Wet Gas Flow Research Articles

Calculation of the required methanol consumption during the flow of wet hydrocarbon gas in a horizontal pipeline

One of the main problems that have to be solved during the development of hydrocarbon deposits is the formation of gas hydrates in pipelines. In this regard, the article presents a preventive method to struggle against the formation of gas hydrate deposits on the pipes inner walls associated with the supply of a hydrate formation inhibitor to the gas stream. The research was conducted on the basis of a mathematical model of the wet hydrocarbon gas flow in a horizontal pipeline. The research object is to determine the minimum required consumption of methanol, in which there is no formation of gas hydrate deposits on the channel inner walls. The practical significance of this study is that it is aimed at reducing the risks associated with the formation of gas hydrates in pipelines. The numerical implementation of a mathematical model of natural gas flow in a horizontal channel is based on a sequential solution of a system of four differential equations by the Runge-Kutta method of 4 orders of accuracy, followed by a search for sequential approximations of the minimum inhibitor flow rate, in which the "gas + water ↔ gas hydrate phase" transition process does not occur on the inner surface of the channel. The article presents a calculation of the proportion of a hydrate formation inhibitor in the liquid phase by solving a cubic equation using the Cardano method. Based on the computational experiments results, graphs were constructed and interpreted of the dependencies of the minimum inhibitor consumption on the soil temperature, inlet gas pressure, total water concentration in the gas flow, initial gas temperature and total gas flow rate.

Soft measurement model for wet gas flow rate based on ultrasonic and differential pressure sensing

Non-separation measurement of gas–liquid two-phase flow is of great significance to industrial production and theoretical research on two-phase flow. In this paper, a soft measurement method of wet gas flow rate based on ultrasonic and differential pressure (DP) sensors is proposed. A total of 129 sets of experimental data are obtained in DN50 horizontal pipe, the superficial velocity of gas and liquid ranging from 5 m s−1 to 33 m s−1 and 0.015 m s−1 to 0.6 m s−1, respectively. Ten feature parameters of ultrasonic signals such as the time difference between two echoes and kurtosis factor are proposed from time and frequency domain. As well as the power spectral density, mean value and standard deviation value are analyzed based on DP signals. Furthermore, the Spearman correlation coefficient is introduced to evaluate these feature parameters quantitatively. And nine parameters which are highly correlated to gas–liquid flow rate are selected as the inputs of the soft measurement model. Finally, Decision Tree, least square support vector machines and artificial neural network (ANN) models are established through training with the experimental data. Comparison results show that ANN has the lowest prediction errors on the test set, with the mean absolute percentage errors of 1.49% and 3.2% for gas and liquid, respectively.

Devices and methods for wet gas flow metering: A comprehensive review

Wet gas is commonly encountered in various industries, including energy, chemical, and electric power sectors. For example, natural gas extracted from production often contains small amounts of liquid, such as water and hydrocarbon condensates, which classifies it as wet gas. The presence of liquid within the gas poses challenges for accurate flow measurement. To improve the performances of wet gas flow metering methods, significant research and development efforts have been invested into the wet gas flow metering technologies due to their vital importance in the production, transfer, and trade benefits.This paper presents a comprehensive overview of the recent development of wet gas flow metering. Firstly, a comprehensive discussion of the Lockhart-Martinelli parameter (Xlm) and its relation to the gas void fraction (αg) is presented, which was mostly overlooked in previous wet gas research work. The occurrence of various flow patterns in wet gas conditions at different orientations (horizontal and vertical) was explored. Following an investigation of pressure impact on the wet gas flow patterns and development of the wet gas regions, a different test matrix for further research work was suggested. After a novel classification of wet gas measurement methods, the paper offers a detailed comparison of differential pressure (DP) meters including Venturi, Cone meter, and orifice meters, by considering both liquid and gas flow rate measurements. Secondly, the paper discusses and compares vortex flow meters, Coriolis and ultrasonic meters in comparison to DP meters. Notable phase fraction meters are also examined and compared to one another. Thirdly, the paper reviewed the concept of existing and potential hybrid wet gas meters, conducting a detailed discussion and comparison with commercial solutions by evaluating their ranges and accuracies. This assessment provides valuable insights into the capabilities of these hybrid meters, highlighting their potential to enhance the measurement of wet gas flow rates.

