High velocity acid mists collection.

Reduction Of Glycol Loss From Gas Dehydration Unit At Offshore Platform in Bombay Offshore - A Case Study. Abstract Glycol dehydration is most common liquid dessicant for removing water from natural gas. Under normal operating conditions, make up glycol rate is about 16 litres/MMSCM (0.12 gal/MMSCF) of gas treated. In the present case make-up glycol consumption exceeded four times normal value at gas dehydration unit (GDU) at one of the offshore platform in Bombay High. Chemical analysis of circulated glycol was carried out. The plant operating parameters were simulated. Sensitivity analysis of important process parameters was done to evaluate their effect on plant performance and operating parameters with a view to reduce glycol loss while achieving dehydration efficiency. Chemical analysis of glycol has shown presence of contaminants. The analysis of operating parameters have shown glycol foaming tendency, higher pressure in glycol reboiler and high stripping gas rate. Based upon analysis and simulation studies, troubleshooting was carried out which has resulted in significant saving in makeup glycol consumption. Introduction ACG is one of the process platform in Bombay High which receives wet gas from oil process platform for compression, dehydration and export. It is processing about 4 MMSCMD of gas. The inlet gas is compressed from 7 kg/cm2g to 90 kg/cm2g in three stage compressors. The compressed gas is dehydrated using Triethylene Glycol (TEG) in two identical parallel trains of gas dehydration units (GDU) to meet pipeline transportation specification with maximum of 112 kg/MMSCM (7lb/MMSCF) water vapor in gas. This gas is transported to land base through the trunkline. The process schematic of the gas dehydration unit (GDU) is given in Fig. 1. It consists of a contactor tower having eight bubble cap trays for absorption of water vapor from gas by using TEG, and a TEG regeneration unit. The operating data of one of the train is given in table 1. Normal make up glycol rate for such types of gas dehydration units is about 16 litres/MMSCM. But in this plant glycol consumption was about 70 litres/MMSCM resulting in a significant loss of revenue during plant operation. Many workers mention normal glycol consumption rate of 13.4 litre/MMSCM (0.1 gal/MMSCF) of gas. In another analysis Ghoshal indicated equilibrium glycol loss of 17.4 to 22.7 litre/MMSCM (0.13 to 0.15 gal/MMSCF) at 54.4 C (130 F) gas inlet temperature. In similar work, Weininger recommended to carry out an audit of the unit if glycol consumption exceeds 7.2 - 28.6 litre/MMSCM (0.5-2 lb/MMSCF) of gas. All these parameters therefore indicated that present plant of Bombay offshore requires a thorough audit of GDU to identity the causes of glycol loss and prevent the same. Glycol Loss Audit Glycol losses from GDU are grouped into three categories–Vaporisation–Carryover–Mechanical Vaporisation loss takes place both in glycol contactor as well as in glycol still of regenerator. The equilibrium vaporisation loss from contactor is normally 5% of normal loss and is primarily due to higher gas inlet temperature. The vaporisation loss in glycol still is due to higher still temperature and high stripping gas rate. The carry over loss in absorber is generally due to foaming, high gas velocity and inadequate mist eliminator at gas outlet. The carryover loss in glycol still is due to high stripping gas velocity and foaming in still column. P. 549

Effects of nitrogen dioxide and its acid mist on reactive oxygen species production and antioxidant enzyme activity in Arabidopsis plants

Acid mist inhibitor is an effective additive for suppressing the generation of acid mist during electrowinning process. However, the traditional acid mist inhibitor has a low current efficiency, leading to high energy consumption. Thus, novel acid mist inhibitors are crucial for the development of the electrowinning industry. In this paper, three new acid mist inhibitors (Famigo® FS-101, Famigo® FS-301, and Famigo® FS-401) are used in zinc electrowinning process, while the mechanism of action in suppressing the generation of acid mist is characterized by the volume of bubble attached on the cathode surface and surface tension. The impacts of the concentration of the acid mist inhibitors on the bath voltage, current efficiency, power consumption, and electrochemical properties, as well as the enhancement mechanism on the current efficiency, are studied. The obtained results demonstrate that an adequate concentration of Famigo®FS-101, Famigo®FS-301, and Famigo®FS-401 allows to increase the cathode current efficiency and decrease the energy consumption, from 3219 kWh t−1 in zinc electrolyzer to 2948 kWh t−1, 3090 kWh t−1, and 2884 kWh t−1 using a concentration of 5 mg l−1 of Famigo®FS-101, Famigo®FS-301, and Famigo®FS-401, respectively. The proposed inhibitors have high acid mist inhibition efficiency and current efficiency in the zinc electrowinning process. Furthermore, if engineered, they may contribute to the development of the electroposition industry.

