Butt-cut load adjusting system and method for automatic feeding and returning process of ethylene cracking furnace

Abstract

The invention relates to the technical field of petrochemical engineering, in particular to a split load adjusting system and method for the automatic feeding and returning process of an ethylene cracking furnace, and the system comprises a feeding load obtaining module which is used for obtaining the feeding load of each cracking furnace in real time, obtaining the residual feeding load of each cracking furnace according to the feeding load of each cracking furnace, and obtaining the residual feeding load of each cracking furnace; according to the feeding load and the residual feeding load of each cracking furnace, selecting two cracking furnaces meeting a bisection condition as a feeding cracking furnace and a returning cracking furnace respectively; the material feeding and returning process load adjustment control module is used for controlling the material returning cracking furnace to perform material returning according to the feeding load of the material returning cracking furnace, and controlling the feeding cracking furnace to perform feeding in the process of controlling the material returning cracking furnace to perform material returning; and the material feeding and returning execution module is used for feeding and returning materials according to the control instruction of the material feeding and returning process load adjustment control module. By applying the system, the load stability in the bisection process of the two ethylene cracking furnaces can be effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical industry, and in particular to a load shearing adjustment system and method for an automatic material feeding and withdrawing process of an ethylene cracking furnace. Background Art

[0002] Ethylene is an important basic raw material for petrochemical industry and one of the petrochemical products with the largest demand and production volume. Its output, scale and technical level indicate the development level of a country's petrochemical industry. The tubular cracking furnace is used for hydrocarbon cracking and is the core device for producing ethylene. It determines the production capacity, stable operation and overall energy consumption of the entire ethylene device. When hydrocarbons undergo steam cracking reaction in the radiation section of the tubular cracking furnace, coke will accumulate on the inner wall of the furnace tube due to secondary reactions such as polymerization and condensation in the radiation section, forming coke. When the temperature of the outer wall of the furnace tube in the radiation section or the outlet temperature of the quench boiler reaches the production limit or the pressure difference before and after the Venturi tube reaches the production limit due to coking, it will seriously affect the production of ethylene, and cause problems such as reduced ethylene yield, increased energy consumption, shortened furnace tube life, and even affect production safety.

[0003] Due to the coking characteristics of ethylene cracking furnaces, in actual application, it is necessary to frequently and intermittently perform operations such as feeding and withdrawing materials from the cracking furnace. At present, when the cracking furnaces in the ethylene industry are switched, usually due to insufficient operators, one cracking furnace needs to withdraw materials before the other one can be fed. This operation mode of feeding the other cracking furnace after one cracking furnace has withdrawn materials is likely to cause changes in the cracking gas flow rate, thereby causing production fluctuations in the downstream ethylene quenching, compression, and separation units, and thus causing a decrease in ethylene production. In addition, the withdrawal and feeding operations of the two cracking furnaces require two operators to operate independently, and control a single cracking furnace to complete the corresponding process. Not only is the labor intensity high and the efficiency low, but it also requires the coordination of two operators. Due to the uneven experience of the operators, in this long-term operation of the cracking furnace to feed or withdraw materials, it is very easy to have a mismatch between the withdrawal and feeding loads, which leads to system instability. If the operator further makes a mistake during the operation, it will greatly increase the instability of the system, thereby causing downstream production fluctuations, and thus affecting the production of ethylene.

[0004] Therefore, there is an urgent need for a load adjustment system and method for the automatic feeding and withdrawal process of an ethylene cracking furnace to ensure that the feeding and withdrawal operations of the two cracking furnaces are carried out simultaneously and the feeding and withdrawal loads remain consistent. Summary of the invention

[0005] In order to solve the problems in the prior art that there is a lack of a corresponding automatic feeding and discharging load adjustment system for the feeding and discharging of two ethylene cracking furnaces and load adjustment, and manual operation is used for feeding and discharging, which easily leads to the mismatch between the feeding amount and the discharging amount during the load adjustment of the feeding and discharging of the cracking furnace, resulting in production fluctuations in the downstream ethylene quenching, compression, and separation units, thus causing a decrease in ethylene production and low load switching efficiency, the present invention provides a system and method for adjusting the cut-over load during the automatic feeding and discharging process of an ethylene cracking furnace.

[0006] To achieve the above object, in a first aspect of the present invention, there is provided a system for adjusting the cut-over load during the automatic feeding and discharging process of an ethylene cracking furnace, the system comprising:

[0007] A feed load acquisition module, configured to acquire the feed load of each cracking furnace in real time, obtain the remaining feeding load of each cracking furnace according to the feed load of each cracking furnace, and select two cracking furnaces meeting the cut-over conditions as the feeding cracking furnace and the discharging cracking furnace respectively according to the feed load and the remaining feeding load of each cracking furnace;

[0008] A feeding and discharging process load adjustment control module, configured to control the discharging cracking furnace to discharge according to the feed load of the discharging cracking furnace, and simultaneously control the feeding cracking furnace to feed during the process of controlling the discharging cracking furnace to discharge;

[0009] A feeding and discharging execution module, configured to perform feeding and discharging according to the control instruction of the feeding and discharging process load adjustment control module.

[0010] Preferably, the controlling the discharging cracking furnace to discharge according to the feed load of the discharging cracking furnace specifically includes:

[0011] In the first discharging stage, discharging through the furnace main pipe of the discharging cracking furnace at a first discharging rate to a first discharging value and stabilizing for a set time;

[0012] In the second discharging stage, discharging through the furnace single pipes of the discharging cracking furnace at a second discharging rate to a second discharging value and stabilizing for a set time;

[0013] In the third discharging stage, discharging all the remaining materials to be discharged through the furnace single pipe control valve of the discharging cracking furnace at a valve position rate.

[0014] Preferably, the simultaneously controlling the feeding cracking furnace to feed during the process of controlling the discharging cracking furnace to discharge specifically includes:

[0015] When in the first discharging stage, feeding through the furnace single pipe control valve of the feeding cracking furnace at a valve position rate corresponding to the first discharging rate and stabilizing for a set time after the feeding ends;

[0016] During the second discharging stage, feeding is carried out through the single tubes in the furnace of the feeding cracking furnace at a feeding rate corresponding to the second discharging rate, and after the feeding is completed, a set time is maintained;

[0017] During the third feeding stage, feeding is carried out through the main tubes in the furnace of the feeding cracking furnace at a feeding rate corresponding to the valve position rate of the control valve of the single tube in the furnace of the discharging cracking furnace.

[0018] Preferably, the first discharging value is 60-80% of the feeding load of the discharging cracking furnace, the second discharging value is 20-45% of the feeding load of the discharging cracking furnace, and the set time is 0-20 min; the first discharging rate is 50-500 (kg / h) / min, the second discharging rate is 100-800 (kg / h) / min, and the valve position rate is 0.5-10% / min.

[0019] Preferably, the system further includes a pre-feeding and discharging state confirmation module for confirming the initial states of the discharging cracking furnace and the feeding cracking furnace before feeding and discharging;

[0020] The confirmation of the initial state of the discharging cracking furnace before feeding and discharging specifically includes:

[0021] Confirming the initial discharging parameters of the discharging cracking furnace, and when the initial discharging parameters are within the initial range, indicating that discharging can be carried out, and when the initial discharging parameters are not within the initial range, alarming one or more of the initial discharging parameters that are not within the initial range;

[0022] Confirming the initial feeding parameters of the feeding cracking furnace, and when the initial feeding parameters are within the initial range, indicating that feeding can be carried out, and when the initial feeding parameters are not within the initial range, alarming one or more of the initial feeding parameters that are not within the initial range.

[0023] Preferably, the initial discharging parameters include the sulfur injection amount, the cracking furnace outlet temperature, and the ultra-high pressure steam temperature; the initial feeding parameters include the quench oil temperature, the pressure after the Venturi tube, the single tube dilution steam flow in the furnace, the cracking furnace outlet temperature, and the ultra-high pressure steam temperature.

[0024] Preferably, the initial range of the sulfur injection amount of the material withdrawal cracking furnace is 2-5 kg / h, the initial range of the cracking furnace outlet temperature is 730-750 °C, and the initial range of the ultra-high pressure steam temperature is 505-520 °C; the initial range of the quenching oil temperature of the feedstock cracking furnace is 190-210 °C, the initial range of the pressure after the Venturi tube is 0.04-0.1 MPa, the initial range of the single-tube dilution steam flow rate in the furnace chamber is 3800-4500 kg / h, the initial range of the ultra-high pressure steam temperature is 480-500 °C, and the initial range of the cracking furnace outlet temperature is 720-740 °C.

[0025] Preferably, the system further includes a key parameter control module for controlling the key parameters of the material withdrawal cracking furnace and the feedstock cracking furnace; wherein, the key parameters include the single-tube dilution steam flow rate in the furnace chamber, the cracking furnace outlet temperature, and the oxygen content in the furnace chamber.

[0026] Preferably, the control of the key parameters of the material withdrawal cracking furnace and the feedstock cracking furnace specifically includes:

[0027] When the material withdrawal of the material withdrawal cracking furnace starts, control the single-tube dilution steam flow rate in the furnace chamber of the material withdrawal cracking furnace to increase to the first dilution steam value at the first set rate and remain constant; when the material withdrawal and feeding process ends, then control the single-tube dilution steam flow rate in the furnace chamber of the material withdrawal cracking furnace to adjust from the first dilution steam value to the second dilution steam value at the second set rate and remain constant;

[0028] When the feeding of the feedstock cracking furnace starts, control the single-tube dilution steam flow rate in the furnace chamber of the feedstock cracking furnace to decrease to the third dilution steam value at the third set rate and remain constant; when the material withdrawal and feeding process ends, then adjust the single-tube dilution steam flow rate in the furnace chamber of the feedstock cracking furnace to the single-tube dilution steam flow rate corresponding to the dilution ratio at the fourth set rate.

[0029] Preferably, the control of the key parameters of the material withdrawal cracking furnace and the feedstock cracking furnace specifically further includes:

[0030] During the charging and discharging process, control the oxygen content in the furnace chambers of the discharging cracking furnace and the charging cracking furnace within the first set oxygen content range. When the oxygen content in the furnace chamber of the discharging cracking furnace and / or the charging cracking furnace is lower than the lower limit value of the first set oxygen content range, open the damper of the corresponding cracking furnace by the first damper amplitude. After a preset time interval, if the oxygen content in the furnace chamber of the corresponding cracking furnace is still lower than the lower limit value of the first set oxygen content range, continue to open the damper of the corresponding cracking furnace by the first damper amplitude until the oxygen content in the furnace chamber of the corresponding cracking furnace is within the first set oxygen content range. When the oxygen content in the furnace chamber of the discharging cracking furnace and / or the charging cracking furnace is higher than the upper limit value of the first set oxygen content range, close the damper of the corresponding cracking furnace by the second damper amplitude. After a preset time interval, if the oxygen content in the furnace chamber of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, continue to close the damper of the corresponding cracking furnace by the second damper amplitude until the oxygen content in the furnace chamber of the corresponding cracking furnace is within the first set oxygen content range.