Effect of Water Vapor on Hydrogen Isotopes Separation by Polymer Electrolyte Fuel Cell

IntroductionHydrogen isotopes are protium (H), deuterium (D) and tritium (T). D and T are important materials not only for fission and fusion reactors, but also for semiconductors since the strong hydrogen termination improves the durability. Various techniques for hydrogen isotope separation have been known for long time, but they have some drawbacks such as low separation efficiency and poor energy consumption. Therefore, new separation and purification methods are required.In polymer electrolyte fuel cell (PEFC), wettability is optimized well and small amount of Pt catalyst is used. The configuration is also key issue for the conventional method of water-hydrogen chemical exchange. Therefore, we investigated the effect of water in hydrogen isotope separation by PEFC [1].ExperimentalA mixture hydrogen gas of H2 and D2 was supplied to the PFEC. The separation factor for dry and wet gas flow was measured, respectively. Hydrogen gas and water vapor from PEFC were analyzed by quadrupole mass spectrometry (Q-mass) and Fourier infrared spectrometer (FTIR), respectively. The separation factor and mass balance were calculated.Results and discussionWhen no electricity was generated, FTIR results showed that D was enriched in water vapor. This is explained by a gas-phase chemical exchange reaction occurring on a platinum catalyst. When the PEFC was operated, the electrochemical reaction promoted the D separation. A large amount of D (about 45%) was transferred to water vapor during power generation. The separation factor was approximately 1.7, while it was approximately 1.3 for no generation. The present results suggested that gas-phase chemical exchange and the cell reaction had a synergistic effect on D separation.

Wet gas flow metering by combining a vortex flowmeter with disturbance wave frequency

Based on a conductance-vortex meter dual-modality system, a novel wet gas flow measurement method is proposed, which combines a vortex meter with disturbance wave frequency. A negative relationship between the vortex signal quality and the disturbance wave frequency is found, on which basis a new segmented fast Fourier transform–continuous wavelet transform vortex frequency extraction method is proposed. Uniform exponential equations are derived for meter over-reading, taking into account the liquid-phase Reynolds and gas-phase Weber numbers, the disturbance wave Strouhal number, density ratio, and the liquid-phase Reynolds number. Finally, a Newton–Armijo-based wet gas metering model is developed by combining these two correlation equations. The percentage errors (PEs) of the gas flow in wet gas are within ±1.0% error bands with uncertainty of 0.56%. The full-scale PEs of liquid flow are within ±10% error bands with uncertainty of 4.71%. The disturbance wave frequency is used to correct the meter over-reading. As no liquid film thickness calibration is needed, the proposed method has low requirements on the conductivity of the medium and hence the application scope of media could be expanded.

Experimental study on wet gas condensation heat transfer and flow resistance in horizontal intensified tube

The heat transfer and flow resistance characteristics of in-tube vapor condensation with high content non-condensable gas is significant for designing waste heat recovery devices of gas-fired boilers. In this paper, the forced convection condensation of wet gas in the horizontal tube is experimentally investigated with a non-condensable gas mass fraction of 83–95%. The condensation heat transfer coefficient, thermal resistance and pressure drop are compared between bare tube and two intensified tubes, i.e., the corrugated and spiral tube, under various Reynolds number, wall subcooling degree and inlet humidity. The results show that the in-tube condensation heat transfer coefficient increases with increasing Reynolds number and inlet humidity, but decreases with increasing wall subcooling degree. Compared with the bare tube, the heat transfer coefficient and pressure drop increase up to 47.13% and 16.00% respectively for the spiral tube, and 116.04% and 88.48% respectively for the corrugated tube. When combing the heat transfer and flow resistance factors, the maximum comprehensive performance coefficients are 1.71 and 1.44 for corrugated tube and spiral tube respectively. The superiority of corrugated tube in the wet gas condensation is benefit from effective breaking the non-condensable gas film and promoting the vapor diffusion on the interface.

