An ethylene cracking furnace material return process automatic execution system and method

Abstract

The present application relates to the technical field of petroleum chemical industry, in particular to an automatic execution system and method for the material returning process of an ethylene cracking furnace, which comprises a state confirmation module before material returning, used for confirming initial parameters before material returning, and when the initial parameters are within an initial range, indicating that material returning can be performed, and when the initial parameters are not within the initial range, giving an alarm; a material returning process control module, used for controlling key parameters of material returning in the material returning stage, and issuing a material returning instruction, wherein the key parameters of material returning include the material returning rate of a single pipe of a furnace chamber and the material returning rate of a total pipe of the furnace chamber; and a material returning module, used for receiving the material returning instruction and performing material returning. By using the system, the state before material returning is confirmed by the state confirmation module before material returning, and the key parameters of material returning in the material returning process are controlled by the material returning process control module, which can effectively improve the accuracy of material returning, and has the advantages of high material returning efficiency, high safety and small fluctuation.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, specifically to an automated system and method for the unloading process of an ethylene cracking furnace. Background Technology

[0002] Ethylene is a crucial basic raw material in the petrochemical industry and one of the petrochemical products with the largest demand and production volume. Its output, scale, and technological level signify the development level of a country's petrochemical industry. Tubular cracking furnaces, used for hydrocarbon cracking, are the core unit in ethylene production, determining the overall production capacity, stable operation, and total energy consumption of the entire ethylene plant. When hydrocarbons undergo steam cracking reactions in the radiant section of the tubular cracking furnace, secondary reactions such as polymerization and condensation occur, leading to coke accumulation on the inner wall of the furnace tubes, forming coke deposits. When coking causes the temperature of the outer wall of the radiant section furnace tubes, the outlet temperature of the quench boiler, or the pressure difference across the Venturi tubes to reach the production limit, it severely impacts ethylene production, causing a decrease in ethylene yield, increased energy consumption, shortened furnace tube life, and even affecting production safety.

[0003] Due to the coking characteristics of ethylene cracking furnaces, frequent and intermittent furnace unloading operations are necessary in practical applications. Currently, the unloading process in most domestic ethylene cracking furnaces is still manually controlled. Manual unloading requires frequent operation by technicians, is labor-intensive, and relies entirely on individual experience and operator responsibility, resulting in a high rate of error. Furthermore, due to varying operator experience, the unloading process is prone to temporary interruptions or repeated unloading operations. These interruptions or repeated unloading operations can cause significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow rate, potentially leading to unplanned shutdowns of the ethylene plant, affecting its long-term safe and stable operation, and causing a decrease in ethylene production.

[0004] Therefore, there is an urgent need for an automated system and method for the unloading process of an ethylene cracking furnace. Summary of the Invention

[0005] This invention addresses the problem in the prior art where manual unloading of ethylene cracking furnaces is used. Due to varying operator experience, this often results in temporary interruptions or repeated unloading operations. These interruptions or repeated unloading can lead to significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow rate, potentially causing unplanned shutdowns of the ethylene plant. The invention provides an automated system and method for the unloading process of ethylene cracking furnaces.

[0006] To achieve the above objectives, the first aspect of this invention provides an automatic execution system for the unloading process of an ethylene cracking furnace, the system comprising:

[0007] The pre-return status confirmation module is used to confirm the initial parameters before returning the material. When the initial parameters are within the initial range, it indicates that the material can be returned. When the initial parameters are not within the initial range, it issues an alarm.

[0008] The unloading process control module is used to control the key parameters of unloading during the unloading stage and issue unloading commands. The key parameters of unloading include the unloading rate of the single tube in the furnace and the unloading rate of the main tube in the furnace.

[0009] The material return module is used to receive material return instructions and perform material return.

[0010] Preferably, the step of issuing an alarm when the initial parameter is not within the initial range specifically includes:

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

[0012] Preferably, the initial parameters include the single-tube dilution steam flow rate in the furnace, the pyrolysis furnace outlet temperature, and the ultra-high pressure steam temperature.

[0013] Preferably, the initial range of the ultra-high pressure steam temperature is 515–525°C, the initial range of the pyrolysis furnace outlet temperature is 750–850°C, and the initial range of the single-tube dilution steam flow rate in the furnace is 2300–3000 kg / h.

[0014] Preferably, the material return stage includes a first material return stage, a second material return stage, and a third material return stage. In the first material return stage, material is returned to a first material return value through the furnace main pipe and stabilized at the first material return value for a preset time. In the second material return stage, material is returned to a second material return value through the furnace main pipe and stabilized at the second material return value for the preset time. In the third material return stage, all remaining material to be returned is returned through the furnace single pipe.

[0015] Preferably, during the unloading stage, controlling key parameters for unloading and issuing unloading instructions specifically includes:

[0016] In the first and second unloading stages, the unloading rate of the furnace main pipe is controlled so that the dilution steam flow rate of the furnace single pipe increases at a first preset rate and a second preset rate, respectively. In the third unloading stage, the unloading rate of the furnace single pipe is controlled, and when the unloading is completed, the dilution steam flow rate of the furnace single pipe is made to be 1.5 to 2.5 times its initial range.

[0017] Preferably, the first return value is 60-85% of the total amount of material to be returned, the second return value is 10-30% of the total amount of material to be returned, and the preset time is 0-20 minutes.

[0018] Preferably, in the first unloading stage and the second unloading stage, the unloading rate of the furnace main tube is 50-500 (kg / h) / min and 500-2000 (kg / h) / min, respectively. In the third unloading stage, the unloading rate of the furnace single tube is 15-125 (kg / h) / min, the first preset rate is 10-120 (kg / h) / min, and the second preset rate is 50-150 (kg / h) / min.

[0019] Preferably, the key parameters for material return also include the rate of decrease in the calorific value of the fuel gas, the fuel gas pressure, the oxygen content in the furnace, and the carbon monoxide content in the pyrolysis gas.

