Session: 04-11-01 Posters

Paper Number: 191583

191583 - Feasibility Assessment of Fuel Switching from By-Product Gases to LNG in an Industrial Combined-Cycle Power System 

Abstract: 

An integrated steelworks is expected to face a growing by-product gas supply imbalance due to the planned closure of certain upstream process units, resulting in reduced availability of fuel oil gas (FOG) and coke oven gas (COG). Since FOG currently accounts for a large share of the thermal input to the site’s by-product gas combined-cycle power system, a transition to liquefied natural gas (LNG) is becoming increasingly important. This transition is required not only to maintain stable plant operation under changing fuel supply conditions, but also to support net-zero and decarbonization goals by replacing carbon-intensive by-product fuels with a cleaner alternative.

Fuel switching in such systems involves two major technical challenges: gas compressor operability and combustor compatibility. Changes in fuel composition affect gas density, molecular weight, and required flow rate, which can shift the compressor operating point and increase the risk of surge and vibration during transient conditions. At the same time, changes in calorific value, Wobbe index, flame speed, and dilution gas fraction may alter the flame stability regime, leading to combustion instability, blow-off, flashback, and emissions variation.

This study evaluates the feasibility of by-product gas-to-LNG switching in an industrial combined-cycle power system. For the COG-to-LNG case, no significant issues were identified in either compressor surge margin or combustor compatibility. For the FOG-to-LNG case, feasibility was confirmed up to a 30% LNG substitution ratio under normal operating conditions, while additional fuel control was found to be necessary under infrequent extreme conditions.

The results indicate that LNG can serve as an effective transition fuel for both operational flexibility and carbon reduction, providing practical support for phased fuel conversion in industrial power systems under future net-zero scenarios.

Presenting Author: Soohwan Jeon Research Institute of Industrial Science & Technology

Presenting Author Biography: Soohwan Jeon received his B.S. in Mechanical Engineering from Inha University and his M.S./ Ph.D. in Pohang University of Science
and Technology (POSTECH). He is a researcher of at Research Institute of Industrial Science & Technology (RIST).

Authors:

Soohwan Jeon Research Institute of Industrial Science & Technology
Hyunsu Kang Research Institute of Industrial Science & Technology
Taeyoung Kim Research Institute of Industrial Science & Technology
Hyeon gu Kang POhang Iron & Steel COmpany (POSCO)
Young Hoon Choi POhang Iron & Steel COmpany (POSCO)
Woo Chan Kim POhang Iron & Steel COmpany (POSCO)
Suk Hwan Park POhang Iron & Steel COmpany(POSCO)