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Wobbe Index, BTU & Heating Value Calorimeters

Wobbe Index, BTU & Heating Value Calorimeters

Changing fuel gas composition can affect burner performance, energy input, air-to-fuel ratio, emissions, and process efficiency.

COSA XENTAUR™ industrial calorimeters from Process Insights provide continuous, real-time measurement of critical fuel gas properties including:  Wobbe Index | Heating Value (BTU) | Calorific Value | CARI | Specific Gravity

Designed for fuel gas, flare gas, natural gas, refinery gas, hydrogen blends, biogas, RNG, syngas, and other combustible gases, our calorimeters give operators the real-time information needed to improve combustion control, optimize fuel use, and respond quickly to changing gas composition. Process Insights’ existing portfolio supports both continuous measurement and injection-style calorimetry.

Talk to a Calorimeter Application Expert

Why Measure Both Wobbe Index and CARI?

Energy Control and Air/Fuel Control Are Not the Same Thing.

  • Wobbe Index provides information about the energy delivered through a fuel system and the interchangeability of different fuel gases.
  • CARI (Combustion Air Requirement Index) provides information about the amount of combustion air required by the fuel.

We offer two types of calorimeters.

9800 CXi Injection-Style Calorimeter

Zero-Hydrocarbon-Emissions BTU & Flare Gas Analysis

The COSA XENTAUR 9800 CXi is an injection-style calorimeter designed for demanding fuel gas and flare gas applications.  Unlike traditional continuous flame calorimeters, the 9800 CXi injects a precisely controlled sample into a combustion air stream inside a 1000°C flameless furnace.  Most sample gas is returned to the process through the fast loop, while only a small injected portion is consumed during analysis.

Key Advantages

  • Zero Hydrocarbon Emissions – Designed to avoid continuous hydrocarbon emissions associated with traditional flame calorimeters.
  • High-Temperature Combustion – The 1000°C furnace promotes complete oxidation.
  • High-Sulfur Gas Capability – Designed to reduce sulfur-related fouling problems encountered by some conventional calorimeters.
  • No Flameouts – Flameless operation eliminates flame stability concerns.
  • Direct Heating Value Measurement – Measure BTU without requiring a specific gravity measurement for the base heating-value determination.
  • Small Footprint – Designed for industrial installation where analyzer space matters.

9610 CXc Continuous Calorimeter

Fast Wobbe Index, Heating Value & CARI Measurement

The COSA XENTAUR 9610 CXc provides continuous measurement of Wobbe Index, Heating Value, Calorific Value and CARI for changing fuel gas streams.  Its measurement principle uses controlled catalytic combustion followed by measurement of residual oxygen with a zirconia sensor.  This provides a fast, stable measurement without relying on a continuously maintained flame.

Key Advantages

  • T90 <5 Seconds – Fast response supports real-time combustion control in the base analyzer configuration.
  • Direct CARI Measurement – Provides combustion-air information for air/fuel ratio control.
  • Wobbe Index Measurement – Supports energy-flow and fuel-interchangeability control.
  • Low-BTU Gas Capability – Designed to handle a broad range of combustible gases.
  • No Flameouts – Catalytic oxidation avoids traditional flame stability concerns.
  • Hazardous-Area Options – Designed for demanding industrial installations.
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Why Choose COSA XENTAUR?

Built for Real-Time Combustion Measurement

Process Insights’ COSA XENTAUR calorimeters are engineered and manufactured in Houston, Texas, and the brand’s calorimeter technology is designed for demanding fuel gas, flare gas, combustion-control, and gas-quality applications.

  • Fast Response – Real-time measurements for active combustion control.
  • Direct CARI Measurement – Better visibility into changing combustion-air requirements.
  • Flameless Measurement – Avoid traditional flameout concerns.
  • Difficult Gas Capability – Solutions for low-BTU, high-sulfur, hydrogen-containing, and changing fuel streams.
  • Two Measurement Technologies – Choose continuous or injection-style calorimetry based on the application.
  • Application Engineering – Match analyzer technology and configuration to the actual gas composition and control objective.

