Maximum Allowable Pressure Research Articles

Maximum Allowable Pressure Calculation of Water Tube Boiler during Operation

In the steam boiler industrial sector, pressure and temperature of the water tube are the two main factors that affect the safety and efficiency of a steam boiler. Explosions may be occurring because of a sudden drop in pressure without a corresponding drop in temperature. Therefore, understanding the temperature distribution of the water tube boiler is essential to control the failure and explosion of the boiler. Once the temperature distribution is known than the limiting factors that affect the water tube life such as the maximum allowable pressure can be determined. ANSYS software will be used to determine the temperature distribution in the water tube of a utility boiler during operation at elevated inlet water and furnace temperature. The theory of axisymmetric has been utilized since the water- tube is cylindrical in shape. In axisymmetric theory, a three-dimensional cylindrical problem like a water tube can be reduced to two-dimensional by ignoring the circumferential Ө, while the r-axis and z-axis became x-axis and y-axis or Cartesian coordinate. Then two-dimensional rectangular elements meshing for the profile cross-section along the water tube in r and z axes were implemented in a computerized simulation using ANSYS 10 to find out the steady-state temperature distribution of the water tube.

Simulation of acetone-water explosion in hydrothermal extraction reactor

This work investigates possible factors that lead to acetone-water explosion in a hydrothermal extraction reactor that happened in our laboratory. To begin with, acetone-water reactivity was checked in CAMEO. Next, pressure build-up curves at varying operating conditions were simulated in Aspen Batch Modeler. Analysis of variance (ANOVA) was conducted in IBM SPSS Statistical Software to determine the most significant factors causing the explosion. Results from CAMEO showed that the explosion was a boiling liquid expanding vapour explosion (BLEVE). Outputs from Aspen simulation indicated that the reactor pressure rise increased with the increment of acetone ratio, heating temperature and reactant total volume. The reactor wall ruptured as the pressure exceeded the maximum allowable working pressure. IBM SPSS showed that the heating temperature was the most significant factor causing the pressure to build-up within the reactor, followed by the acetone-water ratio and total reactant volume. Among all three factors, the heating temperature added to largest pressure build-up, especially when the temperature was increased near to 360 °C. The time required to trigger explosion was predicted to be within 13.8–15 min of heating.

Size optimization of heat exchanger and thermoeconomic assessment for supercritical CO2 recompression Brayton cycle applied in marine

When the state-of-the-art supercritical CO2 cycle is applied to the marines, priority should be given to the feasibility of its component size. In this study, a thermodynamic model of the marine supercritical CO2 recompression cycle was developed. To evaluate the thermoeconomic and component size of the system, the recuperator and precooler with a microtube structure were designed. After quantitatively discussing the impact of the two-stage compression mode on the component scale, the sizes of the heat exchangers were optimized based on the maximum allowable pressure drop. The parameter analysis demonstrates that increasing the speed of the power turbine is beneficial to the system thermoeconomic. Not only can an efficiency improvement of 1.73% and a cost saving of 1.77 $/MWh be achieved, but also the implementation of two-stage compression reduces the volume of the high-temperature recuperator, low-temperature recuperator, and precooler by 4.62%, 6.33%, and 37.4%, respectively. The size optimization analysis suggests that the direction with the longest distance should be regarded as the length constraint of the heat exchanger design in the absence of multi-objective optimization. Moreover, this study has guiding significance for the size optimization of the supercritical CO2 cycle used in a limited space.

Designs for Reliability and Failure Mode Prevention of Electrical Feedthroughs in Integrated Downhole Logging Tools

