Natural Gas Processing And Dew Point Control. Gas separated in this unit is sent to acid gas recovery; the condensate or the oil recovered is usually sent to a refinery for processing, while water is disposed, or treated as wastewater. A generalized natural gas flow diagram is shown in Figure 12.2 [7]. Once NGLs have been removed from the natural gas stream, they must be broken down into their base components to be useful. Author: Dr. Semih Eser, Professor of Energy and Geo-Environmental Engineering, College of Earth and Mineral Sciences, Penn State. Following the NGL extraction, the treated natural gas stream that is, now, mostly methane, or a gas compliant with the natural gas specifications is sent to the pipeline for transmission to the point of use. While the ethane, propane, butane, and pentanes must be removed from natural gas, this does not mean that they are all ‘waste products’. Natural Gas Processing; We offer reliable solutions across the natural gas value chain through a broad technology portfolio that includes gas conditioning and treating, fractionation, deep ethane extraction and LPG recovery, and liquid product treating. Most often, however, the gas contains unacceptable levels of higher-weight hydrocarbon liquids as well as impurities, and it is available only at very low pressures. This is a precursor to LPG gas manufacturing process (LPG production process). Cryogenic processes are also used to extract NGLs from natural gas. Butane Splitter or Deisobutanizer - separates iso and n-butanes. Note that the fractionation unit may also include a butane splitter or deisobutanizer to separate n-butane and iso-butane. The ‘rich’ absorption oil, now containing NGLs, exits the absorption tower through the bottom. These types of dehydration systems are best suited for large volumes of gas under very high pressure, and are thus usually located on a pipeline downstream of a compressor station. These NGLs are sold separately and have a variety of different uses; including enhancing oil recovery in oil wells, providing raw materials for oil refineries or petrochemical plants, and as sources of energy. Once the natural gas has been fully processed, and is ready to be consumed, it must be transported from those areas that produce natural gas, to those areas that require it. In general, natural gas processing includes the following steps: In addition to these processes, it is often necessary to install scrubbers and heaters at or near the wellhead. Major transportation pipelines usually impose restrictions on the make-up of the natural gas that is allowed into the pipeline. These plants are located on major pipeline systems. The behavior of natural gas, whether pure methane or a mixture of volatile hydrocarbons and the nonhydrocarbons nitrogen, carbon dioxide, and hydrogen sulfide, must be understood by the engineer who is designing the operating equipment for its production, processing, and transportation. PETROGAS has been a recognized leader since 1975 in the design, manufacturing, and operation of gas … In most instances, natural gas liquids (NGLs) have a higher value as separate products, and it is thus economical to remove them from the gas stream. Source: Duke Energy Gas Transmission Canada. There are two basic steps to the treatment of natural gas liquids in the natural gas stream. Fractionation works based on the different boiling points of the different hydrocarbons in the NGL stream. In addition to the four processes above, heaters and scrubbers are installed, usually at or near the wellhead. Thanks to the recent shale boom in North America, natural gas is … - Selection from Natural Gas Processing [Book] By merging Axens Solutions’ products portfolio with Prosernat gas treatment technologies portfolio, Axens Solutions possesses all the treatment, purification and drying technologies necessary for the production of purified natural gas that meets the specifications for natural gas … When sour gas (i.e., gas containing H2S) is compressed, the compressor discharge gas is used as a seal gas that is routed to the inlet of the first stage of the compressor. There are a number of different ways of chilling the gas to these temperatures, but one of the most effective is known as the turbo expander process. Natural gas, as it is used by consumers, is much different from the natural gas that is brought from underground up to the wellhead. Although the natural gas that arrives at these straddle extraction plants is already of pipeline quality, in certain instances there still exist small quantities of NGLs, which are extracted at the straddle plants. This stage is called Gas Treatment. Although the processing of natural gas is in many respects less complicated than the processing and refining of crude oil, it is equally as necessary before its use by end users. The particular fractionators are used in the following order: By proceeding from the lightest hydrocarbons to the heaviest, it is possible to separate the different NGLs reasonably easily. As the natural gas is passed through an absorption tower, it is brought into contact with the absorption oil which soaks up a high proportion of the NGLs. Today approximately 30% of the world's energy demand is derived from natural gas. The sour gas is run through a tower, which