Converter gas complex tidal flow-based heat value pushing calculation method

Abstract

The application discloses a heat value calculation method based on converter gas complex tide flow, comprising the following steps: collecting heat value data of converter gas pipe network entrance, and pressure, flow and temperature data of converter gas pipe network entrance and mixing station; real-time data cleaning of heat value data; constructing a system network mathematical model according to the physical structure of the converter gas pipe network system, dividing all possible working conditions in system operation, and realizing real-time judgment of system working conditions; constructing a tide flow equation of the converter gas pipe network system according to the flow continuity and mass conservation equation of fluid, and combining the real-time collected pressure, flow and temperature data to perform tide flow calculation on the converter gas pipe network system; and based on the calculation result of the tide flow equation and the heat value data of the outlet of the pressure booster unit, the heat value of each mixing station is calculated in real time. The method can realize real-time calculation of the heat value of each pipe network node in the converter gas pipe network system.

Description

Technical Field

[0001] This invention relates to the field of information technology, and specifically to a method for calculating the calorific value shift based on the complex flow of converter gas. Background Technology

[0002] As the steel industry is a high-energy-consuming industry, it has always faced the challenge of optimizing energy conservation and consumption reduction. In steel production, converter gas is an important secondary energy source, directly applied in various stages of production. However, due to the fluctuating calorific value of converter gas, typically ranging from 6200 to 8100 kJ / Nm3, the calorific value of the mixed gas fluctuates, impacting the production of gas users. This is undoubtedly uneconomical for energy-intensive production processes. To mitigate the impact of converter gas calorific value fluctuations on gas users and improve the combustion stability of power plant gas turbine units, real-time monitoring of the calorific value of each node in the converter gas pipeline system is necessary. However, due to the structural design of the converter gas pipeline system, the number of calorific value meters that can be installed is very limited, making it impossible to simultaneously monitor all pipeline nodes. Therefore, a new method for calculating the calorific value shift of the converter gas pipeline system is urgently needed. This method requires only collecting the calorific values ​​of a limited number of nodes and performing real-time shift calculations to obtain the calorific value of each node in the converter gas pipeline system in real time.

[0003] Chinese patent document with application number 202010869154.X discloses a mixed gas calorific value monitoring system and method. According to its specification, this method can calculate the calorific value of each mixed gas user in real time, realizing the calorific value detection of the entire mixed gas pipeline network system. However, this method calculates the calorific value of the mixed gas by iteratively solving the equation using the finite volume method. This solution process requires reasonable boundary conditions. However, due to the complexity of actual industrial site conditions, poor data quality, and inaccurate pipeline parameters, the calculation model of this method is prone to non-convergence, failing to obtain accurate calorific value results, thus causing even greater problems. Furthermore, this method does not consider the complex operating conditions caused by gas pipeline networks with multiple gas source nodes, resulting in low stability in practical applications. It is only suitable for simulation and difficult to apply effectively.

[0004] Chinese patent document with application number 201811547957.2 discloses a soft measurement method for the calorific value of gas under the condition of co-firing blast furnace gas and converter gas. According to the description, the method obtains the air flow rate and gas flow rate by solving the heat exchange parameters of the air preheater and gas preheater, and identifies the calorific value of blast furnace gas and converter gas by combining the relationship between the calorific value of gas and the air volume. This realizes the soft measurement of the calorific value of gas in boilers with co-firing blast furnace gas and converter gas, and solves the inconvenience and difficulties caused by the fact that most steel plants do not have online gas calorific value analyzers in their combustion equipment. However, this method requires the relevant data to be collected by the combustion system after the gas is burned before the calculation can be performed. It cannot pre-calculate the calorific value of converter gas before the two types of gas are mixed, and cannot provide effective calorific value data for gas dispatchers in advance. This results in insufficient preparation and time for operation to adjust the gas ratio, and it is impossible to accurately and stably control the calorific value of the mixed gas. Summary of the Invention

