Skirt Support Research Articles

Analysis of vertical pressure vessel with skirt support

Analysis of vertical pressure vessel with skirt support

Seismic response of slender storage tanks on tube feet or skirt support

Seismic response of slender storage tanks on tube feet or skirt support

DESAIN REAKTOR TRANSESTERIFIKASI PADA PRAPERANCANGAN PABRIK METIL ESTER DARI CPO (CRUDE PALM OIL)

Along with the development of the era, the need for fuel oil is increasing. The development of research and the use of diesel motors in industry will not stop just because of the depletion of fossil fuels. The search for alternative fuels as a substitute for diesel continues to be carried out in addition to dealing with the problems of the global energy and environmental crisis as well as helping to develop automotive technology as a work of human culture. Methyl ester is a biofuel that can be used to power diesel engines. The availability of fuel oil derived from petroleum is running low and the price is increasing so that alternative fuel sources are needed. One of the substitutes for conventional fuels from petroleum is vegetable oil. Methyl ester is produced using a transesterification reaction by changing the triglycerides which are reacted with one of the alcohol compounds, namely methanol to become methyl ester, and a production capacity of 250,000 tons / year is obtained. The main design tool is the CSTR (Continuous Flow Stirred-Tank Reactor) reactor which is used as a place for the transesterification reaction between triglycerides and methanol to produce methyl ester (main product) and glycerol (by-product). The operating temperature used is 333.15K. Based on the calculation results, the reactor volume is 57.28 m3, the reactor diameter (OD) is 168 in m with torispherical flanged and dished head and skirt support.

Pressure Vessel Design by Design by Analysis Route

Pressure vessels are conventionally designed based on the Design by Rule (DBR) approach. Standard vessel geometries are designed using simple formulae and charts, formulated as standards and codes based on the rules proposed in the ASME Boiler and Pressure Vessel Code and the European Standard prEN13445-3. The stress categorization problem faced employing DBR methodology was overcome by employing Limit Load Analysis using the DBA approach. A simple unfired vertical cylindrical pressure vessel with torispherical pressure head and Y-forged skirt support was analyzed for its structural integrity using ANSYS software. The results obtained for two different materials, high strength steel P500-QT and the conventional low strength steel P355 employing DBA approach was compared with the calculated results using the DBR approach. The maximum allowable pressure (PMAX) for P500-QT material was found to be 2.5X the maximum pressure calculated using the DBR approach as per ASME codes and 3X times as per EN13445-3 standard. For P355 material the maximum allowable pressure (PMAX) was found to be 2.32X the maximum pressure calculated using the DBR approach as per ASME codes and 2.6X times as per EN13445-3. The DBR methodology proves to be highly conservative whereas the use of DBA leads to less conservative design parameters.

Optimal Design of Ammonia Synthesis Reactor for a Process Industry

Ammonia synthesis is a crucial section of ammonia and urea plant. Many industries are facing a challenge of efficient ammonia production every day. In this study, steady state one dimensional pseudo-homogeneous models of an axial flow industrial catalytic packed bed ammonia converter have been developed. The converter is a vertical two catalytic bed reactor with varying volumes of catalysts. Required industrial data for the design were collected from a fertilizer industry in Bangladesh - and the Halder Topsoe process was followed. Differential equations of the - mathematical model were solved using Runge-Kutta-Fehlberg (RKF45) method by Polymath solver software. For a 23.8% single-pass conversion and for a 3 m inside diameter vessel, a total of 22.5 (15 + 7.5) m catalyst bed was required. Pressure vessel wall and head thickness were found 112 mm and 62 mm respectively. Skirt support was selected and the thickness was calculated 12 mm. Pressure drop along the length of the bed was found 2.55 atm. Finally, parameters of the optimized model were compared with the real industrial data and found quite satisfactory.

