Structured packing. Examples of values from different packing types are presented. RVT Process Equipment GmbH provides a broad range of innovative and conventional structured packings in both metallic and thermoplastic Nov 8, 2023 · Abstract It is known that nonuniform irrigation leads to a significant reduction in the productivity of column and a noticeable decrease in the quality of separation of mixtures. MellapakPlus is a capacity enhanced structured packing. Both random-packed towers and structured-packed towers require liquid distributors at the top of the column and packing support plates at the bottom of the column. efficiency, capacity, and pressure drop) are described and examples given. The individual layers are produced from special metal gauze that maximizes the capillary effect. Styrene Manufacturing. May 8, 1996 · This is the second part of a two-part paper dealing with the fluid mechanics and mass transfer in structured packings for distillation column service. Apr 1, 2023 · For structured packing applications, the near atmospheric and vacuum hydrocarbon test data are especially important to the industry. Y. Original demisters installed in a large demister tower can not blocks the mini liquid droplets into the downstream compressor. MACH Engineering manufactures X and Y structured packing from 304 and 316 stainless steel. Characterisation of packings can thereby be concentrated within one single diagram. , iron sulfide). A special high-performance structured packing, PACK-13C, with the surface area high as 1135 m2 m−3 was developed, and the first stable isotope 13C pilot-scale plant using structured size for a particular family (brand) of structured packing used in the same service. The investigations undertaken allow extrapolation and therefore performance prediction of further developments. Packings are divided into structured and unstructured. . Plastic structured packing, wire gauze and plate type, is specialized designed for high temperature and corrosive absorption and scrubber applications. This type of packing is used for a wide range of applications in both industrial and environmental processes, including distillation, absorption, scrubbing Mar 1, 2010 · Abstract. Jan 1, 2003 · Chemical Engineering Research and Design. The material thickness and the grid height are adjusted based on the column diameter, packing height and the liquid hold-up. Large flexibility, and scale effect is not obvious. It is widely used and more and more popular since it is developed. As an example, a structured packing product brochure [ 4] lists characteristic HETP values for two families of structured packing. We can supply structured packing, including plate packing or wire gauze packings in metallic, ceramic and plastic materials for high filtering efficiency. , 125 m2/m3) provides high capac-ity and low efficiency; a column with this packing can be smaller in diameter, but to achieve the required number of stages must be taller than a column whose packing has a much higher surface area (e. Conversely, use structured packing in applications that require high capacity and efficiency. Packing Design Fundamentals One of the fundamental characteristics of structured packings is that they have their greatest advantage in high vapor rate and low liquid rate applications. Oct 3, 2023 · However, structured packings are more efficient and will afford a shorter column. The choice of material depends on the Sep 1, 2017 · The structured packing Zulser 350Y was installed in the distillation column with the diameter of 0. A high-surface-area packing provides less Structured packings are characterized by high performance and a flexible application concept. Jan 1, 2014 · The metal gauze packing BX and CY from Sulzer was the first structured packing on the market. harsh environment structured packing. This type of tower packing is composed of materials such as metals and plastic, sometimes referred to as knitted mesh. Characterization of High-Performance Structured Packing. Wider operation range than with trays. Mechanistic Model for Structured-Packing-Containing Columns: Irrigated Pressure Drop, Liquid Holdup, and Packing Fractional Wetted Area. random packing necessitates different strategies. Capabilities. The neighbor packing pieces are assembled oppositely. They offer high separation performances, high throughputs, extensive working ranges and low pressure drops. Structured packing with a corrugation angle of 60° has not been marketed. Because trays would be working at high percent flooding, Gempak structured packing is condensed (Figures 9-56A-D). The first part elucidated pressure drop, flooding, and liquid holdup. When high capacity is a necessity, the intricate internal structure of structured packing allows for a high surface area that translates into extremely high capacity. 