Parting


Type B. Components 1 and 2 are only partly miscible with each other. Both 1 and 2 are completely miscible with all other components in the system (3 through m). Components 3 through m are also miscible in all proportions. Both binary and ternary data are needed for a reliable description of the multicomponent LLE  [c.74]

Generally speaking, temperature control in fixed beds is difficult because heat loads vary through the bed. Also, in exothermic reactors, the temperature in the catalyst can become locally excessive. Such hot spots can cause the onset of undesired reactions or catalyst degradation. In tubular devices such as shown in Fig. 2.6a and b, the smaller the diameter of tube, the better is the temperature control. Temperature-control problems also can be overcome by using a mixture of catalyst and inert solid to effectively dilute the catalyst. Varying this mixture allows the rate of reaction in different parts of the bed to be controlled more easily.  [c.56]

Not all problems have a pinch to divide the process into two parts. Consider the composite curves in Fig. 6.10a. At this setting, both steam and cooling water are required. As the composite curves are moved closer together, both the steam and cooling water requirements decrease until the setting shown in Fig. 6.106 results. At this setting, the composite curves are in alignment at the hot end,  [c.169]

Solution Figure 7.2 shows the stream grid with the pinch in place dividing the process into two parts. Above the pinch there are five streams, including the steam. Below the pinch there are four streams, including the cooling water. Applying Eq. (7.3),  [c.215]

There are parts of the flowsheet synthesis problem which can be solved without having to study actual designs. These are the layers of the process onion relating to the heat exchanger network and utilities. For these parts of the process design, targets can be set for energy costs and capital costs directly from the material and energy balance without having to resort to heat exchanger network design for evaluation.  [c.236]

The life cycle is first defined and the complete resource requirements (materials and energy) quantified. This allows the total environmental emissions associated with the life cycle to be quantified by putting together the individual parts. This defines the life-cycle inventory.  [c.295]

The stream data in Fig. 13.6 include those associated with the reactor and those for the rest of the process. If the placement of the reactor relative to the rest of the process is to be examined, those streams associated with the reactor need to be separated from the rest of the process. Figure 13.7 shows the grand composite curves for the two parts of the process. Figure 13.7b is based on streams 1, 2, 6, and 7 from Table 13.1, and Fig. 13.7c is based on streams 3, 4, 5, 8, 9, 10, and 11.  [c.335]

Figure 13.7 The problem can be divided into two parts, one associated with the reactor and the other with the rest of the process (AT i = 10°C), and then superimposed. Figure 13.7 The problem can be divided into two parts, one associated with the reactor and the other with the rest of the process (AT i = 10°C), and then superimposed.
In Chap. 6 it was discussed how the use of multiple utilities can give rise to multiple pinches. For example, the process from Fig. 6.2 could have used either a single hot utility or two steam levels, as shown in Fig. 6.26a. The targeting indicated that instead of using 7.5 MW of high-pressure steam at 240°C, 3 MW of this could be substituted with low-pressure steam at 180°C. Where the low-pressure steam touches the grand composite curve in Fig. 6.26a results in a utility pinch. Figure 16.17a shows the grid diagram when two steam levels are used with the utility pinch dividing the process into three parts.  [c.381]

The remaining problem analysis technique can be applied to any feature of the network that can be targeted, such as minimum area. In Chap. 7 the approach to targeting for heat transfer area [Eq. (7.6)] was based on vertical heat transfer from the hot composite curve to the cold composite curve. If heat transfer coefficients do not vary significantly, this model predicts the minimum area requirements adequately for most purposes. Thus, if heat transfer coefficients do not vary significantly, then the matches created in the design should come as close as possible to the conditions that would correspond with vertical transfer between the composite curves. Remaining problem analysis can be used to approach the area target, as closely as a practical design permits, using a minimum (or nea minimum) number of units. Suppose a match is placed, then its area requirement can be calculated. A remaining problem analysis can be carried out by calculating the area target for the stream data, leaving out those parts of the data satisfied by the match. The area of the match is now added to the area target for the remaining problem. Subtraction of the original area target for the whole-stream data Anetwork gives the area penalty incurred.  [c.387]

The total investment required for a project can be broken down into four parts  [c.415]

