US3910236A - Economizer for steam boiler - Google Patents

Economizer for steam boiler Download PDF

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Publication number
US3910236A
US3910236A US513555A US51355574A US3910236A US 3910236 A US3910236 A US 3910236A US 513555 A US513555 A US 513555A US 51355574 A US51355574 A US 51355574A US 3910236 A US3910236 A US 3910236A
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US
United States
Prior art keywords
coil
feedwater
economizer
flue gases
inlet
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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.)
Expired - Lifetime
Application number
US513555A
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English (en)
Inventor
Jr John H Merritt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
APPLIED ENG CO
APPLIED ENGINEERING Co
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APPLIED ENG CO
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Publication date
Application filed by APPLIED ENG CO filed Critical APPLIED ENG CO
Priority to US513555A priority Critical patent/US3910236A/en
Priority to CA236,756A priority patent/CA1024841A/fr
Application granted granted Critical
Publication of US3910236A publication Critical patent/US3910236A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/02—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways
    • F22D1/08—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways the tubes having fins, ribs, gills, corrugations, or the like on their outer surfaces, e.g. in vertical arrangement
    • F22D1/10—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways the tubes having fins, ribs, gills, corrugations, or the like on their outer surfaces, e.g. in vertical arrangement in horizontal arrangement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/02—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways
    • F22D1/12—Control devices, e.g. for regulating steam temperature