Optimal slot dimension for skirt support structure of coke drums

The skirt-to-shell junction weld on coke drums is susceptible to fatigue failure due to severe thermal cyclic stresses. One method to decrease junction stress is to add slots near the top of the skirt, thereby reducing the local stiffness close to the weld. The most common skirt slot design is thin relative to its circumferential spacing. A new slot design, which is significantly wider, is proposed. In this study, thermal-mechanical elastoplastic 3-D finite element models of coke drums are created to analyze the effect of different skirt designs on the stress/strain field near the shell-to-skirt junction weld, as well as any other critical stress locations in the overall skirt design. The results confirm that the inclusion of the conventional slot design effectively reduces stress in the junction weld. However, it has also been found that the critical stress location migrates from the shell-to-skirt junction weld to the slot ends. A method is used to estimate the fatigue life near the critical areas of each skirt slot design. It is found that wider skirt slots provide a significant improvement on fatigue life in the weld and slot area.

Finite Element Analysis of Skirt to Shell Junction in a Pressure Vessel

Objectives: The objective of this research work is to find the effect of providing hotbox at skirt to shell junction of a pressure vessel on the stresses induced at this junction. Methods/Statistical Analysis: In present work, since the vessel is to be supported at some elevation from ground, a conical skirt support is used. Two models of skirt to shell junction are made, in Unigraphics 10, one without hotbox while other with hotbox. A thermo-structural analysis of models is performed using ANSYS Workbench15. Stress linearization is done and stresses are limited to code allowable to ensure protection against plastic collapse and local failure. Findings: The result of finite element analysis for the case of model without hotbox shows that thermal stresses as high as 329 MPa are induced at the y-ring, which is much higher than the allowable stress at that temperature. When a hotbox is provided at this region, the stress is found to be reduced to 35.082 MPa, which is less than the allowable stress. So, the vessel will work safely if a hotbox of minimum 480 mm length is provided at the critical junction of skirt and shell. Stress is linearized at five stress classification lines. The linearized stresses and their combinations for four load cases are compared with the code allowable limit, and are found to be less than allowable stress. This ensures the protection of vessel against plastic collapse and local failure. Application/Improvements: Such analysis is needed to be performed for long vessels supported on skirt type of support, as the total vessel loads will be transferred to skirt from this junction only.

Alternate Design of ITER Cryostat Skirt Support System

The skirt support of ITER cryostat is a support system which takes all the load of cryostat cylinder and dome during normal and operational condition. The present design of skirt support has full penetration weld joints at the bottom (shell to horizontal plate joint). To fulfil the requirements of tolerances and control the welding distortions, we have proposed to change the full penetration weld into fillet weld. A detail calculation is done to check the feasibility and structural impact due to proposed design. The calculations provide the size requirements of fillet weld. To verify the structural integrity during most severe load case, finite element analysis (FEA) has been done in line with ASME section VIII division 2 [1]. By FEA ‘Plastic Collapse’ and ‘Local Failure’ modes has been assessed. 5° sector of skirt clamp has been modelled in CATIA V5 R21 and used in FEA. Fillet weld at shell to horizontal plate joint has been modelled and symmetry boundary condition at ± 2.5° applied. ‘Elastic Plastic Analysis’ has been performed for the most severe loading case i.e. Category IV loading. The alternate design of Cryostat Skirt support system has been found safe by analysis against Plastic collapse and Local Failure Modes with load proportionality factor 2.3. Alternate design of Cryostat skirt support system has been done and validated by FEA. As per alternate design, the proposal of fillet weld has been implemented in manufacturing.

Design Study on Skirt Support of Lead-Bismuth-Cooled Fast Reactor Vessel under Seismic Loading

This paper is aimed at analyzing the structural response of reactor vessel for Lead-Bismuth-Cooled fast reactor with cylindrical and conical shell skirt support respectively with a consideration of a fluid-structure interaction in the event of the earthquake. For a seismic design, three kinds of semi-conical apex angles for conical shell skirt support of vessel are analyzed and it is found the conical shell skirt support exhibits the better performance especially when semi-conical apex angle α=15°in the views of the stress intensity and stability.

