Project Synopsis

Refinery pressure relief valve evaluation for determining relief valve capacities at current process throughput rates.

Project Summary


Process Engineering Associates, LLC (PROCESS) was contracted by the client to conduct a comprehensive evaluation of their refinery pressure relief valves for the purpose of determining relief valve capacities relative to current process throughput rates.  Project elements included:

  • Refinery process information review
  • Heat and mass balance and vapor-liquid equilibrium calculations preparation
  • Relief valve relief requirements and capacities evaluation
  • Relief mitigation process engineering alternatives evaluation.

PROCESS reviewed the client’s engineering documentation to identify existing relief valve locations, applications, and sizes.  Existing heat and mass balance information was also reviewed and additional heat and mass balance and vapor-liquid equilibrium calculations were performed by PROCESS to complete the refinery throughput information required for the relief valve evaluation.  PROCESS then used proprietary in-house computer programming technology to evaluate the vapor and liquid relief capacities of each relief valve as well as relief requirements for identified potential pressure relief scenarios, including:

  • Blocked liquid and/or vapor flow
  • External fire
  • Loss of cooling
  • Loss of power
  • Gas blowby
  • Malfunctioning control valve
  • Heat exchanger tube failure
  • Reverse/misdirected flow
  • All other pressure relief scenarios identified during the course of the evaluation.

The same computer technology was used to calculate the required size for relief valves determined to be under-sized for the current applications.  Finally, PROCESS executed alternatives evaluations for undersized valves to determine if modifications to the process could be made in order to mitigate the undersized relief protection without replacing the existing valves.

Relief valve evaluations were performed for 267 valves for the following refinery process units:

  • Crude
  • Propylene fractionation
  • Hydrodesulfurization
  • Reformer
  • Fluidized catalytic cracking
  • Fluidized catalytic cracking light ends recovery
  • Light distillate, gas oil, and diesel hydrotreaters
  • Fuel gas treater
  • Vacuum
  • Propane deasphalting
  • Aromex
  • Reformate splitter
  • Saturate light ends recovery
  • Sulfur recovery
  • SCOT tail gas
  • Sour water stripper
  • Propylene recovery
  • Tank farm.

Industry Type

  • Petroleum Refining

Utilized Skills

  • VLE calculations
  • Heat and mass balance
  • Computer process simulation
  • Pressure relief valve (PRV) and pressure safety valve (PSV) sizing
  • Comprehensive relief valve evaluation

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