[0031] Preferably, the control of the key parameters of the discharging cracking furnace and the charging cracking furnace specifically further includes:

[0032] During the charging and discharging process, control the cracking furnace outlet temperature of the discharging cracking furnace and the charging cracking furnace within the first set temperature range. When the cracking furnace outlet temperature of the discharging cracking furnace and / or the charging cracking furnace is between the first furnace lower limit value and the second furnace lower limit value, control the fuel gas calorific value to increase by the first amplitude. After a preset time interval, if the cracking furnace outlet temperature of the corresponding cracking furnace is still between the first furnace lower limit value and the second furnace lower limit value, control the fuel gas calorific value to continue to increase by the first amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range. When the cracking furnace outlet temperature of the discharging cracking furnace and / or the charging cracking furnace is lower than the second furnace lower limit value, control the fuel gas calorific value to increase by the second amplitude. After a preset time interval, if the cracking furnace outlet temperature of the corresponding cracking furnace is still lower than the second furnace lower limit value, control the fuel gas calorific value to continue to increase by the second amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range.

[0033] When the cracking furnace outlet temperature of the material discharging cracking furnace and / or the material feeding cracking furnace is between the first furnace chamber upper limit value and the second furnace chamber upper limit value, control the calorific value of the fuel gas to decrease by a third amplitude. After an interval of a preset time, if the cracking furnace outlet temperature of the corresponding cracking furnace is still between the first furnace chamber upper limit value and the second furnace chamber upper limit value, control the calorific value of the fuel gas to continue to decrease by the third amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range; when the cracking furnace outlet temperature of the material discharging cracking furnace and / or the material feeding cracking furnace is higher than the second furnace chamber upper limit value, control the calorific value of the fuel gas to decrease by a fourth amplitude. After an interval of a preset time, if the cracking furnace outlet temperature of the corresponding cracking furnace is still higher than the second furnace chamber upper limit value, control the calorific value of the fuel gas to continue to decrease by the fourth amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range.

[0034] Preferably, the first set rate is 10 - 150 (kg / h) / min, the second set rate is 50 - 500 (kg / h) / min, the first dilution steam value is 3500 - 4500 kg / h, the second dilution steam value is 3800 - 5500 kg / h, the third dilution steam value is the furnace feeding target value * dilution ratio / the amount per single furnace tube, the dilution ratio is 0.3 - 0.55; the third set rate is (the initial dilution steam value - the third dilution steam value) * 1000 / (the furnace feeding target value / the amount per single furnace tube), the fourth set rate is 50 - 500 (kg / h) / min, the first set oxygen content range is 1 - 10%, the first air damper amplitude and the second air damper amplitude are 0.5 - 5%, the first set temperature range is 710 - 780 °C, the first furnace chamber lower limit value is the lower limit value of the first set temperature range, the second furnace chamber lower limit value is less than the first furnace chamber lower limit value and the difference between the two is 2 - 10 °C, the first furnace chamber upper limit value is the upper limit value of the first set temperature range, the second furnace chamber upper limit value is greater than the first furnace chamber upper limit value and the difference between the two is 2 - 10 °C, the first amplitude and the second amplitude are 0 - 0.4 MW, and the third amplitude and the fourth amplitude are 0.1 - 0.6 MW.

[0035] Preferably, the system further includes an operation navigation function module, which is used to, during the charging and discharging process, when the damper opening of the discharging cracking furnace and / or the charging cracking furnace is 0-25%, and the oxygen content in the furnace of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, prompt to check whether the on-site opening is consistent with the central control opening, and check whether all the sight holes and ignition holes are tightly closed; when the damper opening of the discharging cracking furnace and / or the charging cracking furnace is 70-100%, and the oxygen content in the furnace of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, stop adjusting the damper opening, prompt to check whether the on-site opening is consistent with the central control opening, and check whether all the sight holes and ignition holes are tightly closed; when the fuel gas pressure is lower than 0.05-0.1 MPa, prompt to close or open the auxiliary burner operation to maintain the fuel gas pressure within 0.1-0.3 MPa.

[0036] Preferably, the system further includes a key parameter monitoring and alarm module, which is used to monitor the key charging and discharging parameters during the charging and discharging stage, and alarm when the key charging and discharging parameters exceed the preset range.

[0037] Preferably, the key charging and discharging parameters include the cracking furnace outlet temperature, the carbon hydrocarbon flow rate and change rate of a single furnace tube, the total carbon hydrocarbon flow rate and change rate of the main pipe, the single pipe dilution steam flow rate, the fuel gas calorific value, the fuel gas pressure, the furnace O2 content, the CO content in the cracked gas, the pressure after the Venturi tube, the cracking furnace damper opening, the dilution steam ratio, the VHS steam drum liquid level, the VHS temperature, the temperature after the oil cooler, the cracking furnace cross-section temperature, the carbon hydrocarbon raw material pressure, and the valve position rate of the raw material control valve of a single furnace tube.

[0038] Preferably, the monitoring of the key charging and discharging parameters and the alarm when the key charging and discharging parameters exceed the preset range specifically include:

[0039] Alarm when the key charging and discharging parameters exceed the first preset range;

[0040] When the key charging and discharging parameters exceed the second preset range, adjust the key charging and discharging parameters that exceed the second preset range to the first preset range at a preset ratio based on their current values, and alarm;

[0041] Wherein, the upper limit value of the second preset range is greater than the upper limit value of the first preset range, the lower limit value of the second preset range is less than the lower limit value of the first preset range, and the preset ratio is ±0.1% - 10%.

[0042] Preferably, the system further includes an alarm optimization management module, which is used to automatically shield the instrument alarm of the feed system and turn on the prompt light of the feed / discharge alarm to turn red when the feed load of the cracking furnace is less than 65-75% of the design load; when the feed load is greater than 65-75% of the design load, automatically enable the instrument alarm of the feed system and turn on the prompt light of the feed / discharge alarm to turn green.

[0043] Preferably, the types of the instrument alarms of the feed system include total discharge alarm, liquid discharge flow alarm of the cracking furnace, gas discharge flow alarm of the cracking furnace, discharge interlock pressure alarm, DMDS force alarm, DMDS flow alarm, anti-coking steam pressure difference alarm, cracking furnace outlet temperature alarm, cross-section temperature alarm, quench oil flow alarm, Venturi inlet pressure alarm, cracking gas analysis indication alarm, cross-section flue gas oxygen content alarm, fuel heat load ratio alarm, low liquid raw material flow alarm of the furnace tube, and low gas raw material pressure alarm.

[0044] Preferably, the system further includes a deep learning function module, which is used to learn the control advantages and disadvantages of the key parameters of the discharge cracking furnace and the feeding cracking furnace based on empirical values and big data, and derive the optimal control values of the key parameters of the discharge cracking furnace and the feeding cracking furnace.

[0045] Preferably, the system further includes a control performance evaluation module, which is used to collect the loop information of the cracking furnace in real time, evaluate the control loop performance of the cracking furnace according to the loop information, and give an alarm when the control loop performance of the cracking furnace is abnormal.

[0046] To achieve the above object, the second aspect of the present invention provides a method for adjusting the cut load during the automatic feed / discharge process of an ethylene cracking furnace, which is applied to the above-mentioned system. The method includes:

[0047] Use the feed load acquisition module to obtain the feed load of each cracking furnace in real time, obtain the remaining feeding load of each cracking furnace according to the feed load of each cracking furnace, and select two cracking furnaces that meet the cut conditions as the feeding cracking furnace and the discharge cracking furnace respectively according to the feed load and the remaining feeding load of each cracking furnace;

[0048] Use the load adjustment control module during the feed / discharge process to control the discharge cracking furnace to discharge according to the feed load of the discharge cracking furnace, and during the process of controlling the discharge cracking furnace to discharge, simultaneously control the feeding cracking furnace to feed;

[0049] Use the feed / discharge execution module to perform feed / discharge according to the control instructions of the load adjustment control module during the feed / discharge process.

[0050] According to the above technical solution, based on the system and method, in the actual application process, the feed load acquisition module obtains the feed load of each cracking furnace in the cracking furnace group in real time, and obtains the remaining feeding load of each cracking furnace according to the feed load of each cracking furnace. Two cracking furnaces meeting the switching conditions can be quickly selected according to the feed load and the remaining feeding load of each cracking furnace, and used as the feeding cracking furnace and the discharging cracking furnace respectively. Further, through the load adjustment control module during the feeding and discharging process, according to the feed load of the discharging cracking furnace, the discharging cracking furnace is controlled to discharge materials, and during the process of controlling the discharging cracking furnace to discharge materials, the feeding cracking furnace is simultaneously controlled to feed materials, which can effectively ensure that the discharging amount and the feeding amount match during the switching process, thereby ensuring the stability of the load of the ethylene cracking furnace during the feeding and discharging process, and avoiding the decrease of ethylene production due to the unstable load during the feeding and discharging process. It has the advantages of high feeding and discharging accuracy, small fluctuation of key feeding and discharging parameters, and high load adjustment and switching efficiency. Brief Description of the Drawings

[0051] Figure 1 It is a flowchart of the switching load adjustment system for the automatic feeding and discharging process of the ethylene cracking furnace. Detailed Embodiments

[0052] The following will describe in detail the specific embodiments of the embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention.

[0053] The first aspect of the present invention provides a switching load adjustment system for the automatic feeding and discharging process of an ethylene cracking furnace, as Figure 1 shown. The switching load adjustment system for the automatic feeding and discharging process of the ethylene cracking furnace includes:

[0054] A feed load acquisition module, configured to obtain the feed load of each cracking furnace in real time, obtain the remaining feeding load of each cracking furnace according to the feed load of each cracking furnace, and select two cracking furnaces meeting the switching conditions as the feeding cracking furnace and the discharging cracking furnace respectively according to the feed load and the remaining feeding load of each cracking furnace;

[0055] A load adjustment control module during the feeding and discharging process, configured to control the discharging cracking furnace to discharge materials according to the feed load of the discharging cracking furnace, and simultaneously control the feeding cracking furnace to feed materials during the process of controlling the discharging cracking furnace to discharge materials;

[0056] A feeding and discharging execution module, configured to perform feeding and discharging according to the control instruction of the load adjustment control module during the feeding and discharging process.

[0057] In a specific embodiment, the feed load of the cracking furnace can be understood as the amount of material that can be withdrawn from the withdrawal cracking furnace, and the corresponding value is the target value of the furnace charge of the charging cracking furnace. Meeting the switching condition means that the remaining charging load of the selected charging cracking furnace is greater than the feed load of the withdrawal cracking furnace that needs to withdraw material.