contains the amine solution. This absorbing oil has an ‘affinity’ for NGLs in much the same manner as glycol has an affinity for water. The extracted natural gas is transported to these processing plants through a network of gathering pipelines, small-diameter, low pressure lines. This rapid expansion of the gas allows for the lowering of the temperature in the separator. "This natural gas processing book would be an excellent addition to the reference collection of large academic libraries at universities with programs in oil and gas area. For the Qatar region, natural gas processing is of crucial importance. Most produced gas must be treated before the consumer can use it, and there were nearly 2,000 gas processing plants operating around the world as of mid-2006. Riazi, S. Eser, J. L. Peña Díez, and S. S. Agrawal, “Introduction” In Petroleum Refining and Natural Gas Processing, Editors: M. R. Riazi, S. Eser, J. L. Peña, S. S. Agrawal, ASTM International, West Conshohocken, PA, 2013, p.12. New in Gas Processing Technology-Adrienne Blume, October 01, 2020 Hydrogen & syngas plants. Natural gas processing consists of separating first, all impurities found including acid gases, water vapor, and inert gases. Should these hydrates accumulate, they can impede the passage of natural gas through valves and gathering systems. Sour gas is undesirable because the sulfur compounds it contains can be extremely harmful, even lethal, to breathe. In all, the Claus process is usually able to recover 97 percent of the sulfur that has been removed from the natural gas stream. Absorption occurs when the water vapor is taken out by a dehydrating agent. Natural gas hydrates are crystalline ice-like solids or semi-solids that can impede the passage of natural gas through valves and pipes. ]A. J. Kidnay and W. R. Parrish, Fundamentals of Natural Gas Processing, CRC Press, Boca Raton, FL, 2006, p.16. The site editor may also be contacted with questions or comments about this Open Educational Resource. [7.] Natural Gas Processing. Once the gas stream has had the acid gases and water vapor removed, it is now classified as dry, sweet gas, and is suitable for even further processing. Solid-desiccant dehydration is the primary form of dehydrating natural gas using adsorption, and usually consists of two or more adsorption towers, which are filled with a solid desiccant. The entire fractionation process is broken down into steps, starting with the removal of the lighter NGLs from the stream. The recovered H2S is sent to a combined Claus-SCOT (Tail Gas Treating) unit to be converted to elemental sulfur, as was also discussed in Lesson 10. Printed: 26 April 2004 - [Natural Gas Processing Principles and Technology - Part I.doc] University of Calgary Natural Gas Processing Principles and Technology - Part I April 2004 Author: Dr. A.H Younger, P.Eng Revised and Prepared by: Dr Harald F. Thimm & Jason Sullivan Thimm Engineering Inc. 214, 3916 64th Avenue SE Calgary, Alberta T2C 2B4 [6. While water has a boiling point of 212 degrees Fahrenheit, glycol does not boil until 400 degrees Fahrenheit. The College of Earth and Mineral Sciences is committed to making its websites accessible to all users, and welcomes comments or suggestions on access improvements. The effluent gas is virtually free of sulfur compounds, and thus loses its sour gas status. The John A. Dutton e-Education Institute is the learning design unit of the College of Earth and Mineral Sciences at The Pennsylvania State University. The next logical step is NGL (Natural Gas Liquids) extraction and fractionation. To learn more about the environmental effects of sour gas treatment and flaring, click here. Extraction of the other, heavier NGLs can be close to 100 percent using this process. This basic pressure-temperature relationship can work in reverse as well, to extract gas from a liquid oil stream. Spanning the entire NG processing chain, we have delivered everything from standardized, modular designs to world-scale, stick-built NGL plants. In order to recover elemental sulfur from the gas processing plant, the sulfur containing discharge from a gas sweetening process must be further treated. Our industry-leading team of experts include process design, application and modular engineering, project management, data analysis and operations experience. Processing plants remove valuable natural gas liquids from the treated gas. In this process, a liquid desiccant dehydrator serves to absorb water vapor from the gas stream. Department of Energy’s Office of Fossil Energy, Natural Gas – From Wellhead to Burner Tip. Use industry-leading technologies for CO₂ and H₂S removal Acid gas treatment and removal technologies separate sour gases—highly corrosive CO 2 and often deadly H 2 S acid gases—from saleable natural gas streams in a process known as gas sweetening. Sour gas can also be extremely corrosive. Many of the innovations we have developed, like the use of plate-fin exchangers and packings in cryogenic columns, remain today as standard designs in the industry. Similar to using absorption for dehydration, using a different absorbing oil for hydrocarbons. Wet gas enters the separator, being cooled slightly by a heat exchanger. NGLs include ethane, propane, butane, iso-butane, and natural