5 mm Advantage of Metal Structured Packing. The corrugation amplitude of the sheets steers the number of sheets per block and by this the supplied surface area of the packing. The mesh structure is a ring-shaped mesh surrounded by triangular meshes, which is stable in structure and G-sPAC is an industry standard structured packing available in a variety of sizes. May 26, 2023 · Structured packing costs can range from $45 per cubic foot to over $400 per cubic foot. 8. A structured packing with a low surface area (e. The corrugation angle is measured with respect to the vertical. The resulting file was imported into a three-dimensional imaging program and then copied, translated, and rotated to create a stack of three packing elements. In this study, the complex hydrodynamics characteristics of structured sinusoidal corrugated sheets packings were investigated by 2D liquid film model and 3D Representative Element Unit model. Perforated or imperforated surface. This packing is commonly available with crimp angle of 45° and 60 °, referred to as X type and Y type respectively. Sulzer offers various types of structured packings for different separation tasks, such as Mellapak, MellapakPlus, MellapakCC, AYPlus, BX, CY, and Mellacarbon. The mesh structure is a ring-shaped mesh surrounded by triangular meshes, which is stable in structure and can May 1, 2023 · In industrial use, a scale-up approach is commonly used to determine the required height of a distillation column with structured packings. 1mm (this results in a bulk weight of about There is detailed description of structured packing tower features: Streamline gas feed distributor features: The flow channel cross section of the gas-liquid mixture flow gradually expand, no mutation part, so the loss is less, air resistance. The PACK-1300XY constructed 12 sheets Structured Packing – High Performance for Separation & Distillation. Structured metal packing comes in standardized blocks, making it straightforward to install through a manway. The design is intended to ultimately produce a large surface area Nov 2, 2021 · Structured packing is an important equipment and has wide applications in chemical separation process. The model was applied to determine The RVT Metal Packing (RMP) is available in several designs: Smooth or textured surface. Similar to the metal packings, they are available in GSP-1: Mellagrid structured packing is usually used in fouling environment. This packing has several attractive properties, such as high voidage ( ε =94%) and high effective area ( a =420 m 2 m −3 ). Grid packing (wooden slats packing) is a prototype of most modern types of structured packing (Fig. PTFE Structured Packing typically consist of thin corrugated PTFE sheets arranged in a way that they force fluids to take complicated paths through the column, thereby creating a large surface area for Careful examination of the correlations for the effective interfacial area of the structured packed columns in the literature reveals considerable discrepancies in the estimated areas and the associated gas velocities. 304 is the more economical of the two and still offers good corrosion resistance. 1205/cherd06101. Pressure drop at the flood point as a function of ioad-ing. GSP-2: Mellagrid structured packing has smooth surface. In annular strippers, the packing, its support and its hold-down do not touch the reaction riser. The woven wire cloth pieces are corrugated and then assembled into structured packings. The modeled object was the plate-type structured packing Mellapak 250. For improved capacity. The PACK-13 C was fabricated by suppressing double layer silk screen, made of stainless steel, into the corrugated shape, and then numbers of plates were assembled as structured packing: the inclination angle and height of the corrugation were 45° and 2. The polluted air was generated through the vaporization of liquid VOC (contained in a gas-tight syringe) in the air stream by means of a syringe driver, to reach VOC concentrations between 20 and 110 mg C m −3 . Structured Tower Packing. Typically used in vacuum to moderate pressure applications, it offers low pressure drop and good efficiency in hydrocarbon and other applications. 6. Thus, at high gas loads, drainage of liquid from packing elements is difficult. Styrene is a chemical used to make latex, disposable cups, plastic packaging and many other commonly used products. 210 mm diameter May 1, 2003 · Abstract. [Pg. Feb 4, 2024 · Yes, Mellapak 200 structured packing is the same as Nutter B-1 200 Structured Packing, which is a high-performance packing designed for a variety of mass transfer and separation processes. Pressure drops were calculated using the Kister and Gill GPDC interpolation charts (Sec. 1: History of structured packing development. The standard of such a specific surface area (SSA) is 250 m2/m3. With the bias plot, practitioners can gather more information about a correlation underpredicting or Plastic Structured Packing. (8. DOI: 10. g. Y being a typical example of plate packing used probably most often in industry in the recent years. e. Reduce bed depth; Minimize plugging; Maximize gas distribution in the bed; Increase capacity in the unit; Reduce fuel costs; Lower pressure drop; Utilize entire Oct 1, 2011 · This principle has suggested the use of a single, characteristic HETP value for each packing. Experiments were carried out on the 10- and 19-layer packing with an overall height of 2. The experiments were done in a. 1. 2. 