Two Calorimeter Technologies. One Goal.

Which COSA XENTAUR Calorimeter Is Right for Your Application?

9800 CXi™ 9610 CXc™
Technology Injection-style high-temperature combustion Continuous residual-O₂ measurement
Primary Strength Zero-hydrocarbon-emissions measurement Fast continuous combustion control
Heating Value / BTU ✓ ✓
Wobbe Index Available/configuration dependent ✓
CARI Available/configuration dependent ✓
Specific Gravity Optional depending on measurement configuration Available
Flare Gas Excellent fit ✓
Fuel Gas ✓ Excellent fit
High-Sulfur Gas Excellent fit Application dependent
Hydrogen Blends ✓ ✓
Natural Gas ✓ ✓
RNG / Biogas ✓ ✓
Combustion Control ✓ Excellent fit

What Do Our Calorimeters Measure?

Measurement What It Tells You Why It Matters
Wobbe Index Interchangeability and combustion energy of fuel gases Helps maintain consistent energy input when gas composition changes
Heating Value / BTU Amount of energy available from the fuel Supports fuel quality, energy control and process optimization
Calorific Value Heat released during complete combustion Helps determine the energy content of the gas
CARI Combustion air requirement relative to gas density Supports precise air-to-fuel ratio control
Specific Gravity Gas density relative to air Used for gas characterization and calculation of combustion properties
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Wobbe Index, BTU & Heating Value Calorimeters

9800 CXi™ Injection-Style Calorimeter

COSA XENTAUR™ Zero-Hydrocarbon-Emissions for BTU Fuel Gas & Flare Gas Analysis
NEW - 9800 CXi Calorimeter v23

9610 CXc™ Continuous Calorimeter

COSA XENTAUR™ Wobbe Index, Heating Value, Calorific Value and CARI Measurements
Process Insights 9610 CXC calorimeter

Industries

  • Natural Gas: Used in the natural gas industry to measure the heating value of natural gas for billing and quality control purposes.
  • Refineries: Used in refineries to measure the calorific value of fuels and feedstocks for process control and optimization.
  • Power Generation: Used in the power generation industry to measure the heating value of hydrocarbon fuels and Hydrogen used in boilers and turbines. and other fuels.
  • Biogas: Used in the biogas industry to measure the heating value of biogas produced from organic waste.
  • Chemicals: Used in the chemicals industry to measure the calorific value of fuels and feedstocks used in chemical processes.
  • Oil and Gas: Used in the oil and gas industry for measuring the heating value of natural gas, propane, butane, and other fuels.
  • Petrochemical: Used for measuring the calorific value of different hydrocarbon feedstocks such as Methane, Ethane, Ethylene, etc.
  • Environmental: Used in the Refinery, Chemical and Midstream industry to monitor flares.
  • Co-Generation: Used to measure the heating value of high value waste hydrocarbon gases for the use in boilers and turbines.

    Applications

    • Natural Gas Blending – Use Wobbe Index and Heating Value measurements to control gas blending and maintain target fuel quality.
    • Fuel Gas Optimization – Continuously monitor changing fuel quality to improve burner, furnace, heater, and boiler control.
    • Flare Gas Monitoring – Measure heating value and other combustion properties of flare gas for flare management, process control, and applicable environmental monitoring programs.
    • Refinery Fuel Gas – Monitor changing refinery fuel networks containing varying concentrations of hydrogen, methane, light hydrocarbons, and other gases.
    • Hydrogen Blending – Measure changing combustion properties as hydrogen is blended into natural gas or other fuel streams.
    • Natural Gas Blending – Use Wobbe Index and Heating Value measurements to control gas blending and maintain target fuel quality.
    • Renewable Natural Gas & Biogas – Monitor variable gas quality from landfill gas, digesters, RNG upgrading, and pipeline injection applications.
    • Gas Turbines – Maintain more consistent energy input as fuel composition changes.
    • Boilers & Furnaces – Use real-time fuel information to improve combustion control and process efficiency.
    • Syngas & Low-BTU Gas – Measure changing combustion properties in lower-calorific-value gases used for industrial energy recovery.

