CHAPTER III
MANUFACTURING PROCESS
Figure 3.1 Flowchart of Manufacturing Power-Free
Refrigerator
A process flow diagram (PFD)
is a diagram commonly used in chemical and process engineering to indicate
the general flow of plant processes and equipment.
The PFD displays the relationship between major equipment of a plant facility
and does not show minor details such as piping details and designations.
Another commonly used term for a PFD is a flowsheet.
Process flow diagram symbols and elements – are provided from
various online sources with recommended links below.
1.https://en.wikipedia.org/wiki/Process_flow_diagram#:~:text=A%20process%20flow%20diagram%20(PFD,as%20piping%2
0details%20and%20designations.
2. https://www.lucidchart.com/pages/process-flow-diagrams
ISO 10628-- graphical symbols for the preparation of diagrams for the chemical and petrochemical industry at
https://commons.wikimedia.org/wiki/File:ISO_10628-2_2012_Symbols_Sheet_3.svg
 Flowsheet drafting programs: professional edition of Microsoft Visio™ contains a library of PFD icons
 Specification for graphical symbols for general engineering. Part 1: Piping systems and plant
Information to be Included on Process Flowsheet
The amount of information shown on a flowsheet will depend on the custom and practice of the particular design
office. The list given below has therefore been divided into essential items and optional items. The essential items
must always be shown; the optional items add to the usefulness of the flowsheet but are not always included.
Essential Information
1. Always show all process equipment, including feed and product storage and
equipment used for
transporting fluids and solids.
2. Always indicate the location of process control valves.
3. Stream composition, either
i. tabulate the flow rate of each individual component, kg/h, which is preferred,
or
ii. give the stream composition as a weight fraction.
4. Total stream flow rate, kg/h.
5. Stream temperature, degrees Celsius preferred.
6. Nominal operating pressure (the required operating pressure).
7. Stream enthalpy, kJ/h.
Optional Information
1. Molar percentage composition and/or molar flow
rates.
2. Physical property data, mean values for the stream,
such as
i. density, kg/m3,
ii. viscosity, mN s/m2.
3. Stream name, a brief, one- or two-word description
of the nature of the stream, for example
“ACETONE COLUMN BOTTOMS,”
Guide rules for the layout of this type of flowsheet presentation
a) The sequence of the main equipment items shown symbolically on the flowsheet follows that of the
proposed plant layout (2D plant lay-out).
 The aim should be to show the flow of material from stage to stage as it will occur, and to give a general
impression of the layout of the actual process plant.
b) The equipment should be drawn approximately to scale, such as such as reactors, vessels, and columns
should be drawn roughly in the correct proportion. Ancillary items can be drawn out of proportion. For a
complex process, with many process units, several sheets may be needed, and the continuation of the
process streams from one sheet to another must be clearly shown.
 Line continuation is indicated with a double concentric circle around the line number and the continuation
sheet number is written below. An alternative method is to extend lines to the side of the page and then indicate the
drawing sheet on which the line is continued.
c) The equipment should be well spaced out so that streams can be labeled without the drawing becoming
cluttered. It is better to use several continuation sheets than to try to fit everything on one page.
 Line continuation is indicated with a double concentric circle around the line number and the continuation sheet
number is written below. An alternative method is to extend lines to the side of the page and then indicate the drawing
sheet on which the line is continued.
d) The table of stream flows and other data can be placed above or below the equipment layout. Normal
practice is to place it below.
 The components should be listed down the left-hand side of the table, as in Figures 2.8 and 2.9. For a long table,
it is good practice to repeat the list at the right-hand side, so the components can be traced across from either side.
e) The stream line numbers should follow consecutively from left to right of the layout, as far as is practicable,
so that when reading the flowsheet it is easy to locate a particular line and the associated column containing
the data.
f) All the process stream lines shown on the flowsheet should be numbered and the data for the
stream given.
 On a large flowsheet, the designers sometimes use different series of numbers for different plant sections; for
example beginning the stream numbering at 100 for feed preparation, 200 for reaction, 300 for separation, and 400 for
purification.
g) Each piece of equipment shown on the flowsheet must be identified with a code number and name. The
identification number (usually a letter and some digits) is normally that assigned to a particular piece of
equipment as part of the general project control procedures, and is used to identify it in all the project
documents.
 The easiest code is to use an initial letter to identify the type of equipment, followed by digits to identify the
particular piece: for example, H—heat exchangers, C—columns, and R—reactors.
The purpose of the flowsheet is to show the function of each process
unit, even when the function has no discernible impact on the mass
and energy balance.
The simplest method, suitable for simple processes with few pieces of equipment, is to
tabulate the data in blocks alongside the process stream lines.
A better method for the presentation of data on flowsheets
 each stream line is numbered and the data are tabulated at the bottom of the sheet
A typical commercial
flowsheet
Figure 20.1 Flowsheet of a modern brick and roof tile manufacturing plant.
Fig. 9.26. Glass production processes. Raw feedstocks include sand (primarily), soda ash, and
limestone; cullet is recycled glass from previously used material and broken glass in the production
process. Melting and refining are the most energy intensive phases of production.
Figure 3.2 Process Flow Sheet for the Production of Power –Free Ceramic Pot Coolers
Narrative of the process
Production design/description
Quality control/Packaging
Production volume