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Industrial support the natural production chain The contribution of industrial gases across the processing spectrum is crucial to performance and safety

STEPHEN HARRISON and ERNST MIKLOS Linde Gases

or decades, industrial gas salt-water corrosion could lead to a preheated. If this is not done, the companies have assisted rupture in one or more of the steel large, cold steel plates will lose heat Fproducers in the petrochemical components. Performance stand- too quickly and the will not landscape to ensure they are able to ards for exploration equipment be completely melted in the weld- deliver the levels of product quality components, particularly those ing zone, making a secure and operational safety demanded operating offshore, therefore connection impossible. Preheating by changing legislation, environ- confront manufacturers with tough will also prevent the build-up of mental regulations and customer challenges. cold cracks, which can occur due to requirements. As more high-strength steels are exposure or internal Industrial gases come into play being specified to manufacture stress in the component. from the very earliest upstream increasingly tough drilling equip- This is particularly important stage, where offshore exploration ment, this has resulted in an extra when treating high-strength steels. equipment is manufactured from preheating stage prior to After the weld, these materials steel and special metal alloys. These in order to safeguard the metallur- must be post-heated for around materials need to be cut, heated, gical properties of the steel. two to three hours to diffuse any welded and coated with the aid of Preheating prevents failures, such rogue hydrogen atoms in the weld industrial gases. In particular, as hydrogen-induced cracking, as seam. For manufacturers that have many applications associated with well as common failures in the to maintain a fast production drilling equipment now demand heat-affected zone. As more fine- speed, it is vital that they quickly the use of higher performance grained structural steels are being reach a preheated temperature of materials. These materials are a used to construct apparatus and greater than 100°C. world away from what was being equipment for the oil and gas In response, special burners for used as recently as 10 years ago , the importance of preheating steel before welding are and, as modern material specifica- preheating prior to the welding required. Linde has engineered a tions evolve, metal fabrication process is becoming a focal point. Lindoflamm burners for companies need to adapt their Welding in this application is a preheating steel before welding gases to suit the latest welding complicated affair. To begin with, takes place. Acetylene provides processes. the thick metal pieces need to be high heat intensity in the primary Offshore exploration equipment is often situated in some of the roughest and most inhospitable 2400 Acetylene seas, and has to be able to with- stand enormous loads from huge 2300 waves and swells and highly corro- 2200 sive conditions. High-quality steel and the most up-to-date production 2100 methods are necessary for explora- with ethene tion operations under such harsh Mixture with 2000 methyl acetylene conditions. In this context, welding Ethene becomes particularly important, as 1900 Flame temperature, ºC Flame temperature, the huge steel towers and support stilts are manufactured from many 1800 individual steel segments. A faulty 1:4 1:8 1:12 1:16 1:20 1:24 1:28 3 3 weld seam on a single component gas / air ratio, m /m can have catastrophic conse- quences. Cracks or dangerous Figure 1 Flame temperatures of gas/air

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is introduced into a 1.6 “tri-mix” with and nitro- gen, or as heliox, which is helium Acetylene mixed with low concentrations of 1.2 oxygen.

Mixture These mixtures are critical to the with ethene 0.8 well-being of the diver, as at these Mixture with depths and human blood Ethene methyl acetylene responds to gas in a different way. Propane 0.4 The mixtures must be certified safe Propene and need to avoid the presence of Methane dangerous chemical . The Flame propagation rate, m/s Flame propagation 0 gas process must be 1:4 1:8 1:12 1:16 1:20 1:24 1:28 absolutely precise and quality 3 3 / air ratio, m /m controlled to ensure that no oils, methane or infil- Figure 2 Flame propagation rates for hydrocarbon gas/air mixtures trate the mixtures. The effects of these substances are amplified at flame, establishing a focused flame, detects corrosion. Results show it depth and their inhalation could so that preheating occurs only in can improve the lifetime of heavy prove fatal. the weld area. This results in an exploration and processing equip- The human aspect of gas explora- increase in the speed at which the ment by up to 50%. This is a tion is coming to the fore as gas weld area is heated — as much as significant step forward in reducing companies are forced to go further two-thirds faster than that achieved the number of maintenance inter- afield to explore for by other fuel gases — plus signifi- vals required and the associated deposits, frequently in places where cant savings on total process cost. costs involved. the gas is difficult to extract. This As opposed to a propane gas A critical application of speciality means deeper exploratory dives flame, acetylene gas burns with a gases within the gas extraction and and oil rig maintenance at greater very precise, pointed “primary processing industry is the testing of depths. flame cone”, which drives the gas leakage detectors on offshore heat directly into the metal. drilling platforms. With tonnes of Extraction and processing

