Dcs control method and system applied to thermal cracking for ethylene production

Abstract

The application discloses a DCS control method and system applied to thermal cracking for ethylene production, through real-time monitoring and adjustment of key parameters such as quality, flow, cracking temperature and pressure of raw materials, stability and consistency in the production process are ensured, thereby improving the yield and purity of ethylene, accurately controlling cracking conditions (such as the proportion of steam and raw materials) and cooling rate, which can effectively reduce energy consumption and waste emission, through effective regulation of the separation process, further improving the resource utilization rate.

Description

Technical Field

[0001] This invention relates to the field of control systems, and more particularly to a DCS control method and system for ethylene production by thermal cracking. Background Technology

[0002] Currently, in the face of fierce market competition, how to efficiently and stably produce high-quality ethylene has become a key focus for chemical companies. The process of producing ethylene through thermal cracking requires a large amount of energy, including fuel gas for heating furnaces and cooling medium for gas cooling. The cracking reaction involves a high-temperature and high-pressure environment, which poses certain safety hazards. In actual production, due to factors such as fluctuations in raw material quality and changes in the external environment, production conditions are often complex and changeable. Traditional manual or semi-automatic control methods are difficult to meet the requirements for precise control of the cracking process.

[0003] In summary, there is a need for a DCS control method and system for ethylene production by thermal cracking to address the shortcomings of existing technologies. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a DCS control method and system for ethylene production via thermal cracking, aiming to solve the aforementioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a DCS control method for ethylene production by thermal cracking, comprising the following steps:

[0006] Step S1: Pre-treat the raw materials entering the cracking furnace, and monitor and control the quality and flow rate of the raw materials;

[0007] Step S2: The raw material is mixed with ultra-high temperature steam, and the pyrolysis temperature, pressure and the ratio of steam to raw material are monitored and adjusted;

[0008] Step S3: Control the cooling rate and final temperature of the high-temperature gas after pyrolysis;

[0009] Step S4: Real-time monitoring and control of the separation process and impurity removal in the fractionation tower, absorption tower, and adsorption tower;

[0010] Step S5: Real-time monitoring and control of the operating parameters for compressor pressurization and dryer dehydration of the separated ethylene;

[0011] Step S6: Obtain historical data for each detection control point, and calculate the parameter range of the thermal decomposition reaction for each detection control point based on the historical data;

[0012] Step S7: Select important detection control points for detection based on the parameter range of the thermal decomposition reaction at each detection control point.

[0013] Optionally, the quality and flow rate of the raw materials are monitored and controlled in step S1 by the following methods:

[0014] The composition and purity of raw materials are monitored in real time by an online analyzer, the flow rate of raw materials is measured by a mass flow meter, sensor data is collected and analyzed, and the valve opening and pump speed are automatically adjusted to control the feed rate and composition.

[0015] Optionally, in step S2, the pyrolysis temperature, pressure, and steam-to-feed ratio are monitored and adjusted in the following ways:

[0016] Temperature monitoring and adjustment: Multiple temperature detection points are set in the pyrolysis furnace, and temperature thresholds are set. The DCS system detects the temperature at the detection points and automatically adjusts the combustion load or issues an alarm based on the detected temperature and the temperature threshold.

[0017] Pressure monitoring and adjustment: The DCS system detects the outlet pressure of the cracking furnace and determines whether the pressure is within the pressure balance range. If the pressure is higher than the pressure balance range, the system will adjust the inlet valve or relief valve of the quench tower in conjunction with the pressure balance range. Conversely, the system will adjust the feed pump frequency or bypass valve.

[0018] Steam and raw material ratio monitoring and adjustment: Measure the mass flow rate of raw materials and steam respectively, calculate the actual water-carbon ratio, compare it with the set value, and if the ratio deviates from the set value, adjust the steam regulating valve or the raw material pump speed to compensate.

[0019] Optionally, in step S3, the cooling rate and final temperature of the pyrolyzed high-temperature gas are controlled by the following methods:

[0020] Temperature monitoring points are set at the inlet and outlet of the quench tower. The DCS system monitors the temperature of the cracked gas when it enters and the temperature change after quenching. It automatically adjusts the flow rate of the cooling medium to control the cooling rate. Increasing the flow rate of the cooling medium speeds up the cooling rate, and vice versa.