Definitions

  • ABSTRACT [22] Filed: 1974
  • the economizer disclosed herein includes a coil posi- [21] Appl. No.: 513,555 tioned in the flue gas duct of a steam boiler.
  • the feedwater source is connected to the feedwater inlet of the boiler through the economizer coil or by-passes the U.S.
  • economizer Coil is connectd i y to the feed Clwater inlet means of a three way valve that g Fleld of Search ates the amount of feedwater flowing through the 122/439 420 economizer coil or by-passing the coil in response to a temperature sensing device that detects the tempera- [56] References and ture of the flue gases after passage around the coil so UNITED STATES PATENTS that the temperature of the flue gases after passing 666,537 1/1901 Levi et a1 122/439 around the coil is maintained above the dew point of 1,565,304 l2/l925 Bell 122/421 the flue gases.
  • the apparatus of the invention includes an economizer coil positioned in the flue gas duct of a steam boiler.
  • the feedwater source is connected to the feedwater inlet of the boiler through the economizer coil and directly to the feedwater inlet of the boiler bypassing the economizer coil.
  • a three-way valve regulates the amount of feedwater flowing through the economizer coil and by-passing the coil in response to a temperature sensing device that detects the temperature of the flue gases after passage around the coil so that the temperature of the flue gases after passage around the coil is maintained above the dew point of the flue gases.
  • FIG. 1 is a view illustrating the invention installed on a steam boiler; and, 7
  • FIG. 2 is a schematic diagram of the invention.
  • the economizer unit 10 embodying the invention is mounted on a conventional steam boiler B with a flue gas duct D and a feedwater connection FC so that the feedwater passes through a feedwater regulator valve RV into boiler B.
  • a feedwater source FS is normally associated with boiler B to supply feedwater under pressure to the feedwater connection FC.
  • the economizer unit 10 includes an economizer heat exchange coil 11 best seen in FIG. 2 which is interposed in the flue gas duct D so that the flue gases flow around the coil 11 in a heat transfer relationship therewith as they pass through duct D.
  • a feedwater flow control system 12 is also included in unit I which can selectively cause the feedwater from the feedwater source F to through the coil 1 I and then into the feedwater connection FC. and cause the feedwater to pass directly from the feedwater source FS into the feedwater connection FC by-passing the coil 11.
  • the flow of the feedwater through the coil II and bypassing the coil II is proportioned by the flow control system so that the temperature of the flue gases after passage around coil 11 is above the dew point of the flue gases.
  • a fan unit 14 may be used in the duct D in conjunction with unit 10 to offset the pressure loss across the unit 10. This allows unit 10 to be introduced into duct D without affecting the operational efficiency of boiler B due to pressure loss as the flue gases pass around the coil 11.
  • Coil 11 is mounted in a side wall 15 defining a passage 16 therethrough with a cross-section similar to duct D.
  • Coil 11 has a series of heat transfer tubes 20 that extend between an inlet header 21 and an exit header 22 along a serpentine path across passage 16 through which the flue gases pass.
  • Extended surface fins 24 may be provided on tubes 20 to increase the heat transfer efficiency thereof.
  • the inlet header 21 is provided with a feedwater inlet 25 and the exit header 22 is provided with a feedwater outlet 26.
  • the feedwater inlet to economizer unit 10 is connected to the feedwater source FS through a pipe 28.
  • the feedwater outlet 26 of economizer unit 10 is connected to one valve inlet 29 of a three-way by-pass valve 30.
  • the valve outlet 31 of by-pass valve is connected to the feedwater connection PC on the boiler B.
  • the other valve inlet 32 of by-pass valve 30 is also connected to the pipe 28 through a by-pass pipe 34 in parallel across coil 11 so that the by-pass valve 30 can be used to selectively control the feedwater flow through the economizer coil 11 and the by-pass pipe 34 bypassing the coil 11.
  • the by-pass valve 30 has a control mechanism 36 thereon which selectively operates the valve 30 so that the amount of feedwater that flows into the valve from the one valve inlet 29 or the other valve inlet 32 can be selectively controlled. While any number of by-pass valve constructions may be used, the valve 30 illustrated is a pneumatically operated proportioning valve which can proportion the flow between the valve inlets 29 and 32. One commercially available valve which operates in this manner is a commercial model three-way by-pass proportioning valve manufactured by the DeZurit Company and is pneumatically operated through a positioning cylinder actuator.
  • the by-pass valve 30 is operated in response to the average flue gas temperature passing out of the coil 11.
  • This control is provided by a temperature sensor 40 positioned in the economizer unit so that the sensor 40 senses the temperature of the flue gases after passage through the coil 1 l and not the metal temperature.
  • the temperature sensor 40 produces an electrical output which is connected to a control unit 41 that converts the electrical output of the temperature sensor into a pneumatic output that is connected to the three-way by-pass valve 30 to control the operation thereof.
  • the temperature sensor 40 can be any of a number of devices with the unit being illustrated as an averaging thermocouple 42.
  • the averaging thermocouple 42 is located in passage 16 downstream of the downstream most heat transfer tube 20 of coil 11 and averages the temperature of the flue gases after passage around the coil 11 to produce an electrical output therefrom proportional to the temperature of the flue gases. While different kinds of averaging thermocouples 42 may be used, one commercially available unit which has been used successfully is a type J averaging thermocouple manufactured by Barber-Coleman Co.
  • the control unit 41 includes a thermocouple controller 44 designed to operate with the averaging thermocouple 42.
  • one unit that has been used successfully is a controller manufactured by Barber-Coleman Co. as their 520 Series Setpoint Controller.
  • the output of the thermocouple controller 44 is connected to a currentto-pneumatic transducer 45 which converts the electrical signal output from the thermocouple 42 into a pneumatic output. While any of a number of transducers 45 may be used, one unit that has operated successfully is a unit manufactured by Barber-Coleman Co, under its designation Series P02R Current-to- Pneumatic Transducer.
  • the output of the transducer 45 is connected to the control mechanism 36 at the valve 30.
  • the controller 44 can be adjusted so that the feedwater flowing through the coil 11 and by-passing the coil 11 through the by-pass pipe 34 can be proportioned by the valve 30 in response to the outlet temperature of the flue gases after passage about the coil 11 to maintain the flue gases within a prescribed temperature range.
  • the temperature sensor 40 controls the three-way valve 30 in such a way that the feedwater flow is controlled to maintain the flue gas temperature after passing through the heat exchange coil 11 at a prescribed value to prevent condensation of the corrosive chemical compounds in the flue gases on the coil 11 and the attendant corrosion of the coil 11.
  • the dew point of the flue gases is determined primarily by the sulfur content of the fuel being burned. Because the sulfur content in the fuel varies between the different geographical sources of the fuel, each batch of fuel burned may have a different dew point. Thus, the user adjusts the controller 44 each time the sulfur content varies to insure that the average gas temperature is above its dew point after passage about the coil 1 1.
  • the amount of feedwater passing through the coil 11 is directly proportional to the amount the actual temperature of the flue gases is above the prescribed temperature range set on controller 44.
  • the amount of feedwater by-passing coil 11 is inversely proportional to the amount the actual temperature of the flue gases is above the prescribed temperature range.
  • the by-pass valve 30 can be positioned on the feedwater inlet valve of the heat exchange coil 11 without departing from the scope of the invention.
  • a check valve may be required in the outlet of the coil 11 to prevent the feedwater on the downstream side of the coil 11 flowing back into the coil.
  • An economizer unit for use with a steam boiler having a feedwater inlet, a feedwater source, and an exhaust duet through which heated flue gases are discharged, said economizer unit comprising:
  • flow control means for selectively directing feedwater to the feedwater inlet of said boiler through said economizer coil to heat the feedwater and directly to the feedwater inlet by-passing said economizer coil, said flow control means response to the average temperature of the flue gases after passage around said economizer coil to maintain the temperature of the flue gases after passage around said economizer coil within a prescribed temperature range above the dew point of the flue gases.
  • a flow control valve operatively connecting said economizer coil and the feedwater inlet to the feedwater source, and connecting said economizer coil to the feedwater inlet to selectively direct feedwater from the feedwater source through said economizer coil to the feedwater inlet on the steam boiler and from the feedwater source to the feedwater inlet on the steam boiler by-passing said economizer coil;
  • thermosensoring means for sensing the temperature of the flue gases after passage around said economizer coil
  • control circuit means operatively connected to said flow control valve and said temperature sensing means to cause said flow control valve to direct the flow of feedwater through said coil and by-passing said coil so as to maintain the flue gases in said prescribed temperature range after passage around said economizer coil.
  • thermocouple 3. The economizer unit of claim 2 wherein said tem perature sensing means is an averaging thermocouple.
  • said flow control means further includes a three-way valve having a first inlet, a second inlet and an outlet, said valve selectively connecting said first and second inlets to said outlet, said first inlet operatively connected to the feedwater source through said economizer coil, said second inlet connected to the feedwater source by-passing said coil. and said outlet connected to the feedwater inlet of the boiler; and temperature responsive control means operatively connected to said valve to cause the feedwater to be selectively directed through said coil and by-passing said coil to maintain the temperature of the flue gases after passage around said coil within said prescribed temperature range.
  • a method of transfering heat in the flue gases of a steam boiler to the feedwater to the boiler comprising the steps of:
  • step of dividing the flow of feedwater includes controlling the amount of feedwater flowing through the economizer coil directly proportionally to the amount the actual temperature of the flue gases after passage around the coil is above said prescribed temperature range, and controlling the amount of feedwater by-passing the economizer coil inversely proportionally to the amount the actual temperature of the flue gases after passage around the coil is above said prescribed temperature range.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
US513555A 1974-10-10 1974-10-10 Economizer for steam boiler Expired - Lifetime US3910236A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US513555A US3910236A (en) 1974-10-10 1974-10-10 Economizer for steam boiler
CA236,756A CA1024841A (fr) 1974-10-10 1975-09-30 Economiseur pour chaudiere a vapeur