[0005] The purpose of this invention is to provide a method for calculating the calorific value shift based on the complex flow of converter gas. This method can use calorific value data measured by a limited number of calorimeters to perform real-time calculations on the calorific value of each node in the converter gas pipeline system. The calculation results enable gas dispatchers to adjust the gas ratio in a timely and accurate manner, control the stability of the calorific value of the mixed gas, and better assist gas dispatchers in balancing and optimizing the steel energy system.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for calculating calorific value shift based on complex converter gas flow includes the following steps:

[0008] Step 1: Install a calorific value meter at the inlet of the compressor unit of the converter gas pipeline network system to collect the calorific value data of the converter gas. Install pressure sensors, flow sensors and temperature sensors at the outlet of the compressor unit and the mixing station of the converter gas pipeline network system to collect the pressure data, flow data and temperature data of the converter gas in real time.

[0009] Step 2: The calorific value data obtained in Step 1 is cleaned in real time using the moving average method to obtain preprocessed calorific value data;

[0010] Step 3: Construct a mathematical model of the converter gas pipeline network based on the physical structure of the converter gas pipeline network system. Then, based on the network structure of the mathematical model, divide all possible operating conditions in the system operation and make real-time judgments on the current operating conditions of the converter gas pipeline network system.

[0011] Step 4: Based on the physical structure and all operating conditions of the converter gas pipeline system, construct the corresponding power flow equations for each operating condition according to the fluid flow continuity and mass conservation equations. The specific power flow equations are as follows:

[0012]

[0013]

[0014]

[0015] Among them, Q n Expressed as gas flow rate under standard conditions, in meters per second (m³). 3 / s, P n The pressure is expressed as pressure under standard conditions, in Pa. P represents the current pressure, also in Pa. T n Temperature is expressed as a temperature under standard conditions, in Kelvin (K) and temperature (T). t The current temperature is expressed in Kelvin (K), w represents the gas flow velocity in m / s, and A represents the cross-sectional area of ​​the pipe in m³. 2 D represents the diameter of the pipe, ρ n The density of a gas under standard conditions is expressed in kg / m³. 3 ρ represents the current gas density, with units of kg / m³. 3 ;

[0016] Formula 1 is the flow continuity equation, which considers the influence of pressure and temperature changes in the converter gas pipeline system on the flow rate changes within the pipeline. Since the flow rate of a converter gas pipeline system is continuous, the time delay t for the flow rate to pass through the converter gas pipeline system can be approximately calculated. i Formula 3 is the mass conservation equation, meaning the mass of a system remains constant. Combining the aforementioned power flow equation with real-time collected pressure, flow, and temperature data, the time delay t required for the flow rate at the compressor outlet of the converter gas pipeline system to reach each mixing station or flow convergence point under various operating conditions can be calculated. i ;

[0017] Step 5: Based on the assessment of the current operating condition of the converter gas pipeline system in Step 3, two calculation modes are set up to construct a calorific value shift calculation model. The two calculation modes are as follows:

[0018] Calculation Mode 1: Based on the judgment of the current operating condition of the converter gas pipeline system in Step 3, if the calculated mixing station is supplied with gas by a single compressor unit, then the delay time t calculated in Step 4 is used. iThe preprocessed calorific value data obtained in step two is used to calculate the corresponding mixed site in the first t. i The calorific value data at any given time is the calorific value of the converter gas at the mixing station at that current time;

[0019] Calculation Mode Two: Based on the judgment of the current operating condition of the converter gas pipeline system in Step Three, if the calculated mixing station is supplied with gas by multiple compressor units, the gas received by the multiple mixing stations will be pre-mixed at different flow convergence points under different operating conditions. Therefore, it is necessary to determine the flow convergence point of the converter gas based on the current operating condition of the converter gas pipeline system, and then use the delay time t calculated in Step Four. i Using the flow rate data at the outlet of the compressor unit obtained in step one, the flow convergence point at the corresponding t-th point can be calculated. i Traffic data at any time Then the newly obtained traffic data Input the power flow equations and calculate the first t. i Time delay Then, based on the newly obtained first t... i Time delay Using the preprocessed calorific value data obtained in step two, the flow convergence point in the first t is calculated. i Heat value data at any time Finally, Formula 4 is used to calculate the flow convergence point in the first t. i Heat value data at any time The calorific value data This refers to the calorific value of the converter gas at the current mixing station, and Formula 4 is: H = ∑G i H i In this context, Formula 4 represents the formula for calculating the calorific value of a combustible gas mixture, where H represents the calorific value of the combustible gas mixture. i Let G represent the calorific value of the i-th combustible gas. i Let G represent the volume concentration of the i-th combustible gas, and let the sum of the proportions of all types of gas equal 1, i.e., ∑G i =1.

