Automatic blowing execution system and method for feeding pipeline of ethylene cracking furnace

Abstract

The invention relates to the technical field of petrochemical engineering, in particular to an ethylene cracking furnace feeding pipeline purging automatic execution system and method.The system comprises a pre-purging state confirmation module used for confirming initial parameters and the initial state of a cracking furnace before purging; when the initial parameter is within the initial range and the initial state of the cracking furnace reaches the purging condition, it is indicated that the feeding pipeline can be purged; the feeding pipeline purging process intelligent control module is used for controlling purging process key parameters, gas-phase feeding equipment and liquid-phase feeding equipment in the purging stage of the feeding pipeline and sending out a control instruction, and the purging process key parameters comprise the outlet temperature of the cracking furnace and the oxygen content of a hearth; and the purging execution module is used for purging according to the control instruction of the feeding pipeline purging process intelligent control module in the purging stage. By applying the system, the stability of the system in the blowing process of the feeding pipeline can be effectively improved, and the system has the advantages of high blowing efficiency and high safety.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical engineering, and particularly to an automatic execution system and method for purging the feed pipeline of an ethylene cracking furnace. Background Art

[0002] Ethylene is an important basic raw material in petrochemical engineering and is also one of the petrochemical products with the largest demand and production volume. Its output, scale, and technical level mark the development level of a country's petrochemical industry. The tubular cracking furnace is used for hydrocarbon cracking and is the core device for producing ethylene, determining the production capacity, stable operation, and overall energy consumption of the entire ethylene plant. When hydrocarbon steam cracking reaction occurs in the radiation section of the tubular cracking furnace, coke accumulation will occur on the inner wall of the furnace tube due to secondary reactions such as polymerization and condensation, forming coking. When the coking causes the outer wall temperature of the radiation section furnace tube or the outlet temperature of the quench boiler to reach the production tolerance limit or the pressure difference before and after the venturi tube reaches the production limit, it will seriously affect the production of ethylene, resulting in a decrease in ethylene yield, an increase in energy consumption, a shortening of the furnace tube life, and even affecting production safety.

[0003] Due to the coking characteristics of the ethylene cracking furnace, in the actual application process, it is necessary to frequently and intermittently perform operations such as furnace chamber feed withdrawal and feed pipeline purging on the cracking furnace. At present, most of the feed pipeline purging processes of domestic ethylene cracking furnaces are still manually controlled. Manual purging of the feed pipeline requires technicians to operate frequently, with a large labor intensity, and completely relies on personal experience and the responsibility of the operators. Therefore, the misoperation rate is high. At the same time, manual operation occupies a large amount of normal production time of the ethylene plant, indirectly resulting in a decrease in ethylene production. In addition, due to the different experiences of operators, during the feed pipeline purging process, not only is it easy to have oil in the feed pipeline and repeatedly purge due to unqualified purging, but it is also extremely easy to cause large fluctuations in parameters such as the outlet temperature of the cracking furnace, resulting in an increase in the CO content in the cracked gas. In severe cases, it will cause the ethylene plant to shut down unexpectedly, affecting the long-term safe and stable operation of the plant and resulting in a decrease in ethylene production.

[0004] Therefore, there is an urgent need for an automatic execution system and method for purging the feed pipeline of an ethylene cracking furnace. Summary of the Invention

[0005] In order to solve the problems in the prior art that manual purging of the feed pipeline for an ethylene cracking furnace has low purging efficiency, poor system stability and safety during the purging process, and affects ethylene production, the present invention provides an automatic execution system and method for purging the feed pipeline of an ethylene cracking furnace.

[0006] In order to achieve the above object, the first aspect of the present invention provides an automatic execution system for purging the feed pipeline of an ethylene cracking furnace, the system comprising:

[0007] The pre-purging status confirmation module is used to confirm the initial parameters and the initial status of the cracking furnace before purging. When the initial parameters are within the initial range and the initial status of the cracking furnace meets the purging conditions, it indicates that the feed pipeline purging can be carried out. When the initial parameters are not within the initial range and / or the initial status of the cracking furnace does not meet the purging conditions, an alarm is given.

[0008] The intelligent control module for the feed pipeline purging process is used to control the key parameters of the purging process, as well as the gas-phase feed equipment and the liquid-phase feed equipment during the feed pipeline purging stage, and issue control instructions. Among them, the key parameters of the purging process include the cracking furnace outlet temperature and the furnace chamber oxygen content.

[0009] The purging execution module is used to perform purging according to the control instructions of the intelligent control module for the feed pipeline purging process during the feed pipeline purging stage.

[0010] Preferably, when the initial parameters are not within the initial range, giving an alarm specifically includes:

[0011] When the initial parameters are not within the initial range, an alarm prompt is given for one or more of the initial parameters that are not within the initial range.

[0012] Preferably, the initial parameters include the cross-section pressure, the cracking furnace outlet temperature, the fuel gas pressure, and the dilution steam flow rate.

[0013] Preferably, the initial range of the cross-section pressure is 0.10 - 0.35 MPa, the initial range of the cracking furnace outlet temperature is 720 - 750 °C, the initial range of the fuel gas pressure is 0.08 - 0.25 MPa, and the initial range of the dilution steam flow rate is 3500 - 4500 kg / h.

[0014] Preferably, the initial status of the cracking furnace meeting the purging conditions specifically includes:

[0015] The first feed root valve at the feed root of the cracking furnace has been closed, and the purging steam condensate drainage and warm-up of the gas-phase feed equipment and the liquid-phase feed equipment are qualified.

[0016] Preferably, during the feed pipeline purging stage, controlling the key parameters of the purging process and issuing control instructions specifically includes:

[0017] Control the oxygen content in the furnace within a set oxygen content range. When the oxygen content in the furnace is lower than the lower limit value of the set oxygen content range, open the damper by a first damper amplitude. If the oxygen content in the furnace is still lower than the lower limit value of the set oxygen content range after a set time, continue to open the damper by the first damper amplitude until the oxygen content in the furnace is within the set oxygen content range; when the oxygen content in the furnace is higher than the upper limit value of the set oxygen content range, close the damper by a second damper amplitude. If the oxygen content in the furnace is still higher than the upper limit value of the set oxygen content range after a set time, continue to close the damper by the second damper amplitude until the oxygen content in the furnace is within the set oxygen content range;

[0018] Cascade control the outlet temperature of the cracking furnace and the calorific value of the fuel gas, and control the outlet temperature of the cracking furnace within a set temperature range. When the outlet temperature of the cracking furnace is lower than the lower limit value of the set temperature range, the calorific value of the fuel gas rises at a first calorific value rate. If the outlet temperature of the cracking furnace is still lower than the lower limit value of the set temperature range after a set time, the calorific value of the fuel gas continues to rise at the first calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; when the outlet temperature of the cracking furnace is lower than the first lower limit value, the calorific value of the fuel gas rises at a second calorific value rate. If the outlet temperature of the cracking furnace is still lower than the first lower limit value after a set time, the calorific value of the fuel gas continues to rise at the second calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; wherein, the first lower limit value is less than the lower limit value of the set temperature range and the difference between the two is 2 - 10°C;

[0019] When the outlet temperature of the cracking furnace is higher than the upper limit value of the set temperature range, the calorific value of the fuel gas drops at a third calorific value rate. If the outlet temperature of the cracking furnace is still higher than the upper limit value of the set temperature range after a set time, the calorific value of the fuel gas continues to drop at the third calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; when the outlet temperature of the cracking furnace is higher than the first upper limit value, the calorific value of the fuel gas drops at a fourth calorific value rate. If the outlet temperature of the cracking furnace is still higher than the first upper limit value after a set time, the calorific value of the fuel gas continues to drop at the fourth calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; wherein, the first upper limit value is greater than the upper limit value of the set temperature range and the difference between the two is 2 - 10°C.

[0020] Preferably, the set oxygen content range is 0 - 10%, the first damper amplitude and the second damper amplitude are 0.1 - 5%, the set temperature range is 710 - 760°C, the first calorific value rate, the second calorific value rate, the third calorific value rate and the fourth calorific value rate are 0 - 5 MW, and the set time is 0.1 - 5 min.

