Why Use Process Analytical Spectroscopy for Real-Time Monitoring?
Traditionally, absorption spectroscopy has been used in laboratories to perform the precise analyses of samples. In recent years, as electronic circuitry and optical components have become more refined, a more robust portion of the electromagnetic spectrum – UV/VIS/NIR – has emerged for use in process analytical technology. No other technology matches the acquisition speed and the range of measurements returned by a fiber optic-based dispersive grating spectrometer. A comprehensive set of data that takes hours of laboratory analyses to acquire can be available in about a minute with a process spectrometer.
Process Analytical Technologies (PAT) have been field proven for almost three decades. It is typical for a Guided Wave scanning spectrometer running 24/7 to last more than 10 years with >99% uptime. The maintenance requirements for process spectrometers are also minimal in comparison to other monitoring techniques (for example, process gas chromatographs and online titrators). The return on investment and the low cost of operation makes Guided Wave analyzers a sensible and proven choice.
Near-infrared (NIR) spectroscopy is a non-destructive technique that can provide fast, accurate results of process conditions. NIR Spectroscopy is able to achieve real-time monitoring of multiple constituents in the process by illuminating the sample with light and analyzing how the light interacts with the sample. Spectroscopy achieves this without the high maintenance costs or the extensive upkeep considerations typically associated with gas chromatography (GC). Additionally, optical technology often eliminates the costly sample systems and fast loops needed for process gas chromatography.
NOTE: GC analyses can have significant annual costs associated with routine maintenance, column degradation, and carrier gas consumption. Such continual costs can be greatly reduced by replacing it with our Guided Wave inline spectrometer-based analyzer.
A Single-Supplier Solution For Impurity Monitoring In Fuel-Cell Hydrogen
Global efforts to reduce the impact of harmful emissions on the environment have increasingly focused on lowering carbon emissions. The key to meeting this challenge lies in replacing fossil fuels with alternative, renewable fuel sources, particularly to power vehicles.
Fuel cells offer a uniquely flexible solution in this market and can be used for a wide range of applications, powering systems from laptop computers to utility power stations. The move to a hydrogen economy is widely regarded as the next step in the global transition towards a zero-emission energy sector. A hydrogen fuel cell uses chemical energy to cleanly and efficiently produce electricity; the only byproducts are water and heat. It can also be combined with electric motors to power a zero-emission vehicle.
While most hydrogen (H2) today is still produced from fossil sources, an established H2 infrastructure allows a future seamless transition to renewable and truly carbon-free H2 production. Fuel cells are also far more efficient than conventional combustion engines while offering a similar range (typically, about 500-700 km). H2 can also be refilled quickly at a fueling station, avoiding the delays of charging a battery-electric vehicle.
However, the performance of a fuel cell is dependent on the purity of the hydrogen. There are multiple impurities that can affect the fuel cell, and their presence and concentration levels depend largely upon the method used to generate the H2. For example, most hydrogen is produced through steam methane reforming. This process can generate several contaminants ranging from methane and moisture to carbon monoxide and carbon dioxide (CO2). If H2 is created through electrolysis, splitting water into hydrogen and oxygen, then moisture and oxygen are the most common contaminants. Additionally, many impurities can come from the atmosphere, mostly nitrogen, oxygen, and moisture.
Eliminating impurities from H2 altogether is not practical. Maintaining an efficient fuel cell requires the presence of these contaminants to be limited to specific levels, set by international purity standards such as ISO 14687 or SAE J2719.
It is essential to monitor the wide range of impurities listed in the table above to prevent performance being compromised, or worse, irreparable damage to the fuel cell. In the past, a monitoring solution for H2 purity involved a complex setup using as many as seven different analyzers from multiple providers, with no integration. A typical arrangement requires:
A gas chromatograph for total sulfur and total halogenates
Another gas chromatograph for helium, nitrogen & argon, and methane/THC
An electrochemical analyzer for oxygen
An FTIR to measure CH2O2, CO and CO2
Three separate CRDSs, measuring water, ammonia, and CH2O
Process Insights provides a full portfolio of solutions for monitoring hydrogen purity throughout its supply chain, from production, through transport and storage, to fueling. The contaminant detection limits of these instruments are ideally suited to qualify H2 for compliance with global purity standards. The real benefit, however, lies in Process Insights’ total solution. Only three analyzers are required, and these can be fully integrated into one single-provider system.
