KR100872151B1 - Auto smapler having an accurate isokinetic sampling control function through automated differential pressure compensation and method for controlling isokinetic sampling using the same - Google Patents

Abstract

An auto-sampler having an accurate isokinetic sampling control function through automated differential pressure compensation and a method for controlling isokinetic sampling using the auto sampler are provided to auto-control a flow control valve such that an absorption flux indication value corresponds to a calculated isokinetic sampling flow rate and correct an error generated when a difference between the total pressure and static pressure of exhaust gas to precisely measure the flux of the exhaust gas to thereby achieve exact isokinetic sampling. An auto-sampler is connected to a probe including a pitot(2), a suction nozzle and a temperature sensor(3) through an umbilical cable(50). The auto-sampler includes a temperature signal line(110) delivering a sensed chimney temperature signal, a sample transfer tube(120) in which an inhaled exhaust gas sample is transferred, a vacuum pump(125) providing an absorption force for transferring the sample, a gas meter(128) measuring the temperature of the sample, motor-operated valve(122) controlling the flow rate of the exhaust gas sample, a hydrostatic port(130) and a voltage port(140) to which the static pressure and voltage of the inhaled exhaust gas are respectively delivered, a static pressure sensor(135) measuring the hydrostatic of the exhaust gas, a differential pressure sensor(150) connected to the hydrostatic port and the voltage port to measure a dynamic pressure corresponding to a difference between the static pressure and voltage of the exhaust gas, a differential pressure correction(160) which selectively supplies the air and exhaust gas at fixed periods, and a controller(180) controlling the motor-operated valve.

Description

AUTO SAMPLER HAVING AN ACCURATE ISOKINETIC SAMPLING CONTROL FUNCTION THROUGH AUTOMATED DIFFERENTIAL PRESSURE COMPENSATION AND METHOD FOR CONTROLLING ISOKINETIC SAMPLING USING THE SAME}

The present invention relates to an autosampler for calculating the amount and concentration of dust and pollutants in the exhaust gas by automatically collecting particulate matter (dust) and gaseous substances discharged from the chimney, and a method for controlling constant velocity using the same. The present invention relates to an autosampler and a constant velocity suction control method using the same to enable precise control of constant velocity suction by correcting a differential pressure sensor 150 used in measuring the exhaust gas flow rate of a chimney in real time to minimize the error of the velocity data.

In general, chimneys are installed in factories or other industrial facilities to discharge various waste gases and dusts generated during the production and processing of products. During the off gas discharged through the chimney such that it contains harmful gases, such as particulate matter, such as dust and NO _X, SO _X. If these dusts or harmful gases are released to the atmosphere, they can cause diseases such as respiratory diseases in humans, and they can be the cause of acid rain and other environmental pollution by polluting the soil as well as the air. .

Accordingly, the government has established regulations on the allowable discharge of particulate matter and gaseous substances from chimneys installed at each factory or other industrial facilities, and the amount and concentration of pollutants emitted from each chimney in real time. In order to do so, it is mandatory to establish a facility to collect and analyze emission gas samples at each of the chimneys of each workplace and to report the results of the analysis periodically.

1 schematically shows a conventional sampling facility installed for the collection and analysis of such exhaust gases as an example.

As shown in the related art, in order to collect and analyze the exhaust gas sample, a suction nozzle 1 bent downward through the chimney S wall is inserted to suck a portion of the exhaust gas discharged upwardly from the chimney. Dust in the exhaust gas sucked is collected by the silica fiber filter paper provided in the filter paper holder 4 which is heated and maintained at a predetermined temperature. The filter paper in which dust is collected is sufficiently dried at a temperature of 110 to 115 ° C. over 1-3 hours to remove adherent moisture, and the weight concentration of the dust in the exhaust gas is calculated by measuring the weight of the dried dust.

Then, the exhaust gas from which the dust is removed passes through the impinger train 5, as shown in FIG. The impinger train (5) is a box body in which a plurality of, usually four impinger (7) is installed in the cooling tank (6), while the exhaust gas is removed through the four impinger (7) sequentially Water is absorbed and removed by the absorbent liquid in the impinger 7 and cooled by the cooling tank 6 before being transferred through the connecting pipe 8. The connecting pipe 8 is provided with a vacuum pump 11 which sucks the exhaust gas from the chimney and provides the driving force necessary to transfer the exhaust gas through the connecting pipe 8. The exhaust gas sample sucked in accordance with the operation of the vacuum pump 11 is supplied to the gas meter 12, the data such as the flow rate and pressure of the exhaust gas sample, inlet and outlet temperature is measured in the gas meter 12 Thus, the concentration of pollutants in the exhaust gas can be measured.

On the other hand, in the case of collecting and analyzing the exhaust gas sample by this method, the constant velocity suction of the exhaust gas sample should be realized in order to reduce the measurement error of the dust concentration in the exhaust gas. By constant velocity suction, it means that the exhaust gas sample is sucked at the same speed as the flow rate of the actual exhaust gas in the chimney. Dust is a particulate matter that moves at the speed of the exhaust gas and has inertia. For this reason, when suctioning at a speed lower than the exhaust gas speed, the heavy dust particles are sucked by the inertia, and only the small weight particles are different. As it exits, the dust concentration readings will be higher than the actual dust concentration. Therefore, it is only when the constant velocity suction is realized that the concentration of dust measured from the sample of aspirated exhaust gas becomes equal to the concentration of dust contained in the actual exhaust gas.

