KR20030008899A - The system for measuring the flow rate and the velocity over a chimney by means of multipoints & averaging. - Google Patents

Abstract

PURPOSE: A system for measuring flow rate and flow velocity in a chimney, using multipoint mean is provided to secure reliability in measuring flow rate and flow velocity, using the computational fluid dynamics and various flow velocity-detecting devices. CONSTITUTION: A flow velocity sensor complex(1), detecting flow velocity of fluids flowing in a chimney using pressure difference, temperature difference, or vortex ,and producing an electric current or a voltage signal, is disposed along the direction of the fluids. Each sensor element(16) forming the flow velocity sensor complex(1) senses local flow velocity at a fixed position. The flow velocity sensor complex(1) is semi-fixed and the flow velocity sensor complex(1) detects local flow velocity, with the sensors, while moving to the measurement positions of sensors with a time lag. A tension device unit(6) is mounted to the flow velocity sensor complex(1), to compensate deflection produced at the end of the flow velocity sensor complex(1).

Description

Chimney flow velocity measurement system using multi-point average {The system for measuring the flow rate and the velocity over a chimney by means of multipoints & averaging.}

The present invention effectively improves the measuring method and the measuring device, etc. to calculate the chimney waste gas emissions that cause considerable harm to the human body more reliably and accurately. Until now, there have been considerable difficulties in accurately measuring the waste gas emitted by the chimney.

First, when the temperature is very high (150 ℃ ~ 600 ℃) when applying the general flow rate and flow rate meter, most of the equipment characteristics are mostly deformed.

Second, the measured chimney diameter is very large. Until now, most of the flow rate and flow rate meters have been developed in the form of measuring by applying to pipes of 1m or less, and the flow rate measuring instruments applied to chimneys with diameters of 4m to 15m have been developed. And due to experimental difficulties, no significant progress has been made in development.

Third, the density of gas is so low that it is unreliable when measured by conventional measuring sensor (differential pressure type).

Fourth, a large amount of particulate waste oxide toxic substances in the exhaust gas damages the human body as well as the measuring instrument. In order to minimize this problem, the government plans to add environmental taxes according to these emissions in the next two to three years, and the additional cost is divided according to the measured flow rate, so the accuracy and reliability of this flow measurement are very important variables. . Successful measurement cannot be realized unless the flow meter, which measures flow for precise flow measurement, as well as the flow phenomena of the field conditions to which it is applied, are accurately analyzed and understood. Until now, the flue gas flow rate and flow rate measurement had only formal measurement because there was no regulation and regulation, and reliability could not be guaranteed. Until now, the flow velocity measurement has been used by placing the pitot pipe at one point of the chimney section and considering the flow rate value as the representative flow rate value of the whole chimney section. However, the chief cross section of the chimney is divided as much as possible, and the difference is 40 to 50% when the representative value is calculated by averaging the flow rate values. It is a fact that more than 300 million won is generated annually when the precise flow measurement is done and the one that does not do so is applied to the total amount regulation law in the next two to three years. Therefore, for accurate flow rate measurement, the method of dividing the chimney cross section as much as possible and averaging the flow rate values calculated therein is the most efficient method at present. However, too much effort is required to improve precision, which requires a lot of manpower and expense. Therefore, this problem can be solved by optimally processing the software and approximating the optimal value. In addition, the optimum flow rate value is obtained by reflecting the density and physical quantity of the flow velocity values measured at each sensor position. Once the average value has been computed, it has taken considerable computation and time, and the field experience has not been able to do it because it is difficult to acquire a computer program. The fluid flow of the field exhaust gas accurately reflects parameters such as temperature pressure, viscosity, specific heat, specific heat ratio, Reynolds number, compression coefficient expansion coefficient, vapor pressure, boiling point, freezing point, dew point, saturation point, and triple point component ratio. The lack of interpretable technical skills and the technology of the transmission medium to link theoretical principles to practice were obsolete and did not reach the desired goal.

