Gas Volume Flow Research Articles

Study of the structure of gas flow іn a cyclone wіth іntermedіate dust removal

The works in which designs of the dust collectors, which are often used in the industry, are analyzed. It is shown that the efficiency of dust collectors largely depends on the structure of the gas flow in the apparatus. Based on the analysis of the current cyclone devices, a picture of the separation process is obtained, and the factors that negatively affect the operation of dust collectors are identified. It is established that forecasting the work of dust collecting devices in certain conditions is most effective to perform methods of numerical modeling and simulation of the separation process, which are widely used for the research of devices of this type. Using the methods of numerical simulation, the study of the cyclone with intermediate dust removal was carried out. In this cyclone, the change in the radius of the apparatus of the tangential, radial, and axial velocity components is investigated. In the course of the research, it is established that in the separation space the tangential component of velocity increases from 18–20 m/s in the upper part of the device to 22–25 m/s in the area of the lower end of the exhaust pipe, the radial component of velocity takes values from 0 to 2 m/s, and the axial component of the speed has a maximum value of 10–15 m/s. In the conical part of the apparatus the tangential component of velocity decreases from 27 m/s in the upper planes of the conical part of the apparatus to 10 m / s near the dust unloading pipe, the radial component of speed has centripetal character, the axial component of speed decreases as the gas flow to the dust unloading pipe decreases. It has been established that in the cylindrical part of the apparatus about 60 % of the gas flow volume is transferred from the downstream to the upstream by a secondary vortex, and in the conical part, about 40 % of the gas volume is transferred from the downstream to the upstream. It is shown that large values of the tangential component of velocity in the separation zone contribute to the ingress of dust particles into the annular space behind the dust unloading holes, and small values of the tangential component of velocity, axial and radial in the annular space behind the dust unloading holes has a positive effect on the operation of the dust collector.

Measurement Standards of Ukraine for Gas Volume Flow Rate at Pressures of 1 MPa to 5 MPa

The characteristics of the primary measurement standards of the volume gas flow rate at high pressure developed in various countries are considered. A hierarchical scheme for gas flow measuring instruments and a corresponding metrological traceability chain are presented. Described is a PVTt method, on which the primary standards of gas flow rate used in the USA, France, Japan, and Taiwan are based. The need to create in Ukraine primary measurement standards of gas flow rate at high pressure covering different parts of the total flow rate interval from 0,3 m3/h to 1800 m3/h at a pressure of 1 MPa to 5 MPa is substantiated. Metrological traceability of gas flow measurements is realized through a sequence of critical flow Venturi nozzles, which play a role of the reference flow rate material measures. The standards might be used to calibrate the primary reference Venturi nozzles of the most common 0,1 mm to 8 mm diameters. The characteristics and parameters of the standards are determined. By their metrological and technical characteristics, the standards will correspond to the state-of-the-art level. According to the programme of developing the measurement-standard facilities in Ukraine, in 2019 the primary standard PVTt-65 was created and work had started on the development of the primary standard PVTt-1800 and the working standard PE-5400. A detailed study of the metrological characteristics of the measurement standards will be the topic of further work.

Mechanisms of gas temperature variation of the atmospheric microwave plasma torch

The gas temperature is a key parameter that affects the process of microwave plasma chemistry in industrial applications. Based on the molecular emission spectrometry of the A2Σ+→X2Πr electronic system of OH radicals, the gas temperature of the atmospheric air microwave plasma core at different absorbed microwave power levels, gas flow rates, gas humidities, and volume fractions of CO2 in air was analyzed. In the experiment, the absorbed microwave power, gas flow rate, gas humidity, and volume ratio of CO2 in air was varied from 560 to 1750 W, 10 to 24 l min−1, 30% to 95%, and 0% to 40%, respectively. Moreover, the axial gas temperature distribution of the plasma torch was measured. The experimental results showed that (i) the plasma gas temperature mainly ranged from 4000 to 7000 K, (ii) the plasma gas temperature rose with increasing absorbed microwave power but was hardly affected by the feeding gas flow rate, (iii) the plasma gas temperature decreased by ∼400 K for every 20% increase in the fraction of CO2 in air and decreased with increasing gas humidity, and (iv) the plasma torch gas temperature decreased along the axial direction. Due to the lack of a prevailing microwave discharge theory, an in-depth analysis of the mechanisms of gas temperature variation was performed based on the heat balance equation.

