Humidity measuring instruments are widely used in the process industry - power, chemical, pharmaceutical, water treatment and other fields, and are an important part of field instruments. Personalized on-site conditions are increasingly demanding for the selection of suitable humidity measuring instruments. This article describes the application of several types of instruments produced by the British Thickener Instrument Co., Ltd. in the power, chemical, pharmaceutical and water treatment industries.
Detection of Moisture Content in SF6 Gas in High-Voltage Switches in the Power Industry In power distribution networks with voltage delivery (100 kV to 400 kV), power switch or load current interruption is often caused by an arc between two contact points. SF6 is insulated, with pressure SF6 can effectively control the formation of the arc. However, with the passage of time, the entry of moisture causes the SF6 to decompose into other products such as fluorine hydrides. This will not only affect the operating performance of a single device, but also when the moisture content is high, the by-products will also include highly corrosive hydrogen fluoride, will accelerate the corrosion of the switch contacts, cause physical damage, and will spread to the circuit breaker Other areas in the enclosure increase the damage level and cause safety hazards to people and equipment.
Before use, the moisture content of the new bottled SF6 supplied by the industrial gas supplier should first be checked, and before the circuit breaker provided by the circuit breaker manufacturer is used, it should also be checked beforehand. During storage of the SF6 bottled air, moisture can easily enter from the inlet. If it is well-preserved, the moisture content of SF6 should be <10 ppmv, which is equivalent to an atmospheric dew point of <-60°C. At the circuit-breaker manufacturer, dry air is used to purge the circuit-breaker housing during internal maintenance work at the final stage or before pressure is applied and sealed with SF6. The most common practice is to use bottled, high-purity nitrogen or other inert gases, which are purged with moisture through repeated pressurization until the moisture content in the enclosure drops to 10 ppmV, which corresponds to an atmospheric dewpoint of <-60°C. For on-site inspections/continuous monitoring, the moisture content in SF6 must be controlled to <100 ppmv, which is equivalent to an atmospheric dew point <-42°C.
The Cermax portable dew point meter (see Figure 1) can be used for inspection of bottled gas or for drying before the circuit breaker shell is filled. This wide measuring range of the instrument provides fast and accurate measurements. A secondary menu can be used to select a secondary input, ie manual setting or signal input gas pressure, then the ppmv units of SF6 can be displayed and the built-in data acquisition function can be used. Store 10,000 measurement results and then download the stored data to the host by using Windows HyperTerminal or similar data transfer system. The above instruments can also be used for on-site rapid detection of SF6 gas in the circuit breaker housing. The sample can be taken out, the sample gas can be returned for continued use, or discharged into the atmosphere, and a quick measurement means that less sample gas is consumed. For continuous online measurements, a Cermet II dewpoint meter can be used. This instrument needs to be supplied with mains power, or use Transmet dew point transmitter, 24V DC, output signal is 4 ~ 20mA or RS232/RS485 signal, so the signal can be input into a computer central processing system, suitable for multiple measurement points installation. Note that the sensor must be installed in the upper part of the circuit breaker enclosure to avoid accumulating more and more particulate contaminants in the enclosure. For measurements that require high stability and accuracy, a cold mirror dew point meter, the S4000 Integrale (see Figure 2), can be selected. The measurement range is -60°C, and multiple engineering units can be displayed, including ppmv for SF6. The measurement accuracy is ±0.1°C, and the response speed at -40°C dew point is approximately 10 minutes. The most accurate measurement can be obtained with minimal sample consumption.
Hydrogen content in cooling hydrogen for power generation units The thermal conductivity of hydrogen is much higher than in other gases. Therefore, in the power generation industry, the conventional method is to use hydrogen to directly cool the stator windings of the generator set. Because the casing of the generator set cannot be sealed, the moisture in the surrounding air is likely to invade into the set, and the heat exchanger will create gaps due to aging, and moisture will also leak into the hydrogen. Therefore, the circulation loop of hydrogen must be equipped with a desiccant dryer to continuously remove the absorbed moisture. Otherwise, the moisture in the hydrogen will cause the exposed metal parts to condense and cause flashover and even lead to heavy losses. If the dew point of hydrogen exceeds the upper limit, emergency measures should be taken immediately, or the generator should be stopped and repaired, or the pump should be immediately restarted and the dry hydrogen gas pumped into the system.