Sulfur & THC Multi-Species GC Analyzer – for total sulfur and total hydrocarbons
The Prismatic 3 multi-species Cavity Ring-Down Spectroscopy (CRDS) analyzer allows simultaneous detection of up to four impurities with wide dynamic ranges, delivering simple, real-time, direct measurements. Highly reliable and with low maintenance requirements, the Prismatic 3 is ideal for remote operations and has a low cost of ownership. Tiger Optics’ analyzers are used to support fuel-cell hydrogen quality control by organizations including the Korean Gas Safety Corporation (KGSC) and California’s Division of Measurement Standards and is approved by ISO.
The MAX300-LG is a compact benchtop mass spectrometer that delivers complete, real-time sample analysis from 100% concentration down to parts-per-billion (ppb) levels. It is supported by our Extrel easy-to-use Questor5 process control software, which is designed for continuous gas monitoring with automated calibrations, analysis sequences, and data outputs.
The combination of Process Insights’ Prismatic 3 analyzer and MAX300-LG mass spectrometer with a Sulfur & THC GC Analyzer to provide the remaining measurements provides a powerful solution for monitoring contaminants in fuel-cell hydrogen. This system dramatically reduces the number of instruments required for measuring hydrogen samples and reduces the cost of manpower and operation through ease of use and low maintenance needs. It also means operators only deal with a single provider, reducing the complexity of ordering, integration, and usage.
Cryogenic gases are normal atmospheric components which have been liquefied, separated and purified.
Although they may be supplied as a high-pressure gas, most are shipped to the customer in a liquid state and vaporized on site. The primary cryogenics are O2, N2, Ar, H2 and He are supplied in much smaller quantities.
Cryogenic gases are purchased for their particular properties. They may be used as an inert blanket, in a chemical reaction or as a catalyst. Due to this usage, they are sold in various degrees of purity. Moisture (H20) is obviously an impurity, although on a very small scale. Moisture levels will, typically, be in the 0-5 PPM range.
Due to the purity of the gas and cleanliness of the application, there are few problems with this application. The sensor should be in a bypass after the vaporizer and not directly in the flow. This will warm the sample and ensure that the flow past the sensor is not excessive. Learn more on dew point measurement.
Parts-Per-Trillion Moisture Detection in Electronic-Grade Bulk Gases
The semiconductor market is seeing a new era of innovation, with new applications fueling demand for advanced semiconductor devices that put more stringent requirements on reliability, power handling capability and power consumption, while packing more functionality into a smaller package and decreasing technology nodes.
Among these demanding applications are increasingly more powerful smartphones and tablets that aim—at the same time—to improve battery life. More recently, automotive sensor systems, the Internet of Things (IoT), the next generation of wireless communication (5G), and smart power grids have emerged as applications with enormous expansion potential over the coming years and decades. Future self-driving vehicles, for instance, require massive amounts of computing power to process the input from cameras and sensors in real-time; and the necessary high-performance processors must be both reliable and power efficient.
The Demand for Higher-Quality Gases and Better Analytics To meet the challenges of these new applications, the semiconductor industry’s International Roadmap for Devices and Systems (IRDS) outlines manufacturing quality as one key aspect; therefore, semiconductor device manufacturers are implementing more stringent control into all aspects of the manufacturing process, from the cleanroom environment and the wafer processing tools to the raw materials used for production, many of which are gases. Consequently, improved gas quality control is one of the most important measures that are employed by semiconductor fabs to increase yields and reduce failure rates.
