Flow-sheet presentation

As the process flow-sheet is the definitive document on the process, the presentation must be clear, comprehensive, accurate and complete. The various types of flow-sheet are discussed below. 

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In Europe, the German standards organisation has published a set of guide rules and symbols for flow-sheet presentation, DIN 28004 (1988). This is available in an English translation from the British Standards Institution. 

A better method for the presentation of data on flow-sheets is shown in Figure 4.2. In this method each stream line is numbered and the data 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 flow-sheet is shown in Figure 4.3. Guide rules for the layout of this type of flow-sheet presentation are given in Section 4.2.5. 

The flow sheet presented here has been shown, in laboratory tests using mixer-settlers, to be suitable for separating the the three actinides, Th, U and Pu from each other. 

The objective of this effort was the initial recovery of Sc with subsequent process steps to separate and recover the other metallic constituents. The initial step was the acid digestion of the tungsten ore tailings, which produced an insoluble residue containing W and a solution rich in most of the other metals. The steps in the overall separation scheme are outlined by the flow sheet presented in Figure 3. The hydrazine/ sulfuric acid solution was chosen as the reductant/solvent reagent based on the following considerations ... 

The process flow sheet presented in Figure 32.10 provides the minimum information that should be given. Very often, additional information is implemented in the form of a rectangle with four different values, for example, pressure, enthalpy, mass flow, and temperature. The orientation, together with the units used, should also be shown in the diagram. As an example, the conflguration with the highest... 

The unit has virtually the same flow sheet (see Fig. 2) as that of methanol carbonylation to acetic acid (qv). Any water present in the methyl acetate feed is destroyed by recycle anhydride. Water impairs the catalyst. Carbonylation occurs in a sparged reactor, fitted with baffles to diminish entrainment of the catalyst-rich Hquid. Carbon monoxide is introduced at about 15—18 MPa from centrifugal, multistage compressors. Gaseous dimethyl ether from the reactor is recycled with the CO and occasional injections of methyl iodide and methyl acetate may be introduced. Near the end of the life of a catalyst charge, additional rhodium chloride, with or without a ligand, can be put into the system to increase anhydride production based on net noble metal introduced. The reaction is exothermic, thus no heat need be added and surplus heat can be recovered as low pressure steam. 

A simplified flow sheet depicting the process used in New Mexico is presented in Figure 5. 

Specify the chemical components present ia the streams of the flow sheet. 

Various techniques are available to separate the different types of particles that may be present in a sohd mixture. The choice depends on the physicochemical nature of the sohds and on site-specific considerations (for example, wet versus diy methods). A key consideration is the extent of the liberation of the individual particles to be separated. Particles attached to each other obviously cannot be separated by direct mechanical means except after the attachment has been broken. In ore processing, the mineral values are generally liberated by size reduction (see Sec. 20). Rarely is liberation complete at any one size, and a physical-separation flow sheet wih incorporate a sequence of operations that often are designed first to rejec t as much... 

Once a decision has been made to recover materials and/or energy, process flow sheets must be developed for the removal of the desired components, subject to predetermined materials specifications. A typical flow sheet for the recovery of specific components and the preparation of combustible materials for use as a fuel source is presented in Fig. 25-63. The light combustible materials are often identified as refuse-derived fuel (RDF). 

Complex Flow Sheets Operating plants do not consist of single flashes, neat exchangers, distilfation towers, or reac tors. As the number of pieces of eqmpment increases within the unit under study, the reconciliation becomes more difficult. For example. Fig. 30-21 presents a more comphcated, three-module unit. 

Data on spare and parallel equipment are often omitted. Valving is also generally omitted. A alve is shown only where its specification can aid in understanding intermittent or alternate flows. Instrumentation is indicated to show the location of variables being controlled and the location of the actuating device, usually a control valve. To help the reader better understand the process flow sheet, a list of commonly used symbols is presented in Fig. 5.9.1. 

The production rate of acetic acid was 2kg-h 1, where the maximum acetic acid concentration was 12%. Air was pumped into the fermenter with a molar flow rate of 200 moMi-. The chemical reaction is presented in (E. 1.1) and flow diagram in Figure 9.5. Determine the minimum amount of ethanol intake and identify the required mass balance for the given flow sheet. The ethanol biochemical oxidation reaction using A. aceti is ... 

It is reported that between 10 and 11 million cars are taken apart every year in North America once the metallic portion has been recovered from the crushing operation, the remainder - representing over 20% of the total mass or 3.5 million tons - must be eliminated. Pyrovac, in collaboration with Universite Laval and under the sponsorship of E.T.P. Technologies, recently undertook a research programme to recover valuable products from this Automobile Shredder Residue. A process flow sheet for a 4000 kg/hr plant is presented, with fixed capital investment estimated to be 5 million US dollars. Details are given. 

This chapter covers the preparation and presentation of the process flow-sheet. The flowsheet is the key document in process design. It shows the arrangement of the equipment selected to carry out the process the stream connections stream flow-rates and compositions and the operating conditions. It is a diagrammatic model of the process. 

The material balance is presented on a block flow sheet so that the reader can graphically visualize what is happening. An example is given in Figure 4E- 1. Each major operation appears as a block. No attempt is made to identify the specific pieces of equipment or to size them. The blocks are interconnected with flow lines, which indicate for each substance where it enters the process, what path it follows, and where it is eventually discharged. These flow lines are keyed to a chart that gives the composition and amount of each stream in the form of a unit ratio material balance. A material balance should be given for each product made by a multipurpose plant. 

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