CEV 602 DESIGN PROJECT
CHAPTER 1
Diagrams for Understanding
Chemical Processes
FACULTY OF CHEMICAL ENGINEERING
UiTM PULAU PINANG
3 Levels of Diagram
Block Flow Diagram (BFD)
Process Flow Diagram (PFD)
Piping and Instrumentation Diagram (P&ID)
often referred to as Mechanical Flow Diagram
Complexity Conceptual
increases understanding
Increases
As chemical engineers, we are most familiar
with BFD and PFD.
The Block Flow Diagram (BFD)
BFD shows overall processing picture of a
chemical complex
Flow of raw materials and products may be
included on a BFD
BFD is a superficial view of facility ChE
information is missing
Definitions of BFD
Block Flow Process Diagram
Figure 1.1
Similar to sketches in material and energy
balances
Block Flow Plant Diagram
Figure 1.2
Gives a general view of a large complex plant
The Block Flow Process Diagram
The Block Flow Plant Diagram
The Process Flow Diagram
PFD shows all process engineering
information
Diagram developed in junior year
design projects (especially the 2nd
semester)
Often PFD is drawn on large paper
textbook breaks down information
into 1 diagram and 2 tables
The Process Flow Diagram (Contd.)
The topology of the process showing the
connectivity of all the streams and the
equipment.
Example for toluene HDA Figures 1.3 and 1.5
Tables 1.2 and 1.4 list information that
should be on the PFD but cannot fit
Use appropriate conventions consistency is
important in communication of process
information. ex. Table 1.2
The Process Flow Diagram (Contd.)
The Process Flow Diagram (Contd.)
Equipment Numbering
XX-YZZ A/B/
XX represents a 1- or 2-letter designation for
the equipment (P = pump)
Y is the 1 or 2 digit unit number (1-99)
ZZ designates the equipment number for
the unit (1-99)
A/B/ represents the presence of spare
equipment
Equipment Numbering (Contd.)
Thus, T-905 is the 5th tower in unit nine
hundred P-301 A/B is the 1st Pump in unit three
hundred plus a spare
Use unambiguous letters for new equipment
Ex. Turbine use Tb or J not T (for tower)
Replace old vessel V-302 with a new one of
different design - use V-319 (say) not V-302
since it may be confused with original V-
302
Stream Numbering and Drawing
Number streams from left to right as much as
possible
Horizontal lines are dominant
Stream Numbering and Drawing (Contd.)
Add arrows for :
Change in direction
Inlet of equipment
Utility streams should use convention given in
Table 1.3, lps, cw, fg, etc.
Stream Information
Since diagrams are small, not much stream
information can be included
Include important data around reactors and
towers, etc.
Flags are used see toluene HDA diagram
Full stream data, as indicated in Table 1.4, are
included in a separate flow summary table
see Table 1.5
Stream Information - Flags
The Process Flow Diagram (contd)
The Process Flow Diagram (contd)
Basic Control Loops
Often the basic control loops (those involving
maintaining material balance and reactor
controls) are included on the PFD;
instrumentation and other control loops are not
shown
Basic Control Loops
Equipment Information
Equipment are identified by number and a label
(name) positioned above the equipment on the
PFD
Basic data such as size and key data are
included in a separate table (Equipment
Summary Table) Table 1.7 (and Table 1.6) in
TBWS
Equipment Information
PFD Summary
PFD, Equipment Summary Table, and Flow
Summary Table represent a true PFD
This information is sufficient for a preliminary
estimation of capital investment (Chapter 7)
and cost of manufacture (Chapter 8) to be
made
The Piping and Instrument Diagram(P&ID)
P&ID Construction Bible
Contains: plant construction information
(piping, process, instrumentation, and other
diagrams)
P&ID information is explained in Tables 1.8 and
1.9
Conventions for instrumentation are shown in
Figure 1.10
(P&ID)
Look at V-102 on P&ID
V-102 contains an LE (Level Element)
LE senses liquid level in separator and adjusts
flow rate leaving
LE opens and closes a valve depending on liquid
level
LE and valve represent a feedback control loop
Other Common Diagrams
Plot Plans plan or map drawn looking down
on plant (drawn to scale with all major
equipment identified)
Elevation Diagrams show view from side and
give information about equipments distance
from ground
Other Common Diagrams
Other Common Diagrams (Contd)
Piping Isometrics show piping in 3-dimensions
Vessel Sketches show key dimensions of
equipment and locations of inlet and outlet
nozzles etc.
Scale Models and Virtual Plants
25 years ago physical models were used for
review
Now virtual or electronic models are generated
using software (3-d plant diagrams)
Purpose of Models catch errors such as :
Piping clashes
Misaligned piping
Equipment not easily accessed
Sample points not easily reached by
operators
END OF CHAPTER 1
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