Abstract To enable an electrical feedthrough integrated down-hole logging tool to maintain high reliability during its logging service in any hostile wellbores, it is critical to apply some guidelines for the electrical feedthrough designs. This paper introduces a safety factor-based design guideline to ensure an integrated electrical feedthrough has sufficient compression or thermomechanical stress amplitude in the stress well against potential logging failures. It is preferred to have a safety actor of 1.5–2.0 for an electrical feedthrough at lowest temperature, such as −60°C, and a safety actor of 2.5–5.0 at operating temperature range of 200–260°C. Moreover, the designed ambient pressure capability should be 1.5–2.0 times higher than the maximum downhole pressure, such as 25,000–30,000 PSI. To validate this thermomechanical stress model, several electrical feedthrough prototypes have been tested under simulated 200–260°C and 31,000–34,000 PSI downhole conditions. The observed testing data have demonstrated that there is a maximum allowable operating pressure for an electrical feedthrough operating at a specific downhole temperature. It is clearly demonstrated that an electrical feed-through may operate up to 60,000 PSI at ambient temperature in a real-life application, but it may actually operate up to 30,000–35,000 PSI at 200–260°C downhole temperatures.

A comprehensive sensitivity analysis on the performance of pseudo‐steady propane thermal cracking process

AbstractThe propane thermal cracking reactor process is investigated in an industrial furnace with an alternative wall burner arrangement. Temperature and heat distribution of the furnace is obtained by three‐dimensional computational fluid dynamics (CFD) simulation technique using Ansys Fluent software. Ten calculation domains are adopted to decrease calculation costs. Different fuel rate ratios are selected as the main effective parameter on reactor performance. Different ratios of base fuel rate (0.0695 kg/s) have been considered. The obtained reactor tube wall temperature profile is used for a one‐dimensional pseudo‐steady reactor operation. By the proposed new arrangement, the created coke layer thickness is lower about 3 mm compared with the base case after 700 h. Meanwhile, Propane conversion is increased by 4%. Besides, reactor feed flow rate variations are considered one of the essential parameter on reactor operation. Despite surging in propylene yield after coke formation, ethylene yield decreases during the process. By increasing the fuel rate in each reactor flow rate, ethylene increased while propylene yield descended. The maximum allowable pressure drop is 2.7 bar. At 0.5ṁ fuel rate and 0.85 kg/s reactor flow rate, pressure drop, reactor lifetime, and ethylene yield are 1.23 bar, 1444 h, and 28%; respectively. In the reactor flow of 0.85 kg/s, by raising fuel rate 0.5–2ṁ ethylene yield is increased from 28% to 46.83%, while process operating time is reduced to 780 h. According to the results, 0.8–0.85 kg/s could be considered as an appropriate range for reactor feed flow rate.

Physical and Mechanical Properties of Hollow Fiber Membranes and Technological Parameters of the Gas Separation Process.

The porous layer of composite and asymmetric hollow fiber membranes acts as a support and is exposed to strong mechanical stresses. The effect of external pressure on the polymer structure and, as a consequence, the separation characteristics of the membrane remains unsolved. Based on the solution of the Lamé approach to the calculation of the stress state of a hollow cylinder, a method of calculation was proposed for hollow fiber membranes. Calculations were based on the approximation of the isotropic nature of the physical and mechanical characteristics of the selective layer and substrate. Permissible deformation of the membrane’s selective layer was determined from the linear sector of strain-on-stress dependence, where Hooke’s law was performed. For these calculations, commercial polyethersulfone membranes were chosen with an inner and/or outer selective layer and with the following values of Young’s modulus of 2650 and 72 MPa for the selective and porous layers, respectively. The results obtained indicate that the dependence of the maximum allowable operating pressure on the substrate thickness asymptotically trends to a certain maximum value for a given membrane. Presented data showed that membranes with outer selective layer can be operated at higher working pressure. Optimal parameters for hollow fiber gas separation membrane systems should be realized, solving the optimization problem and taking into account the influence of operating, physicochemical and physicomechanical parameters on each other.

Mechanical Design of Slug Catcher

In the upstream oil and gas industry Slug Catcher is a separator to separate heavy liquid hydrocarbons and the gaseous lighter fraction. Slug Catcher is a cylindrical pressure vessel which has a horizontal orientation designed with an internal pressure of 84.37 kg/cm2 , 73,89 °C temperature, 3 mm corrosion allowance, 3,500 mm length, and 1,750 mm diameter. This paper aims to design a Slug Catcher from a mechanical side that is safe and able to withstand the stress caused by internal pressure. General design which includes calculation of thickness of shell, heads, and nozzles, maximum allowable working pressure (MAWP), and minimum design metal temperature (MDMT) using ASME BPVC Section VIII Division 1. Based on the results obtained the nominal shell thickness is 60 mm, head minimum thickness 58 mm, material specification for shell and head is SA 516 Gr 70. In general, the selected material use low carbon steel; flange rating class 600; vessel’s Maximum Allowable Working Pressure is 87.60 kg/cm2 ; hydrostatic test pressure is 113 kg/cm2 .