In order to realize such constant velocity suction, in the conventional sampling system, as shown in Fig. 1, the pitot tube 2 and the temperature sensor 3 are further inserted into the chimney, and the outlet side of the gas meter 12 is inserted. The orifice 13 was installed. The pitot tube 2 and the orifice 13 were provided with a phytomanometer 9 and an orifice manometer 14 for measuring differential pressure, respectively. Through the phytonometer 9 connected to the pitot tube 2, the differential pressure, that is, the dynamic pressure h, of the voltage Pt (total pressure) of the exhaust gas and the static pressure (Ps) is measured, and the orifice manometer 14 is measured. Through), the pressure drop of the exhaust gas sample passed through the orifice 13 is measured. Dynamic pressure measurement using the pitot tube (2) and the diameter, pitot coefficient, orifice coefficient, temperature, and pressure of the suction nozzle (1) were calculated by a formula, and the corresponding pressure drop (h) at both ends of the orifice was calculated. Constant velocity suction is realized by operating the flow control valve 10 so that the pressure drop across the actual orifice measured by the same value is equal to the calculated value.

However, the exhaust gas sampling and analysis method using the conventional sampling equipment as described above applies the correlation formula between the dynamic pressure value of the pitot pipe 2 and the orifice pressure drop value without knowing the flow rate and the suction flow rate of the exhaust gas. As a simple method, if the orifice is contaminated with oil, dust, etc., it may cause a large error, so that it is not only inconvenient to clean periodically, but also has a disadvantage of separately collecting and calculating various data. In addition, there was a limit to precise flow rate control because the flow rate control valve 10 had to be manually adjusted, and precise constant velocity suction was not achieved due to an error in measuring the total pressure of the exhaust gas and the differential pressure of the static pressure.

Therefore, the present invention was devised to solve the problems of the conventional exhaust gas sample collection and analysis equipment and method as described above, and measures the flow velocity of the exhaust gas discharged through the actual chimney, and realizes constant velocity suction based on this. The flow rate control valve is automatically adjusted to calculate the constant velocity suction flow rate required to achieve the same, and the suction flow rate indication value is consistent with the calculated constant velocity suction flow rate. An object of the present invention is to provide an autosampler capable of precisely measuring the flow velocity of exhaust gas to realize accurate constant velocity suction.

The objects and advantages of the present invention will be described in more detail below, and will be further embodied by the examples. Furthermore, the objects and advantages of the present invention can be realized by the means indicated in the claims and combinations thereof.

Autosampler 100 according to the present invention for achieving the above object, the chimney is connected to the probe including a pitot tube 2, the suction nozzle, and the temperature sensor 3 by a umbilical cable 50 An auto sampler for automatically collecting and analyzing exhaust gas, comprising: a temperature signal line (110) for transmitting a chimney temperature (Ts) signal detected from the temperature sensor (3); A sample transfer pipe 120 through which the discharge gas sample sucked from the suction nozzle is transferred; A vacuum pump 125 installed at the sample transfer pipe 120 to provide a suction force for transferring a discharge gas sample; The suction flow rate (rFlow) of the exhaust gas sample, the gas meter pressure (Pm), and the temperature (Tm) of the exhaust gas sample flowing into the gas meter 128 are provided at the rear end of the vacuum pump 125 of the sample transfer pipe 120. A gas meter 128 for measuring; An electric valve 122 which opens and closes according to the operation of the motor and adjusts the flow rate of the exhaust gas sample conveyed through the sample conveying pipe 120; A positive pressure port 130 and a voltage port 140 which receive the positive pressure and the voltage of the exhaust gas sucked from the pitot tube 2, respectively; A constant pressure sensor 135 connected to the constant pressure port 130 to measure a static pressure of the exhaust gas; A differential pressure sensor (150) connected to the constant pressure port (130) and the voltage port (140) for measuring a dynamic pressure (h) that is a differential pressure between the positive pressure of the exhaust gas and the voltage; A differential pressure compensation unit 160 for selectively supplying air and exhaust gas to the differential pressure sensor 150 at regular intervals to correct the zero point of the differential pressure sensor 150; The differential pressure compensation unit 160 is controlled to selectively supply the discharge gas and the air to the differential pressure sensor 150, correct the exhaust gas differential pressure measurement value based on the air differential pressure measurement value, and adjust the temperature sensor 3 and the gas. Receives the measured signals from the meter 128 and the static pressure sensor 135 and the differential pressure sensor 150, calculates the exhaust gas density and flow rate, calculates the constant velocity flow rate for realizing constant velocity suction based on the calculated flow rate And a controller 180 for controlling the electric valve 122 so that the gas meter suction flow rate is equal to the constant velocity flow rate by comparing the calculated constant flow rate and the suction flow rate measured by the gas meter 128.

Here, the differential pressure preservation unit 160 includes: a voltage transfer path 161 connected between the voltage port 140 and the differential pressure sensor 150 to transfer the voltage of the discharge gas to the differential pressure sensor 150; A positive pressure transmission channel 162 connected between the positive pressure port 130 and the differential pressure sensor 150 to transfer the positive pressure of the exhaust gas to the differential pressure sensor 150; A first common passage 163 and a second common passage 164 connected between the voltage transfer passage 161 and the static pressure transfer passage 162, respectively; An air supply passage 166 connected to the common passages, through which air supplied from the outside is transferred; An air solenoid valve (S5) provided in the air supply passage (166) to control supply and blocking of air; And a three-way solenoid valve (S1, S2, S3, S4) respectively installed at the connection portion between the voltage transfer passage 161 and each common passage, and the connection portion between the constant pressure transfer passage 162 and each common passage.

