Explain

Whether heat integration is restricted to the separation system or allowed with the rest of the process, integration always benefits from colder reboiler streams and hotter condenser streams. This point is dealt with in more general terms in Chap. 12. In addition, when column pressures are allowed to vary, columns with smaller temperature differences are easier to integrate, since smaller changes in pressure are required to achieve suitable integration. This second point is explained in more detail in Chap. 14. 

There is a tradeoff between energy and capital cost i.e., there is an economic degree of energy recovery. Chapter 7 explains how this tradeoff can be carried out using energy and capital cost targets. 

The preceding appropriate placement arguments assume that the process has the capacity to accept or give up the reactor heat duties at the given reactor temperature. A quantitative tool is needed to assess the capacity of the background process. For this purpose, the grand composite curve can be used and the reactor profile treated as if it was a utility, as explained in Chap. 6. 

The logic behind these three evolutions is explained in Chap. 5. 

Debye-Hiickel theory The activity coefficient of an electrolyte depends markedly upon concentration. Jn dilute solutions, due to the Coulombic forces of attraction and repulsion, the ions tend to surround themselves with an atmosphere of oppositely charged ions. Debye and Hiickel showed that it was possible to explain the abnormal activity coefficients at least for very dilute solutions of electrolytes. 

Defines over 2,000 literary terms (including lesser known, foreign language and technical terms) explained with illustrations from literature past and present. 

An extraordinary document which explains with eloquence and passion how we should go about the care and maintenance of a small planet . 

All have molecular weights of 226 to the nearest integer (C = 12, H = 1, S = 32), but the exact molecular weights differ slightly. A resolution of 2500 is necessary to separate molecules 1, 2 and 3 but 75,000 is required to separate molecule 4 from molecule 3 which explains why high resolution mass spectrometers are sdiiglit. 

For many years the development of refining processes and the formulation of gasolines has centered around the octane number. It is therefore appropriate to explain briefly what is the current situation and what are the prospects in this area. 

The two numbers each have their own utility which explains why both are taken into account when setting specifications. Nevertheless, in the context of refining today, it is the minimum MON that is the most difficult constraint for the refiner. For example, to obtain an 85 MON for Eurosuper it often happens that the RON is greater than 95 in actual practice it is 96 or even 97. Likewise, Superplus can represent, for an 88 MON, an RON of 99 or 100. 

In the past, reducing the sulfur content was mainly concerned with the heaviest products, most particularly the fuel oils. This development is explained by a legitimate concern to reduce SO2 emissions, notably in areas around large population centers. This is how low sulfur heavy fuels —having a maximum of 2% sulfur— and very low sulfur ( % sulfur) came into being. Currently the whole range of petroleum products, particularly motor fuels, should be strongly desulfurized for reasons we will explain hereafter. 

However, such a level can still be considered too high for vehicles having 3-way catalytic converters. In fact, results observed in the United States (Benson et al., 1991) and given in Figure 5.20 show that exhaust pollutant emissions, carbon monoxide, hydrocarbons and nitrogen oxides, increase from 10 to 15% when the sulfur level passes from 50 ppm to about 450 ppm. This is explained by an inhibiting action of sulfur on the catalyst though... 

These reactions can explain the absence of olefins in crude oil, their presence being detected only in the crudes of low sulfur content. The sulfur content in crude from Bradford which is the one of the rare crudes containing olefins is about 0.4%. 

The following sections will explain in more detail the terms introduced so far. 

Four mechanisms have been suggested to explain how faults provide seals. The most frequent case is that of clay smear and juxtaposition (Fig. 5.8)... 

The fluids contained within petroleum accumulations are mixtures of organic compounds, which are mostly hydrocarbons (molecules composed of hydrogen and carbon atoms), but may also include sulphur, nitrogen, oxygen and metal compounds. This section will concentrate on the hydrocarbons, but will explain the significance of the other compounds in the processing of the fluids. 