[0021] Preferably, during the purging stage of the feed pipeline, the gas-phase feed equipment and the liquid-phase feed equipment are controlled and control instructions are issued, specifically including:

[0022] When the feed to the cracking furnace hearth is liquid-phase feed, first purge the liquid-phase feed pipeline of the liquid-phase feed equipment, and then purge the gas-phase feed pipeline of the gas-phase feed equipment;

[0023] When the feed to the cracking furnace hearth is gas-phase feed, first purge the gas-phase feed pipeline of the gas-phase feed equipment, and then purge the liquid-phase feed pipeline of the liquid-phase feed equipment.

[0024] Preferably, the purging of the liquid-phase feed pipeline of the liquid-phase feed equipment specifically includes:

[0025] Open the regulating valves of all liquid-phase feed pipelines to the first liquid-phase opening at the first liquid-phase valve rate, then fully open the regulating valve of the first liquid-phase feed pipeline at the second liquid-phase valve rate, purge for the first set purge time, after the purging is completed, close the regulating valve of the first liquid-phase feed pipeline to the first liquid-phase opening at the third liquid-phase valve rate, and at the same time fully open the regulating valve of the second liquid-phase feed pipeline at the second liquid-phase valve rate, purge for the first set purge time until all liquid-phase feed pipelines are purged; after all liquid-phase feed pipelines are purged and it is confirmed that the convection section process is changed to gas phase, control the regulating valves of all liquid-phase feed pipelines to close at the first liquid-phase valve rate.

[0026] Preferably, the purging of the gas-phase feed pipeline of the gas-phase feed equipment specifically includes:

[0027] Open the regulating valves of all gas-phase feed pipelines to the first gas-phase opening at the first gas-phase valve rate, then fully open the regulating valve of the first gas-phase feed pipeline at the second gas-phase valve rate, purge for the second set purge time, after the purging is completed, close the regulating valve of the first gas-phase feed pipeline to the first gas-phase opening at the third gas-phase valve rate, and at the same time fully open the regulating valve of the second gas-phase feed pipeline at the second gas-phase valve rate, purge for the second set purge time until all gas-phase feed pipelines are purged; after all gas-phase feed pipelines are purged and it is confirmed that the convection section process is changed to liquid phase, control the regulating valves of all gas-phase feed pipelines to close at the first gas-phase valve rate.

[0028] Preferably, the rate of the first liquid-phase valve is 0-6% / min, the rate of the second liquid-phase valve is 6-12% / min, the rate of the third liquid-phase valve is 12-25% / min, the first opening degree of the liquid phase is 2-15%, the rate of the first gas-phase valve is 0-10% / min, the rate of the second gas-phase valve is 15-30% / min, the rate of the third gas-phase valve is 15-30% / min, the first opening degree of the gas phase is 2-15%, the first set purge time is 10-30 min, and the second set purge time is 5-20 min.

[0029] Preferably, the system further includes an operation navigation function module for providing operation prompts according to the control instructions of the intelligent control module for the purge process of the feed pipeline during the purge stage of the feed pipeline.

[0030] Preferably, when the damper opening degree reaches 8-12% or 80-95%, the operation navigation function module prompts to check whether the on-site damper opening degree is consistent with the central control damper opening degree, and check whether all the viewing holes and ignition holes are tightly closed.

[0031] Preferably, when the opening degree of the regulating valve of a single liquid-phase feed pipeline of the liquid-phase feed equipment and / or a single gas-phase feed pipeline of the gas-phase feed equipment reaches 100%, the operation navigation function module prompts to cut out the feed flowmeter and continue purging through the bypass.

[0032] Preferably, the system further includes a process key parameter monitoring and alarm module for monitoring the process key parameters during the purge stage of the feed pipeline and giving an alarm when the process key parameters exceed the preset range.

[0033] Preferably, the process key parameters include the cracking furnace outlet temperature, fuel gas calorific value, fuel gas pressure, furnace oxygen content, cracking furnace damper opening degree, cross-section pressure, CO content in the cracked gas, VHS steam drum liquid level, ultra-high pressure steam temperature, and ultra-high pressure steam pressure.

[0034] Preferably, the monitoring of the process key parameters and the alarm when the process key parameters exceed the preset range specifically include:

[0035] Giving an alarm when the process key parameters exceed the first preset range;

[0036] When the process key parameters exceed the second preset range, adjusting the process key parameters exceeding the second preset range to within the first preset range at a preset ratio based on their current values and giving an alarm.

[0037] Preferably, the upper limit value of the second preset range is greater than the upper limit value of the first preset range, the lower limit value of the second preset range is less than the lower limit value of the first preset range, and the preset ratio is ±0.1 to 10%.

[0038] Preferably, the system further includes a purge process alarm optimization management module, which is used to automatically shield the purge instrument alarm and turn the purge instrument alarm activation indicator light red during the purge stage of the feed pipeline. When the purge is completed, the purge instrument alarm is activated and the purge instrument alarm activation indicator light is turned green.

[0039] Preferably, the types of the purge instrument alarms include total feed alarm, liquid feed flow alarm of the cracking furnace, gas feed flow alarm of the cracking furnace, feed interlock pressure alarm, DMDS pressure alarm, DMDS flow alarm, anti-coking steam pressure difference alarm, quench oil flow alarm, Venturi inlet pressure alarm, cracking gas analysis indication alarm, low liquid raw material flow alarm of the furnace tube, and low gas raw material pressure alarm.

[0040] Preferably, the system further includes a deep learning function module, which is used to learn the control quality of the key parameters of the purge process based on empirical values and big data during the purge stage of the feed pipeline, and derive the optimal control values of the key parameters of the purge process.

[0041] In order to achieve the above object, the second aspect of the present invention provides an automatic execution method for purging the feed pipeline of an ethylene cracking furnace. This method is implemented using the above system, and the method includes:

[0042] Using a pre-purge status confirmation module to confirm the initial parameters and the initial status of the cracking furnace before purging, and when the initial parameters are within the initial range and the initial status of the cracking furnace meets the purging conditions, indicating that the feed pipeline can be purged. When the initial parameters are not within the initial range and / or the initial status of the cracking furnace does not meet the purging conditions, an alarm is issued;

[0043] Using an intelligent control module for the feed pipeline purge process to control the key parameters of the purge process, as well as the gas feed equipment and the liquid feed equipment during the purge stage of the feed pipeline, and issuing control instructions, wherein the key parameters of the purge process include the cracking furnace outlet temperature and the furnace chamber oxygen content;

[0044] Using a purge execution module to perform purging according to the control instructions of the intelligent control module for the feed pipeline purge process during the purge stage of the feed pipeline.

[0045] According to the above technical solution, based on this system, during the actual application process, the initial parameters and the initial state of the cracking furnace are confirmed by the pre-purging status confirmation module before purging. Then, during the purging stage of the feed pipeline, the key parameters of the purging process, as well as the gas-phase feed equipment and the liquid-phase feed equipment, are controlled by the intelligent control module for the purging process of the feed pipeline, and finally, the purging is carried out by the purging execution module according to the control instruction. This can effectively improve the purging efficiency of the feed pipeline and the stability of the system during the purging process, and has the advantages of high purging efficiency, high stability, and high safety. Description of the Drawings

[0046] Figure 1 is a flowchart of an automatic execution system for purging the feed pipeline of an ethylene cracking furnace. Specific Embodiments

[0047] The following details the specific embodiments of the embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the embodiments of the present invention, and are not intended to limit the embodiments of the present invention.

[0048] The first aspect of the present invention provides an automatic execution system for purging the feed pipeline of an ethylene cracking furnace, as Figure 1 shown. The system includes:

[0049] A pre-purging status confirmation module, configured to confirm the initial parameters and the initial state of the cracking furnace before purging, and when the initial parameters are within the initial range and the initial state of the cracking furnace meets the purging conditions, indicate that the purging of the feed pipeline can be carried out, and when the initial parameters are not within the initial range and / or the initial state of the cracking furnace does not meet the purging conditions, give an alarm;

[0050] An intelligent control module for the purging process of the feed pipeline, configured to control the key parameters of the purging process, as well as the gas-phase feed equipment and the liquid-phase feed equipment, during the purging stage of the feed pipeline, and issue a control instruction, wherein the key parameters of the purging process include the cracking furnace outlet temperature and the furnace chamber oxygen content;

[0051] A purging execution module, configured to perform purging according to the control instruction of the intelligent control module for the purging process of the feed pipeline during the purging stage of the feed pipeline.