The controller 180 opens the air solenoid valve to supply air and simultaneously controls the opening and closing direction of the three-way solenoid valves S1, S2, S3, and S4 to introduce air into the differential pressure sensor 150. Receives the measured air differential pressure measurement value, closes the air solenoid valve to cut off the supply of air, and simultaneously controls the opening and closing direction of each of the three-way solenoid valves S1, S2, S3, and S4 to control the voltage transfer path 161. And the exhaust gas is introduced into the differential pressure sensor 150 through the constant pressure transmission flow path 162 and the measured exhaust gas differential pressure measurement value is received, and the exhaust gas pressure difference is reduced by the air differential pressure measurement value. Correct the gas differential pressure.

On the other hand, the sample transfer pipe 120 is provided at the rear end of the electric valve 122 and the first adjustment valve 123 for manually adjusting the flow rate of dust collected in the exhaust gas sample; An orifice tube 124 connected to the electric valve 122 and the first adjustment valve 123 in parallel to transfer the gas sample in the exhaust gas; In addition, the second adjustment valve 127 for finely adjusting the flow rate is provided in the bypass pipe 126 connected in parallel to the vacuum pump 125 and used for the purpose of preventing the overload of the vacuum pump 125 when the low flow rate is collected. It includes more.

In addition, the constant velocity suction control method according to the present invention is a constant velocity of the flue gas using an autosampler connected to the probe including the pitot tube (2), the suction nozzle, and the temperature sensor (3) by an umbilical cable (50). A suction control method, comprising: measuring a chimney temperature (Ts) with the temperature sensor (3); Sucking the exhaust gas sample from the suction nozzle using a suction force of the vacuum pump 125 and transferring the sample through the sample transfer pipe 120; Measuring a suction flow rate (rFlow), a gas meter pressure (Pm), and a temperature (Tm) of the exhaust gas sample flowing into the gas meter (128) of the exhaust gas sample transferred through the sample transport pipe (120); Supplying air to the differential pressure sensor 150 and measuring the differential pressure; Measuring the differential pressure between the static pressure and the voltage of the exhaust gas sucked from the pitot pipe (2) by the differential pressure sensor (150); Correcting the exhaust gas differential pressure by subtracting the differential pressure between the positive pressure and the voltage of the exhaust gas measured by the differential pressure sensor 150 by the differential pressure measurement value of the air; Measuring the static pressure of the exhaust gas sucked from the pitot tube (2); Receiving the measured signals from the temperature sensor (3) and the gas meter (128), and the static pressure sensor (135) and the differential pressure sensor (150), and calculating exhaust gas density and flow rate according to a predetermined calculation formula; Calculating a constant velocity flow rate for realizing constant velocity suction based on the calculated exhaust gas flow rate, and comparing the calculated constant velocity flow rate with the suction flow rate measured from the gas meter 128; And adjusting the opening and closing degree of the electric valve 122 installed in the sample transfer pipe 120 so that the gas meter suction flow rate is equal to the constant velocity flow rate.

According to the present invention as described above, it is possible to minimize the suction flow rate error by accurately measuring the flow rate of the exhaust gas discharged through the actual chimney through the differential pressure correction, and calculate the constant velocity suction flow rate for realizing the constant velocity suction Therefore, since the electric valve is automatically adjusted according to the calculated constant velocity suction flow rate, it has an excellent effect that can realize precise and accurate constant velocity suction.

Hereinafter, the configuration and operation relationship of the autosampler 100 according to the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

2 is a configuration diagram of the entire sampling system including the autosampler according to the present invention, Figure 3 is a detailed configuration diagram of the differential pressure sensor 150 and the differential pressure compensation unit 160 of the autosampler according to the present invention.

As shown in FIG. 2, the sampling system including the autosampler 100 according to the present invention, like the conventional system, has a pitot tube 2, a suction nozzle 1, and a temperature sensor 3 through a chimney wall. Are inserted, and these are connected to the autosampler 100 according to the invention by an umbilical cable 50. The umbilical cable 50 includes a vacuum hose for exhaust gas suction connected to the suction nozzle 1, a soft PVC hose for connecting a pitot pipe, a temperature compensation conductor, and a power supply line. Through the umbilical cable 50, the exhaust gas sample, the voltage (Pt) and the static pressure (Ps) of the exhaust gas, chimney temperature (Ts), probe temperature (Tb), heater temperature (Th), impinger temperature (Ti) is passed to the autosampler.

The autosampler according to the present invention sucks the exhaust gas sample delivered through the umbilical cable 50 at a constant velocity in the sampling system as described above, and contaminates the exhaust gas sample based on various pressure and temperature information. It is a device to measure the amount of substances and the degree of contamination. As shown in FIG. 2, the autosampler includes a temperature signal line 110, a sample transfer pipe 120, a vacuum pump 125, a gas meter 128, an electric valve 122, a voltage port 140, and a constant pressure port. 130, the positive pressure sensor 135, the atmospheric pressure sensor 170, the differential pressure sensor 150, the differential pressure compensator 160, the air supply port 165, the display unit, and a control unit for controlling the overall operation of the autosampler ( 180).

