Flue gas moisture content measuring system

Abstract

The invention provides a flue gas moisture content measuring system, which comprises a sampling tube configured to sample from a flue gas environment; the temperature and humidity sensor has self-heating and temperature control functions; the refrigeration module is used for carrying out refrigeration treatment on the passing flue gas; the water collecting bottle is used for collecting and storing condensate water generated by the refrigeration module; the flow meter unit is used for measuring the temperature, humidity and pressure parameters of the flue gas and the accumulated volume of the flue gas flowing through the flow meter unit; the flue gas measuring unit is used for measuring and analyzing the component concentration of the flue gas; the blowback system is used for performing blowback cleaning operation on the sampling tube and the humidity sensor when the measurement is finished or high-temperature and high-humidity conditions are detected; and the data processing unit is configured to receive and process data from the humidity sensor, the flowmeter unit and the flue gas measuring unit and calculate the moisture content of the flue gas according to the processing result. According to the invention, the urgent demand on accurate measurement of flue gas humidity in the fields of industrial production and environmental monitoring can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of gas detection, and in particular to a smoke moisture content measurement system. Background Art

[0002] In the field of industrial production and environmental monitoring, accurate measurement of particulate matter and gaseous pollutants in the exhaust of fixed pollution sources is crucial. This is not only related to the compliance of environmental protection regulations, but also directly affects the control and optimization of industrial production processes. In particular, the moisture content in flue gas, as a key factor affecting the concentration of pollutants and the efficiency of flue gas treatment, its accurate measurement technology has always been a hot topic of research.

[0003] In the existing technology, the measurement of flue gas moisture content mainly relies on several mature methods, including the dry-wet bulb method, the resistance-capacitance method and the condensation method. Each method has its own unique advantages and limitations.

[0004] The wet-dry bulb method measures the temperature difference between the wet bulb and the dry bulb to estimate relative humidity. This method has a wide range of applications in meteorology, environment and other fields, thanks to its high accuracy and wide applicability. However, this method also has the problems of being time-consuming, consuming a lot of manpower and material resources, and decreasing accuracy under high temperature and positive pressure flue conditions, which limits its application efficiency in certain specific industrial environments.

[0005] The RC method is a measurement method based on the quantitative relationship between moisture in flue gas and resistance and capacitance values. It has the advantages of high measurement accuracy, fast response speed, and good stability. It is especially suitable for online monitoring of complex flue gas environments. This method uses high-precision sensors and temperature compensation technology to achieve accurate measurements in a wide range of ambient temperatures, and improves the long-term effectiveness and service life of the sensor through manual backflush calibration and sintered filter sleeve designs. However, the sensitivity and accuracy of the RC method may be affected when facing some special high-temperature working conditions, such as environments containing corrosive gases or high-temperature tar, and there is a problem of voltage peaks caused by noise interference.

[0006] The condensation method directly determines the water content in the flue gas by condensing the water in the flue gas and measuring the mass of the condensed water. This method is based on physical principles and has high accuracy. However, the condensation method has poor portability and is greatly affected by external environmental factors, especially when measuring at high temperatures, the condensation efficiency decreases, resulting in unsatisfactory measurement results.

[0007] In summary, although the existing technology provides a variety of methods for measuring the moisture content of flue gas, each method has its inherent limitations and applicable conditions. Therefore, developing a flue gas moisture content measurement technology that has high precision, high stability, can adapt to complex and changing industrial environments, and is easy to carry and operate has become a technical problem that needs to be solved urgently. Summary of the invention

[0008] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a flue gas moisture content measurement system implemented by multiple methods, which can simultaneously meet the measurement of moisture content by the resistance-capacitance method and the condensation method, and can solve the urgent need for accurate measurement of flue gas humidity in the fields of industrial production and environmental monitoring.

