Abstract : The paper introduces the measurement technology and products of solid mass flow of pulverized coal, summarizes the application of the solid mass flow meter in the process of pulverized coal gas transmission, discusses the test calibration method and results of the capacitive solid flow meter on an industrial scale, and Two-phase flow industry online measurement provides a reference.
Keywords: Capacitive solid mass flowmeter Gas-solid two-phase flow measurement Nuclear radiation powder coal gasification is one of the latest technologies in clean coal technology. The pulverized coal gasification process is characterized by Shell, GSP, aerospace furnaces, etc., which are characterized by continuous feed of pulverized coal and pressurized continuous operation. This type of process has the characteristics of pure oxygenation, dense phase pneumatic conveying of powdered coal, and liquid slagging. It has high efficiency of cold gas, wide adaptability of coal, high carbon conversion rate, high degree of automation, large production capacity, and good gas quality. Can meet environmental protection requirements, with strong technical advantages [1].
The flow rate of pulverized coal in pulverized coal gasification process is an important parameter concerning the stability and safe operation of the system. The pulverized coal mass flow meter is the key instrument. At present, the measurement of dry-powder dense-phase transportation can be roughly divided into two types: capacitive and radiant, mainly Thermo Fisher (formerly American Thermal Power Company, mainly found in Shell) and Swell (SWR, Germany). ), Germany Berto and France EDITFLOW and so on.
1 Solid mass flow measurement technology and products 1.1 Capacitance The measurement technology is widely used, representative of Thermo Fisher and the German SWR. In essence, SWR's solids flowmeters and Thermo Fisher's capacitive solids mass flowmeters are based on the same technology and are similar in their measurement of pressure, concentration, sensitivity, and accuracy.
1.1.1 Measurement Principle Capacitance plates are installed outside the flow pipe. When the gas-solid ratio in the pipe changes, the dielectric constant changes accordingly, causing a change in capacitance. Measure the capacitance between the plates, and then convert the digital signal to obtain the phase concentration in the pipe. Figure 1 shows the capacitor plate system.
The speed sensor consists of two capacitive sensors. The distance between the two sensors is 8mm. The solid particles pass through two sensors in sequence. Ideally, the flow pattern of the solid material does not change after a short distance. The two sensors can capture the same material flow pattern signal. The solid particle velocity can be calculated from the time difference between the signals [2].
According to the ratio of material quality to capacitance, the concentration of the material is measured by measuring the change in capacitance, and the speed of the material is measured by the cross-correlation model (the measurement basis is still the change in capacitance). The mass mass flow calculation formula is:
Q=CAVK
In the formula, Q is the mass flow rate, kg/s; C is the solid mass concentration, kg/m3; A is the cross-sectional area of ​​the sensor, m2; V is the average solid flow rate, m/s; K is the correction factor, no dimension.
Thermo Fisher Scientific's solid mass flow meter consists of the concentration meter DC13, speedometer DK13, secondary meter MT2109 or MT2107 (optional when PID regulation is required).
The instrument processes the concentration and speed signals and outputs them to the user host. The direct output of the instrument is the main parameters such as concentration, speed, instantaneous flow, and total flow. The standard configuration is two-way output. Figure 2 shows the principle of capacitive solid mass flow measurement.
1.1.2 Application Range Application material range: Solid materials conveyed by dense phase, mainly coal powder.
The solid gas mass ratio (hereinafter referred to as the solid-gas ratio) is not less than 5:1, and on this basis, the accuracy of other conditions of use can reach 0.5% to 1%, and the universal accuracy of foreign users is 1% to 2%. The solid-gas ratio is between 4 and 5, the precision is reduced, and it is possible to reach 4% or even 8%; the solid-gas ratio is between 3 and 4 and the accuracy is further reduced; the solid-gas ratio is less than 3, and it is basically difficult to meet the measurement requirements.
