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Detecting sulphur in hydrocarbons

1st April 2013


Page 1 of 2

The petroleum industry relies on high-speed, accurate and regulation-compliant measurement of sulphur content to maintain productivity. Sean Ottewell reports.

n a sign of the on-going importance of sulphur analysis technology, XOS has installed its 1000th SINDIE 7039 sulphur analyser. The recipient is the Yanshan refinery of the China Petroleum & Chemical Corporation (Sinopec).

The announcement builds on XOS's steady growth in the energy sector. "From the time that we launched production of the first-generation SINDIE analyser to the shipment of this 1000th unit, the SINDIE product line has earned a reputation as an indispensable analytical instrument for today's energy companies," said Berry Beumer, vice president of sales and marketing at the company.

"This latest milestone affirms XOS's commitment to leading-edge technology solutions that address analytical challenges which support the success and productivity of the global energy sector," he added.

The energy sector demands state-of-the-art detection performance, reliability, and ease-of-use from its materials analysis tools, and SINDIE analysers help XOS's customers monitor sulphur content in such diverse fuels as crude, biofuels, gasoline, and ultra-low sulphur diesel (ULSD) with what the company describes as unrivalled accuracy.

SINDIE offers many advantages with a measurement technique based on monochromatic wavelength dispersive X-ray fluorescence (MWDXRF). The practical application of this technology in the SINDIE product line enables energy and transportation companies to meet clean-air mandates enforced by global regulators.

In turn, this reduces sulphur-oxide exhaust emissions that are responsible for producing acid rain and causing adverse health and environmental conditions.

Sinopec received recognition of this milestone at its refinery in Yanshan, China.

According to a Sinopec executive, "The analyser has demonstrated significant performance advantages over other commonly used methods, such as coulometry, UV fluorescence, and conventional X-ray fluorescence. These advantages include high detection precision, high analysis speed, ease-of-use, high stability, and low maintenance. The analyser has received wide acclaim from operators and technical staff during the course of operation. In particular, the refinery division of the Sinopec Yanhua Company recently received high-octane fuel components, which required high-analysis precision and speed."

The SINDIE product line serves diverse market segments such as petroleum production, refining, and distribution; petrochemicals; biofuels; enforcement; independent testing; and power generation.

End-users include refinery labs, pipeline and marine terminal operators, enforcement authorities, and third-party test labs.

XOS spearheaded the ASTM D-7039 standard development covering the SINDIE measurement method, and the company maintains the task group chair for measuring sulphur in fuels.

Regulators worldwide recognised D-7039 for the purpose of certifying sulphur in fuels.

A portable version of the SINDIE benchtop analyser -SINDIE On-the-Go (OTG) - received Instrument Business Outlook's 2009 Industrial Design Award for portable instruments.

Microprocessor-driven

Meanwhile, with over 25 years of experience in developing and manufacturing sulphur analysers and associated parts and supplies, Analytical Systems International (ASI) has met these requirements with its proven microprocessor-based analyser.

The Model 1700 system measures total sulphur by hydrogenation similar to that as described in ASTM method D3031, D4084-82, D4468-85 and 4045-81. The sulphur sample is precisely metered into a continuous flowing stream of hydrogen gas. The sample and hydrogen are heated in the furnace up to 1315°C resulting in thermal cracking of the sulphur and the formation of H2S.

After complete humidification of the sample, the H2S comes in direct contact with the lead acetate tape and produces a darkening of lead sulphide that is immediately measured by the photodiode/LED optics and rate-of-reaction digital electronics to provide an accurate and reproducible total sulphur analysis with ppb or ppm sensitivity up to 100 per cent. The LCD display provides the current reading, any alarm condition, procedure prompts (such as calibration procedure), and failure indicators (local and remote capability). Quality materials are selected for their compatibility and utilised through fabrication. Special attention is given to wetted parts that come in contact with the process stream and are selected to be non-reactive with H2S.