Study on double differential pressure measurement method of gas-liquid two-phase flow in high gas content wells

The production of natural-gas wells contains natural gas and a small amount of liquid, which is a wet gas composed of oil, gas and water. For dynamically monitor the liquid and gas production from a single well, there is an urgent need for a low-cost, small-volume online metering device for wet gas flows through a single well. Aiming at the problem, this paper designs a wet gas flow measurement device for a long-throated Venturi tube based on the double differential pressure method. By combining experiments and numerical simulations, a matching flow calculation model was developed. Based on the experimental data of NEL's 6-inch standard Venturi tube wet gas over-reading, the numerical simulation method is used to carry out the research of high-pressure wet gas measurement under the pressure condition of 2, 4 and 6 MPa. The simulation results of two multiphase flow models, DPM and Euler, are compared with the experimental values of NEL. The results show that the maximum relative error is less than 10%, and the Euler model is more suitable for the numerical simulation of high-pressure wet gas. According to the actual production from the gas well, a long-throated Venturi tube with a throttling ratio of 0.5 and a diameter of DN50 was designed, and a numerical simulation study of wet gas under a pressure of 2, 3 and 4 MPa was carried out. Numerical simulation results show that the change laws of over-reading and liquid-gas mass ratios of high-pressure wet gas are consistent with those of low-pressure wet gas. The numerical simulation results are used to correct the flow calculation model of low-pressure wet gas, and a flow calculation model suitable for high-pressure wet gas in gas wells is obtained. The gas flow prediction accuracy of the flow calculation model was lower than ±3%, and the liquid flow prediction value was lower than ±10%. Compared with other measurement methods without separation of wet gas, the long-throated Venturi tube based on the double differential pressure method has a simple structure and low measurement cost. By further optimizing and expanding the measurement model, after improving the accuracy, it can be installed in the wellhead pipeline to monitor the oil and gas production from a single well in real time. This can provide support for gas reservoir exploitation decisions.

A Detection Method for Vortex Precession Frequency Based on MEMS Three-Axis Acceleration Sensor

Swirlmeters are widely used in the wellhead metering of low permeability gas fields in China. However, the swirlmeter’s piezoelectric sensor has difficult distinguishing the vortex precession signal from fluid pulsation noise, pipeline mechanical vibration, and other interference. In this article, in order to detect the vortex precession frequency signal effectively and accurately from the interference noises, a signal detection method based on micro-electro-mechanical systems (MEMS) three-axis acceleration sensor was proposed. According to the difference between the force direction of vortex signal and interference signals, a dual-differential technique based on three-axis measurement is proposed to eliminate interference noises. The radiated interference of electromagnetic noise was eliminated by adding a notch circuit and radio frequency interference filter to the measuring circuit. Then, the sensitivity characteristics of vortex precession with different swirl angles were investigated by numerical simulation and the performance of the method was evaluated by experiments. The results of experiments show that the method proposed in this article can improve the sensor’s capability of anti-interference and widen the measurement range. Further wet gas experimental results show that the vortex precession frequency signal detected by MEMS-three-axis acceleration sensor (TAAS) does not change its linear output law in spite of the presence of liquid phase. Finally, a correction model of the instrument coefficient of the swirlmeter for wet gas measurement was established. The relative errors of the fitting model are within ±2.0%, the mean percentage error (MPE) is 0.17%, and the mean absolute percentage error (MAPE) is 0.81%. The method proposed in this article can improve the ratio of signal to noise of swirlmeter, overcome the influence of interference noise on the precession frequency, and broaden the gas flow measurement range. It realizes the efficient and accurate measurement of the gas flow rate for wet gas flow.

