Wet Gas Streams Research Articles

Parametric and modelling study of H2O-induced plasticization in PEI-TFC membrane for gas dehydration

Separation of moisture from gaseous mixtures, such as natural gas, humid air in food and goods storage warehouses or in sports halls and so on is of great importance. In this article, the separation of water from a wet gas stream is carried out by a TFC membrane made by interfacial polymerization on the sublayer of porous polyetherimide hollow fibers. Then the key-parameters affecting membrane efficiency is studied. The outcomes show that increasing the concentration of MPD has a substantial effect on enhancing the membrane water vapor flux. Moreover, it is disclose that increasing the concentration of TMC has the greatest effect on reducing nitrogen gas permeability and increasing the selectivity. Our findings reveals that disregarding the very low concentration of water vapor in the feed, shows a great impact on the permeance of each component compared to the pure state. Also, based on the modelling, it is obvious that for nitrogen gas in the entire pressure range, the adsorption mechanism is almost completely controlled by the Henry model, while the Langmuir adsorption mechanism is controlling for water vapor at low pressures, although at high pressures, the Henry mechanism has absolute superiority. Surprisingly, the H2O-induced plasticization impact on nitrogen permeance is more intense than on water vapor permeance. According to the modeling outputs, it is revealed that because D N2 is one to two order of magnitude lower than DH2O, water vapor permeance is much higher than that of nitrogen.

Enhancement of NOx adsorption performance on zeolite via a facile modification strategy.

Adsorption is a promising technology for simultaneously capturing nitrogen oxides (NOx) from flue gases and recycling NO2 as a profitable chemical, for which a robust and efficient adsorbent provides the key step for success in practical applications. This work reports the enhancement of NOx adsorption performances with less cost of desorption energy on Cu-ZSM-5 zeolites prepared by a facile and rapid (690s) modification method, the incipient-wetness impregnation coupled with microwave drying (IM). In comparisons to H-ZSM-5, Na-ZSM-5 and conventionally liquid-phase ion-exchanged counterparts under sub-1000ppm NOx feed concentrations and room temperature, the IM sample renders a record NOx adsorption capacity (qt,NOx) of 0.878mmol/g from dry gas stream on zeolites, and an applicable qt,NOx of 0.1mmol/g from wet gas stream with a proper copper loading (2.1wt%). The temperature programmed desorption of NOx on the optimal IM sample saturated with NOx from wet gas stream exhibit primary peak temperature lower than reported Cu-ZSM-5 and significant NO2 proportion (72.6%) in desorbed NOx. Deeper insights into advantageous NOx oxidative adsorption over the properly-loaded Cu-ZSM-5 in terms of diverse adsorbate states and competitiveness towards H2O were gained, showing IM method a promising sorbent improvement strategy for practical use.

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.

Fabrication of silica aerogel and carbon–silica composite for dynamic adsorption of benzene from dry and wet gas streams

ABSTRACT In the present study, the white kaolin-derived silica (SA) and silica-carbon aerogel composite (CSA) were successfully synthesised as useful adsorbents for the effective removal of benzene from dry and wet gas streams. The physicochemical features of the adsorbents were characterised using SEM, BET, XPS, and TGA, and the adsorption properties of benzene were investigated through breakthrough time curves and equilibrium study. The specific surface areas of SA and CSA were 628 and 783 m2 g−1, respectively, demonstrating the high porosity of the synthesised adsorbents. The dynamic adsorption and isotherm performances of SA and CSA confirmed that both adsorbents have superior adsorption properties and Khan isotherm for both developed adsorbents were the fittest model among the two- and three-parameter isotherm models studied and provided a maximum adsorption capacity of 366.2 and 224.4 for SA and CSA mg g−1, respectively. Furthermore, the reusability tests revealed that the SA and CSA could be efficiently recovered at 180°C. Our experimental outcomes indicated that the prepared SA and CSA can be applied as efficient and inexpensive adsorbents for the removal of benzene from gaseous streams.