[0020] Preferably, the step of controlling key parameters for material return and issuing a material return command during the material return stage further includes:

[0021] During the material return process via the single furnace tube or the main furnace tube, the rate of decrease in the calorific value of the fuel gas is controlled at 0.5–2.0 MW / 1000 kg of material return, the fuel gas pressure is controlled at 0.06–0.22 MPa, the oxygen content in the furnace is controlled at 1.5–5%, and the carbon monoxide content in the pyrolysis gas is controlled at 0.05–0.07 mol%, so that the outlet temperature of the pyrolysis furnace is reduced to a set target temperature at a preset cooling rate based on its initial temperature, wherein the preset cooling rate is 0.3–2 °C / min, and the set target temperature is 720–750 °C.

[0022] Preferably, the system further includes a key parameter monitoring and alarm module for unloading materials, which is used to monitor the key parameters for unloading materials during the unloading stage and to issue an alarm when the key parameters for unloading materials exceed a preset range.

[0023] Preferably, the monitoring of the key parameters for material return, and the triggering of an alarm when the key parameters for material return exceed a preset range, specifically includes:

[0024] An alarm is triggered when the key parameters for material return exceed the first preset range;

[0025] When the material return key parameter exceeds the second preset range, the material return key parameter exceeding the second preset range will be adjusted to the first preset range according to a preset ratio based on its current value, and an alarm will be triggered.

[0026] Preferably, the upper limit of the second preset range is greater than the upper limit of the first preset range, the lower limit of the second preset range is less than the lower limit of the first preset range, and the preset ratio is ±0.1% to 10%.

[0027] Preferably, the system further includes an alarm optimization management module for the material return process, which automatically disables the material return instrument alarm and turns the material return instrument alarm activation indicator light red when the total amount of material returned is less than 40-65% of the design load of the material return equipment of the material return module; and activates the material return instrument alarm and turns the material return instrument alarm activation indicator light green when the total amount of material returned is greater than 65-75% of the design load of the material return equipment.

[0028] Preferably, the types of alarms from the material return instrument include: total material return alarm, liquid phase material return flow alarm from pyrolysis furnace, gas phase material return flow alarm from pyrolysis furnace, material return interlock pressure alarm, DMDS pressure alarm, DMDS flow alarm, anti-coking steam differential pressure alarm, pyrolysis furnace outlet temperature alarm, cross section temperature alarm, quench oil flow alarm, Venturi inlet pressure alarm, pyrolysis gas analysis indication alarm, cross section flue gas oxygen content alarm, fuel heat load ratio alarm, fuel heat load ratio alarm, low liquid feedstock flow alarm in furnace tubes, and low gas feedstock pressure alarm.

[0029] Preferably, the system further includes an operation navigation function module, which provides operation prompts during the material return stage according to the control instructions of the material return process control module.

[0030] Preferably, the system further includes a deep learning function module, which is used to learn the control advantages and disadvantages of each key parameter of the material return stage based on experience values ​​and big data, and to derive the optimal control values ​​of the key parameters of the material return stage.

[0031] To achieve the above objectives, a second aspect of the present invention provides an automatic execution method for the unloading process of an ethylene cracking furnace. This method is implemented using the aforementioned automatic execution system for the unloading process of the ethylene cracking furnace, and includes:

[0032] A pre-return status confirmation module is used to confirm the initial parameters before returning the material. When the initial parameters are within the initial range, it indicates that returning can proceed. When the initial parameters are outside the initial range, an alarm is triggered.

[0033] During the unloading process, a material unloading control module is used to control the key parameters of unloading and issue unloading commands. The key parameters of unloading include the unloading rate of the single tube in the furnace and the unloading rate of the main tube in the furnace.

[0034] The material return module receives the material return instruction and performs the material return during the material return stage.

[0035] According to the above technical solution, based on this system, in practical applications, the status before material return is confirmed by the pre-return status confirmation module. While ensuring that the cracking furnace can return material normally, the material return process control module can control the key parameters of material return during the material return process based on the current initial parameters. This ensures linear material return while avoiding large fluctuations in the key parameters of material return, which could cause significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow rate, resulting in unplanned shutdowns of the ethylene plant. This system has the advantages of high material return efficiency, small fluctuations in key parameters of material return, and high stability. Attached Figure Description

[0036] Figure 1 This is a flowchart of the automated system for the unloading process of an ethylene cracking furnace. Detailed Implementation

[0037] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0038] The first aspect of this invention provides an automatic execution system for the unloading process of an ethylene cracking furnace, such as... Figure 1 As shown, the automated system for the unloading process of the ethylene cracking furnace includes:

[0039] The pre-return status confirmation module is used to confirm the initial parameters before returning the material. When the initial parameters are within the initial range, it indicates that the material can be returned. When the initial parameters are not within the initial range, it issues an alarm.

[0040] The unloading process control module is used to control the key parameters of unloading during the unloading stage and issue unloading commands. The key parameters of unloading include the unloading rate of the single tube in the furnace and the unloading rate of the main tube in the furnace.

[0041] The material return module is used to receive material return instructions and perform material return.

[0042] According to the above technical solution, based on this system, in practical applications, the status before material return is confirmed by the pre-return status confirmation module. While ensuring that the cracking furnace can return material normally, the material return process control module can control the key parameters of material return during the material return process based on the current initial parameters. This ensures linear material return while avoiding large fluctuations in the key parameters of material return, which could cause significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow rate, resulting in unplanned shutdowns of the ethylene plant. This system has the advantages of high material return efficiency, small fluctuations in key parameters of material return, and high stability.

[0043] In a preferred embodiment of the automatic execution system for the ethylene cracking furnace unloading process described in this invention, the alarm activation when the initial parameters are outside the initial range specifically includes:

[0044] When the initial parameter is not within the initial range, an alarm is triggered for one or more of the initial parameters that are not within the initial range.

[0045] In one specific embodiment, the initial parameters include the single-tube dilution steam flow rate in the furnace, the pyrolysis furnace temperature, and the ultra-high pressure steam outlet temperature. In a more specific embodiment, the initial range of the ultra-high pressure steam temperature is 515–525°C, most preferably 519°C; the initial range of the pyrolysis furnace outlet temperature is 750–850°C, preferably 760–800°C; and the initial range of the single-tube dilution steam flow rate in the furnace is 2300–3000 kg / h, preferably 2400–2800 kg / h. This is to ensure that the pyrolysis furnace can recycle material normally, while allowing the material recycling process control module to control key parameters of the material recycling process based on the single-tube dilution steam flow rate in the furnace and the pyrolysis furnace outlet temperature.