The British company Michell's TransmetIS transmitter can install the ceramic humidity sensing part on the sampling device and perform continuous on-line measurement at the outlet of the generator set and the outlet of the hydrogen adsorption dryer. Measurements should be made at system pressure full scale to accurately provide information on whether condensation will occur under genset conditions. TransmetIS transmitters have a CENELEC approval certificate for dew point measurement of combustible gases in hazardous areas. Due to the danger of hydrogen explosion, the digital display should be located away from the generator set and installed in a designated safe location. The sensing probe cable assembly should be equipped with a current barrier. The monitor has a full-featured display and analog output, and configures two alarms set by the user. The meter can be set in the "warning" and "stop immediately" states. TransmetIS transmitters can provide 4-20mA or 0-20mA analog signals to the control room. Michell Intrinsic portable dew point hygrometer CermaxIS can be used as a site inspection tool. Rapid response and easy operation (with data logging) allow users to perform gas analysis quickly.
Water treatment systems The water treatment industry has increasingly used ozone (O3) instead of chlorine to treat purified water. There are four main applications: drinking water, food production water, pharmaceutical production water, swimming pool water, and disinfection before putting the sewage into the circulation. The chlorination process is not only costly but also poses risks to health and safety in water transport and chlorination system applications. In view of this, the water treatment industry has consistently used ozone disinfection in recent years. Ozone and chlorinated water have the same water treatment effect. They are powerful oxidizing media and can attack impurities in water (especially for microbial media). They can be split into harmless residues and filtered out of the water system. The advantage of ozone is that after acting on microorganisms, it will split into completely harmless oxygen atoms.
The working principle of the ozone generator is very simple. Pure air or oxygen is discharged through the high voltage (usually 12000V) between the two electrodes of the reaction unit (ceramic or stainless steel), and a high voltage causes a reaction between oxygen atoms to form a stable ozone molecule. A typical ozone generator must use compressed air from a standard regenerative dryer, from a set of reaction vessels such as a heat exchanger, to the ozone generator. The following three necessary reasons determine the measurement of the moisture in the air or oxygen of the process: preventing arcing at the generator electrode, preventing corrosion of system components due to acid formation, and increasing the ozonation efficiency. If there is a lot of moisture in the gas entering the generator, it will cause the electrode to produce an arc, and in extreme cases, the event of the electrode touching the wall of the cavity will occur. The arc will damage the electrodes and the system's casing, eventually leading to system paralysis and expensive maintenance costs. The side effects of arcing in the presence of ozone can cause nitrogen and water to generate acids and other nitrogen compounds that can cause electrode and system components to corrode, which can also cause ozone generator defects. The efficiency of the ozone generator is inversely proportional to the moisture content of the input gas. If the moisture content is reduced from 50 ppm to 5 ppm (-50 to -70°C dew point), the efficiency of the generator can be increased by 20%. General technical specifications stipulate that the minimum dew point of the input air or oxygen is -50°C, but if accurate control of drying can be achieved to a dew point of -70°C, then the generator's work efficiency and life can be significantly improved. Improve and improve.
Michell's Impedance Hygrometer can be used to monitor the moisture content of the input gas. On-line measurement instruments include the Easidew Transmitter, Easidew Online, Transmet or Cermet II, and site-specific detection with Easidew or Cermax portable. Michell Instruments online hygrometer and drying control system combined to ensure that the input gas is as dry as possible to maintain the generator's high efficiency and working life.
