CN2585219Y - Low dilution ratio sample treatment device of smoke continuous monitoring system - Google Patents

Abstract

"Low-dilution ratio sample gas processing device for flue gas continuous monitoring system" belongs to the field of environmental pollution monitoring. On-line monitoring and metering of pollutants such as sulfur dioxide in flue gas. The utility model specifically relates to the sample gas processing part in the system. The low dilution ratio sample gas processing device is suitable for detecting the concentration of sulfur dioxide by photoelectric method or electrochemical method. The air circuit concept is unique, which can complete the detection, calibration and automatic control functions. While detecting gas concentration, measure parameters such as sample gas, air temperature and humidity, and flow rate. The dilution ratio is a random measurement value, and the change of the dilution hole does not affect the accuracy of the measurement, and the long-term operation is stable and reliable; the data such as the volume ratio of moisture in the flue gas can be measured, and the mass concentration of sulfur dioxide required by law enforcement can be directly calculated.

Description

Low-dilution ratio sample gas processing device for flue gas continuous monitoring system

technical field

The invention belongs to the field of environmental pollution monitoring. It specifically relates to the part about sample gas processing in the flue gas continuous monitoring system.

Background technique

70% of my country's energy comes from burning coal, and the flue gas emitted contains a large amount of air pollutants. Among them, sulfur dioxide is the most serious pollution to the atmospheric environment, forming acid rain, destroying the biological chain, and endangering human survival and social and economic development. In order to control the pollution of sulfur dioxide in the flue gas, the state has issued a number of regulations. Among them: designate acid rain control areas and sulfur dioxide pollution control areas within the national territory; discharge sulfur dioxide to meet standards, reduce sulfur dioxide emissions, and implement total control; collect sewage discharge fees based on sulfur dioxide emissions. It is further clearly stipulated that from January 2001 onwards, newly rebuilt and expanded boilers with a single capacity greater than 14MW must be equipped with smoke and sulfur dioxide monitoring systems at the same time. This requires a continuous flue gas monitoring system that is suitable for China's national conditions and can meet law enforcement requirements.

Looking at the flue gas continuous monitoring systems developed, researched and produced at home and abroad, they can be divided into three subsystems according to their internal functions, which are: sample gas processing system, signal detection system and data calculation management system. The following is specifically related to the sample gas treatment system. In order to detect sulfur dioxide and other air pollutants in the flue gas, according to the industry standards HJ/T75-2001 and HJ/T76-2001, the direct measurement method can be used to detect the flue gas. Due to the influence of water vapor, the measurement accuracy is difficult to grasp, so it is rarely used. Most systems use the method of extracting flue gas, extracting the flue gas from the flue, and treating it as a sample gas for testing. One is the complete extraction method, using the pump of the sample gas treatment system as the power, using the sampling gun installed on the flue gas to continuously extract a certain amount of flue gas from the flue gas, and after dust removal, cooling and dehydration, etc., a dust-free gas is formed. dry flue gas for testing. Based on the needs of continuous monitoring, the dust removal efficiency of the sample gas treatment system must reach more than 99.9%, and the dust with particles below 1 μm must be strictly filtered out; the flow rate of the sample gas should be stable, and the change of the flow rate should not be greater than ±5%; cool down Dehydration should dissolve sulfur dioxide as little as possible; also ensure that the pipeline and component connections of the sample gas treatment system do not allow air leakage. These requirements are difficult to achieve, especially if it has been running continuously for several months without stopping the machine for maintenance. The second is the dilution extraction method, which takes flue gas and air and dilutes them according to a certain volume, usually with a dilution ratio of 1:100. The diluted sample gas has no pressure on the dust removal and dehydration links, but it is even more difficult to ensure a constant dilution ratio for a long time. Because the key part of controlling the supply of flue gas is that the flue gas passes through a measuring hole with a small diameter. Practice has proved that in continuous operation, it is impossible to remove 100% of the smoke and dust, and the smoke and dust gradually adhere to the measuring hole, changing the hole diameter, which leads to the gradual increase of the dilution ratio of the flue gas. The sulfur dioxide concentration detected by the sulfur dioxide sensor is the actual concentration of the sample gas after being diluted, and the real sulfur dioxide concentration of the flue gas must be multiplied by the dilution factor during data processing. Since the dilution ratio is changing, it is obviously inappropriate to process the test data according to a fixed dilution ratio. As time goes by, the deviation from the accurate value will become larger and larger. It is not acceptable as a law enforcement measuring instrument.

