A chemical plant VOC waste gas co-boiler blending combustion treatment method and system

Abstract

This invention discloses a method and system for co-firing VOC waste gas in chemical plants using boilers, belonging to the field of data monitoring technology. The system includes: a data acquisition module, a real-time judgment module, a ratio analysis module, a waste gas treatment module, a leakage monitoring module, a control and processing module, and an associated storage module. This invention dynamically generates and executes co-firing ratio adjustment commands based on the removal rate obtained from real-time comparison of initial and emission concentrations to optimize furnace operating conditions. It also quantitatively calculates the sealing leakage rate of the emergency vent valve in real time to control the safety status, achieving stable compliance with waste gas treatment efficiency and improving boiler operation safety. This solves the problems in existing technologies where the co-firing process is crude, leading to fluctuations in removal rates and a high risk of exceeding emission standards, and the status of emergency safety devices is unknown.

Description

Technical Field

[0001] This invention relates to the field of data monitoring technology, and in particular to a method and system for treating VOC waste gas in chemical plants by co-firing with boilers. Background Technology

[0002] With increasingly stringent environmental regulations, extremely high requirements have been placed on the removal efficiency and emission concentration of volatile organic compounds (VOCs) generated during chemical production processes, especially those from coal grinding processes. Against this backdrop, achieving ultra-low emissions of waste gases economically, efficiently, and safely has become a key focus of the industry.

[0003] In related technologies, the treatment of such waste gases mainly employs independent incineration or adsorption devices, which suffers from high investment and operating costs; alternatively, a simple boiler co-firing method is used, but this lacks precise control and safety monitoring of the co-firing process, posing risks of unstable treatment efficiency and emissions exceeding standards due to fluctuations in waste gas concentration or boiler operating conditions. Furthermore, the safety status of emergency discharge pipelines cannot be effectively guaranteed. In summary, existing technologies suffer from problems such as a crude waste gas co-firing process leading to fluctuating removal rates and a high risk of emissions exceeding standards, and the unpredictable status of emergency safety devices. Summary of the Invention

[0004] This application provides a method and system for treating VOC waste gas in chemical plants by co-firing it into a boiler. This solves the problems in the prior art where the co-firing process is crude, leading to fluctuations in removal rate and a high risk of exceeding emission standards, and the status of emergency safety devices is unknown. This achieves stable compliance of waste gas treatment efficiency and improves boiler operation safety.

[0005] This application provides a method for treating VOC waste gas in a chemical plant by co-firing it in a boiler. The method is applied to a VOC waste gas treatment system in a chemical plant by co-firing it in a boiler, and includes: Acquire the initial exhaust gas concentration data collected from the exhaust gas sampling point, and acquire the emission flue gas concentration data collected from the boiler tail flue monitoring point; Based on the initial exhaust gas concentration data and the emission flue gas concentration data, the real-time removal rate data is calculated, and it is determined whether the real-time removal rate data meets the preset removal rate threshold. When the real-time removal rate data meets the preset removal rate threshold, the real-time operating condition data of the boiler furnace is obtained, and the real-time operating condition data is matched with the emission flue gas concentration data to calculate the waste gas co-firing ratio adjustment command. According to the waste gas co-firing ratio adjustment instruction, the inlet flow rate of the waste gas access pipeline is adjusted to obtain the adjusted waste gas flow rate and introduce it into the boiler furnace for co-firing treatment. Real-time acquisition of the opening status and opening degree data of the induction shut-off valve on the emergency vent pipe, and calculation of the sealing leakage rate data; When the sealing leakage rate exceeds the preset leakage threshold, or when a boiler shutdown signal is received, the control sensor shut-off valve is switched to the fully open state to guide the exhaust gas flow into the emergency vent pipe for emergency discharge treatment. The initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and seal leakage rate data are stored together.

[0006] Furthermore, the acquisition of initial exhaust gas concentration data collected from exhaust gas sampling points and exhaust gas concentration data collected from boiler tail flue monitoring points includes: The mass concentration of volatile organic compounds in the waste gas to be treated was obtained by setting sampling points on the waste gas collection pipeline of the coal mill, which served as the initial waste gas concentration data. Data on the concentration of non-methane total hydrocarbons and methanol in the flue gas after combustion are obtained through online monitoring instruments and used as emission flue gas concentration data.

[0007] Furthermore, the calculation of real-time removal rate data based on initial exhaust gas concentration data and emission flue gas concentration data includes: The initial exhaust gas concentration data is used as the denominator, and the difference between the initial exhaust gas concentration data and the emission flue gas concentration data is used as the numerator to calculate the percentage value. This percentage value is defined as the real-time removal rate data.

