Odor Management in Refinery Operations –Where odor occurs and how it is managed. 

What are Mercaptans and where are they found? 

Methyl mercaptan, or methanethiol, is a colorless, flammable gas that smells like rotten eggs and is present in many different ways in our environment. For example, onions, asparagus, oranges, and radishes are some foods that naturally contain mercaptans. Certain marine bacteria can also generate mercaptans, they are partly responsible for the marshy or stagnant smell in water. Due to its distinct smell, mercaptans can be helpful odorants to aid people in detecting the presence of other gases or chemicals since they can be noticed by humans in lower quantities. This is why mercaptans are added in low concentrations to natural gas.  

Although commercially added mercaptans are helpful, naturally occurring mercaptans form in much higher concentrations and their presence may cause corrosion to production sites, health issues to personnel, and noxious discomfort to workers and communities that live close to where these afflicted hydrocarbons are processed, which includes crude oil and refined products. Because of these issues, there are oilfield chemical companies that provide odor control chemicals that not only eliminate the rotten -egg smell but also help with all mercaptans’ inconveniences.

In this blog, we will dive into how to deal with naturally occurring mercaptans and mercaptan odor control. 

Why we need to treat Mercaptans. 

Mercaptan odor control is one of the many aspects addressed when dealing with mercaptans. Aside from odor issues, mercaptans increase corrosivity, contribute to instability, and make it exceedingly difficult to meet product specifications. The presence of mercaptans along the oil production chain can create problems both from steel and alloys corrosion during storage and transportation, to odor complaints from neighbors.

This is why mercaptan removal is necessary in feedstocks and refined products.  

While mercaptans are closely related to hydrogen sulfide (H2S) and may be efficiently handled with comparable methods, there are certain unique issues to be aware of: 

1. Detection levels for mercaptans are much lower than hydrogen sulfide, so it is way easier for mercaptans to cause complaints. 
2. Mercaptans are not as soluble in water as H2S. Water solubility is an important property of chemicals because it impacts how easily they will break down. 
3. Mercaptan molecule structures have a higher level of complexity than H2S molecules. Since mercaptans undergo additional steps in their biological breakdown, treating them may take longer. 
4. Although noxious at moderate levels, even high mercaptan levels are not fatal as compared to relatively low levels of hydrogen sulfide (H2S). 
5. Mercaptan molecules are more complex than H2S and are harder to break down. The simplest mercaptan is methyl mercaptan but chained/complex mercaptans are also common. 

How to manage Mercaptans 

Our mercaptan scavenger, ProM®, is currently being used in multiple applications to reduce the presence of mercaptans. ProM® has consistently outperformed alternative chemistries for lower chain mercaptan removal. 

How ProM® works at a glance: 

1. First, a specialized lab analysis is made to determine the mercaptan levels and variety of mercaptan species present. 
2. Based on lab results, we determine the appropriate dosing of ProM® chemical. 
3. Introducing the product to the afflicted crude oil or liquids at a point in the pipeline or vessel that has the most effective turbulence and contact time is critical.  
4. Lastly, a repeat test confirms that quality spec has been reached and the volume may continue to sales. 

Remember, unlike H2S, mercaptans are overly complex branched sulfur-based hydrocarbon chains that require lab analysis to determine treatment approach. ProM® has been specifically engineered to use non-triazine/non-amine based chemicals, which makes it safe to be used in refineries. 

Conclusion 

When mercaptans are treated, crude oil commercial specs are achieved, and the crude may be sent to a refiner. Additionally, odor is controlled and neighborhoods downwind from the facilities will not be affected. And finally, the health and safety of the workers on locations is improved. 

Whether you need mercaptan removal from natural gas, wastewater odor control, mercaptan removal from LPG, or from any other hydrocarbon, contact us to find solutions to mercaptan contamination. We have the mercaptan scavengers to satisfy your needs and we offer many more oilfield services for H2S and mercaptan treatment.

Sources: 

https://www.chemicalsafetyfacts.org/chemicals/methyl-mercaptan/#:~:text=Methyl%20mercaptan%2C%20or%20methanethiol%2C%20is,from%20paper%20and%20pulp%20mills. 

https://chem.libretexts.org/Courses/Northeastern_University/12%3A_Chromatographic_and_Electrophoretic_Methods/12.4%3A_Gas_Chromatography 

Quality control is the basis for our business. Delivering high-quality products is fundamental to our clients. Providing consistent, high-quality products time and time again leads to long-term and trusted partnerships.