Application pressure / temperature range: 12MPa/150 °C (optional 200 °C, special);
Applied hazardous situations: Suitable for Class I, Division1, GroupsA, B, C, D;
1.1.3 Application The main users of capacitive solid mass flow measurement technology are located in the coal chemical and steel industries. Foreign coal gasification is a typical dense phase transportation. The vast majority use non-nuclear measurement methods. That is, the solid mass flowmeter uses DC13 (concentration meter) + DK13 (velocity meter) to directly measure the coal powder mass flow. Shell is adopted abroad. The non-nuclear measurement method will also be used in the dense phase transportation process; the domestic pilot plant of the coal water slurry gasification and coal chemical national engineering research center ordered eight mass flow meters in 2004 and is still in the pilot plant and the East China University of Science and Technology. Room devices are used [2]. A capacitive solid mass flowmeter has been purchased on the domestic shell device of Yunnan Dawei and Sinopec Anqing, and it has not yet been put into operation. The application of the iron and steel industry is mainly the measurement and control of the quality of blast furnace coal injection in the steelmaking of steel mills. The domestic customers include mainly Shanghai Baosteel, Chongqing Iron and Steel Corporation, and Shagang.
At present, the main users of SWR are in space furnaces, including Henan Xiangyang Longyu Chemical Co., Ltd. and Anhui Linquan Chemical Co., Ltd. Two sets of US thermoelectric flow meters and one set of SWR flowmeters were simultaneously measured on each pulverized coal pipeline of the Fuyang Longyu Chemical Aerospace Furnace Project in Henan Province [3]. While satisfying the process requirements, they also verified the same Under the working conditions, the accuracy and reliability of the flow meter of the two manufacturers in the measurement of pulverized coal. Anhui Linquan used two sets of SWR flowmeters on each pulverized coal pipeline of the space furnace installation.
1.2 Nuclear Radiation Measurement Techniques The use of nuclear densitometers and speedometers to measure the quality of pulverized coal was developed and successfully applied to shell coal gasification technology by Ramsay of the United States in the 1990s. Later Bertohod company also began to set foot in similar fields.
1.2.1 Measurement Principles Nuclear radiation densitometers are also known as nuclear density meters, gamma densitometers, etc. The measurement principle is to measure the density using the energy attenuation method. The radioactive source (137Cs or 60Co) of the nuclear density meter is placed in a lead tank and installed on one side of the pipeline to be measured. The detector of the nuclear density meter is installed on the other side of the pipeline to be measured (symmetrical). The radiation source emits The gamma ray passes through the wall of the vessel under test and the medium reaches the detector. When the density of the medium in the tube changes, the energy of the ray received by the gamma densitometer detector also changes. The nuclear density meter converts the detected change in energy of the ray energy into the physical quantity required by the user—density [2]. With this technology, nuclear radiation densitometers can perform high-precision density measurements and quickly reflect changes in measured density. The densitometer measures the concentration and then outputs the measured value to the user host. The speedometer is used to measure the speed and output the speed signal to the master control system. The quality calculation is completed by the user's main system.
Thermo Fisher DensityPRO nuclear radiation mass flowmeter, densitometer includes two main parts: First, radioactive sources and lead tank; Second, integrated transmitter / detector. The radioactive source used in the densitometer generally uses a sealed radioactive source of 137Cs and 60Co in special cases. The PRO Core Density Meter basic measurement provides an independent loop-powered 4-20 mA output. The output can be set to 8 independent data or range channels. The unit can be selected by the user, including density, solid mass percentage, BRIX°, API°, and so on.
DensityPRO nuclear density meter has the advantages of high measurement accuracy, fast response speed and unique non-contact measurement method of nuclear densitometer. It meets the requirements for on-line medium density measurement of pulverized coal gasification and is widely used on domestic Shell devices. Germany Berto company uses radioactive density meter + electrostatic speed meter + calculation and compensation for measurement. The speedometer is electrostatic induction type. The principle is that during the pneumatic conveying of pulverized coal, the particles collide with each other and rub against each other to generate static electricity. After the velocity timing causes the fluctuation of the electrostatic field, a voltage signal is induced, and some adjacent pulverized coal particles are successively After the speedometer, a voltage waveform is induced. According to the time difference of the same signal received by two electrodes at a certain distance inside the speedometer, the flow rate of the pulverized coal is calculated. The main factors affecting the speed of Burton are coal particle size, moisture content, temperature, etc. [4].
1.2.2 Application Range Application material range: All solid materials transported in dilute phase or dense phase include pulverized coal, and the solid-gas ratio is not less than 5:1 in the conveying state, meeting other conditions of use, with an accuracy of 0.5% to 1%. The general accuracy of foreign users is 1% to 2%; when the solid-gas ratio is less than 4:1, the density measurement is the main control basis.