Applications Claiming Priority (1)

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US513555A US3910236A (en) 1974-10-10 1974-10-10 Economizer for steam boiler

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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4138969A (en) * 1977-07-08 1979-02-13 Applied Engineering Co. Heat exchanger and economizer
US4173949A (en) * 1978-01-23 1979-11-13 Tranter, Inc. Feedwater preheat corrosion control system
EP0059898A2 (fr) * 1981-03-04 1982-09-15 Peter Babberger Méthode pour l'utilisation d'une installation de chauffage central à eau chaude avec un échangeur de chaleur séparé pour les gaz de combustion
US4371027A (en) * 1975-09-10 1983-02-01 Jacobsen Orval E Economizer with an integral gas bypass
US4373473A (en) * 1981-03-16 1983-02-15 110707 Canada Ltee Heat recuperating water heating system
WO1994015147A1 (fr) * 1992-12-29 1994-07-07 Combustion Engineering, Inc. Systeme economiseur pour appareil de generation de vapeur
US7504260B1 (en) * 2000-05-16 2009-03-17 Lang Fred D Method and apparatus for controlling gas temperatures associated with pollution reduction processes
US20100229805A1 (en) * 2009-03-10 2010-09-16 Cerney Brian J Integrated split stream water coil air heater and economizer (iwe)
US20100326373A1 (en) * 2009-06-30 2010-12-30 9223-5183 Quebec Inc. Boiler with improved hot gas passages
CN102913896A (zh) * 2012-11-20 2013-02-06 上海锅炉厂有限公司 一种电站锅炉省煤器
US20140013653A1 (en) * 2012-07-13 2014-01-16 Kenneth Lander Thermal Processing Device, System, and Method.
WO2014159380A3 (fr) * 2013-03-14 2015-06-04 Siemens Aktiengesellschaft Dilution de gaz de fumée localisé dans un générateur de vapeur à récupération de chaleur
WO2016096847A1 (fr) * 2014-12-19 2016-06-23 Alstom Technology Ltd Système et procédé de préchauffage d'un milieu fluide
US10393369B2 (en) 2014-04-28 2019-08-27 General Electric Company System and method for fluid medium preheating
WO2022074633A1 (fr) * 2020-10-10 2022-04-14 Forbes Marshall Private Limited Chaudière dotée d'un économiseur