[0021] Optionally, in step S4, the separation process and impurity removal of the fractionation tower, absorption tower, and adsorption tower are monitored and controlled in real time through the following methods:

[0022] Fractionation column: Obtain the operating parameters of the fractionation column, compare and analyze them with preset values, adjust the heating or cooling amount according to the temperature changes at the top and bottom of the column, adjust the reflux flow rate to maintain the reflux ratio, control the feed rate and composition, and improve the fractionation efficiency.

[0023] Absorption tower: Continuously and in real time acquire the working parameters of the inlet and outlet status of the absorption tower, compare them with the target values, adjust the absorbent flow rate or concentration according to the composition of the outlet exhaust gas, control the temperature and pressure inside the tower, replenish fresh absorbent in a timely manner, and discharge saturated absorbent.

[0024] Adsorption tower: The DCS system receives and processes the operating parameters of the inlet and outlet pipes of the adsorption tower, determines whether the current adsorption state meets the requirements, switches the adsorption tower periodically, regenerates the saturated adsorption tower, and adjusts the adsorption temperature and pressure to enhance the adsorption efficiency.

[0025] Optionally, the control parameters for real-time monitoring and control of the compressor pressurization and dryer dehydration of the separated ethylene in step S5 are achieved through the following methods:

[0026] Compressor boosting: The inlet and outlet pressure, temperature and flow of the compressor are obtained and compared with the preset values ​​to determine whether they meet the requirements. The DCS system automatically changes the motor speed or adjusts the bypass valve opening to stabilize the pressure output.

[0027] Dryer dehydration: The DCS system receives and processes the operating data of the dryer's temperature, humidity, and residence time, calculates the current drying efficiency, compares it with the target value, and dynamically adjusts the operating parameters according to the drying effect, changing the heating power, extending or shortening the drying time. When the humidity at the outlet exceeds the set threshold, the switching program is initiated, switching to the standby dryer and starting the regeneration process.

[0028] Optionally, in step S6, the parameter range of the pyrolysis reaction at each detection control point is calculated in the following way:

[0029] Step A1: Acquire real-time operating data of the pyrolysis process and configure a historical database to record time-series data of key parameters;

[0030] Step A2: Perform basic statistical analysis on the data of each detection control point, use time series analysis technology to observe the trend of parameter changes over time, identify any periodic patterns or long-term trends, explore the relationship between different parameters, and use correlation coefficients or other statistical indicators to quantify the strength of the relationship.

[0031] Step A3: Calculate the parameter range. Based on the analysis results in Step A2, set a reasonable range of operating parameters for each detection control.

[0032] Optionally, in step S7, important detection control points are selected for detection in the following manner:

[0033] Step B1: Assess the importance level of each detection and control point based on the key input variables such as ethylene yield, equipment safety operation risk, process control difficulty, and whether it belongs to closed-loop control;

[0034] Step B2: Based on the evaluation results, select the control points that play a key role in the pyrolysis process, form a list of key monitoring points, establish a dynamic monitoring strategy, set alarm thresholds and automatic adjustment logic for key detection points, and configure a trend prediction model.

[0035] A DCS control system for ethylene production by thermal cracking, employing the aforementioned DCS control method for ethylene production by thermal cracking, includes a feedstock pretreatment monitoring module, a cracking condition monitoring and adjustment module, a high-temperature gas cooling control module, a separation process monitoring and control module, an ethylene pressurization and dehydration control module, a historical data analysis parameter range setting module, and a key detection control point evaluation and monitoring module.

[0036] The raw material pretreatment monitoring module is used to pretreat the raw materials entering the cracking furnace and to monitor and control the quality and flow rate of the raw materials.

[0037] The pyrolysis condition monitoring and adjustment module is used to monitor and adjust the pyrolysis temperature, pressure, and the ratio of steam to feedstock.

[0038] The high-temperature gas cooling control module is used to control the cooling rate and final temperature of the pyrolyzed high-temperature gas.

[0039] The separation process monitoring and control module is used to monitor and control the separation process and impurity removal operation of the fractionation tower, absorption tower and adsorption tower in real time;

[0040] The ethylene booster dehydration control module is used to monitor and control the operating parameters of the compressor booster and dryer dehydration of the separated ethylene in real time.