[0008] Furthermore, the step of matching real-time operating condition data with emission flue gas concentration data to calculate the waste gas co-firing ratio adjustment instruction includes: Based on the real-time values ​​of non-methane total hydrocarbons and methanol in the flue gas concentration data, a preset operating condition comparison table is retrieved to determine the corresponding target combustion air ratio. The target combustion air ratio is compared with the current air volume in the real-time operating data to generate an electrical signal for driving the damper actuator to move. The electrical signal is the exhaust gas co-combustion ratio adjustment command.

[0009] Furthermore, the real-time acquisition of the opening status data and opening degree data of the inductive shut-off valve on the emergency vent pipe, and the calculation of the sealing leakage rate data, includes: The valve stem displacement sensor value of the inductive shut-off valve in the closed command state is collected as the opening data; The preset mapping curve between valve opening and fluid flow rate is retrieved, and the real-time overflow flow rate is calculated by combining the opening data. The real-time overflow flow rate is compared with the total exhaust gas flow rate to obtain the seal leakage rate data.

[0010] Furthermore, the sealing leakage rate data is used for interlocking control of the induction shut-off valve, including: When the seal leakage rate data is within the preset range, maintain the current state of the inductive shut-off valve; When the seal leakage rate exceeds the preset leakage threshold, the system triggers an alarm signal and blocks the exhaust gas co-firing ratio adjustment command.

[0011] Furthermore, the step of directing the exhaust gas flow into the emergency vent pipe for emergency discharge treatment includes: Receive the cut-off signal from the boiler's main fuel supply system as the boiler shutdown status signal; Based on the boiler shutdown status signal, the actuator drives the inlet valve of the exhaust gas inlet pipe to close and drives the induction shut-off valve to open to the maximum stroke position.

[0012] Furthermore, the step of associating and storing the initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and seal leakage rate data includes: The initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and sealing leakage rate data are packaged into data packets according to timestamp information and stored in the historical database. Set the automatic cleanup cycle for the historical database to ensure that the data packets are retained for the maximum preset time period.

[0013] Furthermore, after the real-time removal rate data and the sealing leakage rate data are correlated and stored, the process further includes: introducing the adjusted exhaust gas flow into the boiler furnace for co-firing treatment, including: The exhaust gas flow is transported through pipelines to the secondary air nozzle of the boiler; Alternatively, the exhaust gas stream can be mixed with the main combustion air and then introduced into the furnace through the combustion air duct.

[0014] This application provides a VOC waste gas co-firing treatment system for chemical plants, which is used to implement a method for VOC waste gas co-firing treatment in chemical plants. The system includes: a data acquisition module, a real-time judgment module, a ratio analysis module, a waste gas treatment module, a leakage monitoring module, a control processing module, and an associated storage module. The data acquisition module is used to acquire the initial exhaust gas concentration data collected from the exhaust gas sampling point and the emission flue gas concentration data collected from the boiler tail flue monitoring point. The real-time judgment module is used to calculate the real-time removal rate data based on the initial exhaust gas concentration data and the emission flue gas concentration data, and to determine whether the real-time removal rate data meets the preset removal rate threshold. The ratio analysis module is used to obtain the real-time operating condition data of the boiler furnace when the real-time removal rate data meets the preset removal rate threshold, and to match the real-time operating condition data with the emission flue gas concentration data to calculate the waste gas co-firing ratio adjustment command. The waste gas treatment module is used to adjust the inlet flow rate of the waste gas inlet pipe according to the waste gas co-firing ratio adjustment command, obtain the adjusted waste gas flow rate and introduce it into the boiler furnace for co-firing treatment. The leakage monitoring module is used to acquire the opening status data and opening degree data of the induction shut-off valve on the emergency venting pipe in real time, and calculate the sealing leakage rate data. The control and processing module is used to control the inductive shut-off valve to switch to the fully open state when the sealing leakage rate data exceeds the preset leakage threshold or when a boiler shutdown status signal is received, so as to guide the exhaust gas flow into the emergency vent pipe for emergency discharge treatment. The associated storage module is used to associate and store initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and seal leakage rate data.

[0015] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: This application provides a method and system for co-firing VOC waste gas in chemical plants using boilers. The system acquires real-time concentration data of the waste gas before and after treatment and calculates the removal rate. Based on this removal rate, and combined with the boiler's real-time operating conditions, it dynamically generates co-firing ratio adjustment commands to precisely control the waste gas inlet flow. Simultaneously, it monitors and quantifies the sealing leakage rate of the shut-off valve on the emergency venting pipeline. Based on this leakage rate data and the boiler's operating status, it performs intelligent safety interlock control of the co-firing process and emergency emission path. Finally, it stores the entire process data in association.

[0016] In this process, the end-of-pipe emission compliance requirements (such as non-methane total hydrocarbon concentration) and the front-end treatment process (co-firing ratio) are calculated in real time to solve the problem of unstable treatment efficiency caused by fluctuations in waste gas composition and load in traditional co-firing processes, thus ensuring continuous compliance of emission concentration.

