Rules


These rules are both necessary and sufficient to ensure that the target is achieved, providing the initialization rule is adhered to that no individual heat exchanger should have a temperature difference smaller than  [c.169]

In design, the same rules must be obeyed around a utility pinch as around a process pinch. Heat should not be transferred across it by process-to-process transfer, and there should be no inappropriate use of utilities. In Fig. 6.13a this means that the only utility to be used above the utility pinch is steam generation and only cooling water below. In Fig. 6.136 this means that the only utility to be used above  [c.173]

Having decided that no exchanger should have a temperature difference smaller than ATmi, two rules were deduced. If the energy target set by the composite curves (or the problem table algorithm) is to be achieved, there must be no heat transfer across the pinch by  [c.364]

Figure 16.13 The CP inequality rules can necessitate stream splitting above the pinch. Figure 16.13 The CP inequality rules can necessitate stream splitting above the pinch.
Figure 16.14 The CP inequality rules can necessitate stream splitting below the pinch. Figure 16.14 The CP inequality rules can necessitate stream splitting below the pinch.
Following the pinch rules, there should be no heat transfer across either the process pinch or the utility pinch by process-to-process heat exchange. Also, there must be no use of inappropriate utilities. This means that above the utility pinch in Fig. 16.17a, high-pressure steam should be used and no low-pressure steam or cooling water. Between the utility pinch and the process pinch, low-pressure steam should be used and no high-pressure steam or cooling water. Below the process pinch in Fig. 16.17, only cooling water should be used. The appropriate utility streams have been included with the process streams in Fig. 16.17a.  [c.381]

The network can now be designed using the pinch design method.The philosophy of the pinch design method is to start at the pinch and move away. At the pinch, the rules for the CP inequality and the number of streams must be obeyed. Above the utility pinch and below the process pinch in Fig. 16.17, there is no problem in applying this philosophy. However, between the two pinches, there is a problem, since designing away from both pinches could lead to a clash where both meet.  [c.381]

A good initialization for heat exchanger network design is to assume that no individual exchanger should have a temperature difference smaller than AT n. Having decided that no exchanger should have a temperature difference smaller than two rules were deduced in  [c.396]

Fajans rules Ionic compounds are most readily formed by  [c.172]

Hund s rules Rules which describe the electronic configuration of degenerate orbitals in the ground state. The electronic configuration will have the maximum number of unpaired  [c.207]

Groups attached to the chiral centre are given an order of priority according to the sequence rules. For an enantiomeric carbon compound the group of lowest priority is  [c.288]

This spectrum is called a Raman spectrum and corresponds to the vibrational or rotational changes in the molecule. The selection rules for Raman activity are different from those for i.r. activity and the two types of spectroscopy are complementary in the study of molecular structure. Modern Raman spectrometers use lasers for excitation. In the resonance Raman effect excitation at a frequency corresponding to electronic absorption causes great enhancement of the Raman spectrum.  [c.340]

However, the rules governing method selection can be given  [c.108]

When the conductivities of each component have been determined, the conductivity of the mixture is obtained by the rules set forth by Li in 1976  [c.135]

For the refiner, the main problem is to meet the specifications for kinematic viscosity and sulfur content. Dilution by light streams such as home-heating oil and LCO, and selection of feedstocks coming from low-sulfur crude oils give him a measure of flexibility that will nevertheless lead gradually to future restrictions, most notably the new more severe antipollution rules imposing lower limits on sulfur and nitrogen contents.  [c.241]

The main justification for diesel fuel desulfurization is related to particulate emissions which are subject to very strict rules. Part of the sulfur is transformed first into SO3, then into hydrated sulfuric acid on the filter designed to collect the particulates. Figure 5.21 gives an estimate of the variation of the particulate weights as a function of sulfur content of diesel fuel for heavy vehicles. The effect is greater when the test cycle contains more high temperature operating phases which favor the transformation of SO2 to SO3. This is particularly noticeable in the standard cycle used in Europe (ECE R49).  [c.254]

The accreditation of a standard is an official act (signed by the Ministry of Industry in France). To prepare standards, governments have mandated private organizations which are responsible for continuously following the rules to reach a mciximum consensus. There is only one such organization per country. They are, moreover, grouped at the European and international levels.  [c.295]

Mehrotra, A.K. (1990), Development of mixing rules for predicting the viscosity of bitumen and its fractions blended with toluene . Can. J. Chem. Eng., Vol. 68, p. 839.  [c.458]

The method allows variables to be added or multiplied using basic statistical rules, and can be applied to dependent as well as independent variables. If input distributions can be represented by a mean, and standard deviation then the following rules are applicable for independent variables  [c.168]

Having defined some of the statistical rules, we can refer back to our example of estimating ultimate recovery (UR) for an oil field development. Recall that  [c.169]

From the probability distributions for each of the variables on the right hand side, the values of K, p, o can be calculated. Assuming that the variables are independent, they can now be combined using the above rules to calculate K, p, o for ultimate recovery. Assuming the distribution for UR is Log-Normal, the value of UR for any confidence level can be calculated. This whole process can be performed on paper, or quickly written on a spreadsheet. The results are often within 10% of those generated by Monte Carlo simulation.  [c.169]

All the three techniques mentioned above may make use of fuzzy sets and fuzzy logic (for fuzzy classification, fuzzy rules or fuzzy matching) but this does not effect the discussion of the applicability to NDT problems in the next section.  [c.99]

Convergence of this iteration is influenced by initial estimates for the true mole fractions, zThe following rules have been found to lead to rapid convergence in all cases.  [c.135]