Application pressure / temperature range: 12MPa/150 °C (optional 200 °C, special);
Applied hazardous situations: Suitable for Class I, Division1, GroupsA, B, C, D;
1.2.3 Application Status The Thermo Fisher Scientific nuclear radiation mass flowmeter is mainly used in domestic Shell devices, such as Dalian Dahua Group, Zhongyuan Dahua Group, Sinopec Anqing Company, Sinopec Liuzhou Chemical Co., Ltd., Hubei Shuanghua Chemical Fertilizer Plant, etc. There are applications.
Germany Berto's nuclear radiation mass flowmeter is mainly used in Shell devices, such as Yueyang Sinopec Shell Coal Gasification Co., Ltd., Sinopec Hubei Branch, Yunnan Zhanhua Co., Ltd., China Shenhua Coal-to-Liquid Oil Co., Ltd., Shenhua Ning Coal, Henan Kaixiang Chemical Co., Ltd., Henan Longyu Coal Chemical Co., Ltd. and other units.
1.3 Microwave solids flow measurement 1.3.1 Measurement principle Microwave solids flow meter is suitable for the measurement of solid material flow in metal pipes. Using the microwave energy field and the reflection and Doppler properties of the solid particles on the microwaves, a measurement field is created through the special coupling of the electromagnetic field between the sensor and the pipe. The sensor sends a low-energy microwave signal to the solid particles of the metal conveying pipe. The signal is reflected by the solid and then received by the sensor. The frequency and amplitude of these signals are processed and utilized by the central processing unit. The density of the material is measured by moving the microwave reflection energy of the material, which is equivalent to a microwave counter, which records the number of particles of the material flowing in a unit time and measures the flow of the material. Due to the specific frequency, only the amount of particles that can flow can be measured, and the amount of deposited particles is not measured. The calibration of the sensor is performed after the installation is completed. Simply press the key and enter the reference quantity [5]. Figure 3 shows the measurement principle.
1.3.2 System Configuration A complete microwave solids measurement system consists of sensors and mounting bases, a central processing unit FME, and a C-Box junction box (connecting sensors and a central processing unit) [5]. Figure 4 shows the system composition.
1.3.3 Application The microwave solids measurement system is mainly used in the large-scale coal-fired units in the power plant boiler system and the blast furnace pulverized coal in the steelmaking plant. Dust-like fuel is sent to the boiler for secondary fuel. A solid flow detector is used to measure the flow rate on each feed pipe to optimize the combustion. The application of blast furnace pulverized coal is similar.
At present, more applications for the French EDIT solid flowmeter. The flow meter uses a microwave-based measuring principle with an accuracy of 1% to 2%, and the measurement accuracy indicated on the product sample is 1%. The flowmeter has no application performance in the powder coal gas chemical industry. All domestic performances are obtained on the power plant and steelmaking plant blast furnace pulverized coal pipelines.
2 Differences between capacitive and nuclear radiation measurement methods 2.1 Concentration measurement techniques Different nuclear measurement techniques use a nuclear density meter to measure the concentration of pulverized coal, using DK13 to measure speed. Non-nuclear technologies use a capacitive densitometer to measure the concentration and velocity measurement speed. Table 1 compares the advantages and disadvantages of the two.
2.2 Tasks undertaken by equipment Different nuclear radiation measurement technologies do not directly provide calculation and display of mass flow, but the user's main system calculates according to the model of the process provider that the instrument only provides concentration and velocity measurement values; non-nuclear measurement technology directly calculates the instantaneous Flow, cumulative flow, concentration, speed, and if necessary, direct control of the associated feed equipment (PID control).
2.3 Different measurement accuracy uses Thermo Fisher's nuclear densitometer + speed meter measurement method (nuclear measurement technology), the nuclear density meter is used to measure the concentration of the nominal accuracy level is 0.2%, the speed meter is generally used capacitive type Measuring principle, accuracy level 1%.
Using Thermo Fisher Scientific's capacitive solids mass flowmeters (non-nuclear measurement technology density), models Granucor DC/13, DK13, DC13 measurement error in dilute phase delivery conditions is large (5% or greater), ultra dense phase When pulverized coal occurs due to plunger, stagnation and backflow, the fluidity deviates from the ideal situation, and the DC13 velocity measurement value will be greatly deviated, especially when the DC13 is installed in the horizontal pipeline or even the pipeline where the material flows from bottom to top. 6% or more; but Thermo Fisher has updated the DC13 hardware and the corresponding measurement software (based on the principle of cross-correlation).
2.4 Calibration method The accuracy of different nuclear radiation measurement technology measurement needs to be adjusted by measured data. It needs to be calibrated with the carrier gas in the transport mode first, and then the coal powder is calibrated by circulating transport.