CONTROLLED LIFTING THE BELL OF THE STATE PRIMARY GAS VOLUME AND VOLUME FLOW RATE STANDARD

The article describes the implemented system of pneumatic lifting of the bell of the state primary standard gas volume and volume flow rate units. The system is composed of unified elements of industrial air preparation. There are elements for air purification in front of the compressor, dehumidifier, refrigerator dryer. With the use of a pneumatic system, the bell can be filled with prepared air with different values of excess pressure. The system is installed as a backup to the current to increase security. Pneumatic lifting of the bell allows you to connect a set of cylinders with pure inert gases or mixtures thereof to determine the impact on the gas meters metrological characteristics.

An in-situ calorimeter for coal powder: A numerical investigation

Timely monitoring of the calorific value of coal is beneficial to combustion regulation during the operation of coal-fired power plants. An in-situ measurement system applied to power plants was proposed. The related model was described in detail and validated through bomb calorimetry. The influences of multiple model parameters with different thermometer and flowmeter accuracy on measurement time and uncertainty have been analyzed. Measurement properties of the bomb calorimeter and this improved calorimeter were compared at different conditions. The results reveal the increases in the gas volume flow rate and the water mass flow rate have a positive effect on measurement time while coal mass and the mass ratio of water in two cylinders show a negative effect. Relative standard uncertainties are reduced to some extent with all of these factors. It is evidenced the proposed calorimeter has the potential for fuel calorific value monitor for power plant operation optimization.

Effect of the Gas Volume Fraction on the Pressure Load of the Multiphase Pump Blade

The gas volume fraction (GVF) often changes from time to time in a multiphase pump, causing the power capability of the pump to be increasingly affected. In the purpose of revealing the pressure load characteristics of the multiphase pump impeller blade with the gas-liquid two-phase case, firstly, a numerical simulation which uses the SST k-ω turbulence model is verified with an experiment. Then, the computational fluid dynamics (CFD) software is employed to investigate the variation characteristics of static pressure and pressure load of the multiphase pump impeller blade under the diverse inlet gas volume fractions (IGVFs) and flow rates. The results show that the effect of IGVF on the head and hydraulic efficiency at a small flow rate is obviously less than that at design and large flow rates. The static pressure on the blade pressure side (PS) is scarcely affected by the IGVF. However, the IGVF has an evident effect on the static pressure on the impeller blade suction side (SS). Moreover, the pump power capability is descended by degrees as the IGVF increases, and it is also descended with the increase of the flow rate at the impeller inlet. Simultaneously, under the same IGVF, with the increase of the flow rate, the peak value of the pressure load begins to gradually move toward the outlet and its value from hub to shroud is increased. The research results have important theoretical significance for improving the power capability of the multiphase pump impeller.

Discharge stability analysis of top discharge blow tank in dense-phase pneumatic conveying system

Dense-phase pneumatic conveying is widely applied in large-scale entrained-bed gasification systems for feeding and conveying pulverized coal into the gasifiers. The discharge stability of blow tanks will affect the conveying process of powders in the conveying pipelines, and ultimately influence the long-term safe and stable operation of the gasifiers. In this paper, aiming at the problem of controllable discharge and conveying of powders in dense-phase pneumatic conveying systems, the research on the discharge analysis of a top discharge blow tank was carried out, which improves the understanding of top discharge blow tanks. Shannon entropy analysis and relative standard deviation analysis based on instantaneous solid mass flow rate signals were used as indicators for the discharge stability. The effects of operating conditions, powder external moisture content, and blow tank structural parameters on the discharge stability of a top discharge blow tank were investigated. The results indicate that for a given pneumatic conveying system, there exists an optimal supplementary gas volume flow rate corresponding to the most stable discharge process of the blow tank. With an increase in the external moisture content of pulverized coal, the discharge stability of the blow tank first increases and then decreases. As the riser diameter increases, the discharge process of the blow tank becomes unstable owing to the increase in the randomness of the conveying process.