Therefore, keeping a close watch and testing our batches ensures our manufacturing processes are not deviating and we deliver the highest quality possible.

In much the same way, when out in the field, we are often asked to check unknown products. This arises at the request of the client if their existing product is not effective or worse, causing production hindrance.  This is performed as a troubleshooting effort for our clients and is the starting point in discovering a workable solution.

So how do we ensure in the lab that our manufactured products are meeting our exacting standards or how we determine what an unknown field substance may contain? One of the many advanced ways we detect the presence of different ratios of chemistries is by utilizing a Fourier-transform infrared spectroscopy (FTIR) unit. 

Maintaining the highest quality of our chemical products is fundamental to how Q2 Technologies ensures we maintain our trusted partnership status for leading Oil & Gas producers, midstreamers, refiners, biogas, and wastewater operators. We rely on proven technologies not only for our chemical products, but how we implement them in our growing range of industries. 

Not Just in the Name

For over 20 years, Q2 Technologies has been at the forefront of chemical development and implementation in Oil & Gas, and as such, ‘technologies’ is a core concept we embrace from early stage chemical development, to the logistics of manufacturing, to final implementation for the end-user. Our clients know that we scrutinize all aspects of our process and it shows in the results of having consistent products at or near the clients’ locations every day of the year. Check out our latest inventory initiative announcement here [insert link to recent mid-season hurricane and inventory PR announcement]. 

One of the more advanced techniques we utilize to ensure our unique products are manufactured to our tight specifications and standards is the use of infrared (IR) spectroscopy. IR spectroscopy, specifically Fourier transform infrared (FTIR) spectroscopy, is a widely popular analysis technique used today. FTIR is used across many industries as the process is quite adaptable to suit many scenarios. Considering that it has use cases for all types of matter: solid, liquid, and gaseous analytes. 

How it works

The study of infrared light dates back to the astronomer William Herschel in the early 19th century. Herschel used a prism to refract light from the sun and noticed the temperature increase when focused beyond the red portion of the spectrum. Although the term infrared was not used until the late 19th century, beyond the visible red light was surely a curiosity to him. Since then, the study of the interaction of IR light with matter has expanded greatly. In the ongoing studies with a FTIR device, a light source shines on a substance and the resulting wavenumber or unique IR signature is observed on a detection plate. The study of chemical bonds has proven that molecules are not held together in static fashion, rather they vibrate at the molecular level leading to concepts of symmetrical and asymmetrical stretching, wagging, scissoring, rocking, just to name a few, and when IR light attempts to pass through certain molecules that are vibrating at different frequencies, we can determine with high confidence that a particular molecule is present. The process yields a detection graph that will have a series of unique identifiers that would confidently point to different chemicals present. 

The FTIR test would be akin to a baker identifying all of the ingredients of a cake, to replicate the recipe, one would need the measurements of each ingredient. That is where we pause in our evaluation of unknown substances, chiefly we do not need to recreate a substance and secondarily, this is where the science and artform deviate, beyond the FTIR test, one is making gross assumptions. However for our purposes, the resulting identification of the presence of certain elements is quite sufficient, with this information we are able to make inferred rational judgements on the nature of a product. Again this works well for our quality control best practices, for example if a significant presence of an out of place molecule shows, we may with statistical evaluation conclude that the sample has been contaminated and would need to be reconfigured. To be fair, significant deviations are taken into account, as well as a deep understanding of how our product would chemically react to the rogue molecules.

Putting it into Practice

As part of our professional service offerings of supplying chemical products to our clients’ different facilities, we take a concerted effort to ensure that the products are delivered on time to location and are administered appropriately. Word can travel fast in the oil patch and this can lead to potential clients requesting us to troubleshoot why their chemical products are not as effective or at worse causing production curtailment, in short, they are seeking to know what is causing the issue. We start by reviewing the SDS and comparing that to what the FTIR analysis provides. In some cases, products are diluted or manufactured with other chemicals, rendering them less effective. Oftentimes, a solution for H2S or mercaptan treatment from our ProSeries® suite of products is a good fit and we are able to quickly scope out a workable application. 

If you would like to learn more about how we use FTIR analysis in the lab or how it may apply to your asset in the field for hydrocarbons afflicted with H2S or mercaptans, we would be happy to discuss with you your situation to find solutions. Contact us today!