Some features of the operation of a dense bed at high gas velocities are examined, together with the conditions of suspension of the charge in a furnace. The maximum permissible gas velocities in the bed are obtained. The flow friction is determined for loose material in the moving and stationary beds.

1. The hydrodynamics and mass transfer in a ring-shaped jet plate of 300 mm diameter have been studied in a pilot unit in which CO2 was desorbed from water with air, while the gas velocity was varied from 0.6 to 3.5 m/sec. 2. The plate has a low interphase resistance at high gas velocities. The measured values of the plate efficiency and the mass transfer coefficient are high, and nearly constant over a broad range of gas velocities at various liquid velocities. No entrainment of jets occurs at high gas velocities. 3. Our results suggest that the ring-shaped jet plate may be recommended for use in tests in oil refinery columns where a high output is required and the hydraulic resistance of the plate has no practical importance.

Experiments were performed to investigate the gas–liquid interfacial area and the liquid-phase mass transfer coefficient of a two-phase dispersion on sieve plates with hole diameters of 4–12 mm and with free areas of 5.5–50.4% without downcomer. Operation was carried out at high gas velocities using cobalt-catalyzed oxidation of aqueous sodium sulfite solution with air.The two-phase dispersion showed froth regime and transition regime, which is called partially developed spray regimes/mixed froth regimes, depending on the gas velocities. The gas–liquid interfacial area of the two-phase dispersion in the froth regime is influenced by the free area of the plate, whereas no effect of free area is found in the transition regime. The correlations of interfacial area for each regime are given on the basis of the correlation obtained by Zuiderweg under a gas–liquid cross-current condition. Empirical equations for the Sherwood number based on liquid depth are obtained. Using the results of the interfacial area and the mass transfer coefficient, the mass transfer volumetric coefficient can be predicted.

The findings of spectroscopic observations of several off-nuclear regions in NGC 1275 are studied with a view to their implications for hypotheses as to high-velocity emissions. The observations indicate that the high velocity gas does not exhibit a smooth gradient, but instead appears disrupted. Absorption is found from the high velocity system in the Na I D lines, and the stellar absorption noted from the high-velocity system in the Ca II 8498 A line is consistent with both an early-type stellar population and the difficulty of subtracting bright night sky emission lines in the Ca II triplet region. Either the emission line velocities do not represent motion governed by the internal dynamics of the galaxy, or the galaxy is of very eccentric H I content, size, and structure. 32 refs.

The calculations of friction pressure drop is the most complicated in multiphase flow. Understanding of the friction pressure drop in pipes are of great importance for many industry problems. The existing friction pressure drop models are generally based on low gas and liquid velocities in horizontal and vertical pipes. In this paper, a two-phase flow experiment in inclined pipe was performed. We report the effect of superficial gas and liquid velocities on friction pressure drop, the results indicate that the pressure drop increases with the increase in superficial gas velocity and superficial liquid velocity. According to the experimental analysis and assuming that the fluid in contact with the pipe wall at high velocity is in a liquid phase, we developed a new friction pressure drop model of different flow pattern. This model based on the correlation between the fraction factor and the superficial gas and superficial liquid Reynold numbers. Compared with the previous models, the predictive performance of the present model is good and remains basically stable.