The temperature signal line 110 automatically controls various temperature signals transmitted through the umbilical cable 50, that is, the chimney temperature Ts, the probe temperature Tb, the heater temperature Th, and the impinger temperature Ti. Pass it to the sampler.

The sample transfer pipe 120 is a main pipe through which the discharge gas sample from which moisture is removed by passing through the impinger train 5 is transferred for measurement, and a distal end of the sample transfer pipe 120 is exposed to the outside to be described later. 128), the sample having been measured can be discharged to the outside of the autosampler.

The sample transfer pipe 120 is provided with a vacuum pump 125 that provides a suction force for transferring the exhaust gas sample, as in the conventional system, the gas for analyzing the exhaust gas sample sucked in the rear end of the vacuum pump 125 Meter 128 is provided. The gas meter 128 is a dry gas meter mentioned above, and the exhaust gas suction flow rate rFlow, the gas meter pressure Pm, and the temperature Tm of the exhaust gas sample flowing into the gas meter 128 are measured. The measured values are transmitted to the controller 180 to be described later. In addition, an oxygen sensor 129 is further provided at the rear end of the gas meter 128 to measure the concentration of oxygen in the exhaust gas sample and transmit the measured value to the controller 180.

On the other hand, the autosampler according to the present invention is further provided with an electric valve 122 for realizing constant velocity suction. The electric valve 122 is installed at the front end (primary side) of the sample transfer pipe 120, more specifically, the vacuum pump 125. The electric valve 122 is a valve operated according to the driving of the motor, the opening and closing is controlled by the controller 180 to be described later, by adjusting the amount of the exhaust gas sample drawn through the sample transfer pipe 120 in real time Aspiration is achieved.

On the other hand, the autosampler according to the present invention additionally includes a first adjustment valve 123 and the orifice tube 124, the bypass pipe 126 and the second adjustment valve 127.

As shown in FIG. 2, the first adjustment valve 123 is a manual valve provided at the rear end (secondary side) of the electric valve 122, and is a valve for adjusting the flow rate of dust in the exhaust gas sample. It is called Coarse Adjust Valve.

The orifice tube 124 is a tube in which the gas sample in the exhaust gas sample is transferred, and is connected in parallel to the electric valve 122 and the first adjustment valve 123. In addition, the second adjustment valve 127 is a fine adjust valve provided in the bypass pipe 126 connected in parallel to the vacuum pump 125 for the purpose of preventing overload of the pump during low flow rate sampling. Used.

On the other hand, the autosampler according to the present invention is provided with a positive pressure port 130 and a voltage port 140. The positive pressure port 130 and the voltage port 140 are respectively connected to the positive pressure pipe and the voltage pipe of the pitot tube 2 through the umbilical cable 50 to measure the flow rate through the measurement of the differential pressure between the positive pressure and the voltage of the exhaust gas. Connected. The positive pressure port 130 and the voltage port 140 are connected to the differential pressure sensor 150, which will be described later, respectively, and the positive pressure port 130 is provided with a positive pressure sensor 135 independently to suction for realizing the flow rate and constant velocity suction later. The static pressure of the exhaust gas required for the amount calculation is measured and transmitted to the controller 180.

The differential pressure sensor 150 measures the differential pressure between the positive pressure of the exhaust gas and the voltage, that is, the dynamic pressure (h), and outputs the electric signal of 4 to 20 mA to the controller 180 to transmit the differential pressure to the wire (DWYER). It is preferred that a sensor be used.

As described above, the differential pressure sensor 150 measures the differential pressure between the positive pressure and the voltage to measure the flow rate of the exhaust gas discharged through the chimney so that the autosampler according to the present invention can realize the constant velocity suction. This accurate measurement allows precise constant velocity suction, so the error should be minimized when measuring the differential pressure between the positive pressure and the voltage. Thus, in order to reduce the differential pressure error between the positive pressure and the voltage measured by the differential pressure sensor 150, the autosampler according to the present invention performs the automatic zero correction function of the differential pressure sensor 150, the differential pressure compensation to perform such automatic zero correction function The government 160 is provided. 3 shows a detailed configuration of such a differential pressure correction unit 160.

As shown in FIG. 3, the differential pressure compensator 160 includes a voltage transfer passage 161, a positive pressure transfer passage 162, a first common passage 163, a second common passage 164, and an air supply passage ( 166), the first three-way solenoid valve (S1), the second three-way solenoid valve (S2), the third three-way solenoid valve (S3), the fourth three-way solenoid valve (S4) and the air solenoid valve (S5).

The voltage transfer path 161 is a flow path for transferring the voltage of the exhaust gas to the differential pressure sensor 150 and is connected between the voltage port 140 and the differential pressure sensor 150 of the autosampler according to the present invention. That is, the exhaust gas collected through the voltage pipe of the pitot pipe 2 installed in the probe of the chimney is introduced into the voltage port 140 of the autosampler according to the present invention through the umbilical cable 50, and the introduced exhaust gas Is transferred to the differential pressure sensor 150 through the voltage transfer passage 161.

The positive pressure transmission channel 162 is a channel for delivering the static pressure of the exhaust gas to the differential pressure sensor 150, and is connected between the positive pressure port 130 and the differential pressure sensor 150 of the autosampler according to the present invention. Accordingly, the exhaust gas collected through the positive pressure pipe of the pitot pipe 2 installed on the probe of the chimney is introduced into the positive pressure port 130 of the autosampler according to the present invention through the umbilical cable 50, and the introduced discharge is discharged. The gas is transferred to the differential pressure sensor 150 through the positive pressure transmission channel 162.