Invariant method for measuring wet gas flow rate

The article deals with one of the important tasks of modern flow measurement, which is related to the measurement of the flow rate and the amount of wet gas. This task becomes especially important when it becomes necessary to obtain information about the separate amount of the dry part of the gas that is contained in the form of a mixture in the wet gas stream. The paper presents the principle of operation and structure of the invariant system for measuring the flow rate of wet gas, which is based on the combined use of differential pressure flowmeters and Coriolis flowmeters. The operation of the invariant wet gas flow rate measurement system is based on the simultaneous application of the multichannel principle and the partial flow measurement method. Coriolis flowmeters and the differential pressure flowmeter are used as the main elements of the system. The proposed measurement system does not offer applications for gases with abundant drip humidity. The article provides information about the test results of the proposed invariant system. The estimation of the metrological characteristics of the invariant system when measuring the flow rate of wet gas is given. The obtained test results of the invariant wet gas flow rate measurement system are relevant for natural gas production, transportation, and storage facilities.

Multicomponent Spinel Oxide Solid Solutions: A Possible Alternative to Platinum Group Metal Three-Way Catalysts

Single-phase quaternary spinel solid solutions, Cu0.05Ni0.95AlyCr2–yO4 (0 ≤ y ≤ 2.0), were prepared over the whole range of y by a polymerized complex method to study as platinum group metal-free three-way catalysts (TWC). Most conventional binary and/or ternary spinel oxides lose their NO reduction activity in the presence of water vapor and/or after high-temperature aging. In contrast, the present quaternary system with y = 1.8, which was aged at 900 °C for 25 h, preserved high activity even under a wet gas stream (5% H2O) simulating real TWC conditions. Comprehensive structural analyses via X-ray absorption fine structure and X-ray Rietveld analysis showed that, in the quaternary system, Cu and Cr prefer to occupy the tetrahedral site and the octahedral site, respectively, whereas Ni and Al are distributed across both sites. The partial replacement of Cr by Al increased the specific surface area from 7 m2 g–1 (y = 0) to 36 m2 g–1 (y = 1.8), which is a common feature of the NiAl2O4-based spinel platform...

Fouling of Impurities in Desulfurized Flue Gas on Hollow Fiber Membrane Absorption for CO2 Capture

Membrane-based absorption shows numerous potential applications for CO2 capture from flue gas. However, during the process, membrane fouling is not only caused by the wetting but also induced by gaseous components (SOx, NOx, and water vapor) and fine particles in the flue gas. In this work, the synergetic effects of water vapor coupling with SOx and NOx as well as the fine particles were investigated to better understand the membrane fouling and the performance of polypropylene hollow fiber membrane modules for CO2 capture in actual industrial conditions. The CO2 removal efficiency and the mass-transfer rate over time were studied under different feed gas flows of various gaseous composition schemes. The membrane performance suffered from a notable decrease after exposure to SO3 and particles, and in a wet gas stream, the effects of SO3 and particles were irreversible, whereas the influence of SO2 and NO2 can be recovered by N2 sweeping. The characterization results of membrane modules confirm that the me...

Grabbing CO2 from wet gas streams

Separation Membranes It is a challenge to extract CO2 from typical gas streams, such as the flue gas from a power plant. This is because any water in the stream tends to prevent CO2 absorption and may also degrade the absorbing material. Datta et al. developed a microporous copper silicate that avoids these problems. Most other materials have sites that absorb both water and CO2 at the same sites, and in that fight, the water tends to win. Although their material still absorbs water, it has separate sites for the CO2 absorption. It also shows good stability despite the absorbed water and can be reused. Science , this issue p. [302][1] [1]: /lookup/doi/10.1126/science.aab1680

One-Dimensional Formulation for Heat and Mass Transfer in Solid Desiccant Dehydration of Natural Gas

