cpgp day01-session 5 - drawing a process flow diagram 2012 final
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Drawing a Process Flow Diagram
What is a PFD
• A process flow diagram is a pictorial representation of what is happening in a process in a sequential order
• It is a snapshot of the process at the time of inspection
• It is a paper based tool
Why Draw a PFD
• Industries do not know
– What is wasted– Where is it generated
– How much is wasted
PFD for Cleaner Production
A simple diagram which uses only three main symbols and one auxiliary symbol
Not to be confused with other types of diagrams
Symbols to be Used
Rectangle is used for representing a process step
Arrow is used to show link and direction
Ellipse represents the beginning and the end of diagram
A Circle (with character or sign) is used to show continuation of a process
Tips in drawing a PFD
• List all the process steps prior to drawing PFD• Break larger steps into simpler steps as much as
possible• The PFD is drawn from top to bottom of a paper• Arrows link process steps in sequential order• Arrows linking process steps must always be
directed downwards (Top to Bottom PFD)• Labour, Time and Capital equipment not
included as inputs or waste streams• Inputs should be consumable items/material only
Always Start With an Ellipse
• Draw an ellipse on the top of the page and • Insert the name of the main raw material
which undergoes the change to form the final product within it
Raw Peanuts
Drawing Process Steps
• Process steps (activities) are depicted by rectangles
• Rectangles are drawn below the elipse, one per process step
• Sequential process steps (are linked by downward arrows
• Insert the name of the process step inside the rectangle
Storing
Raw Peanuts
De-shelling
Sorting
Frying
Indicating Resources Used
• Resources used are known as INPUTS
• Inputs are indicated on the left side of the rectangles (process steps)
• Inward arrows are drawn from each input material towards the rectangle
• Inputs are consumable material used to carry out the change to the main raw material at each process step
Electricity(Lighting)
LP GasCoconut Oil
Hot air
Storing
Raw Peanuts
De-shelling
Sorting
FryingElectricity(Lighting)
Electricity(Lighting)
Indicating Waste Streams
• Waste streams are known as OUTPUTS• Outputs are indicated on the right side of
the rectangle • Outward arrows are drawn towards each
Output stream from the rectangle• All waste stream generated at this point
should be indicated on the PFD
Shells Spilt nuts Dust
Oil SpillsNut spillsOil EvaporationWaste HeatExcess gasOver fried nuts
Storing
Raw Peanuts
De-shelling
Sorting
FryingLP Gas
Coconut Oil
Hot air
Electricity(Lighting)
Electricity(Lighting)
Electricity(Lighting)
Energy Loss
Foreign Matter Spilt nuts Dust
How to End the PFD
• The PFD is ended with an elipse depicting the finished product
Main Raw material
Finished product
Inputs Outputs
Shells Spilt nuts Dust
Oil SpillsNut spillsOil EvaporationWaste HeatExcess gasOver fried nuts
Storing
Raw Peanuts
De-shelling
Sorting
FryingLP GasCoconut Oil
Hot air
Electricity(Lighting)
Electricity(Lighting)
Electricity(Lighting)
Energy Loss
Foreign Matter Spilt nuts Dust
Oil DrainingOil Paper Drained Oil Used Oil Paper
Salting
Packing
Salt Spilt Salt Spilt nuts
Packing Material Rejected Packing MaterialSpilt NutsOverfilled packs
Fried Salted Peanuts
Continuation
• If one page is insufficient to complete the PFD, use another.
• Do not try to draw two PFDs on one paper.
• Arrows are never directed upwards
The following method is not correct
The following method though correct is not preferred
The following method is correct and preferred
Major Raw Material
A
Page 1
Finished Product
APage 2
Repeated Processes
Filtering
Mixing
Bagasse
Juice 1
Water
Electrical Energy
Sugar Cane
Crushing
Juice 2 Juice 3
Electrical Energy
FilteringBagasseElectrical
Energy
Mixing
Filtering BagasseElectrical Energy
Water
Electrical Energy
Branching
Preparing
Dyeing Printing Bleaching
Combining
Dyeing Printing Bleaching
Finishing
Auxiliary Processes
• Auxiliary processes are those that support the main process.
• They include cleaning, Bottle washing, Steam Generation, Water treatment etc.