Thermodynamic analysis of a hydrogen fuel cell waste heat recovery system based on a zeotropic organic Rankine cycle

In this study, a thermodynamic model of a hybrid system consisting of a proton-exchange membrane fuel cell (PEMFC) system and an organic Rankine cycle (ORC) system is established using Aspen Plus software. The optimal working fluid is selected by comparing the performance of pure working fluids and zeotropic mixtures of working fluids in an ORC system. The zeotropic working fluid consisting of R245fa/R123 with a mixing ratio of 0.6/0.4 shows the best performance. The effects of some key parameters, including the current density and operating temperature, on the performance of the PEMFC–ORC system with zeotropic mixing fluids are discussed. The results indicate that the power and efficiency of the PEMFC–ORC system with the zeotropic mixing fluid increase with increasing operating temperature. When the R245fa/R123 zeotropic working fluid with a mixing ratio of 0.6/0.4 is used, the net power and efficiency of the hybrid system reach optimum values under the studied boundaries, with improvements of 12.87% and 4.84%, respectively. The influence of the maximum allowable evaporation pressure and stack operating temperature on the selection of optimum working fluid for the hybrid system is discussed in addition.

Designs for reliability and failure mode prevention of electrical feedthroughs in integrated downhole logging tools

Abstract To enable an electrical feedthrough integrated downhole logging tool to maintain high reliability during its logging service in any hostile wellbores, it is critical to apply some guidelines for the electrical feedthrough designs. This paper introduces a safety factor based design guideline to ensure an integrated electrical feedthrough has sufficient compression or thermo-mechanical stress amplitude in the stress well against potential logging failures. It is preferred to have a safety actor of 1.5~2.0 for an electrical feedthrough at lowest temperature, such as −60°C, and a safety actor of 2.5~5.0 at operating temperature range of 200~260°C. Moreover, the designed ambient pressure capability should be 1.5~2.0 times higher than the maximum downhole pressure, such as 25,000~30,000PSI. To validate this thermo-mechanical stress model, several electrical feedthrough prototypes have been tested under simulated 200~260°C and 31,000~34,000PSI downhole conditions. The observed testing data have demonstrated that there is a maximum allowable operating pressure for an electrical feedthrough operating at a specific downhole temperature. It is clearly demonstrated that an electrical feedthrough may operate up to 60,000 PSI at ambient temperature in a real life application, but it may actually operate up to 30,000~35,000 PSI at 200~260°C downhole temperatures.

Evaluasi Desain Bejana Bertekanan pada Radiator Cooling System Menggunakan Material SPCC-SD

This study discusses the analysis of a pressure vessel's design in the Radiator Cooling 1000 (RC-1000) system, which operates at a design temperature of 110 o C. A pressure vessel is a container of gaseous, solid, or liquid material subjected to internal or external pressure and can withstand various other load variations. The pressure vessel on the RC-1000 system has a outer diameter of 87.8 mm or 3.46 inches and will experience an internal pressure of about 20.84 psi or 143.7 kPa , so it must be designed safely. This research method uses analytical and experimental methods. The analytical method is used to calculate the thickness of the pressure vessel material, the maximum allowable working pressure, and the hydrostatic test calculation. While the experimental method was carried out on the hydrostatic test process, the evaluation was based on the prevailing regulations in the Republic of Indonesia. Using the SPCC-SD material (JIS 3141), it was found that the minimum thickness of this pressure vessel is 0.0453 inches on the shell side and 0.0435 inches on the head/head side. The thickness of the material used on the shell side and head/head is 0.0472 inches in practice. This pressure vessel has passed the hydrostatic test at 232.1 psi or 1600 kPa.

