Valve Tray Research Articles

Hydrodynamics and wet pressure drop model based on flow regimes of the novel Flow-Divided Baffle-Bridge Tray

This study introduces the Flow-Divided Baffle-Bridge Tray (FDBBT), an innovative tray design featuring hole-bridge structures at the caps’ base for pre-distribution of gas and liquid, and stepped baffles configuration at the caps’ top to minimize entrainment. The pressure drop, weep and entrainment of FDBBT were evaluated in a Φ796 mm experimental setup. Compared to the sieve tray and Glitsch V-1 valve tray, FDBBT demonstrated lower pressure drops and significantly reduced entrainment, suggesting a higher operational ceiling. Furthermore, a specialized single-cap experimental apparatus was designed to assess the lifted liquid rate and uncover gas-liquid flow regimes within the cap, namely churn flow, free-surface flow, and periodic-free-surface flow. Employing data from the single-cap experiments, complemented by CFD-assisted analysis, FDBBT's pressure drop model was established and then validated by the Φ796 mm experiments, with most deviations falling within a 5 % threshold.

Correction to “Open Balance Point and Dry Pressure Drop of a Rectangular Float Valve Tray: Experiment and CFD Simulation”

Correction to “Open Balance Point and Dry Pressure Drop of a Rectangular Float Valve Tray: Experiment and CFD Simulation”

Open Balance Point and Dry Pressure Drop of a Rectangular Float Valve Tray: Experiment and CFD Simulation

Open Balance Point and Dry Pressure Drop of a Rectangular Float Valve Tray: Experiment and CFD Simulation

CFD dynamic mesh-based simulation and performance investigation of combined guided float valve tray

This paper simulated the combined guided float valve tray based on the computational fluid dynamics (CFD) dynamic mesh technique. The motion equation of the float valve under force was compiled into the user-defined function (UDF) to calculate and finally obtained the float valve opening height under distinct working conditions. Based on this, adjustments were applied to the float valve opening height of the geometric model and were validated. The clear liquid heights obtained were closer to calculated values than when the float valve fully opened under identical working conditions. The errors between the simulated values and two correlative calculated values reduced from 10.68% and 19.01% to 7.35% and 15.55%, indicating the simulation results are reliable. Furthermore, this paper quantified the liquid phase reverse flow and used the reverse flow area fraction to measure the liquid back-mixing degree. The simulation results of six tray structures were compared, and it was verified that specific deflection angles of trapezoidal float valves could effectively reduce the back-mixing degree. Notably, 10° is the optimum float valve deflection angle of the tray, which can reduce the average reverse flow area fraction from 40.4% to 33.1%, with a reduced rate of 18%.

Hydraulic investigations of standard and high performance trays in a DN1200 column

In the course of a more fluctuating power supply due to renewable energy sources, the need for tray columns with flexible operability increases. Accordingly, further research is required to better predict the behavior at load limits – especially for fixed and float valve trays. Within this work, the hydraulic behavior of numerous valve tray configurations was investigated employing a 1.2 m diameter gas/liquid (air/water) pilot test column. Fixed and float valve tray performance has been validated using sieve trays as a reference, which have already been extensively studied in the literature. In order to obtain significant data, weeping and entrainment limits in particular, as well as froth height and pressure drop, were measured quantitatively in the experiments. By varying the geometry parameters, numerous different cases were investigated. Based on all the data obtained, reliable statements can be made about the validity and applicability of calculation models known from the literature.

CFD Simulation and Optimal Design of a New Parabolic–Shaped Guided Valve Tray

A new parabolic–shaped guided valve tray is proposed. The gas–liquid two–phase flow of parabolic and conventional rectangular guided valve trays is simulated using the computational fluid dynamics (CFD) method. The clear liquid height on the tray was predicted for different combinations of the superficial gas velocity, liquid flow intensity and weir height. The predicted values were in good agreement with the calculated ones. The parabolic–shaped guided valve tray has a more uniform flow form by comparing the gas–liquid two–phase flow behavior of parabolic and rectangular guided valve trays: the liquid level difference is slight, the guiding effect is strong, and the re–mixing phenomenon is improved. Further modeling and simulations were conducted for nine parabolic–shaped guided valve trays of different function expressions. The optimum valve structure is the parabolic–shaped guided valve of the a–value at 0.075 and the t–value at 26.