Contents of the invention

First, the purpose

The invention proposes a set of dynamic sample gas processing device which automatically determines the dilution ratio. The sample gas processed by this device has wide applicability to the detection element. It can detect the concentration of sulfur dioxide in the flue gas by photoelectric method, and can also use the electrochemical sensor to detect the concentration of sulfur dioxide and other air pollutants in the flue gas. . The detection chamber of the device is provided with electrochemical sulfur dioxide and oxygen sensors, which are used to detect the electrical signal of the volume concentration of the corresponding substance in the sample gas. During the operation of the device, the temperature, humidity and flow rate of the mixed air are also measured synchronously, and the temperature, humidity and flow rate of the sample gas are measured once per second. The relevant data is obtained and processed by the computer to calculate the dilution ratio at that moment, and further participate in the calculation Finally, determine the volume concentration of sulfur dioxide and oxygen in the flue gas. This long-term continuous operation overcomes the shortcomings of the current sampling method using dilution extraction to ensure the accuracy of detection.

The volume dilution ratio of the mixture of flue gas and air is controlled between 1:10 and 1:20. Compared with the commonly used high dilution ratio, it is called a low dilution ratio sample gas treatment device here.

2. Structure and connection

Refer to Figure 1 for the connection of gas pipelines and components of the low-dilution ratio sample gas processing device, four independent parts are surrounded by double-dot dash lines, which are: A area installed next to the flue, B of the gas circuit components and electrical components of the device Area (instrument cabinet), area C with high-pressure air source and switch, and area D (detection room in the instrument cabinet) where sulfur dioxide and oxygen sensors are set. According to its function, it can be divided into five channels with different functions, specifically:

1. Flue gas extraction, dilution and transmission channel: the flue gas is taken out from the flue, diluted with air, and then sent to the instrument cabinet of the continuous monitoring system. It consists of a sampling gun (1), a solenoid valve (2), a flue gas diluter (3), and a three-core electric heating insulation pipe (4).

2. Air supply channel: Provide clean air at a certain temperature to participate in mixing into sample gas. It consists of a temperature and humidity sensor (5), a velocity measuring tube (6), a flow meter (7) and a membrane dust filter (8).

3. Sample gas detection channel: The sample gas passes through the gas sensor in the detection chamber to detect electrical signals. It consists of a temperature and humidity sensor (9), a membrane dust filter (10), a diaphragm pump (11), a velocity measuring tube (12), a sulfur dioxide sensor (13), an oxygen sensor (14) and a flow meter (15).

4. Standard gas channel: when it is necessary to calibrate the gas sensor, provide sulfur dioxide standard gas with different concentrations. It consists of a solenoid valve (16), a flow meter (17), a high-concentration sulfur dioxide standard gas cylinder (18), a low-concentration sulfur dioxide standard gas cylinder (19) and a solenoid valve (20).

5. Sampling gun filter cleaning channel: Use clean high-pressure air to blow off the dust attached to the internal filter of the sampling gun. It consists of a solenoid valve (22) and a high-pressure air source (23).

