By Bonnie Crossland, Product Manager, Gas Chromatographs, Emerson Automation Solutions
As you may know, by January 30, 2019, 40 CFR Part 63 requires that petroleum refinery owners or operators of flares used as control devices for emissions points must meet the requirements of §63.670, regardless of the construction date of the flare. The regulation is part of the 1990 Clean Air Act that regulated emission standards for hazardous air pollutants (HAP) and is in addition to 40 CFR 60 Subpart Ja requirements. 40 CFR Part 63 regulations require determining the concentration of individual components in the flare vent gas within 15 minutes or direct monitoring of the net heating value of the flare vent gas at standard conditions.
I’m happy to tell you that Emerson Automation Solutions has developed two standard solutions that are compliant with 40 CFR Part 63 using its Rosemount 1500XA gas chromatograph (GC).
Why use a GC? Generally, you can consider three possible approaches when trying to meet petroleum refinery flare requirements – a calorimeter, a mass spectrometer, or a GC. A calorimeter is a relatively low-cost instrument, the measurement principle of which is burning the gas and measuring the heat generated. It has analysis time in the seconds range and simple maintenance, which all sounds very desirable. However, it requires a shelter for outdoor use, which adds significantly to its cost, and most important, it provides no information on what’s happening in the process or what’s going up the stack. Without composition information, there’s no way to determine which unit is generating the flare gases, which limits your response to a flare event.
A mass spectrometer provides individual component concentrations within the flare but at a very hefty price. Likewise, it requires a shelter, and is very difficult to maintain, often requiring a calibration gas for every component as well as a multicomponent blend. It usually requires monthly adjustments with notoriously high operating costs.
Which brings us to the GC solution. Like the mass spectrometer, the GC provides individual components (including isomers) within the flare but without the high price. The Emerson GC specifically requires no enclosure (saving even more money), it’s easy to maintain with simple thermal conductivity detectors (TCDs) for this application, provides information on what’s happening in the process through its easy-to-use software, and it provides updates well within 40 CFR Part 63 requirements.
Emerson Rosemount’s 1500XA gas chromatograph offers the greatest flexibility in measuring, calculating, and recording the individual component concentrations present in the flare vent gas. Emerson is offering two standard 8-minute solutions using the Rosemount 1500XA with multiple TCDs to meet the requirements of 40 CFR Part 63, Subpart CC (Refinery MACT 1) and 40 CFR Part 63, Subpart UUU (Refinery MACT 2). Solution 1 looks at hydrocarbons, H2S, H2, CO and CO2, and Solution 2 adds benzene detection. Custom solutions that measure, calculate, and record operators’ specific flare compositions are also available.
A GC provides an efficient and cost-effective approach to meeting the 40 CFR Part 63 requirements which every petroleum refinery plant is facing. If you’d like to discuss the possible implementation in your plant, give me a call at 713.396.8832, or contact firstname.lastname@example.org.
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.
You 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.
When 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 Bonnie Crossland, product marketing manager – gas chromatographs, Rosemount Analytical
Whether your gas chromatograph (GC) is used for custody transfer measurement or process control, it is critical to know your GC is providing accurate data and operating as it should. Validation is the testing of the correct calibration and operation of the GC. Many times we have heard customers say they run the calibration gas as an unknown to validate the GC – however, this is not an effective method. This only shows that the GC is doing what it is told. The GC will always read what it was forced to read in the morning calibration run. If the GC is set up incorrectly, has an issue, or the calibration gas blend is bad, the daily calibration may hide the issue and result in inaccurate analysis for the sample stream.
The validation of the GC can be completed in three steps:
Validating the operation of the GC for the previous period is done by checking alarm logs, event logs, and un-normalized total trend for the past 30 days. Reviewing the logs will yield clues as to whether the GC was running correctly. All alarms during the period should be investigated and the cause determined before moving to step 2.
Validating the current accuracy of the GC is done by confirming that the As Found calibration is correct, and then observing the correct operation and repeatability of the GC. Check the latest calibration report to be sure that the calibration gas concentrations entered into the GC match the certificate of the calibration gas cylinder. For natural gas applications, you will check the calibration report for Response Factor Order, Response Factor Deviation, and Retention Time Deviation. Once the existing calibration of the GC is confirmed to be accurate, run the GC through a calibration cycle. Check the results of the analysis of the calibration gas before and after the calibration cycle for repeatability. If everything looks good, move onto step 3.
The third and last step is to check for changes in operation that may affect future reliability of the GC. This is best accomplished by checking the retention times of the individual components peaks over the last 30 days. Overtime, retention times gradually increase from contamination of the analytical flow path. This is called Retention Time Drift and it can cause two issues – incorrect peak detection and incorrect component separation. The current calibration chromatogram is compared to the chromatogram from 30 days ago to assess the amount of drift that has occurred. This information is used to make a judgment on the likely amount of drift to occur over the next 30 days. If the drift will not impact peak detection or component separation, validation is completed. If the drift will impact peak detection or component separation, the GC should undergo planned maintenance during the next 30 days.
For more information on validating the operation of your gas chromatograph, click HERE to view the recorded webinar, “Validating the Operation of Your Gas Chromatograph,” the first in a new series of FREE webinars from Rosemount that we’ve prepared to help you get optimum ROI from your gas chromatographs. This new educational webinar series is called “Maximizing Your Gas Chromatograph’s Capabilities” and is hosted by Emerson’s top analyzer experts who will be covering the most critical aspects of the GC, sharing best practices, and addressing users’ frequently asked questions and challenges faced in the field.
