当前海洋深水开发所用的浮式平台系统多为浮式船体与柔性系泊系统及立管系统的耦合体,这样,浮式船体与柔性系统之间必将有相互影响及相互作用。由于其整体系统的非线性及动力学特性,势必要求对深水浮式平台系统进行有效的时域耦合分析...当前海洋深水开发所用的浮式平台系统多为浮式船体与柔性系泊系统及立管系统的耦合体,这样,浮式船体与柔性系统之间必将有相互影响及相互作用。由于其整体系统的非线性及动力学特性,势必要求对深水浮式平台系统进行有效的时域耦合分析计算。本文首先简要介绍时域耦合分析的具体问题及解决方法,然后介绍作者近年来开发的HARP(Hu ll A nd R iser P rogram)耦合计算程序。展开更多
This paper presents the analysis of potential thermal cracking of light feedstocks in the SMR. Two different feedstocks, natural gas and light hydrocarbon (HC) feedstock at two different mixed feed inlet temperatures,...This paper presents the analysis of potential thermal cracking of light feedstocks in the SMR. Two different feedstocks, natural gas and light hydrocarbon (HC) feedstock at two different mixed feed inlet temperatures, are selected to study the HC thermal cracking. Effect of Crossover Piping Volume on feed thermal cracking is also discussed.展开更多
In a typical tension leg platform (TLP) design,the top tension factor (TTF),measuring the top tension of a top tensioned riser (TTR) relative to its submerged weight in water,is one of the most important design parame...In a typical tension leg platform (TLP) design,the top tension factor (TTF),measuring the top tension of a top tensioned riser (TTR) relative to its submerged weight in water,is one of the most important design parameters that has to be specified properly. While a very small TTF may lead to excessive vortex induced vibration (VIV),clashing issues and possible compression close to seafloor,an unnecessarily high TTF may translate into excessive riser cost and vessel payload,and even has impacts on the TLP sizing and design in general. In the process of a production TTR design,it is found that its outer casing can be subjected to compression in a worst-case scenario with some extreme metocean and hardware conditions. The present paper shows how finite element analysis (FEA) models using beam elements and two different software packages (Flexcom and ABAQUS) are constructed to simulate the TTR properly,and especially the pipe-in-pipe effects. An ABAQUS model with hybrid elements (beam elements globally + shell elements locally) can be used to investigate how the outer casing behaves under compression. It is shown for the specified TTR design,even with its outer casing being under some local compression in the worst-case scenario,dynamic buckling would not occur;therefore the TTR design is adequate.展开更多
The present theoretical study represents a proposal aimed at investigating about the possibility of generalizing the canonical entropy-exergy relationship and the reservoir concept. The method adopted assumes the equa...The present theoretical study represents a proposal aimed at investigating about the possibility of generalizing the canonical entropy-exergy relationship and the reservoir concept. The method adopted assumes the equality of pressure and chemical potential as necessary conditions of mutual stable equilibrium between a system and a reservoir in addition to the equality of temperature that constitutes the basis for defining entropy as deriving from energy and exergy concepts. An attempt is made to define mechanical and chemical entropy as an additional and additive component of generalized entropy formulated from generalized exergy property. The implications in exergy method and the possible engineering applications of this approach are outlined as future developments among the domains involved.展开更多
The literature reports that equality of temperature, equality of potential and equality of pressure between a system and a reservoir are necessary conditions for the stable equilibrium of the system-reservoir composit...The literature reports that equality of temperature, equality of potential and equality of pressure between a system and a reservoir are necessary conditions for the stable equilibrium of the system-reservoir composite or, in the opposite and equivalent logical inference, that stable equilibrium is a sufficient condition for equality. The aim and the first novelty of the present study is to prove that equality of temperature, potential and pressure is also a sufficient condition for stable equilibrium, in addition to necessity, implying that stable equilibrium is a condition also necessary, in addition to sufficiency, for equality. The second novelty is that the proof of the sufficiency of equality (or the necessity of stable equilibrium) is attained by means of the generalization of the entropy property, derived from the generalization of exergy property, which is used to demonstrate that stable equilibrium is a logical consequence of equality of generalized potential. This proof is underpinned by the Second Law statement and the Maximum-Entropy Principle based on generalized entropy which depends on temperature, potential and pressure of the reservoir. The conclusion, based on these two novel concepts, consists of the theorem of necessity and sufficiency of stable equilibrium for equality of generalized potentials within a composite constituted by a system and a reservoir.展开更多
This paper presents the fundamentals of thermal pyrolysis and discusses the modern ethylene furnace technology and its design trends. Technip’s proprietary SPYRO? program is discussed for prediction of hydrocarbon cr...This paper presents the fundamentals of thermal pyrolysis and discusses the modern ethylene furnace technology and its design trends. Technip’s proprietary SPYRO? program is discussed for prediction of hydrocarbon cracking.展开更多
Among all statements of Second Law, the existence and uniqueness of stable equilibrium, for each given value of energy content and composition of constituents of any system, have been adopted to define thermodynamic e...Among all statements of Second Law, the existence and uniqueness of stable equilibrium, for each given value of energy content and composition of constituents of any system, have been adopted to define thermodynamic entropy by means of the impossibility of Perpetual Motion Machine of the Second Kind (PMM2) which is a consequence of the Second Law. Equality of temperature, chemical potential and pressure in many-particle systems are proved to be necessary conditions for the stable equilibrium. The proofs assume the stable equilibrium and derive, by means of the Highest-Entropy Principle, equality of temperature, chemical potential and pressure as a consequence. A first novelty of the present research is to demonstrate that equality is also a sufficient condition, in addition to necessity, for stable equilibrium implying that stable equilibrium is a condition also necessary, in addition to sufficiency, for equality of temperature potential and pressure addressed to as generalized potential. The second novelty is that the proof of sufficiency of equality, or necessity of stable equilibrium, is achieved by means of a generalization of entropy property, derived from a generalized definition of exergy, both being state and additive properties accounting for heat, mass and work interactions of the system underpinning the definition of Highest-Generalized-Entropy Principle adopted in the proof.展开更多
文摘当前海洋深水开发所用的浮式平台系统多为浮式船体与柔性系泊系统及立管系统的耦合体,这样,浮式船体与柔性系统之间必将有相互影响及相互作用。由于其整体系统的非线性及动力学特性,势必要求对深水浮式平台系统进行有效的时域耦合分析计算。本文首先简要介绍时域耦合分析的具体问题及解决方法,然后介绍作者近年来开发的HARP(Hu ll A nd R iser P rogram)耦合计算程序。
文摘This paper presents the analysis of potential thermal cracking of light feedstocks in the SMR. Two different feedstocks, natural gas and light hydrocarbon (HC) feedstock at two different mixed feed inlet temperatures, are selected to study the HC thermal cracking. Effect of Crossover Piping Volume on feed thermal cracking is also discussed.
