Online measurement system and method for cylindrical chimney gas emissions based on multi-point detection

Abstract

The present invention discloses an online measurement system and method for gas emissions from cylindrical chimneys based on multi-point detection, belonging to the field of greenhouse gas monitoring technology. The system comprises: a flow field simulation module that simulates flow field data within a flue according to given conditions; m airflow sensors that obtain gas flow velocities within the chimney from different angles; a classification module that classifies and stores the simulation results of the flow field simulation module; the simulation categories include elliptical wind speed models and parallel wind speed models; and an execution module that performs detection in two ways based on the classification of the simulation results: in the first method, when the simulation result is an elliptical wind speed model, two airflow sensors with a mutual intersection are activated; in the second method, when the simulation result is a parallel wind speed model, n airflow sensors without a mutual intersection are activated; and a statistical module that calculates the chimney gas emissions based on the detection results of the execution module. The present invention can accurately and quickly obtain chimney gas emissions.

Description

Technical Field

[0001] The present invention belongs to the technical field of greenhouse gas monitoring, and in particular relates to an online metering system and method for gas emissions from a cylindrical chimney based on multi-point detection. Background Art

[0002] Greenhouse gases, as we all know, are gases in the atmosphere that absorb solar radiation reflected by the ground and re-emit it, such as water vapor, carbon dioxide, and most refrigerants. Their effect is to warm the Earth's surface, similar to how a greenhouse traps solar radiation and warms the air within. This warming effect of greenhouse gases is known as the "greenhouse effect." Water vapor (H2O), carbon dioxide (CO2), nitrous oxide (N2O), freons, and methane (CH4) are the main greenhouse gases in the Earth's atmosphere.

[0003] In recent years, with the rapid development of industry, the problem of global warming has become increasingly serious. Some scientists believe that the gases emitted by industrial chimneys are one of the components of greenhouse gases. In order to achieve sustainable development, accurate monitoring of gas emissions from chimneys of various enterprises has far-reaching guiding significance for achieving sustainable development in the future. Summary of the Invention

[0004] In order to solve the technical problems existing in the known technology, the present invention provides an online metering system and method for gas emissions from a cylindrical chimney based on multi-point detection, which can quickly and accurately obtain the gas emissions in the chimney.

[0005] The first object of the present invention is to provide an online metering system for gas emissions from a cylindrical chimney based on multi-point detection, comprising at least:

[0006] Flow field simulation module that simulates the flow field data in the flue according to given conditions;

[0007] m airflow sensors for obtaining the gas flow rate in the chimney from different angles; m is a natural number greater than 1;

[0008] A classification module for classifying and saving the simulation results of the flow field simulation module; the simulation categories include elliptical wind speed model and parallel wind speed model;

[0009] According to the classification of the simulation results, the execution module of the detection is executed in the following two ways: Method 1: when the simulation result is an elliptical wind speed model, two airflow sensors with a mutual intersection are activated; Method 2: when the simulation result is a parallel wind speed model, n airflow sensors without a mutual intersection are activated; n is a natural number greater than 1;

[0010] A statistical module that calculates the amount of chimney gas emissions based on the detection results of the execution module.

[0011] Furthermore, the statistical module includes a first statistical unit cooperating with the first method and a second statistical unit cooperating with the second method.

[0012] Furthermore, the execution process of the first statistical unit is:

[0013] Get the flow rates v1 and v2 detected by two airflow sensors;

[0014] Get the cross-sectional area of the chimney pipe cavity S = πR 2 ;

[0015] The first calculation formula is: Q=((v1*k1+v2*k2) / 2)*S; where k1 and k2 are weight coefficients corresponding to flow velocities v1 and v2.