Finite Element Analysis of Composite Repair for Damaged Steel Pipeline

Carbon fiber reinforced polymer (CFRP) matrix composite overwrap repair systems have been introduced and accepted as an alternative repair system for steel pipeline. This paper aimed to evaluate the mechanical behavior of damaged steel pipeline with CFRP repair using finite element (FE) analysis. Two different repair strategies, namely wrap repair and patch repair, were considered. The mechanical responses of pipeline with the composite repair system under the maximum allowable operating pressure (MAOP) was analyzed using the validated FE models. The design parameters of the CFRP repair system were analyzed, including patch/wrap size and thickness, defect size, interface bonding, and the material properties of the infill material. The results show that both the stress in the pipe wall and CFRP could be reduced by using a thicker CFRP. With the increase in patch size in the hoop direction, the maximum von Mises stress in the pipe wall generally decreased as the maximum hoop stress in the CFRP increased. The reinforcement of the CFRP repair system could be enhanced by using infill material with a higher elastic modulus. The CFRP patch tended to cause higher interface shear stress than CFRP wrap, but the shear stress could be reduced by using a thicker CFRP. Compared with the fully bonded condition, the frictional interface causes a decrease in hoop stress in the CFRP but an increase in von Mises stress in the steel. The study results indicate the feasibility of composite repair for damaged steel pipeline.

Effect of Depletion and Fluid Injection in the Mesozoic and Paleozoic Sandstone Reservoirs of the October Oil Field, Central Gulf of Suez Basin: Implications on Drilling, Production and Reservoir Stability

This work attempted to understand the behavior of the Upper Cretaceous Nezzazat and Lower Cretaceous–Carboniferous Nubia sandstone reservoirs in response to production-induced depletion and fluid injection for enhanced hydrocarbon recoveries from the October oil field, Gulf of Suez, Egypt. Pore pressure (PP), vertical stress (Sv) and minimum horizontal stress (Shmin) magnitudes were modeled based on well logs, drilling data and subsurface measurements. The latest measurements indicated 11.7–12.7 MPa pressure drop (ΔPP) in the Nezzazat reservoirs, while the Nubia sandstone reservoir was depleted by 19–21 MPa. Revised PP and Shmin gradients offer a narrow mud weight window of 9–10.7 PPG (pore pressure gradient) if the entire Lower Miocene–Carboniferous section was planned to be drilled with a single casing in the infill/injector wells. A more conservative approach will be to drill the depleted reservoirs with 5.5–9.3 PPG mud window and case separately, although that may incur an additional cost. Based on the PP–Shmin poro-elastic coupling, stable stress path values of 0.61 and 0.65 are interpreted in the Upper and Lower reservoirs, indicating depletion-induced normal faulting is unlikely to occur at the present rate of depletion. The reservoir stability threshold during pressurization was assessed for fluid injection optimization to sustain production and curtail the bypassed oil. The maximum allowable pressure build-up during injection was estimated using various possible pore pressure–stress coupling scenarios at their maximum depletion state. Based on the PP–Shmin coupling approach, maximum pressure increments of 23 and 27 MPa can be permitted in the depleted Nezzazat and Nubia sandstone reservoirs during injection, without exceeding the lower limit of caprock Shmin, as applicable for both the reservoirs. This will ensure the geomechanical stability of the reservoirs as well as the caprock integrity. This geomechanical study provides crucial comprehensions regarding the optimization of drilling, production, and fluid injection by reducing the risk of reservoir instabilities and formation integrity.