Porter, K. E., and Momoh, S. O., Finding the Optimum Sequence of Distillation Columns—An Equation to Replace the Rules of Thumb (Heuristics), Chem. Engg. J., 46 97, 1991.  [c.157]

The maximum temperature cross which can be tolerated is normally set by rules of thumb, e.g., FrSQ,75 °. It is important to ensure that Ft > 0.75, since any violation of the simplifying assumptions used in the approach tends to have a particularly significant effect in areas of the Ft chart where slopes are particularly steep. Any uncertainties or inaccuracies in design data also have a more significant effect when slopes are steep. Consequently, to be confident in a design, those parts of the Ft chart where slopes are steep should be avoided, irrespective of Ft 0.75.  [c.223]

These rules are both necessary and sufficient for the design to achieve the energy target, given that no individual exchanger should have a temperature difference smaller than ATmin- To comply with these two rules, the process should therefore be divided at the pinch. As pointed out in Chap. 6, this is most clearly done by representing the stream data in the grid diagram. Figure 16.1 shows the stream data from Table 6.2 in grid form with the pinch marked. Above the pinch, steam can be used (up to and below the pinch, cooling water  [c.364]

The pinch design method developed earlier followed several rules and guidelines to allow design for minimum utility (or maximum energy recovery) in the minimum number of units. Occasionally, it appears not to be possible to create the appropriate matches because one or other of the design criteria cannot be satisfied.  [c.372]

These rules are both necessary and sufficient for the design to achieve the energy target, given that no individual exchanger should have a temperature difference smaller than ATnin-  [c.396]

Crum Brown s rule A guide to substitution in benzene derivatives. This rule states that a substance C Hj A yields the meia disubstituied product if the compound HA can be oxidized directly to HOA otherwise a mixture of the o-and p-compounds will be obtained. Not universally applicable.. Sec Hammick and Illingworth s rules.  [c.116]

For ketoximes, the group which is syn or anti to the hydroxyl group must be specified. Difficulty in assigning the terms cis and trans arises when there is no pair of identical, or similar, groups substituting an alkene. Then the terms (E) [German entgegen = slCTOSs] and (Z) [German zusammen = together] replace the terms iransjcis. In many cases, but not all, the term cis corresponds to (Z) and trans to (E). Under this new system the two ligands attached to each olefinic carbon atom are put in order of precedence by application of sequence rules and the symbols (E) and (Z) are then used to describe those isomers in which the ligands of higher precedence are on the opposite side (E), etc. Maleic acid is then referred to as the (Z)-isomer and fumaric acid  [c.225]

The Superplus with its RON and MON greater than or equal to 98 and 88 respectively. These two values do not correspond to official specifications but to quality specification sheets drawn up by French auto manufacturers. Strictly according to the rules, Superplus is only a variety of a top quality Eurosuper.  [c.198]

These products are used for motor scooters, outboard motors and other engines for domestic use such as power mowers and chain saws equipped with spark-ignition two-stroke engines. Their design will require either a conventional fuel, if the lubrication is separate, or mixtures of fuel and lubricating oil, with 2 to 6% oil depending on the manufacturer s specifications. In the latter case, up to now, the oil is mixed with regular gasoline containing lead. Yet, this will soon disappear. Its replacement by other products like conventional premium, Eurosuper, and Superplus will not present many particular problems concerning combustion however, certain problems of engine failure due to insufficient lubrication have been brought to light. Currently the rules covering this area are not directed toward two-stroke engines, which would be unrealistic considering their limited market, but towards a more rigorous and better adapted lubricant specifications. Under these conditions, the two-stroke engine fuel that will be recommended worldwide will very likely be a conventional unleaded premium fuel like Eurosuper.  [c.231]

Management of decommissioning costs is an issue that most companies have to face at some time. On land sites, wells can often be plugged and processing facilities dismantled on a phased basis, thus avoiding high spending levels just as hydrocarbons run out. Offshore decommissioning costs can be very significant and less easily spread as platforms cannot be removed in a piecemeal fashion. The way in which provision is made for such costs depends partly on the size of the company involved and on the prevailing tax rules.  [c.8]

Management of the cost of decommissioning is an issue that most companies have to face at some time. The cost can be very significant, typically 10% of the cumulative capex for the field. On land sites, wells can often be plugged and processing facilities dismantled on a phased basis, thus avoiding high spending levels just as hydrocarbons run out. Offshore decommissioning costs can be very significant and less easily spread as platforms cannot be removed in a piecemeal fashion. How provision is made for such costs depends partly on the size of the company involved and the prevailing tax rules.  [c.367]

Expert systems. Expert systems solve problems by doing reasoning using a set of if..then rules [Giarrtano Riley, 1989]. The rules are usually written by a knowledge engineer after the knowledge has been acquired fiom a domain expert in a series of knowledge acquisition sessions. The input to an expert system consists of a set of facts describing problem to be solved. The facts are processed using the rules which may assert new facts. If no new facts are present or the solution has been reached the reasoning stops.  [c.99]

Expert systems. In situations where the statistical classifiers cannot be used, because of the complexity or inhomogeneity of the data, rule-based expert systems can sometimes be a solution. The complex images can be more readily described by rules than represented as simple feature vectors. Rules can be devised which cope with inhomogeneous data by, for example, triggering some specialised data-processing algorithms.  [c.100]


See pages that mention the term Rules : [c.132]    [c.350]    [c.395]    [c.200]    [c.200]    [c.200]    [c.252]    [c.354]    [c.356]    [c.426]    [c.427]    [c.228]    [c.100]    [c.101]    [c.101]   
Gas turbine engineering handbook (2002) -- [ c.0 ]