A Novel Method for Wet Gas Flow Measurements Based on an Over-Reading Principle

A novel method to measure the flow rate in a wet gas is presented. Due to the presence of liquid, there is a deviation in the measurement of the gas volume flow rate obtained with standard vortex flow-meters. The proposed method is based on a correction factor determined through the application of an over-reading approach to a bluff body in mist flow. The correction factor is obtained from the slip velocity ratio, i.e., the ratio of droplet velocity to gas velocity, based on the analysis of the fluid velocity distribution in the pipeline section. It also takes into account relevant theoretical arguments. It is shown that the predicted results fit the experimental results well.

Adjustable Cone Meter Adapts Automatically to Wet-Gas Conditions

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 207505, “Using an Adjustable Cone Meter To Measure Wet Gas,” by Sakethraman Mahalingam, SPE, Saudi Aramco; Gavin Munro, SPE, GM Flow Measurement; and Muhammad Arsalan, SPE, Saudi Aramco, et al. The paper has not been peer reviewed. _ A traditional fixed-size Venturi meter has a turndown of approximately 8:1 under dry-gas conditions that may drop to as low as 3:1 under wet-gas flow. When the well conditions change, a replacement of the original Venturi meter with one of a different size is needed. In the complete paper, the authors present the design, development, and testing of an adjustable cone meter that has the ability to adapt itself to flow conditions automatically and provide a turndown of as much as a 54:1 under dry-gas conditions and as much as 20:1 under wet-gas conditions. Adjustable Cone Meter Design The adjustable cone meter is a variation on a traditional differential pressure cone meter. A moveable sleeve is placed within the meter, and its position is moved using a rack-and-pinion arrangement. When the flow rate is high (Fig. 1a), the sleeve is downstream of the cone and the meter operates like a normal cone meter. This means that the differential pressure at the cone (P1–P2) is sufficiently high and within the measurable range of the meter. When the flow rate drops below a preset value, however, the differential pressure (P1–P2) drops below the measurable range of the meter. While a conventional cone meter would be unable to measure such flow rates, the adjustable cone meter is able to achieve accurate measurements because the meter detects that the differential pressure is below the measurable range and moves the sleeve automatically so that it covers the cone (Fig. 1b). This reduces the internal diameter of the flowline around the cone and causes the differential pressure to move into the measurable range. The meter then uses the differential pressure to again produce accurate flow measurements. In addition, the meter has a second differential pressure sensor downstream of the cone. This is used to measure the liquid fraction of the wet gas. Meter Design Exhaustive finite-element analysis (FEA) was conducted to determine the operating stresses within the meter body and its pressure-containing components during operation. The sliding sleeve can maintain full line pressure and features double-pressure seals at either end, safely containing fluids inside the flowline. The primary risk is the deformation and failure of the sliding sleeve because it is a thin metal structure. However, FEA established the minimum working pressure of at least 1,200 psi for the sleeve, gearbox, and meter body, using industry-standard safety factors. Cone meter calculations are provided in the complete paper.

A new correlation to determine the Lockhart-Martinelli parameter from vertical differential pressure for horizontal venturi tube over-reading correction

Venturi tubes are widely used to measure the gas flow rate in a wet-gas stream. To calculate the gas flow rate, wet-gas Venturi tubes require the liquid loading (i.e. Lockhart-Martinelli parameter) to be known as an input to a so-called over-reading correction correlation. It is challenging to derive the Lockhart-Martinelli parameter without installing additional devices in series to the Venturi tube thus adding significant cost and complexity. A relatively low cost and easy to implement method is to derive the Lockhart-Martinelli parameter by measuring the pressure drop across the Venturi tube or along a pipe section. A correlation that predicts the Lockhart-Martinelli parameter by measuring the pressure drop along a vertical pipe section downstream of the Venturi tube is presented. The correlation was obtained by fitting experimental results from TUV-SUD National Engineering Laboratory's wet-gas test facility with nitrogen-water in a 4″ vertical pipe, Lockhart-Martinelli from 0.04 to 0.29, and gas Froude number from 1 to 2.7. Further experiments were conducted at Spirax Sarco Engineering plc to evaluate the performance of the proposed correlation under steam-water conditions. Tests were conducted with steam-water in a vertical 2″ pipe, Lockhart-Martinelli from 0.005 to 0.064, and gas Froude number from 0.55 to 1.35. The Lockhart-Martinelli parameter is predicted within ±0.035 absolute value with the proposed new correlation for both the National Engineering Laboratory and Spirax Sarco datasets. Gas flow rate values within approximately ±5% error are obtained with the proposed correlation together with ISO/TR 11583 over-reading correlation for the NEL dataset. Although further improvements to the proposed method are required, this work demonstrates the efficacy of an agile, simple, and low-cost differential pressure method to aid the Venturi meter to determine the gas mass flow rate in wet-gas flow.