[0009] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0010] A flue gas moisture content measurement system, comprising:

[0011] A sampling tube configured to sample from a flue gas environment and having heating and temperature control functions to prevent condensation of the flue gas during the sampling process;

[0012] A temperature and humidity sensor with self-heating and temperature control functions, wherein the humidity-sensitive element on the temperature and humidity sensor generates a capacitance change after contacting the moisture in the flue gas, and there is a definite functional relationship between the capacitance value and the moisture content in the flue gas;

[0013] A refrigeration module is used to refrigerate the passing flue gas to cause the water vapor in the flue gas to condense into water;

[0014] A water collection bottle, used to collect and store condensed water generated by the refrigeration module;

[0015] A flow meter unit, which has a temperature sensor, a humidity sensor and a pressure sensor integrated therein, and is used to measure the temperature, humidity and pressure parameters of the flue gas and the cumulative volume of the flue gas flowing through the flow meter unit;

[0016] A sampling pump is used to pump the measured flue gas to the flue gas measurement unit for component concentration analysis;

[0017] Flue gas measurement unit, used to measure and analyze the concentration of flue gas components;

[0018] Backflush system, used to perform backflush cleaning operations on the sampling tube and humidity sensor at the end of measurement or when high temperature and high humidity conditions are detected to remove residues and maintain equipment performance;

[0019] A data processing unit configured to receive and process data from the humidity sensor, the flow meter unit and the flue gas measurement unit, and calculate the moisture content of the flue gas according to the processing results;

[0020] The display unit is used to visually display the smoke moisture content data and other related information calculated and processed by the data processing unit.

[0021] A smoke moisture content measurement system provided according to the present invention also includes: a three-way valve, which is connected to the smoke measuring unit and is used to control the flow direction of the smoke; wherein the dry smoke is sent to the smoke measuring unit for component concentration measurement after using a sampling pump, and then selectively discharged outside the machine or circulated back to a part of the system for further processing or reuse through the three-way valve; and the three-way valve is also configured with a control mechanism, which automatically adjusts the exhaust path of the smoke according to a preset measurement program or real-time conditions.

[0022] According to a flue gas moisture content measurement system provided by the present invention, the backflush system includes a backflush pump, a filter and a solenoid valve; when the measurement is completed or the system detects a high temperature or high humidity alarm, the backflush pump automatically starts to send clean air into the system through the filter at a preset flow rate; when the solenoid valve is closed, clean air accumulates at the solenoid valve to form a high-pressure air mass; after the solenoid valve is opened, the high-pressure airflow is rapidly released and accelerated to a certain flow rate through a reducer nozzle arranged at the sensor position, directly blowing the humidity sensor to achieve rapid cooling and effective removal of water vapor; wherein, part of the air is extracted by the sampling pump to replace the residual flue gas in the pipeline to ensure the accuracy of subsequent measurements.

[0023] According to a flue gas moisture content measurement system provided by the present invention, when the solenoid valve is opened to release the high-pressure airflow, except for part of the air being sucked away by the sampling pump, the remaining air is blown back along the sampling tube to the working condition, and the filter element is cleaned by the high-speed airflow.

[0024] According to a smoke moisture content measurement system provided by the present invention, the sampling tube is equipped with a heating component, and the temperature setting range is 50°C to 120°C to ensure that smoke with a moisture content in the range of 0% to 40% does not condense during the sampling process;

[0025] The temperature and humidity sensor is equipped with an automatic heating control system, which automatically adjusts the heating intensity according to the real-time monitored flue gas temperature and the relative humidity value of the temperature and humidity sensor, maintaining the temperature of the area where the temperature and humidity sensor is located between 40°C and 80°C, and the relative humidity is kept in the range of 40%RH to 85%RH.

[0026] According to a flue gas moisture content measurement system provided by the present invention, the sampling tube is made of stainless steel or other high-temperature resistant and thermally conductive metal material, which is used to reduce the temperature of the high-temperature wet flue gas to ensure that the temperature of the flue gas does not exceed 80°C when it reaches the temperature and humidity sensor.

[0027] According to a smoke moisture content measurement system provided by the present invention, the specific implementation of measuring the moisture content using the resistance-capacitance method includes:

[0028] The flue relative humidity RH and flue temperature T obtained by the temperature and humidity sensor are used to calculate the saturated water vapor pressure ew at the flue temperature T using the Goff-Gratch saturated water vapor pressure equation, which is expressed as the following formula:

[0029] 1 w =10.79586(1-T / T0)-5.02808lg(T / T0)+1.50475×10 -4 [1-10 -8.2969(T / T0-1) ]+0.42873×10 -3[104.8955(1-T0 / T)] +0.78614

[0030] Among them, T0 is the triple point temperature of water, and its value is 273.16K.

