Flow sheets

Flow sheetsMarch 2010

Cairo UniversityFaculty of EngineeringPetrochemicals Engineering

Lecture OutlineIntroductionBlock Flow Diagram (BFD)Process Flow Diagram (PFD)Piping and instrumentation Diagram (P&ID)Other Diagrams

IntroductionSketches and drawings are the engineer's own pictures. To describe a process, an engineer must:sketch equipment,show how they are interconnected, and show the process flows and operating conditionsTypes of flow sheets

2. Block Flow Diagram (BFD)At an early stage Provide an overview of a complex process or plantBlocks that represent individual processes or groups of operationsProperties1. Operations shown by blocks2. Major flow lines shown with arrows giving direction of flow3. Flow goes from left to right whenever possible4. Light stream (gases) toward top with heavy stream (liquids and solids) toward bottom5. Critical information unique to process supplied6. If lines cross, then the horizontal line is continuous and the vertical line is broken.7. Simplified material balance provided

Block Flow Diagram (BFD), cont.

Coal carbonization block flow diagram. Quantities are in lb/hr.

2. Block Flow Diagram (BFD), cont.

Pictorial flow diagram establishes key processing steps: Cement manufacturing

3. Process Flow Diagram (PFD)

Shows material and energy balances Shows major equipments of the plant. They include all vessels, such as reactors, separators, and drums; special processing equipment; heat exchangers; pumps; and so on.

3. Process Flow Diagram (PFD), cont.

Too much details will need a material and energy balance table

3. Process Flow Diagram (PFD), cont.

Process flow diagram of the manufacture of benzene by dealkylation of toluene.

3. Process Flow Diagram (PFD), cont.How to read a PFD?Equipment symbolsEquipment codesStream flags

3. Process Flow Diagram (PFD), cont.Equipment symbols

3. Process Flow Diagram (PFD), cont.Equipment Symbols

3. Process Flow Diagram (PFD), cont.Equipment Codes

3. Process Flow Diagram (PFD), cont.Equipment Codes

3. Process Flow Diagram (PFD), cont.Streams Flags

The use of flags must be for the important information only.Check streams (6) and (9) for temperature flags (they are hot streams)

3. Process Flow Diagram (PFD), cont.Example: Process Flow Diagram for the production of Benzene from TolueneProblem with E-102??

Where is E-102? What is E-102? What may be the problem? The effluent is mixture of liquid and gases, so the cooling is not efficient, beside the condensation problems.So??? Use two exchangers instead: E-10and E-10.., one for cooling and steam generation (reactor effluent boiler), and the second uses cooling water to reach the required temperature (reactor effluent condenser).

4- Piping and Instrumentation Diagram (P&ID)

The piping and instrumentation diagram (P&ID) or mechanical flow diagram (MFD) provides information needed by engineers to begin planning for the construction of the plant.

The P&ID is the last stage of process design and serves as a guide by those (?) who will be responsible for the final design and construction.

What not to include:1. Operating conditions T, P2. Stream flows3. Equipment locations4. Pipe routinga. Pipe lengthsb. Pipe fittings5. Supports, structures, and foundations

4- Piping and Instrumentation Diagram (P&ID), cont.What to include:

For EquipmentShow Every Piece (spare units, parallel units, summary details of each unit)For PipingInclude All Lines (drains, sample connections and specify size (use standard sizes), materials of construction, insulation (thickness and type)For InstrumentsIdentify indicators, recorders, controllersFor UtilitiesIdentify entrance utilities, exit utilities, exit to waste treatment facilities

4- Piping and Instrumentation Diagram (P&ID), cont.

P&ID for benzene distillation

5. Additional Diagrams

Utility flowsheetVessel sketchesStructural diagramsSupport diagramsPlot plansElevation diagrams

Isometric pictorial flow diagram

5. Additional DiagramsUtility Flow Diagram

Comparison

Note the details that were added through the development of flowsheet from BFD to P&ID(for the distillation tower for example) :1. Block Flow Diagram (BFD): The column was shown as a part of one of the three process blocks.2. Process Flow Diagram (PFD): The column was shown as the following set of individual equipment: a tower, condenser, reflux drum, reboiler, reflux pumps, and associated process controls.3. Piping and Instrumentation Diagram (P&ID): The column was shown as a comprehensive diagram that includes additional details such as pipe sizes, utility streams, sample taps, numerous indicators, and so on. It is the only unit operation on the diagram.

ReferencesE.E. Ludwig, Applied Process Design for Chemical and Petrochemical Plants, Third edition, Vol. 1, 1999.J.R. Couper, Chemical Process Design, 2nd edition, 2010.R. Turton,Analysis, Synthesis and Design of Chemical Process, 2002