[0046] In a preferred embodiment, the automatic execution system for the unloading process of an ethylene cracking furnace according to the present invention includes a first unloading stage, a second unloading stage, and a third unloading stage. In the first unloading stage, material is unloaded through the furnace main pipe to a first unloading value and stabilizes at the first unloading value for a preset time. In the second unloading stage, material is unloaded through the furnace main pipe to a second unloading value and stabilizes at the second unloading value for the preset time. In the third unloading stage, all remaining material to be unloaded is unloaded through the furnace single pipe.

[0047] In one specific implementation, the first return value is 60-85% of the total amount of material to be returned, preferably 65-75% of the total amount of material to be returned, the second return value is 10-30% of the total amount of material to be returned, preferably 10-20% of the total amount of material to be returned, and the preset time is 0-20 minutes, preferably 0-10 minutes. The furnace main pipe typically includes several furnace individual pipes. In practical applications, by unloading material at a low speed in the first unloading stage and then accelerating the unloading process in the second unloading stage, the stability of the entire system during the unloading process can be effectively guaranteed. Therefore, under certain circumstances, the unloading speeds in the first and second unloading stages can be the same. Unloading material through the furnace individual pipes in the third unloading stage is to ensure the accuracy of the unloading and avoid errors caused by unloading material through the furnace main pipe. Specifically, when unloading material through the furnace individual pipes, the unloading regulating valve on the furnace individual pipes is controlled to unload material at a valve position rate of 1 to 10% / min. Preferably, the unloading regulating valve on the furnace individual pipes is controlled to unload material at a valve position rate of 1 to 3% / min until all the material to be unloaded is removed.

[0048] In another preferred embodiment, the step of controlling key parameters for material removal and issuing a material removal command during the material removal stage specifically includes:

[0049] In the first and second unloading stages, the unloading rate of the furnace main pipe is controlled so that the dilution steam flow rate of the furnace single pipe increases at a first preset rate and a second preset rate, respectively. In the third unloading stage, the unloading rate of the furnace single pipe is controlled, and when the unloading is completed, the dilution steam flow rate of the furnace single pipe is made to be 1.5 to 2.5 times its initial range.

[0050] In one specific embodiment, during the first and second unloading stages, the unloading rates of the furnace main pipe are 50–500 kg / h / min and 500–2000 kg / h / min, respectively. Preferably, the unloading rates of the furnace main pipe are 100–300 kg / h / min and 700–1500 kg / h / min, respectively. In the third unloading stage, the unloading rate of the furnace single pipe is 15–125 kg / h / min, while the first preset rate is 10–120 kg / h / min, preferably 10–50 kg / h / min, and the second preset rate is 50–150 kg / h / min, preferably 50–100 kg / h / min. In practical applications, by controlling the material return rate at different stages of material return, the rising rate of the dilution steam flow rate in the single tube of the furnace can be controlled. Finally, when the material return is completed, the dilution steam flow rate in the single tube of the furnace is 1.5 to 2.5 times its initial range. This allows the dilution steam flow rate in the single tube of the furnace to change linearly during the rising process, without the need for manual material return based on experience, which would cause violent fluctuations in the dilution steam flow rate in the single tube of the furnace.

[0051] In another, more preferred embodiment, the key parameters for material removal also include the rate of decrease in the calorific value of the fuel gas, the fuel gas pressure, the oxygen content in the furnace, and the carbon monoxide content in the pyrolysis gas. The control of these key parameters and the issuance of a material removal command during the material removal stage specifically includes:

[0052] During the unloading process via the single furnace tube or the main furnace tube, the rate of decrease in the calorific value of the fuel gas is controlled at 0.5–2.0 MW / 1000 kg unloaded, the fuel gas pressure is controlled at 0.06–0.22 MPa, the oxygen content in the furnace is controlled at 1.5–5%, and the carbon monoxide content in the pyrolysis gas is controlled at 0.05–0.07 mol%. This ensures that the outlet temperature of the pyrolysis furnace decreases to a set target temperature at a preset cooling rate, based on its initial temperature. The preset cooling rate is 0.3–2 °C / min, and the set target temperature is 720–750 °C. The actual meaning of "0.5–2.0 MW / 1000 kg unloaded" is that the calorific value of the fuel gas decreases by 0.5–2.0 MW for every 1000 kg of unloaded material. The preferred rate of decrease in the calorific value of the fuel gas is 0.8–1.2 MW / 1000 kg of unloaded material; the preferred oxygen content in the furnace is 1.5–3%; and the preferred preset cooling rate is 0.5–1.2 °C / min. The automatic pressure protection value for the fuel gas pressure is 0.06 MPa.

[0053] In practical applications, the unloading process control module dynamically adjusts the pyrolysis furnace outlet temperature by further controlling the rate of decrease in the calorific value of the fuel gas, the fuel gas pressure, the oxygen content in the furnace, and the carbon monoxide content in the pyrolysis gas. Preferably, the pyrolysis furnace outlet temperature is reduced to 720-750℃ at a preset cooling rate. More preferably, throughout the unloading process, the pyrolysis furnace outlet temperature linearly decreases from the initial temperature to 720-750℃, without the violent fluctuations seen in manual unloading. In one specific embodiment, the pyrolysis furnace outlet temperature can be adjusted using feedback values ​​of the carbon monoxide content in the pyrolysis gas, and the damper opening of the pyrolysis furnace can also be adjusted using feedback values ​​of the oxygen content in the furnace.