[0031] According to a flue gas moisture content measurement system provided by the present invention, the saturated water vapor pressure ed at the dew point temperature is calculated by the following formula:

[0032]

[0033] According to a smoke moisture content measurement system provided by the present invention, the smoke moisture content calculation is expressed as the following formula:

[0034]

[0035] Among them, X sw is the moisture content, %; P is the flue gas pressure (absolute static pressure), kPa; e d is the saturated water vapor pressure at dew point temperature, kPa.

[0036] According to a smoke moisture content measurement system provided by the present invention, the specific implementation of measuring the moisture content by using the condensation method includes:

[0037] After passing through the temperature and humidity sensor which has been heated to a temperature not higher than 80°C, the gas continues to enter the refrigeration module. The operating temperature of the refrigeration module is set between 0°C and 4°C, so that the gas is cooled here and condensed water is produced.

[0038] A flow meter module is provided at the air outlet of the refrigeration module to detect the dew point of the gas in real time and feed the detection data back to the data processing unit so as to adjust the refrigeration temperature of the refrigeration module according to the real-time dew point condition;

[0039] The weight of the condensed water is measured by an integrated weighing device, and the water content in the flue gas is calculated in combination with the saturated water vapor in the exhaust gas, expressed as the following formula:

[0040]

[0041] Where: X sw——Volume percentage of moisture content in exhaust gas, %;

[0042] B a ——atmospheric pressure, Pa;

[0043] G w ——The amount of condensed water in the condenser, g;

[0044] P r ——Gas pressure before flow meter, Pa;

[0045] P v ——Condenser outlet saturated water vapor pressure (can be calculated based on the condenser outlet gas temperature t v From the water vapor pressure table when the air is saturated), Pa;

[0046] Q′ r ——Rotameter flowmeter reading, L / min;

[0047] t——sampling time, min;

[0048] t t ——Gas temperature before flow meter, °C;

[0049] V a ——The volume of smoke extracted under measurement conditions (V a ≈Q′ t ×t), L.

[0050] It can be seen that compared with the prior art, the system provided by the present invention has the following beneficial effects:

[0051] 1. The present invention integrates both the resistance-capacitance method and the condensation method to flexibly select the most appropriate measurement method according to different working conditions, thereby ensuring that accurate smoke moisture content data can be obtained in various complex environments. This dual guarantee greatly improves the accuracy and reliability of the measurement.

[0052] 2. The present invention adopts a unique automatic heating control method, which can automatically adjust the heating temperature according to the actual measurement requirements, so that the humidity sensor always remains within the optimal measurement range. This not only improves the accuracy of the measurement, but also ensures that the measurement results are more in line with national standards and enhances the authority and credibility of the data.

[0053] 3. The device of the present invention has a built-in back-blowing air system, which can quickly perform cooling and replacement operations in an over-temperature or high-humidity environment, effectively preventing water vapor from eroding and damaging the temperature and humidity sensor, and significantly extending the service life of the sensor. At the same time, this design also facilitates air calibration of the flue gas component unit in the working condition, reducing the tedious operation of moving the instrument out of the working condition, and greatly improving the user's convenience.

[0054] 4. The present invention not only has the function of measuring the humidity content of flue gas, but also can simultaneously measure key operating parameters such as flue gas temperature, flue gas flow rate and flue gas components, thus achieving the goal of one machine with multiple uses. This comprehensive measurement capability enables the present invention to play an important role in multiple fields and scenarios, and improves the utilization rate and cost-effectiveness of the equipment.

[0055] 5. The present invention can measure the moisture content in flue gas up to 500°C. This feature makes the present invention applicable to flue gas measurement needs in more high-temperature environments, such as thermal power generation, steel smelting and other high-temperature industrial fields, further broadening the application scope of the equipment.

[0056] 6. The present invention can ensure the accuracy and reliability of data during the measurement process by adopting a unique heating control method. This heating method not only improves the measurement accuracy, but also enhances the stability and durability of the equipment, providing users with more reliable data support.

[0057] 7. The present invention can also be used as a flue gas preprocessor, which can measure the flue gas after preprocessing, further improving the accuracy and stability of the measurement, so that the present invention can play a more important role in the flue gas measurement system and improve the performance level of the overall system.