[0052] According to the above technical solution, based on this system, in the actual application process, before purging, the initial parameters and the initial state of the cracking furnace are confirmed by the pre-purging state confirmation module, and then during the purging stage of the feed pipeline, the key parameters of the purging process, as well as the gas-phase feed equipment and the liquid-phase feed equipment, are controlled by the intelligent control module for the feed pipeline purging process. Finally, the purging is carried out by the purging execution module according to the control instructions, which can effectively improve the purging efficiency of the feed pipeline and the stability of the system during the purging process, and has the advantages of high purging efficiency, high stability and high safety.

[0053] In a preferred embodiment of the automatic execution system for purging the feed pipeline of the ethylene cracking furnace described in the present invention, when the initial parameters are not within the initial range, an alarm is given, specifically including:

[0054] When the initial parameters are not within the initial range, an alarm prompt is given for one or more of the initial parameters that are not within the initial range.

[0055] Among them, in a specific embodiment, the initial parameters include the cross-section pressure, the cracking furnace outlet temperature, the fuel gas pressure, and the dilution steam flow rate. Further, in a more specific embodiment, the initial range of the cross-section pressure is 0.10 - 0.35 MPa, the initial range of the cracking furnace outlet temperature is 720 - 750 °C, the initial range of the fuel gas pressure is 0.08 - 0.25 MPa, and the initial range of the dilution steam flow rate is 3500 - 4500 kg / h.

[0056] In the embodiment of the present invention, by ensuring that the relevant initial parameters are all within the set range before purging the feed pipeline, the accuracy and safety during the purging process of the feed pipeline can be effectively improved.

[0057] Furthermore, in another preferred embodiment, the initial state of the cracking furnace meets the purging conditions, specifically including:

[0058] The first feed root valve at the feed root of the cracking furnace has been closed, and the purging steam drainage and warm-up of the gas-phase feed equipment and the liquid-phase feed equipment are qualified. Thereby further improving the accuracy and safety during the purging process of the feed pipeline.

[0059] In a preferred embodiment of the automatic execution system for purging the feed pipeline of the ethylene cracking furnace described in the present invention, during the purging stage of the feed pipeline, the key parameters of the purging process are controlled and a control instruction is issued, specifically including:

[0060] Control the oxygen content in the furnace within the set oxygen content range. When the oxygen content in the furnace is lower than the lower limit value of the set oxygen content range, open the damper opening by the first damper amplitude. After the set time, if the oxygen content in the furnace is still lower than the lower limit value of the set oxygen content range, continue to open the damper opening by the first damper amplitude until the oxygen content in the furnace is within the set oxygen content range; when the oxygen content in the furnace is higher than the upper limit value of the set oxygen content range, close the damper opening by the second damper amplitude. After the set time, if the oxygen content in the furnace is still higher than the upper limit value of the set oxygen content range, continue to close the damper opening by the second damper amplitude until the oxygen content in the furnace is within the set oxygen content range;

[0061] Cascade control the outlet temperature of the cracking furnace and the calorific value of the fuel gas to control the outlet temperature of the cracking furnace within the set temperature range. When the outlet temperature of the cracking furnace is lower than the lower limit value of the set temperature range, the calorific value of the fuel gas rises at the first calorific value rate. After the set time, if the outlet temperature of the cracking furnace is still lower than the lower limit value of the set temperature range, the calorific value of the fuel gas continues to rise at the first calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; when the outlet temperature of the cracking furnace is lower than the first lower limit value, the calorific value of the fuel gas rises at the second calorific value rate. After the set time, if the outlet temperature of the cracking furnace is still lower than the first lower limit value, the calorific value of the fuel gas continues to rise at the second calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; wherein, the first lower limit value is less than the lower limit value of the set temperature range and the difference between the two is 2 - 10°C;

[0062] When the outlet temperature of the cracking furnace is higher than the upper limit value of the set temperature range, the calorific value of the fuel gas drops at the third calorific value rate. After the set time, if the outlet temperature of the cracking furnace is still higher than the upper limit value of the set temperature range, the calorific value of the fuel gas continues to drop at the third calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; when the outlet temperature of the cracking furnace is higher than the first upper limit value, the calorific value of the fuel gas drops at the fourth calorific value rate. After the set time, if the outlet temperature of the cracking furnace is still higher than the first upper limit value, the calorific value of the fuel gas continues to drop at the fourth calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; wherein, the first upper limit value is greater than the upper limit value of the set temperature range and the difference between the two is 2 - 10°C.

[0063] In a specific embodiment, the set oxygen content range is 0 - 10%, preferably 2 - 3.5%, the first damper amplitude and the second damper amplitude are 0.1 - 5%, the set temperature range is 710 - 760°C, the first calorific value rate, the second calorific value rate, the third calorific value rate and the fourth calorific value rate are 0 - 5 MW, and the set time is 0.1 - 5 min. Among them, preferably, the second calorific value rate is greater than the first calorific value rate, and the fourth calorific value rate is greater than the third calorific value rate.

[0064] In the embodiment of the present invention, by controlling the outlet temperature of the cracking furnace and the oxygen content in the furnace during the purging stage of the feed pipeline and stabilizing them within the set range, the problem that the outlet temperature of the cracking furnace and the oxygen content in the furnace fluctuate greatly due to manual purging based on experience, resulting in the unplanned shutdown of the ethylene plant, is effectively solved. At the same time, compared with manual purging, the purging efficiency and the stability and safety of the system during the purging process are greatly improved.

[0065] Further, in another preferred embodiment, during the purging stage of the feed pipeline, the gas-phase feed equipment and the liquid-phase feed equipment are controlled and control instructions are issued, which specifically include:

[0066] When the feed to the cracking furnace is liquid-phase feed, first purge the liquid-phase feed pipeline of the liquid-phase feed equipment, and then purge the gas-phase feed pipeline of the gas-phase feed equipment;

[0067] When the feed to the cracking furnace is gas-phase feed, first purge the gas-phase feed pipeline of the gas-phase feed equipment, and then purge the liquid-phase feed pipeline of the liquid-phase feed equipment.

[0068] In a specific embodiment, the purging of the liquid-phase feed pipeline of the liquid-phase feed equipment specifically includes:

[0069] Open the regulating valves of all liquid-phase feed pipelines to the first liquid opening at the first liquid valve rate, then fully open the regulating valve of the first liquid-phase feed pipeline at the second liquid valve rate, purge for the first set purge time, after the purging is completed, close the regulating valve of the first liquid-phase feed pipeline to the first liquid opening at the third liquid valve rate, and at the same time fully open the regulating valve of the second liquid-phase feed pipeline at the second liquid valve rate, purge for the first set purge time until all liquid-phase feed pipelines are purged; after all liquid-phase feed pipelines are purged and it is confirmed that the convection section process is changed to gas phase, control the regulating valves of all liquid-phase feed pipelines to close at the first liquid valve rate.

[0070] The purging of the gas-phase feed pipeline of the gas-phase feed equipment specifically includes:

[0071] Open the control valves of all gas-phase feed pipelines to the first gas-phase opening degree at the first gas-phase valve rate, then fully open the control valve of the first gas-phase feed pipeline at the second gas-phase valve rate, purge for the second set purge time. After the purge is completed, close the control valve of the first gas-phase feed pipeline to the first gas-phase opening degree at the third gas-phase valve rate. At the same time, fully open the control valve of the second gas-phase feed pipeline at the second gas-phase valve rate and purge for the second set purge time until all gas-phase feed pipelines are purged. After all gas-phase feed pipelines are purged and it is confirmed that the convection section process has been changed to the liquid phase, control the control valves of all gas-phase feed pipelines to close at the first gas-phase valve rate.

[0072] In a more specific embodiment, the first liquid-phase valve rate is 0-6% / min, the second liquid-phase valve rate is 6-12% / min, the third liquid-phase valve rate is 12-25% / min, the first liquid-phase opening degree is 2-15%, the first gas-phase valve rate is 0-10% / min, the second gas-phase valve rate is 15-30% / min, the third gas-phase valve rate is 15-30% / min, the first gas-phase opening degree is 2-15%, the first set purge time is 10-30 min, and the second set purge time is 5-20 min.