The connection between the gas pipeline and the components of the low dilution ratio sample gas processing device is as shown in Figure 1, which is characterized in that the flue gas inlet end of the sampling gun (1) is placed in the flue, and the flue gas outlet end of (1) is connected to the solenoid valve (2 ), the outlet of (2) is connected to the flue gas inlet of the flue gas diluter (3), and the sample gas outlet of (3) is connected to the first core tube end of the three-core electric heating insulation tube (4) , the other end of the core tube is connected to one end of the temperature and humidity sensor (9), the other end of (9) is connected to one end of the membrane dust filter (10), and the other end of (10) is connected to the inlet port of the diaphragm pump (11), ( The outlet of 11) is connected to one end of the velocity measuring tube (12), the other end of (12) is connected to one end of the sulfur dioxide sensor (13), the other end of (13) is connected to one end of the oxygen sensor (14), and the other end of (14) is connected to The inlet port of the flowmeter (15) and the outlet port of (15) are placed outside the instrument cabinet to be emptied; the inlet port of the membrane dust filter (8) is arranged in the instrument cabinet, and the outlet port of (8) is connected to the flowmeter (7) The inlet port, the outlet port of (7) is connected to one end of the velocity measuring tube (6), the other end of (6) is connected to one end of the temperature and humidity sensor (5), and the other end of (5) is connected to the three-core electric heating insulation tube (4) One end of the second core tube of the core tube, the other end of the core tube is connected to the air inlet port of the flue gas diluter (3); the standard gas outlet terminal of the standard gas cylinder (18) is connected to the inlet port of the flowmeter (17), ( The outlet end of 17) is connected to the inlet end of the solenoid valve (16), the outlet end of (16) is connected to one end of the third core tube of the three-core electric heating insulation pipe (4), and the other end of the core tube is connected to the flue gas diluter (3) the standard gas inlet port; the standard gas outlet port of the standard gas cylinder (19) is connected to the inlet port of the solenoid valve (20), and the outlet port of (20) is connected to the outlet port of the diaphragm pump (11); the high-pressure air The high-pressure air outlet of the source (23) is connected to the inlet of the solenoid valve (22), and the outlet of (22) is connected to the high-pressure air inlet of the sampling gun (1). That is to complete the connection of all gas system.

In Fig. 1, a temperature sensor (21) is established in the flue to measure the flue gas temperature in the flue. Establish an absolute pressure sensor (24) to measure ambient atmospheric pressure. The measurement signal is directly input to the computer to participate in the calculation, but it has nothing to do with the gas path connection.

3. Effect

In the flue gas continuous monitoring system, the sample gas processing device of the present invention can complete all functions such as detection and calibration, and realize the final detection purpose, that is, to measure dry flue gas (without moisture) under standard conditions (temperature t ₀ =0 °C, atmospheric pressure P ₀ =101.325kPa), the mass concentration of sulfur dioxide when the combustion air excess coefficient α=1.4 (or 1.7). Since the system works continuously, a set of data is measured every second, and after processing, a cumulative average value can be obtained every 10 seconds as required by the regulations, as the basis for law enforcement.

From the calculation below, it can be seen that the dry flue gas dilution ratio involved in the calculation of this device is a value calculated simultaneously, so in the long-term operation, even if the flue gas measuring hole changes the aperture due to dust accumulation, the dilution ratio will be reduced. Changes, but do not affect the accuracy of detection, which is the main purpose of the present invention.

In addition, the device measures and calculates the moisture content in the flue gas, which eliminates the need to directly install other means of measuring humidity in the flue, thereby bringing the benefits of reducing construction costs and reducing maintenance.

In order to carry out in-depth calculations, the meanings, symbols and units of the data measured and calculated by the sensors installed in the device at the first level are defined as follows: the sulfur dioxide sensor (13) directly measures the actual volume concentration _C'v (ppm) of sulfur dioxide in the sample gas ); the oxygen sensor (14) directly measures the volume percentage content y% of oxygen in the sample gas; the temperature sensors (5), (9) respectively measure the air temperature t ₂ (°C) and relative humidity B ₂ (%RH) , the temperature t ₃ (°C) and relative humidity B ₃ (%RH) of the sample gas, so as to determine the absolute humidity p ₂ (mg/mL) of the air and the absolute humidity p ₃ (mg/mL) of the sample gas; the velocimeter (6) , (12) Measure the flow velocity V ₂ (m/s) of the air and the flow velocity V ₃ (m/s) of the sample gas respectively, combined with the cross-sectional area of the velocity measuring tube, the flow Q ₂ (mL/min) and the flow rate of the air can be determined The flow rate Q ₃ (mL/min) of the sample gas, because the flow meters (7) and (15) can directly observe the flow rate of the air and the sample gas, therefore, the electrical signal of the flow rate measured by the velocity measuring tube is directly converted into the corresponding flow rate , that is, the air flow Q ₂ (mL/min) and the sample gas flow Q ₃ (mL/min), participate in the following calculations; the temperature sensor (21) measures the flue gas temperature t (°C); the absolute pressure sensor (24) measures Atmospheric pressure P (kPa).