On the performance of a centrifugal pump under bubble inflow: Effect of gas-liquid distribution in the impeller

Determining the characteristics of gas-liquid two-phase flow in centrifugal pumps is essential for a better understanding of pump performance. In this study, a visualization investigation was performed to determine the effect of the gas-liquid distribution in the impeller on the performance of a centrifugal pump with a closed impeller. Emphasis was placed on the influences of the inlet gas volume fraction (IGVF), flow rate, and rotational speed on the gas-liquid distribution in the impeller and, thus, on the surging characteristics of the pump. The correlation mechanism between the distribution of the gas-liquid phase in the impeller and the surging characteristics of the pump was revealed. Finally, several surging prediction models were examined. The results show that the gas-liquid two-phase distribution in the impeller has an immediate impact on the pressure increment and efficiency of the pump. The increase in IGVF directly induced pump surging by changing the flow pattern in the impeller. Surging occurred when the flow pattern changed from gas pocket flow to segregated flow. It was also found that pump surging could be eliminated by adjusting the flow rate and increasing the rotational speed, which changed the flow pattern inside the impeller. Compared with the experimental results, the critical IGVF obtained by the existing surging prediction model exhibits some deviation. The surging prediction model dedicated to the volute centrifugal pump requires further investigation. The results reported here can provide better insight into the performance of volute-type centrifugal pumps and provide a reference for developing corresponding surging prediction models.

Research on the Flow Characteristic in a Multi-Stage Multiphase Pump by Numerical Simulations

As a cost-effective option for subsea gas and oil fields development, multiphase pump has been widely used and plays an important role in promoting field production especially for those brownfields. The objective of this research is to study the variations of flow parameters at the inlet of each stage in a five-stage helico-axial pump under design conditions by using commercial CFD packages. The numerical results show that inlet volume flow rate, gas volume fraction (GVF) and flow angle of each stage both decreases from the first stage to the fifth stage because of the compression. The variations of these parameters along the flow direction are susceptible to the effect of rotational speed and initial gas volume fraction at inlet of the first stage. These inlet flow parameters from inlet to outlet of the five-stage pump just change little when the initial inlet GVF is lower than 10% or higher than 90%. While the variation is obvious when inlet GVF is from 20% to 80%. Based on numerical simulation results, the stage-by-stage design method is proposed and geometry parameters such as inlet impeller hub diameter and inlet angle of blade in the second stage are modified according to its inlet flow conditions. The comparison results between the modified pump and original pump show that pressure distribution at leading edge of impeller blades in each stage becomes uniform in the modified multistage pump. The inlet incident flow loss of each stage is diminished and internal flow conditions has been significantly improved. Thus, the pump’s boosting capacity is enhanced. These research results in this paper are instructive for the performance optimization of multistage pumps used in gas oil fields.

Effect of Shielding Gas Volume Flow on the Consistency of Microstructure and Tensile Properties of 316L Manufactured by Selective Laser Melting

In recent years, selective laser melting (SLM) has been widely used in aerospace, automobile, biomedicine and other fields. However, there still remain many challenges to obtain consistent parts at the different positions on the base plate, which could be harmful to the industrial mass-production. In SLM process, the process by-products that flow with the shielding gas may influence the microstructure and tensile properties of the parts placed on different positions of the base plate. In this study, the velocity field of the shielding gas with different shielding gas volume flows was simulated. The tensile properties of the samples fabricated with different shielding gas volume flow were experimentally studied. The results show that the shielding gas volume flow has a strong influence on the sample consistency, and proper increase in shielding gas volume flows can be beneficial to consistency and tensile strength.

Numerical study of the equivalent roughness effect on the low-flow centrifugal compressor impeller characteristics

The article presents the results of a numerical study of the effect of equivalent sandgrain roughness on the characteristics of a low-flow centrifugal compressor stage. Low-flow stages are widely used in high-pressure compressors as the last stages. These compressors are used for natural gas booster compressor stations, as well as in technological processes for the production of methanol, ammonia, high - pressure polyethylene, etc. The efficiency of the low-flow stages is lower than that of medium-and high-flow centrifugal compressors stages. Stages operate at high pressure and have low gas volume flow rates. For this reason they have narrow channels of the flow part, significant friction and leakage losses. The study was conducted in the Ansys CFX 19.2 software package. In the first part of the study, the low-flow stage numerical model is validated with the test results. Full-scale tests of the stage were carried out at the LPI-SPbPU earlie. In the second part of the study, impeller equivalent sand-grain roughness numerical study carried out. As a result, the characteristics of the stage were obtained at four different values of equivalent sand-grain roughness ks. The impeller losses were estimated. It is established that when the ks values increase, the polytropic head and efficiency values do not decrease equally over the entire characteristic. Characteristics are significantly reduced in areas of high expenditure and change slightly with minimal expenditure. The internal head coefficient varies slightly depending on ks.