[0073] In the embodiment of the present invention, by controlling the outlet temperature of the cracking furnace and the oxygen content in the furnace, as well as the gas-phase feed pipeline and the liquid-phase feed pipeline simultaneously during the purge stage of the feed pipeline, not only the purge efficiency during the purge process of the feed pipeline is greatly improved, but also the stability and safety of the system are greatly improved, thereby effectively improving the overall efficiency of ethylene production in the ethylene plant.

[0074] Furthermore, in the present invention, due to the generally complex structure and large volume of the existing ethylene cracking furnace, the commissioning of some devices cannot be directly controlled by the intelligent control module for the purge process of the feed pipeline or the control by the intelligent control module for the purge process of the feed pipeline is rather inefficient and costly. Therefore, based on the above specific embodiment in the present invention, although the stability, safety and purge efficiency are greatly improved compared with manual purge according to experience, the optimal purge effect of the feed pipeline still cannot be achieved. Based on this, an operation navigation function module is further set in the present invention, so as to further effectively ensure the stability, safety and efficiency of the purge process of the feed pipeline based on the combination of automatic control and manual operation. Among them, the operations performed by the operation navigation function module are all based on the relevant devices of the existing ethylene cracking furnace, and the operation objects will not be described here.

[0075] That is, for the automatic execution system for purging the feed pipeline of the ethylene cracking furnace described in the present invention, in a preferred embodiment, the system further includes an operation navigation function module, which is used to give operation prompts according to the control instructions of the intelligent control module for the purging process of the feed pipeline during the purging stage of the feed pipeline.

[0076] In a specific embodiment, when the damper opening reaches 8-12% or 80-95%, preferably, when the damper opening reaches 10% or 90%, the operation navigation function module prompts to check whether the on-site damper opening is consistent with the central control damper opening, and check whether all the viewing holes and ignition holes are tightly closed.

[0077] In another specific embodiment, when the regulating valve opening of a single liquid-phase feed pipeline of the liquid-phase feed equipment and / or a single gas-phase feed pipeline of the gas-phase feed equipment reaches 100%, the operation navigation function module prompts to cut out the feed flowmeter and continue purging by changing to the bypass.

[0078] In another specific embodiment, when the furnace inlet of the cracking furnace is liquid-phase feed, first purge the liquid-phase feed pipeline of the liquid-phase feed equipment, and then purge the gas-phase feed pipeline of the gas-phase feed equipment. Specifically, it further includes: when purging the liquid-phase feed pipeline, the operation navigation function module prompts to open the liquid-phase feed root valve and then discharge the HBD process, purge the liquid-phase feed hand valve to the blind pipe section at the purge steam inlet for 5-10 minutes, and after the purging of the liquid-phase feed pipeline is completed, prompt to change the convection section process to gas phase and close the hand valve at the DS injection point for liquid-phase purging; when purging the gas-phase feed pipeline, the operation navigation function module prompts to fully open the torch valve, open the gas-phase feed root valve and then discharge the WF process, purge the gas-phase feed hand valve to the blind pipe section at the purge steam inlet for 3-5 minutes.

[0079] In another specific embodiment, when the furnace inlet of the cracking furnace is gas-phase feed, first purge the gas-phase feed pipeline of the gas-phase feed equipment, and then purge the liquid-phase feed pipeline of the liquid-phase feed equipment. Specifically, it further includes: when purging the gas-phase feed pipeline, the operation navigation function module prompts to fully open the torch valve, open the gas-phase feed root valve and then discharge the WF process, purge the gas-phase feed hand valve to the blind pipe section at the purge steam inlet for 3-5 minutes, and after the purging of the gas-phase feed pipeline is completed, prompt to change the convection section process to liquid phase and close the hand valve at the DS injection point for gas-phase purging; when purging the liquid-phase feed pipeline, the operation navigation function module prompts to open the liquid-phase feed root valve and then discharge the HBD process, purge the liquid-phase feed hand valve to the blind pipe section at the purge steam inlet for 5-10 minutes.

[0080] In the embodiments of the present invention, the purging process of the feed pipeline is directly controlled by the intelligent control module of the feed pipeline purging process, and indirectly controlled by the intelligent control module of the feed pipeline purging process prompting the operator to operate through the operation navigation function module, effectively improving the efficiency, stability, safety and economy of the feed pipeline purging process.

[0081] In a preferred embodiment of the automatic execution system for purging the feed pipeline of the ethylene cracking furnace of the present invention, the system further includes a process key parameter monitoring and alarm module, which is used to monitor the process key parameters during the purging stage of the feed pipeline, and alarm when the process key parameters exceed the preset range.

[0082] In a specific embodiment, the process key parameters include the cracking furnace outlet temperature, fuel gas calorific value, fuel gas pressure, furnace oxygen content, cracking furnace damper opening, cross-section pressure, CO content in the cracked gas, VHS steam drum liquid level, ultra-high pressure steam temperature and ultra-high pressure steam pressure.

[0083] In another specific embodiment, the monitoring of the process key parameters and the alarm when the process key parameters exceed the preset range specifically include:

[0084] Alarm when the process key parameters exceed the first preset range;

[0085] When the process key parameters exceed the second preset range, adjust the process key parameters exceeding the second preset range to within the first preset range at a preset ratio based on their current values, and alarm.

[0086] The upper limit value of the second preset range is greater than the upper limit value of the first preset range, the lower limit value of the second preset range is less than the lower limit value of the first preset range, and the preset ratio is ±0.1 to 10%.

[0087] In the embodiment of the present invention, taking the oxygen content in the furnace of the process key parameters as an example, the first preset range is 2 - 3.5%, and the second preset range is 1 - 10%. When the process key parameter monitoring and alarm module monitors that the oxygen content in the furnace is 1.4%, an alarm is issued; when the process key parameter monitoring and alarm module monitors that the oxygen content in the furnace is 0.8%, on the basis of 0.8%, the oxygen content in the furnace is increased to the first preset range at a ratio of 0.1% - 10%, thereby improving the safety and stability of the system during the entire feed purging process. Further, the process key parameter monitoring and alarm module can set the alarm display status according to the priority, and the alarm sound and light signals should be easily distinguishable. For example, when the oxygen content in the furnace exceeds the first preset range, a first-level alarm is adopted; when the oxygen content in the furnace exceeds the second preset range, a second-level alarm is issued. Specifically, the first-level alarm uses yellow background with black characters, flashing, and low-frequency sound, and the second-level alarm uses orange background with black characters, flashing, and medium-frequency sound. Moreover, the boundary values of the first preset range and the second preset range should not coincide with the instrument range of the alarm device of the process key parameter monitoring and alarm module, and should be set within the range of 10% - 90% of the maximum instrument range. Furthermore, if the oxygen content in the furnace cannot be maintained within the preset range through automatic adjustment, the purging is stopped. After the operator eliminates the fault, the purging is continued, thereby further ensuring the safety of the system operation.

[0088] In a preferred embodiment of the ethylene cracking furnace feed pipeline purging automatic execution system of the present invention, the system further includes a purging process alarm optimization management module, which is used to automatically shield the purging instrument alarm and turn the purging instrument alarm activation indicator light red during the feed pipeline purging stage. When the purging is completed, the purging instrument alarm is activated, and the purging instrument alarm activation indicator light turns green.

[0089] In a specific embodiment, the types of the purging instrument alarms include total feed alarm, liquid feed flow alarm of the cracking furnace, gas feed flow alarm of the cracking furnace, feed interlock pressure alarm, DMDS pressure alarm, DMDS flow alarm, anti-coking steam pressure difference alarm, quench oil flow alarm, Venturi inlet pressure alarm, cracking gas analysis indication alarm, low furnace tube liquid raw material flow alarm, and low gas raw material pressure alarm.

[0090] In the embodiment of the present invention, by further shielding invalid alarms during the feed pipeline purging stage, the efficiency of the feed pipeline purging can be further effectively improved, thereby increasing the output of the entire ethylene production plant.

[0091] In a preferred embodiment of the automatic execution system for purging the feed pipeline of the ethylene cracking furnace according to the present invention, the system further includes a deep learning function module, which is used to learn the control quality of the key parameters of the purging process based on empirical values and big data during the purging stage of the feed pipeline, and derive the optimal control values of the key parameters of the purging process, so as to ensure the stability of the purging process of the feed pipeline to the greatest extent and improve the purging efficiency.