[0058] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a schematic diagram of an embodiment of a smoke moisture content measurement system of the present invention. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0062] See also Figure 1The present invention provides a smoke moisture content measurement system, comprising:

[0063] The sampling tube is configured to sample from a flue gas environment and has heating and temperature control functions to prevent condensation of the flue gas during the sampling process.

[0064] A temperature and humidity sensor with self-heating and temperature control functions, wherein the capacitance value of the humidity sensitive element on the temperature and humidity sensor changes after contacting with the moisture in the flue gas, and there is a definite functional relationship between the capacitance value and the moisture content in the flue gas.

[0065] The refrigeration module is used to refrigerate the passing flue gas to cause the water vapor in the flue gas to condense into water.

[0066] The water collection bottle is used to collect and store the condensed water generated by the refrigeration module.

[0067] The flow meter unit has a temperature sensor, a humidity sensor and a pressure sensor integrated therein, and is used to measure the temperature, humidity and pressure parameters of the flue gas and the cumulative volume of the flue gas flowing through the flow meter unit.

[0068] The sampling pump is used to pump the measured flue gas to the flue gas measurement unit for component concentration analysis.

[0069] The flue gas measuring unit is used to measure and analyze the component concentration of the flue gas; wherein the flue gas measuring unit includes an electrochemical gas sensor.

[0070] The backflush system is used to perform backflush cleaning operations on the sampling tube and humidity sensor at the end of measurement or when high temperature and high humidity conditions are detected to remove residues and maintain equipment performance.

[0071] The data processing unit is configured to receive and process the data from the humidity sensor, the flow meter unit and the smoke measuring unit, and calculate the moisture content of the smoke according to the processing results.

[0072] The display unit is used to visually display the smoke moisture content data and other related information calculated and processed by the data processing unit.

[0073] In this embodiment, it also includes: a three-way valve, which is connected to the flue gas measuring unit and is used to control the flow direction of the flue gas; wherein, the dry flue gas is sent to the flue gas measuring unit for measurement of component concentration after using a sampling pump, and then selectively discharged outside the machine or circulated back to a part of the system for further processing or reuse through the three-way valve; and the three-way valve is also configured with a control mechanism, which automatically adjusts the exhaust path of the flue gas according to a preset measurement program or real-time conditions to ensure the accuracy of the measurement and the stable operation of the system.

[0074] In this embodiment, the backflush system includes a backflush pump, a filter and a solenoid valve; when the measurement is completed or the system detects a high temperature or high humidity alarm, the backflush pump starts automatically to send clean air into the system through the filter at a flow rate of 3L / min; when the solenoid valve is closed, clean air accumulates at the solenoid valve to form a high-pressure air mass; after the solenoid valve is opened, the high-pressure airflow is rapidly released and accelerated to about 16m / s through a reducer nozzle (the diameter at the reducer is 2mm) arranged at the sensor position, directly blowing the humidity sensor to achieve rapid cooling and effective removal of water vapor; among them, part of the air (about 1L / min) is extracted by the sampling pump to replace the residual flue gas in the pipeline to ensure the accuracy of subsequent measurements.

[0075] When the solenoid valve is opened to release the high-pressure airflow, in addition to part of the air (about 1L / min) being sucked away by the sampling pump, the remaining air (about 2L / min) is blown back along the sampling tube into the working condition, and the filter element is cleaned by the high-speed airflow. This process not only helps to quickly restore the working environment of the sensor, but also uses the high-speed airflow to clean the filter element at the front end, effectively preventing the filter element from being blocked and ensuring the long-term stable operation of the system; in addition, the operating parameters of the backflush system, including the flow rate of the backflush pump, the opening time of the solenoid valve, and the backflush frequency, can be flexibly adjusted through the control system according to actual needs to meet the measurement requirements under different working conditions.

[0076] In this embodiment, the sampling tube is built with a heating component, the setting temperature range of which is 50°C to 120°C, and the default heating temperature is 80°C, so as to ensure that the flue gas with a moisture content in the range of 0% to 40% does not condense during the sampling process;

[0077] The temperature and humidity sensor has a built-in automatic heating control system, which automatically adjusts the heating intensity according to the real-time monitored flue gas temperature and the relative humidity value of the temperature and humidity sensor, maintaining the temperature of the area where the temperature and humidity sensor is located between 40°C and 80°C, and the relative humidity is kept in the range of 40%RH to 85%RH, so as to optimize the measurement environment and improve the measurement accuracy.