An analysis of heat and mass transfer in the dehydration of natural gas using solid desiccants has been carried out, leading to a mathematical model for the simulation of the dehumidification process of a wet gas stream flowing through a porous bed containing desiccant particles. The process is divided in two periods: one for adsorption, in which the gas stream is actually dehydrated, and another one for the regeneration of the desiccant material, both of which are cyclically applied. The mathematical model considers spatial dependence in the flow direction, such that heat and mass transfer resistances within particles are treated in a lumped capacitance fashion. The resulting formulation constitutes a system of four coupled equations for describing temperature and humidity fields within solid particles and in the gas stream. These equations are normalized in terms of physically meaningful dimensionless groups, and numerically solved for producing simulation results for different configurations. The results suggest that the duration of regeneration periods can be shorter than those for adsorption, and that this dependence is clearly influenced by the regeneration temperature. In addition, it is seen that larger operation pressures can lead to larger water concentration in the adsorbed phase, and hence higher dehumidification levels.

High temperature steam investigation of cobalt oxide silica membranes for gas separation

In this work we investigate the effect of high temperature steam on cobalt and cobalt oxide derived silica with an aim to providing an understanding of the permeation and gas separation performance of cobalt silica membranes exposed to simulated industrial wet gas streams. Cobalt silica (CoSi) and cobalt oxide silica (CoO x Si) xerogels were synthesized and exposed to steam at 500 °C for varying time periods. Subsequent characterization with FTIR and N 2 adsorption revealed that CoO x Si xerogels were significantly more hydrostable than CoSi xerogels, with few structural changes observed and only moderate densification (∼43%) of the CoO x Si matrix experienced even after the longest steam exposure. In comparison the CoSi matrix experienced severe densification (∼89%) after only short term steam exposure. CoO x Si was therefore selected as the optimal material for further membrane tests and CoO x Si membranes were subsequently synthesized using sol–gel techniques and exposed to steam in both high temperature long term stability studies and during temperature cycling tests. Exposure to steam had an adverse effect on membrane performance with the largest effect occurring during the initial stages where He permeance dropped from 3.95 × 10 −8 to 2.05 × 10 −10 mol m −2 s −1 Pa −1 and He/N 2 ideal selectivities from 123 to 45, respectively after 135 h of testing. However, following this initial period of steam conditioning, these membranes were able to oppose further deterioration and maintain acceptable steady state performance. Further tests with an increased steam rate showed that nitrogen permeation decreased more significantly than helium, leading to a rise in membrane ideal selectivity, suggesting that steam was competitively blocking the pores available to nitrogen adsorption and/or reducing the diffusion of nitrogen. Steam testing under cycling temperature conditions showed that below 400 °C, the membrane ideal selectivity was low. However, above 400 °C the membrane consistently exhibited a molecular sieving mechanism. In addition water permeation through the membrane varied with temperature suggesting that the membrane matrix continuously underwent reversible structural modification by the combined effect of water and temperature.

H2S photodegradation by TiO2/M-MCM-41 (M = Cr or Ce): Deactivation and by-product generation under UV-A and visible light

M-MCM-41 molecular sieves (M=Ce or Cr) were prepared by a hydrothermal method and impregnated with TiO2. The materials were characterized by XRD, N2 adsorption–desorption, DRS and XPS. Their potential application to photooxidize H2S in a wet gas stream was tested in a continuous flow reactor operating at a flow rate of 110mLmin−1 at 50% relative humidity and using 30ppmv of the pollutant. The photocatalytic efficiency using UV-A and visible light was compared to the activity of TiO2/MCM-41 without heteroatoms incorporated into the MCM-41 structure. It was found that the incorporation of Ce did not improve the performance of TiO2/MCM-41, but Cr-containing samples presented higher initial efficiency and were able to photooxidize H2S without formation of SO2 as a by-product, in contrast to the other prepared samples and to Degussa P-25 TiO2. Moreover, no other gaseous by-product was detected. The isomorphic incorporation of Cr into the structure of MCM-41 followed by TiO2 incorporation produced photocatalysts that presented good adsorption capacity and were much more active under visible light than under UV-light. This performance represents an important advantage for solar applications. Their photoactivity depended on the concentration of chromium; the highest efficiency was attained with samples with a Si/Cr ratio of 50. Finally, deactivation was observed as a consequence of sulfate accumulation on the surface of the catalyst and reduction of Cr6+.