[0058] According to the above technical solution, based on the system and method, in the actual application process, the feed load acquisition module obtains the feed load of each cracking furnace in the cracking furnace group in real time, and obtains the remaining charging load of each cracking furnace according to the feed load of each cracking furnace. Two cracking furnaces that meet the switching conditions can be quickly selected as the charging cracking furnace and the withdrawal cracking furnace respectively according to the feed load and the remaining charging load of each cracking furnace; and further through the load adjustment and control module for the charging and withdrawal process, according to the feed load of the withdrawal cracking furnace, control the withdrawal cracking furnace to withdraw material, and during the process of controlling the withdrawal cracking furnace to withdraw material, at the same time control the charging cracking furnace to charge material, which can effectively ensure the matching of the withdrawal amount and the charging amount during the switching process, thus ensuring the stability of the load of the ethylene cracking furnace during the charging and withdrawal process, and avoiding the decrease of ethylene production due to the instability of the load during the charging and withdrawal process. It has the advantages of high charging and withdrawal accuracy, small fluctuation of key charging and withdrawal parameters, and high load adjustment and switching efficiency.

[0059] In the switching load adjustment system for the automatic charging and withdrawal process of the ethylene cracking furnace described in the present invention, preferably, the system further includes a pre-charging and withdrawal state confirmation module for confirming the initial states of the withdrawal cracking furnace and the charging cracking furnace before charging and withdrawal;

[0060] The confirmation of the initial state of the withdrawal cracking furnace before charging and withdrawal specifically includes:

[0061] Confirm the initial withdrawal parameters of the withdrawal cracking furnace, and when the initial withdrawal parameters are within the initial range, indicate that withdrawal can be carried out. When the initial withdrawal parameters are not within the initial range, alarm one or more of the initial withdrawal parameters that are not within the initial range;

[0062] Confirm the initial charging parameters of the charging cracking furnace, and when the initial charging parameters are within the initial range, indicate that charging can be carried out. When the initial charging parameters are not within the initial range, alarm one or more of the initial charging parameters that are not within the initial range.

[0063] In a specific embodiment, the initial withdrawal parameters include sulfur injection amount, cracking furnace outlet temperature, and ultra-high pressure steam temperature; the initial charging parameters include quench oil temperature, pressure after the Venturi tube, single-tube dilution steam flow rate in the furnace, cracking furnace outlet temperature, and ultra-high pressure steam temperature.

[0064] In a more specific embodiment, the initial range of the sulfur injection amount of the discharging cracking furnace is 2 - 5 kg / h, the initial range of the cracking furnace outlet temperature is 730 - 750 °C, and the initial range of the ultra-high pressure steam temperature is 505 - 520 °C; the initial range of the quenching oil temperature of the feeding cracking furnace is 190 - 210 °C, the initial range of the pressure after the Venturi tube is 0.04 - 0.1 MPa, the initial range of the single-tube dilution steam flow rate in the furnace chamber is 3800 - 4500 kg / h, the initial range of the ultra-high pressure steam temperature is 480 - 500 °C, and the initial range of the cracking furnace outlet temperature is 720 - 740 °C.

[0065] In the present invention, before the feeding and discharging, by confirming the initial discharging parameters of the discharging cracking furnace and the initial feeding parameters of the feeding cracking furnace and maintaining them within the initial ranges, it is beneficial to ensure the accuracy of the feeding and discharging process and the stability of the load. Among them, the discharging cracking furnace and the feeding cracking furnace include DCS, CSL and the cracking furnace mode. Specifically, before the switching of the discharging cracking furnace and the feeding cracking furnace, DCS is in the "running" state, CSL is in the "running" state, and the cracking furnace is in the "full furnace" mode, so as to ensure that the cracking furnace can normally perform the feeding and discharging switching while enabling the load adjustment control module in the feeding and discharging process to better control key parameters such as the rate during the feeding and discharging process. In a specific embodiment, before the feeding and discharging switching, the low-low interlock of the cracking furnace gas and liquid phase feed pressure and the low-low interlock of the boiler feed water flow rate are switched to the bypass to better ensure the stability of the system load during the switching adjustment process.

[0066] In the load adjustment system for the automatic feeding and discharging process of the ethylene cracking furnace according to the present invention, preferably, the system further includes a control performance evaluation module, which is used to collect the loop information of the cracking furnace in real time before and during the feeding and discharging, evaluate the control loop performance of the cracking furnace according to the loop information, and give an alarm when the control loop performance of the cracking furnace is abnormal, so as to further effectively ensure the stability of the cracking furnace during the load adjustment process of the feeding and discharging and ensure safety.

[0067] In the load adjustment system for the automatic feeding and discharging process of the ethylene cracking furnace according to the present invention, preferably, controlling the discharging cracking furnace to discharge according to the feed load of the discharging cracking furnace specifically includes:

[0068] In the first discharging stage, discharging through the main furnace tube of the discharging cracking furnace at the first discharging rate to the first discharging value and stabilizing for a set time;

[0069] In the second discharging stage, discharging through the single furnace tube of the discharging cracking furnace at the second discharging rate to the second discharging value and stabilizing for a set time;

[0070] In the third material discharging stage, all the remaining materials to be discharged are discharged at a valve position rate through the furnace single-pipe control valve of the material discharging cracking furnace.

[0071] In a further preferred embodiment, during the process of controlling the material discharging cracking furnace to discharge materials, the feeding cracking furnace is simultaneously controlled to feed materials, which specifically includes:

[0072] When in the first material discharging stage, feeding is carried out at a valve position rate corresponding to the first material discharging rate through the furnace single-pipe control valve of the feeding cracking furnace, and a set time is stabilized after the feeding is completed;

[0073] When in the second material discharging stage, feeding is carried out at a feeding rate corresponding to the second material discharging rate through the furnace single-pipe of the feeding cracking furnace, and a set time is stabilized after the feeding is completed;

[0074] When in the third feeding stage, feeding is carried out at a feeding rate corresponding to the valve position rate of the furnace single-pipe control valve of the material discharging cracking furnace through the furnace main pipe of the feeding cracking furnace.

[0075] In a specific embodiment, the first material discharging value is 60-80% of the feed load of the material discharging cracking furnace, preferably 65-75%; the second material discharging value is 20-45% of the feed load of the material discharging cracking furnace, preferably 25-40%; the set time is 0-20 min, preferably 0-10 min; the first material discharging rate is 50-500 (kg / h) / min, preferably 100-300 (kg / h) / min; the second material discharging rate is 100-800 (kg / h) / min, preferably 150-350 (kg / h) / min; the valve position rate is 0.5-10% / min, preferably 1-3% / min.

[0076] In the present invention, by dividing the material discharging process into three stages, and in the first material discharging stage, using the furnace main pipe for material discharging, and in the second material discharging stage, using the single furnace pipes for material discharging, the accuracy during the material discharging process and the stability of the system load can be effectively ensured, and the efficiency can be improved, avoiding the influence of directly using the furnace main pipe on the material discharging precision and the influence of directly using the single furnace pipes on the material discharging efficiency. Further, in the third material discharging stage, all the remaining materials to be discharged are discharged at a valve position rate through the single furnace pipe control valve of the discharging cracking furnace, which can further effectively improve the accuracy of material discharging and ensure the stability of the cracking furnace during the load adjustment and switching. Further corresponding to the three stages of material discharging, in the first material discharging stage, the single furnace pipe control valve of the feeding cracking furnace is used to feed materials at a corresponding feeding rate, in the second material discharging stage, the single furnace pipes of the feeding cracking furnace are used to feed materials at a corresponding feeding rate, and in the third material discharging stage, the furnace main pipe of the feeding cracking furnace is used to feed materials at a corresponding feeding rate, which can further effectively ensure the matching of the discharged material quantity and the fed material quantity, thereby effectively ensuring the stability of the system cracking furnace load and improving the efficiency of load adjustment. In a preferred embodiment, when the feeding cracking furnace finishes feeding, the ratio of the dilution steam flow rate of the single furnace pipe of the feeding cracking furnace to the fed material quantity of the single furnace pipe is 0.2 - 0.6, preferably 0.35 - 0.5, so as to further ensure the stability of the system cracking furnace load. In a specific embodiment, the furnace main pipe of the cracking furnace usually includes at least one single furnace pipe.

[0077] In the load adjustment system for the ethylene cracking furnace's automatic feeding and discharging process according to the present invention, preferably, the system further includes a key parameter control module for controlling the key parameters of the discharging cracking furnace and the feeding cracking furnace; wherein, the key parameters include the dilution steam flow rate of the single furnace pipe, the cracking furnace outlet temperature, and the furnace oxygen content.

[0078] In a further preferred embodiment, the control of the key parameters of the discharging cracking furnace and the feeding cracking furnace specifically includes:

[0079] When the discharging cracking furnace starts to discharge materials, control the dilution steam flow rate of the single furnace pipe of the discharging cracking furnace to increase to a first dilution steam value at a first set rate and keep it constant; when the feeding and discharging process ends, then control the dilution steam flow rate of the single furnace pipe of the discharging cracking furnace to be adjusted from the first dilution steam value to a second dilution steam value at a second set rate and keep it constant;

[0080] When the feeding cracking furnace starts to feed materials, control the dilution steam flow rate of the single furnace pipe of the feeding cracking furnace to decrease to a third dilution steam value at a third set rate and keep it constant; when the feeding and discharging process ends, then adjust the dilution steam flow rate of the single furnace pipe of the feeding cracking furnace to the dilution steam flow rate of the single furnace pipe corresponding to the dilution ratio at a fourth set rate.

[0081] In a further preferred embodiment, the control of the key parameters of the discharging cracking furnace and the feeding cracking furnace specifically further includes:

[0082] During the discharging and feeding process, control the oxygen content in the furnace chambers of the discharging cracking furnace and the feeding cracking furnace within a first set oxygen content range. When the oxygen content in the furnace chamber of the discharging cracking furnace and / or the feeding cracking furnace is lower than the lower limit value of the first set oxygen content range, open the air damper of the corresponding cracking furnace by a first air damper amplitude. After a preset time interval, if the oxygen content in the furnace chamber of the corresponding cracking furnace is still lower than the lower limit value of the first set oxygen content range, continue to open the air damper of the corresponding cracking furnace by the first air damper amplitude until the oxygen content in the furnace chamber of the corresponding cracking furnace is within the first set oxygen content range; when the oxygen content in the furnace chamber of the discharging cracking furnace and / or the feeding cracking furnace is higher than the upper limit value of the first set oxygen content range, close the air damper of the corresponding cracking furnace by a second air damper amplitude. After a preset time interval, if the oxygen content in the furnace chamber of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, continue to close the air damper of the corresponding cracking furnace by the second air damper amplitude until the oxygen content in the furnace chamber of the corresponding cracking furnace is within the first set oxygen content range.