Sources:

https://www.technologynetworks.com/analysis/articles/ir-spectroscopy-and-ftir-spectroscopy-how-an-ftir-spectrometer-works-and-ftir-analysis-363938

https://www.advancedmicroanalytical.com/AMAServices.aspx?mode=tech&id=15

https://www.advancedmicroanalytical.com/AMAServices.aspx?mode=serv&ID=2&bcl=2&device=c&network=g&keyword=ftir%20testing&matchtype=p&creative=315579260549&gclid=Cj0KCQjwpeaYBhDXARIsAEzItbETDIFmls2Tb28E1uxm3rJ-6uKnSAETsPCFo9m30Z7_KFsl08oQDAMaAvB1EALw_wcB

FTIR Image Source:

https://calce.umd.edu/fourier-transform-infrared-spectroscopy

When choosing the appropriate H2S Scavenger either for oil treatment, acid gas sweetening, mercaptan odor removal or through mechanical processes, it is essential to fully analyze the different alternatives on the market, as different products are better suited for different applications and process conditions. As our analysis will show, one may be better than the other depending on the specific conditions of what needs to be treated. Over the years, triazine-based treatment has been the go-to solution for many Producers, Midstreamers, and Refiners, and to a large extent it is still the go-to choice. But for some, implementing new technology such as non-triazine products has positively impacted their operations and has lowered their costs. Is one better than the other? That all depends on your use case and process conditions. Here you’ll find a brief description of both triazine and non-triazine alternatives to help inform you of the effective solutions on the market for your application.

Triazine Treatment

Triazine for H2S scavenging is an established and reliable chemical reaction that is employed in the Oil & Gas industry to remove H2S from gas streams. The H2S scavenging can be done via direct injection in pipelines with fog nozzles, wet scrubbers, or bubble towers at either wells, central batteries or midstream systems. The triazine scavenging technique is most cost-effective for gaseous streams with sulfur loading of less than 1000 lbs. per day. It typically reduces H2S concentrations to <4 ppm and partially removes several light mercaptans (methyl, ethyl, and propyl). Triazine’s ability to remove H2S is affected by various parameters, including temperature, pH, contact duration, and natural gas composition. The final product is water soluble and is usually discharged in the produced water tanks and commercial saltwater disposal facilities. 

It is important to note that using triazine as an H2S scavenger may cause fouling from the polymerization of dithiazine in contact towers, scrubbers and/or pipelines. Careful use and monitoring of the triazine solution is needed to ensure smooth operation. Q2 Technologies has been manufacturing traditional triazine blends for decades and also offers expertise in developing unique formulas for special cases. 

Check out this case study:

Non-Triazine Treatment

Even though triazine is a well-trusted solution, many companies have chosen non-triazine-based scavengers as alternatives for use in crude oil applications. One of the main characteristics of our non-triazine product, Pro3®, is a non-amine and non-glyoxal technology, making it safe for refineries and pipelines. If left unchecked, Amine salts that form from spent triazine can ultimately cause damage to the top stacks of a refinery when heated to >500 °F. Many refiners in the US Gulf Coast and overseas monitor amine content and require traders and midstream companies to use vetted non-triazine chemistries. 

Producers and Midstream companies alike have found success with our non-triazine products: 

• The quality of the oil is upgraded when H2S content is reduced. 
• Safer environment for all personnel on-site.
• Infrastructure and equipment will last longer now that corrosion caused by H2S has been neutralized. 
• Our non-triazine scavengers are not based on commodity-priced products, so our prices are protected and are less impacted by external factors such as freezes and industrial raw material shortages.

Our non-triazine H2S removal technology has proven to reduce chemical use up to 50-75% as compared to triazine. This definitely does not mean that triazine should always be replaced by non-triazine, rather, Q2 Technologies can assist you from a technical, engineering, and commercial viewpoint. Each application is different and needs to be carefully analyzed to determine the treatment product. 

In conclusion, both triazine and non-triazine scavengers have their benefits and are the go-to alternatives for oil and gas treatment. But, one may be better than the other depending on the specific characteristics of the product that needs to be treated. If you’re looking for the right H2S scavenger solution for your company, feel free to contact us! 

Sources:

https://www.sciencedirect.com/science/article/abs/pii/S1875510017304559