[0020] Preferably, in step two, the data cleaning steps are as follows: first, a threshold needs to be set to determine whether the collected calorific value data deviates from the normal working value, and then the data that deviates from the normal working value is corrected and supplemented by the moving average method.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. This method can utilize the calorific value data measured by a limited number of calorimeters, combined with the pressure, temperature, and flow data measured at each pipeline node, to realize real-time shift calculation of the calorific value of each pipeline node in the converter gas pipeline system. The calorific value shift calculation results enable gas dispatchers to adjust the gas ratio in a timely and accurate manner, control the stability of the calorific value of the mixed gas, and better assist gas dispatchers in the balance optimization of the steel energy system.

[0023] 2. This method constructs the power flow equation of the converter gas pipeline system through data cleaning and actual system operating condition division, and establishes a calorific value shift calculation model. When applied in actual industrial field, the calorific value shift calculation model can stably and in real time calculate the current calorific value of converter gas at each pipeline node in the converter gas pipeline system, thus solving the stability and accuracy problems of the existing model in actual application calculation. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for calculating the calorific value shift based on the complex flow of converter gas according to the present invention.

[0025] Figure 2 This is a structural diagram of the converter gas pipeline system in Embodiment 1 of the present invention.

[0026] Figure 3 This is a structural diagram of the converter gas pipeline system in Embodiment 2 of the present invention.

[0027] Figure 4 This is a graph showing the calorific value data measured by the calorific value meter at the pressurization unit in Embodiment 2 of the present invention over a 60-minute period.

[0028] Figure 5 This is a graph showing the calculated heat value shift of the mixed site 4 in Embodiment 2 of the present invention over a 60-minute period.

[0029] Figure 6 This is a curve comparison of the results of solving the calorific value of the mixed site 4 over a 60-minute time period using the traditional method and the proposed method in Embodiment 2 of this invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] C-calorific value meter;

[0032] PA, PB, P1, P2, P3, P4, P5, P6, P7, P8, P9 - Pressure sensors;

[0033] QA, QB, Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9 - Flow sensors;

[0034] TA, TB, T1, T2, T3, T4, T5, T6, T7, T8, T9 - Temperature sensors;

[0035] J1, J2, J3 - Traffic convergence points. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will now be described with reference to the accompanying drawings.

[0037] Example 1

[0038] Please refer to Figure 1 and Figure 2 , Figure 2 This embodiment is a simplified design diagram of a conventional converter gas pipeline network structure and sensor arrangement. Figure 2 The converter gas pipeline system shown is used to describe the application principle of this method.

[0039] A method for calculating calorific value shift based on complex converter gas flow includes the following steps:

[0040] Step 1: Using the calorimeter C installed at the inlet of the converter gas pipeline system (i.e., at the inlet of compressor unit 1 and compressor unit 2) and the flow sensors PA and PB installed at the outlets of compressor unit 1 and compressor unit 2 respectively, collect data from the current time to the previous T at the outlets of compressor unit 1 and compressor unit 2. i The calorific value data and flow rate data at different times are given. The calorific value data can be represented as {H(1), H(2), ..., H(T)}. i The traffic data can be represented as {f(1), f(2), ..., f(T)}, where f(t) is the sum of the two data points. i / n)}, where n represents the sampling frequency;

[0041] Step 2: The calorific value data obtained in Step 1 is cleaned in real time using the moving average method to obtain preprocessed calorific value data;

[0042] It should be noted that because the calorimeter C itself has a backflushing phenomenon, the calorimeter data may drop to 0 in stages, resulting in abnormal data. Therefore, the calorimeter data needs to be cleaned in real time using the moving average method. Specifically, a threshold needs to be set to determine whether the collected calorimeter data deviates from the normal operating value. Then, the moving average method is used to correct and supplement the data that deviates from the normal operating value, so as to realize the real-time data cleaning of the calorimeter gas pipeline system and ensure that the subsequent model calculation will not have calculation errors due to data loss.