Click HERE to register for this FREE new webinar series today! Next ones up include:
And if you end up missing any, recorded versions will be available for all.
We’d like to invite you to a new series of webinars that we’ve prepared to help you get optimum ROI from your gas chromatographs. The first of these webinars is coming right up – and they’re FREE – so sign up now so you don’t forget!
This new educational webinar series is called “Maximizing Your Gas Chromatograph’s Capabilities.”
Hosted by Emerson’s top analyzer experts, five webinars have been scheduled throughout the year to cover the most critical aspects of the gas chromatograph (GC), share best practices, and address users’ frequently asked questions and challenges you face in the field.
The first webinar, “Validating the Operation of Your Gas Chromatograph” is taking place on Feb 11th (details below), and will teach you how to verify the measurement accuracy of the analyzer at the time of testing and confirm that your GC continues to operate to the desired specifications between validation periods.
“Validating the Operation of Your Gas Chromatograph”
DATE: Thursday, February 11, 2016
TIME: 10:00am CST
DURATION: 60 minutes
Who should attend this webinar?
Measurement Engineers, Operations and Process Managers, Maintenance Technicians.
ADDITIONAL FOUR WEBINAR TOPICS AND DATES:
We hope you’ll be able to join us for this first information-packed webinar and please feel free to pass on this information as well.
About the Presenter
Shane Hale is the Director of Product Management for Rosemount Gas Chromatographs. With nearly 20 years of experience in the gas analysis industry, Shane is valued as one of the leading experts in his field, often invited to give lectures on chromatography.
By Ruth Lindley and Jeff Gunnell
With a range of technologies on the market for gas analysis, it can be a challenge to know which is best suited to your particular measurement requirement. This blog gives you a guide to choosing between two popular measurement techniques: gas chromatographs (GCs) and quantum cascade laser (QCL) analyzers, as with the recent acquisition of Cascade Technologies, Emerson can now offer QCL technology alongside its existing range of GCs. Both techniques offer excellent sensitivity and accuracy, but depending on application and measurement needs, one or the other will be preferred.
The purchase price of QCL and GC analyzers are similar and both offer multicomponent capability. The main way to choose between the two techniques is by the analysis required for the particular application. GCs are an excellent general purpose analyzer. They can measure liquid samples as well as gases and a wide range of molecules – both large and small. They can separate out complex mixtures and often measure the concentrations of isomers. In principle, dozens of components can be measured. QCL can typically measure up to 12 components per analyzer, but they all must be small gaseous molecules such as CO, ammonia, or hydrocarbons up to C4s. As such, for liquids and larger gaseous molecules, or for very large numbers of components in a stream, a GC is the correct choice.
Sometimes the speed of analysis is important in an application, and in that case, QCL has a clear advantage. In a QCL, the sample flows through a measurement cell where laser beams continuously analyze the the gas. The response time depends on how long it takes to flush the cell, typically <10 seconds to get to 90% of a step change, so the output is effectively continuous and real time. GCs on the other hand work on the principle of injection followed by analysis. Cycle times for a GC vary
from 1 minute to over 15 minutes, depending on the application, and thus the concentration data is periodic rather than continuous. For applications where fast, continuous measurements are required, QCL is therefore the preferred technique.In terms of sensitivity and dynamic range, QCL can offer better performance than GC. QCLs can measure down to low ppb concentrations for some compounds and offer a dynamic range from ppb through to percent concentrations in one analyzer by using multiple pathlengths or spectral lines of varying strengths. GCs are often used for measuring the entire composition of a sample and can measure down to ppm concentrations while also measuring the majority component up to 100%. However, to reach ppb measurements along with high percent level measurements in a GC usually requires separate injection and column trains, making for a more complex and expensive analyzer. So if high sensitivity is needed or there’s a wide dynamic range (for example for online purity measurement with the ability to follow process upsets), then QCL is the better option. If every component in the sample (including the background) needs to be measured, a GC may be more suited.
On cost of ownership, QCL is usually better than GC. GCs require a carrier gas, typically hydrogen, helium, or nitrogen. These are not needed by QCL analyzers, meaning that the cost of ownership, due to the use and management of consumables, is higher for GCs. QCLs inherently have a very stable calibration and they can often carry out validation and calibration checks in real time, using the process gases which are being measured. This is due to the way that spectra are obtained and analyzed, and consequently, checks using injected test gases may only be required every 12 months for QCLs. For GCs, it is more usual to carry out validation checks every few weeks. So if low cost of ownership is essential, then QCL is favorable. If the required measurements can be made by QCL this is likely to be the preferred choice due to lower cost of ownership and reduced maintenance requirements.
The table below gives a summary of the types of applications and measurements commonly encountered for gas analysis and the suitability of the GC and QCL technologies to each.
QCL and GC analyzers are both excellent options for industrial gas analysis and can be utilised across a range of applications and measurement points. The differences in the detection methods can make one or the other better suited to a particular application, and the table above is a guide to selecting the best fit to your application.
The Emerson sales team will be able to further assist in determining the best analytical method for your needs. Please click HERE for find out more information on QCL analyzers, and HERE for more information on gas chromatographs.