Pharmaceutical industry Dew point temperature of dry air in this industry is very low. When the fluid air bed system dries the compound, the dew point is generally required to be -40°C. In addition, moisture must be prevented from re-creating during the cooling period before the material is packaged. All these occasions require precise controlled, reproducible environmental conditions and traceability. In most cases, the user will select the relative humidity sensor, but if it is to be accurately controlled in the range of 2% or 1.5%, it is at the critical point of measurement accuracy of such instruments or exceeds the measurement capability of the instrument. So the best solution is to use an Optidew (see Figure 3) or S4000 Integrale with an accuracy of ±0.1 to 0.2°C (depending on the required accuracy), a ±1°C dew point of Cermet II or Transmet, and a dew point of ±2°C. EasidewOnline (see Figure 4) or Easidew Transmitters. These meters provide accurate humidity measurements for precise control of the dehumidifier.
Catalytic Reforming of Petroleum Products in the Petrochemical Industry In the catalytic reforming process of refined petroleum products, it is crucial to control the moisture in recycled hydrogen in order to ensure the operating efficiency of the plant. Excessive moisture content, such as greater than 50 ppmv, can lead to catalyst poisoning, which means increased costs. In addition, if the moisture in the recycle gas is not maintained in the optimal range of 20-30 ppmv, the efficiency of the chemical reaction will be reduced, and the product yield will also be affected. At this stage, in order to regularly regenerate and adjust the catalyst, hydrogen chloride must be injected into the gas stream to supplement the hydrogen content during the refining process. Humidity transmitters should be isolated from the process sampling gas to avoid the erosion of hydrogen chloride and the simultaneous increase in moisture content. The moisture content can be as high as 2000 ppmv or even higher.
TransmetIS was installed in a simple sampling system made of high-quality stainless steel components using British Michell's ceramic humidity transmitter. The sampling system should be equipped with inlet and outlet valves to isolate the transmitter during the regeneration phase so that the transmitter is only exposed to traces of hydrogen chloride during pressurized drying. CermetIIIS can be used if the application requires remote or on-site display. The transmitter operates at process pressure and indicates dew point temperature or moisture content (ppmv) under actual pipe pressure conditions. If it is necessary to display and output the humidity unit, and the transmitter is still working under the pressure of the pipeline (you can manually input a fixed pressure value into the humidity meter, or use the optional pressure transmitter option for automatic pressure compensation), The standard configuration of the Cermet II Hygrometer allows the user to select from multiple ppmv ranges. Can also choose other humidity units °C, °F, gm-3, Lb/mmscf and so on.
Before the PET industry injects PET into a mold press, it must go through processes such as drying and extrusion to achieve the purpose of improving the appearance and quality of the finished product by reducing the free moisture content. Precise control of the drying process is the first step in ensuring product quality (strength and aesthetics) is not negligible. In the solid state, PET absorbs the moisture in the air until it equilibrates with the moisture in the atmosphere. This hygroscopic behavior means that 0.6% of its weight is moisture. To ensure the performance of the polyester product, the moisture content must be reduced to 0.003% (30ppm) before heating. Because during the heating stage, the contained water will rapidly hydrolyze this raw material, thereby reducing the molecular weight and impairing the physical properties of the polyester product. The process is carried out in a hopper-loading pedestal that is processed by a hot dry air stream from a dehumidifying dryer. The general process is to expose these raw materials to air with a dew point temperature below -40°C for a period of time. Then it is carried into another funnel and passed to the mold press. A typical production plant will have 10 to 50 such dryers and mold presses.
The British company Michell's Cermet II can be used to monitor a single dryer, so that the supply of air is better than the specified dewpoint limit temperature of -40 °C. Alarms can also be used to alert technical maintenance personnel when dryer conditions deteriorate. The sensor probe should be installed at the air inlet of the dryer for measurement and above the debris feed. Transmet can also be used to output 4-20mA or 0-20mA analog signals for PLC controlled air drying systems. The Cermax portable dewpoint meter measures the efficiency of the dryer under operating load conditions. It is also possible to perform on-site inspections at normal intervals to provide high-efficiency guarantees for improving product quality and reducing costs. It is easy to operate, responds quickly to air sources below -40°C dew point, and maintainers can perform cost-effective monitoring of multiple dryers within the required period of time.