The non-nuclear measurement technology of Thermo Fisher Scientific (United States Thermoelectric) is based on the experience of pilot test of coal-water slurry gasification and national engineering research center of coal chemical industry. It does not need to calibrate the carrier gas alone, but calibrates it under the conveying conditions. . After the calibration is completed, it can be simply verified before chemical feeding.
3 Research on the use of capacitive solid mass flowmeters As early as 2004, the National Engineering Research Center for Coal Water Slurry Gasification and Coal Chemical Engineering and East China University of Science and Technology undertook the key task of the National “Tenth Five-Year Plan†scientific and technological research: “Pulverized Coal Pressure Gasification Preparation and Synthesis At the time of gas research and development, 8 sets of US Thermoelectric (formerly Ramsay) solid mass flow meters Model 2109 were purchased for the transportation and measurement of pulverized coal. The use process shows that the measurement of the mass flow meter has reached a certain accuracy, and can fully meet the requirements of industrial applications; the measurement accuracy of the flow meter is not only related to the hardware and software settings of the instrument itself, but also the flow pattern of coal powder in the pipeline. Have a close relationship. East China University of Science and Technology and National Engineering Research Center for Coal-Water Slurry Gasification and Coal Chemical Industry have developed a solid-to-gas ratio, stability, material flow, and moisture content for the DC13 and DK13 combined mass flow measurement system for dense-phase pneumatic conveying of pulverized coal. Study of other influencing factors [5]. The results show that the overall measurement deviation under the dense-phase stable delivery condition is within 10%, and the optimization condition can reach within 5%. It has been successfully applied to the pulverized coal gasification pilot plant, and it fully meets the process requirements for the gasification of the pulverized-coal gas flow bed.
In the “Eleventh Five-Year†863 project “Application of high-ash-melting-point gas-flow bed pressure gasificationâ€, the National Engineering Research Center for Coal-Water-Slurry Gasification and Coal Chemicals purchased a SENS Densfow capacitive flowmeter in 2009. , and East China University of Science and Technology to jointly develop industrial-scale coal powder transportation research. The measurement results show that the measurement error of the solid mass flowmeter can be controlled within 7%, which is equivalent to the performance of the combination of the Thermo Fisher DC13 and DK13, and meets the industrial operation requirements.
4 Conclusions and Recommendations (1) From the standpoint of using performance, the radiometers of Thermo Fisher Scientific and Bertog, Germany, are widely used in the domestic coal chemical industry. The capacitive type is mainly used in the steel industry and coal chemical industry. The company is mainly used in the trial of Yankuang and the Dawei plant of Yunnan; SWR is mainly used on domestic space furnaces.
(2) U.S. thermoelectric capacitive flowmeters and German SWR flowmeters have the same source, measurement principles are similar, and there is no essential difference in technology. Industrial application practice in recent years has shown that the measurement of the pulverized coal flow rate in a pulverized coal pressure gasification plant is effective.
(3) Because the dense phase transportation of pulverized coal is a gas-solid two-phase flow, the measurement and control are extremely complicated. Due to the limitation of the measurement principle, the two kinds of flowmeters have limitations in the measurement of the concentration and change in the pulverized coal flow pattern. When there is a large error in the concentration measurement.
(4) For the first time in the application of pulverized coal pressure gasification, it is recommended to set at least one nuclear density meter on the pulverized coal pipeline of each gasifier to accurately measure the pulverized coal flow during the initial driving period and accumulate operating experience.
(5) The above-mentioned instruments have relatively strict requirements on the process, and the design and construction should be carried out in strict accordance with the requirements of the instrument. During the operation, the requirements of the instrument should be met as far as possible from the process.
references:
[1] Ni Weidou, Li Zheng. Polygeneration energy system with coal gasification as the core [J]. Coal Chemical Industry, 2003, 104 (1): 3.
[2]Guo Yunzhou, Guo Xiaolei, Guo Weiguo. Application of Solid Mass Flowmeter in Dense Phase Pneumatic Conveying[J]. Automation Instrumentation, 2007,28(6):17-18.
[3] Xiao Ling, Liu Lianjing. Application of German SWR flowmeter in pulverized coal gasification equipment——space furnace[J].Control and Instruments in Chemical Industry,2010,37(5):112-113.
