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{{short description|Device that removes dissolved gases from liquids}}
{{short description|Device that removes dissolved gases from liquids}}
[[File:Open deaerator plant.jpg|thumb|A deaerator plant]]
{{advert|date=September 2018}}A '''deaerator''' is a device that removes oxygen and other dissolved [[gas]]es from liquids and pumpable compounds. Deaerators are considered [[Water treatment]] equipment.


A '''deaerator''' is a device that is used for the removal of dissolved gases like oxygen from a liquid.
==History==


Thermal deaerators are commonly used to remove dissolved gases in [[feedwater]] for steam-generating [[boiler]]s. The deaerator is part of the feedwater heating system.<ref name="STEAM" /><ref name="Newterra" /> Dissolved [[oxygen]] in feedwater will cause serious corrosion damage in a boiler by attaching to the walls of metal piping and other equipment forming [[oxide]]s (like rust). Dissolved [[carbon dioxide]] combines with water to form [[carbonic acid]] that may cause further corrosion. Most deaerators are designed to remove oxygen down to levels of 7 [[parts per billion]] by weight or less, as well as essentially eliminating carbon dioxide.<ref name="Sterling" /><ref name="Stork" />
Manufacturing of deaerators started in the 1800s. Before 1867, deaerators were used as part of the ice manufacturing purification process. <ref>The Wichita Star, Wichita, KS, May 26, 1887. [https://www.newspapers.com/image/366114751/?terms=deaerator&match=1] Retrieved Apr 23, 2021</ref> Before 1881, feed water heaters were used for marine applications. <ref>Iowa County Democrat, Mineral Point, WI, Mar 4, 1881. [https://www.newspapers.com/image/679036172/?terms=contact%20feed%20heater&match=1] Retrieved Apr 23, 2021</ref>


Vacuum deaerators are used to remove dissolved gases from products such as food, personal care products, cosmetic products, chemicals, and pharmaceuticals to increase the dosing accuracy in the [[Aseptic processing|filling process]], to increase product shelf stability, to prevent oxidative effects (e.g. discolouration, changes of smell or taste, rancidity), to alter [[pH]], and to reduce packaging volume.<ref name="OSTI" />
Two sister ships Olympic and Titanic (1912) had contact feed heaters on board. <ref>Encyclopedia Titanic by Stephen Carey. [https://www.encyclopedia-titanica.org/cold-starting-the-titanic.html#_TOC_250003] Retrieved April 23, 2021</ref> In 1934 the US Navy purchased an atomizing deaerator. <ref>SAMCO, Aug 26, 2016. [https://www.samcotech.com/best-boiler-feedwater-treatment-equipment-supply-technology-companies/] Retrieved Apr 24, 2021</ref> During the 1920s the feedwater headers and deaerators designs improved. <ref>Montclair Times, Montclair, NJ, Dec 1, 1926. [https://www.newspapers.com/image/515359146/?terms=Cochrane%20Corporation&match=1] Retrieved Apr 23, 2021</ref> <ref>The News, Paterson, NJ, May 16, 1928. [https://www.newspapers.com/image/525441913/?terms=Cochrane%20Corporation&match=1] Retrieved Apr 23, 2021</ref> <ref>Vermont Tribune, Ludlow, Vermont, purifying feed water, Apr 13, 1900. [https://www.newspapers.com/image/490886001/?terms=Cole%20A%20Stickle&match=1] Retrieved April 23, 2021</ref> Deaerators continue to be used today for many applications.


Manufacturing of deaerators started in the 1800s and continues to the present day.{{cn|date=November 2023}}
==Earlier patents==
In 1899, George M Kleucker received a patent for an improved method of deaerating water. <ref>US Patent August 1899. [https://patents.google.com/patent/US664763A/en?inventor=George+M+Kleucker&before=priority:18991231&after=priority:18990101&oq=inventor:(George+M+Kleucker)+1899] Retrieved April 23, 2021</ref>


== History ==
1921 through 1933, George Gibson, Percy Lyon, and Victor Rohlin of Cochrane received deaerator / degasification patents for bubbling steam through liquid.<ref> Patent, Google.[https://patents.google.com/patent/US1914166A/en//] Retrieved Mar 18, 2023</ref><ref>Patent, Google.[https://patents.google.com/patent/US1596423A/en//] Retrieved Mar 18, 2023</ref><ref>Google, Patent.[https://patents.google.com/patent/US1877412A/en//] Retrieved Mar 18, 2023</ref>


Manufacturing of deaerators started in the 1800s.They were used to purify water used in the ice manufacturing process.<ref name="Wichita Star 26 May 1887" /> Feed water heaters were used for marine applications.<ref name="Iowa County Democrat 04 Mar 1881" /> In 1899, George M Kleucker received a patent for an improved method of de-aerating water.<ref name="US664763A" />
1926 Brown Stanley received a patent for reducing oxygen and nitrogen gases (deaeration).<ref>Patent, Google.[https://patents.google.com/patent/US1750035A/en//] Retrieved Mar 18, 2023</ref>


Two sister ships, Olympic and [[Titanic]] (1912), had contact feed heaters on board.<ref name="Carey" /> In 1934 the US Navy purchased an atomizing deaerator.<ref name="samcotech" />
1937 Samuel B Applebaum of Permutit received a water deaerator and purifier patent.<ref>Intellingencer Journal, Feb 13, 1958.[https://www.newspapers.com/image/558615820/?terms=Permutit%20deaerator&match=1//] Retrieved Mar 18, 2023</ref><ref>Patent Google.[https://patents.google.com/patent/US2204062A/en//] Retrieved Mar 18, 2023</ref>


During the 1920s the feedwater heaters and deaerators designs improved.<ref name="Montclair Times 01 Dec 1926" /><ref name="The News 16 May 1928" /><ref name="Vermont Tribune 13 Apr 1900" />
==Manufacturing pioneers==


Between 1921 and 1933, George Gibson, Percy Lyon, and Victor Rohlin of Cochrane received deaerator / degasification patents for bubbling steam through liquid.<ref name="US1914166A" /><ref name="US1596423A" /><ref name="US1877412A" />
Stickle, Cochrane, and Permutit are three of the oldest Deaerator manufacturers in the USA.<ref>Stickle History, [https://sticklesteam.com/history/] Retrieved April 23, 2021</ref> <ref>Handbook, Chapter 14 Degasification. http://ssu.ac.ir/cms/fileadmin/user_upload/Daneshkadaha/dbehdasht/markaz_tahghighat_olom_va_fanavarihaye_zist_mohiti/e_book/pasmand/water/58723_14.pdf] Retrieved April 23, 2021</ref> In 1929, a court case between Elliott Company (no longer in business) and H.S.B.W. Cochrane Corporation allowed both businesses to continue manufacturing deaerators.<ref>Court Case, 1929. [https://casetext.com/case/elliott-co-v-hsbw-cochrane-corporation] Retrieved April 23, 2021</ref>


1926 Brown Stanley received a patent for reducing oxygen and nitrogen gases (deaeration).<ref name="US1750035A" />
In 1909 Weir was manufacturing contact feed heaters (for de-aeratoring) in Europe.<ref>The Guardian, Nov 2, 1951.[https://www.newspapers.com/image/259444815/?terms=de-aerator&match=1//] Retrieved Mar 18, 2023</ref><ref>Daily Mail, Feb 9, 1925.[https://www.newspapers.com/image/794145452/?terms=contact%20feed%20heater&match=1//] Retrieved Mar 18, 2023</ref><ref>The Perthshire Advertiser, Feb 27, 1909.[https://www.newspapers.com/image/806520749/?terms=%22contact%20feed%20heater%22&match=1//] Retrieved Mar 18, 2023</ref>