[0043] Step 3: Construct a mathematical model of the converter gas pipeline network based on the physical structure of the converter gas pipeline network system. Then, based on the network structure of the mathematical model, divide all possible operating conditions in the system operation and make real-time judgments on the current operating conditions of the converter gas pipeline network system.

[0044] It should be noted that because the converter gas pipeline system contains multiple gas source nodes, it will experience various operating conditions during actual operation. Within the same pipeline section, fluid will flow in both forward and reverse directions. Based on the physical structure of the converter gas pipeline system, the flow convergence points J1, J2, ... J... can be identified. k The direction of gas flow, k represents the number of flow intersection points, and thus divides into several different working conditions;

[0045] The specific operating conditions of converter gas pipeline systems with different complex designs vary. The following will combine... Figure 2 The converter gas pipeline system shown is used to illustrate the division of operating conditions, which can be divided into:

[0046] Operating Condition 1: Unit 1 and Unit 2 can jointly provide flow to Mixed Site 1 and Mixed Site 2;

[0047] Operating Condition 2: Unit 1 and Unit 2 can jointly provide flow to Mixed Site 3;

[0048] Operating Condition 3: Unit 1 and Unit 2 can jointly provide flow to mixed site 4 and mixed site 5;

[0049] After the operating conditions are defined, the flow rate and gas flow direction at the flow intersection points J1, J2, and J3 can be determined by real-time collected flow data, thereby determining the current operating conditions of the converter gas pipeline system.

[0050] Step 4: Based on the physical structure of the converter gas pipeline system and the three operating conditions defined in Step 3, and according to the fluid flow continuity and mass conservation equations, construct the corresponding power flow equations for the converter gas pipeline system under each operating condition. The specific power flow equations are as follows:

[0051]

[0052]

[0053]

[0054] Among them, Q n Expressed as gas flow rate under standard conditions, in meters per second (m³). 3 / s, P nThe pressure is expressed as pressure under standard conditions, in Pa. P represents the current pressure, also in Pa. T n Temperature is expressed as a temperature under standard conditions, in Kelvin (K) and temperature (T). t The current temperature is expressed in Kelvin (K), w represents the gas flow velocity in m / s, and A represents the cross-sectional area of ​​the pipe in m³. 2 D represents the diameter of the pipe, ρ n The density of a gas under standard conditions is expressed in kg / m³. 3 ρ represents the current gas density, with units of kg / m³. 3 ;

[0055] Formula 1 is the flow continuity equation, which considers the influence of pressure and temperature changes in the converter gas pipeline system on the flow rate changes within the pipeline. Since the flow rate of a converter gas pipeline system is continuous, the time delay t for the flow rate to pass through the converter gas pipeline system can be approximately calculated. i Formula 3 is the mass conservation equation, meaning the mass of a system remains constant. Using the power flow equations of the converter gas pipeline system constructed under different operating conditions, and by collecting real-time pressure, flow, and temperature data at the outlets of compressor units 1 and 2, and at various mixing stations, the following can be stably solved: the time delay t required for the flow rate at the outlets of the two compressor units (i.e., compressor units 1 and 2) of the converter gas pipeline system to reach various mixing stations or flow convergence points under various operating conditions. i .