    Key Customer Challenges

    1. Changing Fuel Gas Composition

    Customer Challenge

    “What happens to our combustion process when the fuel changes?”

    Refinery fuel gas, flare gas, biogas, RNG, hydrogen blends, and other process fuels can vary significantly in composition.

    Process Insights Solution

    Continuous measurement of Wobbe Index, Heating Value and CARI provides real-time information operators can use to adjust combustion as fuel quality changes.

    2. Controlling the Air/Fuel Ratio

    Customer Challenge

    “Are we giving the burner the right amount of air for the fuel we’re actually burning?”

    Fuel composition changes can change combustion air requirements.

    Process Insights Solution

    Direct CARI measurement provides information specifically related to the combustion air requirement of the gas, supporting tighter air/fuel ratio control.

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    3. Measuring Difficult Flare Gas

    Customer Challenge

    “Can our calorimeter handle a changing, sulfur-rich flare stream without becoming a maintenance problem?”

    Sulfur-rich streams can create maintenance problems for some calorimeter designs.

    Process Insights Solution

    The 9800 CXi’s 1000°C combustion furnace is designed to completely oxidize sulfur compounds, helping minimize sulfur buildup and support reliable flare gas measurement.

    4. Getting the Measurement Fast Enough

    Customer Challenge

    “Are we measuring the fuel fast enough to actually control combustion?”

    A measurement arriving after the fuel composition has changed has limited value for feed-forward control.

    Process Insights Solution

    The 9610 CXc provides T90 response under five seconds in its base configuration, giving control systems fast information about changing fuel properties.

    Frequently Asked Questions

    What is a Wobbe Index analyzer?

    A Wobbe Index analyzer continuously measures a fuel-gas property used to compare the combustion energy output of different fuel gases. Wobbe Index is particularly useful for monitoring changing fuel composition, gas blending, combustion control, and turbine applications.

    What is a BTU analyzer?

    A BTU analyzer measures the heating or calorific value of a gas, indicating how much energy the gas can release during combustion.

    What is the difference between Wobbe Index and Heating Value?

    Heating Value describes the energy contained in a fuel. Wobbe Index relates heating value to the gas’s specific gravity and is used to compare the combustion behavior of different fuel gases.

    What is CARI?

    CARI stands for Combustion Air Requirement Index. It represents the combustion-air requirement of a fuel relative to its specific gravity and can be used to support air/fuel ratio control.

    Why measure both Wobbe Index and CARI?

    Wobbe Index and CARI provide different information. Wobbe Index is useful for controlling energy input, while CARI relates to combustion-air requirement. This distinction becomes especially important for fuels containing components such as hydrogen or carbon monoxide.

    What gases can a COSA XENTAUR calorimeter measure?

    Process Insights calorimeters are used with fuel gas, flare gas, natural gas, refinery gas, biogas, renewable natural gas, hydrogen blends, syngas, and other combustible gases.

    Which calorimeter is best for flare gas?

    For demanding flare gas applications, particularly sulfur-containing streams or applications where minimizing hydrocarbon emissions is important, the 9800 CXi injection-style calorimeter is designed specifically around these challenges.

    Which calorimeter is best for combustion control?

    The 9610 CXc is designed for continuous Wobbe Index, Heating Value and CARI measurement and has a documented T90 response of less than five seconds in its base configuration, making it well suited to fast combustion-control applications.

    Can calorimeters measure hydrogen-containing fuel gases?

    Yes. Process Insights positions its calorimeters for hydrogen and hydrogen-blend applications. The exact measurement configuration should be selected based on gas composition, concentration range, and required outputs.