[0092] In a preferred embodiment of the automatic execution system for purging the feed pipeline of the ethylene cracking furnace according to the present invention, the system further includes an inspection module after purging the feed pipeline, which is used to conduct a systematic inspection of the cracking furnace after the purging of the feed pipeline is completed to ensure that the cracking furnace is in a normal state after the purging of the feed pipeline is completed.

[0093] In a specific embodiment of the automatic execution system for purging the feed pipeline of the ethylene cracking furnace according to the present invention, the system is composed of a human-machine interaction interface and a program control system, so as to realize online control through a combined method based on the configuration of the field distributed control system (DCS) and the programming of the host computer server. At the same time, in order to realize the automatic execution of the purging process of the feed pipeline of the ethylene cracking furnace, an independent server needs to be deployed on the industrial control network. The execution program of the purging process of the feed pipeline of the ethylene cracking furnace performs data interaction through the OPC DA interface of the OPC server of Emerson DCS to obtain the numerical values or states of relevant parameters. In order to ensure the safe operation of the DCS system, an industrial firewall is added between the system server and the communication interface. By configuring corresponding rule policies, deep isolation and protection of the DCS control system are realized, the virus transmission path is cut off, and the normal, safe and stable operation of the DCS production control system of the device is ensured. The industrial firewall incorporates private communication protocols of multiple mainstream automation product manufacturers, and can realize seamless access to various mainstream automation products such as Honeywell DCS, Yokogawa DCS, Emerson DCS systems, as well as servers or databases such as OPC SERVER, IP21 / PHD / PI.

[0094] Among them, the interface design of the human-machine interaction interface has function buttons such as "Settings" for parameters, "Confirmation" of the cracking furnace status, "Run" the program, "Pause" during operation, "Resume" during operation, "Stop" during operation, and "Alarm" for parameters to implement human-machine interaction functions. Specifically, during use, clicking the "Parameter Settings" button allows manual setting of the control thresholds of the key parameters of the program and the preset upper and lower limits of the key parameters according to the working conditions; clicking the "Cracking Furnace Status Confirmation" button completes the status confirmation work before the purge of the feed pipeline, and the interface jumps to the purge operation interface of the feed pipeline. Otherwise, the purge program of the feed pipeline cannot run; clicking the "Program Run" button starts the purge program of the feed pipeline; clicking "Pause", the system stops the next step of the program, and the control values of each parameter of the purge program of the feed pipeline remain the current values. Clicking "Resume", the program will continue according to the current execution steps; manually clicking "Stop", the system stops the purge program of the cracking furnace feed pipeline and switches to manual operation; clicking the "Alarm Button", the human-machine interaction interface switches to the alarm interface, where the system alarm situation can be viewed in detail, and at the same time, the key parameter alarm shielding function during the purge process of the feed pipeline can be selected according to needs.

[0095] Furthermore, the functions of the human-machine interaction interface also include system operation status display, system operation buttons, key parameter trend charts, and system alarm prompt information. Among them, for the function buttons such as "Run", "Stop", "Pause", "Resume", and "Parameter Settings" designed on the human-machine interaction interface, during the operation of the system, users can execute the above function buttons at any time according to the actual operation of the ethylene plant.

[0096] The second aspect of the present invention also provides an automatic execution method for purging the feed pipeline of an ethylene cracking furnace. This method is implemented using the described system, and this method includes:

[0097] Using a pre-purge status confirmation module to confirm the initial parameters and the initial status of the cracking furnace before purging, and when the initial parameters are within the initial range and the initial status of the cracking furnace meets the purging conditions, indicating that the feed pipeline can be purged. When the initial parameters are not within the initial range and / or the initial status of the cracking furnace does not meet the purging conditions, an alarm is issued;

[0098] Using an intelligent control module for the feed pipeline purge process to control the key parameters during the purge process, as well as the gas-phase feed equipment and liquid-phase feed equipment, and issuing control instructions. Among them, the key parameters during the purge process include the cracking furnace outlet temperature and the furnace chamber oxygen content;

[0099] Using a purge execution module to perform purging according to the control instructions of the intelligent control module for the feed pipeline purge process during the feed pipeline purge stage.

[0100] According to the method of the present invention, in the actual application process, before purging, the initial parameters and the initial state of the cracking furnace are confirmed by the pre-purging state confirmation module, and then during the purging stage of the feed pipeline, the key parameters of the purging process, as well as the gas-phase feed equipment and the liquid-phase feed equipment, are controlled by the intelligent control module for the feed pipeline purging process. Finally, the purging execution module performs purging according to the control instruction, which can effectively improve the purging efficiency of the feed pipeline and the stability of the system during the purging process, and has the advantages of high purging efficiency, high stability and high safety.

[0101] The present invention will be described in detail below through embodiments, but the protection scope of the present invention is not limited thereto.

[0102] Embodiment 1

[0103] Based on an ethylene cracking furnace with a production capacity of 140,000 tons / year, the automatic execution system for purging the feed pipeline of the ethylene cracking furnace as shown in the present invention is implemented. Specifically, the automatic execution system for purging the feed pipeline of the ethylene cracking furnace includes: Figure 1 A pre-purging state confirmation module, which is used to confirm the initial parameters and the initial state of the cracking furnace before purging, and when the initial parameters are within the initial range and the initial state of the cracking furnace meets the purging conditions, it indicates that the feed pipeline can be purged. When the initial parameters are not within the initial range and / or the initial state of the cracking furnace does not meet the purging conditions, an alarm is given;

[0104] An intelligent control module for the feed pipeline purging process, which is used to control the key parameters of the purging process, as well as the gas-phase feed equipment and the liquid-phase feed equipment during the purging stage of the feed pipeline, and issue a control instruction. Among them, the key parameters of the purging process include the cracking furnace outlet temperature and the furnace oxygen content;

[0105] A purging execution module, which is used to perform purging according to the control instruction of the intelligent control module for the feed pipeline purging process during the purging stage of the feed pipeline.

[0106] Specifically, when the initial parameters are not within the initial range, giving an alarm specifically includes:

[0107] When the initial parameters are not within the initial range, an alarm prompt is given for one or more of the initial parameters that are not within the initial range.

[0108]

[0109] ​The initial parameters include the cross-section pressure, the cracking furnace outlet temperature, the fuel gas pressure, and the dilution steam flow rate. The initial range of the cross-section pressure is 0.10 - 0.35 MPa, the initial range of the cracking furnace outlet temperature is 720 - 750 °C, the initial range of the fuel gas pressure is 0.08 - 0.25 MPa, and the initial range of the dilution steam flow rate is 3500 - 4500 kg / h.

[0110] The initial state of the cracking furnace reaches the purging condition, specifically including:

[0111] The first feed root valve at the feed root of the cracking furnace has been closed, and the purging steam condensate drainage and pipe warming of the gas-phase feed equipment and the liquid-phase feed equipment are qualified.

[0112] In the actual application process, first, the pre-purging state confirmation module confirms the initial parameters and the initial state of the cracking furnace before purging. After confirming that purging can be carried out, the intelligent control module for the feed pipeline purging process controls the key parameters of the purging process, as well as the gas-phase feed equipment and the liquid-phase feed equipment, during the feed pipeline purging stage, and the purging execution module performs purging according to the control instructions.

[0113] After testing, using the system of the present invention can effectively improve the purging efficiency of the feed pipeline and the stability of the system during the purging process, and has the advantages of high purging efficiency, high stability, and high safety.

