1. The most effective way of communicating information about a process is through the use of flow diagrams.
Block Flow Diagram (BFD)
Process Flow Diagram (PFD)
Piping and Instrumentation Diagram (P&ID)

2. Three Levels of Representation
Block Flow Diagram (BFD)
Process Flow Diagram (PFD)
Piping and Instrumentation Diagram (P&ID) – often referred to as Mechanical Flow Diagram
Complexity
Conceptual understanding
Chemical engineers are most familiar with BFD and PFD.

3. Block flow diagram (BFD) for the production of benzene
Mixed Gas
(2,610 kg/h)
Toluene
(10,000 kg/h)
Reactor
Gas
Separator
Benzene
(8,210 kg/h)
Hydrogen
(820 kg/h)
Conversion
75% Toluene
Mixed Liquids
Toluene
Reaction : C7H8 + H2 = C6H6 + CH4
Block flow diagram (BFD) for the production of benzene
Toluene and hydrogen are converted in a reactor to produce benzene and methane.
The reaction does not go to completion, and excess toluene is required.
The non-condensable gases are separated and discharged.
The benzene product and the unreacted toluene are then separated by distillation.
The toluene is then recycled back to the reactor and the benzene removed in the product stream.

4. Conventions and format recommended for laying out a block flow diagram (BFD)
1. Operations shown by blocks.
2. Major flow lines shown with arrows giving direction of flow.
3. Flow goes from left to right whenever possible.
4. Light stream (gases) toward top, while heavy stream (liquids and solids) toward
bottom.
5. Critical information unique to process supplied.
6. If lines cross, then the horizontal line is continuous and the vertical line is broken.
7. Simplified material balance provided.

5. Process Flow Diagram (PFD)
C6H5CH3+H2  C6H6 + CH4

6. Process Flow Diagram (PFD)
A PFD includes the following items:
major equipment;
principal flow route and control involved from raw material feed to final product;
key temperature and pressure corresponding to anticipated normal operation;
material flow rates and compositions;
design duties and sizes of major equipment.

7. 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

8. The Process Flow Diagram (cont’d)
Conventions Used for Numbering Process Equipment
Process Equipment
General Format XX-YZZ A/B
XX are the identification letters for the equipment classification
C - Compressor or Turbine
E - Heat Exchanger
H - Fired Heater
P - Pump
R - Reactor
T - Tower
TK - Storage Tank
V - Vessel
Y designates an area within the plant
ZZ are the number designation for each item in an equipment class
A/B identifies parallel units or backup units not shown on a PFD
Additional description of equipment given on top of PFD
R. Turton and J. A. Shaeiwitz - Copyright 2008

9. Equipment Numbering (cont’d)
T-905: the 5th tower in unit 900
P-301 A/B: the 1st Pump in unit 300 plus a spare
Use unambiguous letters for new equipment
Ex. Turbine use Tb or J not T (used for tower)
Replace old vessel V-302 with a new one of different design –
use V-319 (e.g.) not V-302 – since it may be confused with original V-302

10. Equipment
Drawing

11. 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)

12. Equipment Information
Equipment Summary Table
Vessel
V-101
V-102
Temperature (ºC) 55 38
Pressure (bar)
2.0 24
Orientation
Horizontal
Vertical
MOC CS
Size
Height/Length (m)
5.9
3.5
Diameter (m)
1.9
1.1
Internals
s.p. (splash plate)

13. Stream Numbering and Drawing
Number streams from left to right as much as possible
Horizontal lines are dominant
yes no no

14. Stream Numbering and Drawing (cont’d)
Add arrows for
Change in direction
Inlet of equipment
Utility streams should use convention, e.g. lps, cw, fg, etc.

15. 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 are included in a separate flow summary table

16. Stream Information - Flags
R. Turton and J. A. Shaeiwitz - Copyright 2008

17. Process Streams Mass flow rate:0.82 tonne/h Temp.: 25oC
Pressure: 25.5 bar

18. Utility Streams
Note that utilities are not considered in the input-output structure since they are not (usually) process streams. Utilities for pumps and compressors are usually electricity and are not shown on the PFD.