With the above basic parameters, further calculations can achieve the ultimate goal of detection. The derivation process is simplified, and only relevant calculation formulas are listed:

a. Flue gas flow Q ₁ contained in sample gas flow Q ₃ (at t ₃ temperature) $Q_1=Q_3-\frac{{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="Y0225484400151.png"\; state="\{\{state\}\}">Q</figure-callout>}}_2\&CenterDot;(273+t_3)}{273+t_2}(\mathrm{mL}/\min )$

b. Volume Q _1H2O occupied by water in flow Q ₁

Q _1H2O ＝4.176·(273+t ₃ )·(p ₃ Q ₃ -p ₂ Q ₂ )(mL/min)

c. The volume ratio Xsw of Q _1H2O to Q ₁ $\mathrm{wxya}=\frac{Q_{1h2o}}{Q_1}$

d. Flow ratio K of dry flue gas in flow Q ₁ and sample gas flow Q ₃ (that is, the dilution ratio of dry flue gas) $K=\frac{Q_1\&Center\; Dot;(1-\mathrm{wxya})}{Q_3}$

e. The volume percentage content Y (%) of oxygen contained in the dry flue gas in the flow rate _Q1 $Y=\frac{\mathrm{the\; y}{Q}_3-20.9{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="Y0225484400151.png"\; state="\{\{state\}\}">Q</figure-callout>}}_2}{100\&CenterDot;(1-\mathrm{wxya})\&Center\; Dot;Q_1}---(\%)$

f. Combustion air excess coefficient α $\mathrm{\&alpha;}=\frac{20.9\%}{20.9\%-Y\%}$

g. Volume concentration Cv of sulfur dioxide in dry flue gas $C_v=\frac{{C^{\&prime;}}_v}{K}\left(\mathrm{ppm}\right)$

h. The mass concentration Cm of sulfur dioxide in dry flue gas corrected to the standard state $\mathrm{cm}=2.86C_v\&Center\; Dot;\frac{273P}{101.325\&Center\; Dot;(273+t)}(\mathrm{mg}/m^3)$

i. When α=1.4, the mass concentration of sulfur dioxide in dry flue gas in standard state C _m ^α=1.4 $C_m^{\mathrm{\&alpha;}=1.4}=\frac{\mathrm{\&alpha;}\&Center\; Dot;\mathrm{cm}}{1.4}(\mathrm{mg}/m^3)$

This value is the law enforcement basis for the concentration of sulfur dioxide emission in flue gas stipulated by the state.

The following analysis implements detection and calibration functions on the sample gas processing device.

1. Detection

The action of the gas circuit components: open the solenoid valve (2) and start the diaphragm pump (11).

Gas flow path: the flue gas in the flue enters the flue gas diluter (3) through the sampling gun (1) and the solenoid valve (2). The air passes through the membrane dust filter (8), flow meter (7), velocity measuring tube (6), temperature and humidity sensor (5), and enters the flue gas diluter through the second core tube of the three-core electric heating insulation tube (4) (3) Mix and dilute with flue gas to form sample gas. Then through the first core pipe of the three-core electric heating insulation pipe (4), the temperature sensor (9), the membrane dust filter (10), the diaphragm pump (11), the velocity measuring tube (12), the sulfur dioxide sensor (13), Oxygen sensor (14) and flow meter (15), sample gas are discharged outside the instrument cabinet.

Adjustment: The flow meter (15) controls the sample gas flow. A flow meter (7) controls the air flow. The needle valve of the flue gas diluter (3) controls the flue gas flow.

When the sample gas passes through each sensor, an electrical signal is output to complete the detection.

2. Calibration

After the continuous monitoring system has been in operation for a period of time, it is necessary to calibrate with sulfur dioxide standard gas to correct the "zero point" and "full scale" drift of sulfur dioxide and oxygen sensors. At the same time, the error that the sample gas processing device may absorb part of the formation of sulfur dioxide is corrected. The whole process of calibration according to regulations is divided into two parts: calibration sensor and sample gas treatment system.

