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All too often safety and health (and environmental) considerations are left to the final stages of the design. Returning to the hierarchy of design illustrated by the onion diagram in Fig. 1.6, such considerations would add another layer in the diagram outside the utilities layer. This approach leaves much to be desired. 

The use of an unnecessarily hot utility or heating medium should be avoided. This may have been a major factor that led to the runaway reaction at Seveso in Italy in 1976, which released toxic material over a wide area. The reactor was liquid phase and operated in a stirred tank (Fig. 9.3). It was left containing an uncompleted batch at around 160 C, well below the temperature at which a runaway reaction could start. The temperature required for a runaway reaction was around 230 C. ... 

As with safety, environmental considerations are usually left to a late stage in the design. However, like safety, early decisions often can lead to difficult environmental problems which later require complex solutions. Again, it is better to consider effluent problems as the design progresses in order to avoid complex waste treatment systems. 

Additional separation and recycling. Once the possibilities for recycling streams directly, feed purification, and eliminating the use of extraneous materials for separation that cannot be recycled efiiciently have been exhausted, attention is turned to the fourth option, the degree of material recovery from the waste streams that are left. One very important point which should not be forgotten is that once the waste stream is rejected, any valuable material turns into a liability as an effluent material. The level of recovery in such situations needs careful consideration. It may be economical to carry out additional separation of the valuable material with a view to recycling that additional recovered material, particularly when the cost of downstream effluent treatment is taken into consideration. 

Turning now to the cold-end design, Fig. 16.6a shows the pinch design with the streams ticked off. If there are any cold streams below the pinch for which the duties eu e not satisfied by the pinch matches, additional process-to-process heat recovery must be used, since hot utility must not be used. Figure 16.66 shows an additional match to satisfy the residual heating of the cold streams below the pinch. Again, the duty on the unit is maximized. Finally, below the pinch the residual cooling duty on the hot streams must be satisfied. Since there are no cold streams left below the pinch, cold utility must be used (Fig. 16.6c). 

Following this hierarchy, all to often safety, health and environmental considerations are left to the final stages of design. This approach leaves much to be desired, since early decisions made purely for process reasons often can lead to problems of safety, health, and environment that require complex solutions. It is better... 

PPha, pyridine) organic groups (olefines, aromatic derivatives) and also form other derivatives, e.g. halides, hydrides, sulphides, metal cluster compounds Compounds containing clusters of metal atoms linked together by covalent (or co-ordinate) bands, metaldehyde, (C2H40) ( = 4 or 6). A solid crystalline substance, sublimes without melting at I12 1I5" C stable when pure it is readily formed when elhanal is left in the presence of a catalyst at low temperatures, but has unpredictable stability and will revert to the monomer, ft is used for slug control and as a fuel. 

Ostwald ripeniDg A process of crystal growth in which a mixture of coarse and fine crystals of a substance are left in contact with a solvent. This results in a growth of the large crystals and the ultimate disappearance of the fine crystals. 

The absorbed light may act as calalv. i for a spontaneous reaction, but in other cases it may supply energy to make possible a reaction which, without light, would be thermodynamically impossible. In some cases, such a reaction reverses itselfby thermal reaction (e.g. if left in the dark) and, hence, during irradiation a phoiostationary state is reached. 

Raney nickel A special form of nickel prepared by treating an Al-Ni alloy with NaOH solution. The nickel is left in a spongy mass which is pyrophoric when dry. This form of nickel is a most powerful catalyst, especially for hydrogenations. 

I6I C. Warfarin baits need contain only 0 025% active principle, and rats are killed after ingesting about 5 doses the bait can be left down and the risk of acute toxicity to man or domestic animals is not serious. In common with other coumarin derivatives, warfarin reduces the clotting power of blood and death is caused by haemorrhages initiated by any slight injury. Warfarin is a vitamin K antagonist, and large oral doses of the vitamin can be given as an antidote. 