view Abstract Citations (18) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High-Velocity Formaldehyde Absorption within 30 of the Galactic Nucleus Pauls, T. ; Johnston, K. J. ; Wilson, T. L. ; Marr, J. M. ; Rudolph, A. Abstract VLA observations of the (110 - 111) line of H2CO in absorption within 30 arcsec of the Galactic center point source Sagittarius A* with a resolution of 20.6 x 9.5 arcsec at PA of 4 deg, and an rms noise of 3.5 m Jy/beam are reported. A number of baseline subtractions are performed using different velocity intervals to define the continuum level. In all cases the absorption is definitely present. At positions offset +/- 1 arcmin in latitude from SGR A* there is no evidence for absorption at high velocities. Thus, the high-velocity gas may be close to, but is not coincident with, SGR A*. Taken together with observations of HCO(+), HCN, and forbidden O I, there are now several pieces of evidence indicating that the central cavity at the Galactic center contains a mixture of neutral and ionized gas. Publication: The Astrophysical Journal Pub Date: January 1993 DOI: 10.1086/186710 Bibcode: 1993ApJ...403L..13P Keywords: Absorption Spectra; Formaldehyde; Galactic Nuclei; Milky Way Galaxy; Astronomical Spectroscopy; Forbidden Bands; Ionized Gases; Point Sources; Very Large Array (Vla); Astrophysics; GALAXY: CENTER; GALAXIES: NUCLEI; ISM: MOLECULES full text sources ADS | data products SIMBAD (5)

We analyse absorption characteristics and physical conditions of extraplanar intermediate- and high-velocity gas to study the distribution of the neutral and weakly ionised Milky Way halo gas and its relevance for the evolution of the Milky Way and other spiral galaxies. We combine optical absorption line measurements of CaII/NaI and 21 cm emission line observations of HI along 103 extragalactic lines of sight towards quasars (QSOs) and active galactic nuclei (AGN). The archival optical spectra were obtained with UVES at the ESO VLT, while the 21 cm HI observations were carried out using the 100-m radio telescope at Effelsberg. The analysis of the UVES spectra shows that single and multi-component CaII/NaI absorbers at intermediate and high velocities are present in about 35% of the sight lines, indicating the presence of neutral extraplanar gas structures. In some cases the CaII/NaI absorption is connected with HI intermediate- or high-velocity gas, while other absorbers show no associated HI emission. Our study suggests that the Milky Way halo is filled with a large number of neutral gaseous structures whose high column density tail represents the population of common HI high-velocity clouds seen in 21 cm surveys. The CaII column density distribution follows a power-law which is comparable to the distribution found for intervening metal-line systems toward QSOs. Many of the statistical and physical properties of the CaII absorbers resemble those of strong MgII absorbing systems observed in the circumgalactic environment of other galaxies, suggesting that both absorber populations may be closely related.

Influence of pressure and fluidization velocity on the hydrodynamics of a fluidized bed containing horizontal tubes