Improvement of Fixed Valve Trays

Improvement of Fixed Valve Trays

Progressive Schemes and Methods of Obtaining Rectified Alcohol Applied in Russia and Abroad

The main quantity of the produced ethyl alcohol is consumed by the food industry as a basis for the manufacture of alcoholic beverages, pharmaceuticals and other alcohol-containing products. In addition to food production, ethyl alcohol is widely used in medicine, perfumery, and other industries. The actual problem of alcohol production is finding ways to reduce the cost of raw materials and energy resources but still getting the world quality standard of alcohol. The best solution to the problem is to improve the technological schemes of rectification plants. For this, information was updated on modern schemes and methods for obtaining rectified alcohol. During the research, and information search was carried out in Russian and English language literary sources. A comparative analysis of books, manuals and articles on this topic was carried out, as well as the GOSTs requirements for rectification columns over the past few years were studied. The main components of rectification units were considered: contact devices (types of plate and packed devices) and rectification columns (applied pressure: atmospheric, vacuum, under a certain pressure; and their total number).Progressive schemes used in modern alcohol production in Russia and abroad (Ukraine, USA, France, Finland) were considered. Based on the received data, the following conclusions were formulated: the most effective types of contact devices are sieve and valve trays, among the packing there are Raschig rings, a promising type of columns is disc-type, the most popular scheme for the operation of a rectification plant is a combination of work under pressure and vacuum.

Analysis of Performance and Updating of a Rectifying Column for Hydrofined Diesel Fuel Stabilization

Investigation and mathematical modeling of the performance of a diesel fuel stabilizing rectification column were carried out. An analysis of the calculation results showed that the liquid phase may fall onto the valve trays of the stripping section of the column, upon which hydrogen sulfide may get into the desired product. High-quality diesel fuel can be obtained without feeding steam (stripping agent) into the column by calculated blocking of a part of the trapezoid valves on the trays.

Hydrodynamics and mass transfer performance analysis of flow-guided trapezoid spray packing tray

Distillation is the most common separation technology utilized in the petroleum and chemistry industries. Due to the wide usage of the distillation column, even a small improvement in performance may result in significant energy cost savings. Aiming to improve the hydrodynamics and mass transfer performance, the flow-guided trapezoid spray-packing tray (FTS-PT) was designed by combining flow-guided holes and trapezoidal caps with structured packing. And the experimental measurements of the FTS-PT, including pressure drop, clear liquid height, weeping, entrainment, and tray efficiency, were conducted in a 500 mm diameter plexiglass column with the air-water-oxygen system. Moreover, the performance of the FTS-PT was compared with that of new vertical sieve tray (New VST) and F1 valve tray. The results show that FTS-PT has a significant advantage in pressure drop, entrainment, and capacity. Furthermore, the calculation model of the pressure drop was derived and used for the FTS-PT with a relative deviation of less than 5%.

Optimizing Study of Some Factors That Influence the Performance of Valve Trays in Crude Oil Distillation Towers

Valve trays play an important role in the productivity of crude oil distillation towers. The performance efficiency of these valves depends on their erosion-corrosion and fouling corrosion. In this research, NiCrAlY powder with constituents of different ratios of Molybdenum (Mo) was used as a deposited coating layer on the surface of 446 stainless steel. The scanning electron microscope and XRD were used to study the microstructure of the coating layer. Microhardness test was carried out to evaluate coating layer hardness. Erosion – corrosion test was performed to evaluate the performance of the coating layer under an aggressive medium of glass sand and a mixture of sulphuric acid and hydrochloric acid. Contact angle test was carried out to evaluate the contact angle of coated and uncoated samples. Taguchi / ANOVA technique was used to tabulate data and to optimize the results. The results showed that the coating layer containing 4% Mo exhibit high erosion-corrosion resistance and good contact angle, which improving the fouling resistance of the samples under working conditions.