Detection of Moisture Content in SF6 Gas in High-Voltage Switches in the Power Industry In power distribution networks with voltage delivery (100 kV to 400 kV), power switch or load current interruption is often caused by an arc between two contact points. SF6 is insulated, with pressure SF6 can effectively control the formation of the arc. However, with the passage of time, the entry of moisture causes the SF6 to decompose into other products such as fluorine hydrides. This will not only affect the operating performance of a single device, but also when the moisture content is high, the by-products will also include highly corrosive hydrogen fluoride, will accelerate the corrosion of the switch contacts, cause physical damage, and will spread to the circuit breaker Other areas in the enclosure increase the damage level and cause safety hazards to people and equipment.
Before use, the moisture content of the new bottled SF6 supplied by the industrial gas supplier should first be checked, and before the circuit breaker provided by the circuit breaker manufacturer is used, it should also be checked beforehand. During storage of the SF6 bottled air, moisture can easily enter from the inlet. If it is well-preserved, the moisture content of SF6 should be <10 ppmv, which is equivalent to an atmospheric dew point of <-60°C. At the circuit-breaker manufacturer, dry air is used to purge the circuit-breaker housing during internal maintenance work at the final stage or before pressure is applied and sealed with SF6. The most common practice is to use bottled, high-purity nitrogen or other inert gases, which are purged with moisture through repeated pressurization until the moisture content in the enclosure drops to 10 ppmV, which corresponds to an atmospheric dewpoint of <-60°C. For on-site inspections/continuous monitoring, the moisture content in SF6 must be controlled to <100 ppmv, which is equivalent to an atmospheric dew point <-42°C.
The Cermax portable dew point meter (see Figure 1) can be used for inspection of bottled gas or for drying before the circuit breaker shell is filled. This wide measuring range of the instrument provides fast and accurate measurements. A secondary menu can be used to select a secondary input, ie manual setting or signal input gas pressure, then the ppmv units of SF6 can be displayed and the built-in data acquisition function can be used. Store 10,000 measurement results and then download the stored data to the host by using Windows HyperTerminal or similar data transfer system. The above instruments can also be used for on-site rapid detection of SF6 gas in the circuit breaker housing. The sample can be taken out, the sample gas can be returned for continued use, or discharged into the atmosphere, and a quick measurement means that less sample gas is consumed. For continuous online measurements, a Cermet II dewpoint meter can be used. This instrument needs to be supplied with mains power, or use Transmet dew point transmitter, 24V DC, output signal is 4 ~ 20mA or RS232/RS485 signal, so the signal can be input into a computer central processing system, suitable for multiple measurement points installation. Note that the sensor must be installed in the upper part of the circuit breaker enclosure to avoid accumulating more and more particulate contaminants in the enclosure. For measurements that require high stability and accuracy, a cold mirror dew point meter, the S4000 Integrale (see Figure 2), can be selected. The measurement range is -60°C, and multiple engineering units can be displayed, including ppmv for SF6. The measurement accuracy is ±0.1°C, and the response speed at -40°C dew point is approximately 10 minutes. The most accurate measurement can be obtained with minimal sample consumption.
Hydrogen content in cooling hydrogen for power generation units The thermal conductivity of hydrogen is much higher than in other gases. Therefore, in the power generation industry, the conventional method is to use hydrogen to directly cool the stator windings of the generator set. Because the casing of the generator set cannot be sealed, the moisture in the surrounding air is likely to invade into the set, and the heat exchanger will create gaps due to aging, and moisture will also leak into the hydrogen. Therefore, the circulation loop of hydrogen must be equipped with a desiccant dryer to continuously remove the absorbed moisture. Otherwise, the moisture in the hydrogen will cause the exposed metal parts to condense and cause flashover and even lead to heavy losses. If the dew point of hydrogen exceeds the upper limit, emergency measures should be taken immediately, or the generator should be stopped and repaired, or the pump should be immediately restarted and the dry hydrogen gas pumped into the system.