With the need to monitor and ensure stricter and more consistent gas quality comes a demand for more sensitive and accurate analytical technologies. At the same time, speed of response has become more important as well, as fab operators rely heavily on real-time process control to
In many state-of-the-art semi fabs, Cavity Ring-Down Spectroscopy (CRDS) analyzers are the gold standard for ensuring quality of the major bulk gases that are used in the manufacturing process, which are typically N2, CDA, O2, H2, Ar, and He.
Hydrogen Chloride (HCl) is a major atmospheric pollutant associated with the combustion of fossil fuels, such as coal and heavy oils, and also with a number of manufacturing processes, including cement production.
HCl in the atmosphere has an adverse effect on both human health and the wider environment. The inhalation of even low concentrations of HCl can cause irritation of the respiratory tract in healthy individuals and exacerbate symptoms associated with conditions such as asthma and emphysema.
Dissolved HCl is a contributor to acid rain pollution, the results of which include damage to building materials and reduced crop yields. Atmospheric HCl pollution is also a factor in the production of photochemical smog. The economic impact makes the reduction of HCl pollution a priority for regulators and industry. HCl is generated by multiple industrial processes, with combustion of coal and oil for household and industrial power generation as the primary source. Here, chlorides present in the fuel are converted to HCl in the combustion process and emitted with other by-products. In addition, industrial processes emit HCl as a result of chlorides present in raw materials that are converted to HCl during production. In cement production, for instance, raw materials, including calcium carbonate, silica, clays, and ferrous oxides, all contain chlorides, resulting in generation of HCl.
Regulators worldwide dictate strict emissions limits for many atmospheric pollutants, including HCl. In the United States, the Environmental Protection Agency (EPA) has recently reduced emissions limits to further lessen the impact of the issues. These emissions limits require HCl emitters to monitor and report the level of the gas present in stack emissions and to ensure that steps are taken to guarantee that emissions fall below the specified limits. This may require the emitter to either refine their process, via the use of cleaner fuels, for example, or to add abatement technology downstream of the process to reduce emissions of HCl.
Current analytical methods for HCl CEM applications include GFC/NDIR, FTIR, and cross-stack TDLAS. These methods have, to date, been adequate to monitor HCl emissions, based on existing emissions limits. The detection limits for some of these techniques will not be sufficiently low, however, to meet the revised limits, and so alternative techniques will be necessary.
CRDS gas analysis technology offers the performance and range to cope with these regulations, delivering accurate measurements at levels far below the new limits in diluted stack gas.
Monitoring Airborne Molecular Contaminants in Cleanrooms
Airborne Molecular Contaminants in Cleanrooms
The dust-free and controlled environment of a cleanroom is vital to prevent product failure in semiconductor manufacturing but controlling particulates in cleanrooms is not nearly sufficient to protect semiconductor devices that feature structural sizes on a molecular level. Micro-particles are the main source of physical contamination, but modern filtration systems for air supply, cleanroom attire and specialized surface materials have been successful in keeping particle contamination under control.
There are, however, molecular contaminants, which can range from small inorganic molecules like acids and bases, to more complex organic species like VOCs. These molecules are known to cause chemical contamination (i.e. they react with the materials and surfaces of the semiconductor devices to cause oxidation, unintended doping, dislocations, and more).
This class of contaminants is collectively known as Airborne Molecular Contaminants (AMCs). They are harder to control than particles. Firstly, the molecules are much smaller than particles and require more advanced chemical filtration of the cleanroom air. Secondly and more importantly, however, many AMCs are created within the cleanroom itself. For instance, HF is used for wafer cleaning within the process, and NH3 is emitted naturally by any person present in the cleanroom. As feature sizes have decreased over the decades, both devices and equipment became more and more susceptible to significant damage from AMCs. They can have various detrimental effects: Acids, such as HF or HCl, can cause micro-corrosion and accelerate oxidation. Bases, such as NH3, can cause hazing and attack coatings on the optics of UV lithography equipment. Hydrides, such as AsH3, PH3, or B2H6, can cause unintended doping, which can dramatically impact a devices functionality.