[0056] Step 5: Based on the assessment of the current operating condition of the converter gas pipeline system in Step 3, two calculation modes are set up to construct a calorific value shift calculation model. The two calculation modes are as follows:

[0057] Calculation Mode 1: Based on the judgment of the current operating condition of the converter gas pipeline system in Step 3, if the calculated mixing station is supplied with gas by a single compressor unit, then the delay time t calculated in Step 4 is used. i The preprocessed calorific value data obtained in step two is used to calculate the corresponding mixed site in the first t. i The calorific value data at any given time is the calorific value of the converter gas at the mixing station at that current time;

[0058] Calculation Mode Two: Based on the judgment of the current operating condition of the converter gas pipeline system in Step Three, if the calculated mixing station is supplied with gas by multiple compressor units, since the gas received by multiple mixing stations will be pre-mixed at different flow convergence points under different operating conditions, it is necessary to determine the flow convergence point of the converter gas as J based on the current operating condition of the converter gas pipeline system.s s represents 1, 2, or 3, and then the delay time t is calculated according to step four. i Using the flow rate data at the outlet of the compressor unit obtained in step one, the flow convergence point J is calculated accordingly. s In the corresponding first t i Traffic data at any time Then the newly obtained traffic data Input the power flow equations and calculate the first t. i Time delay Then, based on the newly obtained first t... i Time delay Using the preprocessed calorific value data obtained in step two, the flow convergence point J is calculated accordingly. s In the first t i Heat value data at any time Finally, the flow intersection point J is calculated using Formula 4. s In the first t i Heat value data at any time The calorific value data This refers to the calorific value of the converter gas at the current mixing station, and Formula 4 is: H = ∑G i H i In this context, Formula 4 represents the formula for calculating the calorific value of a combustible gas mixture, where H represents the calorific value of the combustible gas mixture. i Let G represent the calorific value of the i-th combustible gas. i Let G represent the volume concentration of the i-th combustible gas, and let the sum of the proportions of all types of gas equal 1, i.e., ∑G i =1.

[0059] Based on the real-time shift calculation of the power flow equations described in this method, the calorific value of each pipeline node (i.e., flow convergence point and mixing station) of the converter gas pipeline network system at the current moment can be calculated. In the calculation process of this embodiment, only one calorimeter C is used, without the need to set up a large number of calorimeters, which reduces the investment cost. Compared with the prior art, the power flow equations based on steady-state conditions ensure the stable operation of the model and will not cause the model calculation non-convergence problem due to the complexity of actual working conditions and the influence of parameter noise.

[0060] Example 2

[0061] Please refer to Figure 3 , Figure 3 This is a simplified design diagram of the converter gas pipeline network structure and sensor layout for a steel plant in China. The converter gas pipeline network system includes two compressor units, nine gas mixing stations, and three flow convergence points. This embodiment will combine... Figure 3The converter gas pipeline system shown is used to illustrate the computational application case of this method and the differences between it and the traditional method for solving calorific value.

[0062] Please refer to Figure 3 , Figure 4 , Figure 5 and Figure 6 , Figure 4 , Figure 5 , Figure 6 These correspond to the actual calorific value data measured by calorific value meter C at the pressurization unit during a specific 60-minute period on a certain day, the calculated calorific value shift of converter gas at mixing station 4 based on this invention, and the comparison results of the calorific value after mixing gas at mixing station 4 based on the traditional method and this method. For example... Figure 6 As shown, the target calorific value of the mixed gas is 4000 kJ / Nm³. 3 Based on traditional methods, its default calorific value for blast furnace gas is 3300 kJ / Nm³. 3 The calorific value of converter gas is 7200 kJ / Nm³. 3 According to Formula 4, the proportions of the two gases can be calculated as follows: blast furnace gas 0.82 and converter gas 0.18. Calculating the calorific value of the mixed gas using a fixed proportion results in a significant deviation from the target calorific value. However, this method can estimate the calorific value of the converter gas before mixing at the mixing site through a shift calculation, and calculate the dynamic proportions of the two gases in real time according to Formula 4, making the mixing proportions more accurate and ensuring that the calorific value of the mixed gas is closer to the target calorific value. The above practical application case verifies the effectiveness of this method.

