Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23H—GRATES; CLEANING OR RAKING GRATES
  • F23H11/00—Travelling-grates
  • F23H11/10—Travelling-grates with special provision for supply of air from below and for controlling air supply
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B1/00—Combustion apparatus using only lump fuel
  • F23B1/16—Combustion apparatus using only lump fuel the combustion apparatus being modified according to the form of grate or other fuel support
  • F23B1/22—Combustion apparatus using only lump fuel the combustion apparatus being modified according to the form of grate or other fuel support using travelling grate
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B30/00—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber
  • F23B30/02—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts
  • F23B30/06—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts with fuel-supporting surfaces that are specially adapted for advancing the fuel through the combustion zone
  • F23B30/08—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts with fuel-supporting surfaces that are specially adapted for advancing the fuel through the combustion zone with fuel-supporting surfaces that move through the combustion zone, e.g. with chain grates

Definitions

• the subject of the invention is a stoker-fired boiler containing in the combustion zone a movable stoker and an under-stoker wind boxes system, a method of modernization of such a boiler as well as a method of elimination of uncontrolled leakages of air not taking part in the combustion process in the boiler.
• the pressure is close to the pressure in the combustion chamber, and usually amounts to some -30 to -50 Pa.
• the appearing differences in pressure between the wind box spaces, the under-stoker space, and the atmosphere cause flows of uncontrolled leakages of air streams through the gaps existing between these spacer, however prober manufacturing of a boiler does not ensure its complete tightness.
• Sealing of the said spaces in a stoker-fired boiler meaning the elimination of uncontrolled leakages of air not taking part in the solid fuel combustion process, was subject of many solutions and attempts. From the Polish patent No. 183654 description, it is known that a stoker-fired boiler burner has already been sealed by means of metallic membrane walls.
• Migration of air streams within a stoker-fired boiler may also be controlled through the appropriate shaping of wind boxes of the under- stoker wind boxes system.
• a boiler according to the invention contains an combustion chamber with a secondary air channel, a movable mechanical stoker, and an under-stoker space containing an under-stoker wind boxes system with wind boxes, as well as a channel supplying the air into the inside of the wind boxes.
• the essence of the invention is that the boiler contains an additional air channel with an inbuilt fan with adjustable output. One end of this additional air channel is connected with the under-stoker space located outside of the wind boxes of the under-stoker wind boxes system.
• the other end of the additional air channel is connected with either the space of the channel supplying the external air to the wind boxes of the under-stoker wind boxes system, or with the atmosphere or with the secondary air channel of the combustion chamber.
• At least one air temperature sensor in the space of the channel supplying the air from the atmosphere to the inside of the wind boxes as well as in the space of the additional air channel is located at least one air temperature sensor. These sensors may be connected to controller of the fan of the additional air channel.
• a method of modernization according to the invention consists in that the under- stoker space of the aforementioned boiler, located outside of the wind boxes of the under-stoker wind boxes system, is connected with the first end of the additional air channel having an inbuilt fan with adjustable output.
• the other end of the additional air channel is connected with either the space of the channel supplying the air to the wind boxes of the under-stoker wind boxes system, or with the atmosphere or with the secondary air channel of the combustion chamber.
• in the space of the channel supplying the air from the atmosphere to the inside of the wind boxes, as well as in the space of the additional air channel is located at least one air temperature sensor.
• the method of elimination of uncontrolled air leakages consists in leading out and air from the under-stoker space of a boiler, located outside of the wind boxes of the under-stoker wind boxes system, to an additional air channel having an inbuilt fan with changeable output. Current output of this fan is proportional to the current difference between temperature of air supplied to the wind boxes, and the temperature of air in the additional air channel.
• the air led out to the additional air channel is either supplied to the wind boxes of the under-stoker wind boxes system, or is led out further into the atmosphere, or supplied to the secondary air channel of the combustion chamber of the boiler.
• the invention reduces the amount of air coming through the gaps and combining with the combustion fumes, giving in consequence a reduced coefficient of excess air in the fumes. This results in a reduction of a physical loss in the fumes, which also means the increase of boiler performance, usually by about 2 to 5%, depending on its technical condition, changes of the load, quality of the combustion charge, and proper maintenance and operation.