[4] Jiang Huadong. Application of microwave solid flowmeter in the measurement of pulverized coal[J]. Petrochemical Automation, 2009(3):54-55.(end)
Keywords: Capacitive solid mass flowmeter Gas-solid two-phase flow measurement Nuclear radiation powder coal gasification is one of the latest technologies in clean coal technology. The pulverized coal gasification process is characterized by Shell, GSP, aerospace furnaces, etc., which are characterized by continuous feed of pulverized coal and pressurized continuous operation. This type of process has the characteristics of pure oxygenation, dense phase pneumatic conveying of powdered coal, and liquid slagging. It has high efficiency of cold gas, wide adaptability of coal, high carbon conversion rate, high degree of automation, large production capacity, and good gas quality. Can meet environmental protection requirements, with strong technical advantages [1].
The flow rate of pulverized coal in pulverized coal gasification process is an important parameter concerning the stability and safe operation of the system. The pulverized coal mass flow meter is the key instrument. At present, the measurement of dry-powder dense-phase transportation can be roughly divided into two types: capacitive and radiant, mainly Thermo Fisher (formerly American Thermal Power Company, mainly found in Shell) and Swell (SWR, Germany). ), Germany Berto and France EDITFLOW and so on.
1 Solid mass flow measurement technology and products 1.1 Capacitance The measurement technology is widely used, representative of Thermo Fisher and the German SWR. In essence, SWR's solids flowmeters and Thermo Fisher's capacitive solids mass flowmeters are based on the same technology and are similar in their measurement of pressure, concentration, sensitivity, and accuracy.
1.1.1 Measurement Principle Capacitance plates are installed outside the flow pipe. When the gas-solid ratio in the pipe changes, the dielectric constant changes accordingly, causing a change in capacitance. Measure the capacitance between the plates, and then convert the digital signal to obtain the phase concentration in the pipe. Figure 1 shows the capacitor plate system.
Figure 1 Capacitor plate system
The speed sensor consists of two capacitive sensors. The distance between the two sensors is 8mm. The solid particles pass through two sensors in sequence. Ideally, the flow pattern of the solid material does not change after a short distance. The two sensors can capture the same material flow pattern signal. The solid particle velocity can be calculated from the time difference between the signals [2].
According to the ratio of material quality to capacitance, the concentration of the material is measured by measuring the change in capacitance, and the speed of the material is measured by the cross-correlation model (the measurement basis is still the change in capacitance). The mass mass flow calculation formula is:
Q=CAVK
In the formula, Q is the mass flow rate, kg/s; C is the solid mass concentration, kg/m3; A is the cross-sectional area of ​​the sensor, m2; V is the average solid flow rate, m/s; K is the correction factor, no dimension.
Thermo Fisher Scientific's solid mass flow meter consists of the concentration meter DC13, speedometer DK13, secondary meter MT2109 or MT2107 (optional when PID regulation is required).
The instrument processes the concentration and speed signals and outputs them to the user host. The direct output of the instrument is the main parameters such as concentration, speed, instantaneous flow, and total flow. The standard configuration is two-way output. Figure 2 shows the principle of capacitive solid mass flow measurement.
Figure 2 Principle of Capacitive Solid Mass Flow Measurement
SWR's solid flowmeter integrates a speedometer and a density meter into a single module. The length is short (about 400mm), and the secondary instrument has less relative functionality, so it is small in size. 1.1.2 Application Range Application material range: Solid materials conveyed by dense phase, mainly coal powder.
The solid gas mass ratio (hereinafter referred to as the solid-gas ratio) is not less than 5:1, and on this basis, the accuracy of other conditions of use can reach 0.5% to 1%, and the universal accuracy of foreign users is 1% to 2%. The solid-gas ratio is between 4 and 5, the precision is reduced, and it is possible to reach 4% or even 8%; the solid-gas ratio is between 3 and 4 and the accuracy is further reduced; the solid-gas ratio is less than 3, and it is basically difficult to meet the measurement requirements.
