WO2014169245A1 - Production de vapeur à vidange réduite - Google Patents

Production de vapeur à vidange réduite Download PDF

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Publication number
WO2014169245A1
WO2014169245A1 PCT/US2014/033860 US2014033860W WO2014169245A1 WO 2014169245 A1 WO2014169245 A1 WO 2014169245A1 US 2014033860 W US2014033860 W US 2014033860W WO 2014169245 A1 WO2014169245 A1 WO 2014169245A1
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WO
WIPO (PCT)
Prior art keywords
steam
boiler
tds
evaporator
blowdown
Prior art date
Application number
PCT/US2014/033860
Other languages
English (en)
Inventor
Scott Macadam
Original Assignee
Conocophillips Company
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Conocophillips Company filed Critical Conocophillips Company
Priority to CA2902612A priority Critical patent/CA2902612A1/fr
Publication of WO2014169245A1 publication Critical patent/WO2014169245A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22G—SUPERHEATING OF STEAM
    • F22G1/00—Steam superheating characterised by heating method
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
    • E21B43/2406—Steam assisted gravity drainage [SAGD]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B1/00—Methods of steam generation characterised by form of heating method
    • F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
    • F22B1/08—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being steam
    • F22B1/14—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being steam coming in direct contact with water in bulk or in sprays
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B1/00—Methods of steam generation characterised by form of heating method
    • F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
    • F22B1/18—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/48—Devices for removing water, salt, or sludge from boilers; Arrangements of cleaning apparatus in boilers; Combinations thereof with boilers