文摘In a typical tension leg platform (TLP) design,the top tension factor (TTF),measuring the top tension of a top tensioned riser (TTR) relative to its submerged weight in water,is one of the most important design parameters that has to be specified properly. While a very small TTF may lead to excessive vortex induced vibration (VIV),clashing issues and possible compression close to seafloor,an unnecessarily high TTF may translate into excessive riser cost and vessel payload,and even has impacts on the TLP sizing and design in general. In the process of a production TTR design,it is found that its outer casing can be subjected to compression in a worst-case scenario with some extreme metocean and hardware conditions. The present paper shows how finite element analysis (FEA) models using beam elements and two different software packages (Flexcom and ABAQUS) are constructed to simulate the TTR properly,and especially the pipe-in-pipe effects. An ABAQUS model with hybrid elements (beam elements globally + shell elements locally) can be used to investigate how the outer casing behaves under compression. It is shown for the specified TTR design,even with its outer casing being under some local compression in the worst-case scenario,dynamic buckling would not occur;therefore the TTR design is adequate.
文摘The present theoretical study represents a proposal aimed at investigating about the possibility of generalizing the canonical entropy-exergy relationship and the reservoir concept. The method adopted assumes the equality of pressure and chemical potential as necessary conditions of mutual stable equilibrium between a system and a reservoir in addition to the equality of temperature that constitutes the basis for defining entropy as deriving from energy and exergy concepts. An attempt is made to define mechanical and chemical entropy as an additional and additive component of generalized entropy formulated from generalized exergy property. The implications in exergy method and the possible engineering applications of this approach are outlined as future developments among the domains involved.
文摘The literature reports that equality of temperature, equality of potential and equality of pressure between a system and a reservoir are necessary conditions for the stable equilibrium of the system-reservoir composite or, in the opposite and equivalent logical inference, that stable equilibrium is a sufficient condition for equality. The aim and the first novelty of the present study is to prove that equality of temperature, potential and pressure is also a sufficient condition for stable equilibrium, in addition to necessity, implying that stable equilibrium is a condition also necessary, in addition to sufficiency, for equality. The second novelty is that the proof of the sufficiency of equality (or the necessity of stable equilibrium) is attained by means of the generalization of the entropy property, derived from the generalization of exergy property, which is used to demonstrate that stable equilibrium is a logical consequence of equality of generalized potential. This proof is underpinned by the Second Law statement and the Maximum-Entropy Principle based on generalized entropy which depends on temperature, potential and pressure of the reservoir. The conclusion, based on these two novel concepts, consists of the theorem of necessity and sufficiency of stable equilibrium for equality of generalized potentials within a composite constituted by a system and a reservoir.
文摘This paper presents the fundamentals of thermal pyrolysis and discusses the modern ethylene furnace technology and its design trends. Technip’s proprietary SPYRO? program is discussed for prediction of hydrocarbon cracking.
文摘Among all statements of Second Law, the existence and uniqueness of stable equilibrium, for each given value of energy content and composition of constituents of any system, have been adopted to define thermodynamic entropy by means of the impossibility of Perpetual Motion Machine of the Second Kind (PMM2) which is a consequence of the Second Law. Equality of temperature, chemical potential and pressure in many-particle systems are proved to be necessary conditions for the stable equilibrium. The proofs assume the stable equilibrium and derive, by means of the Highest-Entropy Principle, equality of temperature, chemical potential and pressure as a consequence. A first novelty of the present research is to demonstrate that equality is also a sufficient condition, in addition to necessity, for stable equilibrium implying that stable equilibrium is a condition also necessary, in addition to sufficiency, for equality of temperature potential and pressure addressed to as generalized potential. The second novelty is that the proof of sufficiency of equality, or necessity of stable equilibrium, is achieved by means of a generalization of entropy property, derived from a generalized definition of exergy, both being state and additive properties accounting for heat, mass and work interactions of the system underpinning the definition of Highest-Generalized-Entropy Principle adopted in the proof.