Activated carbons modified with aluminium–zirconium polycations as adsorbents for ammonia

Microporous/mesoporous wood-based activated carbon was modified by impregnation with aluminium–zirconium oxycations and calcined at 300 °C, and then used as an adsorbent of ammonia. Water was present either on the carbon or in the gas phase. The initial (before ammonia adsorption) and exhausted materials were characterized using adsorption of nitrogen, potentiometric titration, XRD, FTIR and thermal analysis. Aluminium–zirconium polycations improve ammonia uptake by providing new Brønsted acidic centers that form strong interactions with the adsorbed gas in its protonated form. When calcined, the capacity of the impregnated carbon is reduced in dry air stream but increased in wet air stream. Indeed, for this sample, when exposed to dry gas stream, only Lewis acidic centers (associated with the presence of alumina and zirconia formed during the calcination process) are involved, and they lead to weaker interactions with ammonia. On the contrary, under wet gas stream, Brønsted acidic centers are also present and provide stronger interactions with ammonia. It was also evidenced that impregnation with polycations has a “screening” effect on the carbon surface by protecting it from the oxidative effect of hot air when the sample is calcined.

Immobilization of CO 2 by aqueous K 2CO 3 using microfibrous media entrapped small particulates for battery and fuel cell applications

This work focuses on developing a new adsorptive material and regenerable system for CO 2 sequestration to supply CO 2-free gas stream for low temperature and low carbon dioxide concentration applications, such as alkaline fuel cells, metal-air batteries, and portable air-purifying respirators. A novel microfibrous media has been introduced for carbon dioxide filtration from wet gas streams at room temperature. The use of microfibrous media in a composite bed maximizes the breakthrough capacity per unit volume and promotes high accessibility. The microfibrous media synergically combines the high contacting efficiency of the microfibrous matrix and the small internal mass transfer resistance of small particulates. The carbon dioxide adsorption capacity of the microfibrous media can be reversibly recovered. The incorporation of microfibrous media to the sodalime was observed. The result shows 120% improvement in the breakthrough capacity compared with the packed bed of the sodalime with the same volume. This approach can be applied to miniaturize the reactor and reduce thermal mass enhancing process intensification.

Overview: Artificial Lift (May 2006)

For the past several decades, artificial lift has referred to the traditional technologies of downhole pumping (e.g., sucker rod, electrical submersible, progressing cavity, and others) and gas lift. Today, a broader definition is emerging, a definition that can encompass the fundamental changes occurring in our industry. Today, artificial lift is no longer limited to methods applied in the wellbore, but instead must include methods used throughout the production system to "lift" the produced fluids to their final destination. For example, gas and heavy oil constitute a much larger portion of today's energy mix, driving significant changes in development philosophies. Today's heavy-oil developments make extensive use of multiphase production with long multiphase flowlines to tie wellsite production back to centralized processing facilities. Pressure losses in the surface multiphase gathering system can be significant, and a combination of downhole pumps and surface multiphase pumps often is required to effectively "lift" the fluids to the processing facility. Key issues for heavy-oil artificial lift include handling produced sand, increasing volumes of gas, and the high temperatures associated with thermal recovery projects. The booming natural-gas business has focused attention on artificial lift in gas and wet-gas developments. At the surface, wet-gas gathering systems have been found to provide advantages in terms of reduced capital expenditures and complexity. In this case, an important component of artificial lift is the boosting of the wet-gas stream through surface flowlines, which in the future may take the form of multiphase pumps and wet-gas compressors. In the wellbore, problems associated with lifting liquids from gas wells are well known. Today, several newer methods are being applied, such as the combination of flow-enhancement chemicals (e.g., surfactants) with downhole flow-enhancement tools. Deep water, ultradeep water, and other remote resources also have forced a broader definition of artificial lift. For deepwater and ultradeepwater developments, flow in risers and long subsea flowlines represents an important component of the production system. Intervention issues associated with subsea wells severely limit application of wellbore artificial-lift methods. Therefore, artificial lift is increasingly taking the form of seafloor multiphase-pumping and riser-lift methods. When searching for an artificial-lift solution, a wide variety of methods now must be placed "on the table" alongside the traditional methods we have used for decades. Artificial Lift additional reading available at the SPE eLibrary: www.spe.org SPE 95620 "ESP Model Implementation and Result Analysis Under Gas/Liquid Flow Conditions," by D. Sun, SPE, Baker Atlas, et al. SPE 97275 "Effect of Operating-Valve Performance on Stability of Gas Lift Wells," by Y.V. Fairuzov, SPE, Natl. Autonomous U. of Mexico, et al. SPE 93594 "Electrical Submersible Progressing-Cavity-Pump Application in Kulin Horizontal Wells," by M. Taufan, SPE, P.T. Caltex Pacific Indonesia, et al.

