Hi. I’m Bonnie Crossland, Rosemount product manager for gas chromatograph (GC) technology and I’ll be your analytic expert today. I recently had an opportunity to write an article for InTech magazine and I’d like to share with you some of the ideas from that article.

mj-2016_web-exclusive-storyYou may be aware that glass production is one of the most energy intensive industries, with energy costs topping 14% of total production costs. The bulk of energy consumed comes from natural gas combustion for heating furnaces to melt raw materials, which are then transformed into glass. Additionally, glass manufacturing is sensitive to the combustion processes, which can affect the quality of the glass and shorten the lifespan of the melting tanks if not managed properly. Historically, the composition of natural gas has been relatively stable. However, dramatic changes in the supply of natural gas (including shale gas and liquefied natural gas imports) are causing end users to experience rapid and pronounced fluctuations in gas quality.

You may not have anything to do with glass manufacturing, however, this application is an excellent example of the impact of the combustion process on energy consumption in any industry – and the best ways to measure and control that process. Many companies in a wide range of industries faced with the problems of inconsistent quality in natural gas may not have considered gas chromatography as a viable solution for balancing air/fuel ratio due to the traditional complexities of the measurement. It’s time to look again. New developments in gas chromatography technology may make this approach the first choice for improving energy efficiency, and ultimately, process quality.

The efficiency of the furnace can be optimized for the air/fuel ratio when the composition of the incoming gas changes. This can significantly reduce energy consumption and provide substantial savings to the business in product quality and equipment life. Optimizing the furnace efficiency has traditionally been complex and costly. Next-generation gas chromatography, however, is changing that paradigm, providing a cost-effective, task-focused methodology that can be carried out by less technically proficient personnel than were traditionally required.

A major glass company in the southeastern U.S. is a heavy user of natural gas. However, the gas comes from multiple locations, causing a constant fluctuation of the BTU value. Because gas flow is adjusted based on the BTU value, knowing the precise measurement is essential. In addition, because gases with the same BTU operate differently through a burner, knowing the Wobbe Index is critical to quality.

mj-2016_we-fig-1When the company began employing a gas chromatograph to optimize its fuel quality, it found the traditional intricacies of gas chromatographs inappropriate for its application. Despite repeated training, its staff was unable to calibrate the instrument. New GC technologies designed specifically for natural gas optimization significantly reduced the complexity of operation. In new designs, all of the complex analytical functions of the gas chromatograph may be contained in a replaceable module, greatly simplifying maintenance. Features like auto-calibration make operation easier and more accurate, even for novice users. And unlike other analyzers that change the air/fuel ratio based on feedback after combustion, the GC offers a feed-forward control, where the air/fuel ratio can be changed based on the composition before combustion occurs in the flue. This can help stay in emission compliance and maintain energy efficiency with the GC.

The InTech article has a lot of other details on the need and process of optimizing combustion and the effectiveness of new generation GCs in meeting those needs. Gas chromatographs are used throughout the natural gas chain of custody (from wellhead to burner tip) to determine the gas composition for quality monitoring and energy content. For pipeline quality natural gas, the industry standard is the C6+ measurement method. If your company is a user of natural gas, you may already have GCs involved in your process. Using them to ensure the efficiency of your combustion and the ultimate quality of the product is just another vital addition. If you aren’t currently using GCs, let me know if you have any questions, or would like a demonstration, by leaving a comment HERE, or emailing me HERE.


By J. Patrick Tiongson, Product Manager, Emerson

At first glance, calibrating conductivity sensors may seem straightforward; however, many times, this is not the case. I’d like to share with you some of the various methods for calibrating contacting conductivity sensors and outline some of the potential issues that can accompany such procedures.

There are three main methods for going about calibrating contacting conductivity sensors: 1) with a standard solution, 2) directly in process against a calibrated referee instrument and sensor, and 3) by grab sample analysis. Understanding the fundamentals of each method, and the issues associated with each, can help make the decision on how best to calibrate a sensor.

Calibration with a standard solution consists of adjusting the transmitter reading to match the value of a solution of known conductivity at a specified temperature. This method is best when dealing with process conductivities greater than 100 µS/cm. Use of standard solutions less than 100 µS/cm can be problematic as you run into the issue of contaminating the standard with atmospheric carbon dioxide, thereby changing the actual conductivity value of the standard. For maximum accuracy, a calibrated thermometer should be used to measure the temperature of the standard solution.

