The wet gas first enters a two-phase separator (not shown in Figure 4-11), so that the liquid can be removed from the gas mixture. Uses RF-22 as the refrigerant or working fluid. Factors that must be considered in the design of these heat exchangers include: The effect of glycol on heat exchanger pressure drop, The reduction in heat transfer due to the presence of glycol, Continuous changes in flow regime across the heat exchanger tubes, Maximum allowable tube length as a function of tube diameter, Maximum allowable velocity to prevent emulsion formation, Minimum allowable velocity to maintain the glycol in the annular flow regime, Saeid Mokhatab, ... John Y. Mak, in Handbook of Natural Gas Transmission and Processing (Fourth Edition), 2019.

Typically, a packed column located below the reboiler section is used for TEG stripping. The natural gas dehydration process is selected based on the water dew point requirements, as shown in Fig. It is desirable to operate the stabilizer pressure as high as possible to minimize gas compression cost. As stated earlier, the choice between inhibitor alternatives must be based on physical limitations as well as economics. However, the industrial application of kinetic inhibitors depends on the repeatability of multiphase pipeline testing results among laboratory, pilot plant, and field, and the transferability among different plants. The dry gas then flows through a glycol cooler to cool the hot regenerated glycol before the glycol enters the absorber. The process flow schematic for a glycol injection dehydration system is shown in Figure 7-6.

This still “wet” gas then enters the bottom of the glycol gas absorber, flows upwards through the trayed or packed tower with mist eliminator to remove any entrained glycol droplets from the gas stream, and exits on the top of the absorber as dry gas. The very tough and relatively hard materials based on polyurethane, polyester, or polyamide hard segments are generally regarded as premium products [10–12]. For ethylene oxide (EO) and ethylene glycol (EG), the equations for the reactions are as follows: Features. The glycol dehydration process is an example of a process that provides absorption dehydration, and in the process, a liquid desiccant provides the means to absorb water from the gas stream. The stabilizer pressure is selected based on NGL liquid composition. Therefore, this method of treatment is a cost-effective solution for the control of gas hydrates. Glycol and water separate in the cold separator where they are routed to a regenerator, the water is boiled off and the glycol is circulated back to be injected into the inlet stream. FIGURE 3-22. 1.16). As for the use of silica gel dehydration process, because of its limited short cycle time, it is more suitable for polishing services, such as membrane separator pretreatment, and fuel gas conditioning rather than feed gas to a gas processing plant. The glycol solution, bearing all of the water stripped from the natural gas, is put through a specialized boiler designed to vaporize only the water out of the solution where the boiling point differential facilitates removal of the water for the makes it relatively easy to remove water from the glycol solution after which the glycol is recycled to the contactor. This free PDF Converter online tool is powered by PDFRock – a PDF Converter powered platform that enables you to convert PDF to Word (PDF to DOC, PDF to DOCX), PDF to PowerPoint (PDF to PPT, PDF to PPTX). A high separator pressure would lower the recompression requirement of the residue gas. Gas-to-gas exchange is very common in NGL recovery processes.

A crude ethylene glycol mixture is then produced by the hydrolysis of EO with water under pressure. It can also be accomplished with a TEG dehydration unit followed by propane chilling. Ethylene glycol is used because of its low cost and at low temperatures it is not lost in the gas phase.

Hydrocarbon dew pointing using Joule–Thomson process (Mokhatab et al., 2015). Glycol injection is preferred by most pipeline operators because of its simplicity. If high propane recovery is required, a deep hydrocarbon dew pointing process (Fluor Process) can be used which can recover over 95% propane (see Section 11.3.3). Many different flow schemes are used for glycol injection systems. Their suggested applications include blends with polyethylene or polypropylene and partial replacement of polypropylene in S-EB-S/polypropylene/oil blends.

Figure 7-6. J-T, Joule–Thomson; LC, level controller; NGL, natural gas liquid; PC, pressure controller; TEG, triethylene glycol. The liquid mixture from the primary separator is generally warmed in a fired heater or by heat exchange with the sales gas to reduce liquid viscosities. This allows for even glycol distribution.

From A to B indicates gas-to-gas exchange; from B to C, chilling. For small gas processing plant operation, J-T is the technology of choice to produce on-spec hydrocarbon dew point gas for sales.

Molecular sieves can be designed to remove mercaptans to meet the sulfur specifications. The water-glycol mixture is fed to evaporators where the water is recovered and recycled. The most widely used solvent absorption is glycol compounds. 11.4. If hydrocarbons dew point control is required, cooling with inhibitor, such as the use of ethylene glycol injection with propane chilling or the use of silica gel can be suitable. Figure 11.4.

However, operating conditions may also limit the number of available choices.