[0114] Example 2

[0115] Implemented with reference to Example 1, the difference is that during the feed pipeline purging stage, the key parameters of the purging process are controlled and control instructions are issued, specifically including:

[0116] Control the oxygen content in the furnace within the set oxygen content range. When the oxygen content in the furnace is lower than the lower limit value of the set oxygen content range, open the damper opening with the first damper amplitude. If the oxygen content in the furnace is still lower than the lower limit value of the set oxygen content range after the set time, continue to open the damper opening with the first damper amplitude until the oxygen content in the furnace is within the set oxygen content range; when the oxygen content in the furnace is higher than the upper limit value of the set oxygen content range, close the damper opening with the second damper amplitude. If the oxygen content in the furnace is still higher than the upper limit value of the set oxygen content range after the set time, continue to close the damper opening with the second damper amplitude until the oxygen content in the furnace is within the set oxygen content range;

[0117] Cascade control of the outlet temperature of the cracking furnace and the calorific value of the fuel gas to control the outlet temperature of the cracking furnace within the set temperature range. When the outlet temperature of the cracking furnace is lower than the lower limit value of the set temperature range, the calorific value of the fuel gas rises at the first calorific value rate. If the outlet temperature of the cracking furnace is still lower than the lower limit value of the set temperature range after the set time, the calorific value of the fuel gas continues to rise at the first calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; when the outlet temperature of the cracking furnace is lower than the first lower limit value, the calorific value of the fuel gas rises at the second calorific value rate. If the outlet temperature of the cracking furnace is still lower than the first lower limit value after the set time, the calorific value of the fuel gas continues to rise at the second calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; wherein, the first lower limit value is less than the lower limit value of the set temperature range and the difference between the two is 5°C;

[0118] When the outlet temperature of the cracking furnace is higher than the upper limit value of the set temperature range, the calorific value of the fuel gas drops at the third calorific value rate. If the outlet temperature of the cracking furnace is still higher than the upper limit value of the set temperature range after the set time, the calorific value of the fuel gas continues to drop at the third calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; when the outlet temperature of the cracking furnace is higher than the first upper limit value, the calorific value of the fuel gas drops at the fourth calorific value rate. If the outlet temperature of the cracking furnace is still higher than the first upper limit value after the set time, the calorific value of the fuel gas continues to drop at the fourth calorific value rate until the outlet temperature of the cracking furnace is within the set temperature range; wherein, the first upper limit value is greater than the upper limit value of the set temperature range and the difference between the two is 5°C.

[0119] The set oxygen content range is 0-10%, the first damper amplitude and the second damper amplitude are 0.1-5%, the set temperature range is 710-760°C, the first calorific value rate, the second calorific value rate, the third calorific value rate and the fourth calorific value rate are 0-5 MW, and the set time is 0.1-5 min.

[0120] Specifically, the set oxygen content range is 2-3.5%, the first damper amplitude and the second damper amplitude are 2%, the set temperature range is 735-740°C, the first calorific value rate is 0.1 MW, the second calorific value rate is 0.2 MW, the third calorific value rate is 0.15 MW, the fourth calorific value rate is 0.3 MW, and the set time is 1 min.

[0121] In the actual application process, first, the pre-purging status confirmation module confirms the initial parameters and the initial status of the cracking furnace before purging. After confirming that purging can be carried out, the intelligent control module for the feeding pipeline purging process controls the key parameters of the purging process, as well as the gas-phase feeding equipment and the liquid-phase feeding equipment during the feeding pipeline purging stage, and the purging execution module performs purging according to the control instructions; among them, the specific process of the intelligent control module for the feeding pipeline purging process controlling the key parameters of the purging process is as described above.

[0122] After testing, by using the system of the present invention, compared with the solution in Embodiment 1, the purging efficiency of the feeding pipeline and the stability of the system during the purging process can be further effectively improved, and it has the advantages of higher purging efficiency, higher stability and higher safety.

[0123] Embodiment 3

[0124] Implemented with reference to Embodiment 2, the difference is that during the feeding pipeline purging stage, controlling the gas-phase feeding equipment and the liquid-phase feeding equipment and issuing control instructions specifically includes:

[0125] When the feed to the cracking furnace hearth is liquid-phase feed, first purge the liquid-phase feed pipeline of the liquid-phase feeding equipment, and then purge the gas-phase feed pipeline of the gas-phase feeding equipment;

[0126] When the feed to the cracking furnace hearth is gas-phase feed, first purge the gas-phase feed pipeline of the gas-phase feeding equipment, and then purge the liquid-phase feed pipeline of the liquid-phase feeding equipment.

[0127] The purging of the liquid-phase feed pipeline of the liquid-phase feeding equipment specifically includes:

[0128] Open the regulating valves of all liquid-phase feed pipelines to the first liquid-phase opening at the first liquid-phase valve rate, then fully open the regulating valve of the first liquid-phase feed pipeline at the second liquid-phase valve rate, purge for the first set purge time, after the purging is completed, close the regulating valve of the first liquid-phase feed pipeline to the first liquid-phase opening at the third liquid-phase valve rate, and at the same time fully open the regulating valve of the second liquid-phase feed pipeline at the second liquid-phase valve rate, purge for the first set purge time until all liquid-phase feed pipelines are purged; after all liquid-phase feed pipelines are purged and it is confirmed that the convection section process has changed to gas phase, control the regulating valves of all liquid-phase feed pipelines to close at the first liquid-phase valve rate.

[0129] The purging of the gas-phase feed pipeline of the gas-phase feeding equipment specifically includes:

[0130] Open the control valves of all gas-phase feed pipelines to the first gas-phase opening at the first gas-phase valve rate, then fully open the control valve of the first gas-phase feed pipeline at the second gas-phase valve rate, purge for the second set purge time. After the purge is completed, close the control valve of the first gas-phase feed pipeline to the first gas-phase opening at the third gas-phase valve rate. At the same time, fully open the control valve of the second gas-phase feed pipeline at the second gas-phase valve rate and purge for the second set purge time until all gas-phase feed pipelines are purged; after all gas-phase feed pipelines are purged and it is confirmed that the convection section process has been changed to the liquid phase, control the control valves of all gas-phase feed pipelines to close at the first gas-phase valve rate.

[0131] The first liquid-phase valve rate is 0-6% / min, the second liquid-phase valve rate is 6-12% / min, the third liquid-phase valve rate is 12-25% / min, the first liquid-phase opening is 2-15%, the first gas-phase valve rate is 0-10% / min, the second gas-phase valve rate is 15-30% / min, the third gas-phase valve rate is 15-30% / min, the first gas-phase opening is 2-15%, the first set purge time is 10-30 min, and the second set purge time is 5-20 min.

[0132] Specifically, the first liquid-phase valve rate is 5% / min, the second liquid-phase valve rate is 10% / min, the third liquid-phase valve rate is 15% / min, the first liquid-phase opening is 5%, the first gas-phase valve rate is 5% / min, the second gas-phase valve rate is 20% / min, the third gas-phase valve rate is 20% / min, the first gas-phase opening is 5%, the first set purge time is 15 min, and the second set purge time is 10 min.

[0133] In the actual application process, first, the pre-purge status confirmation module confirms the initial parameters and the initial status of the cracking furnace before purging. After confirming that purging can be carried out, the intelligent control module for the feed pipeline purging process controls the key parameters of the purging process, as well as the gas-phase feed equipment and the liquid-phase feed equipment during the feed pipeline purging stage, and the purge execution module performs purging according to the control instructions; among them, the specific process of the intelligent control module for the feed pipeline purging process controlling the key parameters of the purging process, as well as the gas-phase feed equipment and the liquid-phase feed equipment during the feed pipeline purging stage is as described above.

[0134] After testing, using the system of the present invention, compared with the solution in Embodiment 2, it can further effectively improve the purging efficiency of the feed pipeline and the stability of the system during the purging process, and has the advantages of higher purging efficiency, higher stability, and higher safety.

[0135] Example 4

[0136] Implemented with reference to Embodiment 3, except that the system further includes an operation navigation function module, which is used to give operation prompts according to the control instructions of the intelligent control module for the purging process of the feed pipeline during the purging stage of the feed pipeline. When the damper opening reaches 8-12% or 80-95%, the operation navigation function module prompts to check whether the on-site damper opening is consistent with the central control damper opening, and check whether all the sight holes and ignition holes are tightly closed. When the regulating valve opening of a single liquid-phase feed pipeline of the liquid-phase feed equipment and / or a single gas-phase feed pipeline of the gas-phase feed equipment reaches 100%, the operation navigation function module prompts to cut out the feed flowmeter and switch to the bypass for continuous purging.

[0137] It is detected that by using the system of the present invention, compared with the solution in Embodiment 3, the purging efficiency of the feed pipeline can be further effectively improved.

[0138] Embodiment 5

[0139] Implemented with reference to Embodiment 4, except that the system further includes a process key parameter monitoring and alarm module, which is used to monitor the process key parameters during the purging stage of the feed pipeline and give an alarm when the process key parameters exceed the preset range. The process key parameters include the cracking furnace outlet temperature, fuel gas calorific value, fuel gas pressure, furnace oxygen content, cracking furnace damper opening, cross-section pressure, CO content in the cracked gas, VHS steam drum level, ultra-high pressure steam temperature, and ultra-high pressure steam pressure.