In 1937 Samuel B Applebaum of Permutit received a water deaerator and purifier patent.<ref name="Intelligencer Journal 13 Feb 1958" /><ref name="US2204062A" />
By 1937 Permutit was manufacturing deaerators<ref>Intellingencer Journal, Feb 13, 1958.[https://www.newspapers.com/image/558615820/?terms=Permutit%20deaerator&match=1//] Retrieved Mar 18, 2023</ref><ref>Patent Google.[https://patents.google.com/patent/US2204062A/en//] Retrieved Mar 18, 2023</ref>
In 1939, manufacturers Cochrane, Darby, Elliott, Groeschel, Stearns-Rogers, Worthington, and others were competing against each other for business.<ref>The Alliance Times-Herald, Mar 31, 1939.[https://www.newspapers.com/image/669528207/?terms=Worthington%20deaerator&match=1//] Retrieved Mar 18, 2023</ref> In 1949 Chicago Heater was formed and became a leading deaerator manufacturer.<ref>Chicago Tribune, Jul 15, 1949.[https://www.newspapers.com/image/371805753/?terms=%22Chicago%20Heater%22&match=1//] Retrieved Mar 18, 2023</ref> In 1954, manufacturers Allis-Chalmers, Chicago Heater, Cochrane, Elliott, Graver, Swartwout, Worthington, and others were in business.<ref>News-Record, Aug 2, 1954.[https://www.newspapers.com/image/444861742/?terms=%22Chicago%20Heater%22&match=1//] Retrieved Mar 18, 2023</ref>


Deaerators continue to be used today for many applications.{{cn|date=November 2023}}
==Type Industries==


== Principles ==
Deaerators are used in many industries such as Co-generation Plants, Hospital Boiler Rooms, Larger Laundry Facilities, Marine, Oil Fields (such as steam injection), [[Oil refinery]], Off-Shore Platforms, [[Paper mill]]s, Power Plant, Prison Boiler Rooms, [[Steel mill]]s, and many other industries.


Oxygen and Nitrogen are two non-condensable gases that are removed by deaeration. [[Henry's law]] describes the relationship of dissolved gases and partial pressures. Thermal deaeration relies on the principle that the solubility of a gas in water decreases as the water temperature increases and approaches its [[boiling point]]. In the deaerator, water is heated up to close to its boiling point with a minimum pressure drop and minimum vent. Deaeration is done by spraying feedwater into a chamber to increase its surface area, and may involve flow over multiple layers of trays. This scrubbing (or stripping) steam is fed to the bottom of the deaeration section of the deaerator. When steam contacts the feedwater, it heats it up to its boiling point and dissolved gases are released from the feedwater and vented from the deaerator through the vent. The treated water falls into a storage tank below the deaerator.<ref name="boilersinfo.com" /><ref name="Sterling" />
==Types==


[[Oxygen scavenger|Oxygen scavenging]] chemicals are very often added to the deaerated boiler feedwater to remove any last traces of oxygen that were not removed by the deaerator. The type of chemical added depends on whether the location uses a volatile or non-volatile water treatment program. Most lower pressure systems (lower than {{convert|650|psi|abbr=on}}) use non-volatile treatment programs. The most commonly used oxygen scavenger for lower pressure systems is [[sodium sulfite]] (Na<sub>2</sub>SO<sub>3</sub>). It is very effective and rapidly reacts with traces of oxygen to form [[sodium sulfate]] (Na<sub>2</sub>SO<sub>4</sub>) which is non-scaling. Most higher pressure systems (higher than {{convert|650|psi|abbr=on}}) and all systems where certain highly alloyed materials are present are now using volatile programs, as many phosphate-based treatment programs are being phased out. Volatile programs are further broken down into oxidizing or reducing programs [(AVT(O) or AVT(R)] depending whether the environment requires an oxidizing or reducing environment to reduce the incidence of flow-accelerated corrosion. Flow-accelerated corrosion related failures have caused numerous accidents in which significant loss of property and life has occurred.{{citation needed|date=November 2019}} [[Hydrazine]] (N<sub>2</sub>H<sub>4</sub>) is an oxygen scavenger commonly used in volatile treatment programs. Other scavengers include [[carbohydrazide]], [[diethylhydroxylamine]], [[nitrilotriacetic acid]], [[ethylenediaminetetraacetic acid]], and [[hydroquinone]].
* The ''thermal deaerators'' {{sfn|Kent|1936|p=}}{{sfn|Babcock & Wilcox Co.|2005|p=}}{{sfn|Elliott|Chen|Swanekamp|1998|loc=Ch. 2|pp=167-}}
** The ''spray & tray-type'' (also called the ''cascade-type'') includes a vertical or horizontal domed [[wikt:deaeration|deaeration]] with a integral storage section, or as a separate section mounted on top of a horizontal cylindrical vessel which serves as the deaerated boiler feedwater storage tank.
** The ''spray-type'' consists only of a horizontal (or vertical) cylindrical vessel which serves as both the deaeration section, and a storage tank for boiler feedwater.
* The ''vacuum deaerators''
**Dynamic deaerator for medium to high viscous products
**Static deaerator for low viscous products
* The ''ultrasound deaerator for very viscous products''


=== Thermal deaerators ===
== Thermal deaerators ==
[[file:Deaerator-en.svg|thumb|Schematic diagram of a typical tray-type deaerator]]
[[File:Open deaerator plant.jpg|thumb|Deaerator plant]]Thermal deaerators are commonly used to remove dissolved gases in [[feedwater]] for steam-generating [[boiler]]s. Dissolved [[oxygen]] in feedwater will cause serious corrosion damage in a boiler by attaching to the walls of metal piping and other equipment and forming [[oxide]]s (like rust). Dissolved [[carbon dioxide]] combines with water to form [[carbonic acid]] that may cause further corrosion. Most deaerators are designed to remove oxygen down to levels of 7 [[Parts per billion|ppb]] by weight or less, as well as essentially eliminating carbon dioxide.<ref name="Sterling" /><ref name="Stork" /> The deaerators in the steam generating systems of most [[thermal power plant]]s use low pressure steam obtained from an extraction point in their [[steam turbine]] system. However, the steam generators in many large industrial facilities such as [[Oil refinery|petroleum refineries]] may use whatever low-pressure steam is available.
[[file:SprayDeaerator-en.svg|thumb|Schematic diagram of a typical spray-type deaerator]]


Thermal deaerators are commonly used to remove dissolved gases in [[feedwater]] for steam-generating [[boiler]]s. Dissolved [[oxygen]] in feedwater will cause serious corrosion damage in a boiler by attaching to the walls of metal piping and other equipment forming [[oxide]]s (like rust). Dissolved [[carbon dioxide]] combines with water to form [[carbonic acid]] that may cause further corrosion. Most deaerators are designed to remove oxygen down to levels of 7 [[parts per billion]] by weight or less, as well as essentially eliminating carbon dioxide.<ref name="Sterling" /><ref name="Stork" /> The deaerators in the steam generating systems of most [[thermal power plant]]s use low pressure steam obtained from an extraction point in their [[steam turbine]] system. However, the steam generators in many large industrial facilities such as [[Oil refinery|petroleum refineries]] may use whatever low-pressure steam is available.{{cn|date=November 2023}}
There are many different deaerators available from a number of manufacturers, and the actual construction details will vary from one manufacturer to another.


=== Tray-type ===
Figures 1 and 2 are representative schematic diagrams that depict each of the two major types of deaerators.


The tray-type deaerator has a vertical domed deaeration section mounted above a horizontal boiler feedwater storage vessel. Boiler feedwater enters the vertical deaeration section through spray valves above the perforated [[Theoretical plate|trays]] and then flows downward through the perforations. Low-pressure deaeration steam enters below the perforated trays and flows upward through the perforations. Combined action of spray valves & trays guarantees very high performance because of longer contact time between steam and water.<ref name="Heat Exchange Institute" />{{Verify source|date=November 2019}} Some designs use various types of [[packed bed]]s, rather than perforated trays, to provide good contact and mixing between the steam and the boiler feed water.{{cn|date=November 2023}}
===Spray and tray-type deaerator===
[[File:Deaerator-en.svg|thumb|391 px|right|Figure 1: A schematic diagram of a typical tray-type deaerator.]]