A first common channel 163 and a second common channel 164 are connected between the voltage transmission channel 161 and the static pressure transmission channel 162, and a connection portion between the voltage transmission channel 161 and each common channel, and Three-way solenoid valves (S1, S2, S3, S4) are respectively installed at the connection portion between the constant pressure transmission passage 162 and each common passage, and each common passage is introduced from the air supply port 165. Air supply passages 166 for supplying air are respectively connected. In addition, the air supply passage 166 is provided with an air solenoid valve S5 for controlling supply and interruption of air. Here, the three-way valve installed in the voltage transfer passage 161 is named as the first three-way solenoid valve (S1) and the third three-way solenoid valve (S3) in the order close to the voltage port 140, the positive pressure transfer passage (162) The three-way solenoid valves installed in the second three-way solenoid valve (S2) and the fourth three-way solenoid valve (S4) in the order close to the constant pressure port 130 will be named.

In addition, in FIG. 3, three directions of each of the three-way solenoid valves S1, S2, S3, and S4 are denoted by Arabic numerals, and hereinafter, the direction indicated by '1' is indicated by the first direction and '2'. The second direction, the direction indicated by '3' is named as the third direction. In addition, always open direction side of each three-way solenoid valves (S1, S2, S3, S4) is 'COM', while it is open during differential pressure measurement, and closed direction side for zero calibration is 'NO', and closed for differential pressure measurement. In the zero calibration, the direction of the open direction is marked with 'NC', and the closed direction is separated by hatching.

Hereinafter, the differential pressure measurement and correction method will be described with reference to FIGS. 3 and 4. First, referring to FIG. 3, as the exhaust gas flows in from the voltage port 140 and the constant pressure port 130, the differential pressure measurement is started. At this time, the first side of the first three-way solenoid valve (S1) is always open, the second side is closed during the differential pressure measurement, the third side is open during the differential pressure measurement, the exhaust gas flowing from the voltage port 140 is the voltage Passes through the first three-way solenoid valve (S1) on the transmission passage (161). Then, the first one side of the third three-way solenoid valve (S3) is opened during the differential pressure measurement, the second side is closed during the differential pressure measurement, and the third side is always open, so passes through the first three-way solenoid valve (S1) One exhaust gas is also passed through the third three-way solenoid valve (S3) to the differential pressure sensor 150. Similarly, the exhaust gas introduced through the constant pressure port 130 passes through the second three-way solenoid valve S2 and the fourth three-way solenoid valve S4 in order and is transmitted to the differential pressure sensor 150. That is, the exhaust gas introduced from the voltage port 140 and the positive pressure port 130 is independently transferred to the differential pressure sensor 150 through the path indicated by the arrow in FIG. 3, that is, the differential pressure between the voltage and the positive pressure, that is, the dynamic pressure h. This is measured. At this time, the air solenoid valve (S5) is closed, there is no inflow of air from the outside.

4 shows the open / closed state of the valve and the flow path when the differential pressure compensator 160 performs the differential pressure sensor 150 automatic zero correction function, that is, the differential pressure correction. As shown, each valve is opened and closed as in FIG. 3, and the air solenoid valve S5 is opened to supply air from the air supply port 165. That is, the first and second directions of the first three-way solenoid valve S1 are opened and the third is closed. The second three-way solenoid valve S2 also has a first side and a second side open and a third side closed. Then, the first direction side of the third three-way solenoid valve S3 is closed, and the second and third direction sides are opened. The fourth three-way solenoid valve S4 also closes the first side and opens the second and third sides.

When the air solenoid valve S5 is opened in such an open / closed state of the valve and the flow path, air is introduced through the air supply port 165. Inflowed air is moved along the air supply passage 166, and a part of the air flows through the first common passage 163 toward the first three-way solenoid valve S1 and the second three-way solenoid valve S2, and then the voltage port ( As it is discharged to the 140 and the positive pressure port 130, the exhaust gas is not allowed to flow through the voltage transfer passage 161 and the constant pressure transfer passage 162, and the discharge gas remaining in each passage after the differential pressure measurement is discharged to the outside. Do not affect later pressure measurement.

In addition, a portion of the introduced air is moved along the air supply passage 166 and branched to the third three-way solenoid valve S3 and the fourth three-way solenoid valve S4 through the second common flow path 164, respectively, and then voltage. Independently moved through the delivery channel 161 and the positive pressure transmission channel 162 is introduced into the differential pressure sensor 150. Thus, the differential pressure sensor 150 measures the differential pressure between the air flowing through the voltage transfer passage 161 and the positive pressure transfer passage 162.

Here, since the pressure of the introduced air is the same, the pressure difference of the air introduced into the differential pressure sensor 150 through the voltage transfer passage 161 and the positive pressure transfer passage 162 should be '0' in theory. However, due to an error of the differential pressure sensor 150, there is a case where the pressure difference of air does not actually become '0'. Accordingly, the controller 180 stores the actual measured air differential pressure measurement value, and subsequently measures the differential pressure of the exhaust gas by subtracting as much as the stored air differential pressure measurement value from the exhaust gas differential pressure measurement value. Correct it. In this way the correct exhaust gas differential pressure, ie the exact dynamic pressure h, can be measured.