19. The Process Flow Diagram (cont’d)
Flow Summary Information
Essential Information
Stream Number
Temperature (°C)
Pressure (bar)
Vapor Fraction
Total Mass Flow Rate (kg/h)
Total Mole Flow Rate (kmol/h)
Individual Component Flow Rates (kmol/h)
Optional Information
Component Mole Fractions
Component Mass Fractions
Individual Component Flow Rates (kg/h)
Volumetric Flow Rates (m3/h)
Significant Physical Properties
Density
Viscosity
Other
Thermodynamic Data
Heat Capacity
Stream Enthalpy
K-values
Stream Name
R. Turton and J. A. Shaeiwitz - Copyright 2008

20. The Process Flow Diagram (cont’d)
The Process Flow Diagram (cont’d)
Simplified Flow Summary Table
Stream Number 1 2 3 4 5 6 7 8 9 10
Temperature (°C) 25 59
225 41
600 38
654 90
Pressure (bar)
1.90
25.8
25.5
25.2
25.0
23.9
24.0
2.6
Vapor Fraction
0.0
1.00
1.0
Mass Flow(tonne/h)
10.0
13.3
0.82
20.5
6.41
0.36
9.2
20.9
11.6
Mole Flow(kmol/h)
108.7
144.2
301.0
1204.4
758.8
42.6
1100.8
1247.0
142.2
Component Mole Flow (kmol/h)
Hydrogen
286.0
735.4
449.4
651.9
652.6
0.02
Methane
15.0
317.3
302.2
16.95
438.3
442.3
0.88
Benzene
7.6
6.6
0.37
9.55
116.0
106.3
Toluene
143.2
144.0
0.7
0.04
1.05
36.0
35.0
R. Turton and J. A. Shaeiwitz - Copyright 2008

21. 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

22. 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 and operating cost to be made.

23. Conventions Used for Identifying Process Equipment
Process Equipment General Format XX-YZZ A/B
XX are the identification letters for the equipment
classification
C - Compressor or Turbine
E - Heat Exchanger
H - Fired Heater
P - Pump
R - Reactor
T - Tower
TK - Storage Tank
V - Vessel
Y designates an area within the plant
ZZ are the number designation for each item in an
equipment class
A/B identifies parallel units or backup units not
shown on a PFD
Supplemental Information Additional description of equipment given on top
of PFD

24. Conventions for Identifying Process and Utility Streams
Process Streams
All conventions shown in the first table (conventions for BFD) apply.
Diamond (square) symbol located in flow lines.
Numerical identification (unique for that stream) inserted in diamond (square).
Flow direction shown by arrows on flow lines.
Utility Streams
lps Low Pressure Steam: 3-5 barg (sat)‡
mps Medium Pressure Steam: barg (sat)‡
hps High Pressure Steam: barg (sat)‡
htm Heat Transfer Media (Organic): to 400C
cw Cooling Water: From cooling tower 30C returned at less than 45C+
wr River Water: From river 25C returned at less than 35C
rw Refrigerated Water: In at 5C returned at less than 15C
rb Refrigerated Brine: In at -45C returned at less than 0C
cs Chemical Waste Water with high COD
ss Sanitary Waste Water with high BOD, etc.
el Electric Heat (specify 220, 440, 660V service)
ng Natural Gas
fg Fuel Gas
fo Fuel Oil
fw Fuel Water
‡These pressure are set during the preliminary design stages and typical values vary within the ranges
shown.
+Above 45C, significant scaling occurs.

25. Information Provided in a Flow Summary
Essential Information
Stream Number
Temperature (C)
Pressure (bar)
Vapor Fraction
Total Mass Flow Rate (kg/h)
Total Mole Flow Rate (kmol/h)
Individual Component Flow Rates (kmol/s)
Optional Information
Component Mole Fractions
Component Mass Fractions
Individual Component Flow Rates (kg/h)
Volumetric Flow Rates (m3/h)
Significant Physical Properties
Density
Viscosity
Other
Thermodynamic Data
Heat Capacity
Stream Enthalpy
K-values
Stream Name