The steam strips the dissolved gas from the boiler feedwater and exits via the vent valve at the top of the domed section. If this vent valve has not be opened sufficiently, the deaerator will not work properly, resulting in feed water with a high oxygen content going to the boilers. Should the boiler not have an oxygen-content analyzer, a high level in the boiler chlorides may indicate the vent valve not being far enough open. Some designs may include a vent condenser to trap and recover any water [[Entrainment (engineering)|entrained]] in the vented gas. The vent line usually includes a valve and just enough steam is allowed to escape with the vented gases to provide a small visible telltale plume of steam.{{cn|date=November 2023}}
The typical spray & tray-type deaerator in Figure 1 has a vertical domed deaeration section mounted above a horizontal boiler feedwater storage vessel. Boiler feedwater enters the vertical deaeration section through spray valves above the perforated [[Theoretical plate|trays]] and then flows downward through the perforations. Low-pressure deaeration steam enters below the perforated trays and flows upward through the perforations. Combined action of spray valves & trays guarantees very high performance because of longer contact time between steam and water.<ref>{{cite book |title=Standards and Typical Specifications for Tray Type Deaerators |date=November 2016 |publisher=Heat Exchange Institute |edition=10th <!-- accessdate requires that you provide an url to the source accessdate=9 November 2019-->}}</ref>{{Verify source|date=November 2019}} Some designs use various types of [[packed bed]]s, rather than perforated trays, to provide good contact and mixing between the steam and the boiler feed water.


The deaerated water flows down into the horizontal storage vessel from where it is pumped to the steam generating boiler system. Low-pressure heating steam, which enters the horizontal vessel through a Sparge Pipe in the bottom of the vessel, is provided to keep the stored boiler feedwater warm. Stainless steel material is recommended for the sparger pipe.<ref name="Spirax Sarco" /> External [[Thermal insulation|insulation]] of the vessel is typically provided to minimize heat loss.
The steam strips the dissolved gas from the boiler feedwater and exits via the vent valve at the top of the domed section. This vent valve should not be opened sufficiently the deaerator will not work properly, causing high oxygen content in the feed water going to the boilers. Should the boiler not have an oxygen-content analyzer, a high level in the boiler chlorides may indicate the vent valve not being far enough open. Some designs may include a vent condenser to trap and recover any water [[Entrainment (engineering)|entrained]] in the vented gas. The vent line usually includes a valve and just enough steam is allowed to escape with the vented gases to provide a small visible telltale plume of steam.


=== Spray-type ===
The deaerated water flows down into the horizontal storage vessel from where it is pumped to the steam generating boiler system. Low-pressure heating steam, which enters the horizontal vessel through a Sparge Pipe in the bottom of the vessel, is provided to keep the stored boiler feedwater warm. Stainless steel material is recommended for the sparger pipe.<ref>Spirax Sarco, Jan 8, 2022. [https://www.spiraxsarco.com/learn-about-steam/the-boiler-house/the-feedtank-and-feedwater-conditioning] retrieved Jan 8, 2022</ref> External [[Thermal insulation|insulation]] of the vessel is typically provided to minimize heat loss.


The typical spray-type deaerator is a horizontal vessel which has a preheating section and a deaeration section. The two sections are separated by a baffle. Low-pressure steam enters the vessel through a sparger in the bottom of the vessel. The [[boiler feedwater]] is sprayed into section where it is preheated by the rising steam from the sparger. The purpose of the feedwater spray nozzle and the preheat section is to heat the boiler feedwater to its [[Boiling point#Saturation temperature and pressure|saturation temperature]] to facilitate stripping out the dissolved gases in the following deaeration section. The preheated feedwater then flows into the deaeration section (F), where it is deaerated by the steam rising from the sparger system. The gases stripped out of the water exit via the vent at the top of the vessel. Again, some designs may include a vent condenser to trap and recover any water entrained in the vented gas. Also again, the vent line usually includes a valve and just enough steam is allowed to escape with the vented gases to provide a small and visible telltale plume of steam. The deaerated boiler feedwater is pumped from the bottom of the vessel to the steam generating boiler system. Silencers (optional) have been used for reducing venting noise levels in the Deaerator equipment industry.{{cn|date=November 2023}}
====Spray-type deaerator====


== Vacuum deaerators ==
[[Image:SprayDeaerator-en.svg|thumb|287px|Figure 2: A schematic diagram of a typical spray-type deaerator.]]
[[File:Vacuum rotating disc deaerator.jpg|thumb|Schematic diagram of rotating disc deaerator]]


Deaerators are also used to remove dissolved gases from products such as food, personal care products, cosmetic products, chemicals, and pharmaceuticals to increase the dosing accuracy in the [[Aseptic processing|filling process]], to increase product shelf stability, to prevent oxidative effects (e.g. discolouration, changes of smell or taste, rancidity), to alter [[pH]], and to reduce packaging volume. Vacuum deaerators are also used in the petrochemical field. <ref name="OSTI" />
As shown in Figure 2, the typical spray-type deaerator is a horizontal vessel which has a preheating section (E) and a deaeration section (F). The two sections are separated by a baffle (C). Low-pressure steam enters the vessel through a sparger in the bottom of the vessel.


In 1921 a tank with vacuum pump for removing gases was used in Pittsburgh.<ref name="Public Opinion, Chambersburg, PA, Feb 11, 1921" /> In 1934 and 1940 a tank with vacuum pump for removing gases were used in Indiana.<ref name="Palladium-Item, Richmond, Indiana, Sep 24, 1934" /><ref name="Union City Times-Gazette, Jul 23, 1940" />
The [[boiler feedwater]] is sprayed into section (E) where it is preheated by the rising steam from the sparger. The purpose of the feedwater spray nozzle (A) and the preheat section is to heat the boiler feedwater to its [[Boiling point#Saturation temperature and pressure|saturation temperature]] to facilitate stripping out the dissolved gases in the following deaeration section.


Vacuum deaerators can be rubber lined on the inside to protect the steel heads and shell from corrosion.<ref name="Paterson Evening News, Paterson, NJ, Sep 12, 1956" />
The preheated feedwater then flows into the deaeration section (F), where it is deaerated by the steam rising from the sparger system. The gases stripped out of the water exit via the vent at the top of the vessel. Again, some designs may include a vent condenser to trap and recover any water entrained in the vented gas. Also again, the vent line usually includes a valve and just enough steam is allowed to escape with the vented gases to provide a small and visible telltale plume of steam.


=== Rotating Disc ===
The deaerated boiler feedwater is pumped from the bottom of the vessel to the steam generating boiler system.
In a typical design, the product is distributed as a thin layer on a high speed spinning disc via special feed system. The centrifugal force slings it through a perforated screen onto the inner wall of the vessel, which is under vacuum. Air (gas) pockets are released in the process and are drawn off by the vacuum. A discharge pump carries the deaerated product to the next process in the production line. For high viscous products the rotating disc is replaced with static one.{{cn|date=November 2023}}


== Other types ==
Silencers (optional) have been used for reducing venting noise levels in the Deaerator equipment industry.


Sound waves using ultrasonic equipment can be used to assist deaerating water.<ref name="STS Canada" /><ref name="Hielscher" />
=== Vacuum deaerator ===
Deaerators are also used to remove dissolved gases from products such as food, personal care products, cosmetic products, chemicals, and pharmaceuticals to increase the dosing accuracy in the [[Aseptic processing|filling process]], to increase product shelf stability, to prevent oxidative effects (e.g. discolouration, changes of smell or taste, rancidity), to alter [[pH]], and to reduce packaging volume. Vacuum deaerators are also used in the petrochemical field. <ref>OSTI abstract. [https://www.osti.gov/biblio/6160565] Retrieved April 23, 2021</ref>


== Production ==
In 1921 a tank with vacuum pump for removing gases was used in Pittsburgh.<ref>Public Opinion, Chambersburg, PA, Feb 11, 1921. [https://www.newspapers.com/image/449838854/?terms=vacuum%20deaerator&match=1//]
Retrieved Jan 25, 2022</ref> In 1934 and 1940 a tank with vacuum pump for removing gases were used in Indiana.<ref>Palladium-Item, Richmond, Indiana, Sep 24, 1934. [https://www.newspapers.com/image/248279794///] Retrieved Jan 25, 2022</ref> <ref>Union City Times-Gazette, Jul 23, 1940. [https://www.newspapers.com/image/654421299//] Retrieved Jan 25, 2022</ref>