A large-scale experimental study on CO2 capture utilizing slurry-based ab-adsorption approach

The increasing concentration of CO 2 in atmosphere is deemed the main reason of global warming. Therefore, efficiently capturing CO 2 from various sources with energy conservation is of great significance. Herein, a series of experiments were carried out to successfully test the slurry-based ab-adsorption method for continuously capturing CO 2 in the large-scale cycled separation unit with cost-effect taking into account the scale-up criteria. A bubble column (with height 4900 mm and inner diameter 376 mm) and a desorption tank (with volume 310 L) are the essential components of the separation unit. The novel slurry used in this study was formed with zeolitic imidazolate framework-8 and 2-methylimidazole-water solution. The influence of operation conditions was investigated systematically. The results show that increasing sorption pressure and slurry height level, decreasing gas volume flow and sorption temperature are beneficial for separation processes. The volume fraction of CO 2 in the feed gas was also studied. Although the scale-up effect had been observed and it was found that it exerted a negative effect on CO 2 capture, depending on experimental conditions, CO 2 removal efficiency could still reach 85%-95% and the maximum CO 2 loading in the recycled slurry could be up to 0.007 mol⋅L −1 ⋅kPa −1 . Furthermore, the slurry-based method could be operated well even under very moderate regeneration conditions (333 K and 0.05 MPa), which means that the novel approach shows greater energy conservation than traditional amine absorption methods.

The Traceability Improvement and Comparison of Bell Prover as the Indonesian National Standard of Gas Volume Flow Rate

Traceability is urgent to guarantee the truth of measurement, particularly for National Standard. Although a bell prover facility has established as the national low pressure gas flow standard of Indonesia since 2008, the measurement capability (15 to 1400 L/min, U95 = 0.20%) of the bell prover has not been traceable to SI Units. Moreover, displacement values provided by the bell prover’s manufacturer by rotary encoder method are still used. The limit detector by optical sensor to measure displacement is worthy to achieve dimensional traceability which can be switched by ultrasonic sensor for reasonable solution. The aim of this study is to improve the traceability of the bell prover by reasonable solution and then validate the gas volume flow rate measurement by inter-laboratory comparison. The Center for Measurement Standards (CMS), Industrial Technology Research Institute (ITRI), was invited to participate in the bilateral comparison, and a gas turbine flow meter was used as the transfer standard. The bell prover has been successfully traceable to SI units, particularly displacement measurement through flying start/stop method by limit of ultrasonic sensor (250 to 1200 L/min, U95 = 0.80% passing assessment report). Despite having larger uncertainty than manufacturer specification, the results are better for more in of layer comparison. Because the effect of turbine drift should be a concern, the gap of measurement time for inter-laboratory comparison is recommended to minimize as many as possible. Furthermore, the measurement range of bell prover should be reduced as reasonability purpose.

State Primary Standard of Gas Volume and Flow Rate Units for the Pressure Range of 1 MPa to 5 MPa (PVTt-15)