[0054] In a preferred embodiment, the automatic execution system for the ethylene cracking furnace unloading process of the present invention further includes a key parameter monitoring and alarm module for unloading, used to monitor the key parameters during the unloading stage and to issue an alarm when the key parameters exceed a preset range. In a specific embodiment, monitoring the key parameters and issuing an alarm when they exceed a preset range specifically includes: issuing an alarm when the key parameters exceed a first preset range; and adjusting the key parameters exceeding the second preset range to the first preset range based on their current value according to a preset ratio when the key parameters exceed a second preset range, and then issuing an alarm. The upper limit of the second preset range is greater than the upper limit of the first preset range, and the lower limit of the second preset range is less than the lower limit of the first preset range, with the preset ratio being ±0.1% to 10%. In another specific implementation, the key parameters for material return also include the pressure after the Venturi tube, the dilution steam flow rate of the single tube in the furnace, the outlet temperature of the pyrolysis furnace, the ultra-high pressure steam temperature, the VHS drum level, VHS temperature, VHS drum pressure, the temperature after the oil cooler, and the temperature of the pyrolysis furnace cross section, thereby further improving the safety of the entire system. Taking the furnace oxygen content among the key parameters for material return as an example, the first preset range is 1.5%–3%, and the second preset range is 1%–6%. When the key parameter monitoring and alarm module detects that the furnace oxygen content is 1.4%, an alarm is triggered; when the key parameter monitoring and alarm module detects that the furnace oxygen content is 0.8%, the furnace oxygen content is expanded from 0.8% to 0.1%–10% within the first preset range, thereby improving the safety of the system throughout the material return process.

[0055] Furthermore, the key parameter monitoring and alarm module for material return can be configured with alarm display status according to 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 level one alarm is used, and when the oxygen content in the furnace exceeds the second preset range, a level two alarm is used. Specifically, the level one alarm uses a yellow background with black text, flashing, and a low-frequency sound, while the level two alarm uses an orange background with black text, flashing, and a medium-frequency sound. The boundary values ​​of the first and second preset ranges should not overlap with the instrument range of the alarm device of the key parameter monitoring and alarm module for material return, and should be set within 10% to 90% of the maximum range of the instrument.

[0056] In a preferred embodiment, the automatic execution system for the ethylene cracking furnace unloading process of the present invention further includes an alarm optimization management module for the unloading process. This module automatically disables the unloading instrument alarm and turns the alarm activation indicator light red when the total unloading amount is less than 40-65% of the design load of the unloading equipment. Conversely, when the total unloading amount exceeds 65-75% of the design load of the unloading equipment, it activates the unloading instrument alarm and turns the alarm activation indicator light green. This allows operators to easily determine whether the alarm is functioning correctly during practical applications, avoiding interference from invalid alarms that could affect unloading efficiency. In one specific implementation, the types of alarms from the unloading instruments include: total unloading alarm, pyrolysis furnace liquid phase unloading flow alarm, pyrolysis furnace gas phase unloading flow alarm, unloading interlock pressure alarm, DMDS pressure alarm, DMDS flow alarm, anti-coking steam differential pressure alarm, pyrolysis furnace outlet temperature alarm, cross-section temperature alarm, quench oil flow alarm, Venturi inlet pressure alarm, pyrolysis gas analysis indication alarm, cross-section flue gas oxygen content alarm, fuel heat load ratio alarm, fuel heat load ratio alarm, low furnace tube liquid feedstock flow alarm, and low gas feedstock pressure alarm. The design load of the unloading equipment is typically fixed.

[0057] In a preferred embodiment of the automatic execution system for the unloading process of the ethylene cracking furnace described in this invention, the system further includes a parameter setting module for setting the preset range of the key unloading parameters. Thus, in actual production, the operator can set the key unloading parameters and the allowable deviations or upper and lower limits of each key unloading parameter according to the actual production needs.

[0058] In a preferred embodiment, the automatic execution system for the unloading process of the ethylene cracking furnace described in this invention further includes an operation navigation function module, which provides operation prompts during the unloading stage according to the control instructions of the unloading process control module, thereby improving unloading efficiency and safety during the unloading process.

[0059] In a preferred embodiment, the automatic execution system for the ethylene cracking furnace unloading process of the present invention further includes a deep learning function module, which is used to learn the control advantages and disadvantages of each key unloading parameter in the unloading stage based on experience values ​​and big data, and to derive the optimal control values ​​of the key unloading parameters in the unloading stage, thereby maximizing the linear exit of unloading and reducing the fluctuation of the key unloading parameters.

[0060] A second aspect of the present invention provides an automatic execution method for the unloading process of an ethylene cracking furnace, the method being implemented using the aforementioned automatic execution system for the unloading process of the ethylene cracking furnace, the method comprising:

[0061] A pre-return status confirmation module is used to confirm the initial parameters before returning the material. When the initial parameters are within the initial range, it indicates that returning can proceed. When the initial parameters are outside the initial range, an alarm is triggered.

[0062] During the unloading process, a material unloading control module is used to control the key parameters of unloading and issue unloading commands. The key parameters of unloading include the unloading rate of the single tube in the furnace and the unloading rate of the main tube in the furnace.

[0063] The material return module receives the material return instruction and performs the material return during the material return stage.

[0064] The automatic execution method for the ethylene cracking furnace unloading process described in this invention, in practical application, confirms the state before unloading through a pre-unloading status confirmation module. While ensuring that the cracking furnace can unload normally, the unloading process control module can control the key unloading parameters during the unloading process based on the current initial parameters. This ensures linear unloading while avoiding large fluctuations in the key unloading parameters, which could cause significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow rate, leading to unplanned shutdowns of the ethylene plant. It has the advantages of high unloading efficiency, small fluctuations in key unloading parameters, and high stability.

[0065] In a preferred embodiment of the automatic execution method for the unloading process of an ethylene cracking furnace described in this invention, a key parameter monitoring and alarm module for unloading is employed. This module monitors the key parameters during the unloading stage and triggers an alarm when the key parameters exceed a preset range. Specifically, an alarm is triggered when the key parameters exceed a first preset range; when the key parameters exceed a second preset range, the parameters exceeding the second preset range are adjusted to the first preset range by ±0.1% to 10% of their current value, and an alarm is triggered again, thereby improving the safety performance of the entire system.