An important safety feature on every modern rig is the blowout preventer (BOP). As discussed earlier on, one of the purposes of the drilling mud is to provide a hydrostatic head of fluid to counterbalance the pore pressure of fluids in permeable formations. However, for a variety of reasons (see section 3.6 Drilling Problems ) the well may kick , i.e. formation fluids may enter the wellbore, upsetting the balance of the system, pushing mud out of the hole, and exposing the upper part of the hole and equipment to the higher pressures of the deep subsurface. If left uncontrolled, this can lead to a blowout, a situation where formation fluids flow to the surface in an uncontrolled manner. 

Particularly for jack-up rigs, site surveys may have to be carried out prior to each reemployment to ensure that the rig is positioned away from the previously formed footprints (depressions on the sea-bed left by the jack-up legs on a previous job). 

Once the bubble point is reached (at point B), the first bubble of ethane vapour is released. From point B to C liquid and gas co-exist in the cell, and the pressure is maintained constant as more of the liquid changes to the gaseous state. The system exhibits infinite compressibility until the last drop of liquid is left In the cell (point C), which is the dew point. Below the dew point pressure only gas remains in the cell, and as pressure is reduced below the dew point, the volume increase is determined by the compressibility of the gas. The gas compressibility is much greater than the liquid compressibility, and hence the change of volume for a given reduction in pressure (the... 

Moving back to the overall picture, it can be seen that as the fraction of ethane in the mixture changes, so the position of the two-phase region and the critical point change, moving to the left as the fraction of the lighter component (ethane) increases. 

Figure 5.34 Photograph of core (left = normal light, right = UV)...

The tree is drawn by starting with the first decision to be taken, asking which actions are possible, and then considering all possible results from these actions, followed by considering future actions to be taken when these results are known, and so on. The tree is constructed in chronological order, from left to right. 

Figure 8.13 indicates a number of situations in which oil is left in the reservoir, using a water drive reservoir as an example. 

Unstable displacement is clearly less preferable, since a mixture of oil and water is produced much earlier than in the stable displacement situation, and some oil may be left unrecovered at the abandonment condition which may be dictated by a maximum water cut. 

Miscible processes are aimed at recovering oil which would normally be left behind as residual oil, by using a displacing fluid which actually mixes with the oil. Because the miscible drive fluid is usually more mobile than oil, it tends to bypass the oil giving rise to a low macroscopic sweep efficiency. The method is therefore best suited to high dip reservoirs. Typical miscible drive fluids include hydrocarbon solvents, hydrocarbon gases, carbon dioxide and nitrogen. 

When a production or injection well is drilled, it is common practice to cement in place a casing which extends across the reservoir interval. The alternative is to leave the reservoir uncased, in a so-called bare foot completion, which is rarely done. When the drilling department finishes its work on the well, it is often left in the state of a cased hole, as on the left of Figure 9.14. 

The data gathered from the logs and cores of the development wells are used to refine the correlation, and better understand areal and vertical changes in the reservoir quality. Core material may also be used to support log data in determining the residual hydrocarbon saturation left behind in a swept zone (e.g. the residual oil saturation to water flooding). 

Attic / cellar oil may be left behind above (or below) production wells... 

All pipelines will be circulated clean and those that are buried, or on the seabed, left filled with water or cement. Surface piping will normally be cut up and removed. Flexible subsea pipelines may be reeled-in onto a lay barge and disposed of onshore. 

The 45° transducer was used to inspect side drilled holes, with their centres located 40 mm below the surface. Due to the coarse material structure the echoes from the holes were totally masked by clutter. An example of an ultrasonic response signal, emanating from a hole with a diameter of 8 mm, is shown in the left part of Figure 3. Scanning the surface above the 8 mm and 10 mm holes resulted in the B-scan image shown in the upper part of Figure 4. 

Fig. 3. One simulated projection of the simulated object with different level of noise (left column) a) 0.0, b) 0.05, c) 0.1, d) 0.15, and the corresponding restored images (right column) using 5 projections.

Figure 7 V-butt weld with perpendicular grain orientation and an inclination of the interface of 15° left without, right with backwall breaking notch...

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