Pressure Relief Sizing of Reactive Systems
Reactive systems present a unique challenge for pressure relief sizing because the source of pressure is not just vapor expansion — it is chemical energy. In reactive systems, the relief device must be sized to safely discharge the worst-case pressure rise that can occur due to runaway reactions, decomposition, polymerization, or other exothermic conditions.
At Belmont Scientific, we apply data-driven reactivity characterization to design properly sized relief systems for chemical reaction hazards.
Specialized relief sizing where the source term can grow due to chemical reaction:
Reaction-driven scenario development (e.g., runaway, self-accelerating decomposition)
Lab-supported heat and gas generation rates
Determination of required relief area and set points based on worst-case adiabatic/dynamic scenarios
Integration of kinetic modeling outputs to capture realistic heat/gas evolution
Why Choose Belmont Scientific?
References
Article: “Pressure relief sizing of reactive system using DIERS simplified methods and dynamic simulation method”
Authors: Surendra K. Singh, Richard Huh
Read here: https://doi.org/10.1016/j.jlp.2016.08.017
Frequently Asked Questions (FAQ)
1. What are the industry standards or guidelines for reactive relief system design?
- DIERS Guidelines (AIChE) – foundational framework for reactive vent sizing
- API 520 / 521 – Relief system design and venting of reactive systems
- CCPS Guidelines for Safe Handling of Reactive Chemicals – kinetic data and modeling practices
2. Why are reactive PSVs more complex to size than non-reactive ones?
Reactive systems can generate heat and gaseous products that accelerate over time (runaway reactions). Sizing must account for the worst credible rate of gas production and heat release — often requiring laboratory calorimetry and kinetic modeling to quantify the source term.
3. How do we support reactive PSV design?
We integrate experimental calorimetry with advanced modeling to determine actual relief loads. This includes:
- DSC – exotherm onset temperature & heat release
- ARC / APTAC / VSP2 – adiabatic rate data, self-heat rate, gas generation
- Kinetic modeling using calorimetry data
- Two-phase relief analysis where gas + liquid disengagement is likely
Outputs from these test programs feed directly into DIERS-based vent sizing calculations.
4. What are the typical reactive scenarios we evaluate?
- Thermal runaway of batch reactions
- Accumulation of unreacted peroxide or energetic intermediates
- Polymerization / auto-acceleration
- Exothermic decomposition
- Incorrect charging order
- Cooling failure
5. Is it possible that the required vent size is extremely large?
Yes. Some runaways generate enormous gas generation rates. This is why proper reactivity testing is critical early in process development.
6. Can DIERS two-phase methodology be applied to reactive systems?
Yes. Two-phase venting often becomes the controlling scenario for reactive mixtures.