Monitoring AMCs is Key to Contamination Prevention Because many AMCs are generated within the cleanroom, they cannot be completely avoided, even though wafers are shielded as much as possible from exposure nowadays, e.g., by transporting them in closed pods (FOUPs) between process steps. Precise monitoring of the cleanroom environment for these molecules has emerged as a key for semi fabs to further mitigate the threat of AMCs. By immediately detecting the presence of harmful molecules, engineering controls can be implemented to protect devices and processes from exposure.
Due to the low concentration of AMCs and the need for fast detection, measurement instruments have to fulfill stringent requirements. As a result, ultra-sensitive laser-based analyzers have emerged as the primary class of instrument used to detect small AMCs, such as HF, HCl or NH3. Semiconductor fabs require all of these molecules to be measured at levels below 1 part per billion (ppb) with a response of 1-3 minutes to any presence of molecules. More importantly, the instruments readings have to return to baseline as fast as possible after the molecules’ presence is eliminated to minimize delays in the manufacturing process. The International Roadmap for Devices and Systems (IRDS) even calls out detection requirements below 0.1 ppb as part of the future technological challenges.
Introducing our NEW T-I Max Next-Generation AMC Monitors To address this challenge, Process Insights manufacturers the TIGER OPTICS™ T-I Max™ seriesof cleanroom analyzers for detecting AMCs like HF, HCl, and NH3 with unprecedented speed and sensitivity. The T-I Max uses powerful Cavity Ring-Down Spectroscopy (CRDS) Technology but uses an all-new electronic and optical platform that enables lower measurement noise and up to ten times faster measurement rate. This platform takes CRDS to the next level and dramatically lowers detection limits compared to previous generation analyzers.
Cost-Effective Purity Analysis in the Cryogenic Air Separation Process
Did you know you can improve safety and your process efficiency by using CRDS gas analyzers?
CRDS analyzers offer many opportunities to improve the air separation process by saving time and money and alerting plant operators quickly in case of unsafe impurity levels. Key advantages of using CRDS gas analyzers include:
Cryogenic Air Separation Cryogenic air separation units (ASUs) are the gas industry’s workhorses for the production of gaseous and liquid high purity nitrogen, oxygen and argon. The cryogenic process can be modified to manufacture a range of desired products and mixes.
Controlling Impurities to Ensure Safe ASU Operation Following compression, the air pre-treatment step consists of cooling and purification to remove process contaminants, such as H2O, CO2 and others. The most common purification methods are Temperature Swing Adsorption (TSA), which exploits the difference in adsorption capacity of adsorbents at different temperatures, and Pressure Swing Adsorption (PSA), which operates similarly via pressure variations.
Monitoring Gasification with a Mass Spec Gas Analyzer
Research in the field of biomass gasification is increasingly important as industry continues to find new uses for syngas. At the Energy & Environmental Research Center (EERC) an Extrel MAX300-RTG process mass spectrometer was used to monitor the exit stream of a Fluid Bed Gasifier. The quadrupole mass spectrometer provided fast, quantitative analysis of the syngas composition.
Over the last several years, concern about the economic and environmental impact of traditional fossil fuel combustion and petrochemicals has led to a search for viable alternatives with gasification emerging as a powerful technique for generating fuel and hydrocarbons. The gasification process makes use of materials such as coal, biomass, and waste to produce synthesis gas, or syngas. Syngas is a combustible mixture of hydrogen, carbon monoxide and carbon dioxide that generally contains a small amount of methane and some trace contaminants. Syngas is used as a fuel source to generate power and heat, or converted into products like hydrogen, for use in fuel cells or fertilizer generation, or liquid fuels via a Fischer-Tropsch reaction.
Gasification and chemical processes utilizing syngas rely upon the ability to obtain information about the composition of the gas stream exiting the reactor. The MAX300-RTG is a 7th generation process mass spectrometer capable of performing quantitative analysis on a wide variety of compounds at concentrations ranging from 100% down to 10 ppb. The 19 mm quadrupole mass filter used by the system allows for high analytical repeatability and long-term stability.
