Diagrams, flow

Stream Information. Directed arcs that represent the streams, with flow direction from left to right wherever possible, are numbered for reference. By convention, when streamlines cross, the horizontal line is shown as a continuous arc, with the vertical line broken. Each stream is labeled on the PFD by a numbered diamond. Furthermore, the feed and product streams are identified by name. Thus, streams 1 and 2 in Rgure 3.19 are labeled as the ethylene and chlorine feed streams, while streams 11 and 14 are labeled as the hydrogen chloride and vinyl-chloride product streams. Mass flow rates, pressures, and tempera-mres may appear on the PFD directly, but more often are placed in the stream table instead, for clarity. The latter has a column for each stream and can appear at the bottom of the PFD or as a separate table. Here, because of formatting limitations in this text, the stream table for the vinyl-chloride process is presented separately in Table 3.6. At least the following entries are presented for each stream label, temperature, pressure, vapor fraction, total and component molar flow rates, and total mass flow rate. In addition, stream properties such as the enthalpy, density, heat capacity, viscosity, and entropy, may be displayed. Stream tables are often completed using a process simulator. In Table 3.6, the conversion in the direct chlorination reactor is assumed to be 100%, while that in the pyrolysis reactor is only 60%. Furthermore, both towers are assumed to carry out perfect separations, with the overhead and bottoms temperatures computed based on dew- and bubble-point temperatures, respectively. 

Pyrolysis Quench Condenser HCl HCl Column HCl Column VC VC Column VC Column 

Furnace Tank Column Reflux Drum Condenser Column Condenser Reflux Drum 

Equipment Summary Table. This provides information for each equipment item in the PFD, with the kind of information typically provided for each type of unit shown in Table 3.8. Note that the materials of construction (MOC), and operating temperature and pressure, are required for all units. Also note that suggestions for the materials of construction are provided in Appendix III. 

Vessel Height, diameter, orientation, pressure, temperature, materials of constmction (MOC) 

This depends on fcls a0, and b0. Points of intersection of these two curves on the flow diagram correspond to conditions where R = L, and hence to stationary-state solutions. If R and L have just one intersection, as shown in Fig. 1.12(a) or (e), there is a unique stationary state. If L cuts R three times, as 

The jump points in Fig. 1.12(f) correspond to conditions where two stationary states come together and merge. In terms of the roots of the cubic equation, two real roots merge and become a complex pair. In terms of the flow diagram, the curves R and L become tangential. The two tangencies are represented in Figs 1.12(b) and (d). 

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Asphaltenes are obtained in the laboratory by precipitation in normal heptane. Refer to the separation flow diagram in Figure 1.2. They comprise an accumulation of condensed polynuclear aromatic layers linked by saturated chains. A folding of the construction shows the aromatic layers to be in piles, whose cohesion is attributed to -it electrons from double bonds of the benzene ring. These are shiny black solids whose molecular weight can vary from 1000 to 100,000. 

Figures 10.12 and 10.13 show, respectively, a flow diagram for lubricant oil production by hydrorefining and an integrated lubricating oil production unit using both extraction and hydrorefining.

Figure 10.17 presents a refinery flow diagram of the 1980s. 

Appraisal activity, if performed, is the step in the field life cycle between the discovery of a hydrocarbon accumulation and its development. The role of appraisal is to provide cost-effective information with which the subsequent decision can be made. Cost effective means that the value of the decision with the appraisal information is greater than the value of the decision without the information. If the appraisal activity does not add more value than its cost, then it is not worth doing. This can be represented by a simple flow diagram, in which the cost of appraisal is A, the profit (net present value) of the development with the appraisal information is (D2-A), and the profit of the development without the appraisal information is D1. 

One way of proceeding is shown in the flow diagram of figure 2 for the ease of = 8, P = 3. The operation labeled PERMUTE rearranges the sequence of data. The /th member is placed into theyth position where] is calculated from i as follows... 

Figure 2 Flow diagram of the DHT with N=8, P=3. Broken lines represent transfer factors -1 while full lines represent unity transfer factor. The crossover boxes perform the sign reversal called for by the shift theorem which also requires the sine and cosine factors Sn, Cn.

Figure C2.7.3. Process flow diagram for hydrofoniiylation of propene 4, stripping column 5, heat exchanger.