[0083] In a further preferred embodiment, the control of the key parameters of the discharging cracking furnace and the feeding cracking furnace specifically further includes:

[0084] During the discharging and feeding process, control the cracking furnace outlet temperature of the discharging cracking furnace and the feeding cracking furnace within a first set temperature range. When the cracking furnace outlet temperature of the discharging cracking furnace and / or the feeding cracking furnace is between the first furnace lower limit value and the second furnace lower limit value, control the fuel gas calorific value to increase by a first amplitude. After a preset time interval, if the cracking furnace outlet temperature of the corresponding cracking furnace is still between the first furnace lower limit value and the second furnace lower limit value, control the fuel gas calorific value to continue to increase by the first amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range; when the cracking furnace outlet temperature of the discharging cracking furnace and / or the feeding cracking furnace is lower than the second furnace lower limit value, control the fuel gas calorific value to increase by a second amplitude. After a preset time interval, if the cracking furnace outlet temperature of the corresponding cracking furnace is still lower than the second furnace lower limit value, control the fuel gas calorific value to continue to increase by the second amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range;

[0085] When the cracking furnace outlet temperature of the material withdrawal cracking furnace and / or the feedstock cracking furnace is between the first furnace upper limit value and the second furnace upper limit value, control the calorific value of the fuel gas to decrease by the third amplitude. After an interval of a preset time, if the cracking furnace outlet temperature of the corresponding cracking furnace is still between the first furnace upper limit value and the second furnace upper limit value, control the calorific value of the fuel gas to continue to decrease by the third amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range; when the cracking furnace outlet temperature of the material withdrawal cracking furnace and / or the feedstock cracking furnace is higher than the second furnace upper limit value, control the calorific value of the fuel gas to decrease by the fourth amplitude. After an interval of a preset time, if the cracking furnace outlet temperature of the corresponding cracking furnace is still higher than the second furnace upper limit value, control the calorific value of the fuel gas to continue to decrease by the fourth amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range.

[0086] In a specific embodiment, the first set rate is 10 - 150 (kg / h) / min, the second set rate is 50 - 500 (kg / h) / min, the first dilution steam value is 3500 - 4500 kg / h, the second dilution steam value is 3800 - 5500 kg / h, the third dilution steam value is the furnace feed target value * dilution ratio / furnace single tube amount, and the dilution ratio is 0.3 - 0.55; the third set rate is (initial dilution steam value - third dilution steam value) * 1000 / (furnace feed target value / furnace single tube amount), the fourth set rate is 50 - 500 (kg / h) / min, the first set oxygen content range is 1 - 10%, the first damper amplitude and the second damper amplitude are 0.5 - 5%, the first set temperature range is 710 - 780 °C, the first furnace lower limit value is the lower limit value of the first set temperature range, the second furnace lower limit value is less than the first furnace lower limit value and the difference between the two is 2 - 10 °C, the first furnace upper limit value is the upper limit value of the first set temperature range, the second furnace upper limit value is greater than the first furnace upper limit value and the difference between the two is 2 - 10 °C, the first amplitude and the second amplitude are 0 - 0.4 MW, and the third amplitude and the fourth amplitude are 0.1 - 0.6 MW.

[0087] In the present invention, by further designing a key parameter control module for controlling the single tube dilution steam flow rate, cracking furnace outlet temperature, and furnace oxygen content of the material withdrawal cracking furnace and the feedstock cracking furnace during the feed and withdrawal process, the fluctuations of the key parameters of the cracking furnace during feed and withdrawal can be effectively reduced, thereby greatly improving the stability of the system cracking furnace during the load adjustment and switching process.

[0088] In the load adjustment system for the cut-over process of the ethylene cracking furnace in the present invention, preferably, the system further includes an operation navigation function module, which is used to, during the charging and discharging process, when the damper opening of the discharging cracking furnace and / or the charging cracking furnace is 0-25%, and the oxygen content in the furnace of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, prompt to check whether the on-site opening is consistent with the central control opening, and check whether all the viewing holes and ignition holes are tightly closed; when the damper opening of the discharging cracking furnace and / or the charging cracking furnace is 70-100%, and the oxygen content in the furnace of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, stop adjusting the damper opening, prompt to check whether the on-site opening is consistent with the central control opening, and check whether all the viewing holes and ignition holes are tightly closed; when the fuel gas pressure is lower than 0.05-0.1 MPa, prompt to close or open the operation of the auxiliary burner to maintain the fuel gas pressure within 0.1-0.3 MPa. It can further effectively ensure the stability of the load during the cut-over process of the cracking furnace and ensure the safety of the system.

[0089] In the load adjustment system for the cut-over process of the ethylene cracking furnace in the present invention, preferably, the system further includes a deep learning function module, which is used to learn the control advantages and disadvantages of the key parameters of the discharging cracking furnace and the charging cracking furnace based on empirical values and big data, and derive the optimal control values of the key parameters of the discharging cracking furnace and the charging cracking furnace. Thus, by further optimizing the control advantages and disadvantages of the key parameters, the stability of the discharging cracking furnace and the charging cracking furnace during the charging and discharging process can be improved, and further the stability during the load switching adjustment process of the cracking furnace can be improved.

[0090] In the load adjustment system for the cut-over process of the ethylene cracking furnace in the present invention, preferably, the system further includes a key parameter monitoring and alarm module, which is used to monitor the key parameters of the charging and discharging during the charging and discharging stage, and alarm when the key parameters of the charging and discharging exceed the preset range.

[0091] In a preferred embodiment, the key parameters of the charging and discharging include the cracking furnace outlet temperature, the carbon hydrocarbon flow rate and change rate of a single furnace tube, the total carbon hydrocarbon flow rate and change rate of the main pipe, the single tube dilution steam flow rate, the fuel gas calorific value, the fuel gas pressure, the furnace O2 content, the CO content in the cracked gas, the pressure after the venturi tube, the cracking furnace damper opening, the dilution steam ratio, the VHS steam drum liquid level, the VHS temperature, the temperature after the oil cooler, the cracking furnace cross-section temperature, the carbon hydrocarbon raw material pressure, and the valve position rate of the raw material control valve of a single furnace tube.

[0092] In a further preferred embodiment, monitoring the key parameters of the charging and discharging and alarming when the key parameters of the charging and discharging exceed the preset range specifically includes:

[0093] Alarm when the key parameters of the charging and discharging exceed the first preset range;

[0094] When the key feed / discharge parameter exceeds the second preset range, the key feed / discharge parameter that exceeds the second preset range is adjusted to within the first preset range at a preset ratio based on its current value, and an alarm is given.

[0095] Wherein, the upper limit value of the second preset range is greater than the upper limit value of the first preset range, the lower limit value of the second preset range is less than the lower limit value of the first preset range, and the preset ratio is ±0.1% - 10%.

[0096] In the present invention, by further designing the key parameter monitoring and alarm module, the stability and safety of the feed withdrawal cracking furnace and the feedstock charging cracking furnace during the feed / discharge process can be further ensured. Specifically, taking the temperature after the oil cooler among the key feed / discharge parameters as an example, the first preset range is 200 - 208 °C, then the second preset range is 195 - 212 °C. When the key parameter monitoring and alarm module monitors that the temperature after the oil cooler is 199 °C, an alarm is given; when the key parameter monitoring and alarm module monitors that the temperature after the oil cooler is 194 °C, the temperature after the oil cooler is expanded to within the first preset range at a ratio of 0.1% - 10% based on 194 °C, thereby improving the safety of the system during the entire feed / discharge load switching process.

[0097] Furthermore, the key parameter monitoring and alarm module can set the alarm display status according to the priority, and the alarm sound and light signals should be easily distinguishable. For example, when the temperature after the oil cooler exceeds the first preset range, a first-level alarm is adopted; when the temperature after the oil cooler exceeds the second preset range, a second-level alarm is given. Specifically, the first-level alarm uses yellow background with black characters, flashing, and low-frequency sound; the second-level alarm uses orange background with black characters, flashing, and medium-frequency sound. Moreover, the boundary values of the first preset range and the second preset range should not coincide with the instrument range of the alarm device of the key parameter monitoring and alarm module, and should be set within the range of 10% - 90% of the maximum instrument range.

[0098] In the load adjustment system for the automatic feed / discharge process of the ethylene cracking furnace described in the present invention, preferably, the system further includes an alarm optimization management module, which is used to automatically shield the alarm of the feed system instrument when the feed load of the cracking furnace is less than 65 - 75% of the design load, and the prompt light for enabling the feed / discharge alarm turns red; when the feed load is greater than 65 - 75% of the design load, the alarm of the feed system instrument is automatically enabled, and the prompt light for enabling the feed / discharge alarm turns green.

[0099] In a preferred embodiment, the types of instrument alarms of the feeding system include total discharge alarm, liquid discharge flow alarm of the cracking furnace, gas discharge flow alarm of the cracking furnace, discharge interlock pressure alarm, DMDS force alarm, DMDS flow alarm, anti-coking steam differential pressure alarm, cracking furnace outlet temperature alarm, cross-section temperature alarm, quench oil flow alarm, Venturi inlet pressure alarm, cracking gas analysis indication alarm, cross-section flue gas oxygen content alarm, fuel heat load ratio alarm, low liquid raw material flow alarm of the furnace tube, and low gas raw material pressure alarm.

[0100] In the present invention, by further designing an alarm optimization management module, it is possible to effectively avoid frequent false alarms during the feeding and discharging processes of the feeding cracking furnace and the discharging cracking furnace, which may affect the efficiency of load adjustment and switching.

[0101] In the load adjustment system for the automatic feeding and discharging process of the ethylene cracking furnace described in the present invention, preferably, the system further includes a parameter setting module for setting the rate parameters and key parameters of the discharging cracking furnace and the feeding cracking furnace, so that in actual production, the operator can set each rate parameter, key parameter, and the allowable deviation or upper and lower limit range values of each parameter according to the actual production needs.

[0102] In the load adjustment system for the automatic feeding and discharging process of the ethylene cracking furnace described in the present invention, preferably, the system further includes an inspection module after feeding and discharging switching for inspecting the states of the discharging cracking furnace and the feeding cracking furnace after the feeding and discharging are completed, so as to further ensure production safety.

[0103] Specifically, after the feeding and discharging switching is completed, the system gives an operation prompt through the operation navigation function module. The inspection of the discharging cracking furnace includes: closing 1 to 2 burners in each group of main burners to control the calorific value of the fuel gas to keep the outlet temperature of the cracking furnace stable after discharging; turning the quench oil regulating valve of the oil cooler to the "manual" control state; closing the quench oil regulating valve of the oil cooler and the on-site electric main valve, opening the quench oil return line of the oil cooler, and returning the quench oil to the quench oil tower; adjusting the damper opening to control the oxygen content in the furnace chamber within the range of 2 to 10%.