For the first time in Ukraine a primary measurement standard of gas volume and flow rate units in a pressure range of 1 MPa to 5 MPa has been created. The standard is based on realisation of the units by PVTt principle and units dissemination using critical Venturi nozzles. Gas passing through the nozzle during its calibration fills an evacuated collection tank located downstream the nozzle, and the respective time interval is measured. Mass flow rate is calculated by multiplying the volume of the collection tank by the gas density change and dividing by the tank filling time. Density values are determined by the equation of state and the measured initial and final pressure and temperature values. The structural and functional scheme of the measurement standard is shown in Figure 3.
 The standard consists of two units. The first unit is intended to realise, keep and transfer the units of gas volume and flow rate. The general view of the block is shown in Figure 4. The unit contains high pressure collection tank, precision water thermostat, vacuum pump, piston gas pressure gauge, flow switch, fine filter, a set of seven Venturi nozzles with diameters from 0.1 mm to 3.0 mm. The second unit is designed to form a stationary gas flow and provide a critical gas flow rate (at the speed of sound) at the nozzle throat. In the case of an elementary reversible adiabatic (isoentropic) process at a critical velocity, the mass flow rate of gas passing through the nozzle is maximally possible. The unit consists of equipment for reducing the pressure from 150 bar to 70 bar and from 70 bar to 10 bar, the heat exchanger and the instruments measuring the pressure and temperature of the gas flow. The created measurement standard will assure metrological traceability of the measurements of gas volume and volume flow rate at high pressures for the flow rate up to
 100 m3/h and calibration of the primary reference nozzles with a throat diameter from 0.1 mm to 3 mm.

Hollow fiber-based rapid temperature swing adsorption process for carbon capture from coal-fired power plants

Post-combustion carbon capture is one of the feasible methods to reduce emission of carbon dioxide (CO2) from coal-fired power plants. The biggest challenge in this technology is reduction of energy consumption. This work proposes a hollow fiber based rapid temperature swing adsorption (RTSA) method for capturing CO2 from typical coal-fired power plants. The proposed RTSA approach can shorten the operating time and using low-grade energy for regeneration of adsorption elements. In this study, the tank-in-series model is used to simulate the RTSA process including adsorption and desorption periods. A dual-column operating procedure is then used to treat the flue gas continuously from the coal-fired power plants. Main operating variables including inlet gas volume flow rate (0.1–0.2 m3/s), abandon time (0–10 s), desorption temperature (80–120 °C) on key performance factors such as discharge gas purity, capture ratio of CO2, and energy consumption per unit CO2, etc. are investigated for reducing the energy consumption. This study found that the inlet gas volume flow rate will significantly affect the capture ratio, where smaller gas volume flow rate would be beneficial to increase capture ratio. The abandon time obviously affects the purity of the captured CO2, where the longer abandon time leads to higher purity. Desorption temperature affects both the capture ratio and purity of captured CO2. The higher the desorption temperature, the greater the purity and capture ratio. For one typical basic unit with dual-column hollow fiber-based RTSA, the study found that when the inlet gas volume flow rate is 0.12 m3/s, the desorption waiting time is 7 s, and the desorption temperature is 120 °C, both the CO2 purity and capture ratio can exceed 90%. With considering the possibility of using steam in a low-pressure turbine as a source of heat required for Dual column vacuum RTSA (DC-vRTSA), the impact on the efficiency and stream data of typical coal-fired power plants are calculated. DC-vRTSA at 120 °C, 100 °C and 80 °C will reduce the efficiency of coal-fired power plants by 8.2%, 6%, and 3.4%, respectively.

A Source of Nonequilibrium Argon Plasma Based on a Volume Gas Flow Discharge at Atmospheric Pressure

A fundamental approach is considered and an effective source of a spatially homogeneous volumetric nonequilibrium plasma based on a glow discharge at atmospheric pressure generated in an inhomogeneous electric field is developed. The main advantages of this discharge were revealed: high combustion uniformity, economy, and the possibility of scaling the structure over a wide range, while increasing the stability of its operation and providing a more uniform and effective effect of non-thermal bulk plasma on heat-sensitive surfaces.

Analisa Pengaruh Diameter Impeller Terhadap Kapasitas Dan Penurunan Tekanan Blower Sentrifugal