[0066] In a preferred embodiment, the automatic execution method for the ethylene cracking furnace unloading process of the present invention employs a deep learning functional module to learn the control advantages and disadvantages of each key unloading parameter in the unloading stage based on empirical values ​​and big data, and derives the optimal control values ​​of the key unloading parameters in the unloading stage, thereby maximizing the linear exit of unloading and reducing the fluctuations of the key unloading parameters.

[0067] In this invention, the system may further include a post-return inspection module, used to inspect the status of the pyrolysis furnace after the return of materials is completed, so as to further ensure production safety.

[0068] The automatic execution system for the ethylene cracking furnace unloading process described in this invention, in one specific embodiment, comprises a human-machine interface and a program control system, thereby achieving online control through a combination of field distributed control system (DCS) configuration and upper-level server programming. To automate the ethylene cracking furnace unloading process, an independent server is deployed on the industrial control network. The ethylene cracking furnace unloading process execution program interacts with data through the OPC DA interface of the Emerson DCS OPC server to obtain the values ​​or status of relevant parameters. To ensure the secure operation of the DCS system, an industrial-grade firewall is added between the system server and the communication interface. By configuring corresponding rules and policies, deep isolation and protection of the DCS control system are achieved, cutting off virus propagation paths and ensuring the normal, safe, and stable operation of the plant's DCS production control system. The industrial firewall incorporates proprietary communication protocols from various mainstream automation product manufacturers, enabling seamless access to systems such as Honeywell DCS, Yokogawa DCS, and Emerson DCS, as well as OPC SERVER, IP21 / PHD / PI servers or databases.

[0069] The human-machine interface (HMI) includes function buttons for parameter "setting," cracking furnace status "confirmation," program "run," "pause," "continue," "stop," and parameter "alarm" to enable HMI interaction. Specifically, clicking the "parameter setting" button allows manual setting of key program parameter control thresholds and upper / lower limit presets; clicking the "cracking furnace status confirmation" button confirms the status before material return, and the interface jumps to the material return operation interface; otherwise, the material return program cannot run; clicking the "program run" button starts the material return program; clicking "pause" stops the system from proceeding to the next step, keeping all parameter control values ​​at their current values; clicking "continue" resumes the program; manually clicking "stop" stops the automatic material return program and switches to manual operation; clicking the "alarm" button switches the HMI to the alarm interface, allowing detailed viewing of system alarms and enabling or disabling alarm masking during the material return process.

[0070] Furthermore, the human-machine interface also includes system operation status display, system operation buttons, key parameter trend graphs, and system alarm prompts. Among these, the "Run," "Stop," "Pause," "Continue," and "Parameter Setting" function buttons on the human-machine interface can be executed by the user at any time during system operation, based on the actual operating conditions of the ethylene unit and compressor.

[0071] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0072] Example 1

[0073] Based on an ethylene cracking furnace with a production capacity of 140,000 tons / year, the present invention is adopted as follows: Figure 1 The automated execution system for the ethylene cracking furnace unloading process, as shown, specifically includes:

[0074] The pre-return status confirmation module is used to confirm the initial parameters before returning the material. When the initial parameters are within the initial range, it indicates that the material can be returned. When the initial parameters are not within the initial range, it issues an alarm.

[0075] The unloading process control module is used to control the key parameters of unloading during the unloading stage and issue unloading commands. The key parameters of unloading include the unloading rate of the single tube in the furnace and the unloading rate of the main tube in the furnace.

[0076] The material return module is used to receive material return instructions and perform material return.

[0077] The alarm is triggered when the initial parameter is not within the initial range, specifically including:

[0078] When the initial parameters are outside the initial range, an alarm is triggered for one or more of the initial parameters that are outside the initial range. The initial parameters include the furnace single-tube dilution steam flow rate, the pyrolysis furnace outlet temperature, and the ultra-high pressure steam outlet temperature. The initial range for the ultra-high pressure steam outlet temperature is 519°C, the initial range for the pyrolysis furnace outlet temperature is 760°C, and the initial range for the furnace single-tube dilution steam flow rate is 2500 kg / h.

[0079] The material return stage includes a first material return stage, a second material return stage, and a third material return stage. In the first material return stage, material is returned to a first material return value through the furnace main pipe and stabilized at the first material return value for a preset time. In the second material return stage, material is returned to a second material return value through the furnace main pipe and stabilized at the second material return value for the preset time. In the third material return stage, all remaining material to be returned is returned through the furnace single pipe.

[0080] During the material return phase, key parameters for material return are controlled, and a material return command is issued, specifically including:

[0081] In the first and second unloading stages, the unloading rate of the furnace main pipe is controlled so that the dilution steam flow rate of the furnace single pipe increases at a first preset rate and a second preset rate, respectively. In the third unloading stage, the unloading rate of the furnace single pipe is controlled, and when the unloading is completed, the dilution steam flow rate of the furnace single pipe is made to be 1.5 to 2.5 times its initial range.

[0082] Specifically, the material to be returned is 30,000 kg / h, the first return value is 70% of the total material to be returned, the second return value is 15% of the total material to be returned, the preset time is 8 min, in the first return stage, the return rate of the furnace main pipe is 200 (kg / h) / min, the first preset rate is 40 (kg / h) / min, in the second return stage, the return rate of the furnace main pipe is 800 (kg / h) / min, the second preset rate is 80 (kg / h) / min, in the third stage, the return rate of the furnace single pipe is 60 (kg / h) / min, and when the return is completed, the dilution steam flow rate of the furnace single pipe is made 1.9 times its initial range.

[0083] In practical application, the pre-return status confirmation module first confirms the initial parameters before returning. When the initial parameters are within the initial range, it indicates that returning can proceed. Then, the returning process control module returns the material through the furnace main pipe at a rate of 200 kg / h / min during the first returning stage, returning the material to 70% of the total amount to be returned, and then stabilizing for 8 minutes. At the same time, the dilution steam flow rate of the furnace single pipe increases at a rate of 40 kg / h / min. During the second returning stage, the material is returned through the furnace main pipe at a rate of 800 kg / h / min, returning the material to 15% of the total amount to be returned, and then stabilizing for 8 minutes. At the same time, the dilution steam flow rate of the furnace single pipe increases at a rate of 80 kg / h / min. During the third returning stage, the remaining material to be returned is completely removed through the furnace single pipe at a rate of 60 kg / h / min.