Alkanes from CH to C4gFlg2 typically appear in crude oil, and represent up to 20% of the oil by volume. The alkanes are largely chemically inert (hence the name paraffins, meaning little affinity), owing to the fact that the carbon bonds are fully saturated and therefore cannot be broken to form new bonds with other atoms. This probably explains why they remain unchanged over long periods of geological time, despite their exposure to elevated temperatures and pressures. 

Figure 5.21 helps to explain how the phase diagrams of the main types of reservoir fluid are used to predict fluid behaviour during production and how this influences field development planning. It should be noted that there are no values on the axes, since in fact the scales will vary for each fluid type. Figure 5.21 shows the relative positions of the phase envelopes for each fluid type. 

The diagram (Fig. 5.21) shows that as the pressure is reduced below the dew point, the volume of liquid in the two phase mixture initially increases. This contradicts the common observation of the fraction of liquids in a volatile mixture reducing as the pressure is dropped (vaporisation), and explains why the fluids are sometimes referred to as retrograde gas condensates. 

The above equation introduces two new properties of the oil, the formation volume factor and the solution gas oil ratio, which will now be explained. 

In a reservoir at initial conditions, an equilibrium exists between buoyancy forces and capillary forces. These forces determine the initial distribution of fluids, and hence the volumes of fluid in place. An understanding of the relationship between these forces is useful in calculating volumetries, and in explaining the difference between free water level (FWL) and oil-water contact (OWC) introduced in the last section. 

The benefit of using the decision tree approach is that it clarifies the decision-making process. The discipline required to construct a logical decision tree may also serve to explain the key decisions and to highlight uncertainties. 

Prior to the calculation of tax, certain allowances may be made against the gross revenue before applying the tax rate. These are called fiscal costs and commonly include the royalty, opex and capital allowances (which is explained later in this section). Fiscal costs may also be referred to as deductibles. 

The relationship between the tubing performance and reservoir performance is more fully explained in Section 9.5. 

The analysis of the test results shows that non-defect adhesive joints of the carbon plastic are acoustically less active than the glued main material. This can be explained by absence of plasticization effect of the die (adhesive layer). The value of the breaking point ("C ) at the adhesive joints shift is 9,6 M Pa. 

Often the a priori knowledge about the structure of the object under restoration consists of the knowledge that it contains two or more different materials or phases of one material. Then, the problem of phase division having measured data is quite actual. To explain the mathematical formulation of this information let us consider the matrix material with binary structure and consider the following potentials ... 

The sampling precision of the measured data depends on the signal amplitude. The difference between simulated and experimental data can be mainly explained by the low numerical precision of the measured data. 

The comparison between measured data and simulated data are good for the imaginary part, but differences appear for the real part. The ratio between simulated data and measured data is about 0.75 for TRIFOU calculation, and 1.33 for the specialised code. Those differences for the real part of the impedance signal can be explained because of the low magnitude of real part compared to imaginary part signal. 

It enables first to explain the phenomena that happen in the thin-skin regime concerning the electromagnetic skin depth and the interaetion between induced eddy eurrent and the slots. Modelling can explain impedance signals from probes in order to verify experimental measurements. Parametric studies can be performed on probes and the defect in order to optimise NDT system or qualify it for several configurations. 

The diffraction of the incident 45°-S V -transducer-pulse at the interface between the isotropic steel and the anisotropic weld may result in two transmitted qSV-wavefronts, a particular phenomenon to be explained with pertinent slowness diagrams. 

Second corner reflection The first corner reflection appears as usual when the transducer is coupled to the probe at a certain distance from the V-butt weld. The second corner reflection appears if the transducer is positioned well above the V-hutt weld. If the weld is made of isotropic material the wavefront will miss (pass) the notch without causing any reflection or diffraction (see Fig. 3(a)) for this particular transducer position. In the anisotropic case, the direction of the phase velocity vector will differ from the 45° direction in the isotropic case. Moreover, the direction of the group velocity vector will no longer be the same as the direction of the phase velocity vector (see Fig. 3(b), 3(c)). This can be explained by comparing the corresponding slowness and group velocity diagrams. 

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