[0078] In this embodiment, the sampling tube is made of stainless steel or other high-temperature resistant and thermally conductive metal material, which is used to reduce the temperature of high-temperature wet flue gas (temperature below 500°C) to ensure that the temperature of the flue gas does not exceed 80°C when it reaches the temperature and humidity sensor, thereby protecting the sensor and ensuring the accuracy of the measurement results.

[0079] Specifically, the airflow direction of this embodiment is: the flue gas containing moisture (wet flue gas) passes through the filter element and the heated sampling tube (to prevent condensation) to the position of the temperature and humidity sensor (self-heating, the control method will be described later), and the humidity sensitive element on the humidity sensor produces a capacitance change after contacting with moisture. The capacitance value and the moisture content have a certain functional relationship, and the moisture content is measured; the wet flue gas continues to flow through the refrigeration module, and condensed water is generated when it encounters cold. The gas and water are separated under the action of gravity, and the condensed water is collected by the water collection bottle. The dry flue gas flows through the flow meter unit along the pipeline. The flow meter contains temperature, humidity and pressure sensors, which measure the temperature, humidity and pressure of the dry flue gas at this time, and record the cumulative volume flowing through the sensor; the dry flue gas is blown into the flue gas measurement unit after using a pump, and its component concentration is measured, and finally discharged from the machine through the three-way valve.

[0080] When the measurement is completed or the high temperature or high humidity alarm is triggered, the 3L / min backflush pump is started. After the clean air passes through the filter and the backflush pump, a high-pressure air mass is formed at the solenoid valve. When the solenoid valve is opened, the high-pressure airflow flows out quickly. Due to the reducer nozzle at the sensor position (the diameter at the reducer is 2mm), the gas flow rate is further accelerated (the flow rate can reach about 16m / s). The humidity sensor position is used for cooling and purging water vapor. Part of the air (about 1L / min) will be drawn away by the sampling pump at the rear end to replace the flue gas in the later pipeline, and the other part of the air (about 2L / min) will be backflush along the sampling tube into the working condition, while cleaning the front-end filter element.

[0081] In this embodiment, when the system adopts the resistance-capacitance method to measure the moisture content, the flue relative humidity RH and the flue temperature T are obtained through the temperature and humidity sensor, and the saturated water vapor pressure ew at the flue temperature T is obtained by using the Goff-Grattch saturated water vapor pressure equation, and then the moisture content is calculated according to the formula in "GBT 11605-2005 Humidity Measurement Method".

[0082] Among them, the specific implementation of measuring moisture content using the resistance-capacitance method includes:

[0083] The flue relative humidity RH and flue temperature T obtained by the temperature and humidity sensor are used to calculate the saturated water vapor pressure ew at the flue temperature T using the Goff-Gratch saturated water vapor pressure equation, which is expressed as the following formula:

[0084] 1 w =10.79586(1-T / T0)-5.02808lg(T / T0)+1.50475×10 -4 [1-10 -8.2969(T / T0-1) ]+0.42873×10 -3[104.8955(1-T0 / T)] +0.78614

[0085] Among them, T0 is the triple point temperature of water, and its value is 273.16K.

[0086] The formula for calculating relative humidity is as follows:

[0087]

[0088] Where U is the relative humidity in percentage %, and ed is the saturated water vapor pressure at the dew point temperature. The saturated water vapor pressure ed at the dew point temperature is calculated using the following formula:

[0089]

[0090] The volume ratio is calculated as follows:

[0091]

[0092] Where p is the average atmospheric pressure during the sampling period, so the moisture content calculation formula is:

[0093]

[0094] Where pd is the measured flue pressure.

[0095] Therefore, the moisture content of flue gas is calculated as follows:

[0096]

[0097] Among them, X sw is the moisture content, %; P is the flue gas pressure (absolute static pressure), kPa; e d is the saturated water vapor pressure at dew point temperature, kPa.

[0098] It can be inferred from the above formula that when the system is at full scale (humidity content 40%) and the pressure is no more than 105 kPa, the dew point temperature is about 77°C, that is, no condensation water will be generated when the temperature is higher than 77°C.

