Authors : Amarnath Thulasiraman

Volume/Issue : Volume 11 - 2026, Issue 9 - September

Google Scholar : https://tinyurl.com/35upyr3e

DOI : https://doi.org/10.38124/ijisrt/26sep701

Note : A published paper may take 4-5 working days from the publication date to appear in PlumX Metrics, Semantic Scholar, and ResearchGate.

Abstract : : Reciprocating gas engines used in wastewater treatment and biogas facilities are commonly integrated with Waste Heat Boilers (WHBs) for energy recovery. During engine start-up and shutdown operations, combustible gas accumulation within exhaust ducting systems can create a risk of internal explosions or deflagration events. Proper design and placement of explosion protection devices, particularly rupture discs, are therefore critical to maintaining duct integrity and personnel safety. This study presents a comprehensive steady-state and transient analysis of explosion protection systems installed in reciprocating engine exhaust ducting connected to a waste heat recovery system. Aspen HYSYS V14 was utilized to evaluate pressure distribution, temperature profiles, heat recovery performance, and transient pressure surge behavior under various operating scenarios involving biogas and natural gas firing. Three steady-state operating cases and three transient explosion scenarios were investigated. Dynamic simulations were conducted to validate rupture disc performance under deflagration conditions and to assess the effectiveness of single and dual rupture disc configurations. The results demonstrate that while normal operating back pressures remain well below the engine trip limit of 6 kPag, transient surge pressures can exceed design thresholds when only a single rupture disc is installed. The introduction of a secondary rupture disc at the WHB inlet significantly reduced peak surge pressures from approximately 50.7 kPag to less than 38 kPag. The study confirms that a dual rupture disc arrangement provides superior explosion protection and improves overall exhaust system safety.

Keywords : Aspen HYSYS, Waste Heat Boiler, Explosion Protection, Rupture Disc, Dynamic Simulation, Exhaust Ducting, Deflagration Analysis, Biogas Engine.

References :

1. AS 3814:2015, Industrial and Commercial Gas-Fired Appliances.
2. AS 1375, Industrial Fuel Fired Appliances.
3. API Standard 520, Sizing, Selection and Installation of Pressure Relieving Devices.
4. API Standard 521, Pressure Relieving and Depressuring Systems.
5. NFPA 68, Standard on Explosion Protection by Deflagration Venting.
6. ISO 4126, Safety Devices for Protection Against Excessive Pressure.
7. ISO 6184-4:2020, Explosion Protection Systems.
8. AspenTech, Aspen HYSYS V14 Process Simulation Software Documentation.
9. FM Global Data Sheet, Internal Combustion Engines.
10. FM Global Data Sheet, Gas Turbines.
11. NFPA 37:2021, Installation and Use of Stationary Combustion Engines and Gas Turbines.