radiant furnace tube large group correspondingly communicated with the crossover tube corresponding to the primary fuel main pipe reaches a first preset temperature.

11. The cracking furnace according to any one of claims 7 to 9, wherein the secondary fuel branch pipe is further provided with a sub-heating value controller, and the sub-heating value controller is configured to monitor an actual sub-heating value after the fuel flowing through the secondary fuel branch pipe is combusted, and prompt the secondary regulating valve to adjust when an absolute value of a difference between the actual sub-heating value and a theoretical sub-heating value is greater than a second preset value, wherein the theoretical sub-heating value refers to a sub-heating value required when an average temperature of furnace tube outlets of the radiation furnace tube main group corresponding to the secondary fuel branch pipe reaches a second preset temperature.

12. The cracking furnace according to any one of claims 7 to 9, wherein one of the radiation furnace tube large groups is provided with a second-stage temperature controller, and the second-stage temperature controller is configured to monitor an actual furnace tube outlet average temperature of the radiation furnace tube large group, and prompt adjustment of a second-stage regulating valve on a second-stage fuel branch tube corresponding to the radiation furnace tube large group when an absolute value of a difference between the actual furnace tube outlet average temperature and a second preset temperature is greater than a third preset value.

13. The cracking furnace of claim 12, wherein one primary temperature controller is disposed for each cross tube, and the primary temperature controller is configured to monitor the actual overall average furnace tube outlet temperature of all the large groups of radiant furnace tubes corresponding to the cross tube, and prompt adjustment of the primary regulating valve on the primary fuel main tube corresponding to the cross tube when the absolute value of the difference between the actual overall average furnace tube outlet temperature and the first preset temperature is greater than a fourth preset value.

14. The cracking furnace of claim 13, wherein the raw material pipeline is provided with a raw material flow regulating valve;

and the primary temperature controller is also used for prompting to adjust a raw material flow regulating valve on a raw material pipeline corresponding to the crossing pipe when the absolute value of the difference value between the actual furnace tube outlet total average temperature and the first preset temperature is greater than a fourth preset value.

15. The cracking furnace of claim 1, further comprising a temperature reducing medium conduit in communication with the feed conduit and/or the cross-over pipe for injecting a temperature reducing medium into the feed conduit and/or the cross-over pipe.

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