[0017] Furthermore, by upgrading the shut-off valve on the emergency venting pipeline from a simple mechanical component to an intelligent monitoring unit with status perception and leakage quantification, and using its sealing integrity data as a prerequisite for judging whether the entire co-firing process can operate safely, an active and quantifiable safety redundancy system was constructed, which improved the safety level of the process and solved the problem of difficult precise control of safety risks in integrated governance solutions for small and medium-sized chemical plants. Attached Figure Description

[0018] Figure 1 A flowchart illustrating a method for treating VOC emissions from a chemical plant by co-firing in a boiler, as provided in this application embodiment; Figure 2 This is a schematic diagram of a chemical plant VOC waste gas co-firing and treatment system provided in an embodiment of this application. Detailed Implementation

[0019] This application provides a method and system for treating VOC waste gas in chemical plants by co-firing it in a boiler. It solves the problems in the prior art where the co-firing process is crude, leading to fluctuations in removal rate and a high risk of exceeding emission standards, and the status of emergency safety devices is unknown. By establishing a removal rate evaluation mechanism based on real-time comparison of initial and emission concentrations, it dynamically generates and executes co-firing ratio adjustment commands to optimize furnace conditions, and quantitatively calculates the sealing leakage rate of the emergency vent valve in real time to control the safety status in a coordinated manner. This achieves stable compliance of waste gas treatment efficiency and improves boiler operation safety.

[0020] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0021] like Figure 1 As shown, this application provides a method for treating VOC waste gas in a chemical plant by co-firing it in a boiler. This method is applied to a VOC waste gas treatment system in a chemical plant by co-firing it in a boiler, and includes: Acquire the initial exhaust gas concentration data collected from the exhaust gas sampling point, and acquire the emission flue gas concentration data collected from the boiler tail flue monitoring point.

[0022] Based on the initial exhaust gas concentration data and the emission flue gas concentration data, the real-time removal rate data is calculated, and it is determined whether the real-time removal rate data meets the preset removal rate threshold.

[0023] The preset removal rate threshold is set to 99%. The judgment logic is: if the real-time removal rate data... If the condition is met, then the condition is satisfied; otherwise, it is not satisfied.

[0024] When the real-time removal rate data meets the preset removal rate threshold, the real-time operating condition data of the boiler furnace is obtained. The real-time operating condition data is matched with the emission flue gas concentration data to calculate the waste gas co-firing ratio adjustment command.

[0025] Real-time operating data includes at least the following key operating parameters: main fuel injection rate, total combustion air volume, furnace temperature and pressure, etc. The system can read this data in real time from the boiler distributed control system (DCS) or programmable logic controller (PLC).

[0026] The exhaust gas co-firing ratio adjustment command is an output signal used to control the opening of the regulating valve (such as an electric regulating valve or a pneumatic regulating valve) on the exhaust gas inlet pipe, thereby changing the exhaust gas flow rate and realizing the adjustment of the ratio of exhaust gas to main combustion air.

[0027] According to the instruction to adjust the waste gas co-firing ratio, the inlet flow rate of the waste gas access pipeline is adjusted to obtain the adjusted waste gas flow rate and introduce it into the boiler furnace for co-firing treatment.

[0028] Real-time acquisition of the opening status and degree data of the induction shut-off valve on the emergency venting pipe, and calculation of the sealing leakage rate data.

[0029] When the sealing leakage rate exceeds the preset leakage threshold, or when a boiler shutdown signal is received, the control sensor shut-off valve switches to the fully open state, directing the exhaust gas flow into the emergency vent pipe for emergency discharge treatment.

[0030] The default leakage threshold is set to 0.5%.

[0031] The boiler shutdown status signal is a digital (switching) signal issued by the boiler control system when the main fuel supply to the boiler is cut off, the blower stops, or a shutdown command is issued.

[0032] The initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and seal leakage rate data are stored together.

[0033] Related storage refers to storing all data (including timestamps) in the same database or data file so that related queries and analyses can be performed using timestamps or transaction IDs.

[0034] Furthermore, initial exhaust gas concentration data collected from exhaust gas sampling points and emission flue gas concentration data collected from boiler tail flue monitoring points are obtained, including: By setting sampling points on the exhaust gas collection pipeline of the coal mill, the mass concentration of volatile organic compounds in the exhaust gas to be treated is obtained as the initial exhaust gas concentration data.

[0035] Data on the concentration of non-methane total hydrocarbons and methanol in the flue gas after combustion are obtained through online monitoring instruments and used as emission flue gas concentration data.

[0036] The specific method for obtaining concentration at sampling points involves controlling a sampling pump to draw sample gas from the sampling port on the exhaust gas collection pipeline. After pretreatment (such as filtration, dehumidification, and cooling), the sample gas is sent to an online gas chromatograph (GC) or flame ionization detector (FID) for analysis to obtain the total volatile organic compound (TVOC) mass concentration in mg / m³. This value is used as the initial exhaust gas concentration data. .