The MAX300-RTG demonstrated that it has the flexibility to quickly characterize and quantify syngas mixtures. It has the sensitivity to detect trace components at ppm levels and below, and the speed to perform each measurement in under 0.4 seconds. The ability to analyze the complete array of syngas components exiting the gasifier, from 100% down to ppm levels, makes the MAX300-RTG an instrument capable of replacing complicated analysis systems involving multiple devices and technologies. The speed of the mass spectrometer means that the MAX300-RTG can be automated to monitor gas composition at several sample points, delivering a complete set of concentrations at 20 seconds per point.
At the EERC, additional sampling at the ports downstream of the reactor could yield important insight into the operation and efficiency of the fixed beds, or be used to analyze hydrogen membrane separation, or a Fischer-Tropsch product. The speed and flexibility of the MAX300-IG, combined with the capability to run 24/7 in rugged and hazardous industrial environments, make it ideal for monitoring production scale gasification and any associated chemical processes downstream. At large facilities that utilize syngas, like ammonia plants, the MAX300-RTG and its predecessors have set the standard for analyzer automation and process control over the last several decades.
Total Sulfur and Total Nitrogen in Fuels and Chemicals
Regulatory agencies around the world have been implementing increasingly stricter fuel emissions guidelines over the past decades to limit air pollution. Regulations such as the American Tier III, European Euro 6 or the Indian Bharat VI set quantitative limits on the permissible number of specific pollutants that can be released during combustion.
Sulfur and Nitrogen are both controlled under these regulations due to the health and environmental impact of their oxides: Sulfur Dioxide (SO2), Nitrogen Oxide (NO) and Nitrogen Dioxide (NO2), commonly referred to as NOx. In order to measure sulfur and nitrogen content in fuels, chemicals and petrochemicals, Process Insights delivers the XT-2000 laboratory analyzerfor both Total Sulfur (TS) and Total Nitrogen (TN) measurements.
The XT-2000 utilizes patented Excimer UV Fluorescence (EUVF) Technologyfor TS measurement and proprietary Chemiluminescence (CL) technology for TN measurement offering exceptional sensitivity that does not require a vacuum pump minimizing maintenance requirements and improving analytical stability. The XT-2000 provides accurate, precise and fast analysis for a broad range of samples with a typical analysis time of 3 minutes or less.
The XT-2000 demonstrates outstanding linearity for 0-100 ng/μL TS/TN in isooctane standards with excellent 0.9998 and 0.9995 correlation for both TS and TN measurements. Results for various fuels and chemicals presented on the following page show TS and TN content from ppb level to 31.45 ppm/wt (TS) / 12.48 ppm/wt (TN). All samples were analyzed 5 times with an RSD of 2% or better for samples above 1 ppm.
Trace Sulfur in Butane and Other Gas or LNG Applications
Increasing need for Total Sulfur trace analysis in gas and LNG products
This remarkable online process analyzer incorporates our patented Excimer UV Fluorescence (EUVF) Technology and is specifically designed for measurement of Trace Total Sulfur content in applications that require the ultimate in low-level sensitivity, such as polymer-related applications.
One application where our TraceS-1000 has demonstrated exceptional analytical performance is the measurement of total sulfur in butane at the ultra-low range of 0-1000 ppb/vol. Acquired test results reflect excellent linearity, precision and long-term stability for this extremely low range. Analytical results represented were obtained utilizing an oxygen/argon blend for combustion.
The TraceS-1000 provides unparalleled sensitivity and rapid response to concentration changes with a typical analysis time of only 180 seconds. Instrument operation is simplified with intuitive and user-friendly software, with an added feature that allows data averaging for enhanced analytical precision. Eight-hour repeatability using a sulfur dioxide (SO2) permeation tube for sulfur addition to instrument-grade butane demonstrated a SD of 14.7 ppb at 205 ppb/vol. concentration or 7.17% RSD. Using the moving average feature, a 3-run analysis (9-min. response time) further improved repeatability, yielding a SD of 8.5 ppb or 4.16%. Various concentrations run for linearity characterization reflect rapid response, outstanding repeatability and excellent linearity with a 0.9965 correlation.
