Flue Gas & Emissions

To produce heat, systems like furnaces, boilers, and heaters burn fuel in the presence of oxygen. The system must have a good input balance of fuel and air to achieve efficient combustion, thus maximizing energy output while keeping costs down. Efficient combustion reduces the amount of pollutants such as nitrogen dioxide (NO2), nitric oxide (NO), sulfur dioxide (SO2), and particulate matter released into the air.

A good way to optimize fuel and air input into these systems involves measuring the exhaust gas. A flue gas and emissions analyzer measures the concentration of gases and can be used by the operator to make intelligent adjustments to the burners on a boiler to reach optimal combustion. It may also be useful for measuring pollutants in the exhaust for environmental reporting purposes.

What Are Flue Gas & Emissions?

A flue is a long pipe that functions as a chimney or duct that discharges exhaust gases. These flue gases are the byproducts of combustion and may have a wide range of compositions based on fuel type(s) and the type of combustion equipment/process being measured. Emissions refer to the gases and particulate matter that are released into the atmosphere as a result of burning fuels. Excess emissions into the environment lead to poor air quality and harmful pollution, and may also be an indicator of improper or inefficient combustion.

CEM Systems

CEMS is an acronym for Continuous Emissions Monitoring System. This term can technically apply to any instrument that is measuring some of the various constituents of exhaust gas on a continuous basis. However, the generally accepted use of “CEMS” refers to an analyzer system that conforms to the methodologies and design features as outlined by a government environmental department such as the Environmental Protection Agency in the USA. Acceptable methods for sample conditioning, gas measurement, reporting of results, and other functions are established by the governing body and the resulting data will be accepted in emissions reports made to the government by the user.

In many countries, industrial facilities are required to report their emissions of various exhaust gases that are considered “criteria pollutants.” CEMS equipment can provide continuous analysis of many of these gases and can be used to report emissions. Particulate matter measurements may also be grouped with CEMS requirements. While not a gas itself, particulate matter does have environmental and health effects when it is small enough to be suspended in the atmosphere.

CEMS equipment usually tends to be quite expensive and may be an unsustainable cost for a facility. To satisfy the reporting requirements while minimizing equipment costs, some facilities install a lower-cost non-compliant analysis system at their emissions point. The analysis system is non-compliant in the sense that alternate conditioning and measurement methodologies not accepted by the governing agency are used in the gas analyzer. Once a year, the facility obtains the services of a mobile CEMS company to measure emissions using compliant equipment. The results are compared, and the relative accuracy of the installed non-compliant analyzer system is determined.

Applications of Flue Gas & Emissions Analyzers

Flue gas and emissions analyzers play an important role in determining the amount and type of emissions exiting the combustion process. Potential combustion applications include:

• Furnaces
• Biomass or methane/natural gas boilers
• Heaters
• Engine exhaust
• Biogas CHP cogeneration
• Diesel generator sets
• others

Analyzers can detect pollutants and gases such as O2, CO, CO2, SO2, NO, and NO2. They allow the operator to make informed adjustments to the process in order to achieve the best efficiency.

How Does a Flue Gas & Emissions Analyzer Work?

To analyze flue gas and emissions, a probe is inserted into the flue of a furnace or boiler between the last heat exchanger and the draft diverter. The gas analyzer will use a pump to pull a sample out of the flue. Depending on the gas being analyzed, the internal sensors will usually be either electrochemical or infrared types. Additional values may be calculated based on which gases are measured. Gas readings on the analyzer will display as parts per million (ppm) or as a percentage, depending on the gas characteristics.

How Do You Choose a Flue Gas & Emissions Analyzer?

Flue gas and emissions analyzers are used in commercial, industrial, and even residential facilities. The type of analyzer required will depend on:

• The gases/emissions to be monitored
• Whether the main need is for efficiency, environmental regulation/compliance, or both
• The level of accuracy required
• Whether the analysis will be spot-checked on a periodic basis or continuously monitored

When choosing a flue gas and emissions analyzer, it is important to match the product to its use. Residential analyzers may require a lower CO detection threshold than commercial or industrial sensors. The sampling probe should be robust enough to handle the application’s requirements. In addition to functionality, consider the service and maintenance costs that will be required.