Dry-Process Hardboard. Dry-process hardboard is produced by a dry—dry system where dry fiber is formed iato mats, which are thea pressed ia a dry coaditioa. A flow diagram of this process is showa ia Figure 6. Ia this process, wood chips, sawdust, or other residues are refiaed to fiber ia pressurized refiners. Wax and PF resia may be added ia the refiner or ioimediately outside of the refiner, ia the fiber-ejectioa tube or "blowliae." It is also aoted that a small amouat of dry-process hardboard is made with UF resia biaders. UF resias, because of their inherent faster curing at lower temperatures, can be added only at the blowline or ia a bleader located after the dryer. 

Fig. 1. Process flow diagram of the commercial propylene ammoxidation process for acrylonitrile. BFW, boiler feed water.

Mild steel is a satisfactory constmction material for all equipment in Ziegler chemistry processes except for hydrolysis. If sulfuric acid hydrolysis is employed, materials capable of withstanding sulfuric acid at 100°C are requited lead-lined steel, some alloys, and some plastics. Flow diagrams for the Vista and Ethyl processes are shown in Eigures 3 and 4, respectively. 

Eig. 3. Flow diagram for the Vista Corporation primary alcohols plant. Lake Charles, Louisiana. 

Fig. 5. Flow diagram for oxo alcohol manufactured by the two-stage process. Courtesy of the Ethyl Corporation.

A typical flow diagram for pentaerythritol production is shown in Figure 2. The main concern in mixing is to avoid loss of temperature control in this exothermic reaction, which can lead to excessive by-product formation and/or reduced yields of pentaerythritol (55,58,59). The reaction time depends on the reaction temperature and may vary from about 0.5 to 4 h at final temperatures of about 65 and 35°C, respectively. The reactor product, neutralized with acetic or formic acid, is then stripped of excess formaldehyde and water to produce a highly concentrated solution of pentaerythritol reaction products. This is then cooled under carefully controlled crystallization conditions so that the crystals can be readily separated from the Hquors by subsequent filtration. 

Fig. 6. Energy flow diagram of a typical diaphragm ceU operation where numbers represent energy in millions of kilojoules per ton of chlorine. To convert...

Chlorine Plant Auxiliaries. Flow diagrams for the three electrolytic chlor—alkali processes are given in Figures 28 and 29. Although they differ somewhat in operation, auxiUary processes such as brine purification and chlorine recovery are common to each. 

Diaphragm process Fig. 28. Flow diagrams of the Mercury and Diaphragm chlor—alkah processes. 

Fig. 29. Flow diagram of the membrane chlor-alkah process...

Fig. 30. Flow diagram of a triple-effect caustic evaporator.

Trona Purification Processes. Two processes, named the monohydrate and sesquicarbonate according to the crystalline intermediates, are used to produce refined soda ash from trona. Both involve the same unit operations only in different sequences. Most ash is made using the monohydrate process. Eigure 2 shows simplified flow diagrams for each. 

Eig. 2. Simplified flow diagrams for soda ash from trona. 

Fig. 11. Flow diagram for the beater additive process. Kraft represents the kraft process wood pulp and NC is nitrocellulose used as starting materials...

The Eastman Chemicals from Coal faciUty is a series of nine complex interrelated plants. These plants include air separation, slurry preparation, gasification, acid gas removal, sulfur recovery, CO /H2 separation, methanol, methyl acetate, and acetic anhydride. A block flow diagram of the process is shown in Eigure 3. The faciUty covers an area of 2.2 x 10 (55 acres) at Eastman s main plant site in Kingsport, Teimessee. The air separation plant is... 

Fig. 3. Overall block flow diagram for Eastman s coal gasification—acetic anhydride complex (35).

A broad comparison of the main types of processes, the strength and quaUty of phosphoric acid, and the form and quaUty of by-product calcium sulfate are summarized in Table 7. Because the dihydrate process is the most widely used, the quaUty of its acid and calcium sulfate and its P2O3 recovery are taken as reference for performance comparisons. Illustrative flow diagrams of the principal variations in process types have been pubUshed (39). Numerous other variations in process details ar also used (40—42). The majority of plants use a dihydrate process and some of these have production capacity up to 2100 of P2O3 per day. 

The flow diagram for the viscose process is given in Figure 2. The sequence of reactions necessary to convert cellulose into its xanthate and dissolve it in soda used to be performed batchwise. Fully continuous processes, or mixtures of batch and continuous process stages, are more appropriate for high volume regular viscose staple production. 

Fig. 6. Simplified block flow diagram for the New Zealand gas-to-gasoline (GTG) plant (61). To convert m /h to gal/min, multiply by 4.40. HGT = heavy...

Fig. 7. A methanol-to-gasoline (MTG) fixed-bed process flow diagram. DME = dimethyl ether.

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