The British company Michell's TransmetIS transmitter can install the ceramic humidity sensing part on the sampling device and perform continuous on-line measurement at the outlet of the generator set and the outlet of the hydrogen adsorption dryer. Measurements should be made at system pressure full scale to accurately provide information on whether condensation will occur under genset conditions. TransmetIS transmitters have a CENELEC approval certificate for dew point measurement of combustible gases in hazardous areas. Due to the danger of hydrogen explosion, the digital display should be located away from the generator set and installed in a designated safe location. The sensing probe cable assembly should be equipped with a current barrier. The monitor has a full-featured display and analog output, and configures two alarms set by the user. The meter can be set in the "warning" and "stop immediately" states. TransmetIS transmitters can provide 4-20mA or 0-20mA analog signals to the control room. Michell Intrinsic portable dew point hygrometer CermaxIS can be used as a site inspection tool. Rapid response and easy operation (with data logging) allow users to perform gas analysis quickly.
Water treatment systems The water treatment industry has increasingly used ozone (O3) instead of chlorine to treat purified water. There are four main applications: drinking water, food production water, pharmaceutical production water, swimming pool water, and disinfection before putting the sewage into the circulation. The chlorination process is not only costly but also poses risks to health and safety in water transport and chlorination system applications. In view of this, the water treatment industry has consistently used ozone disinfection in recent years. Ozone and chlorinated water have the same water treatment effect. They are powerful oxidizing media and can attack impurities in water (especially for microbial media). They can be split into harmless residues and filtered out of the water system. The advantage of ozone is that after acting on microorganisms, it will split into completely harmless oxygen atoms.
The working principle of the ozone generator is very simple. Pure air or oxygen is discharged through the high voltage (usually 12000V) between the two electrodes of the reaction unit (ceramic or stainless steel), and a high voltage causes a reaction between oxygen atoms to form a stable ozone molecule. A typical ozone generator must use compressed air from a standard regenerative dryer, from a set of reaction vessels such as a heat exchanger, to the ozone generator. The following three necessary reasons determine the measurement of the moisture in the air or oxygen of the process: preventing arcing at the generator electrode, preventing corrosion of system components due to acid formation, and increasing the ozonation efficiency. If there is a lot of moisture in the gas entering the generator, it will cause the electrode to produce an arc, and in extreme cases, the event of the electrode touching the wall of the cavity will occur. The arc will damage the electrodes and the system's casing, eventually leading to system paralysis and expensive maintenance costs. The side effects of arcing in the presence of ozone can cause nitrogen and water to generate acids and other nitrogen compounds that can cause electrode and system components to corrode, which can also cause ozone generator defects. The efficiency of the ozone generator is inversely proportional to the moisture content of the input gas. If the moisture content is reduced from 50 ppm to 5 ppm (-50 to -70°C dew point), the efficiency of the generator can be increased by 20%. General technical specifications stipulate that the minimum dew point of the input air or oxygen is -50°C, but if accurate control of drying can be achieved to a dew point of -70°C, then the generator's work efficiency and life can be significantly improved. Improve and improve.
Michell's Impedance Hygrometer can be used to monitor the moisture content of the input gas. On-line measurement instruments include the Easidew Transmitter, Easidew Online, Transmet or Cermet II, and site-specific detection with Easidew or Cermax portable. Michell Instruments online hygrometer and drying control system combined to ensure that the input gas is as dry as possible to maintain the generator's high efficiency and working life.
Pharmaceutical industry Dew point temperature of dry air in this industry is very low. When the fluid air bed system dries the compound, the dew point is generally required to be -40°C. In addition, moisture must be prevented from re-creating during the cooling period before the material is packaged. All these occasions require precise controlled, reproducible environmental conditions and traceability. In most cases, the user will select the relative humidity sensor, but if it is to be accurately controlled in the range of 2% or 1.5%, it is at the critical point of measurement accuracy of such instruments or exceeds the measurement capability of the instrument. So the best solution is to use an Optidew (see Figure 3) or S4000 Integrale with an accuracy of ±0.1 to 0.2°C (depending on the required accuracy), a ±1°C dew point of Cermet II or Transmet, and a dew point of ±2°C. EasidewOnline (see Figure 4) or Easidew Transmitters. These meters provide accurate humidity measurements for precise control of the dehumidifier.