Application pressure / temperature range: 12MPa/150 °C (optional 200 °C, special);
Applied hazardous situations: Suitable for Class I, Division1, GroupsA, B, C, D;
1.1.3 Application The main users of capacitive solid mass flow measurement technology are located in the coal chemical and steel industries. Foreign coal gasification is a typical dense phase transportation. The vast majority use non-nuclear measurement methods. That is, the solid mass flowmeter uses DC13 (concentration meter) + DK13 (velocity meter) to directly measure the coal powder mass flow. Shell is adopted abroad. The non-nuclear measurement method will also be used in the dense phase transportation process; the domestic pilot plant of the coal water slurry gasification and coal chemical national engineering research center ordered eight mass flow meters in 2004 and is still in the pilot plant and the East China University of Science and Technology. Room devices are used [2]. A capacitive solid mass flowmeter has been purchased on the domestic shell device of Yunnan Dawei and Sinopec Anqing, and it has not yet been put into operation. The application of the iron and steel industry is mainly the measurement and control of the quality of blast furnace coal injection in the steelmaking of steel mills. The domestic customers include mainly Shanghai Baosteel, Chongqing Iron and Steel Corporation, and Shagang.
At present, the main users of SWR are in space furnaces, including Henan Xiangyang Longyu Chemical Co., Ltd. and Anhui Linquan Chemical Co., Ltd. Two sets of US thermoelectric flow meters and one set of SWR flowmeters were simultaneously measured on each pulverized coal pipeline of the Fuyang Longyu Chemical Aerospace Furnace Project in Henan Province [3]. While satisfying the process requirements, they also verified the same Under the working conditions, the accuracy and reliability of the flow meter of the two manufacturers in the measurement of pulverized coal. Anhui Linquan used two sets of SWR flowmeters on each pulverized coal pipeline of the space furnace installation.
1.2 Nuclear Radiation Measurement Techniques The use of nuclear densitometers and speedometers to measure the quality of pulverized coal was developed and successfully applied to shell coal gasification technology by Ramsay of the United States in the 1990s. Later Bertohod company also began to set foot in similar fields.
1.2.1 Measurement Principles Nuclear radiation densitometers are also known as nuclear density meters, gamma densitometers, etc. The measurement principle is to measure the density using the energy attenuation method. The radioactive source (137Cs or 60Co) of the nuclear density meter is placed in a lead tank and installed on one side of the pipeline to be measured. The detector of the nuclear density meter is installed on the other side of the pipeline to be measured (symmetrical). The radiation source emits The gamma ray passes through the wall of the vessel under test and the medium reaches the detector. When the density of the medium in the tube changes, the energy of the ray received by the gamma densitometer detector also changes. The nuclear density meter converts the detected change in energy of the ray energy into the physical quantity required by the user—density [2]. With this technology, nuclear radiation densitometers can perform high-precision density measurements and quickly reflect changes in measured density. The densitometer measures the concentration and then outputs the measured value to the user host. The speedometer is used to measure the speed and output the speed signal to the master control system. The quality calculation is completed by the user's main system.
Thermo Fisher DensityPRO nuclear radiation mass flowmeter, densitometer includes two main parts: First, radioactive sources and lead tank; Second, integrated transmitter / detector. The radioactive source used in the densitometer generally uses a sealed radioactive source of 137Cs and 60Co in special cases. The PRO Core Density Meter basic measurement provides an independent loop-powered 4-20 mA output. The output can be set to 8 independent data or range channels. The unit can be selected by the user, including density, solid mass percentage, BRIX°, API°, and so on.
DensityPRO nuclear density meter has the advantages of high measurement accuracy, fast response speed and unique non-contact measurement method of nuclear densitometer. It meets the requirements for on-line medium density measurement of pulverized coal gasification and is widely used on domestic Shell devices. Germany Berto company uses radioactive density meter + electrostatic speed meter + calculation and compensation for measurement. The speedometer is electrostatic induction type. The principle is that during the pneumatic conveying of pulverized coal, the particles collide with each other and rub against each other to generate static electricity. After the velocity timing causes the fluctuation of the electrostatic field, a voltage signal is induced, and some adjacent pulverized coal particles are successively After the speedometer, a voltage waveform is induced. According to the time difference of the same signal received by two electrodes at a certain distance inside the speedometer, the flow rate of the pulverized coal is calculated. The main factors affecting the speed of Burton are coal particle size, moisture content, temperature, etc. [4].
1.2.2 Application Range Application material range: All solid materials transported in dilute phase or dense phase include pulverized coal, and the solid-gas ratio is not less than 5:1 in the conveying state, meeting other conditions of use, with an accuracy of 0.5% to 1%. The general accuracy of foreign users is 1% to 2%; when the solid-gas ratio is less than 4:1, the density measurement is the main control basis.