Welding of the steel pressure vessels during the manufacturing process sometimes requires [[Post weld heat treatment]], XRAY, Dye Penetration, Ultrasonic, and other type non-destructive testing. [[ASME Boiler and Pressure Vessel Code]], [[NACE International]], and HEI (Heat Exchange Institute) have recommendations on the type of testing required.<ref name="woodhurdles" /> Older fabrication techniques also used cast iron for the shell and heads.<ref name="Vancouver Sun, Apr 14, 1962" />
Vacuum deaerators can be rubber lined on the inside to protect the steel heads and shell from corrosion.<ref>Paterson Evening News, Paterson, NJ, Sep 12, 1956.[https://www.newspapers.com/image/531573549/?terms=Deaerator%20cast%20iron&match=1//] Retrieved Jun 4, 2023</ref>


[[Thermal insulation]] is sometimes required after fabrication or after installation at the project site. Insulation is used to reduce heat loses.<ref name="Dept of Energy" />
====Dynamic deaerator====
As shown in Figure 3,<!-- Where is Figure 3? --> the product is distributed as a thin layer on a high speed spinning disc [3] via special feed system [1]. The centrifugal force slings it through a perforated screen onto the inner wall of the vessel, which is under vacuum . Air (gas) pockets are released in the process and are drawn off by the vacuum [4]. A discharge pump [2] carries the deaerated product to the next process in the production line. For high viscous products the rotating disc is replaced with static one.


== Inspection and maintenance ==
[[File:Vacuum rotating disc deaerator.jpg|thumb|right|Figure 3: A schematic diagram of rotating disc deaerator]]


NACE International (now known as Association for Materials Protection and Performance (AMPP)) and CIBO (Council of Industrial Boiler Owners) have several recommendations to increase the life of the deaerator unit. First, regular inspections (and testing) of the pressure vessel for cracking of welds, and repairing of any weld defects. Second, maintaining a proper water chemistry to reduce deaerator deterioration. Third, minimize temperature and pressure fluctuation. Fourth, internals and accessories should be inspected for proper operation. <ref name="AMPP" /><ref name="National Board" /><ref name="CIBO" /> NACE had created a Corrosion Task Group in 1984 that studied causes of corrosion and provided recommendations;<ref name="Jonas" /> NACE still provides recommendations to improve operations of the equipment.
===Ultrasound deaerator===
Sound waves using ultrasonic equipment can be used to assist deaerating water.<ref>STS Canada.[https://www.stscanadainc.com/ultrasonic-deaerator.html//] Retrieved Mar 18, 2023</ref><ref>Hielscher.[https://www.hielscher.com/highly-efficient-de-aeration-of-liquids-using-ultrasonics.htm//] Retrieved Mar 18, 2023</ref>


== Manufacturers ==
==Principles of operation==
Oxygen and Nitrogen are two non-condensable gases that are removed by deaeration. [[Henry's law]] describes the relationship of dissolved gases and partial pressures. Thermal deaeration relies on the principle that the solubility of a gas in water decreases as the water temperature increases and approaches its [[boiling point]]. In the deaerator, water is heated up to close to its boiling point with a minimum pressure drop and minimum vent. Deaeration is done by spraying feedwater into a chamber to increase its surface area, and may involve flow over multiple layers of trays. This scrubbing (or stripping) steam is fed to the bottom of the deaeration section of the deaerator. When steam contacts the feedwater, it heats it up to its boiling point and dissolved gases are released from the feedwater and vented from the deaerator through the vent. The treated water falls into a storage tank below the deaerator.<ref name="boilersinfo.com" /><ref name="Sterling" />


Stickle, Cochrane, and Permutit are three of the oldest Deaerator manufacturers in the USA.<ref name="Stickle" /><ref name="ssu" /> In 1929, a court case between Elliott Company (no longer in business) and H.S.B.W. Cochrane Corporation allowed both businesses to continue manufacturing deaerators.<ref name="Court Case, 1929" />
===Oxygen scavenging===
[[Oxygen scavenger|Oxygen scavenging]] chemicals are very often added to the deaerated boiler feedwater to remove any last traces of oxygen that were not removed by the deaerator. The type of chemical added depends on whether the location uses a volatile or non-volatile water treatment program.


In 1909 Weir was manufacturing contact feed heaters (for de-aerating) in Europe.<ref name="The Guardian, Nov 2, 1951" /><ref name="Daily Mail, Feb 9, 1925" /><ref name="thshire Advertiser, Feb 27, 190" />
Most lower pressure systems (lower than {{convert|650|psi|abbr=on}}) use non-volatile treatment programs. The most commonly used oxygen scavenger for lower pressure systems is [[sodium sulfite]] (Na<sub>2</sub>SO<sub>3</sub>). It is very effective and rapidly reacts with traces of oxygen to form [[sodium sulfate]] (Na<sub>2</sub>SO<sub>4</sub>) which is non-scaling.


By 1937 Permutit was manufacturing deaerators.<ref name="Intellingencer Journal, Feb 13, 1958" /><ref name="US2204062A" />
Most higher pressure systems (higher than {{convert|650|psi|abbr=on}}) and all systems where certain highly alloyed materials are present are now using volatile programs, as many phosphate-based treatment programs are being phased out. Volatile programs are further broken down into oxidizing or reducing programs [(AVT(O) or AVT(R)] depending whether the environment requires an oxidizing or reducing environment to reduce the incidence of flow-accelerated corrosion. Flow-accelerated corrosion related failures have caused numerous accidents in which significant loss of property and life has occurred.{{citation needed|date=November 2019}} [[Hydrazine]] (N<sub>2</sub>H<sub>4</sub>) is an oxygen scavenger commonly used in volatile treatment programs.


In 1939, Cochrane, Darby, Elliott, Groeschel, Stearns-Rogers, Worthington, and others were competing against each other for business.<ref name="Alliance Times-Herald, Mar 31, 1939" /> In 1949 Chicago Heater was formed and became a leading deaerator manufacturer.<ref name="Chicago Tribune, Jul 15, 1949" /> In 1954, Allis-Chalmers, Chicago Heater, Cochrane, Elliott, Graver, Swartwout, Worthington, and others were in business.<ref name="News-Record, Aug 2, 1954" />
Other scavengers include [[carbohydrazide]], [[diethylhydroxylamine]], [[nitrilotriacetic acid]], [[ethylenediaminetetraacetic acid]], and [[hydroquinone]].


== Applications ==
===Inspection and maintenance===


Deaerators are used in many industries such as co-generation plants, hospitals, larger laundry facilities, oil fields, [[oil refineries]], off-shore platforms, [[paper mill]]s, power plants, prisons, [[steel mill]]s, and many other industries.{{cn|date=September 2023}}
NACE International (now known as Association for Materials Protection and Performance (AMPP)) and CIBO (Council of Industrial Boiler Owners) have several recommendations to increase the life of the deaerator unit. First, regular inspections (and testing) of the pressure vessel for cracking of welds, and repairing of any weld defects. Second, maintaining a proper water chemistry to reduce deaerator deterioration. Third, minimize temperature and pressure fluctuation. Fourth, internals and accessories should be inspected for proper operation. <ref>AMPP, NACE RFP050-96, Standard Recommended Practice. [https://www.ampp.org//] Retrieved April 22, 2021</ref> <ref>The National Board of Boiler and Pressure Vessel Inspectors, April 1988. [https://www.nationalboard.org/PrintPage.aspx?pageID=180] Retrieved April 22, 2021</ref><ref>US Dept of Energy, CIBO paper dated Nov 1997. [https://www.energy.gov/sites/prod/files/2014/05/f15/steamhandbook.pdf] Retrieved April 23, 2021</ref> NACE had created a Corrosion Task Group in 1984 that studied causes of corrosion and provided recommendations;<ref>Proceedings of the American Power Conference paper, Otakar Jonas. [https://www.steamcycle.com/deaerator_corrosion.pdf] Retrieved Jun 3, 2022</ref> NACE still provides recommendations to improve operations of the equipment.