Fog Droplet Collection by Corona Discharge in a Needle–Cylinder Electrostatic Precipitator with a Water Cooling System

In this study, a needle–cylinder electrostatic precipitator with a water cooling system was designed to enhance the harvest of atmospheric water in wet flue gas. The effects of flow rate, temperature and particles on the collection of fog droplets were investigated. Meanwhile, the energy efficiency of water collection was analyzed at different voltages. The results show that the current decreases with the increase of air relative humidity under the same voltage, and the breakdown voltage increases obviously. Concurrently, by appropriately reducing the wet flue gas flow velocity, the residence time of fog droplets in the electric field can be increased, fully charging the droplets and improving the water collection efficiency. Moreover, experiments revealed that through decreasing the flue gas temperature, both the water collection rate and energy efficiency can be improved. In addition, the presence of particles in wet gas can improve the water collection rate by 5~8% at different discharge voltages. Finally, based on energy efficiency analysis, with the increase of voltage, although the water collection rate increased, the energy efficiency decreased.

Modeling the flow rate of dry part in the wet gas mixture using decision tree/kernel/non-parametric regression-based soft-computing techniques

Owing to its importance in extraction of natural gas from underground gas storage as well as its crucial role in determination of final gas mixture in the production facilities of gas/oil industry, the dry content of wet gas mixture needs to be calculated precisely. The present study explores the potential of different soft-computing techniques in estimation of the dry gas flow rate (kg/h) (output variable) of wet gas mixture based on two input variables of wet gas flow rate (kg/h) and absolute gas humidity (g/m3). Decision tree-based methods (M5P tree, random forest (RF), random tree (RT), and reduced error pruning tree (REPT) models), kernel function-based approaches (Gaussian process regression (GPR) and support vector machines (SVM)), and non-parametric regression-based technique (multivariate adaptive regression splines (MARS)) were implemented for the first time to estimate the dry gas flow rate, and their respective prediction performances were analyzed statistically. Coefficient of correlation (CC), Nash–Sutcliffe efficiency (NSE), root mean square error (RMSE), mean absolute error (MAE), Legates and McCabe's index (LMI), and Willmott's Index (WI) were used as the statistical indicators for validating the performance of each soft-computing model. While M5P model (MAE = 122.2382 kg/h, RMSE = 580.5626 kg/h, CC = 0.9875 for the testing data set) was better than other tree-based models (MAE = 363.2802–542.6119 kg/h, RMSE = 871.9363–1025.3444 kg/h, CC = 0.9587–0.9706 for the testing data set) and MARS model (MAE = 128.0083 kg/h, RMSE = 622.9515 kg/h, CC = 0.9852 for the testing data set), the statistical indicators approved the superiority of the radial basis kernel function-based GPR model (GPR-RBKF) model (MAE = 163.3266 kg/h, RMSE = 483.1359 kg/h, CC = 0.9915 for the testing data set) over other implemented models in predicting the dry gas flow rate. The findings highlighted the potential of soft-computing methodologies in precise estimation of dry gas flow rate in wet gas mixture, particularly, in situations where the measurement of such parameters with traditional deterministic models is practically not possible.