[0104] After the switching of feeding and discharging is completed, the system gives operation prompts through the operation navigation function module. The inspection of the feeding cracking furnace includes: the fuel gas calorific value is set to the "cascade" control state; the single-tube gas-phase or / and liquid-phase feeding flow rate in the furnace is set to the "cascade" control state; the furnace negative pressure is in the range of -40 to -205 Pa; the oxygen content in the furnace is in the range of 1.5% to 5%; confirm that there is no leakage at all flanges and connection parts outside the furnace; confirm that the on-line analyzer of the cracking furnace furnace is put into use; the VHS temperature is controlled at about 519 °C; confirm that the Venturi pressure deviation is less than 25 kPa; confirm that the high-high furnace negative pressure, high-high ultra-high pressure temperature, low-low drum liquid level, and low-low fuel gas (bottom, pilot line) pressure interlocks are in normal states.

[0105] In a specific embodiment, the system for adjusting the cutting load during the automatic feeding and discharging process of the ethylene cracking furnace according to the present invention is composed of a human-machine interface and a program control system, so as to realize on-line control through a combination of field distributed control system (DCS) configuration and host computer server programming. At the same time, in order to realize the automatic execution of the automatic feeding and discharging process of the ethylene cracking furnace, an independent server needs to be deployed on the industrial control network. The program for the feeding and discharging switching process of the ethylene cracking furnace performs data interaction through the OPC server OPC DA interface of Emerson DCS to obtain the numerical values or states of relevant parameters. In order to ensure the safe operation of the DCS system, an industrial firewall is added between the system server and the communication interface. By configuring corresponding rule policies, deep isolation and protection of the DCS control system are realized, the virus transmission path is cut off, and the normal, safe and stable operation of the device DCS production control system is ensured. The industrial firewall incorporates private communication protocols of multiple mainstream automation product manufacturers, and can realize seamless access to various mainstream automation products such as Honeywell DCS, Yokogawa DCS, Emerson DCS systems, as well as servers or databases such as OPC SERVER, IP21 / PHD / PI.

[0106] Among them, the interface design of the human-machine interaction interface has function buttons such as "Settings" for parameters, "Confirmation" of the cracking furnace status, "Run" the program, "Pause" during operation, "Resume" during operation, "Stop" during operation, and "Alarm" for parameters to achieve human-machine interaction functions. Specifically, during actual use, clicking the "Parameter Settings" button can manually set the control thresholds of the key parameters of the program and the upper and lower preset values of the key parameters, etc.; clicking the "Cracking Furnace Status Confirmation" button completes the status confirmation work before the feed and discharge switching, and the interface jumps to the feed and discharge operation interface, otherwise the feed and discharge switching program cannot run; clicking the "Program Run" button, the feed and discharge switching program starts to run; clicking "Pause", the system stops the next step of the program, and the control values of each parameter of the feed and discharge switching program remain the current values. Clicking "Resume", the program will continue according to the current execution steps; manually clicking "Stop", the system stops the automatic feed and discharge switching program of the cracking furnace and switches to manual operation; clicking the "Alarm Button", the human-machine interaction interface switches to the alarm interface, where the system alarm situation can be viewed in detail, and at the same time, it is possible to select whether to enable the alarm shielding function during the feed and discharge load adjustment and switching process according to needs.

[0107] Furthermore, the functions of the human-machine interaction interface also include system operation status display, system operation buttons, key parameter trend charts, and system alarm prompt information. Among them, for the function buttons such as "Run", "Stop", "Pause", "Resume", and "Parameter Settings" designed on the human-machine interaction interface, during the operation of the system, users can execute the above function buttons at any time according to the actual operation conditions of the ethylene plant and the compressor.

[0108] The second aspect of the present invention provides a method for adjusting the cut load during the automatic feed and discharge process of an ethylene cracking furnace, which is applied to the above-mentioned system. The method includes:

[0109] Using the feed load acquisition module to continuously acquire the feed load of each cracking furnace in real time, and obtaining the remaining feeding load of each cracking furnace based on the feed load of each cracking furnace. Select two cracking furnaces that meet the cut conditions based on the feed load and remaining feeding load of each cracking furnace as the feeding cracking furnace and the discharging cracking furnace respectively;

[0110] Using the load adjustment control module for the feed and discharge process to control the discharging cracking furnace to discharge according to the feed load of the discharging cracking furnace, and during the process of controlling the discharging cracking furnace to discharge, simultaneously control the feeding cracking furnace to feed;

[0111] Using the feed and discharge execution module to perform feed and discharge according to the control instructions of the load adjustment control module for the feed and discharge process.

[0112] In the actual application process of the method of the present invention, by using the feed load acquisition module and the load adjustment control module for the feed and discharge process in cooperation, the load stability and load switching efficiency of the cracking furnace during the feed and discharge process can be effectively improved.

[0113] The present invention will be described in detail below through embodiments, but the protection scope of the present invention is not limited thereto.

[0114] Embodiment 1

[0115] Based on 6 ethylene cracking furnaces with a production capacity of 140,000 tons / year, the counter-cut load adjustment system for the automatic charging and discharging process of the ethylene cracking furnace as shown in the present invention is implemented. Specifically, the system includes: Figure 1 As shown, the counter-cut load adjustment system for the automatic charging and discharging process of the ethylene cracking furnace is implemented. Specifically, the system includes:

[0116] A feed load acquisition module, configured to acquire the feed load of each cracking furnace in real time, obtain the remaining feeding load of each cracking furnace according to the feed load of each cracking furnace, and select two cracking furnaces that meet the counter-cut conditions as the feeding cracking furnace and the discharging cracking furnace respectively according to the feed load and the remaining feeding load of each cracking furnace;

[0117] A load adjustment control module for the charging and discharging process, configured to control the discharging cracking furnace to discharge according to the feed load of the discharging cracking furnace, and simultaneously control the feeding cracking furnace to feed during the process of controlling the discharging cracking furnace to discharge;

[0118] A charging and discharging execution module, configured to perform charging and discharging according to the control instructions of the load adjustment control module for the charging and discharging process;

[0119] Specifically, the system further includes a state confirmation module before charging and discharging, configured to confirm the initial states of the discharging cracking furnace and the feeding cracking furnace before charging and discharging;

[0120] The confirmation of the initial state of the discharging cracking furnace before charging and discharging specifically includes:

[0121] Confirm the initial discharging parameters of the discharging cracking furnace, and when the initial discharging parameters are within the initial range, indicate that discharging can be performed. When the initial discharging parameters are not within the initial range, alarm for one or more of the initial discharging parameters that are not within the initial range;

[0122] Confirm the initial feeding parameters of the feeding cracking furnace, and when the initial feeding parameters are within the initial range, indicate that feeding can be performed. When the initial feeding parameters are not within the initial range, alarm for one or more of the initial feeding parameters that are not within the initial range;

[0123] The initial discharging parameters include sulfur injection amount, cracking furnace outlet temperature, and ultra-high pressure steam temperature; the initial feeding parameters include quench oil temperature, pressure after the venturi tube, single-tube dilution steam flow rate in the furnace, cracking furnace outlet temperature, and ultra-high pressure steam temperature;

[0124] The initial range of the sulfur injection amount of the feedstock withdrawal cracking furnace is 2 - 5 kg / h, the initial range of the cracking furnace outlet temperature is 730 - 750 °C, and the initial range of the ultra-high pressure steam temperature is 505 - 520 °C; the initial range of the quenching oil temperature of the feedstock charging cracking furnace is 190 - 210 °C, the initial range of the pressure after the Venturi tube is 0.04 - 0.1 MPa, the initial range of the single-tube dilution steam flow rate in the furnace chamber is 3800 - 4500 kg / h, the initial range of the ultra-high pressure steam temperature is 480 - 500 °C, and the initial range of the cracking furnace outlet temperature is 720 - 740 °C;

[0125] Controlling the feedstock withdrawal cracking furnace to withdraw the feedstock according to the feedstock load of the feedstock withdrawal cracking furnace specifically includes:

[0126] In the first feedstock withdrawal stage, withdraw the feedstock to the first withdrawal value at the first withdrawal rate through the main furnace tube of the feedstock withdrawal cracking furnace and stabilize for the set time;

[0127] In the second feedstock withdrawal stage, withdraw the feedstock to the second withdrawal value at the second withdrawal rate through the single furnace tube of the feedstock withdrawal cracking furnace and stabilize for the set time;

[0128] In the third feedstock withdrawal stage, withdraw all the remaining feedstock to be withdrawn at the valve position rate through the single furnace tube control valve of the feedstock withdrawal cracking furnace;

[0129] During the process of controlling the feedstock withdrawal cracking furnace to withdraw the feedstock, simultaneously control the feedstock charging cracking furnace to charge the feedstock, specifically including:

[0130] When in the first feedstock withdrawal stage, charge the feedstock at the valve position rate corresponding to the first withdrawal rate through the single furnace tube control valve of the feedstock charging cracking furnace and stabilize for the set time after the charging is completed;

[0131] When in the second feedstock withdrawal stage, charge the feedstock at the charging rate corresponding to the second withdrawal rate through the single furnace tube of the feedstock charging cracking furnace and stabilize for the set time after the charging is completed;

[0132] When in the third charging stage, charge the feedstock at the charging rate corresponding to the valve position rate of the single furnace tube control valve of the feedstock withdrawal cracking furnace through the main furnace tube of the feedstock charging cracking furnace;

[0133] The first withdrawal value is 60 - 80% of the feedstock load of the feedstock withdrawal cracking furnace, the second withdrawal value is 20 - 45% of the feedstock load of the feedstock withdrawal cracking furnace, and the set time is 0 - 20 min; the first withdrawal rate is 50 - 500 (kg / h) / min, the second withdrawal rate is 100 - 800 (kg / h) / min, and the valve position rate is 0.5 - 10% / min;

[0134] Before the feedstock withdrawal and feeding of the cracking furnace, the DCS is in the "running" state, the CSL is in the "running" state, and the cracking furnace is in the "full furnace" mode.

[0135] The system also includes a control performance evaluation module, which is used to collect the loop information of the cracking furnace in real time, evaluate the control loop performance of the cracking furnace according to the loop information, and give an alarm when the control loop performance of the cracking furnace is abnormal.