==Accessories==
== See also ==
* {{annotated link|Defoamer}}
Deaerator accessories include vent valve, inlet pump(s), water inlet valve, overflow valve or trap, (safety) relief valve, vacuum breaker, steam pressure reducing valve, level instrument, temperature instrument, and discharge pump(s). Vacuum deaerator will also require [[Vacuum pump]](s) and/or [[Vacuum ejector]](s)/eductor(s).
* {{annotated link|Degasification}}


== References ==
==Fabrication of deaerator==
Welding of the steel pressure vessels during the manufacturing process sometimes requires [[Post weld heat treatment]], XRAY, Dye Penetration, Ultrasonic, and other type non-destructive testing. [[ASME Boiler and Pressure Vessel Code]], [[NACE International]], and HEI (Heat Exchange Institute) have recommendations on the type of testing required. <ref>Deaerator history. [http://www.woodhurdles.com/M/d.html] Retrieved Apr 24, 2021</ref> Older fabrication techniques also used cast iron for the shell and heads.<ref>Vancouver Sun, Apr 14, 1962.[https://www.newspapers.com/image/492402132/?terms=Deaerator&match=1//] Retrieved Jun 4, 2023</ref>

==Insulation==
[[Thermal insulation]] is sometimes required after fabrication or after installation at the project site. Insulation is used to reduce heat loses.<ref>US Dept of Energy, Deaerators in Industrial Steam Systems.[https://www.energy.gov/sites/prod/files/2014/05/f16/steam18_steam_systems.pdf//] Retrieved Mar 18, 2023</ref>

==See also==
* [[Air preheater]]
* [[Defoamer]]
* [[Degasification]]
* [[Economizer]]
* [[Feedwater heater]]
* [[Fossil fuel power plant]]
* [[Industrial water treatment]]
* [[Thermal power station]]
* [[Water treatment]]

==References==
===Citations===
{{reflist|refs=


{{Reflist|refs=
<ref name="Sterling">{{cite web| url=http://www.sterlingdeaerator.com/principle.htm| title=The Deaerating Principle| publisher=Sterling Deaerator Company}}</ref>
<ref name="Sterling">{{cite web| url=http://www.sterlingdeaerator.com/principle.htm| title=The Deaerating Principle| publisher=Sterling Deaerator Company}}</ref>

<ref name="Stork">{{cite web| url=https://www.stork.com/en/products-services/power-services-products/stork-thermeq/deaerators| title=Deaerators| publisher=Stork| access-date=2016-09-30| archive-url=https://web.archive.org/web/20180901123425/https://www.stork.com/en/products-services/power-services-products/stork-thermeq/deaerators| archive-date=2018-09-01| url-status=dead}}</ref>
<ref name="Stork">{{cite web| url=https://www.stork.com/en/products-services/power-services-products/stork-thermeq/deaerators| title=Deaerators| publisher=Stork| access-date=2016-09-30| archive-url=https://web.archive.org/web/20180901123425/https://www.stork.com/en/products-services/power-services-products/stork-thermeq/deaerators| archive-date=2018-09-01| url-status=dead}}</ref>

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<ref name="boilersinfo.com">{{cite web|url=https://boilersinfo.com/deaerator-working-principle/|title=Deaerator working principle|publisher=Boilers Info}}</ref>
<ref name="boilersinfo.com">{{cite web|url=https://boilersinfo.com/deaerator-working-principle/|title=Deaerator working principle|publisher=Boilers Info}}</ref>
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<ref name="Newterra">{{Cite web |date=2023-01-05 |title=Water Treatment Deaerators |url=https://www.newterra.com/technologies/deaerator/|access-date=2023-08-17 | publisher = Newterra |language=en-US}}</ref>
<ref name="Wichita Star 26 May 1887">{{Cite web |title=The Wichita Star 26 May 1887, page 1 |url=https://www.newspapers.com/image/366114751/ |access-date=2023-08-17 |website=Newspapers.com |language=en}}</ref>
<ref name="Iowa County Democrat 04 Mar 1881">{{Cite web |title=Iowa County Democrat 04 Mar 1881, page 2 |url=https://www.newspapers.com/image/679036172/ |access-date=2023-08-17 |website=Newspapers.com |language=en}}</ref>
<ref name="US664763A">{{Cite patent|number=US664763A|title=Method of deaerating water|gdate=1900-12-25|invent1=Kleucker|inventor1-first=George M.|url=https://patents.google.com/patent/US664763A/en?inventor=George+M+Kleucker&before=priority:18991231&after=priority:18990101&oq=inventor:(George+M+Kleucker)+1899}}</ref>
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<ref name="samcotech">{{Cite web |last=D |first=Ryan |date=2016-08-26 |title=10 of the Best Boiler Feed Water Treatment Equipment Supply and Technology Companies |url=https://samcotech.com/best-boiler-feedwater-treatment-equipment-supply-technology-companies/ |access-date=2023-08-17 |website=SAMCO Technologies |language=en-US}}</ref>
<ref name="Montclair Times 01 Dec 1926">{{Cite web |title=Montclair Times 01 Dec 1926, page 14 |url=https://www.newspapers.com/image/515359146/ |access-date=2023-08-17 |website=Newspapers.com |language=en}}</ref>
<ref name="The News 16 May 1928">{{Cite web |title=The News 16 May 1928, page 7 |url=https://www.newspapers.com/image/525441913/ |access-date=2023-08-17 |website=Newspapers.com |language=en}}</ref>
<ref name="Vermont Tribune 13 Apr 1900">{{Cite web |title=Vermont Tribune 13 Apr 1900, page 1 |url=https://www.newspapers.com/image/490886001/ |access-date=2023-08-17 |website=Newspapers.com |language=en}}</ref>
<ref name="US1914166A">{{Cite patent|number=US1914166A|title=Apparatus for treating liquids|gdate=1933-06-13|invent1=Rohlin|inventor1-first=Victor A.|url=https://patents.google.com/patent/US1914166A/en/}}</ref>
<ref name="US1596423A">{{Cite patent|number=US1596423A|title=Water-deaerating apparatus|gdate=1926-08-17|invent1=Gibson|inventor1-first=George H.|url=https://patents.google.com/patent/US1596423A/en/}}</ref>
<ref name="US1877412A">{{Cite patent|number=US1877412A|title=Deaerating water heater|gdate=1932-09-13|invent1=Lyon|inventor1-first=Percy S.|url=https://patents.google.com/patent/US1877412A/en/}}</ref>
<ref name="US1750035A">{{Cite patent|number=US1750035A|title=Deaerator|gdate=1930-03-11|invent1=Stanley|inventor1-first=Brown|url=https://patents.google.com/patent/US1750035A/en/}}</ref>
<ref name="Intelligencer Journal 13 Feb 1958">{{Cite web |title=Intelligencer Journal 13 Feb 1958, page 42 |url=https://www.newspapers.com/image/558615820/ |access-date=2023-08-17 |website=Newspapers.com |language=en}}</ref>
<ref name="US2204062A">{{Cite patent|number=US2204062A|title=Water deaerator and purifier|gdate=1940-06-11|invent1=Applebaum|inventor1-first=Samuel B.|url=https://patents.google.com/patent/US2204062A/en/}}</ref>
<ref name="Heat Exchange Institute">{{cite book |title=Standards and Typical Specifications for Tray Type Deaerators |date=November 2016 |publisher=Heat Exchange Institute |edition=10th }}</ref>
<ref name="Spirax Sarco">{{Cite web|url=https://www.spiraxsarco.com/learn-about-steam/the-boiler-house/the-feedtank-and-feedwater-conditioning|title=The Feedtank and Feedwater Conditioning | publisher = Spirax Sarco }}</ref>
<ref name="OSTI">[https://www.osti.gov/biblio/6160565 OSTI abstract. Retrieved April 23, 2021]</ref>
<ref name="Public Opinion, Chambersburg, PA, Feb 11, 1921">[https://www.newspapers.com/image/449838854/ Public Opinion, Chambersburg, PA, Feb 11, 1921. Retrieved Jan 25, 2022]</ref>
<ref name="Palladium-Item, Richmond, Indiana, Sep 24, 1934">[https://www.newspapers.com/image/248279794/ Palladium-Item, Richmond, Indiana, Sep 24, 1934. Retrieved Jan 25, 2022]</ref>
<ref name="Union City Times-Gazette, Jul 23, 1940">[https://www.newspapers.com/image/654421299/ Union City Times-Gazette, Jul 23, 1940. Retrieved Jan 25, 2022]</ref>
<ref name="Paterson Evening News, Paterson, NJ, Sep 12, 1956">[https://www.newspapers.com/image/531573549/ Paterson Evening News, Paterson, NJ, Sep 12, 1956.Retrieved Jun 4, 2023]</ref>
<ref name="STS Canada">[https://www.stscanadainc.com/ultrasonic-deaerator.html/ STS Canada. Retrieved Mar 18, 2023]</ref>
<ref name="Hielscher">[https://www.hielscher.com/highly-efficient-de-aeration-of-liquids-using-ultrasonics.htm/ Hielscher. Retrieved Mar 18, 2023]</ref>
<ref name="woodhurdles">[http://www.woodhurdles.com/M/d.html Deaerator history. Retrieved Apr 24, 2021]</ref>
<ref name="Vancouver Sun, Apr 14, 1962">[https://www.newspapers.com/image/492402132/ Vancouver Sun, Apr 14, 1962. Retrieved Jun 4, 2023]</ref>
<ref name="Dept of Energy">[https://www.energy.gov/sites/prod/files/2014/05/f16/steam18_steam_systems.pdf US Dept of Energy, Deaerators in Industrial Steam Systems. Retrieved Mar 18, 2023]</ref>
<ref name="AMPP">[https://www.ampp.org/ AMPP, NACE RFP050-96, Standard Recommended Practice. Retrieved April 22, 2021]</ref>
<ref name="National Board">[https://www.nationalboard.org/PrintPage.aspx?pageID=180 The National Board of Boiler and Pressure Vessel Inspectors, April 1988. Retrieved April 22, 2021]</ref>
<ref name="CIBO">[https://www.energy.gov/sites/prod/files/2014/05/f15/steamhandbook.pdf US Dept of Energy, CIBO paper dated Nov 1997. Retrieved April 23, 2021]</ref>
<ref name="Jonas">[https://www.steamcycle.com/deaerator_corrosion.pdf Proceedings of the American Power Conference paper, Otakar Jonas. Retrieved Jun 3, 2022]</ref>
<ref name="Stickle">[https://sticklesteam.com/history/ Stickle History, Retrieved April 23, 2021]</ref>
<ref name="ssu">[http://ssu.ac.ir/cms/fileadmin/user_upload/Daneshkadaha/dbehdasht/markaz_tahghighat_olom_va_fanavarihaye_zist_mohiti/e_book/pasmand/water/58723_14.pdf Handbook, Chapter 14 Degasification. Retrieved April 23, 2021]</ref>
<ref name="Court Case, 1929">[https://casetext.com/case/elliott-co-v-hsbw-cochrane-corporation Court Case, 1929. Retrieved April 23, 2021]</ref>
<ref name="The Guardian, Nov 2, 1951">[https://www.newspapers.com/image/259444815/ The Guardian, Nov 2, 1951. Retrieved Mar 18, 2023]</ref>
<ref name="Daily Mail, Feb 9, 1925">[https://www.newspapers.com/image/794145452 Daily Mail, Feb 9, 1925. Retrieved Mar 18, 2023]</ref>
<ref name="thshire Advertiser, Feb 27, 190">[https://www.newspapers.com/image/806520749/ Perthshire Advertiser, Feb 27, 1909. Retrieved Mar 18, 2023]</ref>
<ref name="Intellingencer Journal, Feb 13, 1958">[https://www.newspapers.com/image/558615820/ Intellingencer Journal, Feb 13, 1958. Retrieved Mar 18, 2023]</ref>
<ref name="Alliance Times-Herald, Mar 31, 1939">[https://www.newspapers.com/image/669528207/ Alliance Times-Herald, Mar 31, 1939. Retrieved Mar 18, 2023]</ref>
<ref name="Chicago Tribune, Jul 15, 1949">[https://www.newspapers.com/image/371805753/ Chicago Tribune, Jul 15, 1949. Retrieved Mar 18, 2023]</ref>
<ref name="News-Record, Aug 2, 1954">[https://www.newspapers.com/image/444861742/ News-Record, Aug 2, 1954. Retrieved Mar 18, 2023]</ref>
}}
}}