Blower is a device used to increase or increase the pressure of air or gas that will be flowed in a particular room as well as suctioning certain air or gas where the Blower produces a relatively high pressure ratio with a greater volume of gas flow. At present the role of the Blower has begun to be widely used, especially in the engineering field, where the Blower role was created to facilitate the process of air exhaust. The blower itself is a producer of air movement which is generally used for ventilation. Blowers consist of several types, namely Axial Blowers and Centrifugal Blowers. Blowers have one component, namely Impeller. To determine the right diameter of the impeller, a performance test on centrifugal blowers with different variations in the size of the impeller diameter is needed, such as an anemometer, wattmeter and tachometer, and the impeller diameters are 180 mm, 190 mm and 200 mm with a rotational speed of 1500 rpm. The results obtained from testing on the diameter of the 200 mm impeller obtained the highest efficiency with a value of 0.0086%. The maximum air velocity is found in the diameter of the impeller with a size of 200 mm which is equal to 19.82 km / h. Then, the maximum pressure drop (∆p) is found at the diameter of the impeller with a size of 200 mm and 190 mm with the same result which is 136,206954 Pa. Then followed by the largest capacity value (Q) found in the variation of the diameter of the impeller with a size of 200 mm that is equal to 118.92 m3 / h. And the largest motor power is found in variations in the diameter of the impeller with a size of 200 mm that is equal to 62.85 W.

Wellhead metering based on bubble and resonance Coriolis effect with known gas-liquid ratio

Coriolis flowmeters are widely used in various industries for their high accuracy in density and mass flow measurement. However, for wellhead produced fluid with low gas content, its metering accuracy will be affected by entrained gas in the fluid. The bubble effect and increase of fluid compressibility have a major impact on the measurement results. In this paper, the influences of gas volume fraction and flow conditions on measurement deviations of Coriolis flowmeter are analyzed by Finite Element Analysis (FEA) method in case of low GVF that is lower than 10%. The deviations induced by the bubble effect and resonance effect under the influence of low gas content and flow conditions increase the metering errors of Coriolis flowmeters. The simulation results show that the deviations of fluid density increase negatively with the increase of gas content and the maximum deviation is 37.273%; the deviations of mass flow increase at first and then decrease, and the maximum deviation is −9.311%. A novel method based on correction model of the measurement deviations induced by bubble and resonance Coriolis effect with known gas-liquid ratio is proposed to accurately measure various parameters of wellhead produced fluid. The corrected results show that for the low gas content range (i.e. 0 to 10% GVF), the deviations of gas-containing fluid density and mass flow do not exceed ±0.3% and ±0.5% respectively, which are significantly lower than those before.

Comparisons of national standards in the field of gas flow rate and volume, gas flow rates from 20 to 6500 m3/h

The supplementary international comparison of national gas flow standards COOMET.M.FF-S9 was carried out from May 2019 to January 2020. The comparison were made in the range of gas flow from 20 to 6500 m3/h. Six European National Metrological Institutes (VNIIM-VNIIR, PTB, IFSM, BelGIM, LEI and LABSAGAS) took part in the comparison. The VNIIM-VNIIR acted as a pilot laboratory. The participants used for comparison the reference test rigs, implemented mainly on the basis of reference critical nozzles or reference flow meters. The transportable comparison standards (rotary and turbine flow meters) were used for the comparison procedure and in sequence were sent to the participants for testing. According to the results of the comparison, all participants confirmed their calibration and measuring capabilities in the declared flow ranges.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

CONSIDERATION OF CONDITIONS AND DIFFERENCES AT CALIBRATION AND APPLICATION FOR NATURAL GAS FLOW METERS

Improving the accuracy and reliability of natural gas registration is an actual problem for today. One of the main factors influencing on the measurement accuracy of gas volume and volumetric flow rate is mismatch calibration (verification) conditions of measuring instruments with conditions of their use. This discrepancy is due to differences in the calibration and using devices for measuring medium’s density, temperature and pressure that leads to significant uncertainty in the measurement results. The problem is caused by lack of the required metrology equipment for semi-natural calibration. To solve this problem is proposed to apply a hydrodynamic theory of similarity based on it define a complex criterion of similarity. Such a criterion is based on the numbers of Reynolds, Strouhal and Euler. After calibration with air at atmospheric pressure is determined complex criterion which is the basis for calculating the lapidary characteristics of the device for real operating conditions. The proposed approach makes it possible to predict the metrological characteristics of turbine type gas meters for different types of gases with high accuracy based on the calibration results of any of them; to evaluate the conformity limits for calibration characteristics of the turbine type gas meter at different parameters of the medium; verification (calibration) of the turbine type gas meter should be with the air at a pressure near to atmospheric and could be used for the calculation of natural gas at different pressure values. This improves the accuracy of natural gas measurement without verification the instruments during operation and creates the ability to diagnose measuring instruments on test benches using air as the medium.