The operating temperature range is from 110 ℃ to 500 ℃, the pressure is from 0 to 1000mmAq, and the pressure is stable and reliable under the flow conditions including various particles and harmful substances. There are various types of measurement systems to be applied.The criteria for distinguishing between these are the minimum to the maximum flow rate of the fluid flow rate under the conditions to be measured and the temperature to be maintained from the minimum to the maximum. Is the density value high enough to be detected by the measuring sensor, or is the measuring sensor installed in the exhaust gas flow chemical (corrosion, electrolytic) physical (thermal deformation, tissue deformation of the measuring device, noise, static electricity, adhesion)? The present invention has a measurement system that can provide stable and reliable measurement values even under the influence. In addition, the chimney diameter distribution to be installed is about 3.5m to 15m, and at least 4 to 16 points are expected to take the sample values of the velocity average values in these sections. Sampling time varies depending on the conditions, but assuming that approximately 500 sampling values are taken at a maximum of 16 points per second, approximately 8000 sample signals are as stable, reliable, and dynamic as possible (1 second). Hereinafter, the present invention should have a processor system that can be processed. In addition, the measured data should have the function of supplying the measured value to the CPU's Data Logger or FEP (Intermediate Data Collector) for at least 5 minutes. The input that you accept is not the complete data you want. It should be compensated and normalized with data of real values that match the measurement site conditions. The values reflected here include flow coefficients, compression coefficients, expansion coefficients, specific heat ratios, viscosity coefficients, maximum flow rate equations (Newton-Gregory equations), Lagrange polynomials or spline equations, gasviscosities simplified equations, heat capacity simplified equations, Gaussian, Thebycheff The results are reflected using the Centeroid, Graphical intergration equations, numerical integration equations, arithmetic mean weight equations, Bernoulli flow equations, thermal tropic analysis algorithms, vortex versus frequency velocity equations, ultrasonic doppler effects, and transit effects. Measurement reflecting performance within ± 2%, reproducibility within 1% and linear error within 2% when the accuracy of the final output value (expressed as the highest deviation value from the reference value within the range that can be measured by the instrument) reflecting these variables and parameters Build the system

1 is a partial view of the flow rate flow rate detection of the present invention

2 is a block diagram of a flow rate flow rate signal processing transmission support portion combined with FIG.

3 is an installation diagram illustrating an installation example of FIG. 1.

4 is a block diagram of an ADC according to the present invention.

Fig. 5 shows Anaro signal processing components related to the present invention.

6 is an LCD interface component related to the present invention

7 is a RS 232C communication port connection diagram related to the present invention.

8 is an arrangement (d: diameter) of the flow rate sensor from 8 to the chimney diameter of 3.75 to 4.25m

9 is a flow rate sensor arrangement (d: diameter) from the chimney diameter of 4.26m to 4.75m

10 is a flow rate sensor arrangement (d: diameter) from the chimney diameter to more than 4.76m to 5.25m

11 is a flow rate sensor arrangement (d: diameter) from the chimney diameter of 5.26m to 5.75m

12 is a flow rate sensor arrangement (d: diameter) from the chimney diameter of 5.76m to 6.25m

13 is a flow rate sensor arrangement (d: diameter) from the chimney diameter of 6.26m to 6.75m

14 is a flow rate sensor arrangement (d: diameter) from a chimney diameter of 6.76 m to 7.25 m.

15 is a flow rate sensor arrangement (d: diameter) from the chimney diameter of 7.26m to 7.75m.

16 is a flow rate sensor arrangement (d: diameter) from a chimney diameter of 7.76 m to 8.25 m.

17 is a flow rate sensor array (d: diameter) from the chimney diameter of 8.26m to 8.50m

18 is a flow rate flow signal processing flowchart

We combine hardware and software to achieve the goals listed above. The hardware detects the flow velocity at each location point by placing a flow rate sensor that detects the flow velocity in the optimal position by thebycheff splitting method according to the diameter of the chimney from Figure 1 to Figure 10.