[0140] It is detected that by using the system of the present invention, compared with the solution in Embodiment 4, the stability and safety of the system during the purging process of the feed pipeline can be further effectively improved.

[0141] Embodiment 6

[0142] Implemented with reference to Embodiment 5, except that monitoring the process key parameters and giving an alarm when the process key parameters exceed the preset range specifically includes:

[0143] Giving an alarm when the process key parameters exceed the first preset range;

[0144] When the process key parameters exceed the second preset range, the process key parameters exceeding the second preset range are adjusted to within the first preset range at a preset ratio based on their current values, and an alarm is given. The upper limit value of the second preset range is greater than the upper limit value of the first preset range, the lower limit value of the second preset range is less than the lower limit value of the first preset range, and the preset ratio is ±0.1-10%.

[0145] After testing, using the system described in the present invention, compared with the solution in Example 5, the stability and safety of the system during the purging process of the feed pipeline can be further effectively improved.

[0146] Example 7

[0147] Implemented with reference to Example 6. The difference is that the system further includes a purging process alarm optimization management module, which is used to automatically shield the purging instrument alarm and turn the enabling indicator light of the purging instrument alarm red during the purging stage of the feed pipeline. When the purging is completed, the purging instrument alarm is enabled and the enabling indicator light of the purging instrument alarm is turned green. The types of the purging instrument alarm include total feed amount alarm, liquid feed flow alarm of the cracking furnace, gas feed flow alarm of the cracking furnace, feed interlock pressure alarm, DMDS pressure alarm, DMDS flow alarm, anti-coking steam pressure difference alarm, quench oil flow alarm, Venturi inlet pressure alarm, cracking gas analysis indication alarm, low liquid raw material flow alarm in the furnace tube, and low gas raw material pressure alarm.

[0148] After testing, using the system described in the present invention, compared with the solution in Example 6, the purging efficiency of the feed pipeline can be further effectively improved.

[0149] Example 8

[0150] Implemented with reference to Example 7. The difference is that the system further includes a deep learning function module, which is used to learn the control quality of the key parameters of the purging process based on empirical values and big data during the purging stage of the feed pipeline, and derive the optimal control values of the key parameters of the purging process.

[0151] After testing, using the system described in the present invention, compared with the solution in Example 7, the purging efficiency of the feed pipeline and the stability and safety of the system during the purging process can be further effectively improved.

[0152] Example 9

[0153] Implemented with reference to Example 8, except that the set oxygen content range is 2 - 3.5%, the first damper amplitude and the second damper amplitude are 3%, the set temperature range is 735 - 740 °C, the first calorific value rate is 0.14 MW, the second calorific value rate is 0.25 MW, the third calorific value rate is 0.2 MW, the fourth calorific value rate is 0.35 MW, the set time is 2 min; the liquid-phase first valve rate is 4% / min, the liquid-phase second valve rate is 9% / min, the liquid-phase third valve rate is 14% / min, the liquid-phase first opening is 4%, the gas-phase first valve rate is 4% / min, the gas-phase second valve rate is 16% / min, the gas-phase third valve rate is 18% / min, the gas-phase first opening is 4%, the first set purge time is 12 min, and the second set purge time is 8 min.

[0154] It is detected that by using the system of the present invention, the purge efficiency of the feed pipeline and the stability of the system during the purge process can be effectively improved, and it has the advantages of higher purge efficiency, higher stability and higher safety.

[0155] Example 10

[0156] Implemented with reference to Example 8, except that the set oxygen content range is 2 - 3.5%, the first damper amplitude and the second damper amplitude are 3.5%, the set temperature range is 735 - 740 °C, the first calorific value rate is 0.5 MW, the second calorific value rate is 0.8 MW, the third calorific value rate is 0.6 MW, the fourth calorific value rate is 1.2 MW, the set time is 4 min; the liquid-phase first valve rate is 3% / min, the liquid-phase second valve rate is 8% / min, the liquid-phase third valve rate is 16% / min, the liquid-phase first opening is 6%, the gas-phase first valve rate is 3% / min, the gas-phase second valve rate is 14% / min, the gas-phase third valve rate is 18% / min, the gas-phase first opening is 6%, the first set purge time is 13 min, and the second set purge time is 9 min.

[0157] It is detected that by using the system of the present invention, the purge efficiency of the feed pipeline and the stability of the system during the purge process can be effectively improved, and it has the advantages of higher purge efficiency, higher stability and higher safety.

[0158] The automatic execution system and method for purging the feed pipeline of an ethylene cracking furnace provided by the present invention confirm the initial parameters and the initial state of the cracking furnace before purging through a pre-purging status confirmation module, then control the key parameters of the purging process, the gas-phase feed equipment and the liquid-phase feed equipment during the purging stage of the feed pipeline through a smart control module for the purging process of the feed pipeline, and finally perform purging according to the control instructions through a purging execution module, which can effectively improve the purging efficiency of the feed pipeline and the stability of the system during the purging process, and has the advantages of high purging efficiency, high stability and high safety.

[0159] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. To avoid unnecessary repetition, the present invention will not separately describe various possible combinations. But these simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. An automatic execution system for purging the feed pipeline of an ethylene cracking furnace, characterized in that, The system includes: A pre-purging status confirmation module, which is used to confirm the initial parameters and the initial status of the cracking furnace before purging, and when the initial parameters are within the initial range and the initial status of the cracking furnace meets the purging conditions, it indicates that the feed pipeline can be purged. When the initial parameters are not within the initial range and / or the initial status of the cracking furnace does not meet the purging conditions, an alarm is given; An intelligent control module for the feed pipeline purging process, which is used to control the key parameters of the purging process, as well as the gas-phase feed equipment and the liquid-phase feed equipment during the feed pipeline purging stage, and issue control instructions. Among them, the key parameters of the purging process include the cracking furnace outlet temperature and the furnace chamber oxygen content; A purging execution module, which is used to perform purging according to the control instructions of the intelligent control module for the feed pipeline purging process during the feed pipeline purging stage.

2. The system according to claim 1, wherein The alarm given when the initial parameters are not within the initial range specifically includes: When the initial parameters are not within the initial range, an alarm prompt is given for one or more of the initial parameters that are not within the initial range.

3. The system according to claim 1 or 2, characterized in that The initial parameters include the cross-section pressure, the cracking furnace outlet temperature, the fuel gas pressure, and the dilution steam flow rate.

4. The system according to claim 3, characterized in that The initial range of the cross-section pressure is 0.10 - 0.35 MPa, the initial range of the cracking furnace outlet temperature is 720 - 750 °C, the initial range of the fuel gas pressure is 0.08 - 0.25 MPa, and the initial range of the dilution steam flow rate is 3500 - 4500 kg / h.

5. The system according to claim 1, characterized in that The initial status of the cracking furnace meeting the purging conditions specifically includes: The first feed root valve at the feed root of the cracking furnace has been closed, and the purging steam condensate warming of the gas-phase feed equipment and the liquid-phase feed equipment is qualified.