Application pressure / temperature range: 12MPa/150 °C (optional 200 °C, special);
Applied hazardous situations: Suitable for Class I, Division1, GroupsA, B, C, D;
1.2.3 Application Status The Thermo Fisher Scientific nuclear radiation mass flowmeter is mainly used in domestic Shell devices, such as Dalian Dahua Group, Zhongyuan Dahua Group, Sinopec Anqing Company, Sinopec Liuzhou Chemical Co., Ltd., Hubei Shuanghua Chemical Fertilizer Plant, etc. There are applications.
Germany Berto's nuclear radiation mass flowmeter is mainly used in Shell devices, such as Yueyang Sinopec Shell Coal Gasification Co., Ltd., Sinopec Hubei Branch, Yunnan Zhanhua Co., Ltd., China Shenhua Coal-to-Liquid Oil Co., Ltd., Shenhua Ning Coal, Henan Kaixiang Chemical Co., Ltd., Henan Longyu Coal Chemical Co., Ltd. and other units.
1.3 Microwave solids flow measurement 1.3.1 Measurement principle Microwave solids flow meter is suitable for the measurement of solid material flow in metal pipes. Using the microwave energy field and the reflection and Doppler properties of the solid particles on the microwaves, a measurement field is created through the special coupling of the electromagnetic field between the sensor and the pipe. The sensor sends a low-energy microwave signal to the solid particles of the metal conveying pipe. The signal is reflected by the solid and then received by the sensor. The frequency and amplitude of these signals are processed and utilized by the central processing unit. The density of the material is measured by moving the microwave reflection energy of the material, which is equivalent to a microwave counter, which records the number of particles of the material flowing in a unit time and measures the flow of the material. Due to the specific frequency, only the amount of particles that can flow can be measured, and the amount of deposited particles is not measured. The calibration of the sensor is performed after the installation is completed. Simply press the key and enter the reference quantity [5]. Figure 3 shows the measurement principle.
Fig. 3 Measurement principle of microwave solid flow meter
1.3.2 System Configuration A complete microwave solids measurement system consists of sensors and mounting bases, a central processing unit FME, and a C-Box junction box (connecting sensors and a central processing unit) [5]. Figure 4 shows the system composition.
Fig. 4 Composition of microwave solid measurement system
1.3.3 Application The microwave solids measurement system is mainly used in the large-scale coal-fired units in the power plant boiler system and the blast furnace pulverized coal in the steelmaking plant. Dust-like fuel is sent to the boiler for secondary fuel. A solid flow detector is used to measure the flow rate on each feed pipe to optimize the combustion. The application of blast furnace pulverized coal is similar.
At present, more applications for the French EDIT solid flowmeter. The flow meter uses a microwave-based measuring principle with an accuracy of 1% to 2%, and the measurement accuracy indicated on the product sample is 1%. The flowmeter has no application performance in the powder coal gas chemical industry. All domestic performances are obtained on the power plant and steelmaking plant blast furnace pulverized coal pipelines.
2 Differences between capacitive and nuclear radiation measurement methods 2.1 Concentration measurement techniques Different nuclear measurement techniques use a nuclear density meter to measure the concentration of pulverized coal, using DK13 to measure speed. Non-nuclear technologies use a capacitive densitometer to measure the concentration and velocity measurement speed. Table 1 compares the advantages and disadvantages of the two.
Table 1 Comparison of nuclear measurement technology and non-nuclear measurement technology
2.3 Different measurement accuracy uses Thermo Fisher's nuclear densitometer + speed meter measurement method (nuclear measurement technology), the nuclear density meter is used to measure the concentration of the nominal accuracy level is 0.2%, the speed meter is generally used capacitive type Measuring principle, accuracy level 1%.
Using Thermo Fisher Scientific's capacitive solids mass flowmeters (non-nuclear measurement technology density), models Granucor DC/13, DK13, DC13 measurement error in dilute phase delivery conditions is large (5% or greater), ultra dense phase When pulverized coal occurs due to plunger, stagnation and backflow, the fluidity deviates from the ideal situation, and the DC13 velocity measurement value will be greatly deviated, especially when the DC13 is installed in the horizontal pipeline or even the pipeline where the material flows from bottom to top. 6% or more; but Thermo Fisher has updated the DC13 hardware and the corresponding measurement software (based on the principle of cross-correlation).
2.4 Calibration method The accuracy of different nuclear radiation measurement technology measurement needs to be adjusted by measured data. It needs to be calibrated with the carrier gas in the transport mode first, and then the coal powder is calibrated by circulating transport.