Analysis of Crack Initiation and Propagation Thresholds of Inclined Cracks under High-Pressure Grouting in Ordovician Limestone

Control of the grouting pressure within the critical grouting pressure for crack propagation in Ordovician limestone can not only ensure grout penetration length, but also prevent the risk of creating an artificial water channel. Based on the fracture mechanics theory, a formula was proposed to calculate the critical grouting pressure of mixed mode I-II cracks in Ordovician limestone. The necessary conditions for tilted crack opening, the rationality of the existing empirical value of the maximum allowable grouting pressure was investigated based on the mechanical model. The RFPA2D-Flow numerical simulation software was used to evaluate the deduced theory. The research results show that the deduced theoretical calculation formula of the critical grouting pressure agrees with the numerical simulation results; when the mixed mode I-II fracture initiation occurs, the grouting pressure exceeds the perpendicular stress of the overlying rock; the greater the density of the overlying rock mass, the greater the value of grouting pressure for fracture initiation; when the side pressure coefficient was ≥1, crack dip angle increased and the grouting pressure for fracture initiation tended to decrease; and the empirical grouting pressure at the maximum allowable grouting pressure is 2.0–2.5 pw, which will not cause propagation and failure of the existing crack.

Design by analysis of deep-sea type III pressure vessel

This paper explores the potential of hydrogen as an energy carrier for deep-sea applications. Finite element analysis of a type III pressurised cylinder to the intended working pressures of 300 bar internal and up to 600 bar external were carried out for different designs and safety factors. Design parameters such as helical angle, liner, helical, and hoop thicknesses were studied and optimised. A buckling analysis was carried out for the optimised designs and recommendations to increase the maximum allowable external pressure are given.

ЧИСЛЕННЫЙ РАСЧЕТ СТЕПЕНИ ВАКУУМИРОВАНИЯ, ДОПУСТИМОЙ ДЛЯ ГОФРИРОВАННОЙ СТЕНКИ

The article presents a numerical calculation of the corrugated wall of a transformer under pressure. The permissible degree of evacuation of the wavy transformer tank is determined. The statement of the problem is formulated as follows: to determine the limit of the maximum allowable pressure during the evacuation of the tank with different geometrical dimensions of the corrugation. In this case, the maximum equivalent stress should not exceed the yield point and the walls of the corrugation should not close. Numerical calculation is carried out by the finite element method. This approach to calculating the behavior of a corrugated wall under pressure can be used to determine the maximum allowable internal pressure of the tank.

Mechanical properties of a wide range of pipe steels under influence of pure hydrogen or hydrogen blended with natural gas

Hydrogen economy considers hydrogen as a substantial fraction of a nation's energy and services. This could happen in the future if hydrogen can be produced from domestic energy sources economically and in an environmental-friendly manner.Hydrogen can also be used as fuel in stationary fuel cell systems for buildings, emergency power or distributed generation. Hydrogen transport is generally made by pipelines. This solution is preferable than transport on road by truck for security reasons.The addition of hydrogen in natural gas could have an impact on the materials degradation over time especially those used for the storage, transport and distribution of natural gas. The compatibility of these materials with natural gas including of hydrogen is dependent on the proportion of hydrogen added into the gas and is assessed with regard to several criteria:- permeation of hydrogen through metallic materials;- loss of integrity of these materials and adaptation of follow-up actions in service, surveillance and maintenance of equipment.This paper is devoted to the effect of hydrogen embrittlement (HE) caused by adding hydrogen into natural gas network on its design, maintenance, supervision and maximum allowable service pressure (MAOP) for smooth and damaged pipes.

Numerical simulation of filling and evacuating process of impurity gas in target capsule of inertial confinement fusion

Cryogenic target is one of the key components of inertial confinement fusion. The removal degree and efficiency of impurity gas in cryogenic target are of great significance to the on-line preparation of ice layer for cryogenic target fuel. According to the design requirements of cryogenic target physics for impurity content in ice layer, the influence factors of upper limit of partial pressure are analyzed, based on the derivation of the calculation formula of maximum allowable partial pressure of impurity gas in the target. Then the flow field of air and hydrogen in microchannels is investigated, and the filling and evacuation model of gas flow in a microscaled filling tube is established. The dynamic simulations of microtubules with different lengths and diameters are carried out. The results show that the microtubules with a length of 5 mm could save 80% of the time compared with the microtubules of 50 mm in length when the microtubule is 5 μm in diameter. At the same time, the total flow washing time decreases by 46% when the diameter of 2 μm is doubled under the condition of 20-mm-long microtubule. Considering the requirements for efficiency and fusion stability, four kinds of tubes are proposed and simulated. The results indicate that the conical transition tube has a strong flow capacity and high flow evacuation efficiency, and is suitable for use as a filling microtubule. On the basis of the best tube shape, the comparison between the two processes under different intermediate pressures is carried out with the time and number of filling and evacuating serving as evaluation criterion. Ultimately, the intermediate pressure of 52000 Pa is selected, the total number of evacuation is 10 and the time is 758 s. Finally, the effect of temperature on the evacuation efficiency is studied in a temperature range of 113 K－293 K in steps of 60 K. The results show that the total time of filling and evacuation will be reduced by 15% on the basis of normal temperature when the temperature is reduced by 60 K, which proves the feasibility of evacuation at low temperature in practical operation.