[0037] Online monitoring instruments refer to the component monitors in a continuous emission monitoring system (CEMS) specifically designed to measure the composition of gaseous pollutants. The system reads the non-methane total hydrocarbon concentration in mg / m³ in real time from the data output interface of these monitors. and methanol concentration The emission concentration data consists of these two specific concentration values.

[0038] Furthermore, based on the initial exhaust gas concentration data and the emission flue gas concentration data, the real-time removal rate data is calculated, including: The initial exhaust gas concentration data is used as the denominator, and the difference between the initial exhaust gas concentration data and the emission flue gas concentration data is used as the numerator to calculate the percentage value. This percentage value is defined as the real-time removal rate data.

[0039] Specific real-time removal rate data The calculation formula is: .

[0040] in, This provides real-time removal rate data. This is the initial exhaust gas concentration data, i.e., TVOC concentration; For emission flue gas concentration data, this is used in conjunction with... The corresponding total VOCs equivalent concentration.

[0041] Because what is obtained from monitoring is and The two are usually added together as Approximate value, When calculating, it is necessary to ensure that... and The categories of pollutants characterized are consistent.

[0042] The system calculates Then, it was compared with 99%.

[0043] Furthermore, by matching the emission flue gas concentration data with the real-time operating condition data, the waste gas co-firing ratio adjustment command is calculated, including: Based on the real-time values ​​of non-methane total hydrocarbons and methanol in the flue gas concentration data, a preset operating condition comparison table is retrieved to determine the corresponding target combustion air ratio.

[0044] The target combustion air ratio is compared with the current air volume in the real-time operating data to generate an electrical signal for driving the damper actuator to move. The electrical signal is the exhaust gas co-combustion ratio adjustment command.

[0045] The operating condition comparison table is a data table pre-established through boiler combustion commissioning. Its input is the emission flue gas concentration data (…). and The combination or maximum value of the target combustion air ratio is the output. This refers to the percentage of exhaust gas flow rate to the total combustion air flow rate. For example, when... At that time, the corresponding table It may be reduced by 2%.

[0046] The instructions include: Step 1: Find the target combustion air ratio from the operating condition comparison table. .

[0047] Step 2: Obtain the current total combustion air volume from real-time operating data. .

[0048] Step 3, calculate the target exhaust gas flow rate : .

[0049] Step 4: Obtain the current exhaust gas flow rate through the flow meter on the exhaust gas pipeline. .

[0050] Step 5: Calculate the flow deviation and generate a 4-20mA or 0-10V analog electrical signal using a proportional-integral-derivative (PID) controller algorithm. This signal is the exhaust gas co-firing ratio adjustment command and is sent to the exhaust gas intake regulating valve.

[0051] Furthermore, the opening status and degree data of the inductive shut-off valve on the emergency vent pipe are acquired in real time, and the sealing leakage rate data is calculated, including: The valve stem displacement sensor value of the inductive shut-off valve in the closed command state is collected as the opening data.

[0052] The preset mapping curve between valve opening and fluid flow rate is retrieved, and the real-time overflow flow rate is calculated by combining the opening data.

[0053] The real-time overflow flow rate is compared with the total exhaust gas flow rate to obtain the seal leakage rate data.

[0054] The opening data is obtained by the system reading the valve position transmitter signal of the shut-off valve to obtain the actual valve plate position when the valve is closed. (Usually expressed as 0-100%, with 0% representing all off).

[0055] Valve leakage mapping curves provided by valve manufacturers are used to describe the leakage at different valve positions under a specific pressure differential. (When not fully shut down) Corresponding real-time overflow flow Based on the current measurements And pipeline pressure data, obtained by looking up curves or interpolation calculations. .

[0056] Calculate the seal leakage rate using the following formula: .

[0057] in, For seal leakage rate data, This refers to the real-time overflow flow rate, i.e., the leakage rate. This refers to the total exhaust gas flow rate, which is the flow rate during normal operation.

[0058] Furthermore, the seal leakage rate data is used for interlocking control of the induction shut-off valve, including: When the seal leakage rate data is within the preset range, maintain the current state of the induction shut-off valve.

[0059] When the seal leakage rate exceeds the preset leakage threshold, the system triggers an alarm signal and blocks the exhaust gas co-firing ratio adjustment command.

[0060] Preset range refers to leakage rate Within acceptable limits, for example .

[0061] The interlocking control logic includes: like The system does not perform any control actions, and the shut-off valve remains closed.

[0062] like The system immediately triggers an audible and visual alarm signal on the human-machine interface of the central control system (CMS). At the same time, it blocks the exhaust gas blending ratio adjustment command sent to the exhaust gas intake regulating valve, forcibly locking the regulating valve at the current opening or a safe opening to prevent more exhaust gas from entering the unsafe pipeline due to valve failure.