[0099] The humidity sensor value (RH) is in a certain relationship with the temperature (T): Td = (237.7*ln(RH / 100)+17.27*T) / (237.7-ln(RH / 100)-17.27*T). Under the same humidity conditions, the dew point temperature (Td) is a constant, and RH is negatively correlated with T. Therefore, the temperature of the sensor position will also affect the sensor value. The standard GB / T 11605-2005 "Humidity Measurement Method" has made requirements for the temperature range and measurement range: "Under the conditions of -10℃~80℃, the measurement range of the capacitive hygrometer is 0%RH~100%RH", "In the range of 40%RH~85%RH, the repeatability should not be greater than 2%RH; the reproducibility should not be greater than 6%RH".

[0100] In summary, the temperature at the sensor should be -10℃~80℃, and the sensor value should be 40%RH~85%RH, so the data is more accurate. Experimental tests show that when the humidity is low (humidity content is less than 4%), if the temperature at the sensor is 80℃, the relative humidity RH will be distorted, resulting in a higher measured moisture content. Therefore, the temperature at the sensor location plays a decisive role in the accuracy of the measurement results.

[0101] Therefore, the sampling tube heating of this embodiment is set to 50℃~120℃, and the default is 80℃, which can meet the requirement of non-condensation of flue gas with a moisture content (0%~40%); the heating at the temperature and humidity sensor position is an automatic heating mode, which is judged according to the flue gas temperature and the relative humidity value of the temperature and humidity sensor to ensure that the temperature at the temperature and humidity sensor position is within the range of (40℃~80℃) and the relative humidity is within the range of (40%RH~85%RH), thereby improving the measurement accuracy. When high-temperature wet flue gas (less than 500℃) flows through the sampling tube, since the sampling tube is made of metal materials such as stainless steel to cool it down, the temperature is not higher than 80℃ when it reaches the temperature and humidity sensor.

[0102] In this embodiment, when the system adopts the condensation method to measure the moisture content, the moisture content is calculated by weighing the weight of the condensed water and the amount of saturated water vapor in the exhaust gas.

[0103] Among them, the specific implementation of measuring moisture content using the condensation method includes:

[0104] After passing through the temperature and humidity sensor which has been heated to a temperature not higher than 80°C, the gas continues to enter the refrigeration module. The operating temperature of the refrigeration module is set between 0°C and 4°C, so that the gas is cooled here and condensed water is produced.

[0105] A flow meter module is provided at the air outlet of the refrigeration module to detect the dew point of the gas in real time and feed the detection data back to the data processing unit so as to adjust the refrigeration temperature of the refrigeration module according to the real-time dew point condition;

[0106] The weight of the condensed water is measured by an integrated weighing device, and the water content in the flue gas is calculated in combination with the saturated water vapor in the exhaust gas, expressed as the following formula:

[0107]

[0108] Where: X sw ——Volume percentage of moisture content in exhaust gas, %;

[0109] B a ——atmospheric pressure, Pa;

[0110] G w ——The amount of condensed water in the condenser, g;

[0111] Pr ——Gas pressure before flow meter, Pa;

[0112] P v ——Condenser outlet saturated water vapor pressure (can be calculated based on the condenser outlet gas temperature t v From the water vapor pressure table when the air is saturated), Pa;

[0113] Q′ r ——Rotameter flowmeter reading, L / min;

[0114] t——sampling time, min;

[0115] t t ——Gas temperature before flow meter, °C;

[0116] V a ——The volume of smoke extracted under measurement conditions (V a ≈Q′ t ×t), L.

[0117] This method utilizes the condensation principle and precise temperature, humidity and pressure monitoring technology, combined with a real-time feedback adjustment mechanism, to ensure the high accuracy and reliability of moisture content measurement by the condensation method.

[0118] Therefore, the temperature of the gas is not higher than 80℃ when it flows through the temperature and humidity sensor. When it flows through the refrigeration module (0℃~4℃), it will produce condensed water when it encounters cold. There are also temperature, humidity and pressure sensors in the flow meter module at the outlet of the refrigeration module to detect the dew point of the gas and feed it back to the instrument to adjust the refrigeration temperature to ensure the dehydration effect. The water content is calculated by weighing the weight of the condensed water and the amount of saturated water vapor in the exhaust.