[0041] The historical data analysis parameter range setting module is used to acquire historical data of each detection control point, observe parameter change trends, identify patterns, explore relationships based on time series analysis technology, and set reasonable operating parameter ranges for each detection control point.

[0042] The critical detection and control point assessment and monitoring module is used to assess the importance level of each detection and control point based on factors such as ethylene yield and equipment safety operation risks, screen out critical control points, establish dynamic monitoring strategies, set real-time alarm thresholds and automatic adjustment logic, and configure trend prediction models.

[0043] The beneficial effects of this invention are:

[0044] 1. In this invention, by real-time monitoring and adjustment of key parameters such as the quality, flow rate, cracking temperature, and pressure of the raw materials, the stability and consistency of the production process are ensured, thereby improving the yield and purity of ethylene. Precise control of cracking conditions (such as the ratio of steam to raw materials) and cooling rate can effectively reduce energy consumption and waste emissions. Through effective regulation of the separation process, resource utilization is further improved.

[0045] 2. In this invention, the DCS system can automatically detect abnormal situations and respond in a timely manner (such as adjusting the combustion load or issuing an alarm), which helps to prevent potential safety accidents, ensure the safe operation of equipment and the health of personnel. By using advanced analysis tools and technologies (such as time series analysis), the operating parameter range of each detection control point can be accurately calculated and finely adjusted accordingly, so as to achieve precise control over the entire production process.

[0046] 3. In this invention, the trend prediction model based on historical data can help identify the importance level of key detection and control points, set dynamic monitoring strategies and alarm thresholds, thereby identifying potential problems in advance, taking preventive measures, and reducing risks. The historical data collected by the system can not only be used to optimize current operating parameters, but also provide important basis for future process improvements. Through data analysis, enterprises can gain a deeper understanding of the process and make more scientific and reasonable decisions. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of a method flow of the present invention.

[0048] Figure 2 This is a schematic diagram of a system structure according to the present invention.

[0049] Figure 3 This invention provides a system monitoring UI interface. Detailed Implementation

[0050] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] like Figure 1 As shown, a DCS control method for producing ethylene by thermal cracking includes the following steps:

[0052] Step S1: Pre-treat the raw materials entering the cracking furnace, and monitor and control the quality and flow rate of the raw materials;

[0053] The composition and purity of raw materials are monitored in real time by an online analyzer, the flow rate of raw materials is measured by a mass flow meter, sensor data is collected and analyzed, and the valve opening and pump speed are automatically adjusted to control the feed rate and composition.

[0054] Step S2: The raw material is mixed with ultra-high temperature steam, and the pyrolysis temperature, pressure and the ratio of steam to raw material are monitored and adjusted;

[0055] Temperature monitoring and adjustment: Multiple temperature detection points are set in the pyrolysis furnace, and temperature thresholds are set. The DCS system detects the temperature at the detection points and automatically adjusts the combustion parameters or issues an alarm based on the detected temperature and temperature threshold.

[0056] Pressure monitoring and adjustment: The DCS system detects the outlet pressure of the cracking furnace and determines whether the pressure is within the pressure balance range. If the pressure is higher than the pressure balance range, the system will adjust the inlet valve or relief valve of the quench tower in conjunction with the pressure balance range. Conversely, the system will adjust the feed pump frequency or bypass valve.

[0057] Steam and raw material ratio monitoring and adjustment: Measure the mass flow rate of raw materials and steam respectively, calculate the actual water-carbon ratio, compare it with the set value, and if the ratio deviates from the set value, adjust the steam regulating valve or the raw material pump speed to compensate.

[0058] Step S3: Control the cooling rate and final temperature of the high-temperature gas after pyrolysis;

[0059] Temperature monitoring points are set at the inlet and outlet of the quench tower. The DCS system monitors the temperature of the cracked gas when it enters and the temperature change after quenching. It automatically adjusts the flow rate of the cooling medium to control the cooling rate. Increasing the flow rate of the cooling medium speeds up the cooling rate, and vice versa.

[0060] Step S4: Real-time monitoring and control of the separation process and impurity removal in the fractionation tower, absorption tower, and adsorption tower;

[0061] Fractionation column: Obtain the operating parameters of the fractionation column, compare and analyze them with preset values, adjust the heating or cooling amount according to the temperature changes at the top and bottom of the column, adjust the reflux flow rate to maintain the reflux ratio, control the feed rate and composition, and improve the fractionation efficiency.