• PFD for Auxiliary processes should be drawn separately and linked to the main PFD
Chemical SpillsWaste Chemicals
Cleaning
Chemical Washing
Hot water rinsing
First Washing
Bottles
Cleaned Bottles
B
Water
Electricity (Lighting)
Electricity (Lighting)
Electricity (Lighting)
Electricity (Lighting)
Chemicals
Hot Water
Energy Loss
Energy LossWater SpillsWaste Water
Energy Loss
Energy LossHot Water SpillsWaste Water
Boiling(Boiler)
FuelChemicals
Air
Flue Gas lossRadiation Heat lossSteam LeaksBlow-down loss
Water
Steam
A
Page 2
Mangoes
Washing
Peeling & Cutting
Crushing
Mixing
Page 1
Finished Product
Cooking
Cooling
Bottling
Labelling and Storing
Electricity (Lighting) WaterElectricity (Lighting)
Electricity
Electricity
SteamElectricitySugar
Electricity
BottlesElectricityCaps
ElectricityLabels
A
B
How to Indicate Cleaning Processes
• Pay attention to processes such as cleaning operations– Floor Cleaning– Machine Cleaning– Equipment Cleaning
• Such operations should also be indicated on the PFD
This Method is Wrong!
Mangoes
Washing
Peeling & Cutting
Crushing
Mixing
Bottled Mango Juice
Cooking
Cooling
Bottling
Labelling and Storing
Electricity (Lighting) WaterElectricity (Lighting)
Electricity
Electricity
SteamElectricitySugar
Electricity
BottlesElectricityCaps
ElectricityLabels
A
B
WaterDetergents
How to Indicate Cleaning of the Juice Cooking Pan Page 1
Mangoes
Washing
Peeling & Cutting
Crushing
Mixing
Bottled Mango Juice
Cooking
Cooling
Bottling
Labelling and Storing
Electricity (Lighting) WaterElectricity (Lighting)
Electricity
Electricity
SteamElectricitySugar
Electricity
BottlesElectricityCaps
ElectricityLabels
A
B
C
Page 2
Washing
Electricity (Lighting)
C Pan Cleaning Process
Detergents
Hot Water
Energy Loss
Waste Water
Water Spills
Detergent Spills
PFDs for Services
• The PFD for a service organization may be drawn as a block diagram/Unit Process
• These are prepared for activities that do not have sequential steps, such as Boilers, Housekeeping activities in Hotels, Kitchen activities in Hotels etc.
House keeping
Room
Cleaned Room
Energy
Room cleaning chemicals
Cotton Rags
Toilet cleaning chemicals
Tissue Paper
Toilet paper rolls
Use of Use of Raw MaterialsRaw Materials ManufactureManufacture DistributionDistribution UseUse DisposalDisposal
Product Life CycleProduct Life Cycle
For PFDs are not drawn for products We can draw Life Cycle Diagrams
Can we Draw PFDs for Products?
Wording
• All process steps are considered to be dynamic (process step is taking place at the time of observation)
• Therefore all steps are referred in present continuous – Checking
FryingDyeingDrying
• Do not Mention the equipment as the process step
• These terms are wrong- Dry - Dye - Fry- Dried - Dyed - Fried- Dryer - Dying Machine - Frying Pan
Additional points
• However small the resource quantity may be indicate it on the PFD.
• However small the waste stream may be indicate it on the PFD.
• When considering the process steps the normal, abnormal, occasional ,accidental and maintenance operations should also be taken into account
Other Tools
Ecomapping - One little picture says more than a long speech !
• A visual, simple and practical tool to analyse and manage the environmental performance of companies industries
• An easy, creative and systematic method of obtaining environmental data
• An awareness - creation and learning tool based on the physical reality of the company
• A dynamic inventory of the changes in the environmental behaviour of the company
How to Use Eco-maps• Indispensable materials
– A4 -sized paper and a photocopy machine.• Time needed
– Less than one hour of work for each map.• When to do it?
– After the end of the accounting year.• How often should they be up-dated ?
– Once a year, or if the site is renovated, or activities are extended.
• Filing– With documentation for your environmental
management system, with your annual accounts .• Who can use them?
– The maps can be used by many different types of companies: from small manufacturing and service companies to large structures and local authorities.
How to Eco-map
1. Prepare Map of the urban situation
• Make a map of the site, seen from above, including car parks, access areas, roads and the surrounding environment.
• It should show the real situation.
2. Map of the site• Draw the outline of the site using
a scale and showing the interior spaces. This map should be copied and will be the basis for the work to be done.
• The maps should show the real situation - they should be simple, recognisable and in proportion. Maps should have a date, a name and a reference. Integrate one or two significant objects such as machines and boilers, which will enable the user to orient himself with the site easily
• If the site covers very different areas, individual maps of the different areas can be prepared and brought together.
3. Symbols• Develop your own
symbols, but use at least two Hatched lines: small problem (area to be monitored, problem to be studied)
• Circle: large problem (stop, corrective action)
• The more serious the problem, the thicker the circle
Case Study
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