[0084] Testing revealed that the automatic execution system for the ethylene cracking furnace unloading process described in this invention, in practical applications, confirms the state before unloading through the pre-unloading status confirmation module. This ensures that the cracking furnace can unload normally while enabling the unloading process control module to control the key unloading parameters during the unloading process based on the initial value of the current single-tube dilution steam flow rate in the furnace. This ensures linear unloading while avoiding large fluctuations in the key unloading parameters, which could cause significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow rate, leading to unplanned shutdowns of the ethylene plant. The system has the advantages of high unloading efficiency, small fluctuations in key unloading parameters, and high stability.

[0085] Example 2

[0086] Referring to Example 1, the key parameters for material removal also include the rate of decrease in the calorific value of the fuel gas, the fuel gas pressure, the oxygen content in the furnace, and the carbon monoxide content in the pyrolysis gas. Specifically, during the material removal stage, controlling these key parameters and issuing a material removal command further includes: controlling the rate of decrease in the calorific value of the fuel gas to 0.5–2.0 MW / 1000 kg during material removal via the single furnace pipe or the main furnace pipe; controlling the fuel gas pressure to 0.06–0.22 MPa; controlling the oxygen content in the furnace to 1.5–5%; and controlling the carbon monoxide content in the pyrolysis gas to 0.05–0.07 mol%, so that the outlet temperature of the pyrolysis furnace decreases to a set target temperature at a preset cooling rate based on its initial temperature. The preset cooling rate is 0.5–1.2 °C / min, and the set target temperature is 720–750 °C.

[0087] Specifically, the rate of decrease in the calorific value of the fuel gas is 1.0 MW / 1000 kg of unloaded material, the fuel gas pressure is 0.06 MPa, the oxygen content in the furnace is 2%, the carbon monoxide content in the cracked gas is 0.06 mol%, the preset cooling rate is 1℃ / min, and the target temperature is set at 720℃.

[0088] Testing revealed that the automatic execution system for the ethylene cracking furnace unloading process described in this invention, in practical applications, confirms the state before unloading through the pre-unloading status confirmation module. This ensures normal unloading from the cracking furnace while enabling the unloading process control module to control the key unloading parameters during the unloading process based on the initial values ​​of the current single-tube dilution steam flow rate in the furnace and the cracking furnace outlet temperature. This ensures linear unloading while preventing large fluctuations in the key unloading parameters, which could lead to significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow rate, causing unplanned shutdowns of the ethylene plant. The system offers advantages such as high unloading efficiency, smaller fluctuations in key unloading parameters, and higher stability.

[0089] Example 3

[0090] The system is implemented in accordance with Embodiment 2, but with the difference that it also includes a key parameter monitoring and alarm module for unloading materials. This module is used to monitor the key parameters for unloading materials during the unloading stage and to issue an alarm when the key parameters for unloading materials exceed a preset range. The key parameters for unloading materials also include the pressure after the Venturi tube, the dilution steam flow rate of the single tube in the furnace, the outlet temperature of the pyrolysis furnace, the outlet temperature of the ultra-high pressure steam, the liquid level of the VHS drum, the pressure of the VHS drum, the VHS temperature, the temperature after the oil cooler, and the temperature of the pyrolysis furnace cross section.

[0091] Testing revealed that the automatic execution system for the ethylene cracking furnace unloading process described in this invention, in practical applications, confirms the pre-unloading status through a pre-unloading status confirmation module. This ensures normal unloading from the cracking furnace while allowing the unloading process control module to control key unloading parameters during the unloading process based on the initial values ​​of the current single-tube dilution steam flow rate and the cracking furnace outlet temperature. This ensures linear unloading while preventing large fluctuations in key unloading parameters, which could lead to significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow rate, causing unplanned shutdowns of the ethylene plant. The system offers advantages such as high unloading efficiency, smaller fluctuations in key unloading parameters, higher stability, and higher safety.

[0092] Example 4

[0093] Referring to Embodiment 3, the difference is that the monitoring of the key parameters of the material return, and the alarm being triggered when the key parameters of the material return exceed the preset range, specifically includes:

[0094] An alarm is triggered when the key parameters for material return exceed the first preset range;

[0095] When the material return key parameter exceeds the second preset range, the material return key parameter exceeding the second preset range is adjusted to the first preset range according to a preset ratio based on its current value, and an alarm is triggered; the upper limit of the second preset range is greater than the upper limit of the first preset range, and the lower limit of the second preset range is less than the lower limit of the first preset range, and the preset ratio is ±0.1% to 10%.

[0096] Testing revealed that the automatic execution system for the ethylene cracking furnace unloading process described in this invention, in practical applications, confirms the pre-unloading status through the pre-unloading status confirmation module. This ensures normal unloading from the cracking furnace while allowing the unloading process control module to control key unloading parameters based on the initial values ​​of the current furnace single-tube dilution steam flow and the cracking furnace outlet temperature. This ensures linear unloading while preventing large fluctuations in key unloading parameters, which could lead to significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow, causing unplanned shutdowns of the ethylene plant. The system offers advantages such as high unloading efficiency, smaller fluctuations in key unloading parameters, higher stability, and greater safety.

[0097] Example 5

[0098] The system is implemented in accordance with Embodiment 4, but with the difference that it also includes a deep learning function module, which is used to learn the control advantages and disadvantages of the key parameters of the material return stage based on experience values ​​and big data, and to derive the optimal control values ​​of the key parameters of the material return stage.

[0099] Testing revealed that the automatic execution system for the ethylene cracking furnace unloading process described in this invention, in practical applications, confirms the pre-unloading status through the pre-unloading status confirmation module. This ensures normal unloading from the cracking furnace while allowing the unloading process control module to control key unloading parameters based on the initial values ​​of the current furnace single-tube dilution steam flow and the cracking furnace outlet temperature. This ensures linear unloading while preventing large fluctuations in key unloading parameters, which could lead to significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow, causing unplanned shutdowns of the ethylene plant. The system offers advantages such as high unloading efficiency, smaller fluctuations in key unloading parameters, higher stability, and greater safety.