[0062] Absorption tower: Continuously and in real time acquire the working parameters of the inlet and outlet status of the absorption tower, compare them with the target values, adjust the absorbent flow rate or concentration according to the composition of the outlet exhaust gas, control the temperature and pressure inside the tower, replenish fresh absorbent in a timely manner, and discharge saturated absorbent.

[0063] Adsorption tower: The DCS system receives and processes the operating parameters of the inlet and outlet pipes of the adsorption tower, determines whether the current adsorption state meets the requirements, switches the adsorption tower periodically, regenerates the saturated adsorption tower, and adjusts the adsorption temperature and pressure to enhance the adsorption efficiency.

[0064] Step S5: Real-time monitoring and control of the operating parameters for compressor pressurization and dryer dehydration of the separated ethylene;

[0065] Compressor boosting: The inlet and outlet pressure, temperature and flow of the compressor are obtained and compared with the preset values ​​to determine whether they meet the requirements. The DCS system automatically changes the motor speed or adjusts the bypass valve opening to stabilize the pressure output.

[0066] Dryer dehydration: The DCS system receives and processes the operating data of the dryer's temperature, humidity, and residence time, calculates the current drying efficiency, compares it with the target value, and dynamically adjusts the operating parameters according to the drying effect, changing the heating power, extending or shortening the drying time. When the humidity at the outlet exceeds the set threshold, the switching program is initiated, switching to the standby dryer and starting the regeneration process.

[0067] Step S6: Obtain historical data for each detection control point, and calculate the parameter range of the thermal decomposition reaction for each detection control point based on the historical data;

[0068] Step A1: Acquire real-time operating data of the pyrolysis process and configure a historical database to record time-series data of key parameters;

[0069] Step A2: Perform basic statistical analysis on the data of each detection control point, use time series analysis technology to observe the trend of parameter changes over time, identify any periodic patterns or long-term trends, explore the relationship between different parameters, and use correlation coefficients or other statistical indicators to quantify the strength of the relationship.

[0070] Step A3: Calculate the parameter range. Based on the analysis results in Step A2, set a reasonable range of operating parameters for each detection control.

[0071] Step S7: Select important detection control points for detection based on the parameter range of the pyrolysis reaction at each detection control point;

[0072] Step B1: Assess the importance level of each detection and control point based on the key input variables such as ethylene yield, equipment safety operation risk, process control difficulty, and whether it belongs to closed-loop control;

[0073] Step B2: Based on the evaluation results, select the control points that play a key role in the pyrolysis process, form a list of key monitoring points, establish a dynamic monitoring strategy, set alarm thresholds and automatic adjustment logic for key detection points, and configure a trend prediction model.

[0074] Based on the process flow diagram and DCS system structure of the ethylene cracking unit, list all monitoring and control points related to the thermal cracking reaction, such as: cracking furnace outlet temperature, feed flow rate, steam flow rate, water-to-carbon ratio, quench tower inlet / outlet temperature, fractionation tower reflux ratio, compressor inlet and outlet pressure, dryer outlet dew point, etc.

[0075] Using the historical database in the DCS system (such as PI Historian, OPC HDA server, or local SQL database), configure the following tasks: define the sampling period (e.g., once per minute), set the time window (e.g., the past 30 days, 90 days, or a specific production cycle), and extract the time series data (including timestamps and measurements) for each detection control point.

[0076] Use data analysis tools to clean and organize the raw data:

[0077] Remove outliers (such as maximum / minimum values ​​caused by sensor malfunction).

[0078] Fill in missing values ​​(using interpolation or filling with preceding and following values).

[0079] Normalize the data (if necessary).

[0080] Statistical analysis was performed on each detection control point to determine its typical operating range:

[0081] Calculate the mean and standard deviation, determine the maximum and minimum values, and calculate the 5% to 95th percentiles (to remove the effects of extreme fluctuations).

[0082] Use visual charts such as trend graphs and box plots to aid in judgment.

[0083] Based on the above statistical data, combined with process requirements and safe operating procedures, reasonable parameter control ranges are set for each detection control point, such as: temperature control range: 780°C ± 15°C, pressure control range: 0.25 MPa ± 0.05 MPa, and water-to-carbon ratio control range: 0.8 ~ 1.1 kg / kg.