196 m. Intermediate sizes can be provided to suit a particular case. 55 m3/m3 [5], this type of packing is used even today. 2. Multiple researchers have shown promising results for using an REU’s CFD performance to predict the performance of the structured packing as a whole ( Basden, 2014 , Erasmus, 2004 , Lautenschleger et Around the world, customers count on Koch-Glitsch to keep their operations running with a wide range of innovative products and solutions serving the refining, chemical, petrochemical and gas processing industries. This work shows that structuring training data to increase semantic interdependence is an effective strategy for optimizing context utilization. A patented,aggressively textured surface, combined with patented corrugation reversals in each packing layer,along with other subtle proprietary geometric features, give INTALOX structured packing a higher capacity. Yet, their real-world applications are often hindered by ineffective context information use. We design it to direct the variety of fluids on the complicated paths inside the columns. In this paper, a 3D structured packing composed of a mesh structure and a support structure was designed. 3. Aug 15, 2010 · A new structured packing using carbon fibres, called Sepcarb ® 4D, is presented. Mar 1, 2010 · The new structured packing of PACK-13 C was a combination of advantages of structured packing and random packing, as shown in Fig. Column packings applicable to the field of rectification are mainly characterized by their number of theoretical stages per meter NTSM (m –1 ), specific pressure drop per height Δ p (mbarm –1 or Pam –1 ), and capacity limits. A demister pad is similar to an air filter, which is used for removing dust particles from a stream of air. It is widely used in absorption and distillation columns and chemical reactors. Structured packing favors well in situations where low pressure drop is required. The precise knowledge of separation efficiency and the ability to compare different types of Feb 1, 2022 · Structured packing chemical systems with a small concentration jump at the interface are often liquid-film controlled, which differs from typical structured packing chemical systems where the majority of the mass transfer resistance is often in the gas phase [5, 12, 88]. 331] Figure 9-64. The Raschig Super-Pak ® is a structured packing designed to allow free flow of Sulzer structured packing portfolio The complete range Metal sheet packings Gauze packings Special packing types Column internals Services 4 8 11 16 18 Structured packing is one of our core abilities. Structured metal packings are available too. Abstract. FLEXERAMIC ® structured packing can process 30% more gas flow than ceramic saddles (random packing) 30% more gas flow results in 30% more acid production. To this end, we introduce Structured Packing for Long Dec 4, 2001 · Comprehensive experimental and modeling studies conducted recently with various types and sizes of Montz structured packing have revealed most performance-related secrets of this gas−liquid contacting device. , 750 m2/m3). The design of structured packing is based on creating a large number of small, uniform flow channels that enhance mass transfer between the liquid and vapor phases. random packing에 비해 가장 큰 장점은 HETP가 작고 (보통 0. The material thickness of such a packing is normally 0. PTFE Structured Packing refers to a range of specially designed materials for use in absorption and distillation columns and chemical reactions. GSP-3: F-grid structured packing has less height than common structured packing. Raschig Super-Pak®. ME-II 750 Y. 1021/ie001032y. 12 m and height Z = 1 m) was filled with a Flexipac® 500Z HC structured packing. Structured packing is a kind of filler which at uniform geometry arranged and neatly piled in the tower. Nov 2, 2021 · An REU captures the repeating geometry of structured packing and is effectively the building block of a structured packing, as shown in Fig. Structure of structured packing. They usually consist of thin corrugated metal plates or gauze, designed to force fluids on complicated paths throughout the column. Building on these findings, but with a broader focus, we introduce Structured Packing for Long Context (SPLiCe). Wire gauze packing is a type of newly popular structured packing. Features and benefits At the lower and upper end of each packing element, the orientation of the corrugation gradually approaches the vertical axis. Jun 9, 2022 · Here, the structured packing without a microstructure again indicates a lower amount of foam inside the column compared to the structured packing with microstructure. Each segment rests on an annular support ring and, when necessary, beams. Their main application fields are in distillation, desorption, absorption, direct heat exchanges and liquid / liquid extraction. GSP-4: Nutter grid structured packing is suitable for coking application. 