[0100] Example 6

[0101] The implementation follows the same procedure as Example 5, except that in the first and second unloading stages, the unloading rate of the main furnace tube is 100 (kg / h) / min and 700 (kg / h) / min, respectively, and in the third unloading stage, the unloading rate of the single furnace tube is 50 (kg / h) / min.

[0102] Testing revealed that the automatic execution system for the ethylene cracking furnace unloading process described in this invention, in practical applications, confirms the pre-unloading status through the pre-unloading status confirmation module. This ensures normal unloading from the cracking furnace while allowing the unloading process control module to control key unloading parameters based on the initial values ​​of the current furnace single-tube dilution steam flow and the cracking furnace outlet temperature. This ensures linear unloading while preventing large fluctuations in key unloading parameters, which could lead to significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow, causing unplanned shutdowns of the ethylene plant. The system offers advantages such as high unloading efficiency, smaller fluctuations in key unloading parameters, higher stability, and greater safety.

[0103] Example 7

[0104] The implementation follows the same procedure as Example 5, except that in the first and second unloading stages, the unloading rate of the main furnace tube is 150 (kg / h) / min and 900 (kg / h) / min, respectively, and in the third unloading stage, the unloading rate of the single furnace tube is 50 (kg / h) / min.

[0105] Testing revealed that the automatic execution system for the ethylene cracking furnace unloading process described in this invention, in practical applications, confirms the pre-unloading status through the pre-unloading status confirmation module. This ensures normal unloading from the cracking furnace while allowing the unloading process control module to control key unloading parameters based on the initial values ​​of the current furnace single-tube dilution steam flow and the cracking furnace outlet temperature. This ensures linear unloading while preventing large fluctuations in key unloading parameters, which could lead to significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow, causing unplanned shutdowns of the ethylene plant. The system offers advantages such as high unloading efficiency, smaller fluctuations in key unloading parameters, higher stability, and greater safety.

[0106] Example 8

[0107] The implementation follows the same procedure as Example 5, except that in the first and second unloading stages, the unloading rate of the main furnace tube is 250 (kg / h) / min and 1200 (kg / h) / min, respectively, and in the third unloading stage, the unloading rate of the single furnace tube is 70 (kg / h) / min.

[0108] Testing revealed that the automatic execution system for the ethylene cracking furnace unloading process described in this invention, in practical applications, confirms the pre-unloading status through the pre-unloading status confirmation module. This ensures normal unloading from the cracking furnace while allowing the unloading process control module to control key unloading parameters based on the initial values ​​of the current furnace single-tube dilution steam flow and the cracking furnace outlet temperature. This ensures linear unloading while preventing large fluctuations in key unloading parameters, which could lead to significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow, causing unplanned shutdowns of the ethylene plant. The system offers advantages such as high unloading efficiency, smaller fluctuations in key unloading parameters, higher stability, and greater safety.

[0109] Example 9

[0110] The implementation follows the same procedure as Example 5, except that in the first and second unloading stages, the unloading rate of the main furnace tube is 300 (kg / h) / min and 1500 (kg / h) / min, respectively, and in the third unloading stage, the unloading rate of the single furnace tube is 80 (kg / h) / min.

[0111] Testing revealed that the automatic execution system for the ethylene cracking furnace unloading process described in this invention, in practical applications, confirms the pre-unloading status through the pre-unloading status confirmation module. This ensures normal unloading from the cracking furnace while allowing the unloading process control module to control key unloading parameters based on the initial values ​​of the current furnace single-tube dilution steam flow and the cracking furnace outlet temperature. This ensures linear unloading while preventing large fluctuations in key unloading parameters, which could lead to significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow, causing unplanned shutdowns of the ethylene plant. The system offers advantages such as high unloading efficiency, smaller fluctuations in key unloading parameters, higher stability, and greater safety.

[0112] Example 10

[0113] The implementation follows the same procedure as in Example 5, except that when the material return key parameter exceeds the second preset range, the material return key parameter exceeding the second preset range is adjusted to the first preset range by ±3% based on its current value, and an alarm is triggered.

[0114] Testing revealed that the automatic execution system for the ethylene cracking furnace unloading process described in this invention, in practical applications, confirms the pre-unloading status through the pre-unloading status confirmation module. This ensures normal unloading from the cracking furnace while allowing the unloading process control module to control key unloading parameters based on the initial values ​​of the current furnace single-tube dilution steam flow and the cracking furnace outlet temperature. This ensures linear unloading while preventing large fluctuations in key unloading parameters, which could lead to significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow, causing unplanned shutdowns of the ethylene plant. The system offers advantages such as high unloading efficiency, smaller fluctuations in key unloading parameters, higher stability, and greater safety.

[0115] The automatic execution system and method for the unloading process of an ethylene cracking furnace provided by this invention confirms the state before unloading through a pre-unloading state confirmation module. While ensuring that the cracking furnace can unload normally, the unloading process control module can control the key unloading parameters during the unloading process based on the initial values ​​of the current single-tube dilution steam flow rate in the furnace and the cracking furnace outlet temperature. This ensures linear unloading while avoiding large fluctuations in the key unloading parameters, which could cause significant fluctuations in parameters such as the cracking furnace outlet temperature and dilution steam flow rate, resulting in unplanned shutdowns of the ethylene plant. It has the advantages of high unloading efficiency, smaller fluctuations in key unloading parameters, higher stability, and higher safety.

