WO2007146610A2 - Optimisation du démarrage d'un accumulateur à reflux dans un système de régénération d'amines - Google Patents

Optimisation du démarrage d'un accumulateur à reflux dans un système de régénération d'amines Download PDF

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Publication number
WO2007146610A2
WO2007146610A2 PCT/US2007/070115 US2007070115W WO2007146610A2 WO 2007146610 A2 WO2007146610 A2 WO 2007146610A2 US 2007070115 W US2007070115 W US 2007070115W WO 2007146610 A2 WO2007146610 A2 WO 2007146610A2
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WIPO (PCT)
Prior art keywords
amine
stream
rich
lean
still
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2007/070115
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English (en)
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WO2007146610A3 (fr
Inventor
Roy Wade Rhodes
Ii Quenten Zane Rhodes
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Newpoint Gas Services Inc
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Newpoint Gas Services Inc
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Filing date
Publication date
Application filed by Newpoint Gas Services Inc filed Critical Newpoint Gas Services Inc
Publication of WO2007146610A2 publication Critical patent/WO2007146610A2/fr
Anticipated expiration legal-status Critical
Publication of WO2007146610A3 publication Critical patent/WO2007146610A3/fr
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C213/00—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton
    • C07C213/10—Separation; Purification; Stabilisation; Use of additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1425—Regeneration of liquid absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1456—Removing acid components
    • B01D53/1462—Removing mixtures of hydrogen sulfide and carbon dioxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/06—Polluted air
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Definitions