26. Equipment Descriptions for PFD and P&ID
Equipment Type
Description of Equipment
Towers
Size (height and diameter), Pressure, Temperature
Number and Type of Trays
Height and Type of Packing
Materials of Constructions
Heat Exchangers
Type: Gas-Gas, Gas-Liquid, Liquid-Liquid, Condenser, Vaporizer
Process: Duty, Area, Temperature, and Pressure for both streams.
No. of shell and Tube Passes
Materials of Construction: Tubes and Shell
Tanks
See vessels
Vessels
Hight, Diameter, Orientation, Pressure, Temperature, Materials of Construction
Pumps
Flow, Discharge Pressure, Temperature, P, Driver Type, Shaft Power, Materials of Construction
Compressors
Actual Inlet Flow Rate, Temperature, Pressure, DrverType, Shaft Power,
Materials of Construction
Heaters (fired)
Type, Tube Pressure, Tube Temperature, Duty, Fuel, Material of Construction
Others
Provide Critical Information

27. Piping and Instrumentation Diagram (P&ID)

28. 管線儀控圖 (P&ID - Piping & Instrumentation Diagram)
060
管線儀控圖 (P&ID - Piping & Instrumentation Diagram)
管線儀控圖（ P & ID ）又稱為機械流程圖（ mechanical flow diagram , MFD ）。
它表示了此工廠在開車及操作時所有必須的資料，包含了管線、操作裝置、及儀控等設備，
因此又稱為工程流程圖（engineering flow diagram ）
管線儀控圖是基於上一小節所述之程序流程圖而來的，每一張程序流程圖都需要數張管線儀控圖的說明，用來解釋工廠設備安裝的情況，並由程序方法工程師與管線儀控工程師合力完成。

29. Piping and Instrumentation Diagram (P&ID)
All process equipment and piping required for start-up, shut-down, emergency and normal operation of the plant, including valves, blinds, etc.
An id number, an identifier of the material of construction, diameter and insulation requirements for each line.
Direction of flow.
Identification of main process and start-up lines.
All instrumentation, control and interlock facilities with indication of action on instrument air failure.
Key dimensions or duties of all equipment.
Operating and design pressures and temperatures for vessels and reactors.
Equipment elevations.
Set pressure for relief valves.
Drainage requirements.
Special notes on piping configuration as necessary, e.g. “gravity drainage.”

30. Conventions in Constructing Piping and Instrumentation Diagrams
For Equipment - Shown Every Piece Including
Spare units
Parallel units
Summary details of each unit
For Piping - Include All Lines Including Drains, Sample Connections and Specify
Size (use standard sizes)
Schedule (thickness)
Materials of construction
Insulation (thickness and type)
For Instruments - Identify
Indicators
Recorders
Controllers
Show instrument lines
For Utility - Indentify
Entrance utilities
Exit utilities
Exit to waste treatment facilities

31. 管線儀控圖 (P&ID - Piping & Instrumentation Diagram)
060
管線儀控圖 (P&ID - Piping & Instrumentation Diagram)
圖2.24是一個典型蒸餾塔的管線儀控圖，因為此類圖中顯示的資料甚多，
故圖2.24只摘錄顯示出此蒸餾塔的上段部分。
除了程序裝置及流線外，還有許多圓圈型的符號、正方形內有圓形的符號、及一些折線，此是表示工廠中可量測到的資料，以及所使用的控制器。圓圈內編號以英文字母及五個數字組合而成，編號的第一個英文字母代表所量測的是何種資料，如 F 為流量、 P 為壓力、 L 為液位、 T 為溫度等。接著的英文字母中 A 代表警報（alarm）、I代表指示器（indicator）、 C 代表控制器（controller) , E 代表元件（element）、 S 代表開關（switch）、 T 代表轉換器（transmitter ）、 CV代表控制閥（ control valve）等。

32. THE NATURE OF PROCESS DESIGN A Creative Activity ！

33. Activities of Process Design
(1)Synthesis
The step where one conjectures the building blocks and their interconnections to create a structure which can meet the stated design requirements. structure
(2)Analysis (Simulation)
The activity of modeling and then solving the resulting equations to predict how a selected structure should behave if it were constructed.
(3)Evaluation
The activity of placing a worth on the structure where the worth might be its cost, its safety, or its net energy consumption.
(4)Optimization
The systematic searching over the allowed operating conditions to improve the evaluation as much as possible.
Parameter

34. Process Synthesis
A design task where one conjectures the building blocks and their interconnections to create a structure which can meet the stated design requirements.

