S natural gas reserves totaling 239 tcf, as stranded gas 1 2. Pdf on oct 31, 2012, michal netusil and others published natural gas dehydration find, read and cite. With this in mind, national strategic reserves are created. The sample calculations, equations and spreadsheets presented herein were developed using examples published in the engineering data book as published by gpsa as a service to the gas processing industry. Lng dehydrationdrying of natural gas absorption and refrigeration with hydrate inhibition is the most common dehydration process used to meet pipeline sales specifications. Water content of natural gas 9 gpsa engineering data book, th ed. General selection chart of natural gas dehydration method 1, with modification bonus. Poor dehydration requires further, more detailed investigation dew points below spec. The dominant components of the natural gas, particularly methane, have the ability to form hydrates if the temperature and pressure allows hydrates to form. A great deal of the vapor and liquid that is caught up in the natural gas. Comparison of methods for dehydration of natural gas stored in. This course will give you a basic understanding of the operation of a glycol dehydration system.
Calcium chloride is often mentioned as a desiccant. If there is no water present, then it is impossible for a hydrate to form. The idea of storing natural gas ng is to straighten demand and be. Dehydration is the process by which water is removed from natural gas. Glycol dehydration is a liquid desiccant system for the removal of water from natural gas and natural gas liquids ngl. Because most of the water vapor has to be removed from natural gas before it can be commercially marketed, all natural gas is subjected to a dehydration process.
Betsy casada sunday, july 23, 2017 the presence of waterwater vapor in natural gas causes hydrates solid, icelike crystals of hydrocarbons and water that form under high pressure in well streams with a low temperature which in turn cause freezing and blocking of pipelines, valves and other. Glycol dehydration is a key component of the overall process that cant be skipped over. All information and calculation formulae has been compiled and edited in cooperation with the gpa midstream association. Use features like bookmarks, note taking and highlighting while reading handbook of natural gas transmission and processing. The phase behavior for natural gas with a given composition is typicallydisplayed on a phase diagram, an. Natural gas dehydration lessons learned from the natural gas star program conocophillips the colorado oil and gas association, and the independent petroleum association of mountain states producers technology transfer workshop durango, colorado september, 2007 epa. Natural gas is considered dry when it is almost pure methane, having had most of the other commonly associated hydrocarbons removed. Tegi t i b ti tteg is most common in absorption systems meg is most common in glycol injection systems. This site is like a library, use search box in the widget to get ebook that you want.
For the same inlet data, emah 11 performed simulations of a natural gas dehydration process in aspen hysys and aspen plus using different equilibrium models in order to. When other hydrocarbons are present, the natural gas is wet. Known for being highly flammable, gas hydrates are a preventable threat that can costs millions of dollars in. The raw natural gas extracted from production wells contains many impurities that must be removed in order to achieve the speci cations of the liqui ed natural gas lng andor the pipeline gas. Natural gas phase behavior the natural gas phase behavior is a plot of pressure vs temperature thatdetermines whether the natural gas stream at a given pressure andtemperature consists of a single gas phase or two phases. Optimization of natural gas dehydration using triethylene. If there is only a small amount of water present, then the formation of hydrate is less.
When large gas volumes are transported, dehydration is the most efficient and economical means of preventing the hydrate formation in the trunk pipeline. Gas dehydration is widely used in natural gas treatment plant as a common process, because water and hydrocarbon can form hydrates ice formation which may block valve and pipelines. A recent epa survey determined that almost 36,000 glycol dehydration units are operating in the united states. Modelling of natural gas sweetening and dehydration processes. Comparison of natural gas dehydration methods 1,2 general overview of applicability of each dehydration method is shown in figure below. This stage is directed more to co2 removal since the bolivian natural gas contains.
Delta gas plant dehydration process using the hysys simulator. Natural gas is considered the dominant worldwide bridge between fossil fuels of today and future resources of tomorrow. Gas dehydration field manual ebook by maurice stewart. This paper compares three methods for natural gas dehydration that are widely. Thanks to the recent shale boom in north america, natural gas is in a surplus and quickly becoming a major international commodity. There are two basic reasons why ng storage is important. If the composition of co2 exceeded that limit it would freeze in the liquefaction process pipelines. The required outlet concentration of water in natural gas is equivalent to the dew point. However, natural gas found at the wellhead, although still composed. Contents vii disadvantages 43 plunger pumps 43 advantages 43 disadvantages 43 comparisonofhydrate prevention methods 43 overview 43 heaters 44 chemical injection 44 downholeregulators 44 summaryof hydrate prevention methods 45 hydrateinhibition 45 hammerschmidt equation 45 determinationoftotal inhibitor required 47 procedurefor. Optimization of natural gas dehydration using triethylene glycol was carried out using aspen hysys process software and regression analysis.
