Engineering Flow Diagrams

The piping designer needs three essential source documents engineering flow diagrams, nomenclature, and equipment elevations. These documents are usually furnished by the piping analyst. 

Engineering flow diagrams contain a schematic flow of the process connecting the various items of equipment such as columns, exchangers, pumps, etc. They include all the information essential for the operation of the process. 

Engineering flow diagrams do not present all the essential information for the piping designer. They do not include equipment elevations and insulation specifications, which may be obtained from the equipment elevation summary and from the nomenclature list. 

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Figure 7-1 shows part of a typical engineering flow diagram. In addition to showing schematically the piping required, the engineering flow diagram also includes 1 the valves and control devices that will be required. 

On the average-size process plant engineering flow diagram, there are approximately 1,500 separate pipe lines. Information on each of these lines is absolutely necessary for the piping designer. The information that must be shown on each line includes the size, the line specification showing... 

Figure 7-1. Portion of typical Engineering Flow Diagram.

The engineering flow diagrams consist of various types. 

As a result of coordinating material, energy, and engineering flow diagrams, the design engineer is now in a position to select possible types of equipment which will do the job and obtain a cost estimate for each major item. The selection of process equipment will be discussed next in Chap. 4. 

Engineering flow diagram with required information ... 

Engineering flow diagrams (with line lists)... 

Prepare detailed engineering flow diagrams which form the basis of final plant design. 

The compressor can be driven by electric motors, gas or steam turbiaes, or internal combustion (usually diesel) engines. The compressor can also be a steam-driven ejector (Fig. 7b), which improves plant reUabiUty because of its simplicity and absence of moving parts, but also reduces its efficiency because an ejector is less efficient than a mechanical compressor. In all of the therm ally driven devices, turbiaes, engines, and the ejector mentioned hereia, the exhaust heat can be used for process efficiency improvement, or for desalination by an additional distillation plant. Figure 8 shows a flow diagram of the vertical-tube vapor compression process. 

Fig. 12. Lime spray dryer process flow diagram. Reproduced by permission of the American Institute of Chemical Engineers, 1991 (67).

Once the candidate corrective measure alternatives have been identified, a more detailed evaluation of each alternative needs to be undertaken. From an engineering perspective, the first step in the evaluation process would include the development of a conceptual design for each alternative. The conceptual design would consist of a process description, a process flow diagram and a layout drawing. Preliminary sizing of equipment and utility and land requirements would be developed. In addition, chemical requirements and residuals produced can be estimated. From the conceptual design, permitability and residuals disposal issues can be identified and addressed. 

Figure 4-11. Deep oatalytio oraoking prooess flow diagram. (Courtesy of Stone Webster Engineering Corporation, 1977 Stone Webster Engineering Corporation.)...

You can quickly identify these plant sections by reviewing process flow diagrams and valving arrangements. Isolation points are defined by control valves or powered block valves that can be remotely activated. Process hazard analysis techniques help you identify the maximum credible accident scenarios. (Note that manual valves should not be considered reliable isolation points unless they are located to be accessible following a major accident. However, remotely-activated valves can only be considered reliable isolation points if there are adequate reliability engineering and maintenance programs in place.)... 

Prepare/supervise preparation of piping or mechanical flow diagram (or P and ID), with necessary preliminary sizing of all pipe lines, distillation equipment, pumps, compressors, etc., and representation of all instrumentation for detailing by instrument engineers. 

Basic flow diagrams should be available and, if not, the commissioning engineer must draw them up, against which actual plant performance can be checked. (See Figure 32.1.)... 

FIGURE 28.5 Flow diagram of the selected treatment system. (From Eroglu, V. and Erturk, F., in Handbook of Industrial Waste Treatment, Wang, L.K. and Wang, M.H.S., Eds, Marcel Dekker, New York, 1991, pp. 293-306 Eroglu, V., Topacik, D., and Ozturk, I., Wastewater Treatment Plant for Cayirova Pipe Factory, Environmental Engineering Department, Istanbul Technical University, Turkey, 1989. With permission.)... 

Figure 1- 1 Flow Diagram for Armour s Soap Plant. Courtesy of Ladyn, H. W., Fat Splitting and Soap Making Go Continuous, Chemical Engineering Aug. 17, 1964, p. 106.

Figure 3.45 Schematic flow diagram. (From Kopalinsky and Bryant, 1976. Copyright 1976 by American Institute of Chemical Engineers, New York. Reprinted with permission.)...

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