Preliminaries

Preliminary. Before World War 1, little was known either about the nature of X-rays (were they like waves or more like particles ) or about the 

Such flashes, inspirations if you like, do not happen while one is thinking in one s study or talking with a student. They turn up like a photograph in the mind at some odd time later (Leo Szilard, for example, got some of his best ideas while soaking in the bathtub). But they don t turn up at all unless one has thought a great deal about the matter. 

Shortly after von Laue s suggestion and its validation, Bragg produced his equation. He showed that conditions for interference would be reached when 

---

If distillation is the choice of separator, then some preliminary selection of the major design variables must be made to allow the design to proceed. The first decision is operating pressure. As pressure is raised,... 

Example 4.5 Given that a low rate of production is required, convert the continuous process from Example 4.4 into a batch process. Preliminary sizing of the equipment indicates that the duration of the processing steps are given in Table 4.7. ... 

Preliminary process optimization is greatly simplified, as will be seen in the next chapter. 

In preliminary process design, the primary consideration is contact by inhalation. This happens either through accidental release of toxic material to the atmosphere or the fugitive emissions caused by slow leakage from pipe flanges, valve glands, and pump and compressor seals. Tank filling causes emissions when the rise in liquid level causes vapor in the tank to be released to the atmosphere. 

Both the reboiling and condensing processes normally take place over a range of temperature. Practical considerations, however, usually dictate that the heat to the reboiler must be supplied at a temperature above the dew point of the vapor leaving the reboiler and that the heat removed in the condenser must be removed at a temperature lower than the bubble point of the liquid. Hence, in preliminary design at least, both reboiling and condensing can be assumed to take place at constant temperatures. ... 

Process economics have three basic roles in preliminary process... 

Preliminary process optimization. Dominant process variables such as reactor conversion can have a major influence on the design. Preliminary optimization of these dominant variables is often required. 

To evaluate design options and carry out preliminary process optimization, simple economic criteria are required. What happens to the revenue from product sales after the process has been commissioned The sales revenue first pays for fixed costs which are independent of the rate of production. Variable costs, which do depend on the rate of production, also must be met. After this, taxes are deducted to leave the net profit. 

Two simple economic criteria are useful in preliminary process design ... 

In preliminary process design it mig] it be necessary to use marginal costs for steam, but the designer should keep in mind the dangers of using such costs. 

The cost of the capital depends on its source. The source of the capital often will not be known during the early stages of a project, and yet there is a need to select between process options and carry out preliminary optimization on the basis of both capital and operating costs. This is difficult to do unless both capital and operating costs can be expressed on a common basis. Capital costs can be expressed on an annual basis if it is assumed that the capital has been borrowed over a fixed period (usually 5 to 10 years) at a fixed rate of interest, in which case the capital costs can be annualized according to... 

Lang, H. J., Cost Relationships in Preliminary Cost Estimation, Chem. Engg., 54 117, 1947. 

Guthrie, K. M., Data and Techniques for Preliminary Capital Cost Estimating, Chem. Engg., 76 114, 1969. 

In order to simplify the analysis of petroleum and its fractions, other preliminary separation techniques are employed, aiming generally to separate certain classes of components. 

Analysis of such cuts by spectrometry requires a preliminary separation by chemical constituents. The separation is generally done by liquid phase chromatography described in article 3.3.5. 

As the temperatures of the distillation cuts increase, the problems get more complicated to the point where preliminary separations are required that usually involve liquid phase chromatography (described earlier). This provides, among others, a saturated fraction and an aromatic fraction. Mass spectrometry is then used for each of these fractions. 

This is an analysis frequently conducted on oil lubricants. Generally, the additive is known and its concentration can be followed by direct comparison of the oil with additive and the base stock. For example, concentrations of a few ppm of dithiophosphates or phenols are obtained with an interferometer. However, additive oils today contain a large number of products their identification or their analysis by IR spectrometry most often requires preliminary separation, either by dialysis or by liquid phase chromatography. 

In this case, a preliminary separation will have taken place either in the plant by stabilization, or by the chromatograph which will have had a prefractionating column. This column will isolate the components having boiling points higher than pentane, allowing only the noncondensable hydrocarbons and a fraction of the pentanes to pass through to the analytical column. 

If a sand line (0% shale) and a shale line (100% shale) are defined on the gamma ray log, a cut-off limit of 50% shale can be used to differentiate the reservoir from non-reservoir intervals. This type of cut-off is often used in preliminary log evaluations and is based on the assumption that reservoir permeability is destroyed once a rock contains more than 50% shale. 

For example a process flow scheme for crude oil stabilisation might contain details of equipment, lines, valves, controls and mass and heat balance information where appropriate. This would be the typical level of detail used in the project definition and preliminary design phase described in Section 12.0. 

Definition and Preliminary Design Detailed Design Procurement Construction Commissioning Review... 

After preliminary shop tests on different mockups (e.g. superheater and reheater headers and steamline pipe sections), since 1996 AEBIL systems have been installed and are at work on several power plant components. In particular, three different components have been monitored throughout 1997 (monitoring still under way at the time being) ... 

Preliminary in-field applications have also confirmed the successful long-term performance of the AEBIL instrumentation in power plant environment. 

Finally, preliminary diagnostic evaluation criteria, based on preventive identification of critical areas of interest on the monitored item, spatial concentration of localized AE events as compared with average AE event density and evolution of local event concentration vs time and/or plant parameters, have been worked out and submitted to extensive testing under real operation conditions. Work on this very critical issue is still to be consohdated. 

The Zond VD - 96 is intended for the detection of cracks, precipitates, inclusions etc. and corrosive defects with the preliminary estimation of their depth in various objects of magnetic and non - magnetic steels, non-ferrous and refractory metals and welds including coatings. 

The inspection possibility of welds and rough surfaces also under the coating of various foulings, oils, scale, rust etc. without the preliminary preparation. 

There are difficulties of detecting defects in axial canal because of solid sediment layer of 1. 2 mm thick on the canal surface. When using known defectoscope devices a preliminary labor-intensive mechanical treatment of the axial canal surface is needed. The experience of application of different methods of rotor axial canal control in multifunction automatic device ROTOR - K has pointed to the fact that the most effective method is eddy current one [1]. All the dangerous cracks were just detected by the eddy current method, the part of the cracks were not... 

---