(1) Calibration sensor: realize the correction of "zero point" and "full scale" drift of sulfur dioxide and oxygen sensors.

① Air cleaning pipes and sensors

The action of the gas circuit components: close the solenoid valve (2) and start the diaphragm pump (11).

Gas flow path: air passes through the membrane dust filter (8), flow meter (7), velocity measuring tube (6), temperature and humidity sensor (5), the second core tube of the three-core electric heating insulation tube (4) to the smoke Air diluter (3), then from the first core tube of the three-core electric heating insulation tube (4) through the temperature and humidity sensor (9), membrane dust filter (10), diaphragm pump (11), velocity measuring tube (12 ), sulfur dioxide sensor (13), oxygen sensor (14) and flow meter (15), then empty.

Regulation: flow meters (15), (7) control the air flow.

The purpose of this procedure is: the sulfur dioxide sensor is marked with "zero point". The oxygen sensor is marked "Full Scale", which is 20.9%.

② Low concentration sulfur dioxide standard gas calibration sensor

Use sulfur dioxide standard gas that is less than or equal to the actual range of the sulfur dioxide sensor.

The action of the gas circuit components: close the solenoid valve (2), stop the diaphragm pump (11), and open the solenoid valve (20).

Gas path flow path: low-concentration sulfur dioxide standard gas flows out from the standard gas cylinder (19), and is exhausted through the solenoid valve (20), velocity measuring tube (12), sulfur dioxide sensor (13), oxygen sensor (14) and flow meter (15). null.

Regulation: flowmeter (15) controls the standard gas flow.

The purpose of this program is: the sulfur dioxide sensor is marked with "full scale". The oxygen sensor is marked "Zero".

(2) Calibrate the channel through which the sample gas flows: Correct the error that the sample gas processing device may absorb part of the formation of sulfur dioxide.

① Air cleaning pipes and sensors

Action of air circuit components: Same as (1), ① action.

Gas flow path: same as (1), ① gas flow.

Regulation: flow meters (15), (7) control the air flow.

② High-concentration sulfur dioxide standard gas calibration sample gas channel.

Use sulfur dioxide standard gas with a concentration of more than 80% of the full scale of the instrument.

The action of the gas circuit components: close the solenoid valve (2), start the diaphragm pump (11), and open the solenoid valve (16).

Gas flow path: high-concentration sulfur dioxide standard gas flows out from the standard gas (18), passes through the flow meter (17), solenoid valve (16), and enters the flue gas through the third core tube of the three-core electric heating insulation tube (4) Diluter (3). The air enters the flue gas diluter ( 3). After the standard gas is mixed with air, it passes through the first core tube of the electric heating insulation tube (4), the temperature and humidity sensor (9), the membrane dust filter (10), the diaphragm pump (11), the velocity measuring tube (12), the sulfur dioxide sensor ( 13), oxygen sensor (14) and flow meter (15), then empty.

Regulation: The flow meter (15) controls the total flow of the mixer. A flow meter (7) controls the air flow. Flow meter (17) controls the flow of sulfur dioxide standard gas, to guarantee the dilution ratio of detection requirement.

The purpose of this program is to make corrections if sulfur dioxide is absorbed in the sample gas channel.

3. High-pressure air blows off the dust attached to the filter of the sampling gun

The built-in porous filter of the sampling gun increases with the running time, the dust attached to the filter increases, and the local resistance of the filter increases, which will change the gas operating parameters. Therefore, after running for a period of time, use high-pressure air to blow off the dust attached to the filter from the opposite direction. The control of the blowing action can be done automatically at a set time, or it can be operated manually at any time. The actions of the components are the same. First close the solenoid valve (2), then open the solenoid valve (22). The high-pressure air of the high-pressure air source (23) enters the sampling gun (1) through the electromagnetic valve (22) to realize blowing off the dust on the filter disc. The time for each blow-off is about 10 seconds, and the time interval between two blow-offs is 1-7 days, depending on the dust content in the flue gas.