Definitions

  • the present invention relates generally to methods and systems for generating steam with reduced blowdown levels.
  • SAGD steam assisted gravity drainage
  • thermal recovery processes include steam flooding and the cyclic steam stimulation, otherwise known as the "huff and puff method. Each of these methods typically has their steam requirements produced onsite in proximity to the reservoir steam injection wells.
  • Blowdown is the amount of water as a ratio of boiler feedwater that is discarded from the boiler, usually from mud drum of the boiler to provide an effluent stream for removing the dissolved solids that would otherwise build-up in the boiler.
  • Low boiler blowdown rates could be achieved by using low blowdown boilers such as drum boilers or forced circulation steam generators. These boilers would enable blowdown rates of only about 2-5% but would require feedwater with significantly lower TDS levels to mitigate against the scaling and fouling issues.
  • water with such lower TDS levels is typically not readily available at SAGD sites.
  • lower TDS levels could be attained by using alternate water treatment technologies such as mechanical vapor compression (MVC) evaporators, these technologies however would impose significant capital and operating cost on the SAGD surface facility. Such increased costs would make such conventional technologies economically unattractive.
  • MVC mechanical vapor compression
  • the present invention relates generally to methods and systems for generating steam with reduced blowdown levels.
  • a method for generating steam for use in a steam assisted gravity drainage (SAGD) thermal recovery process using high total dissolved solids (TDS) boiler feedwater comprises the steps of: introducing the high TDS boiler feedwater to a boiler wherein the boiler comprises an evaporator; generating low quality steam in the evaporator from the high TDS boiler feedwater; separating the low quality steam into a vapor fraction and a liquid blowdown stream; introducing the vapor fraction to a superheater to superheat the vapor fraction into superheated steam wherein the superheater is external to the boiler; allowing the liquid blowdown stream to exchange heat with the superheated steam to vaporize a portion of the blowdown stream to form a finished steam and a waste stream; introducing the finished steam to the SAGD process.
  • SAGD steam assisted gravity drainage
  • a method for generating steam using high total dissolved solids (TDS) boiler feedwater comprises the steps of: introducing the high TDS boiler feedwater to a boiler wherein the boiler comprises an evaporator; generating low quality steam in the evaporator from the high TDS feedwater; separating the low quality steam into a vapor fraction and a liquid blowdown stream; introducing the vapor fraction to a superheater to superheat the vapor fraction into superheated steam; and allowing the liquid blowdown stream to exchange heat with the superheated steam to vaporize a portion of the blowdown stream to form a finished steam and a waste stream.
  • TDS total dissolved solids
  • the superheater is a separately-fired heater external to the boiler and is retrofitted to an existing SAGD boiler system.
  • FIG. 1 illustrates a simplified example of a steam generation system using boiler feedwater with a high level of total dissolved solids (TDS) while still maintaining a relatively low boiler blowdown rate in accordance with one embodiment of the present invention.
  • TDS total dissolved solids
  • Figure 2 illustrates a simplified example of a steam generation system similar to Figure 1 but where the superheater is a separately-fired heater from boiler, in accordance with one embodiment of the present invention.
  • Figure 3 illustrates an evaporator with drum boiler.
  • Figure 4 illustrates a process with superheated steam vaporization of evaporator blow-down.
  • the present invention relates generally to methods and systems for generating steam with reduced blowdown levels.
  • a method for generating steam uses high total dissolved solids (TDS) boiler feedwater.
  • the high TDS boiler feedwater is introduced to a boiler.
  • the boiler is adapted to generate low quality steam from the high TDS feedwater.
  • the low quality steam maintains wet conditions in the boiler tubes to mitigate against fouling and scaling problems.
  • the low quality steam is then separated into a vapor fraction and a liquid blowdown stream and the vapor fraction is introduced to a superheater to superheat the vapor fraction into superheated steam.
  • the liquid blowdown stream is allowed to exchange heat with the thus-created superheated steam to vaporize a portion of the blowdown stream to form a finished steam and a waste stream.
  • This use of the superheated steam reduces the overall amount of blowdown routed to waste and has the added advantage of creating even more end user steam.
  • the finished steam may then be routed to its ultimate end use, for example, a hydrocarbon thermal recovery process such as a SAGD process.
  • FIG. 1 illustrates a simplified example of a steam generation system using boiler feedwater with a high level of total dissolved solids (TDS) while still maintaining a relatively low boiler blowdown rate in accordance with one embodiment of the present invention.
  • steam generation system 100 is shown generating finished steam 153 from boiler feedwater 113.
  • boiler feedwater 1 13 feeds boiler steam tubes 115 of boiler 105.
  • Fuel 123 and oxidant 125 combust at burner 120 to produce hot combustion gases for heating boiler steam tubes 1 15.
  • the combustion gases exit boiler 105 as flue gas 127.
  • This heat of combustion converts boiler feedwater 1 13 to low quality steam 1 17.
  • low quality steam refers to steam having a quality of from about 60 percent to about 90 percent saturated steam.
  • maintaining wet conditions in boiler steam tubes 1 15 reduces the scaling and/or fouling problem that would otherwise occur when using a boiler feedwater having a high TDS level.
  • Low quality steam 1 17 is not ready yet for use by end users.
  • the amount of water in low quality steam 1 17 would likely pose significant water hammer and erosion problems to downstream pipe if the water component were not removed before sending low quality steam 1 17 to end users.
  • low quality steam 117 is routed to separator 130 to separate low quality steam 117 into vapor fraction 135 and blowdown stream 133.
  • Vapor fraction 135 must be further superheated before transmission to end user(s) 190. Failure to superheat vapor fraction 135 before sending to end user(s) 190 would result in undesirable condensate buildup from vapor fraction 135 due to heat losses and pressure drop that would inevitably occur during transmission of vapor fraction 135 to end user(s) 190. To superheat vapor fraction 135, vapor fraction 135 is routed to superheater 140 which heats vapor fraction 135 above its saturation temperature to form superheated steam 143.
  • blowdown stream 133 Because of the high TDS level in boiler feedwater 1 13, the flowrate of blowdown stream 133 must be sufficiently high to remove the dissolved solids from boiler 105. This relatively high flowrate of blowdown stream 133 would ordinarily introduce a series of disadvantageous costs. First, all blowdown for which another end use is not found must be treated and disposed of. The treatment costs of boiler blowdown naturally increases with increased blowdown flowrate. Consequently, any reduction in the amount of boiler blowdown significantly reduces water treatment savings, by avoiding the larger water treatment that would otherwise be required and by realizing lower ongoing water treatment costs due to the reduced boiler blowdown.
  • One way of reducing the amount of blowdown is to allow superheated steam 143 to vaporize all or a portion of blowdown stream 133.
  • superheated steam 143 exchanges heat with blowdown stream 133 in heat exchanger 150.
  • Heat exchanger 150 is any heat exchanger suitable for exchanging heat between these two streams, including, but not limited to, a closed heat exchanger, a mixing vessel which allows the streams to intimately mix, or any combination thereof.
  • heat exchanger 150 produces waste stream 155 and finished steam 153 suitable for routing to end user(s) 190.
  • End user(s) 190 may include any hydrocarbon thermal recovery process, including, but not limited to, a SAGD process.
  • Waste stream 155 is the remaining liquid stream or solids which were not vaporized by superheated steam 143 in heat exchanger 150. Thus, the total amount of blowdown from steam generation system 100 is reduced, which in turn reduces the amount of flow that must be treated in water treatment facilities.
  • FIG. 2 illustrates a system similar to Figure 1, using like-reference numerals for like-elements where each like-reference numeral begins with a "2" instead of a "1."
  • boiler 205 and superheater 240 are separately-fired heaters.
  • Boiler 205 is fired by fuel 223A and oxidant 225A at burner 220A to produce hot combustion gases 227A for vaporizing boiler feedwater 213 in superheater steam tubes 240A.
  • superheater 240 is a separately-fired heater fired by fuel 223B and oxidant 225B at burner 220B to produce hot combustion gases 227A. This heat of combustion converts boiler feedwater 213 to low quality steam 217.
  • low quality steam refers to steam having a quality of from about 60 percent to about 90 percent saturated steam.
  • Low quality steam 217 is routed to separator 230 to separate low quality steam 217 into vapor fraction 235 and blowdown stream 233.
  • Vapor fraction 235 must be further superheated before transmission to end user(s) 290.
  • Vapor fraction 235 is routed to superheater 240 which heats vapor fraction 235 above its saturation temperature to form superheated steam 243.
  • Figure 3 illustrates a system similar to Figure 1 , using like-reference numerals for like-elements where each like-reference numeral begins with a "3" instead of a "1.”
  • boiler 305 is preceded by a mechanical vapor compression evaporator 360
  • Example 1 Superheater with blow-down evaporation
  • a process analysis was performed to quantify the performance of the embodiment depicted in Figure 1.
  • the 427°C superheated blow-down reduces the feedwater flowrate, and consequently the capacity of the water treatment plant, by 25%, at the cost of a slight increase in the natural gas firing rate.
  • the reduced water treatment capacity represents a significant savings to a SAGD surface facility.
  • Example 2 Enhanced mechanical vapor compression evaporator
  • FIG. 3 demonstrates water treatment and steam generation process utilized in some SAGD applications.
  • De-oiled SAGD produced water and make-up water is delivered to a produced water evaporator as feed (stream 1).
  • the evaporator is typically a mechanical vapor compression (MVC) evaporator that produces evaporator distillate, at near atmospheric pressure conditions. This distillate is relatively high in purity, with TDS levels ⁇ 100 ppm, and is suitable as boiler feed water (BFW) for drum boilers.
  • MVC mechanical vapor compression
  • BFW boiler feed water
  • this system is distinct from the other SAGD system comprising warm lime softening (WLS) and once through steam generators (OTSGs), where the OTSG BFW contains 2,000-8,000 ppm TDS.
  • WLS warm lime softening
  • OTSGs steam generators
  • the drum boiler in Figure 3 converts the clean BFW into saturated steam that is delivered to the SAGD well pads.
  • the drum boiler blow-down typically 2-5% of the BFW flowrate, is recycled to the MVC evaporator, but this is a clean stream due to the high purity of the BFW.
  • the evaporator produces a blow-down stream that is treated and disposed of.
  • MVC evaporators typically operate at concentration factors (CFs) of 20-40, meaning that the evaporator blowdown flowrate is only 2.5-5.0% that of the feed rate, but 20-40 times more concentrated, with TDS levels of 40,000-100,000 ppm.
  • the liquid that is circulated through the evaporator has the same high TDS levels. The high TDS levels raise the boiling point of the liquid in the evaporator, increasing the electrical load of the vapor compressor.
  • Figure 4 refers to an example of how superheated steam can be used to enhance the MVC/drum boiler system.
  • the drum boiler includes a superheater that adds heat to the saturated steam from the drum, producing superheated steam.
  • the MVC evaporator is operated at a considerably lower CF. This improves the performance of the evaporator, but necessitates a much higher blowdown flowrate. This less concentrated blowdown stream is boosted in pressure and contacted with the superheated steam in a contactor. The superheated steam vaporizes part of the blow-down, producing saturated SAGD steam and a more concentrated blow-down stream that resembles the evaporator blow-down stream in Figure 3.
  • the process in Figure 4 offers two advantages. Firstly it enables the evaporator to operate at lower CFs and consequently lower TDS levels, lowering the boiling point elevation and load of the compressor. Secondly, it allows more steam to be generated at relatively low marginal costs. The cost is additional CAPEX for the superheater, blow-down pump, and contactor, and additional OPEX for the incremental gas burned in the drum boiler. Table I shows water and steam flowrates for the two cases. For simplicity, normalized mass units are used.
  • the evaporator also produces 98.6 units of distillate, while the boiler also produces 96.6 units of saturated steam, which is converted to 96.6 units of superheated steam at 400°C and 96.4 bar(g).
  • the MVC evaporator is operated at a CF of only 6, resulting in a blow-down flowrate of 19.4 units. This blowdown is contacted with the 96.6 units of superheated steam to produced 112.5 units of saturated steam at 309°C and 96.4 bar(g) and 3.5 units of concentrated blowdown for disposal.
  • Steam tables show that there is sufficient enthalpy in 96.6 units of 400°C, 96.4 bar(g) superheated steam to vaporize 15.9 units of evaporator blowdown at 100°C.
  • Table I shows that the process in Figure 4 can deliver 112.5 units of SAGD steam, versus the 96.6 units in the reference case. This demonstrates that utilizing 400°C superheated steam can increase the steam output by 16%.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Fluid Mechanics (AREA)
  • Geochemistry & Mineralogy (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical & Material Sciences (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Abstract

