Customer Story

Hybrid Heating Value Control for LNG Regasification

Maintaining 45 MJ/Nm3: How CHEMCAD Validated a Hybrid Heating Value Control System for LNG Terminal Operations  

Challenge Overview

In Japan, city gas supplied to distribution networks must consistently meet a strict standard heating value of 45 MJ/Nm3. At LNG terminals, this requires blending regasified LNG with LPG to adjust the heating value before pipeline injection. The challenge: multiple feed gas streams with varying flow rates and compositions, including nitrogen inert content, make conventional measurement and control methods unreliable. Sudden shifts in feed ratios can cause heating value deviations that violate supply standards.

Azbil developed a hybrid measurement system that combines a real-time thermal conductivity calorimeter with a gas chromatographic calorimeter that corrects for measurement bias caused by inert gases such as nitrogen, updating every five minutes. Before deploying this system in live plant operations, the control strategy required validation under dynamic feed conditions.

What You Will Learn

  • How CHEMCAD dynamic simulation based on material and energy balances was used to validate a novel hybrid heating value measurement and control system

  • How the simulation evaluated measurement accuracy, control stability, and optimal control parameters prior to Factory Acceptance Testing (FAT) and plant start-up

  • How the model confirmed stable heating value control of 45 MJ/Nm3 even under rapid changes in feed gas flow rates and composition

  • How a five-minute automatic bias correction cycle between two calorimeter instruments was modeled and validated in CHEMCAD

  • How pre-commissioning simulation reduced operational risk and shortened start-up time at the LNG terminal

Key Results

  • CHEMCAD simulation confirmed stable heating value control under dynamic feed conditions

  • Control behavior remained smooth around the 45 MJ/Nm3 target during composition and flow rate changes

  • Automatic bias correction between instruments performed reliably, as validated by simulation and confirmed in actual plant operation

  • Optimal control parameters were identified during FAT, reducing commissioning time and operational uncertainty at start-up

Case Study Snapshot

  • Product: CHEMCAD

  • Industry: Energy / LNG Regasification and City Gas Supply

  • Region: Japan

  • Application: Dynamic simulation, heating value control validation, LNG terminal commissioning

  • Key Methodology: Material and energy balance modeling, dynamic control simulation, hybrid calorimeter system validation