Catalytic Reforming of Petroleum Products in the Petrochemical Industry In the catalytic reforming process of refined petroleum products, it is crucial to control the moisture in recycled hydrogen in order to ensure the operating efficiency of the plant. Excessive moisture content, such as greater than 50 ppmv, can lead to catalyst poisoning, which means increased costs. In addition, if the moisture in the recycle gas is not maintained in the optimal range of 20-30 ppmv, the efficiency of the chemical reaction will be reduced, and the product yield will also be affected. At this stage, in order to regularly regenerate and adjust the catalyst, hydrogen chloride must be injected into the gas stream to supplement the hydrogen content during the refining process. Humidity transmitters should be isolated from the process sampling gas to avoid the erosion of hydrogen chloride and the simultaneous increase in moisture content. The moisture content can be as high as 2000 ppmv or even higher.
TransmetIS was installed in a simple sampling system made of high-quality stainless steel components using British Michell's ceramic humidity transmitter. The sampling system should be equipped with inlet and outlet valves to isolate the transmitter during the regeneration phase so that the transmitter is only exposed to traces of hydrogen chloride during pressurized drying. CermetIIIS can be used if the application requires remote or on-site display. The transmitter operates at process pressure and indicates dew point temperature or moisture content (ppmv) under actual pipe pressure conditions. If it is necessary to display and output the humidity unit, and the transmitter is still working under the pressure of the pipeline (you can manually input a fixed pressure value into the humidity meter, or use the optional pressure transmitter option for automatic pressure compensation), The standard configuration of the Cermet II Hygrometer allows the user to select from multiple ppmv ranges. Can also choose other humidity units °C, °F, gm-3, Lb/mmscf and so on.
Before the PET industry injects PET into a mold press, it must go through processes such as drying and extrusion to achieve the purpose of improving the appearance and quality of the finished product by reducing the free moisture content. Precise control of the drying process is the first step in ensuring product quality (strength and aesthetics) is not negligible. In the solid state, PET absorbs the moisture in the air until it equilibrates with the moisture in the atmosphere. This hygroscopic behavior means that 0.6% of its weight is moisture. To ensure the performance of the polyester product, the moisture content must be reduced to 0.003% (30ppm) before heating. Because during the heating stage, the contained water will rapidly hydrolyze this raw material, thereby reducing the molecular weight and impairing the physical properties of the polyester product. The process is carried out in a hopper-loading pedestal that is processed by a hot dry air stream from a dehumidifying dryer. The general process is to expose these raw materials to air with a dew point temperature below -40°C for a period of time. Then it is carried into another funnel and passed to the mold press. A typical production plant will have 10 to 50 such dryers and mold presses.
The British company Michell's Cermet II can be used to monitor a single dryer, so that the supply of air is better than the specified dewpoint limit temperature of -40 °C. Alarms can also be used to alert technical maintenance personnel when dryer conditions deteriorate. The sensor probe should be installed at the air inlet of the dryer for measurement and above the debris feed. Transmet can also be used to output 4-20mA or 0-20mA analog signals for PLC controlled air drying systems. The Cermax portable dewpoint meter measures the efficiency of the dryer under operating load conditions. It is also possible to perform on-site inspections at normal intervals to provide high-efficiency guarantees for improving product quality and reducing costs. It is easy to operate, responds quickly to air sources below -40°C dew point, and maintainers can perform cost-effective monitoring of multiple dryers within the required period of time.
Lawn Mower,Zero Turn Mowers,Riding Lawn Mower,Electric Lawn Mower
NINGBO LUBAN ELECTRIC POWER TOOLS CO.,LTD. , https://www.aye-group.com