Planting depth

The underground portion of the stem represents the site for rhizome development and, in many instances, the formation of lateral branches. The length of this portion of the stem depends on the planting depth of the seed tubers shallow planting is undesirable. Swanton (1986) found that the dry weight of the underground stem was substantially higher in cultivated clones (35.3 g) than in wild clones (16.2 g). 

In the two cases described in Table 2, there are basically no major chemical methods of selective weed control for controlling these grass weeds in wheat. The few herbicides that control these grasses also kill wheat. The only chemical methods available would be herbicides with placement selectivity. Such herbicides can be used in only certain soil types and the planting depth of wheat must be carefully controlled. 

The control of carbon dioxide emission from burning fossil fuels in power plants or other industries has been suggested as being possible with different methods, of which sequestration (i.e., collecting CO2 and injecting it to the depth of the seas) has been much talked about recently. Besides of the obvious cost and technical difficulties, this would only store, not dispose of, CO2 (although natural processes in the seas eventually can form carbonates, albeit only over very long periods of time). 

The fourth level of defense-in-depth is activated if all of the previous levels fail and radioactivity is released from the power-generating system. This level consists of containment systems and accident management processes that prevent the dissernination of radioactivity to the atmosphere even if it is released from the nuclear systems. The fifth level is the provision for emergency planning outside the plant boundary in the highly unlikely event that all of the first four levels of defense were to fad. 

The safety principles and criteria used ia the design and constmction of the faciUties which implement the nuclear fuel cycle are analogous to those which govern the nuclear power plant. The principles of multiple barriers and defense-ia-depth are appHed with rigorous self-checking and regulatory overview (17,34). However, the operational and regulatory experience is more limited. 

Geochemical Stage. The conversion of peat to bituminous coal is the result of the cumulative effects of temperature and pressure over a long time. The sediment covering the peat provides the pressure and insulation so that the earth s internal heat can be appUed to the conversion. The temperature increase is about 4 to 8°C for each 100 m of depth. The changes in plant matter are termed normal coalification. 

Continuously operated, small-scale or pilot-plant thickeners, ranging from 75 mm diameter by 400 mm depth to several meters in diameter, are also effectively used for sizing hill-scale equipment. This approach requires a significantly greater volume of sample, such as... 

The depth of cut involved in precoat filtration is a veiy important economic factor. There is some disagreement as to the method required to accurately predic t the minimum permissible depth of cut. Some investigators maintain that the depth of cut can be evaluated only in a quah-tative manner during bench-scale tests by judging whether the process solids remain on the surface of the precoat beck This being so, they indicate that it is necessaiy to run a continuous pilot-plant test to determine the minimum permissible depth of cut. The use of a continuous pilot-plant filter is a veiy desirable approach and will provide accurate information under a variety of operating conditions. 

However, it is not always possible to run a pilot-plant test in order to determine the depth of cut. A well-accepted alternative approach makes use of the more sophisticated test leaf illustrated in Fig. 18-97. This test leaf is designed so that the cake and precoat are extruded axially out the open end of the leaf. The top of the retaining wall on this end of the leaf is a machined surface which serves as a support for a... 

Typical pilot-plant top-suspended baskets are 305 mm (12 in) diameter by 127 mm (5 in) deep. Commercial machines are available in sizes from 508-mm (20-in) diameter by 305-mm (l2-in) depth to 1524-mm (60-in) diameter by 1016-mm (40-in) depth and develop up to 1800g in the smaller and intermediate sizes. Except in the sugar apphcation, operation with a two-speed motor (half speed for loading and full speed for purging) is typical. Hydraulic drives with variable-speed capability are commonly used in the chemical industiy To maximize the number of cycles per hour, a combination of electrical and mechanical braking is employed to minimize the deceleration period, which is a transition period of no value to the process. 

Specifications include dimensions of length, width, and depth, in that order (Fig. 21-40 ). When boxes are set up and closed by automatic equipment, dimensional tolerances become critical. Cartons are shipped knocked down to the user from plants located in all industrial centers. Because order lead time is 4 to 6 weeks, inventories of empty boxes require considerable space. A useful booklet describing all aspects or corrugated box designs and materials is the Fiber Box Handbook available from The Fiber Box Association, 2850 Gulf Road, Rolling Meadows, IL 60008. 

Many operating data for carbonate plants are cited by Kohl and Riesenfeld (Gn.s Purification, Gulf, 1985) but not including tower heights. Pilot plant tests, however, are reported on 0.10- and 0.15-m (4- and 6-in) columns packed to depths of 9.14 m (30 ft) of Raschig rings hy Benson et al. (Chem. Eng. Prog., 50, 356 [1954]). 

In the primary binary loop, production wells recover 170°C hot water from the geothermal reservoir and deliver 3,036 m /lir at 14 bar to heat exchangers in the power plant. Water leaves the heat exchangers at 70-90°C and is recycled to the ground through a re-injection well at a depth of 400-600 m. In the secondary binary loop, the heat from the hot water evaporates the isobutane working fluid at 36 bar and 150°C (Table 4-2). 

It is very important to form a base line for the entire power plant. This would enable the operator to determine if the seetion of the plant is operating below design eonditions. The following performanee eurves should be obtained either from the manufaeturer or during aeeeptanee testing so that the in-depth study of the parameters and their interdependeney with eaeh other ean be defined ... 

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