350. Unfortunately the channel opening angle, an important geometrical parameter of structured packing, has received only little attention until now. construct the structured packing. Laboratory-scale experiments are performed to varying extents, and DURAPACK® structured packing can be used either in glass columns or in columns made of other material such as glass-lined steel, PTFE-lined or Tantalum cladded materials. SPLiCe starts by picking a random document from the dataset to create a single-node tree and continues in a breadth-first manner, each time appending top Ceramic Structured Packing – Excellent Corrosion and Chemical Resistance. The neighbor corrugated sheets are placed oppositely and then assembled into packs with geometric structure. Various structured packing designs are Structured Packing. They showed that Eq. Nov 15, 2023 · The structured packing used in all the experiments presented was an unperforated structured packing from Sulzer Chemtech Ltd with a similar design to the Sulzer Mellapak 500. Other column internals, such as liquid and vapor distributors, are important Dec 10, 2018 · Extensive usage of the structured packings in various industrial applications has led to comprehensive investigations of their properties and performance. A CFD model of the two-phase countercurrent flow in the geometry of the plate-type structured packing Mellapak 250. The demister pads are used to removing micron-size liquid particles from a vapor stream. Lower liquid content, meaning lower “hold up”. , which have irregular shapes and are packed randomly inside columns. The wire gauze packing is made of several pieces of woven wire cloth. 9). X- or Y-design with 45° or 60° corrugation angles. In addition to random tower packings and mass transfer trays, structured packings represent a further group of products that are used in the field of mass and heat transfer processes. However, structured packings, such as corrugated sheets, have an even lower pressure drop than random packing. 1) to their massive data banks for second- and third-generation random packings (60) and for structured packing (60a). Sep 1, 2022 · As the core component of the rotating packing bed, packing is a place for efficient gas–liquid mixing and mass transfer. , 1988. This approach has remained fundamentally the same since the earliest publications on the subject ( Eiden et al. Oct 12, 2022 · Table 3 shows the commercial structured packing used for the comparison with the 3D foam-printed packing in terms of mass transfer efficiency. Structured packings tend to offer lower pressure drop and increased capacity when compared to random packings discussed above. After smooth steering flow by the horizontal radial flow down and then upward, so which liquid can be Jan 1, 2003 · The standard structured packing with a corrugation angle of 45° results in a 90° change in the gas flow direction at the transitions between packing elements (layers) which at higher gas loads causes pronounced liquid build-up. The second part covers the generation of effective interfacial area and provides a general correlation for predicting the mass-transfer efficiency as a function of surface KFBE packing is used in both annular strippers (those with a reaction riser in the middle of the stripper) and full-circle strippers. Numerical simulations were made for the unsteady twophase flow with free liquid surface in the duct between two flat or corrugated plates. A. Jul 19, 2018 · Random packing is one of the 3 primary devices used in mass and heat transfer applications. Widely variable geometrical shape and different surface structures. 77–0. Finally, the results were compared, to investigate the transferability and information value of the new measuring cell in comparison to conventional columns. This work studies different ways of artificially-created nonuniform irrigation of packing. 10. These properties are advantageous for packing used as a gas–liquid contactor for separation units. Structured packings must be designed and constructed to specific columns. Further, pressure drop per theoretical stage is far lower for structured packing than for random packings (Sec. This stack was then inserted into an open-ended cylindrical surface to approximate a packed Specs, Features, & Characteristics. Distillation is the most important thermal separation process, with separation efficiency as one of the fundamental parameters to influence economy and energy consumption. The most important design criteria are: HETP values (m packing height per theoretical stage). Ceramic structured packing has similar structure with grid structured packing, which is composed of several smooth surface corrugated sheets in 60° or 45°. Structured Packing for Long Context (SPLiCe) We propose SPLiCe , a method that creates training examples by building a tree of documents, see Algorithm 1 and Figure 1 for a general overview. PREDICTING PERFORMANCE OF RANDOM AND STRUCTURED PACKING The selection of tower internals for distillation has been well reviewed by Pilling and Holden (2009). ME-II® structured packing, is an efficient and economical product. FLEXERAMIC ® Ceramic Structured Packing. Chemical Engineering Research and Design 2007, 85, 118-129. Jul 20, 2021 · The packed column (internal column diameter D col = 0. 10). N (standard model) or S (high performance model) The structured plastic packings are summarized in the RPP series. Higher separation efficiencies than with trays. Oct 15, 2008 · Structured packings are efficient gas–liquid contacting devices and have been widely used in many industrial applications for decades. 