  • This invention relates to the regeneration of amine used in the processing of natural gas.
  • the invention particularly relates to novel component configurations to increase ease of startup and operations for the amine regeneration system; and most particularly to the optimization of reflux accumulator operation by incorporation of direct injection of amine solution.
  • Acid gas removal from gas streams is necessary to allow this gas to be used and/or sold into pipeline systems.
  • the removal of sulfur compounds from these acid gasses or "sour gasses” is called “sweetening.”
  • acid gases are removed using an amine-based solvent to absorb the acid gas via various chemical reactions, resulting in the production of a rich amine solvent, which can then be regenerated using heat.
  • Hydrogen sulfide is a toxic gas that must generally be removed to extreme low concentrations (less than 0.25 grains OfH 2 S per 100 standard cubic feet) prior to pipeline delivery. When mixed with free water it forms a weak acid that can cause corrosion.
  • Carbon dioxide is a non-toxic inert gas. Carbon dioxide, as such, is harmless in dry natural gas but when mixed with free water will form a weak acid and also cause corrosion.
  • Inlet gas to cryogenic plants that contain concentrations of CO 2 in excess of 0.75 to 1.0 percent CO 2 may cause freezing problems. The CO 2 will freeze to a solid ice in a turbo expander plant demethanizer where it may plug lines and even plug the tower itself. Often flooding of the demethanizer results from carbon dioxide freezing within the tower.
  • the plant inlet gas contains concentrations of carbon dioxide too high to process, all of the gas may be treated or part of the gas may be separated into a side stream and treated by an amine plant. Principally all the carbon dioxide is removed in the amine plant.
  • absorption processes the gas stream contacts a liquid that selectively removes acid gases.
  • the most common absorption process is the amine process.
  • the liquid absorbent is a mixture of water and a chemical amine, usually monoethanol-amine (MEA) or diethanolamine (DEA).
  • MEA monoethanol-amine
  • DEA diethanolamine
  • TEA triethanol-amine
  • DGA diglycolamine
  • MDEA methyl-diethanolamine
  • diisopropylamine sulfanol and solutions of these, with special additives to improve efficiencies, are utilized.
  • Amines remove carbon dioxide and hydrogen sulfide by a chemical reaction that changes the chemical form of both the amine and the acid gases.
  • the new chemical changes the acid gases to a liquid form which is separated from the acid-free gas or sweetened gas.
  • the chemical reaction between amine (called lean amine at the start of the process) and acid gases gives off heat when the reaction takes place.
  • the sweet residue gas flows out the top of a contactor or absorber and the reacted amine (also called rich amine) flows out the bottom and is generally higher in temperature than the inlets.
  • Lean amine is regenerated by reducing the pressure and adding heat to the rich amine.
  • amine-based solvents include secondary and tertiary amines (e.g., diethanolamine [DEA], and/or methyldiethanolamine [MDEA]), which are generally more energy efficient than primary amines due to their lower heat of reaction and lower energy requirements for regeneration.
  • Secondary amine solvents may further include monoethanolamine [MEA], diglycolamine [DGA], triethanolamine [TEA], diisopropylamine, and various combinations thereof, along with one or more additives.
  • the effectiveness of a particular amine solvent to absorb acid gases to meet the treated gas specification typically depends on the residual acid gas content in the lean amine, which in turn is a function of the particular regeneration method and conditions.
  • U.S. Patent 4,152,217 to Eisenberg et al teaches an amine regeneration system which utilizes a split rich amine stream wherein one stream is routed directly to the top of an amine regenerator column and the second stream is routed to a heat exchanger where it is heated en route to an intermediate point of the regenerator column.
  • the spent amine stream which is passed without prior heating directly to the top of the regenerator column is heated by condensing steam in the column which would normally escape therefrom, thereby reducing the amount of "saturation" steam which is lost from the system, thereby reducing the overall energy requirements for the system.
  • U.S. Patent 4,461,749 to Thorn is directed to a method of processing acid gases wherein makeup water is distilled internally in an amine gas treating unit by adding it to the reclaimer used to process a slipstream of lean amine from the stripper.
  • U.S. Patent 4,798,910 to Herrin teaches a method for amine regeneration wherein a rich amine out of a first heat exchanger is temperature controlled prior to transfer to a second heat exchanger. At least a portion of the hot overhead gasses exiting from a stripping still are transferred to the second heat exchanger. Temperature controlled heated rich amine liquid passes through the second exchanger and contacts the hot overhead gasses. The rich amine liquid is increased in higher temperature thereby and then is transferred to yet a third exchanger and finally to the stripping still for regeneration of lean amine. The reduced temperature overhead gasses are transferred to the reflux condenser for final cooling.
  • U.S. Pat. No. 6,071,484 to Dingman, et al. describe a method to produce an ultra lean amine using an ion exchange bed to remove the residual acid gases in the lean amine.
  • U.S. Pat. No. 4,798,910 to Herrin teaches the use of an additional heat exchanger to heat the rich amine solvent using a portion of the heat content in the regenerator overhead gases. This method reduces overhead condenser duty to some degree, however reboiler duty remains largely unaffected, as the amine regeneration process is more strongly dependent on the stripping steam supplied at the bottom of the regenerator.
  • U.S. Pat. No. 3,565,573 to Thirkell teaches a process in which acid gas is treated in a dual-zone absorber to provide a rich solvent that is regenerated in conventional manner.
  • U.S. Pat. No. 3,829,521 to Green et al similarly describe a configuration in which a pre-stripper and a stripper operate in series to remove acid gas from two gas streams.
  • H 2 S hydrogen sulfide
  • CO 2 carbon dioxide
  • Amine plants are typically employed for the removal of the first two contaminants listed (hereto referred to as "acid gas").
  • an amine based solvent is brought in contact with the natural gas stream. The amine adsorbs the acid gas and then the amine is regenerated, which means that the acid gas in the amine is removed so the amine can be reused.
  • the method for regeneration utilizes a reboiler to create steam that comes into contact with the amine.
  • the steam has two purposes: to provide heat that allows the endothermic de-adsorption of the acid gas to occur and to reduce the partial pressure of the acid gas in the vessel. This reduction in partial pressure allows the amine to be regenerated at much higher purities than would otherwise be possible.
  • the amine is then cooled and reused to treat the natural gas.
  • an improved process for amine regeneration is provided via a system including a rich/lean heat exchanger, a still, a reflux condenser, a reflux accumulator, a pump, and a reboiler, wherein the improvement comprises the provision of a reflux accumulator f ⁇ li line, and associated flow control valving, so as to provide direct injection of amine solution, thereby enabling an operator to instantly set the liquid level in the reflux accumulator, to enhance start-up efficiency.
  • Figure 1 shows the flow of contaminated amine through its separation into clean amine and acid gas, and illustrates the reflux accumulator fill line in accordance with the present invention
  • Figure 2 shows a similar prior art process absent the reflux accumulator fill line utility.
  • DETAILED DESCRIPTION OF THE INVENTION The present invention focuses on the lean amine regeneration process.
  • the solution regeneration generally takes place in a low pressure still with a reboiler at the bottom to furnish heat to the solution.
  • the still is generally a bubble tower containing either trays or packing.
  • the rich amine liquid containing the sour gasses (CO 2 and H 2 S) is injected into the still near the top and flows down the tower while steam generated in the reboiler flows up the tower countercurrent to the descending rich amine.
  • the steam aids in "stripping" the sour gasses from the rich amine liquid and sends them back up the tower and out the top of the tower.
  • the heat added to the still reboiler increases the temperature of the amine somewhat, but most of the heat goes into generating steam which, in turn, flows into and up the still.
  • This heat added or inputted into the reboiler must be furnished from an outside source such as steam from another process, hot oil or hot glycol circulated through the reboiler, or fuel directly fired into the reboiler.
  • an outside source such as steam from another process, hot oil or hot glycol circulated through the reboiler, or fuel directly fired into the reboiler.
  • This overhead steam and gas stream (called overhead) is generally higher in temperature than the feed to the top of the still.
  • a condenser called a reflux condenser
  • the novelty of the process and apparatus resides in the use of the reflux accumulator fill line to set the initial level in the reflux accumulator.
  • the amine plants control system protects the pump from running without fluid.
  • the "level gauge" needs to sense a liquid level in order for the amine plant to continue running.
  • This fault must be manually overridden by an operator and the operator must remain with the plant until the condensed water accumulates to the appropriate level, which can take up to a few hours. Simply adding water to the accumulator is not a viable option since such addition will unacceptably change the concentration of water in the system.
  • a reflux accumulator pressurization assembly comprised of an amine line and associated valving, provides a fluidic connection between the rich amine and the reflux accumulator.
  • the take-off of the rich amine stream for forwarding to the reflux accumulator may be before or after the rich/lean heat exchanger (note dashed line after rich/lean heat exchanger).
  • the valve can be opened to enable setting of a liquid level within the reflux accumulator, as desired, thereby optimizing start-up and greatly saving time and effort.
  • the contaminated amine is introduced into the rich/lean heat exchanger causing the rich amine to be heated.
  • the rich amine is then introduced into the still where it comes in contact with steam as it goes down through the still.
  • the amine releases the acid gas components which exit the still with the steam and they are carried into the reflux condenser.
  • the steam condenses in the reflux condenser, and then the water stream enters the reflux accumulator where the acid gas exits the system.
  • the condensed water is stored in the reflux accumulator until it is pumped back into the still.
  • the amine exits the still and enters the reboiler where it is heated to release steam which is fed into the still.
  • the fully regenerated amine is passed into the rich/lean heat exchanger where it is cooled and exits the system as fully regenerated amine.
  • the reflux condenser level is set for startup using the reflux accumulator fill line and valve assembly as shown.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Gas Separation By Absorption (AREA)
  • Treating Waste Gases (AREA)