gasoline. Remember, the entire goal is to arrive at natural gas pipeline quality, with a standard BTU content of 1,032 BTUs per cubic foot. The scrubbers remove sand and other large-particle impurities. The actual practice of processing natural gas to pipeline-quality levels can be quite complex, but usually involves four main processes to … An example of this type of equipment is the Low-Temperature Separator (LTX). The natural gas, having been stripped of most of its water content, is then transported out of the dehydrator. The scrubbers serve primarily to remove sand and other large-particle impurities. The process for removing hydrogen sulfide from sour gas is commonly referred to as ‘sweetening’ the gas. Gas wells typically produce raw natural gas by itself, while condensate wells produce free natural gas along with a semi-liquid hydrocarbon condensate. Second, these natural gas liquids must be separated themselves, down to their base components. The last step in the processing sequence is the Natural Gas Liquids (NGL) extraction, fractionation, and treatment, as described in Figure 12.4. In order to decrease the amount of methane and other compounds that are lost, flash tank separator-condensers work to remove these compounds before the glycol solution reaches the boiler. Gas processing plants are intended to help you meet pipeline sales specifications and/or recover valuable marketable liquids from natural gas. Gas processing is an instrumental piece of the natural gas value chain. It is now a mixture of absorption oil, propane, butanes, pentanes, and other heavier hydrocarbons. To learn about the basics of natural gas, including its composition, click here. Two or more towers are required due to the fact that after a certain period of use, the desiccant in a particular tower becomes saturated with water. Natural gas that comes from oil wells is typically termed ‘associated gas’. That is, the mixed stream of different NGLs must be separated out. Sulfur can be sold and used if reduced to its elemental form. Sulfur exists in natural gas as hydrogen sulfide (H2S), and the gas is usually considered sour if the hydrogen sulfide content exceeds 5.7 milligrams of H2S per cubic meter of natural gas. When this natural gas and oil is produced, it is possible that it will separate on its own, simply due to decreased pressure; much like opening a can of soda pop allows the release of dissolved carbon dioxide. After natural gas is processed, it's then transported to market via pipelines. Most of the liquid, free water associated with extracted natural gas is removed by simple separation methods at or near the wellhead. Dropping the temperature of the gas stream to around -120°F by expansion and external refrigeration, Natural Gas Liquid Fractionation - works like Light Ends Unit, Deethanizer - separates ethane from the NGL stream. Natural gas processing plants. Glycol, the principal agent in this process, has a chemical affinity for water. Essentially, cryogenic processes consist of dropping the temperature of the gas stream to around -120 degrees Fahrenheit. m3/day) of sweet natural gas. This step is typically done at the well site. Typical desiccants include activated alumina or a granular silica gel material. The most basic type of separator is known as a conventional separator. Natural Gas Processing and Treating. The removal of natural gas liquids usually takes place in a relatively centralized processing plant, and uses techniques similar to those used to dehydrate natural gas. Essentially, fractionation occurs in stages consisting of the boiling off of hydrocarbons one by one. 2217 Earth and Engineering Sciences Building, University Park, Pennsylvania 16802 The Pennsylvania State University © 2020. This separation of natural gas from oil is most often done using equipment installed at or near the wellhead. The absorption method of NGL extraction is very similar to using absorption for dehydration. Once absorbed, the glycol particles become heavier and sink to the bottom of the contactor where they are removed. Natural gas from some wells contains significant amounts of sulfur and carbon dioxide. Then, an expansion turbine is used to rapidly expand the chilled gases, which causes the temperature to drop significantly. This gas can exist separate from oil in the formation (free gas), or dissolved in the crude oil (dissolved gas). Abstract. In addition to separating oil and some condensate from the wet gas stream, it is necessary to remove most of the associated water. In addition to processing done at the wellhead and at centralized processing plants, some final processing is also sometimes accomplished at ‘straddle extraction plants’. There are two principle amine solutions used, monoethanolamine (MEA) and diethanolamine (DEA). Methane is the gas found in natural gas, and natural gas processing is used to remove other gases and impurities. Natural gas hydrates are crystalline ice-like solids or semi-solids that can impede the passage of natural gas through valves and pipes. Although dry pipeline quality natural gas is virtually identical across different geographic areas, raw natural gas from different regions may have different compositions and separation requirements. 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