[0119] In summary, this embodiment integrates both the resistance-capacitance method and the condensation method to flexibly select the most appropriate measurement method according to different working conditions, thereby ensuring that accurate smoke moisture content data can be obtained in various complex environments. This dual guarantee greatly improves the accuracy and reliability of the measurement.

[0120] Furthermore, this embodiment adopts a unique automatic heating control method, which can automatically adjust the heating temperature according to actual measurement requirements, so that the humidity sensor always remains within the optimal measurement range. This not only improves the accuracy of the measurement, but also ensures that the measurement results are more in line with national standards and enhances the authority and credibility of the data.

[0121] Furthermore, this embodiment is provided with a back-blowing air path system, which can quickly perform cooling and replacement operations in an over-temperature or high-temperature environment, effectively preventing water vapor from corroding and damaging the temperature and humidity sensor, and significantly extending the service life of the sensor. At the same time, this design also facilitates air calibration of the flue gas component unit in the working condition, reduces the tedious operation of moving the instrument out of the working condition, and greatly improves the user's convenience.

[0122] Furthermore, this embodiment not only has the function of measuring the humidity content of flue gas, but also can simultaneously measure key operating parameters such as flue gas temperature, flue gas flow rate and flue gas composition, thus achieving the goal of one machine for multiple uses. This comprehensive measurement capability enables the present invention to play an important role in multiple fields and scenarios, and improves the utilization rate and cost-effectiveness of the equipment.

[0123] Furthermore, this embodiment can measure the moisture content in flue gas up to 500°C. This feature makes the present invention applicable to flue gas measurement needs in more high-temperature environments, such as thermal power generation, steel smelting and other high-temperature industrial fields, further broadening the application scope of the equipment.

[0124] Furthermore, this embodiment can ensure the accuracy and reliability of data during the measurement process by adopting a unique heating control method. This heating method not only improves the measurement accuracy, but also enhances the stability and durability of the equipment, providing users with more reliable data support.

[0125] Furthermore, the present embodiment can also be used as a flue gas preprocessor, which preprocesses the flue gas before measuring it, further improving the accuracy and stability of the measurement. This function enables the present invention to play a more important role in the flue gas measurement system and improves the performance level of the overall system.

[0126] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0127] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A flue gas moisture content measurement system, characterized in that: include: A sampling tube configured to sample from a flue gas environment and having heating and temperature control functions to prevent condensation of the flue gas during the sampling process; A temperature and humidity sensor with self-heating and temperature control functions, wherein the humidity-sensitive element on the temperature and humidity sensor generates a capacitance change after contacting the moisture in the flue gas, and there is a definite functional relationship between the capacitance value and the moisture content in the flue gas; A refrigeration module is used to refrigerate the passing flue gas to cause the water vapor in the flue gas to condense into water; A water collection bottle, used to collect and store condensed water generated by the refrigeration module; A flow meter unit, which has a temperature sensor, a humidity sensor and a pressure sensor integrated therein, and is used to measure the temperature, humidity and pressure parameters of the flue gas and the cumulative volume of the flue gas flowing through the flow meter unit; A sampling pump is used to pump the measured flue gas to the flue gas measurement unit for component concentration analysis; Flue gas measurement unit, used to measure and analyze the concentration of flue gas components; Backflush system, used to perform backflush cleaning operations on the sampling tube and humidity sensor at the end of measurement or when high temperature and high humidity conditions are detected to remove residues and maintain equipment performance; A data processing unit configured to receive and process data from the humidity sensor, the flow meter unit and the flue gas measurement unit, and calculate the moisture content of the flue gas according to the processing results; The display unit is used to visually display the smoke moisture content data and other related information calculated and processed by the data processing unit.

2. The system according to claim 1, characterized in that Also includes: A three-way valve, connected to the flue gas measurement unit, is used to control the flow direction of the flue gas; Among them, the dry flue gas is sent to the flue gas measurement unit for component concentration measurement after using a sampling pump, and then selectively discharged outside the machine or circulated back to a part of the system for further processing or reuse through the three-way valve; and the three-way valve is also configured with a control mechanism, which automatically adjusts the exhaust path of the flue gas according to a preset measurement program or real-time conditions.