Additionally, flame temperatures natural gas being handled via the (N2) and

that can be reached with the associ- platform each day, any leakage (CO2) as bulk gases are used in ated acetylene- torch could build up rapidly into an huge quantities for the extraction — approximately 2400°C — are explosive atmosphere. Offshore and exploration of natural gas with significantly higher than those platforms, therefore, have perma- induced hydraulic fracturing, achievable using other fuel gases in nent monitors in operation, sniffing commonly known as fracking. The combination with air (see Figures 1 for gas seepage, and these gas traditional process for propagating and 2). detectors need continual testing trapped in under- Prolonging the lifespan of these and calibration with speciality gas ground fractures had required high offshore assets is another important mixtures. volumes of water, mixed with factor, since equipment lifespan foaming agents and friction reduc- impacts the price of the final prod- Human element ers and injected at high uct. This issue has led to the During the natural gas exploration into the fractures, cracking open development of special coating , a lot of the work takes place the shale and creating fissures, that lengthen the life- under the surface of the ocean, as allowing gas or oil contained time of offshore installations. Linde specialised technical divers under- within them to flow freely. Gases Division has recently devel- take oil and gas pipeline However, some of the issues that oped a state-of-the-art cathodic construction and maintenance, or have arisen over fracking have been protection as a first line maintenance of oil rigs and valves, linked to chemicals added to the of defence against metal corrosion. and so on. Underwater, these water to assist in the fracking Traditional arc spraying processes divers breathe a range of different process. These chemicals are involve the use of air to coat gases, depending on the depth at believed to have occasionally . However, the enhanced which they need to work. contaminated groundwater supplies, Linspray arc spraying process Recreational divers breathe air, with documented cases of seepage employs a mixture of nitrogen and but commercial divers plunging to into drinking water wells, often hydrogen to avoid oxidation of the depths of up to 50 m need special- through improperly sealed or aban- applied coating. The new technique ised mixtures of oxygen and doned drilling wells. There are also provides “active” protection, mean- nitrogen in varying concentrations. places where groundwater is only ing the coating materials will When divers are required to go several hundred feet above gas actively repair the surface as it down to between 50 and 200 m, reserves, where it is at risk of being

28 Gas 2013 www.eptq.com more easily impacted by fracking. ronment. It uses very few, or no, levels in the gas product are Conventional is chemicals and after fracking the controlled to less than 10 parts per often unable to remove the high nitrogen is released into the atmos- million. concentrations of salts and other phere, which already comprises For refiners, throughput of natu- toxic and biologically disruptive 78% nitrogen. Although relatively ral gas production can be limited compounds that can potentially be expensive in comparison to conven- by the speed at which plants can generated within wastewater from tional chemical fracking, it is being desulphurise natural gas. However, fracking — and if groundwater were used extensively for natural gas the more stringent the desulphuri- to become contaminated, it could extraction in areas of high environ- sation process becomes, increasing take years to clean an aquifer mental sensitivity. Claus plant loadings with hydro- system. Air or pure oxygen as an indus- gen sulphide and , the Alternative techniques that can trial gas is used for sweetening or more frequent bottlenecks in the help mitigate water-related issues removal of sulphur compounds production process also become. in fracking include employing CO2 from LNG and LPG process Claus plants operating in refineries mixed with alcohol or nitro- streams. This is often done by process concentrated hydrogen gen (LIN) in a process known as employing a process called Merox sulphide fractions, converting them dry fracking. The CO2/alcohol mix from UOP. The Merox process uses into elemental sulphur. The tech- is also injected at high pressure catalysts and caustic soda to extract nology is also able to destroy underground to open up fractures, low molecular weight mercaptans pollutants, particularly ammonia. with the CO2 expanding as it from the refinery gas stream. The Although not new, oxygen vaporises, allowing natural gas to mercaptide-rich solvent must then enrichment technology has now flow out through the cracks to be be injected with oxygen from come to the fore as a viable and collected and processed. compressed air or industrial pure cost-effective solution for signifi- is used for dry oxygen — for an enhanced regener- cantly increasing a plant’s sulphur fracking, a fracking process that has ation process — so that the handling capacity, as well as eliminated many of the problems mercaptides present are oxidised to addressing problems associated associated with hydrofracking and disulphides. The disulphides are with contaminants such as ammo- could prove to be more acceptable subsequently separated from the nia and hydrocarbons. Therefore, to people concerned about the envi- solvent so that typical mercaptan the use of oxygen debottlenecks the