[0063] Furthermore, the exhaust gas flow is directed into the emergency vent pipe for emergency discharge treatment, including: The system receives a cut-off signal from the main fuel supply system of the boiler as a boiler shutdown status signal.

[0064] Based on the boiler shutdown status signal, the actuator drives the inlet valve of the exhaust gas inlet pipe to close and drives the induction shut-off valve to open to the maximum stroke position.

[0065] Specific switching steps: Receive a boiler shutdown status signal, such as "main fuel valve closed" signal.

[0066] Immediately issue a full-close command to the intake regulating valve on the exhaust gas inlet pipe.

[0067] At the same time, a full-open command is issued to the inductive shut-off valve on the emergency vent pipe.

[0068] Continuously monitor the valve position feedback signals of these two valves to ensure that the intake regulating valve is fully closed (feedback close to 0%) and the induction shut-off valve is fully open (feedback 100%). At this time, the exhaust gas generated in the coal mill will be discharged at high altitude through the fully open emergency vent pipe via the original path.

[0069] Furthermore, the initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and seal leakage rate data are linked and stored, including: The initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and seal leakage rate data are packaged into data packets according to timestamp information and stored in the historical database.

[0070] Set the automatic cleanup cycle for the historical database to ensure that the data packets are retained for the maximum preset time period.

[0071] Data packet encapsulation refers to the process of encapsulating data for each group of synchronously acquired or processed data. , , , , The data, along with related flow rates, valve positions, etc., are stamped with the same timestamp (accurate to the second) and encapsulated into a single data record.

[0072] Historical databases are either real-time databases (such as PI, iHistorian) or relational databases (such as SQL Server, Oracle). Data records are stored in them.

[0073] Automatic cleanup and periodicity: System administrators configure data retention policies in the database. All historical data is retained for at least 5 years. The automatic cleanup cycle for all historical data or the upper limit of the data retention period can be set to 5 years. Automatic database tasks will periodically delete data older than 5 years.

[0074] Furthermore, after the real-time removal rate data and the sealing leakage rate data are correlated and stored, the process also includes: introducing the adjusted exhaust gas flow into the boiler furnace for co-firing treatment, including: The exhaust gas flow is transported through pipelines to the secondary air nozzle of the boiler.

[0075] Alternatively, the exhaust gas stream can be mixed with the main combustion air and then introduced into the furnace through the combustion air duct.

[0076] The secondary air nozzle specifically refers to the regulated exhaust gas flow that is directly connected to the original secondary air box or second-layer air nozzle of the boiler body through an independent pipe, and is injected into the furnace together with the secondary air from staged combustion.

[0077] The mixing of main and auxiliary combustion air specifically refers to the following: the regulated exhaust gas flow is injected into the main and auxiliary combustion air duct or the outlet duct of the primary air fan, and is fully mixed with the main and auxiliary combustion air from the air preheater. After forming mixed air, it is sent into the furnace through the burner combustion air duct.

[0078] The common goal of both methods is to ensure that the exhaust gas is fully mixed with the main fuel (pulverized coal, natural gas) in the high-temperature zone of the boiler furnace (usually >850°C) and remains for a sufficient time (usually >2 seconds) to ensure that VOCs are completely oxidized and decomposed into carbon dioxide and water.

[0079] like Figure 2 As shown in the figure, this application provides a chemical plant VOC waste gas co-firing boiler treatment system for implementing the chemical plant VOC waste gas co-firing boiler treatment method, including: a data acquisition module, a real-time judgment module, a ratio analysis module, a waste gas treatment module, a leakage monitoring module, a control processing module, and an associated storage module.

[0080] The data acquisition module is used to acquire the initial exhaust gas concentration data collected from the exhaust gas sampling point and the emission flue gas concentration data collected from the boiler tail flue monitoring point.

[0081] The real-time judgment module is used to calculate the real-time removal rate data based on the initial exhaust gas concentration data and the emission flue gas concentration data, and to determine whether the real-time removal rate data meets the preset removal rate threshold.

[0082] The ratio analysis module is used to acquire real-time operating condition data of the boiler furnace when the real-time removal rate data meets the preset removal rate threshold, match the real-time operating condition data with the emission flue gas concentration data, and calculate the waste gas co-firing ratio adjustment command.

[0083] The waste gas treatment module is used to adjust the inlet flow rate of the waste gas inlet pipe according to the waste gas co-firing ratio adjustment command, obtain the adjusted waste gas flow rate, and introduce it into the boiler furnace for co-firing treatment.

[0084] The leakage monitoring module is used to acquire the opening status data and opening degree data of the induction shut-off valve on the emergency venting pipe in real time, and calculate the sealing leakage rate data.