[0084] The importance level of each detection control point is assessed based on the following factors:

[0085] The impact on ethylene yield (high → medium → low), the risk to safe equipment operation, the difficulty of process control (frequency of fluctuation), and whether it is a key input variable for closed-loop control.

[0086] Based on the assessment results, key control points that play a critical role in the pyrolysis process were selected, forming a "List of Key Monitoring Points," as shown in the table below:

[0087]

[0088] Configure the following settings for these critical detection and control points in the DCS system:

[0089] Real-time alarm threshold (alarm is triggered immediately if the threshold is exceeded), trend prediction model (optional), automatic adjustment logic (such as PID control).

[0090] Historical data is updated monthly / quarterly, and the parameter range is recalculated.

[0091] Verify the effectiveness of key detection control points, and adjust the list or parameter range if necessary.

[0092] Incorporate new batch production data into the analysis to continuously optimize control strategies.

[0093] A DCS control system for ethylene production by thermal cracking, employing the aforementioned DCS control method for ethylene production by thermal cracking, includes a feedstock pretreatment monitoring module, a cracking condition monitoring and adjustment module, a high-temperature gas cooling control module, a separation process monitoring and control module, an ethylene pressurization and dehydration control module, a historical data analysis parameter range setting module, and a key detection control point evaluation and monitoring module.

[0094] The raw material pretreatment monitoring module is used to pretreat the raw materials entering the cracking furnace and monitor and control the quality and flow rate of the raw materials. It monitors the composition and purity of the raw materials in real time through an online analyzer, measures the flow rate of the raw materials using a mass flow meter, and automatically adjusts the valve opening and pump speed to control the feed rate and composition.

[0095] The pyrolysis condition monitoring and adjustment module is used to monitor and adjust the pyrolysis temperature, pressure, and the ratio of steam to feedstock; it sets multiple temperature detection points in the pyrolysis furnace and sets temperature thresholds; it detects the outlet pressure of the pyrolysis furnace and determines whether it is within the equilibrium range; it measures the mass flow rates of feedstock and steam respectively, calculates the actual water-carbon ratio, and adjusts the steam regulating valve or feedstock pump speed to compensate for ratio deviations.

[0096] The high-temperature gas cooling control module is used to control the cooling rate and final temperature of the pyrolysis gas. By setting temperature monitoring points at the inlet and outlet of the quench tower, the module monitors the temperature of the pyrolysis gas when it enters and the temperature change after quenching, and automatically adjusts the flow rate of the cooling medium to control the cooling rate.

[0097] The separation process monitoring and control module is used to monitor and control the separation process and impurity removal operation of the fractionation tower, absorption tower and adsorption tower in real time; including adjusting the heating or cooling amount, reflux flow rate, absorbent flow rate or concentration, and periodically switching adsorption towers, so as to improve the working efficiency and separation effect of each tower.

[0098] The ethylene booster dehydration control module is used to monitor and control the operating parameters of the compressor booster and dryer dehydration of the separated ethylene in real time. By acquiring the working data of the compressor and dryer and comparing them with preset values, it automatically adjusts the motor speed, bypass valve opening, heating power, etc., to stabilize the output pressure and optimize the drying efficiency.

[0099] The historical data analysis parameter range setting module is used to acquire historical data of each detection control point, observe parameter change trends, identify patterns, explore relationships based on time series analysis technology, and set reasonable operating parameter ranges for each detection control point.

[0100] The critical detection and control point assessment and monitoring module is used to assess the importance level of each detection and control point based on factors such as ethylene yield and equipment safety operation risks, screen out critical control points, establish dynamic monitoring strategies, set real-time alarm thresholds and automatic adjustment logic, and configure trend prediction models.

[0101] This invention ensures the stability and consistency of the production process by real-time monitoring and adjustment of key parameters such as the quality, flow rate, cracking temperature, and pressure of the raw materials, thereby improving the yield and purity of ethylene. Precise control of cracking conditions (such as the ratio of steam to raw materials) and cooling rate can effectively reduce energy consumption and waste emissions. Through effective regulation of the separation process, resource utilization is further improved.

[0102] The DCS system can automatically detect abnormal situations and respond in a timely manner (such as adjusting the combustion load or issuing an alarm), which helps prevent potential safety accidents, ensure the safe operation of equipment and the health of personnel. By using advanced analysis tools and technologies (such as time series analysis), the operating parameter range of each detection control point can be accurately calculated and finely adjusted accordingly, so as to achieve precise control over the entire production process.