Preventing of flooding phenomena on vacuum distillation trays column via controlling coking value factor

The occurrence of flooding phenomena (FP) on the vacuum distillation trays column (VDTC) is investigated on a refinery in the middle region of Iran. Accumulation of coke sediment that is occasionally observed in refinery processing using coal tar (CT) feeding is the main reason of the FP on VDTC. This usually occurs at the down-comer areas and the seal pans of the column. Quinolone insoluble (QI) and toluene insoluble (TI) parameters, two routine methods used to measure coke containing sediments, are employed to determine probable critical areas of FP at the down-comers and the seal pans of CT feed in this study. Analyzing the obtained results of QI and TI tests demonstrated that FP at the column is directly related to the quality of CT feeding. For instance, when the QI of the inlet CT in battery 1 increases from 0.56%W in the first sample to 6.5%W in the 25th sample, the vacuum pressure at the top of the distillation column is reduced from − 230 mbar to − 420 mbar. To prevent sediment accumulation of coke and the occurrence of FP, the CT feeds are centrifuged to reduce coke sedimentation at the down-comer areas and the seal pans of VDTC. Moreover, the seal pan trays are replaced by normal ones and all moveable valves with 25 mm diameter on trays 15 and higher in the column, where coke sediment accumulation is observed the most, are modified by installing wider fixed valve (40 mm diameter) trays.

Experimental study and modeling of weeping rate in rectangular large‐scale valve trays

AbstractWeeping is an important hydraulic parameter that needs to be considered for valve trays and for calculations in the distillation field. Therefore, the accurate prediction of weep rate is crucial for the optimal design of valve trays. First, the effects of gas and liquid loads and weir height on weep rate, tray pressure drop, and actual bubbling area were studied in a 1.5 m × 0.61 m cold simulator. Second, the weep modes on the valve tray were analyzed in detail. A theoretical model was then derived to calculate weeping. The model showed a clear relationship between the weep rate and the fractional bubbling area. The experimental data showed that the weir height substantially affected the orifice coefficient of the liquid passing through the valve. Finally, the relation between weir height and orifice coefficient was obtained by fitting the experimental data. The agreements were good, and the maximum deviations were approximately 25%.

Improving Oxidation Resistance Wear Properties of Valves Trays Used in Oil Distillation Towers

Valve trays play an important role in the refinery crude oil distillation process. Valve trays are covered by lift able caps. The lifting cap positions vapor to flow horizontally into the liquid which providing better vapor/liquid contact and better separation at each tray. Corrosion and wear resistance are the most important properties should be found in the valve trays and caps. This research deals with increasing corrosion and wear resistance of valve trays and caps using thermal spray technique. (Ni Al Cr) powder was used to apply coating layer on the substrate surface. Some mechanical properties are evaluated for the coating layer. Oxidation test was performed using oxidation system. Data and results revealed that the coating layer with the thickness of 100 µm has slightly resistance against oxidation, while the thickness of 200 µm has excellent oxidation resistance and good peeling resistance. Thickness of 300 µm has excellent oxidation resistance but has poor peeling resistance.

Analysis of entrained liquid by use of optical measurement technology

A novel approach to investigate entrainment with aid of a photographic probe enables inline analysis of entrained liquid above column internals at different radial and axial positions. Latest CMOS camera technology allows precise assessment of form and size of droplets at high image qualities and small outer dimensions. A DN 450 cold flow test rig equipped with sieve and fixed valve trays generates droplets over a broad range of gas (1.0–2.75 Pa) and liquid (1.0–20m3/mh) flows. Results show a strong dependence of droplet sizes on many operation parameters of the column. An increased gas factor of 1.0 Pa above the sieve tray reduces the share of droplets below 500μm from 87% to 18%. Sieve tray experiments show a reduction of droplet size with higher liquid loads. Measurements at greater heights above the fixed valve tray reveal a decrease of the most frequent droplet size (25–50μm) by factor 2.9. Closer to the column wall, the fixed valve entrains smaller droplets. An extrapolation from local to integral entrainment rates for comparison with the conservative capture tray method achieves satisfactory agreement. Capability of models from literature to cope with the available data are discussed.

Quantification of Entrainment Using an Optical Inline Probe

AbstractIn distillation and absorption processes, entrainment above trays or packings reduces stage and column efficiency. A modified version of the optical multimode online probe enables a seminal insight and, thus, quantification of entrained droplets on various axial and radial positions. A purging mechanism inhibits precipitation of droplets on the front lenses, while telecentric optics and illumination provide distance‐independent and precise imaging of entrained droplets between two valve trays. Experiments were performed in a DN 450 cold flow (air‐water) test rig. The results were compared with noninvasive phase Doppler anemometry data.