(1) The type of excitation flow rate sensor can be heated, vortex differential pressure, or ultrasonic depending on flow rate measurement conditions (temperature, pressure, flow rate range, and particles present in the flow).

(A) Heat wire measures the flow rate by using the convective heat transfer effect between the reference resistance temperature sensor and the comparative temperature, and the output value is the mass flow rate value reflecting the change in density. This mass flow rate value is output to standard signal 4-20mA and converted to 1 ~ 5V output for digital signal processing on the computer, and the desired value is generated by various calculation programs.

(B) Vortex flow rate sensor measures the flow rate by using the number of vortices generated by the vortex generator in proportion to the flow rate. However, since the bluff body alone cannot measure a wide range of flow velocity when measuring the chimney flow rate, an ultrasonic bandwidth is formed here, and the carrier frequency and the signal frequency are modulated each time the vortex passes through this region. The flow signal generated here is an analog signal or digital signal of 1 to 5V or 4 to 20mA and the signal from each sensor consisting of multi-points is used to calculate the flow velocity average using the above-mentioned average algorithm.

(C) Differential pressure flow rate sensor, which measures the flow rate using the reduced pressure difference while converting the total pressure formed at the front of the sensor into speed pressure (dynamic pressure), and in order to convert the flow rate signal into an electrical standard signal, a conversion transmitter must be used in parallel. Should be used. The electrical signal of each sensor generated here is converted to the flow rate value, and the average flow rate value is calculated using the aforementioned average algorithm.

(D) Ultrasonic sensors can be used to detect the flow rate of flue gas, and this signal is received by the receiver when ultrasonic waves are sent from the ultrasonic transmitter. The received ultrasonic sensor immediately transmits and transmits a recently received signal. In addition, the sensor that used to transmit previously is switched to the receiving function and receives a signal. If the fluid moves along the path of this sound wave, a phase difference occurs between the transmitted and received signals.

The flow velocity is measured using this phase difference. This also averages the signals received from the various sensors to calculate the average flow rate.

(2) In step (1), the electric velocity signal generated by the velocity measuring device is linked with the inherent velocity range of the instrument to generate the actual velocity value. In general, high-frequency components are removed using a low pass filter from 1 to 5V high-speed electric analog signals (refer to the circuit diagram) and only quantized typical flow rate signal components to 255 levels. In this way, the flow rate signals from each sensor are processed simultaneously. There are three types of signals.

(A) It is a signal from the flow rate sensor. This signal comes in two forms: the volumetric flow and the mass output. The flow rate signal output in volume form is multiplied by the density value and converted to the mass flow rate value.

(B) The pressure signal value from the pressure sensor. In order to calculate the density value of the exhaust gas flowing in the chimney, the pressure has a big influence on the density value under the gas flow condition and compensates the flow rate value by converting the absolute pressure value output from the pressure sensor measuring this pressure into a standard electric signal. Is used to calculate the density value.

(C) The temperature signal value from the temperature sensor. In order to calculate the density value of the exhaust gas flowing in the chimney, the temperature has a big influence on the density value under the gas flow condition, and the absolute temperature value output from the temperature sensor measuring this temperature is converted into a standard electric signal to compensate for the flow rate value. It is used for density value calculation

(D) To calculate the density value of the mixed gas, calculate the average molecular weight of the mixed gas using Dalton's partial pressure law, calculate the gas constant, and substitute the calculated values in the ideal state equation to calculate the density value.

(E) Flow rate sensor In case of hot wire type, the flow rate value measured under the measurement condition is converted to flow rate at 20 ℃ and 1 atmosphere.

(F) If the flow rate sensor is a vortex type, ultrasonic type or differential pressure type, calculate the density value under the measurement conditions and calculate the mass flow rate and convert it to the flow rate value at 20 ℃ and 1 atmosphere.

(G) The calculation of the velocity signal reflecting the density is done in computer programming on the microprocessor 847/877 chip.

(H) It has a built-in compensation algorithm for each input value.