Claims

1. A method for calculating calorific value shift based on complex converter gas flow, characterized in that: Includes the following steps: Step 1: Install a calorific value meter at the inlet of the compressor unit of the converter gas pipeline network system to collect the calorific value data of the converter gas. Install pressure sensors, flow sensors and temperature sensors at the outlet of the compressor unit and the mixing station of the converter gas pipeline network system to collect the pressure data, flow data and temperature data of the converter gas in real time. Step 2: The calorific value data obtained in Step 1 is cleaned in real time using the moving average method to obtain preprocessed calorific value data; Step 3: Construct a mathematical model of the converter gas pipeline network based on the physical structure of the converter gas pipeline network system. Then, based on the network structure of the mathematical model, divide all possible operating conditions in the system operation and make real-time judgments on the current operating conditions of the converter gas pipeline network system. Step 4: Based on the physical structure and all operating conditions of the converter gas pipeline system, construct the corresponding power flow equations for each operating condition according to the fluid flow continuity and mass conservation equations. The specific power flow equations are as follows: Among them, Q n Expressed as gas flow rate under standard conditions, in meters per second (m³). 3 / s, P n The pressure is expressed as pressure under standard conditions, in Pa. P represents the current pressure, also in Pa. T n Temperature is expressed as a temperature under standard conditions, in Kelvin (K) and temperature (T). t The current temperature is expressed in Kelvin (K), w represents the gas flow velocity in m / s, and A represents the cross-sectional area of ​​the pipe in m³. 2 D represents the diameter of the pipe, ρ n The density of a gas under standard conditions is expressed in kg / m³. 3 ρ represents the current gas density, with units of kg / m³. 3 ; Formula 1 is the flow continuity equation, which considers the influence of pressure and temperature changes in the converter gas pipeline system on the flow rate changes within the pipeline. Since the flow rate of a converter gas pipeline system is continuous, the time delay t for the flow rate to pass through the converter gas pipeline system can be approximately calculated. i Formula 3 is the mass conservation equation, meaning the mass of a system remains constant. Combining the aforementioned power flow equation with real-time collected pressure, flow, and temperature data, the time delay t required for the flow rate at the compressor outlet of the converter gas pipeline system to reach each mixing station or flow convergence point under various operating conditions can be calculated. i ; Step 5: Based on the assessment of the current operating condition of the converter gas pipeline system in Step 3, two calculation modes are set up to construct a calorific value shift calculation model. The two calculation modes are as follows: Calculation Mode 1: Based on the judgment of the current operating condition of the converter gas pipeline system in Step 3, if the calculated mixing station is supplied with gas by a single compressor unit, then the delay time t calculated in Step 4 is used. i The preprocessed calorific value data obtained in step two is used to calculate the corresponding mixed site in the first t. i The calorific value data at a given moment is the calorific value of the converter gas at the current mixing station. Calculation Mode Two: Based on the judgment of the current operating condition of the converter gas pipeline system in Step Three, if the calculated mixing station is supplied with gas by multiple compressor units, the gas received by these multiple mixing stations will be pre-mixed at different flow convergence points under different operating conditions. Therefore, it is necessary to determine the flow convergence point of the converter gas based on the current operating condition of the converter gas pipeline system, and then use the delay time t calculated in Step Four. i Using the flow rate data at the outlet of the compressor unit obtained in step one, the flow convergence point at the corresponding t-th point can be calculated. i Traffic data at any time Then the newly obtained traffic data Input the power flow equations and calculate the first t. i Time delay Then, based on the newly obtained first t... i Time delay Using the preprocessed calorific value data obtained in step two, the flow convergence point in the first t is calculated. i Heat value data at any time Finally, Formula 4 is used to calculate the flow convergence point in the first t. i Heat value data at any time The calorific value data This refers to the calorific value of the converter gas at the current mixing station, and Formula 4 is: H = ∑G i H i In this context, Formula 4 represents the formula for calculating the calorific value of a combustible gas mixture, where H represents the calorific value of the combustible gas mixture. i Let G represent the calorific value of the i-th combustible gas. i Let G represent the volume concentration of the i-th combustible gas, and let the sum of the proportions of all types of gas equal 1, i.e., ∑G i =1.

2. The method for calculating calorific value shift based on complex converter gas flow according to claim 1, characterized in that: In step two, the data cleaning process is as follows: First, a threshold needs to be set to determine whether the collected calorific value data deviates from the normal operating value. Then, the data that deviates from the normal operating value is corrected and supplemented using the moving average method.

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