[0136] In the actual application process, taking naphtha as the feedstock type for feedstock withdrawal and feeding as an example, first, the feedstock load acquisition module obtains the feedstock load of cracking furnaces No. 1-6 in real time, and obtains the remaining feeding load of each cracking furnace according to the feedstock load of each cracking furnace. Cracking furnace No. 1 is selected as the cracking furnace for feedstock withdrawal, and cracking furnace No. 3 with a remaining feeding load greater than 31016 kg / h is selected as the feeding cracking furnace according to the feedstock load of cracking furnace No. 1 being 31016 kg / h. Then, the initial feedstock withdrawal parameters of the feedstock withdrawal cracking furnace and the initial feeding parameters of the feeding cracking furnace are confirmed respectively. Specifically, the sulfur injection amount of the feedstock withdrawal cracking furnace is 3 kg / h, the cracking furnace outlet temperature is 740 °C, the ultra-high pressure steam temperature is 510 °C, the quenching oil temperature of the feeding cracking furnace is 200 °C, the pressure after the venturi tube is 0.09 MPa, the cracking furnace outlet temperature is 730 °C, the ultra-high pressure steam temperature is 490 °C, and the single-tube dilution steam flow rate in the furnace is 4200 kg / h. And it is confirmed by the control performance evaluation module that the control loops of each cracking furnace are normal. Then, the feedstock withdrawal and feeding process starts. Specifically, in the first feedstock withdrawal stage, the feedstock is withdrawn from the main furnace tube of the feedstock withdrawal cracking furnace at a rate of 200 kg / h until 70% of the feedstock load of the feedstock withdrawal cracking furnace is reached and stabilized for 2 minutes; in the second feedstock withdrawal stage, the feedstock is withdrawn from the single tube in the furnace of the feedstock withdrawal cracking furnace at a rate of 250 kg / h until 30% of the feedstock load of the feedstock withdrawal cracking furnace is reached and stabilized for 2 minutes; in the third feedstock withdrawal stage, the remaining feedstock to be withdrawn is all withdrawn from the control valve of the single tube in the furnace of the feedstock withdrawal cracking furnace at a rate of 2% / min. At the same time, during the feedstock withdrawal and feeding process load adjustment control module, in the first feedstock withdrawal stage, when the feedstock withdrawal rate of the main furnace tube of the feedstock withdrawal cracking furnace is 200 kg / h, the control valve of the single tube in the furnace of cracking furnace No. 3 is controlled to feed at a valve position rate corresponding to the first feedstock withdrawal rate, and it is stabilized for 2 minutes after the feeding is completed. In the second feedstock withdrawal stage, when the feedstock withdrawal rate of the single tube in the furnace of the feedstock withdrawal cracking furnace is 250 kg / h, the single tube in the furnace of cracking furnace No. 3 is controlled to feed at a feeding rate corresponding to the second feedstock withdrawal rate, and it is stabilized for 2 minutes after the feeding is completed; in the third feedstock withdrawal stage, the main furnace tube of cracking furnace No. 3 is controlled to feed at a feeding rate corresponding to the valve position rate of the control valve of the single tube in the furnace of the feedstock withdrawal cracking furnace until the feedstock withdrawal and feeding switching process is completed.

[0137] After detection, by using the counter-cut load adjustment system for the automatic feeding and discharging process of the ethylene cracking furnace described in the present invention, the synchronous progress of the feeding and discharging process is realized. Moreover, during the entire load adjustment process of feeding and discharging, the difference between the discharging amount of the discharging cracking furnace and the feeding amount of the feeding cracking furnace never exceeds 800 kg / h, having the advantages of high feeding and discharging accuracy, high switching efficiency of counter-cut load adjustment of the cracking furnace, and high stability.

[0138] Example 2

[0139] Implemented with reference to Example 1, the difference is that the system further includes a key parameter control module for controlling the key parameters of the discharging cracking furnace and the feeding cracking furnace; wherein, the key parameters include the single-tube dilution steam flow rate in the furnace chamber, the cracking furnace outlet temperature, and the oxygen content in the furnace chamber.

[0140] Controlling the key parameters of the discharging cracking furnace and the feeding cracking furnace specifically includes:

[0141] When the discharging of the discharging cracking furnace starts, control the single-tube dilution steam flow rate in the furnace chamber of the discharging cracking furnace to increase to the first dilution steam value at the first set rate and keep it constant; when the feeding and discharging process ends, then control the single-tube dilution steam flow rate in the furnace chamber of the discharging cracking furnace to be adjusted from the first dilution steam value to the second dilution steam value at the second set rate and keep it constant.

[0142] When the feeding of the feeding cracking furnace starts, control the single-tube dilution steam flow rate in the furnace chamber of the feeding cracking furnace to decrease to the third dilution steam value at the third set rate and keep it constant; when the feeding and discharging process ends, then adjust the single-tube dilution steam flow rate of the feeding cracking furnace to the single-tube dilution steam flow rate corresponding to the dilution ratio at the fourth set rate.

[0143] Specifically, the first set rate is 20 (kg / h) / min, the second set rate is 100 (kg / h) / min, the first dilution steam value is 4000 kg / h, the second dilution steam value is 4500 kg / h, the third dilution steam value is 3489 kg / h, wherein the dilution ratio is 0.45, the single-tube amount in the furnace chamber is 4, the furnace feeding target value is 31016 kg / h, the third set rate is 92 (kg / h) / t raw material (that is, when 1 t of raw material is fed into the cracking furnace, the single-tube dilution steam amount increases by 92 kg / h), and the initial dilution steam value is 4200 kg / h.

[0144] After detection, by using the counter-cut load adjustment system for the automatic feeding and discharging process of the ethylene cracking furnace described in the present invention, the synchronous progress of the feeding and discharging process is realized. Moreover, during the entire load adjustment process of feeding and discharging, the difference between the discharging amount of the discharging cracking furnace and the feeding amount of the feeding cracking furnace never exceeds 800 kg / h, having the advantages of higher feeding and discharging accuracy, higher switching efficiency of counter-cut load adjustment of the cracking furnace, and higher stability.

[0145] Example 3

[0146] It is implemented by referring to Example 2. The difference is that the key parameters of the discharging cracking furnace and the feeding cracking furnace are controlled, and specifically, it further includes:

[0147] During the discharging and feeding process, control the oxygen content in the furnace chambers of the discharging cracking furnace and the feeding cracking furnace within the first set oxygen content range. When the oxygen content in the furnace chamber of the discharging cracking furnace and / or the feeding cracking furnace is lower than the lower limit value of the first set oxygen content range, open the damper of the corresponding cracking furnace by the first damper amplitude. After a preset time interval, if the oxygen content in the furnace chamber of the corresponding cracking furnace is still lower than the lower limit value of the first set oxygen content range, continue to open the damper of the corresponding cracking furnace by the first damper amplitude until the oxygen content in the furnace chamber of the corresponding cracking furnace is within the first set oxygen content range; when the oxygen content in the furnace chamber of the discharging cracking furnace and / or the feeding cracking furnace is higher than the upper limit value of the first set oxygen content range, close the damper of the corresponding cracking furnace by the second damper amplitude. After a preset time interval, if the oxygen content in the furnace chamber of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, continue to close the damper of the corresponding cracking furnace by the second damper amplitude until the oxygen content in the furnace chamber of the corresponding cracking furnace is within the first set oxygen content range.

[0148] Specifically, the first set oxygen content range is 2 - 3.5%, the upper limit value of the first set oxygen content range is 3.5%, the lower limit value of the oxygen content range is 2%, the first damper amplitude and the second damper amplitude are 2%, and the preset time is 1 min.

[0149] After testing, by using the load adjustment system for the automatic discharging and feeding process of the ethylene cracking furnace of the present invention, the synchronous progress of the discharging and feeding process is realized. And during the entire load adjustment process of discharging and feeding, the difference between the discharging amount of the discharging cracking furnace and the feeding amount of the feeding cracking furnace never exceeds 800 kg / h, having the advantages of high accuracy in discharging and feeding, higher switching efficiency in load adjustment of the cracking furnace for load transfer, and higher stability.

[0150] Example 4

[0151] It is implemented by referring to Example 3. The difference is that the key parameters of the discharging cracking furnace and the feeding cracking furnace are controlled, and specifically, it further includes:

[0152] During the charging and discharging process, control the cracking furnace outlet temperature of the discharging cracking furnace and the charging cracking furnace within the first set temperature range. When the cracking furnace outlet temperature of the discharging cracking furnace and / or the charging cracking furnace is between the first furnace bottom limit value and the second furnace bottom limit value, control the calorific value of the fuel gas to increase by the first amplitude. After a preset time interval, if the cracking furnace outlet temperature of the corresponding cracking furnace is still between the first furnace bottom limit value and the second furnace bottom limit value, control the calorific value of the fuel gas to continue to increase by the first amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range; when the cracking furnace outlet temperature of the discharging cracking furnace and / or the charging cracking furnace is lower than the second furnace bottom limit value, control the calorific value of the fuel gas to increase by the second amplitude. After a preset time interval, if the cracking furnace outlet temperature of the corresponding cracking furnace is still lower than the second furnace bottom limit value, control the calorific value of the fuel gas to continue to increase by the second amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range;

[0153] When the cracking furnace outlet temperature of the discharging cracking furnace and / or the charging cracking furnace is between the first furnace top limit value and the second furnace top limit value, control the calorific value of the fuel gas to decrease by the third amplitude. After a preset time interval, if the cracking furnace outlet temperature of the corresponding cracking furnace is still between the first furnace top limit value and the second furnace top limit value, control the calorific value of the fuel gas to continue to decrease by the third amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range; when the cracking furnace outlet temperature of the discharging cracking furnace and / or the charging cracking furnace is higher than the second furnace top limit value, control the calorific value of the fuel gas to decrease by the fourth amplitude. After a preset time interval, if the cracking furnace outlet temperature of the corresponding cracking furnace is still higher than the second furnace top limit value, control the calorific value of the fuel gas to continue to decrease by the fourth amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range.

[0154] Specifically, the first set temperature range of the discharging cracking furnace is 730 - 740 °C, the first furnace bottom limit value is 730 °C, the second furnace bottom limit value is 725 °C, the first furnace top limit value is 740 °C, and the second furnace top limit value is 745 °C; the first set temperature range of the charging cracking furnace is 745 - 760 °C, the first furnace bottom limit value is 745 °C, the second furnace bottom limit value is 740 °C, the first furnace top limit value is 760 °C, and the second furnace top limit value is 765 °C; the first amplitude and the second amplitude are 0.15 MW, and the third amplitude and the fourth amplitude are 0.3 MW.

[0155] After testing, the load adjustment system for the automatic charging and discharging process of the ethylene cracking furnace described in the present invention realizes the synchronous progress of the charging and discharging process. And during the entire charging and discharging load adjustment process, the difference between the discharging amount of the discharging cracking furnace and the charging amount of the charging cracking furnace never exceeds 650 kg / h, having the advantages of high charging and discharging accuracy, higher switching efficiency of the cracking furnace's load adjustment during the cutover, and higher stability.

[0156] Example 5

[0157] Implemented with reference to Example 4, except that the system further includes an operation navigation function module, which is used to, during the feeding and discharging process, when the damper opening of the discharging cracking furnace and / or the feeding cracking furnace is 0-25%, and the oxygen content in the furnace of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, prompt to check whether the on-site opening is consistent with the central control opening, and check whether all the viewing holes and ignition holes are tightly closed; when the damper opening of the discharging cracking furnace and / or the feeding cracking furnace is 70-100%, and the oxygen content in the furnace of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, stop adjusting the damper opening, prompt to check whether the on-site opening is consistent with the central control opening, and check whether all the viewing holes and ignition holes are tightly closed; when the fuel gas pressure is lower than 0.09 MPa, prompt to close or open the auxiliary burner operation to maintain the fuel gas pressure within 0.2 MPa.