6. The system according to claim 1, wherein The control of the key parameters of the purging process and the issuance of control instructions during the feed pipeline purging stage specifically includes: Controlling the furnace chamber oxygen content within the set oxygen content range. When the furnace chamber oxygen content is lower than the lower limit value of the set oxygen content range, the damper opening is increased by the first damper amplitude. If the furnace chamber oxygen content is still lower than the lower limit value of the set oxygen content range after a set time, the damper opening is continuously increased by the first damper amplitude until the furnace chamber oxygen content is within the set oxygen content range; when the furnace chamber oxygen content is higher than the upper limit value of the set oxygen content range, the damper opening is decreased by the second damper amplitude. If the furnace chamber oxygen content is still higher than the upper limit value of the set oxygen content range after a set time, the damper opening is continuously decreased by the second damper amplitude until the furnace chamber oxygen content is within the set oxygen content range; The cascade control of the cracking furnace outlet temperature and the calorific value of the fuel gas controls the cracking furnace outlet temperature within the set temperature range. When the cracking furnace outlet temperature is lower than the lower limit of the set temperature range, the calorific value of the fuel gas rises at the first calorific value rate. If the cracking furnace outlet temperature is still lower than the lower limit of the set temperature range after the set time, the calorific value of the fuel gas continues to rise at the first calorific value rate until the cracking furnace outlet temperature is within the set temperature range; when the cracking furnace outlet temperature is lower than the first lower limit, the calorific value of the fuel gas rises at the second calorific value rate. If the cracking furnace outlet temperature is still lower than the first lower limit after the set time, the calorific value of the fuel gas continues to rise at the second calorific value rate until the cracking furnace outlet temperature is within the set temperature range; wherein, the first lower limit is less than the lower limit of the set temperature range and the difference between the two is 2-10°C. When the cracking furnace outlet temperature is higher than the upper limit of the set temperature range, the calorific value of the fuel gas drops at the third calorific value rate. If the cracking furnace outlet temperature is still higher than the upper limit of the set temperature range after the set time, the calorific value of the fuel gas continues to drop at the third calorific value rate until the cracking furnace outlet temperature is within the set temperature range; when the cracking furnace outlet temperature is higher than the first upper limit, the calorific value of the fuel gas drops at the fourth calorific value rate. If the cracking furnace outlet temperature is still higher than the first upper limit after the set time, the calorific value of the fuel gas continues to drop at the fourth calorific value rate until the cracking furnace outlet temperature is within the set temperature range; wherein, the first upper limit is greater than the upper limit of the set temperature range and the difference between the two is 2-10°C.

7. The system according to claim 6, wherein The set oxygen content range is 0-10%, the first damper amplitude and the second damper amplitude are 0.1-5%, the set temperature range is 710-760°C, the first calorific value rate, the second calorific value rate, the third calorific value rate and the fourth calorific value rate are 0-5 MW, and the set time is 0.1-5 min.

8. The system according to claim 6, wherein During the purging stage of the feed pipeline, the gas-phase feed equipment and the liquid-phase feed equipment are controlled and control instructions are issued, specifically including: When the feed to the cracking furnace hearth is liquid-phase feed, first purge the liquid-phase feed pipeline of the liquid-phase feed equipment, and then purge the gas-phase feed pipeline of the gas-phase feed equipment. When the feed to the cracking furnace hearth is gas-phase feed, first purge the gas-phase feed pipeline of the gas-phase feed equipment, and then purge the liquid-phase feed pipeline of the liquid-phase feed equipment.

9. The system according to claim 8, wherein The purging of the liquid-phase feed pipeline of the liquid-phase feed equipment specifically includes: Open the control valves of all liquid-phase feed pipelines to the first liquid-phase opening degree at the first liquid-phase valve rate, then fully open the control valve of the first liquid-phase feed pipeline at the second liquid-phase valve rate, purge for the first set purge time. After the purge is completed, close the control valve of the first liquid-phase feed pipeline to the first liquid-phase opening degree at the third liquid-phase valve rate. At the same time, fully open the control valve of the second liquid-phase feed pipeline at the second liquid-phase valve rate and purge for the first set purge time until all liquid-phase feed pipelines are purged. After all liquid-phase feed pipelines are purged and it is confirmed that the convection section process has been changed to the gas phase, control the control valves of all liquid-phase feed pipelines to close at the first liquid-phase valve rate.

10. The system according to claim 8, wherein The purging of the gas-phase feed pipelines of the gas-phase feed equipment specifically includes: Open the control valves of all gas-phase feed pipelines to the first gas-phase opening degree at the first gas-phase valve rate, then fully open the control valve of the first gas-phase feed pipeline at the second gas-phase valve rate, purge for the second set purge time. After the purge is completed, close the control valve of the first gas-phase feed pipeline to the first gas-phase opening degree at the third gas-phase valve rate. At the same time, fully open the control valve of the second gas-phase feed pipeline at the second gas-phase valve rate and purge for the second set purge time until all gas-phase feed pipelines are purged. After all gas-phase feed pipelines are purged and it is confirmed that the convection section process has been changed to the liquid phase, control the control valves of all gas-phase feed pipelines to close at the first gas-phase valve rate.

11. The system according to claim 9 or 10, characterized in that, The first liquid-phase valve rate is 0 - 6% / min, the second liquid-phase valve rate is 6 - 12% / min, the third liquid-phase valve rate is 12 - 25% / min, the first liquid-phase opening degree is 2 - 15%, the first gas-phase valve rate is 0 - 10% / min, the second gas-phase valve rate is 15 - 30% / min, the third gas-phase valve rate is 15 - 30% / min, the first gas-phase opening degree is 2 - 15%, the first set purge time is 10 - 30 min, and the second set purge time is 5 - 20 min.

12. The system according to claim 8, wherein The system further includes an operation navigation function module for giving operation prompts according to the control instructions of the feed pipeline purging process intelligent control module during the feed pipeline purging stage.

13. The system according to claim 12, wherein When the damper opening degree reaches 8 - 12% or 80 - 95%, the operation navigation function module prompts to check whether the on-site damper opening degree is consistent with the central control damper opening degree and check whether all the viewing holes and ignition holes are tightly closed.

14. The system according to claim 12, wherein When the opening degree of the control valve of a single liquid-phase feed pipeline of the liquid-phase feed equipment and / or a single gas-phase feed pipeline of the gas-phase feed equipment reaches 100%, the operation navigation function module prompts to cut out the feed flowmeter and continue purging by changing to the bypass.

15. The system according to claim 1 or 6, characterized in that, The system further includes a process key parameter monitoring and alarm module for monitoring the process key parameters during the feed pipeline purging stage and giving an alarm when the process key parameters exceed the preset range.

16. The system according to claim 15, wherein The key process parameters include the cracking furnace outlet temperature, fuel gas calorific value, fuel gas pressure, furnace oxygen content, cracking furnace damper opening, cross-section pressure, CO content in the cracked gas, VHS steam drum liquid level, ultra-high pressure steam temperature, and ultra-high pressure steam pressure.

17. The system according to claim 15, wherein Monitoring the key process parameters and giving an alarm when the key process parameters exceed the preset range specifically includes: Giving an alarm when the key process parameters exceed the first preset range; When the key process parameters exceed the second preset range, adjusting the key process parameters exceeding the second preset range to within the first preset range at a preset ratio based on their current values, and giving an alarm.

18. The system according to claim 17, wherein The upper limit value of the second preset range is greater than the upper limit value of the first preset range, the lower limit value of the second preset range is less than the lower limit value of the first preset range, and the preset ratio is ±0.1 - 10%.

19. The system according to claim 1 or 6, characterized in that, The system further includes a purge process alarm optimization management module, which is used to automatically shield the purge instrument alarm during the feed pipeline purge stage and turn the purge instrument alarm activation indicator light red. When the purge is completed, the purge instrument alarm is activated and the purge instrument alarm activation indicator light is turned green.

20. The system according to claim 19, wherein The types of the purge instrument alarms include total feed alarm, cracking furnace liquid phase feed flow alarm, cracking furnace gas phase feed flow alarm, feed interlock pressure alarm, DMDS pressure alarm, DMDS flow alarm, anti-coking steam pressure difference alarm, quench oil flow alarm, Venturi inlet pressure alarm, cracked gas analysis indication alarm, furnace tube liquid raw material flow low alarm, and gas raw material pressure low alarm.

21. The system according to claim 1 or 6, characterized in that, The system further includes a deep learning function module, which is used to learn the control quality of the key purge process parameters based on empirical values and big data during the feed pipeline purge stage, and derive the optimal control values of the key purge process parameters.

22. An automatic execution method for purging the feed pipeline of an ethylene cracking furnace, characterized in that, The method is implemented using the system described in any one of claims 1 - 21 above. The method includes: Using a pre-purge status confirmation module to confirm the initial parameters and the initial state of the cracking furnace before the purge. When the initial parameters are within the initial range and the initial state of the cracking furnace meets the purge conditions, it indicates that the feed pipeline purge can be carried out. When the initial parameters are not within the initial range and / or the initial state of the cracking furnace does not meet the purge conditions, an alarm is given; Using a feed pipeline purge process intelligent control module to control the key purge process parameters, as well as the gas phase feed equipment and liquid phase feed equipment during the feed pipeline purge stage, and sending control instructions. Among them, the key purge process parameters include the cracking furnace outlet temperature and the furnace oxygen content; Using a purge execution module to perform the purge according to the control instructions of the feed pipeline purge process intelligent control module during the feed pipeline purge stage.

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