[0085] The control and processing module is used to control the inductive shut-off valve to switch to the fully open state when the sealing leakage rate data exceeds the preset leakage threshold or when a boiler shutdown status signal is received, so as to guide the exhaust gas flow into the emergency vent pipe for emergency discharge treatment.

[0086] The associated storage module is used to associate and store initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and seal leakage rate data.

[0087] Example The implementation entity in this embodiment is the factory's central control system, referred to as the system. Its core is a high-performance industrial server running configuration software and a real-time database. The system connects to various key devices via industrial Ethernet. An online gas chromatograph (GC) is installed on the waste gas collection pipeline of the coal mill, with its sampling probe located at a designated sampling point. The GC analyzes the waste gas sample every 5 minutes and outputs the TVOC concentration value. The unit is mg / m³, and it is uploaded to the system via the Modbus TCP protocol.

[0088] A continuous emission monitoring system (CEMS) is installed at the monitoring point on the boiler tail chimney. Its non-methane total hydrocarbon (FID) analyzer and methanol (FTIR) analyzer output a set of data every 10 seconds. and Data, in units of mg / m³, is uploaded to the system via a data acquisition device.

[0089] The total combustion air volume is read in real time from the boiler DCS via the OPC protocol. Real-time operating data such as furnace temperature and main coal feed rate are collected. Mass flow meters are installed on the main exhaust gas pipeline and emergency vent pipe to measure the total exhaust gas flow rate. And monitor potential leaks in flow.

[0090] The intake regulating valve of the main exhaust gas pipeline and the induction shut-off valve of the emergency vent pipe are equipped with intelligent electric actuators and built-in valve position transmitters. Both receive 4-20mA control commands from the system and transmit their valve position opening data. Feedback is sent to the system.

[0091] The specific implementation method is as follows: Step S1: Data Synchronization Acquisition and Preprocessing: The system is set to a 2-second synchronous scan cycle. Within each cycle: Get the latest from GC The data is stored every 5 minutes, and the system caches and uses the latest values.

[0092] Real-time data acquisition from CEMS data acquisition instrument and data.

[0093] Real-time data acquisition from boiler DCS Furnace temperature.

[0094] Get real-time data from the flow meter .

[0095] Obtain valve position opening data from the induction shut-off valve. .

[0096] All data is formatted and cached after being stamped with the same timestamp.

[0097] Step S2: Real-time removal rate calculation and judgment: The system performs a calculation every 10 seconds, with the cycle synchronized with the CEMS data cycle. According to the formula Calculate real-time removal rate data .

[0098] Will Compared to the preset removal rate threshold of 99%. If If the condition is met, the system is deemed to "satisfy" and proceeds to step S3; otherwise, the system triggers a "low removal rate" alarm and records the event log.

[0099] Step S3: Generate an instruction to adjust the waste gas co-firing ratio: when At that time, the combustion optimization control loop is activated: Search Condition Comparison Table: A two-dimensional lookup table is pre-stored in system memory, with its row index as follows: The concentration range, such as <20, 20-40, >40 mg / m³, is indicated by the column index. The concentration range is specified, such as <30, 30-50, >50 mg / m³, with the cross cells representing the corresponding target waste gas co-firing ratio correction values. ,For example:( 20-40 :30-50)-> .

[0100] Calculate the target flow: The system obtains the result from a table lookup. Based on the current total combustion air volume Calculate the new target exhaust gas flow rate For example, if the current exhaust gas flow rate accounts for 3% of the total air volume, The new target combustion wind ratio , .

[0101] Generate control commands: The system will Compared with current actual measurements The deviation is input into the proportional-integral-derivative (PID) controller algorithm to obtain the exhaust gas co-firing ratio adjustment command, which is a 4-20mA analog signal value, and is directly sent to the actuator of the exhaust gas intake regulating valve.

[0102] The principle of the proportional-integral-derivative (PID) controller algorithm is: to calculate the target exhaust gas flow rate... As the set value, the current exhaust gas flow rate measured by the flow meter will be used. As feedback, the error between the two is calculated in real time. Then, proportional, integral, and differential operations are performed on this error signal, and the three calculation results are superimposed to synthesize a control signal capable of dynamically eliminating the error. Finally, the system converts this control signal into a 4-20mA analog current value, which is sent to the intake regulating valve as a command to adjust the waste gas co-firing ratio. By adjusting the valve opening in real time, the actual waste gas flow rate quickly and smoothly follows the target value, thereby ensuring the stability of the boiler co-firing operation and compliance with emission concentration standards.

[0103] Step S4: Waste gas co-firing execution: The intake regulating valve linearly adjusts its opening degree according to the received 4-20mA command, thereby changing the flow rate of the exhaust gas. This exhaust gas flow is directed to a dedicated interface of the boiler's secondary air box and injected into the furnace as secondary air, where it is fully mixed and burned with the pulverized coal flame in the high-temperature zone at the center of the furnace, which is approximately 950°C.

