Pipeline balancing

Pipeline balancing the ASU compositions in terms of abstract building blocks are retimed, and selection of implementations of the building blocks is performed to check whether the proposed clock period can be achieved. If desired, a balancing of the pipelines can be performed to reduce the hardware cost [18]. 

EXU composition/alloc. Pipeline balancing -SFG partitioning ABB/EXU binding Control flow part. -ASU matching... 

The commodity nature of the product and the easy access to the Hcensed processes enable new producers, particularly in developing countries, to enter the global styrene merchant market with Htde experience in styrene technology. Access to ethylene, which caimot be easily transported by means other than pipelines, is a key factor in considering new styrene faciHties. Timing, or luck, is even more important because the supply and demand of styrene are seldom in balance and the price fluctuates broadly and rapidly as a result. Most of the time, the producers either suffer losses (1981—1985, 1991—1993) or enjoy handsome profits (1987—1990, 1994—mid-1995). Investments in styrene plants are known to have been recovered in less than a year, but prosperity encourages over-investment and lean years may foUow. 

Pipeline engineers use the flow value stated as standard cubic feet per day. This is an artificial weight flow because flowing conditions are referred to a standard pressure and temperature. The balance of the flow specification is then stated in tenns of specific gravity. 

Equation (14.83) gives us an estimate for the velocity c at various pipeline angles 5 when the corresponding values for vertical and horizontal lines are known. It is an estimate, of course, because its derivation was based on the force balance of a single particle and not on the balance of the mixture of particles as a whole. 

Some environmentalists anticipated a major accident like that of the Exxon Valdez. When plaiiiiing for the Trans-Alaska Pipeline took place during the energy crisis of the early 1970s, it was controversial because of the conflicts of balancing the needs of oil... 

Because of their role as the link between producing and market areas, interstate natural gas pipelines play a crucial role in balancing supply and demand. To do so, the interstate pipelines continually monitor pipeline performance. These companies rely heavily on computers to gather, analyze and retain information on the performance of their pipelines, and to control the flow of gas in remote sections of the line. 

If a fluid is to be pumped between two points, the diameter of the pipeline should be chosen so that the overall cost of operation is a minimum. The smaller the diameter, the lower is the initial cost of the line but the greater is the cost of pumping an economic balance must, therefore, be achieved. 

A homogeneous flow basis must be used when thermodynamic equilibrium is assumed. For furtl er simplification it is assumed there will be no reaction occurring in the pipeline. The vapor and liquid contents of the reactor are assumed to be a homogeneous mass as they enter the vent line. The model assumes adiabatic conditions in the vent line and maintains constant stagnation enthalpy for the energy balance. 

In Section II,C we have deliberately chosen a simple set of problem specifications for our steady-state pipeline network formulation. The specification of the pressure at one vertex and a consistent set of inputs and outputs (satisfying the overall material balance) to the network seems intuitively reasonable. However, such a choice may not correspond to the engineering requirements in many applications. For instance, in analyzing an existing network we may wish to determine certain input and output flow rates from a knowledge of pressure distribution in the network, or to compute the parameters in the network element models on the basis of flow and pressure measurements. Clearly, the specified and the unknown variables will be different in these cases. For any pipeline network how many variables must be specified And what constitutes an admissible set of specifications in... 

In principle, the steady-state pipeline network problems can always be solved by the transient solution methods after allowing sufficient time steps for the solution to reach steady state. This possibility was discussed by Nahavandi and Catanzaro (Nl) who made a comparison of a transient solution method with the Cross method of balancing flows (R4). For the particular 35-node and 45-branch hydraulic network problem tested, the transient solution method took 108 seconds as compared with the 134 seconds required by the Hardy-Cross method. (See also Section V,A,2.)... 

Sent and received transportation quantities are the basis to calculate transit inventories for the between and cross-period case. Transit inventory is the balance of carry-over or transit inventory from the previous period plus new sent transportation quantity minus received transportation quantity leaving the pipeline . 

The pressure Pq (Ibf/ft gauge) of inert gas behind the pig is essentially constant aU the way down the pipeline. The tank into which the liquid dumps is at atmospheric pressure. The pipeline is horizontal. A force balance in the horizontal z direction yields... 

Surface Tension Measurements. These were made with the Wilhclmy balance technique 1 The pipeline crude remained in contact with its own vapor throughout the measurements... 

A Network of Pipelines in Series, Parallel, and Branches the Sketch, Material Balances, and Pressnre Drop Eqnations... 

This case study illustrates how combinations of pipeline burial, insulation, heating, and methanol injection can be used to prevent hydrates. The selection of the hydrate prevention scheme(s) is then a matter of balancing capital against operating costs. 

A second objective was to provide a balance between hydrate experimental and theoretical perspectives. The monograph was intended as a single record of the majority of hydrocarbon thermodynamic data obtained since 1934, the time of discovery of hydrates in pipelines. The third edition, in particular, shows the transition away from thermodynamics to kinetics, as mankind learns to study more sophisticated, time-dependent phenomena. 

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