[0158] It has been detected that by using the load adjustment system for the automatic feeding and discharging process of the ethylene cracking furnace according to the present invention, the synchronous progress of the feeding and discharging process is realized, and during the entire load adjustment process of feeding and discharging, the difference between the discharging amount of the discharging cracking furnace and the feeding amount of the feeding cracking furnace never exceeds 650 kg / h, having the advantages of high feeding and discharging accuracy, higher switching efficiency of load adjustment for the cracking furnace, and higher stability.

[0159] Example 6

[0160] Implemented with reference to Example 5, except that the system further includes a key parameter monitoring and alarm module, which is used to monitor the key parameters of feeding and discharging during the feeding and discharging stage, and alarm when the key parameters of feeding and discharging exceed the preset range; the key parameters of feeding and discharging include the cracking furnace outlet temperature, the hydrocarbon flow rate and change rate of a single furnace tube, the total hydrocarbon flow rate and change rate of the main pipe, the single pipe dilution steam flow rate, the fuel gas calorific value, the fuel gas pressure, the furnace O2 content, the CO content in the cracked gas, the pressure after the Venturi tube, the cracking furnace damper opening, the dilution steam ratio, the VHS steam drum liquid level, the VHS temperature, the temperature after the oil cooler, the temperature of the cracking furnace cross section, the hydrocarbon raw material pressure, and the valve position rate of the raw material control valve of a single furnace tube.

[0161] It has been detected that by using the load adjustment system for the automatic feeding and discharging process of the ethylene cracking furnace according to the present invention, the synchronous progress of the feeding and discharging process is realized, and during the entire load adjustment process of feeding and discharging, the difference between the discharging amount of the discharging cracking furnace and the feeding amount of the feeding cracking furnace never exceeds 650 kg / h, having the advantages of high feeding and discharging accuracy, high safety, higher switching efficiency of load adjustment for the cracking furnace, and higher stability.

[0162] Example 7

[0163] Implemented with reference to Embodiment 6, with the difference that the key parameters of material feeding and discharging are monitored, and when the key parameters of material feeding and discharging exceed the preset range, an alarm is given. Specifically, it includes:

[0164] When the key parameters of material feeding and discharging exceed the first preset range, an alarm is given;

[0165] When the key parameters of material feeding and discharging exceed the second preset range, the key parameters of material feeding and discharging that exceed the second preset range are adjusted to within the first preset range at a preset ratio based on their current values, and an alarm is given;

[0166] Wherein, the upper limit value of the second preset range is greater than the upper limit value of the first preset range, the lower limit value of the second preset range is less than the lower limit value of the first preset range, and the preset ratio is ±2%.

[0167] After testing, the system for adjusting the cut load during the automatic material feeding and discharging process of the ethylene cracking furnace according to the present invention realizes the synchronous progress of the material feeding and discharging process, and during the entire process of adjusting the material feeding and discharging load, the difference between the discharging amount of the discharging cracking furnace and the feeding amount of the feeding cracking furnace never exceeds 550 kg / h, having the advantages of high accuracy of material feeding and discharging, high safety, higher switching efficiency of adjusting the cut load of the cracking furnace, and higher stability.

[0168] Embodiment 8

[0169] Implemented with reference to Embodiment 7, with the difference that the system further includes an alarm optimization management module, which is used to automatically shield the instrument alarm of the feeding system when the feeding load of the cracking furnace is less than 70% of the design load, and the indicator light for enabling the material feeding and discharging alarm turns red; when the feeding load is greater than 70% of the design load, the instrument alarm of the feeding system is automatically enabled, and the indicator light for enabling the material feeding and discharging alarm turns green; the types of the instrument alarm of the feeding system include total discharging amount alarm, liquid phase discharging flow alarm of the cracking furnace, gas phase discharging flow alarm of the cracking furnace, discharging interlock pressure alarm, DMDS force alarm, DMDS flow alarm, anti-coking steam pressure difference alarm, cracking furnace outlet temperature alarm, cross-section temperature alarm, quench oil flow alarm, Venturi inlet pressure alarm, cracking gas analysis indication alarm, cross-section flue gas oxygen content alarm, fuel heat load ratio alarm, low liquid raw material flow alarm in the furnace tube, and low gas raw material pressure alarm.

[0170] After testing, the system for adjusting the cut load during the automatic material feeding and discharging process of the ethylene cracking furnace according to the present invention realizes the synchronous progress of the material feeding and discharging process, and during the entire process of adjusting the material feeding and discharging load, the difference between the discharging amount of the discharging cracking furnace and the feeding amount of the feeding cracking furnace never exceeds 550 kg / h, having the advantages of high accuracy of material feeding and discharging, high safety, higher switching efficiency of adjusting the cut load of the cracking furnace, and higher stability.

[0171] Example 9

[0172] Implemented with reference to Example 8, the difference is that the system further includes a deep learning function module, which is used to learn the control advantages and disadvantages of the key parameters of the discharging cracking furnace and the feeding cracking furnace based on empirical values and big data, and derive the optimal control values of the key parameters of the discharging cracking furnace and the feeding cracking furnace.

[0173] After testing, the system for adjusting the cut load during the automatic feeding and discharging process of the ethylene cracking furnace according to the present invention realizes the synchronous progress of the feeding and discharging process, and during the entire load adjustment process of feeding and discharging, the difference between the discharging amount of the discharging cracking furnace and the feeding amount of the feeding cracking furnace never exceeds 500 kg / h, having the advantages of high feeding and discharging accuracy, high safety, higher switching efficiency of the cut load adjustment of the cracking furnace, and higher stability.

[0174] Example 10

[0175] Implemented with reference to Example 9, the difference is that the discharging rate of the main pipe of the furnace chamber of the discharging cracking furnace is 240 kg / h, the discharging rate of a single pipe is 300 kg / h, and the valve position rate of the single-pipe control valve of the furnace chamber of the discharging cracking furnace is 3% / min.

[0176] After testing, the system for adjusting the cut load during the automatic feeding and discharging process of the ethylene cracking furnace according to the present invention realizes the synchronous progress of the feeding and discharging process, and during the entire load adjustment process of feeding and discharging, the difference between the discharging amount of the discharging cracking furnace and the feeding amount of the feeding cracking furnace never exceeds 500 kg / h, having the advantages of high feeding and discharging accuracy, high safety, higher switching efficiency of the cut load adjustment of the cracking furnace, and higher stability.

[0177] The system and method for adjusting the cut load during the automatic feeding and discharging process of the ethylene cracking furnace provided by the present invention can effectively improve the load stability and load switching efficiency of the cracking furnace during the feeding and discharging process by the combined use of the feed load acquisition module and the load adjustment control module for the feeding and discharging process.

[0178] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. To avoid unnecessary repetition, the present invention will not separately describe various possible combinations. But these simple modifications and combinations should also be regarded as the content disclosed by the present invention and all fall within the protection scope of the present invention.

Claims

1. An opposite cutting load adjustment system for the automatic feeding and discharging process of an ethylene cracking furnace, characterized in that, The system includes: A feed load acquisition module, which is used to acquire the feed load of each cracking furnace in real time, obtain the remaining feeding load of each cracking furnace according to the feed load of each cracking furnace, and select two cracking furnaces that meet the switching conditions as the feeding cracking furnace and the discharging cracking furnace respectively according to the feed load and the remaining feeding load of each cracking furnace; A feeding and discharging process load adjustment control module, which is used to control the discharging cracking furnace to discharge materials according to the feed load of the discharging cracking furnace, and simultaneously control the feeding cracking furnace to feed materials during the process of controlling the discharging cracking furnace to discharge materials; A feeding and discharging execution module, which is used to perform feeding and discharging according to the control instructions of the feeding and discharging process load adjustment control module.

2. The system according to claim 1, characterized in that, The controlling the discharging cracking furnace to discharge materials according to the feed load of the discharging cracking furnace specifically includes: In the first discharging stage, discharging materials through the furnace main pipe of the discharging cracking furnace at a first discharging rate to a first discharging value, and stabilizing for a set time; In the second discharging stage, discharging materials through the single furnace tubes of the discharging cracking furnace at a second discharging rate to a second discharging value, and stabilizing for a set time; In the third discharging stage, discharging all the remaining materials to be discharged through the control valve of the single furnace tube of the discharging cracking furnace at a valve position rate.

3. The system according to claim 2, characterized in that, The simultaneously controlling the feeding cracking furnace to feed materials during the process of controlling the discharging cracking furnace to discharge materials specifically includes: When in the first discharging stage, feeding materials through the control valve of the single furnace tube of the feeding cracking furnace at a valve position rate corresponding to the first discharging rate, and stabilizing for a set time after the feeding ends; When in the second discharging stage, feeding materials through the single furnace tubes of the feeding cracking furnace at a feeding rate corresponding to the second discharging rate, and stabilizing for a set time after the feeding ends; When in the third feeding stage, feeding materials through the furnace main pipe of the feeding cracking furnace at a feeding rate corresponding to the valve position rate of the control valve of the single furnace tube of the discharging cracking furnace.

4. The system according to claim 3, wherein The first discharging value is 60-80% of the feed load of the discharging cracking furnace, the second discharging value is 20-45% of the feed load of the discharging cracking furnace, and the set time is 0-20 min; the first discharging rate is 50-500 (kg / h) / min, the second discharging rate is 100-800 (kg / h) / min, and the valve position rate is 0.5-10% / min.

5. The system according to any one of claims 1-4, characterized in that, The system further includes a feeding and discharging pre-state confirmation module, which is used to confirm the initial states of the discharging cracking furnace and the feeding cracking furnace before feeding and discharging; The confirming the initial state of the discharging cracking furnace before feeding and discharging specifically includes: Confirming the initial discharging parameters of the discharging cracking furnace, and when the initial discharging parameters are within the initial range, indicating that discharging can be performed, and when the initial discharging parameters are not within the initial range, alarming one or more of the initial discharging parameters that are not within the initial range; Confirming the initial feeding parameters of the feeding cracking furnace, and when the initial feeding parameters are within the initial range, indicating that feeding can be performed, and when the initial feeding parameters are not within the initial range, alarming one or more of the initial feeding parameters that are not within the initial range.

6. The system according to claim 5, characterized in that, The initial discharging parameters include sulfur injection amount, cracking furnace outlet temperature, and ultra-high pressure steam temperature; the initial feeding parameters include quench oil temperature, pressure after the Venturi tube, single-tube dilution steam flow rate in the furnace, cracking furnace outlet temperature, and ultra-high pressure steam temperature.

