Other Challenging Applications & Ideas

On this page, we have posted information about gas analyzers that may or may not be shown in our catalog. These analyzers have been developed in response to special applications or projects that we have worked on.

Your application may have some similarity to one of the items shown below. Or your application may have no similarity to anything shown on our website or catalog at all. In either case, you are welcome to contact us with your inquiry.

Some applications require that the analyzer be installed outdoors or in remote locations. This may expose the analyzer equipment to harsh temperatures or corrosive environments.

Other energy intensive applications may produce high heat, high pressure, moisture, dust, and other by-products that may pose a challenge to analyzer functionality.

Rotary kilns

Are used to dry or prepare various kinds of loose materials. Gas analysis may be required to determine condition of burner, fuel ratio, emissions, or other parameters related to the combustion.
High Dust requires Nova Model 7240 Probe & Heated Filter System to be installed at sample extraction point.
Gas sample is pulled to Nova 860 Series Industrial Flue Gas Analyzers.
Gas analysis typically consists of measuring O₂ / CO / CO₂ at percent (%) levels. Sometimes NO / NO₂ / SO₂ measured in parts-per-million (ppm) levels are also required.

Production Baking Oven Monitoring (food industry)

Many mass-produced baked goods, such as breads and buns, are prepared using highly automated production lines. The preparation process usually culminates in tunnel-type baking ovens that can be 15m (50ft) or more in length.

The ovens are often fired using a series of natural gas burners located throughout the hot sections of the tunnel. As with steel heat-treating furnaces, having a well-balanced flame at each burner will ensure proper temperature achievement, even heat distribution, fuel efficiency, and prevention of fuel waste. The occurrence of deficient start-ups and flame-outs can result in un-burned fuel accumulating in the oven atmosphere. This can create a dangerous situation if the LEL (lower explosive limit) of the fuel is achieved anywhere in the various sections of the oven tunnel.

To monitor LEL in tunnel ovens, a series of in-situ catalytic style sensors is sometimes used. The on-going functionality and maintenance of these sensors can sometimes be a challenge in this environment.

One alternative approach is to use one continuous analyzer that extracts a sample from somewhere at or near the oven vent. The analyzer is usually installed near the oven control system, close to the oven itself. The analyzer’s built-in pump pulls a sample from the oven vent and runs it through a cooler to condense out as much water as possible. Measurement of methane (CH₄) is continuously done using an infrared detector. The readings are reported on a visual numeric display at the analyzer, and over a 4-20mA signal. Various relay contacts can be used to report alarm conditions.

Challenges include:

Water accumulation – the fuel combustion together with off-gas from the baked goods results in a very moist atmosphere. The water condenses in the tubing and later on in the analyzer. Accumulation of water can impede flow and disrupt the functionality of the detector and electronics. A cooler with drain pump will help capture excess moisture and separate it from the sample gas.
Contamination – the biological character of baked goods combined with the abundance of moisture can result in fouling of the components in the analyzer sample path. As foulants accumulate, they can load up the filters, impede solenoid valves, and eventually block flow. Installing a heated pre-filter at the sample extraction point is a good step in removing any solids. Thoroughly drying the sample helps stifle fouling growth in the sample path. A sample cooler seems to be the best solution for this.
Quality of Installation – it is best practice to extract the sample using a stand-pipe arrangement to which the heated filter is attached. Immediate condensate will drip down the stand pipe and back into the oven. Particulate / soot is trapped at the heated filter while post-stand-pipe condensation is allowed to travel onward. The tubing that carries the sample gas to the analyzer should be installed without dips or valleys that result in pooling of water in the tubing. Where possible, the tubing should slope down toward the analyzer for disposal at the cooler. Poor installation of system can compromise good analyzer design.
Reliability of detection – the traditional catalytic detectors usually function acceptably if under favorable conditions. However, the moist sample gas, oven vibration, and heat can sometimes affect the functionality of the sensors and reliability of the readings. Nova’s preferred solution is to use an infrared detector to measure CH₄ in the vent gas. Infrared detectors are not slowly consumed during the detection process, can be more easily protected from sample moisture, and can continue to function even when there is no oxygen (O₂) in the sample gas.
Facility Environment and Maintenance – Baking facility tend to be hot environments, especially near the ovens. High ambient temperature can compromise the analyzer electronics and efficiency of the sample cooler. It is therefore good to have cabinet temperature management built into the analyzer. Analyzers that monitor CH₄ LEL in baking oven atmospheres are considered a safety feature, and are not directly associated with production. Thus, they tend not to receive proper maintenance attention. Analyzer systems with easy / automatic calibration are appreciated in this case. Maintenance alerts that advise the operators of recommended filter change-outs or other tasks are also a good idea.
Facility Safety and Production Priorities – Since LEL monitors are a safety feature, they may be interlocked with the oven burner system. If an alarm condition occurs, the oven may be automatically shut down, thus affecting production. If an alarm condition is bypassed, the oven will be un-monitored and thus operating in a potentially dangerous manner. Thus, it is imperative that the LEL analyzer receive regular maintenance attention ensure that it is operating properly and providing reliable LEL data.