===Sources===
== Sources ==

{{refbegin}}
{{refbegin}}
*{{cite book|author=Babcock & Wilcox Co.|title=Steam: Its Generation and Use|edition=41st|year=2005|isbn=0-9634570-0-4}}
* {{cite book|author=Babcock & Wilcox Co.|title=Steam: Its Generation and Use|edition=41st|year=2005|isbn=0-9634570-0-4}}
*{{cite book|last1=Elliott|first1=Thomas C. |last2=Chen|first2=Kao |last3=Swanekamp|first3=Robert |title=Standard Handbook of Powerplant Engineering|url=https://books.google.com/books?id=qYxUAAAAMAAJ|year=1998|publisher=McGraw-Hill |isbn=978-0-07-019435-9|edition=2nd}}
* {{cite book|last1=Elliott|first1=Thomas C. |last2=Chen|first2=Kao |last3=Swanekamp|first3=Robert |title=Standard Handbook of Powerplant Engineering|url=https://books.google.com/books?id=qYxUAAAAMAAJ|year=1998|publisher=McGraw-Hill |isbn=978-0-07-019435-9|edition=2nd}}
*{{cite book|editor-link=Robert Thurston Kent|editor-first=Robert Thurston |editor-last=Kent|title=Kents' Mechanical Engineers' Handbook in two volumes|edition=11th |publisher=John Wiley & Sons |year=1936}}
* {{cite book|editor-link=Robert Thurston Kent|editor-first=Robert Thurston |editor-last=Kent|title=Kents' Mechanical Engineers' Handbook in two volumes|edition=11th |publisher=John Wiley & Sons |year=1936}}

{{refend}}
{{refend}}


==Additional reading==
== Further reading ==
* Betz Handbook of Industrial Water Conditioning, Chapter 9 boiler feedwater deaeration. 8th Edition, copyright 1980, LOC 79-56368.

* NEA (National Environmental Agency) Paper, "Energy Best Practice Guide for Oil Refining
Betz Handbook of Industrial Water Conditioning, Chapter 9 boiler feedwater deaeration. 8th Edition, copyright 1980, LOC 79-56368.

National Board "System Design, Specifications, Operation, and Inspection of Deaerators" April 1988. https://www.nationalboard.org/index.aspx?pageID=164&ID=180

NEA (National Environmental Agency) Paper, "Energy Best Practice Guide for Oil Refining,
Petrochemical and Chemical Plants", June 2021. https://www.nea.gov.sg/docs/default-source/our-services/energy-efficiency/best-practice-guide-for-heating-systems.pdf

US Dept of Energy, Deaerators in Industrial Steam Systems. https://www.energy.gov/sites/prod/files/2014/05/f16/steam18_steam_systems.pdf


==External links==
== External links ==
*[http://www.awt.org Association of Water Technologies]
* [http://www.awt.org Association of Water Technologies]
*[https://www.deaerator.it/deaerator/ Deaerator design]
* [https://www.deaerator.it/deaerator/ Deaerator design]
* [https://www.nea.gov.sg/docs/default-source/our-services/energy-efficiency/best-practice-guide-for-heating-systems.pdf Petrochemical and Chemical Plants", June 2021]
*[[Post weld heat treatment]]
* [https://www.energy.gov/sites/prod/files/2014/05/f16/steam18_steam_systems.pdf US Dept of Energy, Deaerators in Industrial Steam Systems]
* [https://www.nationalboard.org/index.aspx?pageID=164&ID=180 National Board "System Design, Specifications, Operation, and Inspection of Deaerators" April 1988]


[[Category:Power station technology]]
[[Category:Power station technology]]

Latest revision as of 18:08, 5 November 2023

A deaerator plant

A deaerator is a device that is used for the removal of dissolved gases like oxygen from a liquid.