[0116] 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 inventive concept, various simple modifications can be made to the technical solutions of the present invention. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An automated system for the unloading process of an ethylene cracking furnace, characterized in that, The system includes: The pre-return status confirmation module is used to confirm the initial parameters before returning the material. When the initial parameters are within the initial range, it indicates that the material can be returned. When the initial parameters are not within the initial range, it issues an alarm. The unloading process control module is used to control the key parameters of unloading during the unloading stage and issue unloading commands. The key parameters of unloading include the unloading rate of the single tube in the furnace and the unloading rate of the main tube in the furnace. The material return module is used to receive material return instructions and perform material return. The initial parameters include the single-tube dilution steam flow rate in the furnace, the pyrolysis furnace outlet temperature, and the ultra-high pressure steam temperature. The material return stage includes a first material return stage, a second material return stage, and a third material return stage. In the first material return stage, material is returned to a first material return value through the furnace main pipe and stabilized at the first material return value for a preset time. In the second material return stage, material is returned to a second material return value through the furnace main pipe and stabilized at the second material return value for the preset time. In the third material return stage, all remaining material to be returned is returned through the furnace single pipe. During the material return phase, key parameters for material return are controlled, and a material return command is issued, specifically including: In the first and second unloading stages, the unloading rate of the furnace main pipe is controlled so that the dilution steam flow rate of the furnace single pipe increases at a first preset rate and a second preset rate, respectively. In the third unloading stage, the unloading rate of the furnace single pipe is controlled, and when the unloading is completed, the dilution steam flow rate of the furnace single pipe is made to be 1.5 to 2.5 times its initial range. The key parameters for material return also include the rate of decrease in the calorific value of the fuel gas, the fuel gas pressure, the oxygen content in the furnace, and the carbon monoxide content in the pyrolysis gas.

2. The system according to claim 1, characterized in that, The alarm is triggered when the initial parameter is not within the initial range, specifically including: When the initial parameter is not within the initial range, an alarm is triggered for one or more of the initial parameters that are not within the initial range.

3. The system according to claim 1, characterized in that, The initial range of the ultra-high pressure steam temperature is 515~525℃, the initial range of the pyrolysis furnace outlet temperature is 750~850℃, and the initial range of the single-tube dilution steam flow rate in the furnace is 2300~3000kg / h.

4. The system according to claim 1, characterized in that, The first return value is 60-85% of the total amount of material to be returned, the second return value is 10-30% of the total amount of material to be returned, and the preset time is 0-20 minutes.

5. The system according to claim 1, characterized in that, In the first and second unloading stages, the unloading rate of the main furnace tube is 50~500 (kg / h) / min and 500~2000 (kg / h) / min, respectively. In the third unloading stage, the unloading rate of the single furnace tube is 15~125 (kg / h) / min, the first preset rate is 10~120 (kg / h) / min, and the second preset rate is 50~150 (kg / h) / min.

6. The system according to claim 1, characterized in that, During the material return phase, key parameters for material return are controlled, and a material return command is issued. Specifically, this also includes: During the material return process via the single furnace tube or the main furnace tube, the rate of decrease in the calorific value of the fuel gas is controlled at 0.5~2.0MW / 1000kg, the fuel gas pressure is controlled at 0.06~0.22MPa, the oxygen content in the furnace is controlled at 1.5~5%, and the carbon monoxide content in the pyrolysis gas is controlled at 0.05~0.07mol%, so that the outlet temperature of the pyrolysis furnace is reduced to a set target temperature at a preset cooling rate based on its initial temperature, wherein the preset cooling rate is 0.3~2℃ / min, and the set target temperature is 720~750℃.

7. The system according to claim 1, characterized in that, The system also includes a key parameter monitoring and alarm module for unloading materials, which is used to monitor the key parameters of unloading materials during the unloading stage and to issue an alarm when the key parameters of unloading materials exceed the preset range.

8. The system according to claim 7, characterized in that, The monitoring of the key parameters for material return, and the alarm triggered when the key parameters for material return exceed a preset range, specifically includes: An alarm is triggered when the key parameters for material return exceed the first preset range; When the material return key parameter exceeds the second preset range, the material return key parameter exceeding the second preset range will be adjusted to the first preset range according to a preset ratio based on its current value, and an alarm will be triggered.

9. The system according to claim 8, characterized in that, The upper limit of the second preset range is greater than the upper limit of the first preset range, the lower limit of the second preset range is less than the lower limit of the first preset range, and the preset ratio is ±0.1%~10%.

10. The system according to any one of claims 1, 4-9, characterized in that, The system also includes an alarm optimization management module for the material return process. When the total amount of material returned is less than 40-65% of the design load of the material return equipment of the material return module, the alarm of the material return instrument will be automatically blocked and the alarm activation indicator light of the material return instrument will turn red. When the total amount of material returned is greater than 65-75% of the design load of the material return equipment, the alarm of the material return instrument will be activated and the alarm activation indicator light of the material return instrument will turn green.

11. The system according to claim 10, characterized in that, The types of alarms from the unloading instruments include: total unloading alarm, liquid phase unloading flow alarm from the pyrolysis furnace, gas phase unloading flow alarm from the pyrolysis furnace, unloading interlock pressure alarm, DMDS pressure alarm, DMDS flow alarm, anti-coke steam differential pressure alarm, pyrolysis furnace outlet temperature alarm, cross section temperature alarm, quench oil flow alarm, Venturi inlet pressure alarm, pyrolysis gas analysis indication alarm, cross section flue gas oxygen content alarm, fuel heat load ratio alarm, low liquid feedstock flow alarm in furnace tubes, and low gas feedstock pressure alarm.

12. The system according to claim 1, characterized in that, The system also includes an operation navigation function module, which provides operation prompts during the material return stage based on the control instructions from the material return process control module.

13. The system according to claim 1, characterized in that, The system also includes a deep learning module, which is used to learn the advantages and disadvantages of controlling the key parameters of the material return stage based on experience values ​​and big data, and to derive the optimal control values ​​of the key parameters of the material return stage.

14. An automatic execution method for the unloading process of an ethylene cracking furnace, characterized in that, This method is implemented using the system described in any one of claims 1 to 13, and the method includes: A pre-return status confirmation module is used to confirm the initial parameters before returning the material. When the initial parameters are within the initial range, it indicates that returning can proceed. When the initial parameters are outside the initial range, an alarm is triggered. During the unloading process, a material unloading control module is used to control the key parameters of unloading and issue unloading commands. The key parameters of unloading include the unloading rate of the single tube in the furnace and the unloading rate of the main tube in the furnace. The material return module receives the material return instruction and performs the material return during the material return stage.

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