(I) The output value from the microprocessor is indicated to the LCD and this indication can be adjusted manually.

(D) averaging multiple flow rate values input from each sensor, standard flow rate values, compression coefficients, expansion coefficient flow rate conversion values, integration values, etc.Entropy index, viscosity value, Reynolds number value Since the graph representation can be implemented in a microprocessor, it takes a lot of time and money. Therefore, the signal is transmitted to a personal computer (P / C) using an A / D converter and multiplex.

(3) Various calculation formulas and calculation programs are built into the P / C to compensate for irrationality and nonlinearity in flow rate measurement conditions. Introduced the design of the operating system to process the input data values stably and systematically, so that the processed data can be saved, archived document output, data transmission and communication.

(A) The averaging mathematical algorithm was programmed as follows.

a) when the chimney cross section is circular

Vo here is the center velocity of the chimney Flow rate detected at the sensor's location Is the distance from the chimney center where the chimney radius sensor is located.

The central flow velocity Vo from above is found by The flow velocity value measured at each position point If this is used, it forms the point where the sensor is located and one coordinate point to make the curve equation.

m: constant given by pipeline friction is typically given (m = 6.4)

And the equation of the curve

Where the maximum flow rate occurs and its value

= gradient silver Derivative of

b) the chimney cross section is square

here

H: Overall height of the rectangular cross section h: Partial height of the rectangular cross section

Where V1, V2 .... Vn are flow velocity values measured at each split point when the chimney section is divided by n

Is the value expressed as the ratio from the reference point to the angle measurement when the total length of one rectangular cross section is taken.

m: A constant given by pipeline friction is typically given (m = 6.4).

(B) The algorithm of the following formula is embedded to automatically calculate the viscosity of the measuring fluid.

here

Cp: viscosity value expressed in Centipoise

k, c: constant given to the representative flue gas components given below

CO2-K (0.298) c (0.854), CO-K (0.194) c (0.674), H2 K (0.089) c (0.652) O2 K (0.219) c (0.674), H2O K (0.422) c (1.067) , N2 k (0.224) c (0.720) Air K (0.194) c (0.674)

: Component ratio of element in the fluid to be measured

: Molecular weight of component

: Viscosity value of each component

(C) The following algorithm is built in program to automatically perform density compensation on the measured average flow velocity.

here : Mass flow rate value detected by the measuring sensor

(D) An algorithm for calculating the isentropic index of the measurement fluid is built-in.

In the above formula, the A and y values are given in the chart below.

: Component ratio of element in the fluid to be measured

: Molecular weight of each component

(E) Density calculation

Enter the pressure sensor, temperature sensor, and component ratio to automatically calculate the density value from the equation below.

here

: Density value (kg / m3)

R: gas constant value

: Component ratio of element in the fluid to be measured

: Molecular weight of component

(4) signal processing module

(A) Analog Sensor Interface

The 16F874 integrates eight 10-bit ADCs. The analog input is charged to the Sample and Hold (S & H) capacitor, and the voltage charged to the S & H Capacitor is input to the ADC. The ADC converts Analog to Digital using the Successive Approximation method. Here the analog value is converted to a digital value of 10 bits.

The ADC operates only in sleep mode. In sleep mode, the ADC uses its own RC oscillator to derive the conversion clock. The ADC module consists of four registers as follows.

-. A / D Result High Register (ADRESH)

-. A / D Result Low Register (ADRESL)

-. A / D Control Register0 (ADCON0)

-. A / D Control Register1 (ADCON1)

(B) Analog signal processing

The PIC16F874 integrates eight 10-bit ADCs, making it a very useful device for converting analog signals to digital. Here, it is designed to process 10 analog signals using 2 analog multiplexers. The circuit designed here is as follows.

(C) LCD Interface

The controller needs to send and receive data in order to control the LCD. There are two ways to send and receive data: serial data and parallel data. In this case, we chose the serial transmission method.

An explanation diagram thereof is as follows.

