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// Process Topology

  • The location of and interaction between equipment and process streams is referred as the process topology.
  • The topology of the process – showing the connectivity of all the streams and the equipment
Chemical Engineering Design: Principles, Practice and Economics of Plant and Process Design

// 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
  • 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
  • Consider the unit operation P-101A/B

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

// Example 1

Operators report frequent problems with E-102, which are to be investigated. The PFD for the plant’s 100 area is reviewed, and E-102 is identified as the “Reactor Effluent Cooler.” The process stream entering the cooler is a mixture of condensable and noncondensable gases at 654 ˚C that are partially condensed to form a two-phase mixture. The coolant is water at 30 ˚C. These conditions characterize a complex heat transfer problem. In addition, operators have noticed that the pressure drop across E-102 fluctuates wildly at certain times, making control of the process difficult Because of the frequent problems with this exchanger, it is recommended that E-102 be replaced by two separate heat exchangers. The first exchanger cools the effluent gas and generates steam needed in the plant. The second exchanger uses cooling water to reach the desired exit temperature of 38°C. These exchangers are to be designated as E-107 (reactor effluent boiler) and E-108 (reactor effluent condenser).

Why E-102 cannot be reassigned to the new equipment?