Where NGL export pipeline does not exist, the stabilizer can be operated at a lower pressure, to produce a condensate product, typically with 10 psia vapor pressure. M. Ibrahim Khan, M.R. As shown in Fig. Ethylene glycol is generally preferable to diethylene or triethylene glycol for this type of operation because it is less soluble in liquid hydrocarbons, and liquid hydrocarbons are less soluble in ethylene glycol than in the higher glycols. However, even if the hydrocarbon dew point were met, the product gas still may not meet the specifications on heating value and Wobbe Index, if the ethane content is high, such as the shale gas. Inlet gas is cooled to a low enough temperature to condense the desired fraction of LPG and NGL. The dilute aqueous solutions have the further advantage of low solubility in liquid hydrocarbons.

ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. URL:, URL:, URL:, URL:, URL:, URL:, URL:, URL:, Absorption of Water Vapor by Dehydrating Solutions, Gas Sweetening and Processing Field Manual, Transportation, Processing, and Refining Operations, The Petroleum Engineering Handbook: Sustainable Operations, Recently, two new types of low-dosage inhibitors have been developed, which will enable the subsea gas transmission pipelines to handle increased gas volumes without additional, Introduction to Natural Gas Processing Plants, Modeling, Control, and Optimization of Natural Gas Processing Plants, Applied Plastics Engineering Handbook (Second Edition), Handbook of Natural Gas Transmission and Processing (Third Edition), Wet gas can be chilled to meet pipeline water as well as hydrocarbon dew point specification using the, Natural Gas Dehydration and Mercaptans Removal, Handbook of Natural Gas Transmission and Processing (Fourth Edition), Journal of Natural Gas Science and Engineering. Kinetic inhibitors should be considered for residence times of less than a few minutes. If there is a decrease in flow, this may be an indication that the spray nozzles are plugged. Simplified flow diagram of a refrigeration plant. Design techniques for these exchangers are based on empirical data. Gas and liquid are separated in the cold separator, which is a three-phase separator. For water dew pointing lower than −40°F and down to −80°F, the enhanced TEG dehydration process, such as DRIZO, is suitable. The mixture is then fed to the oil-glycol separator, the oil is removed as product, and the glycol is sent to the regenerator where it is reconcentrated for reuse. 1.16, dried gas from the TEG dehydration unit is cooled with the cold separator vapor in a gas/gas shell and tube heat exchanger. A well-designed glycol injection dehydration system should provide sufficient glycol delivery pressure from the glycol regeneration unit for an even spray pattern.

The gas is called “plant residue” and is the outlet gas from the plant. When glycol is sprayed onto the tube sheet and the glycol solution is cooled, the viscosity of the glycol solution increases.

Gas dehydration technology selection. Hydrocarbon dew point controlling using the J–T process. The solvent required by the DRIZO process is usually obtained from the C6+ (BTEX) present in the natural gas itself and in most cases the process will produce some liquid hydrocarbons. These chemicals are called “kinetic inhibitors” and “anti-agglomerant inhibitors”.

In cold oil plants operating in the −40°F range, the separation of the glycol-water mixture from the hydrocarbon condensate may be accomplished at the low contact temperature. Figure 2-5.

the solution is pumped through preheaters (hot recycle water and steam ) Flow diagram of process employing glycol injection and cooling to dehydrate natural gas. Alternatively, the feed gas can be dried using the TEG dehydration system. The water is absorbed into the glycol, while the liquid hydrocarbons form a separate phase. Figure 11-39.

The process selection can be quite straight forward. Geoffrey Holden, in Applied Plastics Engineering Handbook (Second Edition), 2017. Typical glycol dehydration process is suitable for meeting pipeline gas specification as low as −40°F and is more economical than molecular sieves technology. However, high pressure also reduces the relative volatility between components, making removal of the desirable products difficult.

RF-22 (which is cooled in a refrigeration cycle to −40 °F) is able to cool the gas to approximately −40 °F. The glycol dehydration process is an example of a process that provides absorption dehydration, and in the process, a liquid desiccant provides the means to absorb water from the gas stream. For Y-grade NGL production, the stabilizer operates as a demethanizer, heated with steam or a heat medium. 5.3 Shell High-Efficiency Ethylene Glycol Process: Product Value of EG as a Function of Plant Operating Level and Plant Capacity 5-30 6.1 Dow High-Efficiency Ethylene Glycol Process Process Flow Diagram ..... E-7 6.2 Dow High-Efficiency Ethylene Glycol Process: Glycol injection heat exchanger design: The tube side inlet nozzle of the gas–gas exchanger is typically designed with a cone inlet channel designed with a specific angle and oriented in an axial position. However, high pressure also makes phase separation more difficult, requiring a larger separator. TECHNOLOGY TRENDS Recent technology trends in ethylene oxide and ethylene glycol processes involve research and development in the process and equipment design and catalysts utilized in their production. Wet gas can be chilled to meet pipeline water as well as hydrocarbon dew point specification using the glycol injection process, which includes propane refrigeration for chilling.