Adaptive calibration of a capacitance tomography system for imaging water droplet distribution

A highly sensitive electrical capacitance tomography (ECT) system based on an HP4284 impedance analyser has been developed and used to quantify low concentration multi-phase flows in wet gas separation processes. The system hardware provides high accuracy (0.05%) and high resolution (10 −17 F). The sensor was calibrated in an environmental chamber with solid samples of known permittivity over ranges of temperature and humidity. Adaptive calibration and adjacent electrode pair correction techniques were applied to image very low concentration profiles. This paper describes the techniques used and presents the experimental results obtained from a test flow rig called Twister, which has been designed to separate liquid droplets from wet gas streams. The test results over a range of operating conditions (20–95% humidity) demonstrate that the ECT system is capable of reconstructing clear images of the droplet distribution inside Twister. Changes as small as 1 gWater/kgAir in the form of liquid droplets were detectable. It has also been shown that the concentration of the condensable phase can be estimated quantitatively within 20% in comparison with the reference measurements.

Gas-Liquid Cylindrical Cyclone (GLCC©) Compact Separators For Wet Gas Applications

Gas-Liquid Cylindrical Cyclone (GLCC©1) separators are becoming increasingly popular as attractive alternatives to conventional separators as they are simple, compact, less expensive, have low-weight, and require little maintenance. However, present studies focus on GLCC designs and applications at relatively lower gas velocities (below the minimum velocity for onset of liquid carry-over in the form of annular/mist flow). With appropriate modifications, GLCCs can be used for wet gas (high gas liquid ratio, GLR) applications, characterized by higher gas velocities, to knock out the liquid droplets from the gas core. The objectives of this study are to design a novel GLCC capable of separating liquid from a wet gas stream; conduct experimental investigations to evaluate the GLCC performance improvement in terms of operational envelope for liquid carry-over; and, quantify the liquid extraction from the gas stream. GLCC design considerations/guidelines for wet gas application are also provided based on the experimental studies at low pressures. This investigation extends the capabilities of compact separators for wet gas applications for insitu gas volume fraction (GVF) greater than 95%.

Soil Cleanup by In-Situ Aeration. XX. Mass Transport of Volatile Organics in Wet Activated Carbon

Abstract A mathematical model for the adsorption of volatile organic compounds (VOCs) from wet gas streams by granular activated carbon columns is developed, and modeling results are discussed. Capillary condensation of water in the carbon pores is found to have a very damaging effect on the rate of VOC adsorption, since diffusion rates of VOCs into the pores are greatly reduced. Implications of the results for the operation of soil vapor extraction systems for the remediation of hazardous waste sites are discussed, and suggestions are made on how to deal with the problem.