The third installment of our G908™ device series will look at the final oil & gas industry sector: downstream. (If you haven’t yet read our earlier blog posts on G908’s upstream and midstream applications, we encourage you to do so.)

In this post, we’ll discuss several G908 applications as they relate to processes in the downstream sector: accurately measuring BTEX compounds, monitoring natural gas composition and quantifying oxygenates during ethylene production.

Let’s take a deeper dive into these applications, and the role G908 plays in accurately characterizing specific components thereby ensuring product quality.

Measuring BTEX

Benzene, toluene, ethyl benzene, and the xylenes (BTEX) are volatile organic compounds commonly found in crude oil, gasoline, diesel fuel and other distillates. These chemicals are important intermediates in the manufacturing of paints, coatings, plastics, adhesives and rubber. However, BTEX compounds are also toxins of concern and this group is widely used as a marker of environmental contamination that can occur in many forms:  releases from underground storage tanks, accidental surface spillage during transportation and pipeline leaks. BTEX atmospheric contamination is due to vehicles and aircraft emissions as well as from combustion of organic materials. Exposure to these compounds can cause various health issues, ranging from skin irritation to cancers. These risks have prompted numerous regulatory bodies, including the EPA and many state-level health organizations to place heavy restrictions on permissible levels of these compounds.  Chromatographic BTEX analysis is widely used to determine these levels.

Traditionally, BTEX monitoring has to be performed in a lab, by chemists, using Gas Chromatography (GC) and GC-Mass Spec (MS) because these large, complex instruments are not designed for on-site deployment at chemical production facilities or remotely located suspected spill sites. We’ve addressed this with compact, robust design of G908.  Based on GC-HPMS (high-pressure mass spectrometry), G908 allows for easy deployment in the varied environments associated with BTEX testing.  G908 is capable of rapidly separating and accurately quantifying sub ppm levels of BTEX in seconds rather than minutes. What’s more, the simplicity of this device makes it possible for plant or field operators to run routine analyses themselves, without the need for specialized lab personnel.

Monitoring Natural Gas composition

Accurate, rapid quantitation of hydrocarbons and the various sulfur species occurring in natural gas are important for calculating the value and quality of gas being supplied to downstream facilities. Today, combining GC with a variety of detectors, such as, thermal conductivity (TDC), flame ionization (FID), pulsed flame photometric (PFPD) and sulfur chemiluminescence (SCD), is routinely used for natural gas analysis. However, the addition of GC-MS can significantly enhance the detection of even alkenes and sulfur species, which can be difficult to detect reproducibly with existing technology in complex hydrocarbon mixtures.  The transportable G908 contains a unique and powerful combination of dual resistively heated column modules, with integrated gas & liquid sample valves, FID, TCD and HPMS detection.  When coupled with JetStream, the devices operator-friendly control and data analysis package, G908 provides field and lab operators alike with a universal natural gas measurement tool that can be tailored for specific applications that include C1-C8+ for more accurate BTU & hydrocarbon dewpoint calculation as well as sulfur speciation.

Quantifying  Oxygenates during ethylene production

Worldwide ethylene production exceeds that of any other organic compound. Ethylene is produced from a variety of feedstocks including ethane, propane, butane, naptha & gas oil. Composition can vary greatly and these feedstocks must be tested for the presence of oxygenates, sulfur species and other contaminants. Accurate determination of sub ppm oxygenates, is challenging, as while extraction processes such as hydro-treating remove oxygenates, it is essential to monitor for traces of these compounds as they can degrade and inactivate expensive, high-yield catalysts commonly used for downstream polymer production. GC instruments with flame ionization detection remain the instrument of choice for determining oxygenates and have limits of detection around 100ppb. However, modern catalysts can start deteriorating when exposed to only low ppb levels and a more sensitive detection system, capable of correctly identifying and quantifying these compounds, is often needed. Laboratory GC-MS can identify and quantify oxygenates using total ion current (TIC) and selective ion monitoring (SIM), at detection levels well below those attained with GC, but has seen limited deployment due to high cost, size, complexity, the requirement for continuous high vacuum (0.0001 Torr) and associated maintenance needs to keep these systems operating 24/7 in production environments.

The G908 with its all-in-one Compact Core HPMS technology, modular column modules, integrated backflush valving and operator centric JetStream software, provides users with an ideal solution for routine online or at-line oxygenate analysis in ethylene production facilities. Being able to use SIM to measure specific oxygenate ions using their molecular ion masses, eliminates most of the interference often associated with FID or TIC traces, and provides oxygenate concentration results that are both accurate & precise.

These examples demonstrate that with the advanced and highly sensitive analytical capabilities of G908, operators can quickly and easily monitor BTEX, natural gas components and oxygenates present in a variety of matrices. The unique integration of ballistic GC separation technology with a selection of GC & GC-HPMS detection options enables the G908 to be deployed for specific downstream applications where conventional GC does not provide adequate performance, or standard GC-MS is simply too complicated for routine operation. By streamlining downstream analysis, as well as the procedures inherent in the upstream and midstream phases, G908 contributes towards reducing costs, time saving and resource optimization while ensuring product purity from the wellhead to the gas tank.

By Graham Shelver, Commercial Leader, Applied Markets