The company cites four important applications:

- Alkylation. The alkylation processes used in production of high octane, low leaded gasolines can result in the formation of acid soluble oils due to excess sulphur content in the feed stock. This results in decreased profits. Utilising a continuous on-line sulphur analyser can help avoid these losses.

- Sulphur in ammonia. Sulphur compounds such as hydrogen sulphide, mercaptans, and carbonyl sulphide can react with catalytic metals and form useless oxides. A two-year catalyst bed could well be destroyed in a few hours resulting in losses of over a million dollars. The continuous on-line total sulphur analyser can prevent this disaster.

- Reformers. Reformate catalysts are especially susceptible to sulphur poisoning. The newer transition metal catalysts are even more susceptible to sulphur poisoning. Grab samples sent to the lab for analysis cannot be analysed often enough to provide adequate protection. The continuous on-line total sulphur analyser provides fast, accurate information to protect the catalyst.

- Sulphur in synthesis gas. Many synthetic gas feed stocks contain excessive sulphur levels. These are normally hydrodesulphurised down to 100 ppb or less. Theoretically, if 100 per cent conversion is achieved, the remaining sulphur compound is hydrogen sulphide. Depending on the efficiency of the hydrodesulphurisation process other sulphur compounds such as carbon disulphide, carbonyl sulphide, and thiophenes could be present. These sulphurs could result in catalyst life being reduced to hours instead of years. The continuous on-line total sulphur analyser can provide analysis for monitoring catalyst, says ASI.

For its part, Thermo Fisher Scientific has launched a new total nitrogen and total sulphur (TN/TS) analyser, which features an innovative direct injection design providing the capacity to analyse both heavy and light hydrocarbons without changing introduction modules.

As a result of the versatility, precision and accuracy offered by the Thermo Scientific iPRO.

5000 series analyser, scientists in petrochemical and commercial testing laboratories, oil refineries, R&D centres and chemical plants, will benefit from significant time savings and productivity advantages, in addition to total ASTM compliance (Fig.1).

The iPRO 5000 series TN/TS analyser features the proprietary Thermo Scientific jetPRO direct spray injector, which enables automatic analysis from ppb levels up to percent levels for both nitrogen and sulphur on just one instrument and without changing introduction modules. As a result, it is now possible to quantify nitrogen and sulphur in heavy hydrocarbons within just three minutes.

Compared with the standard boat method, this is a dramatic reduction in the time spent from analysis to viewing results, which provides an immediate cost-saving and productivity increase.

Offering exceptional precision of two percent or better when analysing light hydrocarbons at ultra-low concentrations, the analyser ensures high accuracy, as well as reproducibility and repeatability of analysis. Providing meticulously controlled combustion processes, the analyser also contains a proprietary pre-soot detection technology which ensures complete combustion that is soot-free.

Thermo Scientific says that the iPRO 5000 series analyser is also the smallest and most compact total nitrogen and total sulphur analyser currently available.

Developed for a wide range of applications, the iPRO 5000 series analyser offers an ideal solution for the diverse requirements of petrochemical analyses.

The instrument provides the capacity to analyse virtually any refinery sample from raw crude to end product, while ensuring ASTM compliance and enabling optimisation of refinery processes. For commercial testing laboratories requiring ASTM compliant results quickly and cost-effectively over a wide range of applications, the iPRO 5000 series analyser is four times faster than previous methods which enables a significant increase in productivity and cost-efficiency.

In addition, the instrument's exceptional precision makes it the ideal choice for high performance applications such as those conducted by R&D centres.

The iPRO 5000 series analyser is controlled by Thermo Scientific NSX Visual software, which supports Microsoft Windows 7 and has been developed to adapt to the specific workflows of users who require ease-of-use and flexibility.

The NSX Visual software assures total ASTM compliance through pre-loaded ASTM method templates, which enable the user to simply select the required method and start the analysis. The software is also programmed to proactively alert the user if method parameters are changed to a value which is outside the scope of the official ASTM methods.


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