4. Control the heating temperature of the three-core electric heating insulation tube. The humidity of the mixed sample gas is increased (compared to air), so as to prevent the occurrence of knots on the inner wall of the first core tube and various parts of the sample gas channel in the instrument cabinet during the sample gas transportation. Dew, until the sulfur dioxide in the sample gas is partially dissolved in water, making the detection inaccurate. It is necessary to ensure that the temperature of the sample gas is above the "dew point" without condensation.

The heating temperature of the three-core electric heating insulation pipe (4) is managed by a temperature and humidity sensor (9). Set the relative humidity of sample gas B=90% as the turning point of temperature control. When the measured B ₃ >90%, increase the heating temperature, and when the measured B ₃ <90%, reduce the heating humidity. Make the sample gas temperature t ₃ stable at the equilibrium point of B ₃ =90±2%.

Description of drawings

Figure 1. The gas pipeline and component connection diagram of the low dilution ratio sample gas processing device, which is also a summary drawing.

Fig. 2. Front sectional view of the flue gas diluter (ratio 1:1).

The codes of the components in Figure 1 and Figure 2 are explained as follows:

1. Sampling gun; 2. Solenoid valve; 3. Flue gas diluter; 4. Three-core electric heating insulation tube; 5. Temperature and humidity sensor; 6. Velocity tube; 7. Flow meter; 8. Membrane dust filter; 9 , temperature and humidity sensor; 10, membrane dust filter; 11, diaphragm pump; 12, velocity measuring tube; 13, sulfur dioxide sensor; 14, oxygen sensor; 15, flow meter; 16, solenoid valve; 17, flow meter; 18, high Concentration sulfur dioxide calibration gas; 19. Low concentration sulfur dioxide calibration gas; 20. Solenoid valve; 21. Temperature sensor; 22. Solenoid valve; 23. High pressure air source; 24. Absolute pressure sensor; 25. Flue gas inlet; 26. End cover; 27. Air inlet; 28. Shell; 29. Needle valve; 30. Needle valve seat; 31. Adjusting bolt and knob; 32. Nut; 33. Flat washer; 34. Gasket A; 35. Sample gas outlet ; 36, electric heating belt; 37, standard air inlet; 38, spacer; 39, rubber pad B.

Method to realize:

With reference to Fig. 1, Fig. 2 proposes the requirement to components and parts and processed parts, to realize the present invention. The same components are grouped into one group and numbered, and the order in each group is arranged in descending order from the code number of the components.

1. Sampling gun (1): Sampling gun is a general term for this part in the industry. The flange of this part is fixed on the outside of the flue, and a stainless steel pipe extends into the inside of the flue as a channel for extracting the flue gas from the flue. The end of the pipe is equipped with a filter plate sintered with stainless steel powder to filter out the smoke. In order to prevent the moisture in the flue gas from condensation on the filter, an electric heating belt is usually installed around the filter to heat it.

To realize the present invention, the finished product sampling gun that can be used by the complete extraction method can also be designed, processed and manufactured by itself using stainless steel materials. Specific requirements: (1) The shape of the stainless steel powder sintered filter is not limited (flat or tubular), the surface area in contact with the flue gas is not less than 30cm ² , the thickness is 2mm, the porosity is 5-15μm, and the porosity is more than 40%. (2) The electric power of the electric heating belt is 160W, and the AC 220V power supply.

2. Solenoid valve (2): Normally closed two-position two-way, non-leakage stainless steel solenoid valve. The nominal diameter is 4mm, the withstand pressure is not less than 1.0MPa, the operating temperature is not less than 150°C, and the DC 24V power supply.

3. Flue gas diluter (3): This part is designed, processed and manufactured by the device itself, and is assembled. Materials such as stainless steel and PTFE are used. Each of these components will be described later.

4. Three-core electric heating insulation tube (4): The material of the three core tubes is φ7×1mm polytetrafluoroethylene tube, arranged in a triangle, with a conductive rubber heating belt on the periphery, and the heating power is 20W per meter of core tube length, AC 220V Power supply, and the outer layer is wrapped with glass wool insulation material, with a thickness of 10mm. Self-made according to the pipe length required on site.