L'invention porte sur une vapeur, qui est produite à l'aide d'une eau d'alimentation de chaudière à haute teneur totale en solides dissous (TDS), tout en maintenant des taux de vidange de chaudière relativement bas. Dans un premier mode de réalisation, une chaudière est apte à produire de la vapeur de basse qualité à partir de l'eau d'alimentation à haute TDS pour maintenir des conditions humides dans les tubes de chaudière afin d'atténuer des problèmes d'encrassage/entartrage. La vapeur de basse qualité est ensuite divisée en une fraction vapeur et un courant de vidange liquide. La fraction vapeur est surchauffée pour former une vapeur surchauffée. Le courant de vidange liquide est amené à échanger de la chaleur avec la vapeur surchauffée ainsi créée, pour vaporiser une partie de la vidange de façon à former une vapeur finie et un courant de déchets. Ceci réduit la vidange aux déchets et crée une plus grande quantité de vapeur pour l'utilisateur final. La vapeur finie est envoyée à son usage final, par exemple un processus de récupération thermique d'hydrocarbure. Les avantages comprennent un faible coût, un plus haut rendement et une faible complexité d'équipement.
PCT/US2014/033860 2013-04-11 2014-04-11 Production de vapeur à vidange réduite WO2014169245A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA2902612A CA2902612A1 (fr) 2013-04-11 2014-04-11 Production de vapeur a vidange reduite