Thermal deaerators are commonly used to remove dissolved gases in feedwater for steam-generating boilers. The deaerator is part of the feedwater heating system.[1][2] Dissolved oxygen in feedwater will cause serious corrosion damage in a boiler by attaching to the walls of metal piping and other equipment forming oxides (like rust). Dissolved carbon dioxide combines with water to form carbonic acid that may cause further corrosion. Most deaerators are designed to remove oxygen down to levels of 7 parts per billion by weight or less, as well as essentially eliminating carbon dioxide.[3][4]

Vacuum deaerators are used to remove dissolved gases from products such as food, personal care products, cosmetic products, chemicals, and pharmaceuticals to increase the dosing accuracy in the filling process, to increase product shelf stability, to prevent oxidative effects (e.g. discolouration, changes of smell or taste, rancidity), to alter pH, and to reduce packaging volume.[5]

Manufacturing of deaerators started in the 1800s and continues to the present day.[citation needed]

History

[edit]

Manufacturing of deaerators started in the 1800s.They were used to purify water used in the ice manufacturing process.[6] Feed water heaters were used for marine applications.[7] In 1899, George M Kleucker received a patent for an improved method of de-aerating water.[8]

Two sister ships, Olympic and Titanic (1912), had contact feed heaters on board.[9] In 1934 the US Navy purchased an atomizing deaerator.[10]

During the 1920s the feedwater heaters and deaerators designs improved.[11][12][13]

Between 1921 and 1933, George Gibson, Percy Lyon, and Victor Rohlin of Cochrane received deaerator / degasification patents for bubbling steam through liquid.[14][15][16]

1926 Brown Stanley received a patent for reducing oxygen and nitrogen gases (deaeration).[17]

In 1937 Samuel B Applebaum of Permutit received a water deaerator and purifier patent.[18][19]

Deaerators continue to be used today for many applications.[citation needed]

Principles

[edit]

Oxygen and Nitrogen are two non-condensable gases that are removed by deaeration. Henry's law describes the relationship of dissolved gases and partial pressures. Thermal deaeration relies on the principle that the solubility of a gas in water decreases as the water temperature increases and approaches its boiling point. In the deaerator, water is heated up to close to its boiling point with a minimum pressure drop and minimum vent. Deaeration is done by spraying feedwater into a chamber to increase its surface area, and may involve flow over multiple layers of trays. This scrubbing (or stripping) steam is fed to the bottom of the deaeration section of the deaerator. When steam contacts the feedwater, it heats it up to its boiling point and dissolved gases are released from the feedwater and vented from the deaerator through the vent. The treated water falls into a storage tank below the deaerator.[20][3]

Oxygen scavenging chemicals are very often added to the deaerated boiler feedwater to remove any last traces of oxygen that were not removed by the deaerator. The type of chemical added depends on whether the location uses a volatile or non-volatile water treatment program. Most lower pressure systems (lower than 650 psi (4,500 kPa)) use non-volatile treatment programs. The most commonly used oxygen scavenger for lower pressure systems is sodium sulfite (Na2SO3). It is very effective and rapidly reacts with traces of oxygen to form sodium sulfate (Na2SO4) which is non-scaling. Most higher pressure systems (higher than 650 psi (4,500 kPa)) and all systems where certain highly alloyed materials are present are now using volatile programs, as many phosphate-based treatment programs are being phased out. Volatile programs are further broken down into oxidizing or reducing programs [(AVT(O) or AVT(R)] depending whether the environment requires an oxidizing or reducing environment to reduce the incidence of flow-accelerated corrosion. Flow-accelerated corrosion related failures have caused numerous accidents in which significant loss of property and life has occurred.[citation needed] Hydrazine (N2H4) is an oxygen scavenger commonly used in volatile treatment programs. Other scavengers include carbohydrazide, diethylhydroxylamine, nitrilotriacetic acid, ethylenediaminetetraacetic acid, and hydroquinone.

Thermal deaerators

[edit]
Schematic diagram of a typical tray-type deaerator
Schematic diagram of a typical spray-type deaerator

Thermal deaerators are commonly used to remove dissolved gases in feedwater for steam-generating boilers. Dissolved oxygen in feedwater will cause serious corrosion damage in a boiler by attaching to the walls of metal piping and other equipment forming oxides (like rust). Dissolved carbon dioxide combines with water to form carbonic acid that may cause further corrosion. Most deaerators are designed to remove oxygen down to levels of 7 parts per billion by weight or less, as well as essentially eliminating carbon dioxide.[3][4] The deaerators in the steam generating systems of most thermal power plants use low pressure steam obtained from an extraction point in their steam turbine system. However, the steam generators in many large industrial facilities such as petroleum refineries may use whatever low-pressure steam is available.[citation needed]

Tray-type

[edit]

The tray-type deaerator has a vertical domed deaeration section mounted above a horizontal boiler feedwater storage vessel. Boiler feedwater enters the vertical deaeration section through spray valves above the perforated trays and then flows downward through the perforations. Low-pressure deaeration steam enters below the perforated trays and flows upward through the perforations. Combined action of spray valves & trays guarantees very high performance because of longer contact time between steam and water.[21][verification needed] Some designs use various types of packed beds, rather than perforated trays, to provide good contact and mixing between the steam and the boiler feed water.[citation needed]

The steam strips the dissolved gas from the boiler feedwater and exits via the vent valve at the top of the domed section. If this vent valve has not be opened sufficiently, the deaerator will not work properly, resulting in feed water with a high oxygen content going to the boilers. Should the boiler not have an oxygen-content analyzer, a high level in the boiler chlorides may indicate the vent valve not being far enough open. Some designs may include a vent condenser to trap and recover any water entrained in the vented gas. The vent line usually includes a valve and just enough steam is allowed to escape with the vented gases to provide a small visible telltale plume of steam.[citation needed]

The deaerated water flows down into the horizontal storage vessel from where it is pumped to the steam generating boiler system. Low-pressure heating steam, which enters the horizontal vessel through a Sparge Pipe in the bottom of the vessel, is provided to keep the stored boiler feedwater warm. Stainless steel material is recommended for the sparger pipe.[22] External insulation of the vessel is typically provided to minimize heat loss.

Spray-type

[edit]

The typical spray-type deaerator is a horizontal vessel which has a preheating section and a deaeration section. The two sections are separated by a baffle. Low-pressure steam enters the vessel through a sparger in the bottom of the vessel. The boiler feedwater is sprayed into section where it is preheated by the rising steam from the sparger. The purpose of the feedwater spray nozzle and the preheat section is to heat the boiler feedwater to its saturation temperature to facilitate stripping out the dissolved gases in the following deaeration section. The preheated feedwater then flows into the deaeration section (F), where it is deaerated by the steam rising from the sparger system. The gases stripped out of the water exit via the vent at the top of the vessel. Again, some designs may include a vent condenser to trap and recover any water entrained in the vented gas. Also again, the vent line usually includes a valve and just enough steam is allowed to escape with the vented gases to provide a small and visible telltale plume of steam. The deaerated boiler feedwater is pumped from the bottom of the vessel to the steam generating boiler system. Silencers (optional) have been used for reducing venting noise levels in the Deaerator equipment industry.[citation needed]

Vacuum deaerators

[edit]
Schematic diagram of rotating disc deaerator

Deaerators are also used to remove dissolved gases from products such as food, personal care products, cosmetic products, chemicals, and pharmaceuticals to increase the dosing accuracy in the filling process, to increase product shelf stability, to prevent oxidative effects (e.g. discolouration, changes of smell or taste, rancidity), to alter pH, and to reduce packaging volume. Vacuum deaerators are also used in the petrochemical field. [5]

In 1921 a tank with vacuum pump for removing gases was used in Pittsburgh.[23] In 1934 and 1940 a tank with vacuum pump for removing gases were used in Indiana.[24][25]