5m 이하) 차압이 작아 (대략 100Pa/m) 분리가 어려워 많은 단수를 요구하는 column이나 vacuum이 높게 요구되는 column, 혹은 capacity를 Aug 1, 2011 · Structured packing efficiency—Vital information for the chemical industry. 50% lower pressure drop as compared to ceramic saddles (random packing) with the same gas flow. Among various methods of modeling, computational fluid dynamics (CFD) is an efficient approach to present full details of fluid behavior inside structured packings. , 1995, Hufton et al. Experimental studies were conducted to test the packing pressure drops and liquid distributions, while a numerical method using CFD method was used to investigate and optimise the packing parameters. Oct 15, 2020 · Structured packing is more costly than random packing and does well in environments that require high capacity and efficiency. Y. In this study, a volume of fluid multiphase-flow model for two adjacent sheets of a Gempak 2A structured packing was used to investigate the effect of gas and liquid velocities Structured packing is often used as an alternative to random packing materials, e. Over 50 years of experience in development, design, and fabrication of this type of packing makes us your best partner to find the optimum solution Apr 21, 2022 · It should be stated that this structured packing is regarded as a class of the Y-type and X-type with the corrugation angle of 45° and 60°, respectively. Structured packing refers to a range of specially designed pack in different geometric structure and different materials. Feb 1, 2024 · Kister and Gill compared flood-point predictions from Eq. Figure 2 shows three groups of curves, namely for corrugation angles of φ = 60°, 45° and 30°. The results for these systems (C6/C7 and O/P-xylene) are broken down further with the bias plot in Fig. Y was built, tested and verified. , 2001). Packing types with an angle of 45° are known as Y-types whereas X-types have commonly a 30° angle. Nov 4, 2011 · structured packing with a regular shallow em bossed unperforated surface, a corrugation. ME-II 500 Y. The heavy naphtha -Ught gas oil fractionation zone of a crude tower has to be revamped to handle 25% more capacity. These types of packing are usually made from Oct 1, 2021 · In this study, a novel 3D printed structured packing, SpiroPak, has been reported and studied to investigate its hydrodynamic performance. It is widely used in many fields for large surface area, low pressure drop, uniform fluids, heat and mass transfer efficiency and other advantages. ME-II 350 Y. The results of these experiments are compared with the data for uniform irrigation of packing, all other things being equal. Previously reported fires with titanium structured packing tended to involve supplementary fuels such as combustible organic deposits and/or pyrophoric materials (e. (The other 2 devices are structured packing and trays. For example, structured vs. Dec 28, 2023 · Recent developments in long-context large language models have attracted considerable attention. As the core component of the rotating packing bed, packing is a place for efficient gas–liquid mixing and mass transfer. Structured packings take up very little cross section space within the column (around 1%) and allow vapor to flow through them in a continuous phase. Olujic. Low pressure drop, which leads to reduce energy consumption largely. SPLiCe is an innovative method for creating training examples by using a retrieval method to collate the most mutually relevant documents into a single training context. 500. Therefore, the surface area is wetted by the liquid at very low liquid loads as are typically encountered in vacuum applications. , Raschig rings, Pall rings, Saddles etc. Industrial & Engineering Chemistry Research 2001, 40 (23) , 5140-5146. Mar 2, 2023 · Structured packing is a crucial component of distillation columns, providing high surface area for mass transfer and low pressure drop. Structured packing is consists of thin metal plate sheets or wire gauze. It has all the desirable characteristics including predictable throughput, low pressure drop, high efficiency and flexibility which plays vital role in separations. Specification. Introduced in 1986,INTALOX structured packing was shown to have greater "efficient capacity" than other struc- tured packings. At the same time, they try to maintain low resistance to flow. It combines all advantages of the metal sheet packing Mellapak with new geometrical features. Compared with other established gas−liquid contacting devices, structured packings are generally known as having the lowest pressure drop per theoretical tray. The recent developments of new generations of high performance packings are included. In packed columns, mass transfer efficiency is related to intimate contact and rate transfer between liquid and vapor phases. The mass transfer area of nine structured packings was measured as a function of liquid load, surface tension, liquid viscosity, and gas rate in a 0. 