[0016] Furthermore, the execution process of the second statistical unit is:

[0017] Obtain the flow rate detected by each airflow sensor;

[0018] The second calculation formula is: Where ki is the weight coefficient of the i-th channel, n is the logarithm of the airflow sensor, Si is the cross-sectional area measured by the i-th pair of airflow sensors,

[0019] Furthermore, the airflow sensor is an ultrasonic sensor, and the insertion depth of the probe of the ultrasonic sensor is automatically adjusted in the horizontal direction along the diameter direction of the flue.

[0020] A second object of the present invention is to provide an online measurement method for gas emissions from a cylindrical chimney based on multi-point detection, comprising at least:

[0021] S1. A simulation model for obtaining flow field data in the flue according to given conditions;

[0022] S2. Obtaining a category of the simulation model according to the simulation model; the simulation category includes an elliptical wind speed model and a parallel wind speed model;

[0023] S3. Select the execution mode of the execution module according to the type of simulation model;

[0024] S4. Calculate the chimney gas emission according to the detection data obtained by the execution method.

[0025] Furthermore, the execution method includes method 1, when the simulation result is an elliptical wind speed model, starting two airflow sensors with mutual intersection points; method 2, when the simulation result is a parallel wind speed model, starting n airflow sensors without mutual intersection points; n is a natural number greater than 1.

[0026] Furthermore, when the execution mode is mode 1, the chimney gas emission statistics process is as follows:

[0027] Get the flow velocities v1 and v2 detected by the two airflow sensors; k1 and k2 are the weight coefficients corresponding to the flow velocities v1 and v2;

[0028] Get the cross-sectional area of the chimney pipe cavity S = πR 2 , where R is the radius of the chimney pipe section;

[0029] The calculation formula is: Q = ((v1*k1+v2*k2) / 2)*S.

[0030] Furthermore, when the execution mode is mode 2, the chimney gas emission statistics process is as follows:

[0031] Obtain the flow rate detected by each airflow sensor;

[0032] The calculation formula is: Where ki is the weight coefficient of the i-th channel, n is the logarithm of the airflow sensor, Si is the cross-sectional area measured by the i-th pair of airflow sensors,

[0033] The advantages and positive effects of the present invention are:

[0034] The present invention can fully refer to the velocity distribution inside the cross section, the measurement result has high accuracy, and the emission amount of the gas in the chimney can be quickly obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a system block diagram of a preferred embodiment of the present invention;

[0036] Figure 2 This is an elliptical wind speed model diagram in a preferred embodiment of the present invention;

[0037] Figure 3 This is a parallel wind speed model diagram in a preferred embodiment of the present invention;

[0038] Figure 4 is a layout diagram of three sensors in a preferred embodiment of the present invention;

[0039] Figure 5 Schematic diagram of the layout of six sensors in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings:

[0041] See Figure 1, an online measurement system for cylindrical chimney gas emissions based on multi-point detection, comprising:

[0042] Flow field simulation module, simulating the flow field data in the flue according to given conditions;

[0043] An airflow sensor group, comprising m airflow sensors for obtaining the gas flow rate in the chimney from different angles; m is a natural number greater than 1;

[0044] A classification module, which classifies and saves the simulation results of the flow field simulation module; the simulation categories include elliptical wind speed model and parallel wind speed model;

[0045] The execution module performs detection in the following two ways according to the classification of the simulation results: the first way is to start two airflow sensors with a mutual intersection when the simulation result is an elliptical wind speed model; the second way is to start n airflow sensors without a mutual intersection when the simulation result is a parallel wind speed model; n is a natural number greater than 1;

[0046] The statistics module calculates the stack gas emissions based on the detection results of the execution module.

[0047] The statistical module mainly includes a first statistical unit that cooperates with method 1 and a second statistical unit that cooperates with method 2.

[0048] The execution process of the first statistical unit is:

[0049] Get the flow rates v1 and v2 detected by two airflow sensors;

[0050] Get the cross-sectional area of the chimney pipe cavity S = πR 2 ;

[0051] The first calculation formula is: Q=((v1*k1+v2*k2) / 2)*S.