The differential pressure measurement of the exhaust gas and the differential pressure sensor 150 correction are alternately performed at regular intervals. The autosampler according to the present invention is set such that differential pressure measurement and correction are alternately performed at intervals of 1 minute in actual application.

So far, the configuration of the main part of the autosampler according to the present invention has been described. Hereinafter, the function and operation relationship of the autosampler according to the present invention and the constant velocity suction control method using the autosampler will be described in more detail. Explain.

As shown in Figure 5, the constant velocity suction control method according to the present invention, chimney temperature measuring step (ST1); Exhaust gas sample suction transfer step (ST2); Suction flow rate, gas meter pressure, and temperature measurement step of the exhaust gas sample (ST3); Air differential pressure measuring step ST4; Exhaust gas differential pressure measuring step ST5; Exhaust gas differential pressure correcting step ST6; Exhaust gas static pressure measurement step (ST7); Exhaust gas density and flow rate calculating step (ST8); Calculating the constant velocity flow rate and comparing with the suction flow rate (ST9); And a suction flow rate adjusting step ST10. It will be described in detail below.

When the exhaust gas sampling operation is started, pressure is sensed through the voltage and positive pressure tubes of the pitot tube 2 provided in the probe, and the sensed pressure is the voltage port 140 of the autosampler through the umbilical cable 50. And is transmitted to the constant pressure port 130. The pressure transmitted to the voltage port 140 and the positive pressure port 130 is transmitted to the differential pressure sensor 150 through the voltage transfer passage 161 and the positive pressure shear passage, and the dynamic pressure h, which is the pressure difference between the voltage and the positive pressure, is measured. . The correction of the differential pressure sensor 150 is performed at regular intervals as described above.

At the same time, the chimney temperature (Ts), probe temperature (Tp), heater temperature (Th), impingement temperature (Ti) measured by the temperature sensor (3) provided in the probe through the umbilical cable (50) It is delivered to the controller 180. Then, according to the operation of the vacuum pump 125, the exhaust gas sample is sucked through the suction nozzle (1) provided in the probe and the exhaust gas sample is transferred along the sample transport pipe (120).

The exhaust gas sample transported along the sample transport pipe 120 includes the exhaust gas suction flow rate (rFlow), the gas meter pressure (Pm), and the temperature of the exhaust gas sample (Tm) flowing into the gas meter 128 from the gas meter 128. Is measured, and the measured values are transmitted to the controller 180.

Specifically, the autosampler according to the present invention is used to collect a dust sample from a discharge gas or a gas sample. Hereinafter, a method of collecting a dust sample and a gas sample will be described.

The method of collecting dust samples from the exhaust gas can be divided into the case of using the automatic mode and the case of using the manual mode. In the case of using the automatic mode, first, the first adjustment valve 123 shown in FIG. 2 is turned fully counterclockwise to fully open, and the second adjustment valve 127 is turned clockwise to be completely closed. That is, by suppressing the bypass to increase the suction amount, however, when the suction flow rate is 10 LPM or less, the vacuum pump 125 may be overwhelmed so that the second gauge valve 127 may be 40 cmHg or less. Turn it counterclockwise about one turn. When the operation is started in this state, as described later, the motor driving is controlled by the controller 180 so that the constant speed suction is performed as the opening / closing amount of the electric valve 122 is adjusted. In the method of collecting the dust sample using the manual mode, the electric valve 122 is opened as much as possible, and then the first adjustment valve 123 is fully opened in the counterclockwise direction as in the automatic mode, and the gas meter 128 The second adjustment valve 127 is adjusted so that the suction flow rate rFlow coincides with the constant velocity flow rate Qm described later.

When the gas sample is to be collected, the first adjustment valve 123 is turned clockwise to completely close the second valve, and the second adjustment valve 127 is adjusted to adjust the flow rate. That is, the sample is sucked through an orifice connected in parallel with the first adjustment valve 123, and the orifice is manufactured to pass a flow rate of about 1 to 2 liters according to the second adjustment valve 127.

On the other hand, the controller 180 receives and stores various temperature information, pressure information, and suction flow rate information transmitted from the pro part and the gas meter 128, and the exhaust gas density, exhaust gas flow rate, constant velocity flow rate, The constant velocity coefficient, the standard state conversion volume, and the like are calculated, and the electric valve 122 is controlled based on the calculated information to realize constant velocity suction, and the concentration of pollutant is calculated. The method for calculating the pollutant concentration in the controller 180 is generally performed in a conventional autosampler, and a detailed description thereof will be omitted. Hereinafter, a method for realizing constant velocity suction, which is a feature of the autosampler according to the present invention, will be described. It will be described in detail.

The controller 180 has to calculate the constant velocity flow rate Qm, which is the flow rate of the discharge gas to be actually sucked in order to realize constant velocity suction. The constant velocity flow rate Qm is calculated by equation (1).

식 (1)

Formula (1)

Qm: Suction flow rate in gas meter [LPM]

d: used suction nozzle inner diameter [mm]

V: exhaust gas flow rate measurement value [m / sec]

Xw: Volume percentage setting value of water vapor in the exhaust gas [%]

Tm: Gas meter inlet temperature measurement [℃]

Ts: Chimney temperature measurement [℃]

Pa: Atmospheric pressure setpoint or measured value [mmHg]

Ps: Static pressure measurement value of measuring point [mmHg]

Pm: Gas meter pressure measurement [mmHg]

Among the data necessary for the calculation of the constant velocity flow, the inside diameter of the suction nozzle is measured and input in advance, and the volume percentage of the water vapor in the exhaust gas is also measured and stored separately before the sampling. In addition, the suction flow rate, the gas meter inlet temperature, the chimney temperature, the static pressure, and the gas meter pressure in the gas meter 128 are measured and transmitted from the probe and the gas meter 128 to the controller 180 as mentioned above. Atmospheric pressure stores the measured value when the atmospheric pressure sensor 170 is provided, and in advance stores and stores the pressure measured from the barometer.