3. The system according to claim 1, characterized in that: The backflush system includes a backflush pump, a filter and a solenoid valve; when the measurement is completed or the system detects a high temperature or high humidity alarm, the backflush pump starts automatically to send clean air into the system through the filter at a preset flow rate; when the solenoid valve is closed, clean air accumulates at the solenoid valve to form a high-pressure air mass; after the solenoid valve is opened, the high-pressure airflow is quickly released and accelerated to a certain flow rate through a reducer nozzle set at the sensor position, directly blowing the humidity sensor to achieve rapid cooling and effective removal of water vapor; wherein, part of the air is extracted by the sampling pump to replace the residual flue gas in the pipeline to ensure the accuracy of subsequent measurements.

4. The system according to claim 3, characterized in that: When the solenoid valve opens to release the high-pressure airflow, except for part of the air being sucked away by the sampling pump, the remaining air is blown back along the sampling tube into the working condition, and the filter element is cleaned by the high-speed airflow.

5. The system according to claim 1, characterized in that: The sampling tube is equipped with a heating component, the temperature of which is set in the range of 50°C to 120°C to ensure that the flue gas with a moisture content in the range of 0% to 40% does not condense during the sampling process; The temperature and humidity sensor is equipped with an automatic heating control system, which automatically adjusts the heating intensity according to the real-time monitored flue gas temperature and the relative humidity value of the temperature and humidity sensor, maintaining the temperature of the area where the temperature and humidity sensor is located between 40°C and 80°C, and the relative humidity is kept in the range of 40%RH to 85%RH.

6. The system according to claim 5, characterized in that: The sampling tube is made of stainless steel or other high temperature resistant and thermally conductive metal material, and is used to reduce the temperature of the high temperature wet flue gas to ensure that the temperature of the flue gas does not exceed 80°C when it reaches the temperature and humidity sensor.

7. The system according to any one of claims 1 to 6, characterized in that: The specific implementation of measuring moisture content using the resistance-capacitance method includes: The flue relative humidity RH and flue temperature T obtained by the temperature and humidity sensor are used to calculate the saturated water vapor pressure ew at the flue temperature T using the Goff-Gratch saturated water vapor pressure equation, which is expressed as the following formula: lge w =10.79586(1-T / T0)-5.02808lg(T / T0)+1.50475×10 -4 [1-10 -8.2969(T / T0-1) ]+0.42 873×10 -3[104.8955(1-T0 / T)] +0.78614 Among them, T0 is the triple point temperature of water, and its value is 273.16K.

8. The system according to claim 7, characterized in that: The saturated water vapor pressure ed at the dew point temperature is calculated by the following formula:

9. The system according to claim 8, characterized in that: The moisture content of flue gas is calculated as follows: Among them, X sw is the moisture content, %; P is the flue gas pressure (absolute static pressure), kPa; e d is the saturated water vapor pressure at dew point temperature, kPa.

10. The system according to any one of claims 1 to 6, characterized in that: The specific implementation of moisture content measurement using the condensation method includes: After passing through the temperature and humidity sensor which has been heated to a temperature not higher than 80°C, the gas continues to enter the refrigeration module. The operating temperature of the refrigeration module is set between 0°C and 4°C, so that the gas is cooled here and condensed water is produced. A flow meter module is provided at the air outlet of the refrigeration module to detect the dew point of the gas in real time and feed the detection data back to the data processing unit so as to adjust the refrigeration temperature of the refrigeration module according to the real-time dew point condition; The weight of the condensed water is measured by an integrated weighing device, and the water content in the flue gas is calculated in combination with the saturated water vapor in the exhaust gas, expressed as the following formula: Where: X sw ——Volume percentage of moisture content in exhaust gas, %; B s ——atmospheric pressure, Pa; G w ——The amount of condensed water in the condenser, g; P r ——Gas pressure before flow meter, Pa; P v ——Condenser outlet saturated water vapor pressure (can be calculated based on the condenser outlet gas temperature t v From the water vapor pressure table when the air is saturated), Pa; Q t ——Rotameter flowmeter reading, L / min; l——sampling time, min; t t ——Gas temperature before flow meter, °C; V a ——The volume of smoke extracted under measurement conditions (V a ≈Q′ t ×t), L.

Images