Process Flow Diagrams vs. Process and Instramentation Diagrams
courtesy of John Trumble, University of Michigan
This PFD/P&ID is taken from a brewery which is planned to produce 100,000 bottles a day of beer. This section includes boiling and fermentation. The process starts by using steam to boil the beer in KB-301, which sterilzes the beer. Next, the beer is pumped into a whirlpool filter where impurities are removed. The beer is then cooled to 15 degrees C, using a heat exchanger E-306. Once the beer is cooled, it is sent to the fermentation tank, TK-307. Here yeast is added, which metablozies sugar in the beer into alcohol and carbon dioxide. After a couple days, the beer is sent to a maturation tank, TK-314. The beer spends about 4 days in this tank, before it is clarified and bottled.
A PFD for the process is here:
The PFD contains stream compositions on the border, instead of the equipment. The overall flow rates through each stream can be seen on the PFD also.
A P&ID for the process is here:
The first difference to notice on the P&ID from a PFD is the border template. Instead of stream compositions being listed, there is a list of the equipment, along with a key for abbreviations used on the diagram. On the diagram itself, there are valves and controllers which are not present on a PFD. For example, V-5 is the valve right before the boiler or the pressure controller PC 1, which is represented by a circle located on the boiler. These devices are also not on the PFD.