Study of Clear Liquid Height and Dry Pressure Drop Models for Valve Trays

In this work, literature correlations developed for tray clear liquid height and dry pressure drop are analysed and compared with FRI published data. Four valve trays measured and published by FRI are used in the data analysis. For clear liquid height models, the fundamental Colwell (1979) correlation based on Francis’s equation was analysed. The Bennett (1983) model based on air-water data, the Hofhuis and Zuiderweg (1979) model based on spray regime and mixed-froth regime, the Dhulesia (1984) model based on V1 valve and air-water data, the Brambilla (1969) model based on air-water data, and the Glitsch (2013) from Koch-Glitsch Bulletin 4900 were also analysed and compared with each other.The dry tray pressure drop can be modelled by two ways. For the fixed valve tray and the sieve tray, an orifice type equation is used. The major difference between different researchers is the correlation for orifice constant. For the movable valve/float valve tray, the pressure drop curve is divided into three regions by the valve positions: fully closed region, partially open region, and fully open region. These three regions are determined by the closed balance point (CBP) and the open balance point (OBP). In this work, five literature models were analysed and compared with FRI data. Two of them are based on fixed valve tray or sieve tray (Smith and Van Winkle, Stichlmair), while the other three are based on movable valve tray (Glitsch, Klein, Bolles).In conclusion, this work studied the two hydraulic parameters for valve trays by analysing literature correlations with FRI measured data. Results show that most of the literature correlations under-predict the clear liquid height for the above four trays. Except for the models based on Francis’s theory, the literature correlations cannot predict the trend of the clear liquid height with the bubbling velocity. For the dry tray pressure drop, the three-region models give better prediction than orifice type models for the four valves in FRI database. This work provided a new thought and pathway for future model development.

Hydrodynamics performance and tray efficiency analysis of the novel vertical spray packing tray

Abstract Column setup has been widely utilized in the petroleum and chemistry industries. However, with the fast progress of industries and the increasingly serious energy shortage, designing a new column setup with better performance and higher capacity becomes more urgent. In order to improve column's capacity and expand operating condition, a new type of column tray named novel vertical spray packing (NVSP) tray was designed and experimented. The performances of the novel tray, including pressure drop, weeping, entrainment and tray efficiency, were tested in a plexiglass column. In addition, performances of the novel tray were compared with that of the sieve tray and the Glitsch V1 valve tray. Based on the experiment data, the mathematical correlations of pressure drop, weeping and entrainment for the novel tray were established by regression analysis method. A fundamental model of dry pressure drop of the novel tray was promoted at the form of sum mode. The results indicate that the novel tray has wider operating condition and better performance.

Development of a technique of the automated construction of 3D models of standard mass transfer trays

The main elements of most mass-transfer columns of industrial enterprises are contact trays which are formed by various details inside the apparatus. The dimensions of the details are standardized and regulated by regulatory documents. under modern conditions of equipment designing it is necessary to develop three-dimensional model of typical assembly units, that is a very time-consuming task. The article considers the way to improve the design efficiency by automation of the process of standard mass-transfer valve tray model development in Kompas 3D system with MySQL application.

CFD simulation of sieve-fixed valve tray hydrodynamics

In this work, the sieve-fixed valve (SFV) tray was designed by adding flow-guiding and sieve holes on the valve caps of the original trapezoid valve (OTV). A computational fluid dynamics (CFD) model of three-dimensional two-phase flow was developed to describe the flow structure of SFV tray. Based on the experimental clear liquid height, the modified correlation of Bennett was adopted for liquid–gas interaction and the ga–liquid momentum transfer term MGL was also obtained. To demonstrate the function of flow-guiding hole and sieve hole, the hydrodynamics of the OTV and SFV trays including pressure drop, weeping, entrainment and clear liquid height were experimented and compared. What’s more, local information such as velocity profile and flow field around the valves were simulated. CFD results showed that the new valve tray with flow-guiding holes was capable of promoting liquid flow and homogenizing liquid flow. This study proved that CFD research can test modification of devices, and provide information which could not be obtained by experiment. The CFD method tends to be a necessary part for designing and modifying new distillation internals.