[0104] Step S5: Safety Sealing Monitoring The system performs a leak rate diagnosis every minute, including the following steps: Read the feedback valve position of the inductive shut-off valve on the emergency vent pipe. Under normal conditions, when the system has not issued an opening command, the valve should be in the fully closed position. .

[0105] If the feedback valve position If the valve is not completely closed, then the valve characteristic curve function is called. Calculate the real-time overflow flow. ,in This represents the pipeline pressure differential, which is read by a pressure transmitter.

[0106] Valve characteristic curves are obtained directly from the technical documents or product manuals provided by the valve manufacturer. These documents contain leakage curves or flow characteristic data tables obtained from standard tests conducted on that valve model before it leaves the factory, showing the relationship between leakage and flow rate at specific opening degrees and pressure differentials.

[0107] According to the formula Calculate seal leakage rate data .

[0108] Step S6: Interlocking control of emergency emissions: The system continuously monitors two conditions; if either condition is triggered, an emergency switchover will be executed: Condition A concerns leakage exceeding the limit: When At that moment, the system immediately: a. A red alarm window pops up on the large screen in the control room, and a voice prompt says "Emergency vent valve leakage exceeds the standard".

[0109] b. Send a "lock" command to the exhaust gas intake regulating valve to freeze its opening at the current value and block subsequent adjustment commands.

[0110] c. Send an "open" command to the induction shut-off valve.

[0111] Condition B pertains to boiler shutdown: The system monitors the "Main fuel valve closed" digital signal sent by the boiler DCS in real time. Upon receiving this boiler shutdown status signal, the system immediately executes interlocking actions: a. Send a "0% opening" command (fully closed) to the exhaust gas intake regulating valve.

[0112] b. Send a “100% opening” command (fully open) to the emergency vent pipe inductive shut-off valve.

[0113] c. Monitor the feedback signals from both valves to confirm the switching is complete. At this point, all coal mill exhaust gas is directly discharged through the emergency vent pipe.

[0114] Step S7: Data Association Storage and Archiving: The system will collect all raw data and intermediate calculation data. Control commands, alarm events, and their corresponding timestamps are written to the OSIsoftPISystem real-time database in real time as data records.

[0115] The database administrator configured a data archiving policy: in the PI archive file, all data points related to this process are set to be retained for 5 years. The system automatically performs data compression and long-term storage; data older than 5 years will be automatically deleted to ensure that storage complies with regulatory requirements.

[0116] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0117] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0118] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0119] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0120] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0121] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for treating VOC waste gas in chemical plants by co-firing it in a boiler, characterized in that, Includes the following steps: Acquire the initial exhaust gas concentration data collected from the exhaust gas sampling point, and acquire the emission flue gas concentration data collected from the boiler tail flue monitoring point; Based on the initial exhaust gas concentration data and the emission flue gas concentration data, the real-time removal rate data is calculated, and it is determined whether the real-time removal rate data meets the preset removal rate threshold. When the real-time removal rate data meets the preset removal rate threshold, the real-time operating condition data of the boiler furnace is obtained, and the real-time operating condition data is matched with the emission flue gas concentration data to calculate the waste gas co-firing ratio adjustment command. According to the waste gas co-firing ratio adjustment instruction, the inlet flow rate of the waste gas access pipeline is adjusted to obtain the adjusted waste gas flow rate and introduce it into the boiler furnace for co-firing treatment. Real-time acquisition of the opening status and opening degree data of the induction shut-off valve on the emergency vent pipe, and calculation of the sealing leakage rate data; When the sealing leakage rate exceeds the preset leakage threshold, or when a boiler shutdown signal is received, the control sensor shut-off valve is switched to the fully open state to guide the exhaust gas flow into the emergency vent pipe for emergency discharge treatment. The initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and seal leakage rate data are stored together.

2. The method for treating VOC waste gas in chemical plants by co-firing with boilers as described in claim 1, characterized in that, The acquisition of initial exhaust gas concentration data collected from exhaust gas sampling points and exhaust gas concentration data collected from boiler tail flue monitoring points includes: The mass concentration of volatile organic compounds in the waste gas to be treated was obtained by setting sampling points on the waste gas collection pipeline of the coal mill, which served as the initial waste gas concentration data. Data on the concentration of non-methane total hydrocarbons and methanol in the flue gas after combustion are obtained through online monitoring instruments and used as emission flue gas concentration data.

3. The method for treating VOC waste gas in chemical plants by co-firing in boilers as described in claim 1, characterized in that, The real-time removal rate data is calculated based on the initial exhaust gas concentration data and the emission flue gas concentration data, including: The initial exhaust gas concentration data is used as the denominator, and the difference between the initial exhaust gas concentration data and the emission flue gas concentration data is used as the numerator to calculate the percentage value. This percentage value is defined as the real-time removal rate data.