[0052] The execution process of the second statistical unit is:

[0053] Obtain the flow rate detected by each airflow sensor;

[0054] The second calculation formula is: Where ki is the weight coefficient of the i-th channel, n is the logarithm of the airflow sensor, Si is the cross-sectional area measured by the i-th pair of airflow sensors,

[0055] In this preferred embodiment, the airflow sensor is an ultrasonic sensor, and the insertion depth of the probe of the ultrasonic sensor is automatically adjusted in the horizontal direction along the diameter direction of the flue.

[0056] See also Figure 2, at the bottom of the chimney, the fan wind direction inlet Figure 2 As shown by the arrow, the simulation results of the flow field in the flue under given conditions are Figure 1 As shown in the figure, the dark oval is the area with the highest wind speed. Since this area will drift to a certain extent as the temperature in the flue changes, in order to solve the measurement error caused by drift, a two-channel cross ultrasonic arrangement is set up. This arrangement covers the flow rate from the highest to the lowest flow rate. The angle between the two channels will be automatically inspected and adjusted according to the maximum drift of the smooth simulation. Under this arrangement, the flow rates measured by the two channels are v1 and v2 respectively, and the cross-sectional area of the chimney pipe S = πR 2 , then the calculation formula for the flow rate in the flue is: Q = ((v1*k1+v2*k2) / 2)*S. Where k1 and k2 are the weight coefficients corresponding to the flow velocities v1 and v2, and R is the radius of the chimney pipe section.

[0057] See also Figure 3 , at the bottom of the chimney, the fan wind direction inlet Figure 3 As shown by the arrow, the simulation results of the flow field in the flue under given conditions are Figure 2 As shown in the figure, according to the simulation results of the cement chimney, the velocity flow field here is relatively uniform and the gradient is relatively gentle. The four-channel ultrasonic flowmeter to be arranged measures the flow velocities at four different speeds from bottom to top, namely v1, v2, v3, and v4, and corresponds to the areas of four half-moon shapes: S1, S2, S3, and S4. The corresponding flue gas flow formula is: Q = k1*v1*S1+k2*v2*S2+k3*v3*S3+k4*v4*S4, so the flue gas flow formula under n channels is Where ki is the weight coefficient, n is the logarithm of the airflow sensor, 0<n≤12, Si is the cross-sectional area measured by the i-th pair of airflow sensors, where

[0058] In order to measure the concentration in the flue more accurately, three probes were set up at 120 degrees (see Figure 4 As shown) or set up six probes according to the principle of 60 degrees equal division (see Figure 5 The concentration is measured using an arrangement (shown in the figure), in which the insertion depth of each probe can be automatically adjusted horizontally along the flue diameter to ensure accurate concentration measurement. If the concentrations measured by three probes are C1, C2, and C3, the concentration measured by this arrangement is C = (C1 + C2 + C3) / 3. If the concentrations measured by six probes are C1, C2, C3, C4, C5, and C6, the concentration measured by this arrangement is C = (C1 + C2 + C3 + C4 + C5 + C6) / 6.

[0059] The embodiments described above are only used to illustrate the technical ideas and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The scope of the patent of the present invention cannot be limited by these embodiments alone. That is, any equivalent changes or modifications made to the spirit disclosed by the present invention still fall within the scope of the patent of the present invention.