One particularly important property of the relationships for multipass exchangers is illustrated by the two streams shown in Fig. E.l. The problem overall is predicted to require 3.889 shells (4 shells in practice). If the problem is divided arbitrarily into two parts S and T as shown in Fig. El, then part S requires 2.899 and Part T requires 0.990, giving a total of precisely 3.889. It does not matter how many vertical sections the problem is divided into or how big the sections are, the same identical result is obtained, provided fractional (noninteger) numbers of shells are used. When the problem is divided into four arbitrary parts A, B, C, and D (Fig. E.l), adding up the individual shell requirements gives precisely 3.889 again.  [c.437]

As constituents of proteins the amino-acids are important constituents of the food of animals. Certain amino-acids can be made in the body from ammonia and non-nitrogenous sources others can be made from other amino-acids, e.g. tyrosine from phenylalanine and cystine from methionine, but many are essential ingredients of the diet. The list of essential amino-acids depends partly on the species. See also peptides and proteins.  [c.29]

Base, it stimulates all parts of the nervous system and in large doses produces convulsions. It is used for killing vermin.  [c.374]

Figure 6.9a shows a design corresponding to the flowsheet in Fig. 6.2 which achieves the target of Q/fmin = 5 MW and Qcmin = 10 MW for ATnjjn = 10°C. Figure 6.96 shows an alternative representation of the flowsheet, known as the grid diagram. The grid diagram shows only heat transfer operations. Hot streams are at the top running left to right. Cold streams are at the bottom running right to left. A heat exchange match is represented by a vertical line joining two circles on the two streams being matched. An exchanger using a hot utility is represented by a circle with a H. An exchanger using cold utility is represented by a circle with a C. The importance of the grid diagram is clear in Fig. 6.96, since the pinch, and how it divides the process into two parts, is easily accommodated. Dividing the process into two parts on a conventional diagram such as that shown in Fig. 6.9a is both difficult and extremely cumbersome.  [c.169]

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]

Figure 16.10 shows another threshold problem that requires only hot utility. This problem is different in characteristic from the one in Fig. 16.9. Now the minimum temperature difference is in the middle of the problem, causing a pseudopinch. The best strategy to deal with this type of threshold problem is to treat it as a pinched problem. For the problem in Fig. 16.10, the problem is divided into two parts at the pseudopinch, and the pinch design method is followed. The only complication in applying the pinch design method for such problems is that one-half of the problem (the cold end in Fig. 16.10) will not feature the flexibility offered by matching against utility. Figure 16.10 shows another threshold problem that requires only hot utility. This problem is different in characteristic from the one in Fig. 16.9. Now the minimum temperature difference is in the middle of the problem, causing a pseudopinch. The best strategy to deal with this type of threshold problem is to treat it as a pinched problem. For the problem in Fig. 16.10, the problem is divided into two parts at the pseudopinch, and the pinch design method is followed. The only complication in applying the pinch design method for such problems is that one-half of the problem (the cold end in Fig. 16.10) will not feature the flexibility offered by matching against utility.
Consider first the design for minimum energy in a more complex problem than seen so far. If the problem table analysis is performed on the stream data, Qnmiji and Qcmin can be calculated. When the network is designed and a match placed, it would be useful to assess whether there will be any energy penalty caused by some feature of the match without having to complete the design. Whether there will be a penalty can be determined by performing a problem table analysis on the remaining problem. The problem table analysis is simply repeated on the stream data, leaving out those parts of the hot and cold stream satisfied by the match. One of two results would then occur  [c.386]

All these fuel gases contain more than 50 % hydrogen and 10-30% methane, the other main components being CO, higher hydrocarbons, CO2 and Nj. In many parts of the world natural gas of calorific value of approximately 38MJ/m has become the widely-used gaseous fuel.  [c.401]


See pages that mention the term Parting : [c.26]    [c.132]    [c.154]    [c.294]    [c.318]    [c.383]    [c.383]    [c.385]    [c.396]    [c.9]    [c.10]    [c.18]    [c.23]    [c.37]    [c.43]    [c.54]    [c.90]    [c.96]    [c.105]    [c.129]    [c.138]    [c.150]    [c.190]    [c.195]    [c.206]    [c.297]    [c.297]    [c.302]    [c.313]    [c.322]    [c.340]    [c.372]   
The Nalco Guide to Cooling Water System Failure Analysis (1993) -- [ c.295 ]