If dealing with low conductivity applications (less than 100 µS/cm), in-process calibration against a referee instrument is the preferred method. This method requires adjusting the transmitter reading to match the conductivity value read by a referee sensor and transmitter. The referee instrument should be installed close to the sensor being calibrated to ensure you are getting a representative sample. Best practices for attaining a representative sample across both the process and referee sensors include using short tubing runs between sensors and increasing sample flow. Though usually not as accurate as calibrating against a standard solution, this method eliminates the need to have to remove your sensor from process, and removes any risk associated with contamination from atmospheric carbon dioxide.

The least preferred method of calibrating a contacting conductivity sensor is by analyzing a grab sample. This method entails collecting a sample from process and measuring its conductivity in a lab or shop using a referee instrument. Calibration via grab sample analysis is only ever recommended if calibration with a standard solution is not possible or if there are issues with installing a referee instrument directly in process. The collected grab sample is subject to contamination from atmospheric carbon dioxide and is also subject to changes in temperature when being transported. In other words, there are many potential sources for error in the final calibration results.

More information regarding calibrating conductivity sensors can be found HERE.

Have you been utilizing the best method for calibrating your sensors? Are there any challenges that you run into?


By Neil Widmer, Business Development Manager, Emerson Process Management

Sulfur plant tail gas incinerators are used to oxidize sulfur compounds that cannot be released directly into the atmosphere. These sulfur compounds include H2S, COS and CS2. Incinerators are operated at temperatures that are sufficient for oxidation of the sulfur compounds to SO2, as well as providing the required mechanism for proper plume dispersion. Sulfur plant incinerator control is typically based on a closed loop control on the fuel gas flow to achieve the required incinerator temperature. Natural draft dampers that are manually opened or closed, traditionally supply combustion air. Modern incinerator design incorporates forced draft combustion air. This allows closed loop temperature control where combustion air is provided based on the required ratio to fuel gas. Closed loop control based on excess oxygen can be used to optimize fuel gas control.

Optimizing Sulfur Incinerator Operation with an In-Situ Oxygen Analyzer

Figure1blogIdeal operation of these incinerators is to provide an excess of oxygen in the flue gas stream that ensures complete oxidation of all sulfur compounds to SO2. Sulfur plant incinerators are typically operated with excess oxygen levels of 6 to 10 percent. The recommended operating range for excess oxygen is 2 to 5 percent. Operating below 2 percent may result in insufficient oxidation of the sulfur compounds to SO2. This may result in a violation of the allowable concentrations of H2S, COS and CS2 allowed in the incinerator effluent. Operating above 5 percent excess oxygen will result in an excessive use of incinerator fuel gas. Figure 1 to the right illustrates the relationship between relative fuel demand, stack temperature and excess oxygen concentration.

RA.4000The most significant advantage of operating within the recommended range is two-fold: Operating above the minimum recommended 2 percent excess oxygen would ensure proper oxidation of sulfur compounds. Operating below the maximum recommended value of 5 percent excess oxygen will provide a reduction in fuel gas usage. An added bonus of operating with a decrease in excess oxygen is the reduction of CO2 (a greenhouse gas) emissions associated with a decrease in fuel gas consumption.

It’s possible to monitor excess oxygen concentrations within the sulfur plant incinerator by using the zirconium-oxide measurement principle. Zirconium oxide is an in situ measurement that provides a fast and reliable measurement of excess oxygen in the sulfur plant incinerator exhaust gas. To counteract the poisoning affect that SO2 has on standard zirconium-oxide sample cells, new sulfur resistant cells are available.

Summary of economic and environmental benefits:

  • Reduction in greenhouse gas emissions
  • Reduction of fuel gas consumption
  • Reduction in combustion air blower requirements

Analyzer Performance:

  • Accuracy 0.75% of reading or 0.05% O2
  • Withstands high sulfur process gases

To learn more about instrumentation that can optimize incinerator operation, click HERE.

How do you optimize oxygen levels in your combustion applications?


 

Hi. I’m Ruth Lindley and I’m happy to get the chance to tell you how to solve a significant problem in refining in a relatively simple and straightforward manner. The problem is ammonia slip.