PULMONARY HYPERTENSION DUE TO OBSTRUCTION OF INTRAPULMONARY VEINS

Bubbling fluidized beds with horizontal solids crossflow can be broadly grouped according to function: 1) those designed for solids looping, as in indirect pyrolysis or gasification, and chemical or calcium looping; and 2) those employed in high-throughput solids processing, such as drying, iron ore reduction, and pharmaceutical manufacturing. Despite their widespread industrial application and the growing demand for their use in new process designs, there remains a lack of a detailed understanding of the flow characteristics in fluidized beds with horizontal solids throughput. This knowledge gap represents a major challenge for optimizing reactor design and advancing industrial implementation.This thesis aims to develop a mechanistic understanding of how forced horizontal convection of solids in a bubbling fluidized bed influences the solids flow characteristics. The main research objectives are to: (i) assess experimental methods for quantifying the solids circulation rate; (ii) evaluate the efficiencies of different mechanisms to induce horizontal convection of solids; (iii) characterize bed solids transport—specifically, the interrelated effects of solids convection and dispersion—and the resulting fluidization quality; (iv) investigate how the solids crossflow influences overall flow structures; (v) examine the influences of frictional losses on bed solids flow, including the rheological properties of the dense suspension; and (vi) explore how the solids crossflow affects the mixing of a secondary solids phase consisting of large, light particles.Experiments were conducted in a cold-flow model that comprised a closed-loop system in which solids were circulated horizontally via a solids-conveying module. The apparatus was designed and operated according to Glicksman’s simplified scaling laws. In this cold model, fine bronze particles are fluidized with ambient air to fluid-dynamically resemble conditions representative of industrial-scale thermochemical fuel conversion applications. The industrial unit being modeled features a bed channel with a cross-sectional width of 0.92 m and a transport loop length of 10.35 m, in which coarse, sand-like (Geldart B-type) particles are fluidized with flue gas at approximately 800°C.Four measurement methods for quantifying solids circulation were evaluated—namely, integral mass accumulation, differential mass accumulation, thermal tracing, and magnetic solids tracing—with the latter proving to be the most precise and robust. Using this method, five solids-conveying configurations based on different fluid-dynamical mechanisms were tested: (a) free solids splashing, which relies on bubble bursts to eject particles; (b) confined solids splashing, whereby turbulent fluidization creates particle transport that is dominated by eddies and bubble buoyancy; (c) slugging, whereby gas slugs drive particle movement in vertical ducts; (d) solids entrainment, which is achieved by elutriation at high gas velocities; and (e) directed gas injection, which imparts lateral momentum through angled nozzles. Conveying solids under a controlled bubbling fluidization regime was found to be the most efficient configuration for promoting horizontal transport of solids in the system.The horizontal solids flow established in the channel was evaluated under various operational conditions using a combination of experimental and modeling approaches, ranging from reduced-order descriptions to Eulerian–Eulerian computational fluid dynamics (CFD) simulations. A positive linear relationship was observed between the solids dispersion coefficient and the mean solids velocity, both evaluated in the streamwise direction. This was further explained by the CFD simulations, which indicated that at low crossflow rates, the solids flow organizes into coherent, counter-rotating vortices along the bubble paths. In contrast, at high crossflow rates, these structures are disrupted, resulting in less streamlined (stronger mixing) and more elongated (longer characteristic lengths) flow patterns. In addition, microscale dispersion was found to be dominated by bubble- and eddy-induced mixing, rather than by random particle motion or collisions. Rheological analysis revealed that the bed exhibits shear-thinning behavior and that single-phase models for non-circular open-flow channels underestimate the influence of geometry on gas-solids flows.Analysis of the transport behavior of large, light particles added to the bed as a lean phase showed that, similar to bulk solids, a positive correlation exists between dispersion and convection, with sensitivity strongly dependent on the degree of fluidization. The dispersion of the lean particles was greater than that of the bulk solids; it remained at a similar level for both low and high fluidization velocities. However, compared to the bulk solids, the lean particles were transported at lower convection velocities under high fluidization levels. In contrast, at low fluidization levels, the particles formed a layer above the dense bed and were conveyed in a plug-like manner, exhibiting much higher horizontal velocities than the bulk solids.

The Reedijk-1 gas well was completed in 1992 with 3 ½" Carbon Steel (CS) tubing and taken into production early 2003 with a capacity of 1.8 mln Nm³/d. Due to the CO2 content, continuous corrosion inhibition was required. However as a result of operational problems it took about 9 months before injection was established. In August 2004 it was observed that the annulus injection pressure increased slowly towards the tubing head pressure and finally became equal. By closing the flapper valve and releasing some pressure of the tubing, it was assessed that the communication should take place above the subsurface safety valve. A downhole video camera run was carried out and identified the leak 1.8 m below the top of the tubing hanger. The camera also revealed that pipe bodies were still in good shape but the couplings showed severe pitting. Subsequently, straddling off the leaking coupling minimized gas production deferment. The well could normally be produced until it was worked over to 5" Chromium 13 (Cr13) tubing. From this case history it can be learned that: In high rate gas wells understanding the film persistency of the chemical corrosion inhibitor is important as removal of inhibitor films is a possibility due to the high velocities thereby leaving this part of the tubing unprotected. This is especially the case at subsurface safety valve (SSSV) depth as a result of the restricted diameter.The application of chemical corrosion inhibition in downhole situations may not manage corrosion when pitting corrosion has been initiated.Alternative solutions to corrosion management need to be sought. Improved technologies that enable increased inhibitor availability, improved inhibitor chemistry's demonstrating high persistency at high gas velocities. Application techniques such a batch dumping of corrosion inhibitor into the well with high persistency chemicals are being tried as alternatives.

High velocity gas in S241 and IRAS 19529+2704