Flowsheet Presentation

As the process flowsheet is the definitive document on the process, the presentation must he clear, comprehensive, accurate, and complete. The various types of flowsheets are discussed in the following sections. 

Block diagrams are useful for representing a process in a simplified form in reports, textbooks, and presentations, but have only limited use as engineering documents. 

The stream flow rates and compositions can be shown on the diagram adjacent to the stream lines, when only a small amount of information is to be shown, or tabulated separately. 

Block diagrams are often drawn using simple graphics programs such as Visio or Microsoft PowerPoint.  

Only a limited amount of information can be shown this way, and it is difficult to make neat alterations or to add additional data. 

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Let us introduce a simple example to illustrate the previous concepts. The simplified process flowsheet presented in Fig. 1 (Madron, 1985) consists of four units interconnected by eight streams. We are interested in the estimation of the total flowrates of the system. If these variables are measured for streams 1, 7, and 8, then the measurement matrix C is of dimension (Z x g), where Z = 3 and g = 8. 

If the total flowrates of streams 1, 4, 7, and 8 are measured for the process flowsheet presented in Example 2.1, the matrix M is defined as follows ... 

As before, all the stream flowrates are assumed to be measured in the process flowsheet presented by Ripps (1965). The corresponding system matrix, A, and the covariance of the measurement errors, (P, are given in Section 10.3. 

The continuing decline in costs of graphical devices and the broadening availability of easy-to-use graphical software has made computer graphics a feasible tool in flowsheeting presentations and analysis (1 0 ). ... 

The above considerations lead to the conceptual flowsheet presented in Figure 8.5. Acid and alcohol enter countercurrently at the top and bottom of the reaction zone. The bottom product consisting of ester and some alcohol goes to an evaporator, from which the alcohol is recovered and recycled. The top vapor is condensed, and separated into two phases after decantation. The water leaves the decanter as a byproduct, while the alcohol-rich phase is sent as reflux into the column. 

A better method for the presentation of data on flowsheets is shown in Figure 4.2. In this method each stream line is numbered and the data are tabulated at the bottom of the sheet. Alterations and additions can be easily made. This is the method generally used by professional design offices. A typical commercial flowsheet is shown in Figure 4.3. Guide rules for the layout of this type of flowsheet presentation are given in Section 4.2.5. 

However, the two flowsheets presented here are simulated based on the general process design principles to closely resemble the actual processes. The two case studies should help the reader in understanding the difference in strategy in purifying intracellular and extracellular protein products. 

Qualitative flowsheets are given for the extraction and purification of all the rare metals discussed in earlier chapters. As far as possible the examples chosen are typical of current practice or of recently proposed processes. Each flowsheet presented begins with a mineral ore and ends with a pure metal, whereas in practice the various component operations are sometimes divided between two or more plants e.g. in the case of uranium, it is convenient to produce a concentrate containing about 70 per cent of the element near the minefield and to ship this to various refineries many thousands of miles away. Metal production may take place at the refinery, or in yet a third factory in association with subsequent metallurgical stages. 

Expand this example to evaluate the flowsheet presented in Chapter 3. 11.3.1.2 SO2 Catalytic Converter... 

The initial flowsheet presents a blank interface where we can place different objects from the Object palette shown in Figure 4.48. The initial tool palette only shows typical unit operations anddoesnot show the advanced Aspen HYSYS Petroleum Refining objects. We will use both toolbars to build the complete FCC model. We can bring up the advanced palette by pressing F6. 

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