35. 程序合成(Process Synthesis)是化工程序設計第一件要做的工作 。
所謂程序合成就是針對所要產製的化學品，尋找可利用的原料與反應路徑、選擇合適的單元操作設備及其組合，設計出能達到產能及產品規格的最佳化流程。
程序合成包括一連串尋找選擇與決定的過程，憑藉以往化學工程師的智慧與經驗法則(heuristic rules) ，建議出合理可行，且最符合經濟效益的化工程序，並交由下一階段的工程人員作細部的設備計算與設計，然後進行採購及建廠的後續工作。

36. Importance of Process Structure

37. Figure 1.1 (a) Synthesis is the creation of a process to transform feed streams into product streams. (b) Simulation predicts how it would behave if it was constructed.

38. 程序模擬(Process Simulation)
024
程序模擬(Process Simulation)
程序合成要做的工作，在給定產物的流率及產品純度規格下，要尋找出最合適的進料種類及條件，以及組合各單元操作設備的設計流程，以達成目的。

39. 程序模擬(Process Simulation)
024
程序模擬(Process Simulation)
程序模擬要做的工作，即是在進料種類及條件已知，以及設計流程及操作條件給定下，進行程序模擬的計算，目的是驗證程序合成結果的正確性。

40. 程序模擬(Process Simulation)
024
程序模擬(Process Simulation)
程序合成與程序模擬的工作是要反覆進行的，目的是使模擬結果符合產能及產品純度規格的要求。

41. An Example of Process Synthesis: Hydrodealkylation of Toluene

42. A Hierarchical Approach
Toluene + H2  Benzene + CH4
2 Benzene Diphenyl + H2
1150  F ～ 1300  F
500 psia

43. Toluene feed
ENERGY INTEGRATION

44. Alternatives?
Alternatives?

45. ALTERNATIVES OF DISTILLATION TRAIN
(1) Recycle Diphenyl
(2)
(3)

46. ALTERNATIVES OF VAPOR RECOVERY SYSTEM
(1) Condensation;
(2) Absorption;
(3) Adsorption;
(4) Membrane.

47. Simplified Flowsheet for Separation Systems
Design Alternatives?
Vapor recovery
system
Purge
H2 , CH4
H2 , CH4
Reactor
system
Phase
split
Toluene
Benzene
Liquid separation
system
Dipheny1
Simplified Flowsheet for Separation Systems

48. Recycle Structure of the Flowsheet
Gas recycle
Purge
H2 , CH4
Design Alternatives?
Benzene
H2 , CH4
Reactor
system
Separation
system
Toluene
Dipheny1
Toluene recycle
Recycle Structure of the Flowsheet

49. Input-Output Structure of the Flowsheet
Purge
H2 , CH4
H2 , CH4
Benzene
Toluene
Dipheny1
Input-Output Structure of the Flowsheet

50. Hierarchy of Decisions

51. Block Flow Process Diagram
Similar to sketches in material and energy balances
Output
Products
Input
Reactants
Excess toluene is required
Hydrodealkylation of toluene to produce benzene

52. Block Flow Diagram Similar to sketches in material and energy balances
Output
Products
Input
Reactants
Excess toluene is required
The benzene product and unreacted toluene are separated by distillation.
The noncondensable gases are separated and discharged
The toluene is recycled back to the reactor and the benzene removed in the product stream

53. Generic Structure of Process Flow Diagrams
Identify each equipment with one of the five blocks –
Purple – recycle, grey – reactor prep, flesh – reaction, green – separator prep, and green-grey - separation
C6H5CH3+H2  C6H6 + CH4

54. R. Turton and J. A. Shaeiwitz - Copyright 2008

55. R. Turton and J. A. Shaeiwitz - Copyright 2008
Basic Control Loops
R. Turton and J. A. Shaeiwitz - Copyright 2008

56. Exclusions from Piping and Instrumentation Diagram
1. Operating conditions T,P
2. Stream flows
3. Equipment locations
4. Pipe routing
a. Pipe lengths
b. Pipe fittings
5. Supports, structures, and foundations

57. Figure 1. 6 The “onion model” of process design
Figure 1.6 The “onion model” of process design. A reactor design in needed before the separation and recycle system can be designed, and so on. (From Smith and Linnhoff, Trans. IChemE, ChERD, 66:195, 1988; reproduced by permission of the Institution of Chemical Engineers.)
Reactor
Separation and
Recycle System
Heat Exchanger
Network
Utilities