The non-nuclear measurement technology of Thermo Fisher Scientific (United States Thermoelectric) is based on the experience of pilot test of coal-water slurry gasification and national engineering research center of coal chemical industry. It does not need to calibrate the carrier gas alone, but calibrates it under the conveying conditions. . After the calibration is completed, it can be simply verified before chemical feeding.
3 Research on the use of capacitive solid mass flowmeters As early as 2004, the National Engineering Research Center for Coal Water Slurry Gasification and Coal Chemical Engineering and East China University of Science and Technology undertook the key task of the National “Tenth Five-Year Plan†scientific and technological research: “Pulverized Coal Pressure Gasification Preparation and Synthesis At the time of gas research and development, 8 sets of US Thermoelectric (formerly Ramsay) solid mass flow meters Model 2109 were purchased for the transportation and measurement of pulverized coal. The use process shows that the measurement of the mass flow meter has reached a certain accuracy, and can fully meet the requirements of industrial applications; the measurement accuracy of the flow meter is not only related to the hardware and software settings of the instrument itself, but also the flow pattern of coal powder in the pipeline. Have a close relationship. East China University of Science and Technology and National Engineering Research Center for Coal-Water Slurry Gasification and Coal Chemical Industry have developed a solid-to-gas ratio, stability, material flow, and moisture content for the DC13 and DK13 combined mass flow measurement system for dense-phase pneumatic conveying of pulverized coal. Study of other influencing factors [5]. The results show that the overall measurement deviation under the dense-phase stable delivery condition is within 10%, and the optimization condition can reach within 5%. It has been successfully applied to the pulverized coal gasification pilot plant, and it fully meets the process requirements for the gasification of the pulverized-coal gas flow bed.
In the “Eleventh Five-Year†863 project “Application of high-ash-melting-point gas-flow bed pressure gasificationâ€, the National Engineering Research Center for Coal-Water-Slurry Gasification and Coal Chemicals purchased a SENS Densfow capacitive flowmeter in 2009. , and East China University of Science and Technology to jointly develop industrial-scale coal powder transportation research. The measurement results show that the measurement error of the solid mass flowmeter can be controlled within 7%, which is equivalent to the performance of the combination of the Thermo Fisher DC13 and DK13, and meets the industrial operation requirements.
4 Conclusions and Recommendations (1) From the standpoint of using performance, the radiometers of Thermo Fisher Scientific and Bertog, Germany, are widely used in the domestic coal chemical industry. The capacitive type is mainly used in the steel industry and coal chemical industry. The company is mainly used in the trial of Yankuang and the Dawei plant of Yunnan; SWR is mainly used on domestic space furnaces.
(2) U.S. thermoelectric capacitive flowmeters and German SWR flowmeters have the same source, measurement principles are similar, and there is no essential difference in technology. Industrial application practice in recent years has shown that the measurement of the pulverized coal flow rate in a pulverized coal pressure gasification plant is effective.
(3) Because the dense phase transportation of pulverized coal is a gas-solid two-phase flow, the measurement and control are extremely complicated. Due to the limitation of the measurement principle, the two kinds of flowmeters have limitations in the measurement of the concentration and change in the pulverized coal flow pattern. When there is a large error in the concentration measurement.
(4) For the first time in the application of pulverized coal pressure gasification, it is recommended to set at least one nuclear density meter on the pulverized coal pipeline of each gasifier to accurately measure the pulverized coal flow during the initial driving period and accumulate operating experience.
(5) The above-mentioned instruments have relatively strict requirements on the process, and the design and construction should be carried out in strict accordance with the requirements of the instrument. During the operation, the requirements of the instrument should be met as far as possible from the process.
references:
[1] Ni Weidou, Li Zheng. Polygeneration energy system with coal gasification as the core [J]. Coal Chemical Industry, 2003, 104 (1): 3.
[2]Guo Yunzhou, Guo Xiaolei, Guo Weiguo. Application of Solid Mass Flowmeter in Dense Phase Pneumatic Conveying[J]. Automation Instrumentation, 2007,28(6):17-18.
[3] Xiao Ling, Liu Lianjing. Application of German SWR flowmeter in pulverized coal gasification equipment——space furnace[J].Control and Instruments in Chemical Industry,2010,37(5):112-113.
[4] Jiang Huadong. Application of microwave solid flowmeter in the measurement of pulverized coal[J]. Petrochemical Automation, 2009(3):54-55.(end)
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