On the other hand, the flow velocity measurement value of the exhaust gas is required for the calculation of the constant velocity flow rate. The flow rate of the exhaust gas is calculated by the following equation (2).

식 (2)

Formula (2)

V: exhaust gas flow rate [m / sec]

C: Pitot coefficient

h: Dynamic pressure measurement [mmH20]

g: acceleration of gravity

r: exhaust gas density

Of the data necessary for calculating the flow rate of the exhaust gas, the pitot tube coefficient is a value uniquely assigned to the pitot tube 2 to be used, and it is stored in advance before being collected. In addition, the dynamic pressure measurement value is a pressure difference between the voltage and the positive pressure, measured by the differential pressure sensor 150, and transmitted to the controller 180. The dynamic pressure measurement value is measured through the automatic zero correction of the differential pressure sensor 150 described above, and thus the exhaust gas flow rate can be calculated very accurately with high accuracy.

On the other hand, the exhaust gas density is required to calculate the exhaust gas flow rate. The exhaust gas density is calculated by the following equation (3).

식 (3)

Formula (3)

r: exhaust gas density [kg / ㎥]

r _o : The set value of the wet exhaust gas density in the standard condition (0 ℃, 1atm) [kg / ㎥]

Ts: Chimney temperature measurement [℃]

Pa: Atmospheric pressure measurement [mmHg]

Ps: static pressure measurement [mmHg]

Among the data required to calculate the exhaust gas density, the standard wet humid gas density value setting value is measured or calculated in advance by an appropriate method before sampling. When using solid fuel, r _o = 1.3 [kg / ㎥]. The chimney temperature measurement value is measured from the probe, and the static pressure measurement value and the atmospheric pressure measurement value are respectively measured from the static pressure sensor 135 and the atmospheric pressure sensor 170 and transmitted to the controller 180.

From the measurement data or the preset input data as described above, the controller 180 first calculates the exhaust gas density, measures the flow rate of the exhaust gas using the calculated exhaust gas density, and then measures the exhaust gas flow rate. Finally, the constant velocity flow rate is calculated.

When the constant velocity flow rate is calculated, the controller 180 compares the calculated constant velocity flow rate with the suction flow rate measured by the gas meter 128 and transmitted in real time. As a result of the comparison, when a difference occurs between both flow rates, the controller 180 controls the motor of the electric valve 122 to adjust the open / close state of the electric valve 122. Adjustment of the open / close state of the electric valve 122 is performed until the constant velocity flow rate and the suction flow rate become equal to each other.

In this way, the so-called constant velocity suction, in which the constant velocity flow rate and the suction flow rate are equal, is realized, so that accurate analysis data can be obtained after sampling.

So far, the present invention has been described in detail with reference to embodiments of the present invention. However, the scope of the present invention is not limited thereto, and the present invention is intended to include practically equivalent ranges.

1 is a schematic diagram of a conventional exhaust gas sampling facility,

2 is a block diagram of a sampling system including an autosampler according to the present invention;

3 is a detailed configuration diagram of a differential pressure sensor and a differential pressure compensation part of an autosampler according to the present invention;

4 is an open and close state diagram of a valve and a flow path of a differential pressure compensating unit during differential pressure correction;

5 is a flow chart of a constant velocity suction control method using an autosampler according to the present invention.

Explanation of symbols on the main parts of the drawings

1: suction nozzle 2: pitot tube

3: temperature sensor 4: filter paper holder

5: impinger train 6: cooling tank

7: impinger 8: connector

9: phytomanometer 10: flow control valve

11: vacuum pump 12: gas meter

13: Orifice 14: Orifice Manometer

50: umbilical cable 100: autosampler

110: temperature signal line 120: sample transfer pipe

122: electric valve 123: first adjustment valve

124: orifice tube 125: vacuum pump

126: bypass pipe 127: second adjustment valve

128 gas meter 129 oxygen sensor

130: static pressure port 135: static pressure sensor

140: voltage port 150: differential pressure sensor

160: differential pressure compensation 161: voltage transmission path

162: static pressure delivery channel 163: first common channel

164: second common flow path 165: air supply port

166: air supply flow path 170: atmospheric pressure sensor

180: control unit

Claims (5)