4. The method for treating VOC waste gas in chemical plants by co-firing in boilers as described in claim 1, characterized in that, The step of matching real-time operating condition data with emission flue gas concentration data to calculate the waste gas co-firing ratio adjustment instruction includes: Based on the real-time values ​​of non-methane total hydrocarbons and methanol in the flue gas concentration data, a preset operating condition comparison table is retrieved to determine the corresponding target combustion air ratio. The target combustion air ratio is compared with the current air volume in the real-time operating data to generate an electrical signal for driving the damper actuator to move. The electrical signal is the exhaust gas co-combustion ratio adjustment command.

5. The method for treating VOC waste gas in chemical plants by co-firing with boilers as described in claim 1, characterized in that, The real-time acquisition of the opening status and opening degree data of the inductive shut-off valve on the emergency vent pipe, and the calculation of the sealing leakage rate data, includes: The valve stem displacement sensor value of the inductive shut-off valve in the closed command state is collected as the opening data; The preset mapping curve between valve opening and fluid flow rate is retrieved, and the real-time overflow flow rate is calculated by combining the opening data. The real-time overflow flow rate is compared with the total exhaust gas flow rate to obtain the seal leakage rate data.

6. The method for treating VOC waste gas in chemical plants by co-firing in boilers as described in claim 5, characterized in that, The sealing leakage rate data is used for interlocking control of the induction shut-off valve, including: When the seal leakage rate data is within the preset range, maintain the current state of the inductive shut-off valve; When the seal leakage rate exceeds the preset leakage threshold, the system triggers an alarm signal and blocks the exhaust gas co-firing ratio adjustment command.

7. The method for treating VOC waste gas in chemical plants by co-firing in boilers as described in claim 1, characterized in that, The process of directing the exhaust gas flow into the emergency vent pipe for emergency discharge treatment includes: Receive the cut-off signal from the boiler's main fuel supply system as the boiler shutdown status signal; Based on the boiler shutdown status signal, the actuator drives the inlet valve of the exhaust gas inlet pipe to close and drives the induction shut-off valve to open to the maximum stroke position.

8. The method for treating VOC waste gas in chemical plants by co-firing in boilers as described in claim 1, characterized in that, The process of associating and storing initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and seal leakage rate data includes: The initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and sealing leakage rate data are packaged into data packets according to timestamp information and stored in the historical database. Set the automatic cleanup cycle for the historical database to ensure that the data packets are retained for the maximum preset time period.

9. The method for treating VOC waste gas in chemical plants by co-firing with boilers as described in claim 1, characterized in that, After the real-time removal rate data and the sealing leakage rate data are correlated and stored, the process further includes: introducing the adjusted exhaust gas flow into the boiler furnace for co-firing treatment, including: The exhaust gas flow is transported through pipelines to the secondary air nozzle of the boiler; Alternatively, the exhaust gas stream can be mixed with the main combustion air and then introduced into the furnace through the combustion air duct.

10. A co-firing system for treating VOC waste gas in a chemical plant, used to implement the co-firing method for treating VOC waste gas in a chemical plant as described in any one of claims 1-9, characterized in that, include: Data acquisition module, real-time judgment module, proportional analysis module, exhaust gas treatment module, leak monitoring module, control and processing module, and associated storage module; The data acquisition module is used to acquire the initial exhaust gas concentration data collected from the exhaust gas sampling point and the emission flue gas concentration data collected from the boiler tail flue monitoring point. The real-time judgment module is used to calculate the real-time removal rate data based on the initial exhaust gas concentration data and the emission flue gas concentration data, and to determine whether the real-time removal rate data meets the preset removal rate threshold. The ratio analysis module is used to obtain the real-time operating condition data of the boiler furnace when the real-time removal rate data meets the preset removal rate threshold, and to match the real-time operating condition data with the emission flue gas concentration data to calculate the waste gas co-firing ratio adjustment command. The waste gas treatment module is used to adjust the inlet flow rate of the waste gas inlet pipe according to the waste gas co-firing ratio adjustment command, obtain the adjusted waste gas flow rate and introduce it into the boiler furnace for co-firing treatment. The leakage monitoring module is used to acquire the opening status data and opening degree data of the induction shut-off valve on the emergency venting pipe in real time, and calculate the sealing leakage rate data. The control and processing module is used to control the inductive shut-off valve to switch to the fully open state when the sealing leakage rate data exceeds the preset leakage threshold or when a boiler shutdown status signal is received, so as to guide the exhaust gas flow into the emergency vent pipe for emergency discharge treatment. The associated storage module is used to associate and store initial exhaust gas concentration data, emission flue gas concentration data, real-time removal rate data, and seal leakage rate data.

Images