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www.eptq.com Gas 2013 29 process and enables higher Accurate measurement embrittlement (LME), which weak- throughput and better returns on Industrial gases also play a major ens the original structure of steel, capital assets. role, helping to determine the aluminium and other metals in Oxygen enrichment of the British thermal unit (BTU) content process plants, is the main threat. combustion air significantly of natural gas, a measure of how LME is a form of cracking that increases sulphur handling capac- much energy will be liberated occurs when certain molten metals ity. Associated benefits include when the gas is burned. Speciality such as come into contact increased productivity achieved gases’ calibration standards are with structural alloys. The most without changing the pressure made with known BTU values to commonly affected materials drop, more effective treatment of measure LNG in the system, as this include carbon steel, low-alloy ammonia-containing feeds and less dictates how much the customer steels, high-strength steels, 300 effort required for tail gas purifica- will pay for a specific volume of Series stainless steel and various tion (reduced nitrogen flow). gas. alloys — nickel-based, copper, Oxygen enrichment is also a highly BTU values are very important aluminium and titanium. customisable approach to improv- when it comes to the transfer of LME introduces an acute risk to ing Claus plant yield, with options ownership of a natural gas stream an affected industrial plant. In a varying from low-level oxygen from one party to another. Natural worst-case scenario, structural fail- enrichment to employing advanced gas is a very mobile commodity ure could potentially result in a proprietary technology to bring and can be moved over long significant explosion in an oil refin- about capacity increases of up to distances, often across international ery or LNG facility, resulting in around 150%. borders. At the point where it catastrophic loss of life, excessive changes ownership or crosses damage to capital equipment and Transport borders, the calorific value must be long-term plant downtime. Once the natural gas has measured in an extremely accurate When natural gas is shipped into been located in the exploration way. These massive quantities of a port, samples are taken not only phase, it must be transported on gas are worth billions of dollars determine the BTU value, but also shore, either through natural gas and the billing must truthfully the mercury levels, which, again, liquefying stations or through reflect the energy value, consider- have a bearing on the function of pipelines. ing the high cost of error if the turbines used in the transport Depending on the corrosive calorific value is not precisely process. To support this measure- of the substance being trans- measured. ment, Linde produces a mercury ported, pipelines are generally Taxation authorities also base gas standard typically between manufactured from high-value their revenue on the value of the 1 and 60 µg/m3, which is the range fabrication materials such as product being distributed. The at which mercury exists in natural high-alloy or nickel-cladded steels. governments of countries involved gas. These are high investment materi- in this trade have specified that the als, and fabricators are sensitive to BTU measurement must be carried Emissions control, monitoring the need to work with them appro- out using high-quality, high- and analysis priately, and sophisticated accuracy, accredited gases, which Calibration gas standards are also industrial gases offer protection are traceable to international meas- widely used to monitor emission during the fabrication process. The urement standards. levels from gas processing or natu- smaller diameters and prefabricated It is also essential to measure the ral gas-fired power plants. With the steel pipes are joined using laser amount of mercury in natural gas. growing number of fracking opera- welding, and the bigger items are In oil and gas production and tions being initiated, natural gas is plasma or arc welded, all of them processing plants, the mercury becoming a more cost-effective protected from corrosion through present in natural gas poses a commodity, and an increasing the use of purging gas to prevent formidable threat to the safety of number of natural gas power plants deterioration. Gas purging is also humans and capital equipment, are coming online. Legislation environmentally friendly, allowing because of its propensity to amal- requires close monitoring of emis- for a reduction in the use of chemi- gamate with the materials of sions from these plants, focusing on cals to clean up an otherwise construction used for compressors the byproducts of the combustion oxidised weld. and high-speed rotating process, sulphur dioxide, carbon Where natural gas needs to be equipment. monoxide and nitric oxide. Where transported over long distances, For instance, if mercury should coal-fired power station emission usually by ship, liquefaction takes amalgamate to pump system concentrations are in the 50 to 100 place, using gases components or to the fins of turbine ppm range, natural gas has concen- such as , before the lique- blades, it could cause considerable trations around 10 ppm. However, fied natural gas (LNG) is pumped disruption by throwing these this model is also associated with into isocontainers or specially systems out of kilter, and therefore emissions such as ammonia and designed storage vessels on the potentially cause immense struc- , both of which are ship. tural damage. Liquid metal considered greenhouse gases, and