Nova Model 870 Series Continuous CH₄ Detector can be configured to successfully meet the above challenges while delivering a reliable CH₄ reading. It uses a non-consuming infrared detector calibrated for methane-specific analysis which allows better visibility of CH₄ in a background of mixed baking oven gases. The Nova ‘Smart Control’ function allow easier calibration, diagnostics, & alarming.

A thermo-electric style cooler is built into the analyzer cabinet. This system removes the condensable moisture that is typically found is baking oven gas samples. Methane alarm activates a red strobe and relay contact. Stainless steel wall mount cabinet is suitable for general purpose areas in baking production facilities. To remove particulate matter from the extracted sample gas, a heated filter is installed at the extraction point.

Oxygen Analysis PPM / Percent

In some processes, O₂ content is a critical factor. The process atmosphere may vary widely between start-up and in-operation. Sometimes the process cannot be started until the O₂ is purged down to ppm levels – an O₂ analyzer is usually required to verify this condition. Some heat treating atmospheres and some types of glass-making fit this description.

Electrochemical sensors are a reliable and economical way to measure O₂ at ppm and percent levels. However, these two levels require different sensors, and the ppm O₂ sensor cannot be exposed to percent O₂.

Challenge – measure percent O₂ and ppmO₂ in the same process using different sensors, without exposing the ppmO₂ sensor to percent O₂ levels.

Solution – We achieve this requirement by using the percent channel as the ‘controller’ to activate or deactivate the ppm channel. During deactivation, solenoid valves trap ppmO₂ gas in the ppm channel to avoid exposure to high O₂.

As the O₂ level comes down, the ppm channel is activated and an on-screen indicator message illuminates. The ppm channel can be protected automatically or manually depending on the customer’s preference.

Dual Background Hydrogen Analysis

Hydrogen is a significant capability that Nova has developed over the years. It is an important gas that has a presence or a role in many applications. One challenge in measuring H₂ by thermal-conductivity detectors is the interference effect that other gases have on its accurate measurement. Some gases will increase the H₂ reading, and others will decrease it.

We had an application recently that required H₂ measurement in the presence of two carrier gases. On some occasions, the carrier was nitrogen; other occasions, it was methane.

Challenge – provide an instrument that allows measurement of H₂ without analytical interference under two separate background gas conditions.

Solution – thermal-conductivity analyzer with two switch-selectable ranges; one for each background.

Range 1: 0 – 100 % H₂ in N₂

Range 2: 0 – 100 % H₂ in CH₄

This analyzer also had a receipt printer and a serial output with data-logging software.

Current versions of this type of instrument will have a touch-screen display, and some of the manual push-buttons will be eliminated.

Three-Channel Carbon Dioxide Analysis

People who research fire suppression systems are frequently interested in carbon dioxide (CO₂) analysis. They may be using CO₂ to blanket an area to stifle a fire. Or they may be burning something in a controlled environment and want to observe the effects.

Challenge – Different concentrations of gas may stratify at different levels in an enclosed area. Can we provide an instrument to simultaneously measure the CO₂ levels at multiple sample points?

Solution – In the past we have produced CO₂ analyzers with three entirely separate CO₂ channels. This allows the users to get a picture of what CO₂ levels are developing at different elevations in the space.

For this application, we have typically used our Model 302 Portable CO₂ Analyzer and modified it to essentially result in a 3-in-1 analyzer.

There are 3 separate SAMPLE-IN ports, pumps, flow meters, detectors, displays, and all other parts required to give 3 discrete and simultaneous measurements.

Current versions of this type of instrument will have a single touch-screen display with all three readings, and the manual potentiometers will be eliminated.

Please contact our Sales team for more information.

Or to provide us with more information about your application, please complete our Application Questionnaire and our Sales team will follow up with you promptly.

Sample Conditioning

Jan 2014 – For information about sample conditioning options for portable and continuous analyzers, go here.

If you need more information on Nova solution for tough applications, contact us here.