Nova Capabilities

Nova has capability in the non-compliant CEMS category. Nova systems are accurate and durable, but they use some methodologies which may not be approved by some governmental agencies. These systems will require a Relative Accuracy Test Audit (RATA) once a year to evaluate the reporting accuracy of the combustion gas analyzer.

The Nova 7200 Flue Gas Analyzer System uses the following measurement technologies:

• Oxygen by electrochemical sensor, range 0-25.0%
• Carbon monoxide by electrochemical sensor, range 0-1,000 PPM
• Carbon monoxide by infrared detector, range 0-2,000 PPM to 0-10.0%
• Carbon dioxide by infrared detector, range 0-20.0%
• Nitric oxide by electrochemical sensor, range 0-2,000 PPM
• Nitrogen dioxide by electrochemical sensor, range 0-800 PPM
• Nitrogen dioxide calculation, based on nitric oxide measurement
• Sulfur dioxide by infrared detector, range 0-2,000 PPM
• Stack temperature by Type K thermocouple, range 32 °F – 1800 °F or 0 °C – 1000 °C

Combinations of the above gas measurement options are usually also purchased with oxygen measurement. This allows the user to “normalize” the other gas readings to oxygen. That is, they allow the other gas readings to be corrected by the customer to a reference oxygen content.

Our continuous flue gas analyzers are sturdy and weatherproof. They are able to function in temperatures from -22 °F to over 100 °F with the appropriate weather package options. They can also be modified with extra filtration devices for improved sample quality.

Nova analyzers use reliable high-volume pumps for quick analysis times. In our stack gas analyzers, the detectors and sensors can reach 90% of reading in less than 20-30 seconds in most cases. (Sample line lengths will add to response time.)

Here are links to the online catalog:

• 7200 Continuous Flue Gas Analyzer System for Clean Gas
• 7240 Heated Probe & Filter System

Other features of the Nova Flue Gas Analyzer Systems:

• A variety of available cabinet packages allow for easy installation in different climates.
• Our continuous exhaust analyzers can be customized to include multiple sample extraction points.
• Hazardous area purge kits are available by request.
• Most continuous flue gas analyzers can be supplied with an optional Serial Output Package with a USB, RS-232, Ethernet, or RS-485 connection.

Portable Flue Gas Analyzer Models

Nova has produced portable flue gas analyzers for more than 35 years. Technicians and facilities choose Nova systems because they’re versatile, intuitive, easy to use, and durable.

Flue gas analysis using a Nova flue gas analyzer will enable you to measure the concentrations of pollutants present and adjust burners on a boiler for optimal combustion. Nova exhaust gas analyzers are useful for environmental control, general boiler maintenance, and reducing fuel costs.

Here are links to Nova’s portable flue gas analyzers:

• 5300FG Series Portable Flue Gas Analyzers
• Portable thermo-electric style pre-cooler
• Portable ice-bath style pre-cooler

Flue Gas & Emissions Analyzers From Nova Analytical Systems

Nova Analytical Systems manufactures continuous and portable flue gas & emissions analyzers. Nova also offers gas analyzers for other applications, using three main types of sensors/detectors: non-dispersive infrared (NDIR), electrochemical, and thermal conductivity. Our product offerings include:

• Continuous Gas Analyzers
• Portable Gas Analyzers
• Flue Gas Analyzers
• Hazardous Area Analyzers
• Heat-Treating and Metal Finishing Analyzers
• Landfill Gas Analyzers
• Dew Point Analyzers
• Oil & Gas Industry Analyzers
• Portable Engine Exhaust Analyzers
• Power Generation and Hydrogen Purity Analyzers
• Process Gas Analyzers
• Steel-Making Analyzers
• Syngas Analyzers
• Other Energy Intensive and Remote Location Analyzers

With more than 40 years of experience in the industry, Nova Analytical Systems has the equipment and expertise to build reliable emissions analyzers for many types of combustion processes. Contact us or request a quote to get started on your solution.