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in-line Cascade laser spectrometer for process control

Periodic Reporting for period 2 - iCspec (in-line Cascade laser spectrometer for process control)

Reporting period: 2016-10-01 to 2018-09-30

In the future, the petrochemical industry will be able to measure and control the composition of gas streams in real time thanks to a new measurement technology. It will allow production plants to be controlled more closely, to set their product quality more accurately, and to increase their output. At the same time costs and the environmental impact of waste materials disposed will be reduced. To make this vision become true a laser spectrometer that analyzes gas mixtures has been developed within iCspec. As a project result a new Mid-Infrared laser-based demonstrator gas analyzer has been tested lately at Preem, Sweden’s largest fuel company measuring the seven hydrocarbons methane, ethane, propane, n-butane, iso-butane, n-pentane and iso-pentane.
Analysis of complex gas compositions is usually done by process gas chromatographs, which requires up to several minutes depending on the gas matrix. Conversely, a laser spectrometer enables measurements to be taken directly in the gas flow or in a bypass line in real time. With less than 3 seconds response time the iCspec demonstrator impressively confirms the real time capability of laser-based multi-gas analysis. The laser technology also incurs lower operating expenses than existing technology.
Laser spectrometry exploits the fact that every light molecule absorbs particularly specific wavelengths. Although laser spectrometers that register individual molecules already exist, no solution was yet available that is capable of recording many industry-relevant gases simultaneously using a single laser module as light source.
Achieving this needs a laser source that ideally covers the required infrared fingerprint range. The new spectrometer uses semiconductor laser arrays that can be controlled to enable examination of both absorption lines with single sharp molecular absorption lines and broad absorption features. Evaluation poses its own particular challenges, since the measurements provide absorption spectra from many different molecules strongly overlapping. Spectral models based on physical parameters as well as neural networks have been applied successfully for accurate data analysis.
The above mentioned pilot application is not the only one for the new technology: It will also be suitable for emission monitoring, breath analysis and even more. Likewise, when it comes to analyzing fluids, solid matter or biological tissue laser sources are far superior to the incandescent emitters currently used in spectrometers.
Interband Cascade Laser (ICL) in the 3 – 5 µm spectral range:
For the ICL based sources, two approaches were investigated: Mode-locked ICL comb sources and ICL DFB array sources. ICL-arrays have been provided successfully for the target wavelength range. These devices were incorporated in the demonstrator hydrocarbon gas analyzer. ICL-array devices will be commercialized by nanoplus. These sources will address emerging new markets without competing with existing devices and markets due to their unique design and broad wavelength coverage.
Quantum Cascade Laser (QCL) in the 6 – 12 µm spectral range:
The main objective for the QCL-array technology developed by mirSense was the realisation of an array of single mode emitters of QCLs emitting in continuous wave at room temperature at 6.8 µm. Finally in the project this array has been successfully manufactured accessing the target wavelength. Full integration with the array, an integrated beam combiner and the ASIC for controlling operation could not be completed due to delays during the project. mirSense will continue the development of the devices and commercialize them.
Demonstrator C1-C5 gas analyzer based on ICL-, QCL-spectrometer:
The main objective of the project was the provision of a laser-based demonstrator hydrocarbon analyser. The ICL-array based C1-C5 spectrometer demonstrator has been developed successfully and tested in the crude oil distillation stage of the Preem refinery in Lysekil/Sweden. Moreover a cross duct in-situ demonstrator SO2/SO3 analyser has been developed and tested as well as an open path hydrocarbon emission monitor. Products for the demonstrated applications an even more will be launched by Airoptic in the coming years. Airoptic expects to reach >900 units/year by 2023 at the price of 18 kEUR and 23 kEUR for SO2/SO3 and C1-C5 respectively. Due to the missing QCL-array module this objective could not be achieved. However all the building blocks required for the demonstrator have been provided, a fully functional QCL-laser spectrometer and the data evaluation method which allows completing the HC analyzer as soon as the final QCL-array module is available. The new PAT can be used for process control in different application areas as e.g. in the oil and gas industry, the petro-chemical industry, for combustion and emission monitoring, for purity of gases. Siemens will follow the route to fully exploit all business opportunities based on this innovative PAT.
Currently the composition of gas mixtures is identified by extractive gas chromatographs with known disadvantages. Extractive analyzers employing fast detection methods will significantly decrease the maintenance costs and reduce waste and pollution. As laser based analyzers provide very short response times, excellent accuracies, afford minimum maintenance, and are resistant to contaminations of the gas stream, they become the most favourable choice for real time gas analyzers.
The outstanding capabilities of these new analyzers are based on three main developments of the iCspec project: (1) the development of widely tunable laser sources not available before the project, (2) the integration of these sources into industry grade analyzer systems and (3) the development of novel data evaluation algorithms. The technologies developed within the project were combined and incorporated in a demonstrator gas analyzer for the hydrocarbons methane, ethane, propane, n-butane, is-butane, n-pentane and iso-pentane. The new analyzer technology demonstrated its capabilities in a field test at the crude oil distillation stage of the Preem refinery in Lysekil/Sweden. The highlights are the short response time of <3 sec, compliance with specified accuracy, the small form factor (19” housing) allowing for fast installation, no need for consumables and low power consumption. With the performance demonstrated the new analyzer technology marks the leading edge of the technological progress.
The features of the new PAT will a have positive economic effects for the user, increase the safety for workers as well as impact on ecology. The highest impact will have the short response time of the analysis, which will speed up the process control loop, optimize the product quality and minimize waste. It will make it possible to run the process closer to its optimum and reduce the margins for safe operation. The laser analyzer will significantly reduce maintenance costs. Moreover, neither carrier gas (H2 or Helium) nor expensive calibration gas is required any more. It will also lead to decreased installation costs since it will be mounted close to the sample take off point without complex sample gas conditioning. The measurement will also be more robust against contaminants and process upsets resulting in an improved availability of the measurement. Since a refinery can have a large number of analyzers the reduced power consumption can lead to substantial power savings.
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