As an auto sampler connected to a probe including a pitot tube (2), a suction nozzle and a temperature sensor (3) by an umbilical cable (50) to automatically collect and analyze the flue gas. A temperature signal line 110 for transmitting a chimney temperature Ts signal detected from the temperature sensor 3; A sample transfer pipe 120 through which the discharge gas sample sucked from the suction nozzle is transferred; A vacuum pump 125 installed at the sample transfer pipe 120 to provide a suction force for transferring a discharge gas sample; The suction flow rate (rFlow) of the exhaust gas sample, the gas meter pressure (Pm), and the temperature (Tm) of the exhaust gas sample flowing into the gas meter 128 are provided at the rear end of the vacuum pump 125 of the sample transfer pipe 120. A gas meter 128 for measuring; An electric valve 122 which opens and closes according to the operation of the motor and adjusts the flow rate of the exhaust gas sample conveyed through the sample conveying pipe 120; A positive pressure port 130 and a voltage port 140 which receive the positive pressure and the voltage of the exhaust gas sucked from the pitot tube 2, respectively; A constant pressure sensor 135 connected to the constant pressure port 130 to measure a static pressure of the exhaust gas; A differential pressure sensor (150) connected to the constant pressure port (130) and the voltage port (140) for measuring a dynamic pressure (h) that is a differential pressure between the positive pressure of the exhaust gas and the voltage; A differential pressure compensation unit 160 for selectively supplying air and exhaust gas to the differential pressure sensor 150 at regular intervals to correct the zero point of the differential pressure sensor 150; The differential pressure compensation unit 160 is controlled to selectively supply the discharge gas and the air to the differential pressure sensor 150, correct the exhaust gas differential pressure measurement value based on the air differential pressure measurement value, and adjust the temperature sensor 3 and the gas. Receives the measured signals from the meter 128 and the static pressure sensor 135 and the differential pressure sensor 150, calculates the exhaust gas density and the flow rate, calculates the constant velocity flow rate for the constant velocity suction based on the calculated flow rate And a control unit (180) for controlling the electric valve (122) so that the gas meter suction flow rate is equal to the constant velocity flow rate by comparing the calculated constant velocity flow rate and the suction flow rate measured from the gas meter (128). The method of claim 1, The differential pressure compensator 160 includes: a voltage transfer passage 161 connected between the voltage port 140 and the differential pressure sensor 150 to transfer the voltage of the discharge gas to the differential pressure sensor 150; A positive pressure transmission channel 162 connected between the positive pressure port 130 and the differential pressure sensor 150 to transfer the positive pressure of the exhaust gas to the differential pressure sensor 150; A first common passage 163 and a second common passage 164 connected between the voltage transfer passage 161 and the static pressure transfer passage 162, respectively; An air supply passage 166 connected to the common passages, through which air supplied from the outside is transferred; An air solenoid valve (S5) provided in the air supply passage (166) to control supply and blocking of air; It characterized in that it comprises a three-way solenoid valve (S1, S2, S3, S4) installed in each of the connection portion of the voltage transfer passage 161 and each common flow passage, and the connection portion of the constant pressure transfer passage 162 and each common flow passage, respectively. Autosampler. The method of claim 2, The controller 180 opens the air solenoid valve to supply air and simultaneously controls the opening and closing direction of the three-way solenoid valves S1, S2, S3, and S4 to introduce air into the differential pressure sensor 150, and then measures the air. The air differential pressure measured value is received, the air solenoid valve is closed to block the supply of air, and at the same time, the opening and closing direction of each of the three-way solenoid valves S1, S2, S3, and S4 is controlled so that the voltage transfer path 161 After receiving the discharged gas differential pressure measured value after flowing the exhaust gas into the differential pressure sensor 150 through the static pressure transmission passage 162, the exhaust gas according to the air differential pressure measured value is reduced from the exhaust gas differential pressure measurement value An autosampler, characterized by correcting the differential pressure. The method according to claim 1 or 2, The sample transfer pipe 120 is provided at the rear end of the electric valve 122 and a first adjustment valve 123 for manually adjusting the flow rate of dust collected in the exhaust gas sample; An orifice tube 124 connected to the electric valve 122 and the first adjustment valve 123 in parallel to transfer the gas sample in the exhaust gas; In addition, the second adjustment valve 127 for finely adjusting the flow rate is provided in the bypass pipe 126 connected in parallel to the vacuum pump 125 and used for the purpose of preventing the overload of the vacuum pump 125 when the low flow rate is collected. Autosampler, characterized in that it further comprises. As a constant velocity suction control method of the flue gas discharged by using an autosampler connected to a probe including a pitot tube (2), a suction nozzle, and a temperature sensor (3) by an umbilical cable (50), Measuring chimney temperature (Ts) with said temperature sensor (3); Sucking the exhaust gas sample from the suction nozzle using a suction force of the vacuum pump 125 and transferring the sample through the sample transfer pipe 120; Measuring a suction flow rate (rFlow), a gas meter pressure (Pm), and a temperature (Tm) of the exhaust gas sample flowing into the gas meter (128) of the exhaust gas sample transferred through the sample transport pipe (120); Supplying air to the differential pressure sensor 150 and measuring the differential pressure; Measuring the differential pressure between the static pressure and the voltage of the exhaust gas sucked from the pitot pipe (2) by the differential pressure sensor (150); Correcting the exhaust gas differential pressure by subtracting the differential pressure between the positive pressure and the voltage of the exhaust gas measured by the differential pressure sensor 150 by the differential pressure measurement value of the air; Measuring the static pressure of the exhaust gas sucked from the pitot tube (2); Receiving the measured signals from the temperature sensor (3) and the gas meter (128), and the static pressure sensor (135) and the differential pressure sensor (150), and calculating exhaust gas density and flow rate according to a predetermined calculation formula; Calculating a constant velocity flow rate for realizing constant velocity suction based on the calculated exhaust gas flow rate, and comparing the calculated constant velocity flow rate with the suction flow rate measured from the gas meter 128; And adjusting the opening and closing degree of the electric valve (122) installed in the sample transfer pipe (120) such that the gas meter suction flow rate is equal to the constant velocity flow rate.

Images