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1156886A (fr) * 1979-11-21 1983-11-15 Ardell Beckett Systeme recuperateur de chaleur des gaz d'echappement

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US666537A (en) * 1900-02-21 1901-01-22 Massimo Levi Superheating apparatus for feed-water of marine boilers.
US1565304A (en) * 1919-11-07 1925-12-15 Power Specialty Co Economizer for steam boilers
US2699759A (en) * 1951-11-17 1955-01-18 Riley Stoker Corp Feed water heating
US2704534A (en) * 1955-03-22 Method of and apparatus for regulating and improving

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2704534A (en) * 1955-03-22 Method of and apparatus for regulating and improving
US666537A (en) * 1900-02-21 1901-01-22 Massimo Levi Superheating apparatus for feed-water of marine boilers.
US1565304A (en) * 1919-11-07 1925-12-15 Power Specialty Co Economizer for steam boilers
US2699759A (en) * 1951-11-17 1955-01-18 Riley Stoker Corp Feed water heating

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4371027A (en) * 1975-09-10 1983-02-01 Jacobsen Orval E Economizer with an integral gas bypass
US4138969A (en) * 1977-07-08 1979-02-13 Applied Engineering Co. Heat exchanger and economizer
US4173949A (en) * 1978-01-23 1979-11-13 Tranter, Inc. Feedwater preheat corrosion control system
EP0059898A2 (fr) * 1981-03-04 1982-09-15 Peter Babberger Méthode pour l'utilisation d'une installation de chauffage central à eau chaude avec un échangeur de chaleur séparé pour les gaz de combustion
EP0059898A3 (fr) * 1981-03-04 1983-04-13 Peter Babberger Méthode pour l'utilisation d'une installation de chauffage central à eau chaude avec un échangeur de chaleur séparé pour les gaz de combustion
US4373473A (en) * 1981-03-16 1983-02-15 110707 Canada Ltee Heat recuperating water heating system
WO1994015147A1 (fr) * 1992-12-29 1994-07-07 Combustion Engineering, Inc. Systeme economiseur pour appareil de generation de vapeur
US7504260B1 (en) * 2000-05-16 2009-03-17 Lang Fred D Method and apparatus for controlling gas temperatures associated with pollution reduction processes
US8286595B2 (en) * 2009-03-10 2012-10-16 Babcock & Wilcox Power Generation Group, Inc. Integrated split stream water coil air heater and economizer (IWE)
US20100229805A1 (en) * 2009-03-10 2010-09-16 Cerney Brian J Integrated split stream water coil air heater and economizer (iwe)
US20100326373A1 (en) * 2009-06-30 2010-12-30 9223-5183 Quebec Inc. Boiler with improved hot gas passages
US9404650B2 (en) 2009-06-30 2016-08-02 M. Alexandre Lapierre Boiler with improved hot gas passages
US20140013653A1 (en) * 2012-07-13 2014-01-16 Kenneth Lander Thermal Processing Device, System, and Method.
US9339021B2 (en) * 2012-07-13 2016-05-17 Kenneth Lander Thermal processing device, system, and method
CN102913896A (zh) * 2012-11-20 2013-02-06 上海锅炉厂有限公司 一种电站锅炉省煤器
WO2014079247A1 (fr) * 2012-11-20 2014-05-30 上海锅炉厂有限公司 Économiseur pour chaudière de centrale
WO2014159380A3 (fr) * 2013-03-14 2015-06-04 Siemens Aktiengesellschaft Dilution de gaz de fumée localisé dans un générateur de vapeur à récupération de chaleur
US9587828B2 (en) 2013-03-14 2017-03-07 Siemens Aktiengesellschaft Localized flue gas dilution in heat recovery steam generator
US10393369B2 (en) 2014-04-28 2019-08-27 General Electric Company System and method for fluid medium preheating
WO2016096847A1 (fr) * 2014-12-19 2016-06-23 Alstom Technology Ltd Système et procédé de préchauffage d'un milieu fluide
WO2022074633A1 (fr) * 2020-10-10 2022-04-14 Forbes Marshall Private Limited Chaudière dotée d'un économiseur

Also Published As

Publication number Publication date
CA1024841A (fr) 1978-01-24

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