TypicalNOxNitrogen oxides result from the combustion process in turbines, crackers, combustion engines, boilers, and other locations within a plant. NOX is a powerful pollutant, so it is important to control and contain NOX emissions. Both selective catalytic and selective non-catalytic reduction (SCR and SNCR) are techniques used worldwide to remove NOX. However, this process can result in a byproduct of unreacted ammonia, or ammonia slip. Continuous measurement and monitoring of ammonia slip can be a challenge to ensure sample integrity is maintained, especially in high-dust, high-temperature applications. But regardless of the complexity, to adhere to environmental guidelines, operators must balance using the precise amount of ammonia – not enough ammonia results in waste, too much can lead to emissions.

So how to solve the ammonia slip problem? The answer is QCL/TDL laser technology. (You may not have been expecting that!) In fact, capable, fast Rosemount QCL/TDL technology delivers the needed measurement precision (0–100 ppm) to ensure production is at its optimum and avoid overdosing issues that result in both economic and environmental problems and cost.

Quantum Cascade Lasers monitor ammonia slip to avoid the formation of damaging ammonia salts downstream or emission of 5100captionammonium chloride or gaseous ammonia, and the regulator fines and penalties that result. Here are some of the benefits of Quantum Cascade Lasers in this challenging application –

  • Interference-free monitoring of the presence of ammonia slip in the toughest environments
  • Thousands of measurements per second are recorded using patented laser chirp techniques to ensure identification of even trace levels of ammonia
  • Ammonia slip detection and insight into the efficiency of the plant’s NOX reduction system resulting from real-time measurement and analysis
  • Rugged, modular design delivers outstanding reliability and measurement stability in extreme operations
  • Monitoring of up to twelve critical component gases for all industrial applications, toxic gas detection, and plant-wide emissions monitoring
  • No consumables, no calibration, and no in-field enclosure or shelters reduce cost and simplify maintenance and upgrades

For additional information on the specific QCL/TDL laser products that might work for you, click HERE.

The QCL/TDL laser solution to ammonia slip may seem almost too good to be true – but it’s real and operating in plants worldwide. It’s time for all of us to adjust our thinking on the ammonia slip issue, accepting that there is a better way to overcome it efficiently, reliably, and cost-effectively.

Have thoughts or questions about QCL/TDL laser technology? Post them HERE!


By Amanda Gogates, Product Manager for Quantum Cascade Laser Analyzers, Emerson Process Management

You may have seen a few stories already on the innovative QCL laser technology. That technology has now been successfully implemented in Emerson’s Rosemount™ CT5100 continuous gas analyzer. It is the world’s only hybrid analyzer to combine Tunable Diode Laser (TDL) and Quantum Cascade Laser (QCL) measurement technologies for process gas analysis and emissions monitoring. The CT5100 provides the most comprehensive analysis available (down to sub ppm) for detecting a range of components, while simplifying operation and significantly reducing costs. The CT5100 can measure up to 12 critical component gases and potential pollutants in a single system – meeting local, state, national, and international regulatory requirements.

But if you’re thinking that the CT5100 is remarkable but “bleeding edge” technology that your application can’t afford – think again. The Rosemount CT5100 operates reliably with no consumables, no in-field enclosure, and a simplified sampling system that does not require any gas conditioning to remove moisture – truly “next generation” technology which chartsaves you money at every turn. The CT5100 is a unique combination of advanced technology and rugged design, and is highly reliable. Its patented laser chirp technique expands gas analysis in both the near- and mid-infrared range, enhancing process insight, improving overall gas analysis sensitivity and selectivity, removing cross interference, and reducing response time. This laser chirp technique produces sharp, well-defined peaks from high resolution spectroscopy that enables specificity of identified components with minimum interference and without filtration, reference cells, or chemometric manipulations.

The rugged Rosemount CT5100 analyzer features –

QCL-Image-CT5100-Ex-160420

  • Multi-laser, hybrid QCL/TDL configuration for up to 12 measurements simultaneously per analyzer
  • Accurate and sensitive gas measurement
  • Excellent linearity of response and repeatability
  • Fast and continuous gas measurements using the patented chirp technique
  • Low maintenance and low lifetime costs
  • No long-term drift due to inherent stability of spectroscopic measurement technique
  • Continuous health diagnostic reporting
  • Embedded ARM processor for fully autonomous operation
  • Modular architecture is easily serviceable and upgradeable in the field
  • Superior spectral analysis to eliminate cross-interference and improve measurement accuracy
  • Intuitive, simple front-panel user interface allows access to all instrument functions

Give your Emerson representative a call and discuss the potential of the CT5100 in your process gas analysis, continuous emissions monitoring, and ammonia slip applications. This could be a whole new solution to some costly problems. Click HERE for more information on the CT5100.