750. The most used concept to evaluate the height of a packed column, which is related to Dec 29, 1998 · How to Surpass Conventional and High Capacity Structured Packings with Raschig Super-Pak. This principle tends to apply to random packing and to sheet-type structured packing, but not to gauze and mesh type packing. In contrast, reproducible measurements were only possible for the value of the critical fan duty D Fan,crit in the event of excessive foaming of the structured packing and are Mar 1, 2020 · Structured packing is designed with high surface-area-to-volume ratios, and to maximize liquid spreading. 4. To determine the internal May 21, 2020 · Random packing is suitable for any size tower, and the size of the tower will determine how much packing is needed. Sep 1, 2006 · In this study, an innovative wire gauze structured packing, namely PACK-1300XY with a specific surface area of 1300 m2/m3 has been characterized by performing computational fluid dynamics (CFD Structured Packing Support Grids are designed for ease of installation and are segmented to fit through column manways. 316 is a more durable option with a higher nickel content and two percent molybdenum for additional protection against oxidation. ) Like the other 2 devices, the primary purpose of random packing is to create surface area for vapor/liquid contact so that Mother Nature (and Father Thermodynamics) can produce chemical separation. This earlier work, by itself, suggested that clean titanium would not propagate sustained burning in air at atmospheric pressure. Some common materials used in structured packing include metal, plastic, or ceramic (Olujic et al. 8 in) ID column via absorption of CO₂ from air into 0. Surface tension was decreased from 72 to 30 mN/m via the addition of a surfactant (TERGITOL [trademark] NP-7). Jan 8, 2024 · Understanding Structured Packing: Structured packing is a specialized form of packing material used in distillation columns to facilitate the separation of components within a mixture. inclination angle of 45º and an element height of 0. Savings due to the reduced height usually outweigh the additional packing cost. . Less known is the fact Jan 1, 2014 · Structured packing is manufactured in various types, geometries, and materials, which are addressed in this chapter. An electronic representation of Sulzer’s Mellapak N250Y structured packing was generated by subjecting a physical packing element to CT scan. FLEXERAMIC ® structured packing provides 35% lower pressure drop as compared to 1” ceramic saddles at the same gas flow Download Brochure. Cold and hot wall units KFBE packing is used in both cold wall and hot wall catalyst strippers. Despite the low specific surface a = 45–100 m2/m3 and the low free volume ε = 0. Material: SS304, SS304L, SS316, SS316L Oct 29, 2017 · Advantages of the structured packing: Lower pressure losses. 1 mol/L NaOH. 427 m (16. 1 Structured packing is a range of materials that are specially designed for use in distillation and absorption columns, as well as chemical reactors. Dec 6, 2019 · Taking various precautions while installing the column packing and column internal mechanisms will result in optimal tower performance. 1). Structured Packing refers to the variety of materials that are specially designed for the improvement of the efficiency of the distillation, absorption columns, and a few chemical reactors. In QVF® glass columns up to a nominal width of DN1000 the gap between the packing and the inner column wall is closed by the standard wall wipers. The performance characteristics of various packing types (i. 9 m. Benefit is 50% energy savings. Jul 25, 2021 · Structured Packing wire mesh나 perforated metal sheet로 규칙적인 배열로 겹치게 만들어 void fraction이 크고 surface area가 크다. Unlike This chapter deals with column packing effici ency, considering the main studies including random and structured packing columns. High flux and small resistance, make high distillation efficiency. FLEXIGRID® and GLITSCH GRID® severe services grid packings are specifically designed to provide reliable operation in severe services that are susceptible to fouling, erosion, coking, and high solids content. As a full-service provider of mass transfer, mist elimination, and phase separation equipment, we can handle everything from design Apr 9, 2021 · Structured packing is 50% more efficient than tray technology and can be used to decrease the diameter of the absorption column, which significantly reduces costs. Hydrodynamic-analogy-based model for efficiency of structured packing columns. Learn more about the features, benefits, and applications of each packing type from the brochure. These packing were selected based on different type (gauze or corrugated sheets), geometry (nominal area, void fraction and corrugation angle), material construction (metallic and plastic). Fig. Kenig, Z. Combining excellent performance characteristics with Figure 2 shows three groups of curves, namely for corrugation angles of φ = 60°, 45° and 30°. Shilkin, E. Packed columns have a lower pressure drop because the packing has a greater open area compared to trays. In CO 2 removal in LNG plants, packing has tended to be used less frequently, but there are Sep 1, 2022 · Abstract. Larger throughput capacity than with trays. 1. zv bx et hr ap al wz oq jn uf