Claims

1. An online measurement system for gas emissions from cylindrical chimneys based on multi-point detection; characterized in that: include: Flow field simulation module that simulates the flow field data in the flue according to given conditions; m airflow sensors for obtaining the gas flow rate in the chimney from different angles; m is a natural number greater than 1; A classification module for classifying and saving the simulation results of the flow field simulation module; the simulation categories include elliptical wind speed model and parallel wind speed model; Based on the classification of the simulation results, the execution module of the detection is executed in the following two ways: Method 1, the area with the highest wind speed is elliptical. The elliptical area will drift to a certain extent as the temperature in the flue changes. When the simulation result is an elliptical wind speed model, two airflow sensors with mutual intersections are activated; Method 1 covers the range from the highest flow rate to the lowest flow rate, and the angle between the two channels will be automatically inspected and adjusted according to the maximum drift of the flow field simulation; Method 2, when the simulation result is a parallel wind speed model, n airflow sensors without mutual intersections are activated; n is a natural number greater than 1; A statistical module that calculates the amount of chimney gas emissions based on the detection results of the execution module.

2. The cylindrical chimney gas emission online metering system based on multi-point detection according to claim 1 is characterized in that: The statistical module includes a first statistical unit that cooperates with the first method and a second statistical unit that cooperates with the second method.

3. The on-line metering system for cylindrical chimney gas emissions based on multi-point detection according to claim 2 is characterized in that: The execution process of the first statistical unit is: Get the flow rates v1 and v2 detected by two airflow sensors; Get the cross-sectional area of the chimney pipe cavity S=πR 2 , where R is the radius of the chimney pipe section; The first calculation formula is: Q=((v1*k1+ v2*k2) / 2)*S; where k1 and k2 are weight coefficients corresponding to flow velocities v1 and v2.

4. The cylindrical chimney gas emission online metering system based on multi-point detection according to claim 2 is characterized in that: The execution process of the second statistical unit is: Obtain the flow rate detected by each airflow sensor; The second calculation formula is: ; Where ki is the weight coefficient of the i-th channel, n is the logarithm of the airflow sensor, Si is the cross-sectional area measured by the i-th pair of airflow sensors, .

5. The cylindrical chimney gas emission online metering system based on multi-point detection according to claim 4 is characterized in that: The airflow sensor is an ultrasonic sensor, and the insertion depth of the probe of the ultrasonic sensor is automatically adjusted in the horizontal direction along the diameter direction of the flue.

6. An online measurement method for cylindrical chimney gas emissions based on multi-point detection, characterized in that: The steps include: S1. A simulation model for obtaining flow field data in the flue according to given conditions; S2. Obtaining a category of the simulation model according to the simulation model; the categories of the simulation include an elliptical wind speed model and a parallel wind speed model; S3. Select an execution mode for the execution module based on the type of simulation model; the execution modes include: Mode 1, where the area with the highest wind speed is elliptical, and the elliptical area will drift to a certain extent as the temperature in the flue changes. When the simulation result is an elliptical wind speed model, two airflow sensors with a mutual intersection are activated; Mode 1 covers the range from the highest flow rate to the lowest flow rate, and the angle between the two channels is automatically inspected and adjusted based on the maximum drift of the flow field simulation; Mode 2, when the simulation result is a parallel wind speed model, n airflow sensors without mutual intersections are activated; n is a natural number greater than 1; S4. Calculate the chimney gas emission according to the detection data obtained by the execution method.

7. The method for online measurement of gas emissions from cylindrical chimneys based on multi-point detection according to claim 6, characterized in that: When the execution mode is mode 1, the chimney gas emission statistics process is as follows: Get the flow rates v1 and v2 detected by two airflow sensors; Get the cross-sectional area of the chimney pipe cavity S=πR 2 , where R is the radius of the chimney pipe section; The calculation formula is: Q=((v1*k1+ v2*k2) / 2)*S; where k1 and k2 are the weight coefficients corresponding to flow velocities v1 and v2.

8. The method for online measurement of gas emissions from cylindrical chimneys based on multi-point detection according to claim 6, characterized in that: When the execution mode is mode 2, the chimney gas emission statistics process is as follows: Obtain the flow rate detected by each airflow sensor; The calculation formula is: ; where k i is the weight coefficient of the i-th channel, n is the logarithm of the airflow sensor, S i is the cross-sectional area measured by the i-th pair of airflow sensors, where .

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