A new two-fluid model for flow rate measurement of annular flow in horizontal pipe

Non-separation measurement is a research difficulty and hotspot in multiphase flow. In this paper, the multimodal ultrasonic sensors and differential pressure transmitter combined with two-fluid model are used to measure the wet gas flow rates under non-separation state. Firstly, a modeling measurement system is built. The liquid film thickness and pressure drop are obtained by using ultrasonic sensor and differential pressure transmitter. Based on the steady-state one-dimensional two-fluid model and the limitations of existing models, a new prediction model is proposed. Comparing the pressure drop data obtained by new two-fluid model with the experimental data, the errors are within ±30%. Then, wet gas flow rates measurement system is constructed. The liquid film thickness and gas velocity are measured by using multimodal ultrasonic sensors. Combined this new two-fluid model, the wet gas flow rates are obtained. The measurement errors of gas and liquid flow rate are within ±10% and ±15%.

Numerical modeling of a membrane humidifier for mechanical ventilation

Dry gas inhalation can harm the mucous layer of the respiratory tract. For mechanically ventilated patients the inhalation gas must get humidified before inspiration due to the preservation matter of thickness and wetness of the mucus layer. In this study, an air-to-air planar membrane humidifier is replaced instead the bubble humidifier for ventilators. Comprehensive numerically investigation is performed for a mechanical ventilation system for 8 ml/kg tidal volume. Studies are performed to specify the effects of the respiratory rate, wet gas inlet temperature, flow rate and humidity and cell numbers of membrane humidifier. Results show that increasing the body weight and the respiratory rate decreases the humidifier performance due to the addition of tidal volume. More wet gas flow rate and humidity achieve more performance and wet gas temperature in the most effective variable on the delivery air parameters. By increasing the humidifier cell number at the fixed tidal volume and wet gas flow rate performance increases. A multicell membrane humidifier exhibits lower pressure drop and wider rang coverage of tidal volumes. Studied membrane humidifier can provide up to 1900 ml/inspiration with an 8-cell membrane humidifier for tracheal intubation.

Online Measurement of Gas and Liquid Flow Rates in Wet Gas Using Vortex Flowmeter Coupled With Conductance Ring Sensor

Wet gas flow commonly exists in several industries. The online measurement of gas and liquid flow rate is beneficial for economic efficiency. A combination of vortex flowmeter and liquid film sensor was proposed for two-phase flow measurement of wet gas. The specific form is as follows: the dual-modality sensing system was designed and calibrated by an annular mist flow loop. The fluid materials are pure air and water liquid. The ranges of operating pressure, the superficial gas velocity, and superficial liquid velocity are 1.5 bar–3.5 bar, 18.86–37.73 m/s, and 0.0028–0.028 m/s. Then the function relations of liquid film thickness and vortex frequency, with gas and liquid Weber numbers were built, respectively. Finally, a novel model for calculating gas and liquid flow rates in wet gas measurement was established, and solved by the Newton iterative algorithm. It showed that the percentage error (PE) of gas flow rate predicted by the model is within ±1.5%, and the mean absolute percentage error (MAPE) is 0.55%. The full-scale PE of liquid flow rate is within ±5% and the MAPE is 3.48%. The data show that this solution for gas and liquid flow rates measurement of wet gas by combining a vortex flowmeter with a conductance ring sensor is feasible.

CFD study of the transient wet gas flow behavior through orifice plate flow meters

Differential pressure flow meters are widely used in wet gas flow measurement, typically, combined with a method to determine the liquid fraction. An alternative with significant advantages for industry, in term of cost, operation and maintenance, is determining the liquid fraction based on its relation with the statistical parameters of transient differential pressure signal fluctuations. In this way, a single measurement device can provide mass flow rate and liquid fraction simultaneously. For this method to be more feasible in the wet gas flow measurement, it is essential to understand how the differential pressure signal fluctuations and the gas–liquid flow behavior at the restriction are correlated. On this basis, this paper presents a transient 3D Computational Fluid Dynamics (CFD) study of the wet gas flow through an orifice plate, operating under field conditions, using the two-fluid model. Steady-state results, calculated from the time averaging of the transient solution, for the over-reading OR parameter were validated with experimental field data and results obtained by correlations available in the literature, showing very good agreement. The transient results from simulations presented a trend in agreement with experimental data from the literature, showing a positive correlation of the standard deviation of differential pressure signal with liquid fraction upstream of the orifice plate. However, these results should be analyzed qualitatively due to model limitations, mainly related to the interfacial transfer closure in gas–liquid flows with changing phase morphologies. Despite this fact, some important insights regarding the 3D transient flow structure with a practical value were obtained from the model.