5. Temperature and humidity sensors (5), (9): The finished temperature and humidity sensors can be selected according to the following requirements:

a. The temperature measurement range is 0-60°C, and the accuracy is ±0.2°C;

b. Temperature measurement range 0-100% RH, accuracy ± 1% RH (0-90% RH) ± 2% RH (90-100% RH);

c. Signal: Transmitter output (current or voltage);

d. Others: low hysteresis, long-term stability, chemical corrosion resistance.

In this manual, the writing method when describing the connection is: ×× is connected to one end of the temperature and humidity sensor, and the other end is connected to ××. In the implementation, it refers to making a stainless steel hollow pipe fitting (about 60mm long) with one end closed according to the size of the probe part of the selected temperature and humidity sensor, and one stainless steel pipe joint of φ8×1.5mm is welded symmetrically on both sides. The temperature and humidity probe part is inserted into the hollow tube to ensure that the contact part between the probe part and the hollow tube is airtight and does not leak. The two joints are used as two ends for the connection of the gas circuit.

6. Speed measuring tubes (6), (12): Since the gas flow velocity in the pipeline is not greater than 1m/s, the wind velocity sensor (transmitter) that can accurately measure the air velocity close to 0m/s is selected, and it is guaranteed to be in a wide Non-directional dependence in the range and good dust resistance. You can choose the product of E+E company, model EE660 wind speed transmitter. Its measurement range is 0~1m/s, and its accuracy is 0~1m/s±(0.06m/s+2% of reading). Since the shape is basically similar to the probe of the temperature and humidity sensor, its installation is basically the same as that of the temperature and humidity sensor.

7. Flow meters (7), (15): there are needle valves to adjust the stainless steel float flow meters. Range 0.2-2.0L/min, accuracy ±1%.

8. Membrane dust filter (8), (10): The membrane dust filter is set to remove tiny dust particles. It is a one-time use replacement part. It can be replaced by a finished car gasoline filter with a polymer porous filter membrane. It can be made of a polymer material filter with a pore size of 0.5-1.0 μm, a local resistance of less than 20 mmH ₂ O (measured at a flow rate of 0.5 m/s), and a surface area of more than 50 cm ² .

9. Diaphragm pump (11): This pump is the driving source of the gas flow in the device, and a corrosion-resistant diaphragm pump is used. The requirements are: the no-load flow rate is 5.5L/min, the suction pressure is -12kPa, the head pressure is +10kPa, and the AC 220V power supply. A series of special pumps from GAST company can be selected.

10. Sulfur dioxide sensor (13): an electrochemical sulfur dioxide sensor is used. Features: Measuring range 0-100ppm, resolution 0.5ppm, output signal 0.37±0.07μA/ppm, overload range 500ppm, operating temperature -20～+50℃. The signal is output by the transmitter (current or voltage), and the sensor can be selected according to its characteristics.

11. Oxygen sensor (14): an electrochemical oxygen sensor is used. Features: Measuring range 0-100% O ₂ , resolution 0.1% O ₂ , operating temperature +5-+40°C, signal output 10.0-15.5mv. Sensors can be selected according to their characteristics.

12. Solenoid valves (16), (20), (22): normally closed two-position two-way, non-leakage stainless steel solenoid valves. Nominal diameter 4mm, withstand pressure not less than 1MPa, operating temperature 0～+60℃, DC 24V power supply.

13. Flowmeter (17): There is a stainless steel float flowmeter with a needle valve. Range 0～0.5L/min, accuracy ±1%.

14. High-concentration sulfur dioxide standard gas cylinder (18): a standard gas cylinder with a volume of 8L (including connectors). The concentration of sulfur dioxide gas in the filling is 800-1000ppm. Purchase from a standard gas manufacturer.

15. Low-concentration sulfur dioxide standard gas cylinder (19): a standard gas cylinder with a volume of 8L (including the connector). The concentration of sulfur dioxide gas inside is 90-100ppm. Purchase from a standard gas manufacturer.

16. Temperature sensor (21): adopt Pt100 or Pt1000 platinum resistance temperature sensor. The length of the armored pipe is not less than 600mm.