30 Gas 2013 www.eptq.com measurement of these compounds gases. Industrial gases will there- career in industrial gases spanning 20 years, he is enabled with high-precision fore play a progressively critical holds a master’s in chemical from speciality gas mixtures. role across the entire value chain, Imperial College, London. When it comes to natural gas helping to ensure that all phases of Ernst Miklos is Head of Segments Management, combustion control in power gener- the process operate effectively and Manufacturing Industries, Linde Gases Division. He has 22 years’ experience in welding ation, plant operators need accurate safely, and that environmental technology R&D and market development, and information about the combustion impact is minimised. heads a global team of engineers focused on gases in the system. To avoid over- gas technologies to serve energy infrastructure. feeding or underfeeding natural Stephen Harrison is Global Head of Specialty He has a degree in mechanical engineering gas into the system, operators rely Gases & Specialty Equipment with Linde Gases. He has worked in an international capacity for from the Polytechnic Institute Timisoara, on BTU values to provide insight both Linde Gases and previously BOC, and now Romania, and is a certified European Welding and it is therefore imperative to leads Linde’s Global Specialty Gases & Specialty Engineer and a Member of the Research Board have highly accurate calibration Equipment business from Munich, Germany. A of the German Welding Society (DVS) and TWI, gases made with those specified British Chartered Engineer (MIChemE) with a among others. BTU values in order to monitor the combustion gases and help main- tain control throughout the process. Inside the combustion chamber, it is also necessary to monitor oxygen levels to support fuel and carbon dioxide levels, to control the combustion process and minimise greenhouse gas emissions. These measurements also require special- ity gases calibration mixtures to support the instrumentation. Effective monitoring of combustion and optimisation of the process is the key element of emissions reduction. High-purity “zero” gases are used to zero out the analytical instruments that monitor the output of flue gases from natural gas processing plants. Accurate and pure zero gases are a critical element of monitoring, because any trace amounts of impurities can alter or skew results. An increasing number of mole- We Process Your Energy cules is being analysed and measured to support the growing TECHNOlOGIES aND EquIPmENT FOR OIl & GaS TREaTmENT trade in emissions from natural gas YOuR EFFICIENCY, OuR FlExIBIlTY combustion. In the US, there is a strong drive to monitor all the Because Oil & Gas projects require highly reliable and cost effective solutions we timely deliver since over 35 years fully guaranteed modular process- greenhouse gases being emitted equipment packages tailored to meet specific customer’s requirements; for from a process, and this trend is all kind of Oil & Gas processing applications. likely to go worldwide, bringing Because each project is unique and highest quality design is paramount to under the spotlight emissions of success we offer a unique portfolio of proprietary gas treatment technologies licensed by Prosernat. Backed by our strong investment and partnerships gases such as nitrous oxide, in R&D, with IFP Energies nouvelles and Total, we are proud to bring to ammonia, , the market the most advanced technologies in the following areas: Natural formaldehyde, sulphur hexachlo- Gas Sweetening, Natural Gas Dehydration, Sulfur Recovery, Hydrocarbon Dewpointing, Separation and CO Capture from Flue Gases. ride and carbon dioxide. 2

The future As the oil and gas industry advances, the more complex the processing of natural gas will become. This maturing value chain is going to demand increasingly high-quality and sophisticated

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