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201361810779P 2013-04-11 2013-04-11
US61/810,779 2013-04-11
US14/251,278 2014-04-11
US14/251,278 US20140305645A1 (en) 2013-04-11 2014-04-11 Reduced blowdown steam generation

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WO2014169245A1 true WO2014169245A1 (fr) 2014-10-16

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Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015054773A1 (fr) * 2013-10-18 2015-04-23 Husky Oil Operations Limited Procédé de recyclage d'eau de purge et système pour augmenter des pourcentages de recyclage et de récupération d'eau pour des unités de génération de vapeur
CA2986916C (fr) * 2015-05-26 2023-10-17 XDI Holdings, LLC Systeme de generation directe de vapeur assistee par plasma, a l'eau sale, appareil et procede
US11022299B2 (en) * 2015-11-09 2021-06-01 Babcock & Wilcox Canada Corp. Multi-circulation heat recovery steam generator for enhanced oil recovery/steam assisted gravity drainage
US11415314B2 (en) * 2019-06-19 2022-08-16 The Babcock & Wilcox Company Natural circulation multi-circulation package boiler with superheat for steam assisted gravity drainage (SAGD) process including superheat

Citations (3)

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Publication number Priority date Publication date Assignee Title
US6655322B1 (en) * 2002-08-16 2003-12-02 Chemtreat, Inc. Boiler water blowdown control system
US20030226348A1 (en) * 2002-06-10 2003-12-11 Pelini Robert Gino System and method for producing injection-quality steam for combustion turbine power augmentation
US20080110630A1 (en) * 2003-11-26 2008-05-15 Minnich Keith R Method for Production of High Pressure Steam from Produced Water

Family Cites Families (5)

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Publication number Priority date Publication date Assignee Title
CA2414611C (fr) * 2002-12-17 2006-11-07 Stewart J. Wood Recuperation de chaleur par purge sous pression
US8166925B2 (en) * 2007-10-26 2012-05-01 Fccl Partnership Method and apparatus for steam generation
US8539750B2 (en) * 2010-04-30 2013-09-24 Siemens Energy, Inc. Energy recovery and steam supply for power augmentation in a combined cycle power generation system
US20120006671A1 (en) * 2010-07-07 2012-01-12 General Electric Company Control of scale formation in produced water evaporators
US9593563B2 (en) * 2011-10-05 2017-03-14 Statoil Petroleum As Method and apparatus for generating steam for the recovery of hydrocarbon

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030226348A1 (en) * 2002-06-10 2003-12-11 Pelini Robert Gino System and method for producing injection-quality steam for combustion turbine power augmentation
US6655322B1 (en) * 2002-08-16 2003-12-02 Chemtreat, Inc. Boiler water blowdown control system
US20080110630A1 (en) * 2003-11-26 2008-05-15 Minnich Keith R Method for Production of High Pressure Steam from Produced Water

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Publication number Publication date
CA2902612A1 (fr) 2014-10-16
US20140305645A1 (en) 2014-10-16

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