Optimizing for Lead-Bismuth Fast Reactor Guard Vessel Thickness

In this paper, the thickness of lead-bismuth fast reactor's guard vessel is optimized. The thickness of vessel shell and the thickness of skirt support are chosen as two variables, the effect of thickness on the stress, deformation and thermal stress is considered and the optimal thickness is found.

Stress Analysis of Conical Shell Skirt Support for High Pressure Vessel Using Finite Element Method

Pressure vessel is a closed cylindrical vessel for storing gaseous, liquids or solid products. The stored medium is at a particular pressure and temperature. The cylindrical vessel is closed at both ends by means of dished head, which may be hemispherical, ellipsoidal. The pressure vessels may be horizontal or vertical. The supporting system of this vertical vessel plays an important role in the performance of the equipment. Proper supporting system gives better efficiency. The bottom supports are critical components since they are to be designed with much care to avoid failure due to internal pressure with temperature. In this analysis, skirt support for vertical vessel was analyzed as per the guidelines given in the ASME (American Society of Mechanical Engineering) section VIII division 2 and IBR (Indian Boiler Regulations) standards. The stress analysis was carried out for this support using a general purpose FEM code, ANSYS macros. The coupled field (Structural and Thermal) Analysis was carried out for skirt support to find out the stresses in the support. The analysis’s results were compared with ASME code allowable stress values.

Design by analysis versus design by formula of high strength steel pressure vessels: a comparative study

A comparative study for design by analysis and design by formula of a cylinder to nozzle intersection has been made using different finite element techniques. The cylinder to nozzle intersection investigated is part of a typical vertical pressure vessel with a skirt support. For the study the commonly used ductile P355 steel alloy and the high strength steel alloy P500 QT were considered. The comparative results clearly show disadvantages in terms of limit load capability when the design-by-formula procedures are used in the design of high strength steel pressure vessels. The FE results also clearly show advantages of the shell to solid sub-modeling technique, as it combines the accuracy of 3D-solid modeling with the affordable computing time of the 3D-shell modeling technique.

Cryogenic skirt support post

The cold masses of cryostats having vertical axes, like vertical pressure vessels, can be effectively supported by means of a cylindrical skirt that wraps concentrically around the cold mass. The skirt is a cryogenic support post connected at its upper end to the cold mass and at its lower end to the cryostat vacuum vessel. A heat intercept connection to an intermediate temperature refrigeration source can be employed to control heat leak. The support post consists of a composite; e.g. epoxy fibreglass, or cylinder with bolted or thermal interference fit end connections. The support post, being a single element support, simplifies cryostat assembly and alignment. The composite cylinder, with a relatively large diameter, lends itself to structural soundness and stability under both static and dynamic loading conditions. Its relatively long length and intermediate temperature heat intercept allows low heat leak to the cold mass. The details of the design of a cryogenic skirt support post as applied to a superconducting magnetic energy storage cryostat are presented. Included are support post fabrication, cryostat assembly, and predicted structural and thermal performance. Fabrication of and operational experiences with a prototype support post assembly are discussed.

Temperature Gradients in Skirt Supports of Hot Vessels

A discussion of the variables involved in the temperature gradient along a skirt support for a hot vessel is presented. A method is presented for reasonably approximating the maximum gradient since the temperature curve is rarely linear. For guidance in applying the formula and to illustrate the effect of some of the variables, several basic cases are calculated, using three different skirt support thicknesses and considering bare, fireproofed, and insulated types of skirts. Having a formula for a steady-state temperature along the length of a skirt, it is possible by means of mathematical manipulations to obtain the value of the radius of curvature of the neutral axis at any point. Using this, it is then possible to calculate the axial tension and compression stresses on the inside and outside of a free skirt wall.