[0103] Trend prediction models built upon historical data can help identify the importance levels of key control points, set dynamic monitoring strategies and alarm thresholds, thereby proactively identifying potential problems, taking preventative measures, and reducing risks. The historical data collected by the system can not only be used to optimize current operating parameters but also provides crucial information for future process improvements. Through data analysis, enterprises can gain a deeper understanding of their processes, leading to more scientific and rational decision-making.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A DCS control method applied to thermal cracking for ethylene production, characterized in that, The method comprises the following steps: Step S1: Pretreatment of raw materials entering the cracking furnace, monitoring and controlling the quality and flow rate of the raw materials; Step S2: Mixing of the raw materials with ultra-high temperature steam, monitoring and adjusting the cracking temperature, pressure and the proportion of steam to raw materials; Step S3: Controlling the cooling rate and end point temperature of the high-temperature gas after cracking; Step S4: Real-time monitoring and regulation of the separation process and impurity removal of the fractionating column, the absorption column and the adsorption column; Step S5: Real-time monitoring and control of the control operation parameters of the compressor pressurization and the dryer dehydration of the separated ethylene; Step S6: Obtaining the historical data of each detection control point, and calculating the parameter range of the thermal cracking reaction of each detection control point according to the historical data; According to the process flow diagram of the ethylene cracking device and the structure of the DCS system, all the detection control points related to the thermal cracking reaction are listed, the data acquisition task is configured by using the historical database in the DCS system, the collected data is cleaned and arranged, and statistical analysis is performed on each detection control point to obtain its typical operating range, and a reasonable parameter control range is set for each detection control point in combination with the process requirements and the safety operation specification; Step S7: Selecting important detection control points for detection according to the parameter range of the thermal cracking reaction of each detection control point; The important detection control points are selected for detection by the following methods: Step B1: Evaluating the importance level of each detection control point according to the ethylene yield, the safety operation risk of the equipment, the process control difficulty and whether it is a key input variable of closed-loop control; Step B2: According to the evaluation results, screening out the control points which play a key role in the thermal cracking process, forming a list of key monitoring points, establishing a dynamic monitoring strategy, setting alarm thresholds and automatic adjustment logic for the key detection points, and configuring a trend prediction model; The historical data is updated, and the parameter range is recalculated, the key detection control points are verified, the list or the parameter range is adjusted, the new batch production data is included in the analysis, and the control strategy is optimized.

2. The DCS control method for thermal cracking for ethylene production according to claim 1, wherein, The quality and flow rate of the raw materials are monitored and controlled in step S1 by the following methods: The composition and purity of the raw materials are monitored in real time by an online analyzer, the flow rate of the raw materials is measured by a mass flow meter, sensor data is collected and analyzed, and the valve opening and pump speed are automatically adjusted to control the feed rate and composition.

3. The DCS control method for thermal cracking to produce ethylene according to claim 1, wherein, The cracking temperature, pressure and the proportion of steam to raw materials are monitored and adjusted in step S2 by the following methods: Temperature monitoring and adjustment: multiple temperature detection points are set in the cracking furnace, and temperature thresholds are set, the DCS system detects the temperature of the temperature detection points, and automatically adjusts the combustion load or sends an alarm according to the detected temperature and the temperature threshold; Pressure monitoring and adjustment: the DCS system detects the outlet pressure of the cracking furnace, and determines whether the pressure is within the pressure balance range, if the pressure is higher than the pressure balance range, the inlet valve or the relief valve of the quenching tower is adjusted, otherwise, the frequency of the feed pump or the bypass valve is adjusted; Steam to raw material ratio monitoring and adjustment: the mass flow rates of the raw materials and the steam are measured respectively, the actual steam to carbon ratio is calculated, compared with the set value, if the ratio deviates from the set value, the steam regulating valve or the raw material pump speed is adjusted for compensation.

4. The DCS control method for thermal cracking to produce ethylene according to claim 1, wherein, The step S3 controls the cooling rate and end temperature of the high-temperature gas after cracking by the following way: Temperature monitoring points are set at the inlet and outlet positions of the quenching tower, and the DCS system monitors the temperature when the cracking gas enters and the temperature change after quenching, automatically adjusts the flow of the cooling medium to control the cooling rate, and increases the flow of the cooling medium to speed up the cooling rate, and vice versa.