17. High-pressure air source (23): an air compressor unit with a pressure of 0.6-0.8MPa oil-free compressor combined with a 10L volume air storage tank, equipped with air pressure switch and safety valve. You can also use the company's pipeline high-pressure air. Therefore, it is generally referred to as a high-pressure air source in this manual.

18. Absolute pressure sensor (24): an absolute pressure transmitter product with a range of 0-110kPa, an accuracy of ±0.2%, and a signal output of 1-5V can be selected.

19. Flue gas inlet (25): the material is stainless steel rod, the material is 1Cr18Ni9Ti, and it is processed. The following parts are made of stainless steel, and the same material is used, and the repetition of materials is omitted.

20, end cap (26): the material stainless steel bar is processed and manufactured.

21. Air inlet (27): sample gas outlet (35), standard gas inlet (37): material φ8×1.5mm stainless steel pipe processing.

22. Overcoat (28): Material φ40×3.5mm stainless steel pipe is processed and manufactured.

23, needle valve (29): material polytetraoxyethylene rod processing and making.

24, needle valve seat (30): the material stainless steel bar is processed and manufactured.

25. Adjusting bolts and knobs (31): made of stainless steel rods.

26. Nut (32): Nut M8 GB54-86, standard part.

27. Flat washer drawing (33): washer 8 GB97-86, standard part.

28. Rubber pad A (34): The material is made of fluorine rubber with a temperature resistance of 250°C, and molded.

29. Electric heating belt (36): φ40×40mm annular electric heating belt. Electric power 50W, AC 220V power supply.

30, spacer cover (38): material polytetrafluoroethylene rod processing and making.

31. Rubber pad B (39): The material is made of fluorine rubber with a temperature resistance of 250°C, and molded.

32. Gas transmission connecting pipe: use φ9×2mm silicone rubber pipe as the connecting pipe between the components in the instrument cabinet.

Claims (1)

1. The low dilution ratio sample gas processing device of the flue gas continuous monitoring system is characterized in that: the flue gas inlet end of the sampling gun (1) is placed in the flue, and the flue gas outlet end of (1) is connected to the solenoid valve (2) The inlet port, the outlet port of (2) is connected to the flue gas inlet port of the flue gas diluter (3), the sample gas outlet port of (3) is connected to the end of the first core tube of the three-core electric heating insulation tube (4), the The other end of the core tube is connected to one end of the temperature and humidity sensor (9), the other end of (9) is connected to one end of the membrane dust filter (10), the other end of (10) is connected to the inlet port of the diaphragm pump (11), (11) The outlet end of the outlet is connected to one end of the velocity measuring tube (12), the other end of (12) is connected to one end of the sulfur dioxide sensor (13), the other end of (13) is connected to one end of the oxygen sensor (14), and the other end of (14) is connected to the flow rate The inlet port of the meter (15), the outlet port of (15) is placed outside the instrument cabinet to be emptied; the inlet port of the membrane dust filter (8) is arranged in the instrument cabinet, and the outlet port of (8) is connected to the inlet of the flowmeter (7) The outlet of (7) is connected to one end of the speed measuring tube (6), the other end of (6) is connected to one end of the temperature and humidity sensor (5), and the other end of (5) is connected to the three-core electric heating insulation tube (4) One end of the second core tube, the other end of the core tube is connected to the air inlet port of the flue gas diluter (3); the standard gas outlet terminal of the standard gas cylinder (18) is connected to the inlet port of the flowmeter (17), (17 ) is connected to the inlet port of the solenoid valve (16), and the outlet port of (16) is connected to one end of the third core pipe of the three-core electric heating insulation pipe (4), and the other end of the core pipe is connected to the flue gas diluter ( 3) the standard gas inlet port; the standard gas outlet port of the standard gas cylinder (19) is connected to the inlet port of the solenoid valve (20), and the outlet port of (20) is connected to the outlet port of the diaphragm pump (11); the high-pressure air source The high-pressure air outlet of (23) is connected to the inlet of the solenoid valve (22), and the outlet of (22) is connected to the high-pressure air inlet of the sampling gun (1).

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