The petroleum industry spends millions of dollars every year to combat the formation of hydratesthe solid, crystalline compounds that form from water and small moleculesthat cause problems by plugging transmission lines and damaging equipment. Frost on exterior of tower gas temps below 30 degrees farenheit clogge trays or packing in tower unusually loud noise partially plugged trays or packing high pressure or high velocity gas tower may be undersized dew points dew points above spec. Water vapour needs to be removed from natural gas streams to meet gas specifications and to avoid corrosion and hydrate formation in process equipment and pipelines. Updated and more practical than ever, natural gas hydrates, third edition helps managers and engineers get up to speed on all the most common hydrate types, how to forecast when they will appear, and safely mitigate their removal. Two subsea natural gas treatment processes, namely natural gas dehydration and acid gas removal, are discussed in details with respect to the advantages and challenges in the implementation of. Final report novel membranes for natural gas dehydration. Dehydration is necessary to ensure smooth operation of gas transmission lines prevents the formation of gas hydrates and reduces corrosion. Gas dehydration chapter 11 based on presentation by prof. Principles and practices kindle edition by mokhatab, saeid, poe, william a. The natural gas used by consumers is composed almost entirely of methane. The equipment that extracts this liquid gold is expensive and sensitive to liquids. One of the problems with some of this natural gas is that it is in remote areas where there is little or no local use for the gas.
The theme of natural gas ng dehydration is closely linked with storage of natural gas. The water content of the gas can be calculated using the. This is a common method used for preventing hydrate formation. Nearly 50 percent worldwide natural gas reserves of 6,254.
The natural gas industry has recognized that dehydration is necessary to ensure smooth operation of gas transmission lines. Dehydration of natural gas is the removal of the water that is associated with natural gases in vapor form. One of the most common methods for removing the water from produced gas is glycol. Water also can cause corrosion in the presence of acid gas component in natural gas. It is one of the cleanest, safest and most useful of all energy. Glycol dehydrators, part of natural gas dehydration systems, remove water vapor from gas streams to prevent the formulation of hydrates and corrosion in pipelines. Click download or read online button to get natural gas hydrate book now. All raw natural gas is fully saturated with water vapor when produced from an underground reservoir. Dehydration of natural gas is needed to remove the water that is associated with natural gases in vapor form. Produced gas is saturated with water, which must be removed for gas transmission glycol dehydrators are the mostcommon equipment to remove water from gas 36,000 dehydration systems in natural gas production, gathering, and boosting most use triethylene glycol teg glycol dehydrators create emissions methane, vocs, haps from reboiler vent. Glycol dehydration troubleshooting guide oil and gas. In the transmission of natural gas further condensation of water is problematic.
As an introduction, the book provides different concepts and theories that describe the gas processing industry. The existing methods for gas dehydration in the field fall. Rarely covered in formal engineering courses, natural gas hydrates are a common problem and reallife danger for engineers worldwide. At the same time, the petrochemical industry with its new plastic materials quickly increased production. Although dehydration historically has been a fairly inexpensive step in the upgrading of natural gas to pipeline quality, costs are increasing. Handbook of natural gas transmission and processing. It is said to be applicable if water removal demand is not too big and the plant is on the low capacity side. It is the most common and economical means of water removal from these streams. This treatment consists of dehydrating the natural gas, which is accomplished by lowering the dew point temperature of the gas at which water vapor will. First, co2 and h2s removal stage which is constructed to assure that co2 would not exceed 50 ppm in the natural gas feed. When i read several literatures related to natural gas dehydration, the. It can increase pressure drop in the line and often leads to corrosion problems.
Several natural gas dehydration methods and range of. With all units optimally specified during the process, the lean teg inflow rate was varied with the water content in. Glycol dehydration cannot get to these low water levels mole sieves used for this. The glycol dehydration unit is a reliable, efficient system for removing water from natural gas well streams in order to meet typical pipeline and process. More than 90 percent of these systems 34,000 treat natural gas at flow rates averaging less than 10 mmscfd, the range in which a membrane process is more cost effective than glycol dehydration. Unless gases are dehydrated, liquid water may condense in pipelines and accumulate at low points along. Comparison of three methods for natural gas dehydration. Even now, gas production is gaining market share as liquefied natural gas lng provides an economical way. Secondly, ng storage enables the maximum capacity of distribution lines to be exploited. It discusses the various designs and operations in a gas processing facility. Introduction natural gas is a combustible mixture of hydrocarbon gases and a vital component of the worlds supply of energy.
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