(D) Usart interface

The function of RS232 serial communication is composed as follows. In order to transmit a lot of data, a parallel method is used, but since this measurement system does not require much data, a serial communication method is used.

TXD-Transmit Data

Signal line from which serial communication data comes out when an asynchronous serial communication device sends information to an external device.

RXD-Receive Data

Signal line for receiving serial communication data from an external device.

.

Claims (5)

A system that measures the optimal average flow velocity of a chimney by combining a number of flow rate measurement sensors. It includes the following assembly units: (A) Individual flow rate and flow rate sensors (heated, vortex, differential pressure, ultrasonic) installed at right angles to the flow direction of the flow rate to be measured to generate a flow rate flow signal by detecting the dynamic change in the physical energy of the fluid. Flow rate and flow rate sensing part This includes a turbine transducer (converter) that generates an electrical signal (4-20mA, 1-5V or a vortex frequency proportional to the flow rate) of the physical variation and frequency detected by each sensor. (B) an analog digital converter which converts the analog electrical signal detected in step (a) into a digital signal. Here, a conversion algorithm (sample rate, switching logic) related to the present invention is embedded with a microprocessor chip using an assembler language. (C) The signal processed in step (b) is transmitted to an external computer using a MAX 232 serial communication chip. Here, the communication protocol related to the present invention is programmed into the Max 232 chip. (D) The signals sent in step (c) are input and the physical and chemical variables used in various calculations, numerical analysis, graphing and flow compensation are retained or retained as default values. The average value is calculated using the flow rate and flow rate signals input from each sensor. (E) The data calculated in step d) is transmitted to an external host computer at predetermined time units. (F) The LCD display will display the compensation and converted flow rates, flow rates and integration values generated in step (d) together with the pressure and temperature values of the current process. Apparatus and system for measuring the flow rate and flow rate of claim 1 Here, the apparatus for calculating the average flow rate by receiving the flow rate signal generated by each measurement sensor calculates the average value using the following formula. A) the chimney cross section is circular; Vo here is the center velocity of the chimney Flow rate detected at the sensor's location Is the distance from the chimney center where the chimney radius sensor is located. The central flow velocity Vo from above is found by The flow velocity value measured at each position point If this is used, it forms the point where the sensor is located and one coordinate point to make the curve equation. m: constant given by pipeline friction is typically given (m = 6.4) And the equation of the curve Where the maximum flow rate occurs and its value = gradient silver Derivative of B) If the chimney cross section is square here H: Overall height of the rectangular cross section h: Partial height of the rectangular cross section Where V1, V2 .... Vn are flow velocity values measured at each split point when the chimney section is divided by n Is the value expressed as the ratio from the reference point to the angle measurement when the total length in one direction is taken m: A constant given by pipeline friction is typically given (m = 6.4). The flow rate and flow rate measurement system of claim 1, wherein the flow rate and flow rate compensation device is performed using the following equation (A) Calculation of viscosity coefficient value Cp: viscosity value expressed in Centipoise k, c: constant given to the representative flue gas components given below CO2-K (0.298) c (0.854), CO-K (0.194) c (0.674), H2 K (0.089) c (0.652) O2 K (0.219) c (0.674), H2O K (0.422) c (1.067) , N2 k (0.224) c (0.720) Air K (0.194) c (0.674) : Component ratio of element in the fluid to be measured : Molecular weight of component : Viscosity value of each component (B) density compensation here : Mass flow rate value detected by the measuring sensor (C) isentropic index In the above formula, the A and y values are given in the chart below. : Component ratio of element in the fluid to be measured : Molecular weight of each component (D) Density value calculation here : Density value (kg / m3) R: gas constant value : Component ratio of element in the fluid to be measured : Molecular weight of component The flow rate and flow measurement device and system of claim 1 is an averaged device, which calculates the average value by calculating the average maximum flow rate and compensating the local flow rate at the point where the angular flow sensor is located. The flow rate and flow rate measurement system of claim 1 is the equation of the flow curve of the excitation flow curve. Choose one of the methods to produce the equation.