5. The DCS control method for thermal cracking to produce ethylene according to claim 1, wherein, The step S4 monitors and controls the separation process and impurity removal of the fractionating tower, the absorption tower and the adsorption tower in real time by the following way: Fractionating tower: Obtain the working parameters of the fractionating tower, compare and analyze with the preset values, adjust the heating or cooling amount according to the temperature change of the top and bottom of the tower, adjust the reflux flow to maintain the reflux ratio, control the feed rate and composition, and improve the fractionation efficiency; Absorption tower: Continuously obtain the working parameters of the absorption tower inlet and outlet, compare with the target value, adjust the flow or concentration of the absorbent according to the outlet exhaust composition, control the temperature and pressure in the tower, supplement fresh absorbent in time, and discharge the saturated absorbent; Adsorption tower: Obtain the working parameters of the inlet pipe and outlet pipe of the adsorption tower, and the DCS system receives and processes the working parameter information to judge whether the current adsorption state meets the demand, regularly switches the adsorption tower, regenerates the saturated adsorption tower, adjusts the adsorption temperature and pressure, and enhances the adsorption efficiency.

6. The DCS control method for thermal cracking to produce ethylene according to claim 1, wherein, The step S5 monitors and controls the control operation parameters of the ethylene separation compressor and the dryer in real time by the following way: Compressor pressurization: Obtain the inlet and outlet pressure, temperature and flow of the compressor, compare with the preset value to judge whether it meets the requirements, and the DCS system automatically changes the motor speed or adjusts the bypass valve opening to stabilize the pressure output; Dryer dehydration: Obtain the temperature, humidity and residence time working data of the dryer, and the DCS system receives and processes to calculate the current drying efficiency, compares with the target value, dynamically adjusts the working parameters according to the drying effect, changes the heating power, extends or shortens the drying time, and when the humidity at the outlet exceeds the set threshold, starts the switching program, switches to the standby dryer, and starts the regeneration process.

7. The DCS control method for thermal cracking to produce ethylene according to claim 1, wherein, The step S6 calculates the parameter range of the thermal cracking reaction of each detection control point by the following way: Step A1: Real-time acquisition of working data of thermal cracking process, configuration of historical database recording time series data of key parameters; Step A2: Perform basic statistical analysis on the data of each detection control point, use time series analysis technology to observe the trend of parameters over time, identify any periodic patterns or long-term trends, explore the relationship between different parameters, and use correlation coefficient or other statistical indicators to quantify the relationship strength; Step A3: Calculate the parameter range, set reasonable operation parameter range for each detection control point based on the analysis results in step A2.

8. A DCS control system for thermal cracking for ethylene production, which adopts the DCS control method for thermal cracking for ethylene production according to any one of claims 1 to 7, characterized by The system includes a raw material pretreatment monitoring module, a cracking condition monitoring and adjustment module, a high-temperature gas cooling control module, a separation process monitoring and control module, an ethylene pressurization and dehydration control module, a historical data analysis parameter range setting module, and a key detection control point evaluation monitoring module; A raw material pretreatment monitoring module is configured to pretreat the raw material entering the cracking furnace and monitor and control the quality and flow of the raw material; A cracking condition monitoring and adjusting module is configured to monitor and adjust the cracking temperature, pressure, and the ratio of steam to raw material; A high-temperature gas cooling control module is configured to control the cooling rate and end temperature of the high-temperature gas after cracking; A separation process monitoring and regulating module is configured to monitor and regulate the separation process and impurity removal operation of the fractionating column, the absorption column, and the adsorption column in real time; An ethylene booster dehydration control module is configured to monitor and control the operation parameters of the compressor boosting and the dryer dewatering of the separated ethylene in real time; A historical data analysis parameter range setting module is configured to obtain the historical data of each detection control point, observe the parameter change trend based on the time series analysis technology, identify the pattern, explore the relationship, and set a reasonable operation parameter range for each detection control point; A key detection control point evaluation monitoring module is configured to evaluate the importance level of each detection control point according to the ethylene yield, equipment safe operation risk, and other factors, screen out the key control points, establish a dynamic monitoring strategy, set a real-time alarm threshold and automatic adjusting logic, and configure a trend prediction model.

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