Vacuum deaerators can be rubber lined on the inside to protect the steel heads and shell from corrosion.[26]

Rotating Disc

[edit]

In a typical design, the product is distributed as a thin layer on a high speed spinning disc via special feed system. The centrifugal force slings it through a perforated screen onto the inner wall of the vessel, which is under vacuum. Air (gas) pockets are released in the process and are drawn off by the vacuum. A discharge pump carries the deaerated product to the next process in the production line. For high viscous products the rotating disc is replaced with static one.[citation needed]

Other types

[edit]

Sound waves using ultrasonic equipment can be used to assist deaerating water.[27][28]

Production

[edit]

Welding of the steel pressure vessels during the manufacturing process sometimes requires Post weld heat treatment, XRAY, Dye Penetration, Ultrasonic, and other type non-destructive testing. ASME Boiler and Pressure Vessel Code, NACE International, and HEI (Heat Exchange Institute) have recommendations on the type of testing required.[29] Older fabrication techniques also used cast iron for the shell and heads.[30]

Thermal insulation is sometimes required after fabrication or after installation at the project site. Insulation is used to reduce heat loses.[31]

Inspection and maintenance

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NACE International (now known as Association for Materials Protection and Performance (AMPP)) and CIBO (Council of Industrial Boiler Owners) have several recommendations to increase the life of the deaerator unit. First, regular inspections (and testing) of the pressure vessel for cracking of welds, and repairing of any weld defects. Second, maintaining a proper water chemistry to reduce deaerator deterioration. Third, minimize temperature and pressure fluctuation. Fourth, internals and accessories should be inspected for proper operation. [32][33][34] NACE had created a Corrosion Task Group in 1984 that studied causes of corrosion and provided recommendations;[35] NACE still provides recommendations to improve operations of the equipment.

Manufacturers

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Stickle, Cochrane, and Permutit are three of the oldest Deaerator manufacturers in the USA.[36][37] In 1929, a court case between Elliott Company (no longer in business) and H.S.B.W. Cochrane Corporation allowed both businesses to continue manufacturing deaerators.[38]

In 1909 Weir was manufacturing contact feed heaters (for de-aerating) in Europe.[39][40][41]

By 1937 Permutit was manufacturing deaerators.[42][19]

In 1939, Cochrane, Darby, Elliott, Groeschel, Stearns-Rogers, Worthington, and others were competing against each other for business.[43] In 1949 Chicago Heater was formed and became a leading deaerator manufacturer.[44] In 1954, Allis-Chalmers, Chicago Heater, Cochrane, Elliott, Graver, Swartwout, Worthington, and others were in business.[45]

Applications

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Deaerators are used in many industries such as co-generation plants, hospitals, larger laundry facilities, oil fields, oil refineries, off-shore platforms, paper mills, power plants, prisons, steel mills, and many other industries.[citation needed]

See also

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  • Defoamer – Chemical additive that reduces and hinders the formation of foam in liquids
  • Degasification – Removal of dissolved gases from liquids

References

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  1. ^ "U.S. Department of Energy, Energy Efficiency & Renewable Energy, Advanced Manufacturing, Energy Tips: STEAM" (PDF). Energy.gov. January 2, 2012. Retrieved August 17, 2023.
  2. ^ "Water Treatment Deaerators". Newterra. 2023-01-05. Retrieved 2023-08-17.
  3. ^ a b c "The Deaerating Principle". Sterling Deaerator Company.
  4. ^ a b "Deaerators". Stork. Archived from the original on 2018-09-01. Retrieved 2016-09-30.
  5. ^ a b OSTI abstract. Retrieved April 23, 2021
  6. ^ "The Wichita Star 26 May 1887, page 1". Newspapers.com. Retrieved 2023-08-17.
  7. ^ "Iowa County Democrat 04 Mar 1881, page 2". Newspapers.com. Retrieved 2023-08-17.
  8. ^ US664763A, Kleucker, George M., "Method of deaerating water", issued 1900-12-25 
  9. ^ Carey, Stephen (2018-01-01). "Cold Starting the Titanic". Encyclopedia Titanica.
  10. ^ D, Ryan (2016-08-26). "10 of the Best Boiler Feed Water Treatment Equipment Supply and Technology Companies". SAMCO Technologies. Retrieved 2023-08-17.
  11. ^ "Montclair Times 01 Dec 1926, page 14". Newspapers.com. Retrieved 2023-08-17.
  12. ^ "The News 16 May 1928, page 7". Newspapers.com. Retrieved 2023-08-17.
  13. ^ "Vermont Tribune 13 Apr 1900, page 1". Newspapers.com. Retrieved 2023-08-17.
  14. ^ US1914166A, Rohlin, Victor A., "Apparatus for treating liquids", issued 1933-06-13 
  15. ^ US1596423A, Gibson, George H., "Water-deaerating apparatus", issued 1926-08-17 
  16. ^ US1877412A, Lyon, Percy S., "Deaerating water heater", issued 1932-09-13 
  17. ^ US1750035A, Stanley, Brown, "Deaerator", issued 1930-03-11 
  18. ^ "Intelligencer Journal 13 Feb 1958, page 42". Newspapers.com. Retrieved 2023-08-17.
  19. ^ a b US2204062A, Applebaum, Samuel B., "Water deaerator and purifier", issued 1940-06-11 
  20. ^ "Deaerator working principle". Boilers Info.
  21. ^ Standards and Typical Specifications for Tray Type Deaerators (10th ed.). Heat Exchange Institute. November 2016.
  22. ^ "The Feedtank and Feedwater Conditioning". Spirax Sarco.
  23. ^ Public Opinion, Chambersburg, PA, Feb 11, 1921. Retrieved Jan 25, 2022
  24. ^ Palladium-Item, Richmond, Indiana, Sep 24, 1934. Retrieved Jan 25, 2022
  25. ^ Union City Times-Gazette, Jul 23, 1940. Retrieved Jan 25, 2022
  26. ^ Paterson Evening News, Paterson, NJ, Sep 12, 1956.Retrieved Jun 4, 2023
  27. ^ STS Canada. Retrieved Mar 18, 2023
  28. ^ Hielscher. Retrieved Mar 18, 2023
  29. ^ Deaerator history. Retrieved Apr 24, 2021
  30. ^ Vancouver Sun, Apr 14, 1962. Retrieved Jun 4, 2023
  31. ^ US Dept of Energy, Deaerators in Industrial Steam Systems. Retrieved Mar 18, 2023
  32. ^ AMPP, NACE RFP050-96, Standard Recommended Practice. Retrieved April 22, 2021
  33. ^ The National Board of Boiler and Pressure Vessel Inspectors, April 1988. Retrieved April 22, 2021
  34. ^ US Dept of Energy, CIBO paper dated Nov 1997. Retrieved April 23, 2021
  35. ^ Proceedings of the American Power Conference paper, Otakar Jonas. Retrieved Jun 3, 2022
  36. ^ Stickle History, Retrieved April 23, 2021
  37. ^ Handbook, Chapter 14 Degasification. Retrieved April 23, 2021
  38. ^ Court Case, 1929. Retrieved April 23, 2021
  39. ^ The Guardian, Nov 2, 1951. Retrieved Mar 18, 2023
  40. ^ Daily Mail, Feb 9, 1925. Retrieved Mar 18, 2023
  41. ^ Perthshire Advertiser, Feb 27, 1909. Retrieved Mar 18, 2023
  42. ^ Intellingencer Journal, Feb 13, 1958. Retrieved Mar 18, 2023
  43. ^ Alliance Times-Herald, Mar 31, 1939. Retrieved Mar 18, 2023
  44. ^ Chicago Tribune, Jul 15, 1949. Retrieved Mar 18, 2023
  45. ^ News-Record, Aug 2, 1954. Retrieved Mar 18, 2023

Sources

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Further reading

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  • Betz Handbook of Industrial Water Conditioning, Chapter 9 boiler feedwater deaeration. 8th Edition, copyright 1980, LOC 79-56368.
  • NEA (National Environmental Agency) Paper, "Energy Best Practice Guide for Oil Refining
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