7. The system according to claim 6, wherein The initial range of the sulfur injection amount of the discharging cracking furnace is 2 - 5 kg / h, the initial range of the cracking furnace outlet temperature is 730 - 750 °C, and the initial range of the ultra-high pressure steam temperature is 505 - 520 °C; the initial range of the quench oil temperature of the feeding cracking furnace is 190 - 210 °C, the initial range of the pressure after the Venturi tube is 0.04 - 0.1 MPa, the initial range of the single-tube dilution steam flow rate in the furnace is 3800 - 4500 kg / h, the initial range of the ultra-high pressure steam temperature is 480 - 500 °C, and the initial range of the cracking furnace outlet temperature is 720 - 740 °C.

8. The system according to claim 1, characterized in that, The system further includes a key parameter control module for controlling the key parameters of the discharging cracking furnace and the feeding cracking furnace; wherein, the key parameters include single-tube dilution steam flow rate in the furnace, cracking furnace outlet temperature, and furnace oxygen content.

9. The system according to claim 8, wherein The control of the key parameters of the discharging cracking furnace and the feeding cracking furnace specifically includes: When the discharging of the discharging cracking furnace starts, control the single-tube dilution steam flow rate in the furnace of the discharging cracking furnace to increase to a first dilution steam value at a first set rate and keep it constant; when the discharging and feeding process ends, then control the single-tube dilution steam flow rate in the furnace of the discharging cracking furnace to adjust from the first dilution steam value to a second dilution steam value at a second set rate and keep it constant; When the feeding of the feeding cracking furnace starts, control the single-tube dilution steam flow rate in the furnace of the feeding cracking furnace to decrease to a third dilution steam value at a third set rate and keep it constant; when the discharging and feeding process ends, then adjust the single-tube dilution steam flow rate in the furnace of the feeding cracking furnace to the single-tube dilution steam flow rate corresponding to the dilution ratio at a fourth set rate.

10. The system according to claim 9, characterized in that, The control of the key parameters of the discharging cracking furnace and the feeding cracking furnace specifically further includes: During the discharging and feeding process, control the furnace oxygen content of the discharging cracking furnace and the feeding cracking furnace within a first set oxygen content range, and when the furnace oxygen content of the discharging cracking furnace and / or the feeding cracking furnace is lower than the lower limit value of the first set oxygen content range, open the damper of the corresponding cracking furnace by a first damper amplitude. After a preset time interval, if the furnace oxygen content of the corresponding cracking furnace is still lower than the lower limit value of the first set oxygen content range, continue to open the damper of the corresponding cracking furnace by the first damper amplitude until the furnace oxygen content of the corresponding cracking furnace is within the first set oxygen content range; when the furnace oxygen content of the discharging cracking furnace and / or the feeding cracking furnace is higher than the upper limit value of the first set oxygen content range, close the damper of the corresponding cracking furnace by a second damper amplitude. After a preset time interval, if the furnace oxygen content of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, continue to close the damper of the corresponding cracking furnace by the second damper amplitude until the furnace oxygen content of the corresponding cracking furnace is within the first set oxygen content range.

11. The system according to claim 10, wherein The control of the key parameters of the discharging cracking furnace and the feeding cracking furnace specifically further includes: During the process of discharging and feeding materials, control the cracking furnace outlet temperature of the discharging cracking furnace and the feeding cracking furnace within the first set temperature range. When the cracking furnace outlet temperature of the discharging cracking furnace and / or the feeding cracking furnace is between the first furnace bottom limit value and the second furnace bottom limit value, control the calorific value of the fuel gas to increase by the first amplitude. After an interval of a preset time, if the cracking furnace outlet temperature of the corresponding cracking furnace is still between the first furnace bottom limit value and the second furnace bottom limit value, control the calorific value of the fuel gas to continue to increase by the first amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range; when the cracking furnace outlet temperature of the discharging cracking furnace and / or the feeding cracking furnace is lower than the second furnace bottom limit value, control the calorific value of the fuel gas to increase by the second amplitude. After an interval of a preset time, if the cracking furnace outlet temperature of the corresponding cracking furnace is still lower than the second furnace bottom limit value, control the calorific value of the fuel gas to continue to increase by the second amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range; When the cracking furnace outlet temperature of the discharging cracking furnace and / or the feeding cracking furnace is between the first furnace top limit value and the second furnace top limit value, control the calorific value of the fuel gas to decrease by the third amplitude. After an interval of a preset time, if the cracking furnace outlet temperature of the corresponding cracking furnace is still between the first furnace top limit value and the second furnace top limit value, control the calorific value of the fuel gas to continue to decrease by the third amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range; when the cracking furnace outlet temperature of the discharging cracking furnace and / or the feeding cracking furnace is higher than the second furnace top limit value, control the calorific value of the fuel gas to decrease by the fourth amplitude. After an interval of a preset time, if the cracking furnace outlet temperature of the corresponding cracking furnace is still higher than the second furnace top limit value, control the calorific value of the fuel gas to continue to decrease by the fourth amplitude until the cracking furnace outlet temperature of the corresponding cracking furnace is within the first set temperature range.

12. The system according to claim 11, wherein The first set rate is 10 - 150 (kg / h) / min, the second set rate is 50 - 500 (kg / h) / min, the first dilution steam value is 3500 - 4500 kg / h, the second dilution steam value is 3800 - 5500 kg / h, the third dilution steam value is the furnace feeding target value * dilution ratio / single furnace tube quantity of the furnace, and the dilution ratio is 0.3 - 0.55; the third set rate is (initial dilution steam value - third dilution steam value) * 1000 / (furnace feeding target value / single furnace tube quantity of the furnace), the fourth set rate is 50 - 500 (kg / h) / min, the first set oxygen content range is 1 - 10%, the first damper amplitude and the second damper amplitude are 0.5 - 5%, the first set temperature range is 710 - 780 °C, the first furnace lower limit value is the lower limit value of the first set temperature range, the second furnace lower limit value is less than the first furnace lower limit value and the difference between the two is 2 - 10 °C, the first furnace upper limit value is the upper limit value of the first set temperature range, the second furnace upper limit value is greater than the first furnace upper limit value and the difference between the two is 2 - 10 °C, the first amplitude and the second amplitude are 0 - 0.4 MW, and the third amplitude and the fourth amplitude are 0.1 - 0.6 MW.

13. The system according to any one of claims 10 - 12, characterized in that, The system further includes an operation navigation function module, which is used to, during the feeding and discharging process, when the damper opening of the discharging cracking furnace and / or the feeding cracking furnace is 0 - 25%, and the furnace oxygen content of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, prompt to check whether the on-site opening is consistent with the central control opening, and check whether all the viewing holes and ignition holes are tightly closed; when the damper opening of the discharging cracking furnace and / or the feeding cracking furnace is 70 - 100%, and the furnace oxygen content of the corresponding cracking furnace is still higher than the upper limit value of the first set oxygen content range, then stop adjusting the damper opening, prompt to check whether the on-site opening is consistent with the central control opening, and check whether all the viewing holes and ignition holes are tightly closed; when the fuel gas pressure is lower than 0.05 - 0.1 MPa, prompt to close or open the auxiliary burner operation to maintain the fuel gas pressure within 0.1 - 0.3 MPa.

14. The system according to claim 1, wherein The system further includes a key parameter monitoring and alarm module, which is used to monitor the key parameters of feeding and discharging during the feeding and discharging stage, and alarm when the key parameters of feeding and discharging exceed the preset range.

15. The system according to claim 14, wherein The key parameters of feeding and discharging include the cracking furnace outlet temperature, the single furnace tube carbon hydrocarbon flow rate and its change rate, the total carbon hydrocarbon flow rate of the main pipe and its change rate, the single tube dilution steam flow rate, the fuel gas calorific value, the fuel gas pressure, the furnace O2 content, the CO content in the cracked gas, the pressure after the Venturi tube, the cracking furnace damper opening, the dilution steam ratio, the VHS steam drum liquid level, the VHS temperature, the temperature after the oil cooler, the cracking furnace cross-section temperature, the carbon hydrocarbon raw material pressure, and the valve position rate of the single furnace tube raw material control valve.

16. The system according to claim 14 or 15, characterized in that Monitoring the key parameters of feeding and discharging and alarming when the key parameters of feeding and discharging exceed the preset range specifically includes: Alarm when the key parameters of feeding and discharging exceed the first preset range; When the key feed / discharge parameters exceed the second preset range, adjust the key feed / discharge parameters that exceed the second preset range to within the first preset range based on their current values at a preset ratio, and give an alarm. Among them, the upper limit value of the second preset range is greater than the upper limit value of the first preset range, the lower limit value of the second preset range is less than the lower limit value of the first preset range, and the preset ratio is ±0.1% - 10%.

17. The system according to claim 1, characterized in that, The system further includes an alarm optimization management module, which is used to automatically shield the instrument alarms of the feed system and turn on the prompt light of the feed / discharge alarm to red when the feed load of the cracking furnace is less than 65 - 75% of the design load. When the feed load is greater than 65 - 75% of the design load, automatically enable the instrument alarms of the feed system and turn on the prompt light of the feed / discharge alarm to green.

18. The system according to claim 17, wherein The types of the instrument alarms of the feed system include total discharge alarm, liquid phase discharge flow alarm of the cracking furnace, gas phase discharge flow alarm of the cracking furnace, discharge interlock pressure alarm, DMDS force alarm, DMDS flow alarm, anti-coking steam pressure difference alarm, cracking furnace outlet temperature alarm, cross-section temperature alarm, quench oil flow alarm, Venturi inlet pressure alarm, cracking gas analysis indication alarm, cross-section flue gas oxygen content alarm, fuel heat load ratio alarm, low flow alarm of the liquid raw material in the furnace tube, and low pressure alarm of the gas raw material.

19. The system according to claim 8, wherein The system further includes a deep learning function module, which is used to learn the control advantages and disadvantages of the key parameters of the discharge cracking furnace and the feed cracking furnace based on empirical values and big data, and derive the optimal control values of the key parameters of the discharge cracking furnace and the feed cracking furnace.

20. The system according to claim 1, wherein The system further includes a control performance evaluation module, which is used to collect the loop information of the cracking furnace in real time, evaluate the control loop performance of the cracking furnace according to the loop information, and give an alarm when the control loop performance of the cracking furnace is abnormal.

21. A method for adjusting the cut load during the automatic feeding and discharging process of an ethylene cracking furnace, characterized in that, Applied to the system described in any one of the above claims 1 - 20, the method includes: Using a feed load acquisition module to obtain the feed load of each cracking furnace in real time, obtaining the remaining feed load of each cracking furnace according to the feed load of each cracking furnace, and selecting two cracking furnaces that meet the switching conditions as the feed cracking furnace and the discharge cracking furnace respectively according to the feed load and the remaining feed load of each cracking furnace. Using a feed / discharge process load adjustment control module to control the discharge cracking furnace to discharge according to the feed load of the discharge cracking furnace, and simultaneously control the feed cracking furnace to feed during the process of controlling the discharge cracking furnace to discharge. Using a feed / discharge execution module to perform feed / discharge according to the control instructions of the feed / discharge process load adjustment control module.

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