Abstract

L'invention concerne un système d'optimisation du démarrage d'un système de régénération d'amines comprenant un échangeur de chaleur riche/pauvre, un alambic, un condensateur à reflux, un accumulateur à reflux, une pompe, un rebouilleur, et un assemblage de conduite de remplissage d'accumulateur à reflux.
PCT/US2007/070115 2006-06-09 2007-05-31 Optimisation du démarrage d'un accumulateur à reflux dans un système de régénération d'amines Ceased WO2007146610A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US81205206P 2006-06-09 2006-06-09
US60/812,052 2006-06-09

Publications (2)

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WO2007146610A2 true WO2007146610A2 (fr) 2007-12-21
WO2007146610A3 WO2007146610A3 (fr) 2009-04-02

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009148715A1 (fr) 2008-05-30 2009-12-10 General Electric Company Élimination du dioxyde de carbone d’un gaz de synthèse à pression élevée
US10646818B2 (en) 2016-07-05 2020-05-12 Ineos Americas, Llc Method and apparatus for recovering absorbing agents in acid gas treatment

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1096851A (en) * 1965-01-06 1967-12-29 Power Gas Ltd Improvements in or relating to the separation of acidic gases from gaseous mixtures
US4106916A (en) * 1977-08-10 1978-08-15 Phillips Petroleum Company Automatic control of an absorption/stripping process
US4152217A (en) * 1978-06-30 1979-05-01 Exxon Research & Engineering Co. Amine regeneration process
US6531103B1 (en) * 2000-03-09 2003-03-11 Union Carbide Chemicals And Plastics Technology Corporation Process for removing sulfur compounds from gas and liquid hydrocarbon streams
FR2848218B1 (fr) * 2002-12-10 2005-01-28 Inst Francais Du Petrole Procede de desacidification et de deshydratation d'un gaz naturel

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009148715A1 (fr) 2008-05-30 2009-12-10 General Electric Company Élimination du dioxyde de carbone d’un gaz de synthèse à pression élevée
US8696797B2 (en) 2008-05-30 2014-04-15 General Electric Company Carbon dioxide removal from synthesis gas at elevated pressure
US10646818B2 (en) 2016-07-05 2020-05-12 Ineos Americas, Llc Method and apparatus for recovering absorbing agents in acid gas treatment
US11433347B2 (en) 2016-07-05 2022-09-06 Ineos Americas, Llc Method and apparatus for recovering absorbing agents in acid gas treatment
US12102958B2 (en) 2016-07-05 2024-10-01 Ineos Americas, Llc Method and apparatus for recovering absorbing agents in acid gas treatment

Also Published As

Publication number Publication date
WO2007146610A3 (fr) 2009-04-02

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