Measurement and Testing
23
Statement Kuraray: “By using the additional GCs as control element, improved process stability, distillate qualities and energy consumption have been the major outcome of this project!
Picture 3: System integration: Analyzer house with 2 process GCs - Optimized for best reliability using liquid sample streams
© AGT-PSG 2022, All rights reserved
Process GCs optimize the distillation process of the Kuraray polyvinyl alcohol plant in Frankfurt
The following use case addresses the specifi cs of integrating a process analyzer system into a chemical production plant. Due to the high fl exibility of application usage of a process GC, the design, the plan, and the manufacturing of a sample preparation system is a key for a proper GC operation.
In terms of the possibility to measure different sample streams with just one process GC, the different samples often need to overcome large distances from the tapping point to the fi nal installation of the GC. For this reason, it is crucial to build up a fast loop system, that considers T90 time, the pressure and temperature levels at the sample tapping and the sample return point to secure an appropriate and fast fl ow of the sample over the fast loop. This is necessary to secure that the sample itself is actual and representative when it is injected to the GC.
Next to the fast and reliable transport (considering also back- purge possibilities and barriers) of the sample, transporting just a small and needed amount of sample to the GC is also crucial. It is often mandatory to decrease the fl ow to the injection valve because you do not want to have that big amount of gas going over the valve to the atmosphere, or - when we talk about liquid injection - not that big amount of liquid sample going to the slop. In the described use case, it is possible to integrate the sample which is going over Liquid injection Valves for high and low boiling components, directly to the fastloop system with an intelligent fl ow-controlled sample preparation system. The complete sample is with this solution 100% recovered and there is no waste of sample and energy.
Industrial samples are often complex, fl ammable, explosive and/or they tend to polymerization. Considering health, fi re and explosion issues, a fast loop system is often installed directly in the fi eld, so that the high amount of sample stays in the fi eld, and that just the necessary amount of sample is going to the analyzer room and to the GC. By consindering an appropriate air exchange concept with integrated fl ow monitoring and additional safety measures like monitoring potential leakages with LEL (Lower Explosive Limit) and toxic gas (Tox) sensors and using a Sample Shut off valve as safety valve for the analyzer room the solution provider AGT-PSG has realized a fast, safe, and reliable installation to secure a perfect operation of the process GC.
In regard to the use case a good and real partnership between the process experts from the operator Kuraray, the GC experts from Siemens, and the system integration experts from AGT-PSG was essential for the successful implementation of the GC project. While Kuraray identifi es the optimal sampling and return points,
Author Contact Details Harald Mahler, Business Development Professional Siemens AG • Oestliche Rheinbrueckenstr. 50 D-76187, Karlsruhe, Federal Republic of Germany • Email:
contact@siemens.com • Web:
siemens.com/process-analytics
Thorsten Reisinger, Managing Director AGT-PSG GmbH & Co. KG • Weißkirchener Str. 3 D-61449, Steinbach, Federal Republic of Germany • Email:
t.reisinger@
agt-psg.de
Harald Mahler Thorsten Reisinger
Picture 4: Sampling system design variants for liquid samples – heated in cabinet (right) and unheated on SS plates (left)
© AGT-PSG 2022, All rights reserved
and also specifying the real need of what to measure, a feasibility study with the Siemens MAXUM Ed. II process GC gave conviction that the use of airless GCs gave stable values and also that the needed accuracy was reached. With the design, the layout and the installation of the complete analyzer arrangement, AGT-PSG delivered an appropriate sample conditioning system, equipped the complete analyzer room and installed the MAXUM Ed. II process GC to secure a precise measurement. By enjoying this excellent collaboration, the Kuraray production plant was able to reach a next level of effi ciency.
Why is custody transfer important? TALKING POINT
Oil and gas is a global industry, with high-value resources often exchanging hands multiple times and crossing several international borders before reaching a fi nal destination. Examples include railcars transporting Athabasca oil sands crude to American refi neries, cargo ships transporting Saudi Arabian oil to China and pipelines transporting Norwegian gas to the UK via the North Sea. Below, we spotlight some of the key goals of custody transfer for oil and gas applications.
• Maximising accuracy
Accuracy is the principal goal of custody transfer processes, with state-of-the-art technology used to measure fl ow rates with granular precision. For high-value commodities such as WTI and natural gas, even the smallest measurement errors can result in signifi cant losses (or gains) when ownership is transferred. For example, LNG shipment values often exceed £30 million. While a 1% error in Gross Calorifi c Value (GCV) as LNG is transferred from the dock to cryogenic tanks onboard a ship may seem small, it can equate to signifi cant losses for the short changed party. Custody transfer metering systems for LNG include ultrasonic or Coriolis cryogenic fl ow meters.
• Protecting profi ts
At crude oil pumping sites, a Lease Automatic Custody Transfer (LACT) unit may be used to measure net volume as crude is transferred from a storage tank to a pipeline. With the EIA predicting the price of Brent crude will slump in 2022 and 2023, protecting profi t margins is a top priority for producers and buyers.
• Meeting industry and government standards The oil and gas industry is heavily regulated to protect the interests of both buyers and sellers. Many countries enforce their own local laws in addition to regulations published by bodies such as the International Group of Liquefi ed Natural Gas Importers (GIIGNL) and the International Organisation for Standardisation (ISO).
Implementing custody transfer systems A good custody transfer system doesn’t rely exclusively on an accurate metering system. As well as fl owmeters, a foolproof custody transfer system should include the following components: • Advanced computers and software to analyse fl ow rates, process data and detect errors. All fi eld data should be analysed by the fl ow computer, which generates reports and
ensures both parties meet the requirements of the contract.
• Integrated quality and sampling systems, such as gas chromatographs, to monitor the characteristics of the commodity being transferred.
• Calibration instruments, such a provers, to regulate fl ow meters before, during and after a custody transfer transaction takes place.
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