High-gas-volume-fraction measurement of wet gas using a gamma-ray sensor at different mounting angles

With the development of oil and gas fields in the South China Sea, the focus is on measurement accuracy pertaining to wet gas around subsea wellheads. Owing to limited space and safety with regard to subsea installations, the horizontal installation of a wet gas meter is preferred. However, the phase distribution of wet gas with a high gas volume fraction (GVF) in a horizontal pipe is non-homogeneous and causes uncertainty in the measurement of void fraction using the single-beam gamma-ray method. To resolve this issue, this study aims to determine a sensor position to best estimate the gas void fraction of a wet gas flow. An experiment was designed and conducted to study measurement results by mounting a gamma-ray sensor at different angles. A computational fluid dynamics numerical simulation was performed to investigate the phase distribution at the Venturi throat, and the resulting GVF based on the slip ratio and void fraction was used for comparative analysis considering the input void fraction as reference. The comparative analysis shows that the measurement errors at mounting angles of 0° and 90° are large in numbers, and optimal results are achieved at 45°. Therefore, to obtain accurate measurement results in horizontal pipes, an optimal mounting angle of gamma-ray source and detector relative to horizontal is recommended for the single-beam gamma-ray void fraction measurement method.

Wet gas measurements of long-throat Venturi Tube based on forced annular flow

A wet gas dual-parameter measuring device composed of a cyclone and a long-throated Venturi tube is proposed to overcome the difficulty of measuring the liquid content of wet gases and reduce the error caused by the wet gas flow pattern. The flow pattern is transformed into an annular flow by a cyclone. In this study, the proposed device was compared with a traditional non-cyclone long-throat Venturi tube; furthermore, the pressure difference ratio W between the contraction and expansion sections of the long-throat Venturi tube was introduced as a parameter. Through numerical simulations, the relationship between W, the gas Froude number, over-reading, and liquid-gas mass flow ratio was analyzed, and a new wet gas flow measurement model was established. The reliability of the measurement model was verified through indoor experiments. The experimental results showed that the traditional wet gas measurement device had gas phase and liquid phase errors of ±4.5% and ±10%, respectively; on the other hand, the cyclone-based wet gas measurement device had gas phase and liquid phase errors of ±3% and ±8%, respectively. Thus, the performance of the wet gas measurement device with the cyclone was higher than that of the traditional wet gas measurement device.

The Influence of Droplet Dispersity on Droplet Vaporization in the High-Temperature Wet Gas Flow in the Case of Combined Heating

The change in the thermal and energy state of the water droplet is defined numerically. The influence of droplet dispersity on the interaction of the transfer processes was evaluated. In influence of the Stefan flow was considered as well. The internal heat transfer of the droplet was defined by the combined heat transfer through effective conductivity and radiation model. The results of the numerical modeling of heat and mass transfer in water droplets in a wet flue gas flow of 1000 °C highlight the influence of the variation in heat transfer regimes in the droplet on the interaction of the transfer processes in consistently varying phase change regimes. The results of the investigation shows that the inner heat convection diminishes intensively in the transitional phase change regime because of a rapid slowdown of the slipping droplet in the gas. The radiation absorption in the droplet clearly decreases only at the final stage of equilibrium evaporation. The highlighted regularities of the interaction between combined transfer processes in water droplets are also valid for liquid fuel and other semi-transparent liquids sprayed into high-temperature flue gas flow. However, a qualitative evaluation should consider individual influence of dispersity that different liquids have.