ПРОГНОЗИРОВАНИЕ ФУНКЦИОНАЛЬНЫХ ПАРАМЕТРОВ ТЕНЗОЧУВСТВИТЕЛЬНОГО НАНОСТРУКТУРИРОВАННОГО ПОЛИМЕР-КЕРАМИЧЕСКОГО ПОКРЫТИЯ НА ОСНОВЕ АНОДНЫХ ОКСИДОВ МЕТАЛЛОВ

Strength and strain sensitivity of a thin polymer-ceramic coating in the form of a nanoporous anodic aluminum oxide impregnated with a piezoelectric polymer are studied. The coating is considered as a unidirectionally reinforced composite containing cylindrical polymer fibers oriented perpendicular to the coating surface. A three-phase micromechanical model of the specified material is proposed and the stress-strain state of the coating under the influence of uniformly distributed pressure is analyzed. As a result of solving the related problem of electroelasticity, calculated estimates of the specific piezoelectric sensitivity of the coating used as a pressure sensor and the maximum allowable pressure were obtained according to the strength criteria of the ceramic matrix and the plastic flow of the polymer filler. The article shows dependences of the indicated parameters on the volumetric content of the polymer for the coating, adhesively bonded to a non-deformable foundation and freely (without friction) lying on the foundation. At low volume content of polymer, the strength loss of coating is caused by local failure of matrix. At high filler content the transition of polymer into plastic state precedes to the beginning of matrix failure. After increasing the filler content above 80 % the value of maximal pressure according to yield criteria for polymer filler scarcely changes.

Three-dimensional effects influencing failure in bend-free, variable stiffness composite pressure vessels

Pressure vessels enable liquids and gases to be stored and transported safely, finding pervasive use in many industries. These types of structure can be manufactured into many different shapes and from various materials to satisfy the requirements of their specific applications. Maximum allowable pressure is an important factor that should be considered carefully in the design process. Bend-free pressure vessels, that are enabled by variable stiffness composite designs, can even out in-plane stress distributions in the through-thickness direction thereby increasing overall load carrying capacity often accompanied by significant weight reduction. Bend-free composite vessels can therefore be considered to be possible candidates for the next generation of pressure vessels and therefore it is important to study their failure performance, often driven by safety reasons. In this study, the maximum allowable internal pressure is determined for bend-free ellipsoidal pressure vessels exploiting variable stiffness properties, using first-ply failure based on both Tsai-Wu and the recently proposed three-dimensional invariant-based failure criteria with performance subsequently compared against conventional constant stiffness, composite vessels. Parametric studies are then performed to provide physical insight and also to evaluate the effect of various material properties on the difference in failure load prediction found by these criteria.

Maximum Allowable Service Pressure for Steel Pipes Used for Transport of Hydrogen Pure or Blended with Natural Gas

The addition of hydrogen in natural gas could have an impact on the degradation over time of the materials currently used for the storage, transport, distribution and use of natural gas. The compatibility of these materials with natural gas including of hydrogen is dependent on the proportion of hydrogen added to the gas and is assessed with regard to several criteria: Permeation of hydrogen through metallic materials; loss of integrity of these materials and adaptation of follow-up actions in service, surveillance and maintenance of equipment. This paper is devoted to the effect of hydrogen embrittlement (HE) by adding hydrogen into natural gas network on design, maintenance, supervision and maximum allowable operating pressure (MAOP) for smooth and damaged pipes.