• the application of the invention also reduces the consumption of electric power by the components of the boiler by approximately 10-20%.
• the load of the extractor fan is smaller, and the consumption of energy by the fan of the additional air channel is balanced by limited energy consumption by the wind boxes air fan.
• a beneficial feature of the invention is also a short time needed for the modernization of the boiler, and a low cost of such modernization that amounts to ca. 10% of the cost of replacement of the under-stoker wind boxes system.
• fig. 1. presents a boiler with the first variant of an additional air channel
• fig. 2 presents a boiler with the second variant of this channel
• fig. 3 presents a boiler with the third variant of such a channel.
• a typical stoker-fired boiler has a fume zone with a fume extractor fan 1 , and a burner zone.
• a burner zone In the burner zone there is an combustion chamber 2, a movable mechanical stoker 3, an under-stoker wind boxes system 4 with wind boxes 5, and a channel 6 supplying the air from the atmosphere to the inside of the wind boxes 5 by means of a wind boxes air fan 7.
• the combustion chamber 2 has a secondary air channel powered by a fan 8.
• the boiler according to the invention has an additional air channel 9 with an inbuilt fan 10 with adjustable output. One end 9 1 of the additional air channel 9 is connected with the under-stoker space 11 located outside of the wind boxes 5 of the under-stoker wind boxes system 4.
• the other end 9" of the additional air channel 9 may be connected with either the space of channel 6 supplying external air to the wind boxes 5 of the under-stoker wind boxes system 4, or with the atmosphere or with the secondary air channel of the combustion chamber 2.
• an appropriate amount of air deriving from uncontrolled leakages is removed from the under-stoker zone 11 , and directed to a selected place via the additional air channel 9.
• Output of the fan 10 may be controlled manually, whereas it is beneficial to use for this purpose the knowledge of air temperature in the space of channel 6 supplying it from the atmosphere to the inside of the wind boxes 5, and temperature of the air in the space of the additional air channel 9. In order to do so, in these places at least one air temperature sensor (not shown in the drawings) should be placed.
• the difference between the temperature of wind boxes air stream in the channel 6, and temperature of air stream in the additional air channel 9 not exceeding 5°C shows that through channel 9 flows only the air coming from uncontrolled leakages to the under-stoker space.
• the difference in temperatures amounting to 5 to 1O 0 C constitutes information that in the additional air channel 9 there also is the air deriving from uncontrolled leakages taking place through the section of the stoker 3 on which the combustion process no longer takes place or takes place into a limited extent. In this case, uncontrolled leakages take place towards the bottom part of the combustion chamber 2, and their reception has positive effects on the physical loss in the fumes.
• the difference in temperature exceeding 10 0 C constitutes information that into the channel 9 additionally flow some of the fumes from the combustion chamber 2 without resulting in a physical loss in the fumes.
• These dependencies allow for automation of the adjustment of output of the fan 10, through connecting of the said temperature sensors to the fan controller, and the application of the difference between the temperatures measured by means of these sensors as a control parameter. It unexpectedly appeared that with small loads of the boiler, amounting to for instance 10-20% of the nominal load, the amount of air coming from the gaps is sufficient to conduct the process of combustion. In such a situation, when there is no possibility to isolate the channel 6 from the atmosphere, the wind boxes air fan 7 stops supplying air for the combustion process and only starts to block the out-flow of air from the boiler.
• Connecting of the first wind box separated from the stream of wind boxes air with the under-stoker space allows boiler operators to control the distance of the point of coal ignition on the stoker from the slide gate and the front part of the boiler structure. Similarly, connecting of the last non-operating wind boxes with the under-stoker space after prior separation from the stream of wind boxes air reduces uncontrolled leakages from the wind boxes space to the combustion chamber.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Air Supply (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Incineration Of Waste (AREA)
• Fluidized-Bed Combustion And Resonant Combustion (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Combustion Of Fluid Fuel (AREA)
• Gasification And Melting Of Waste (AREA)
• Control Of Steam Boilers And Waste-Gas Boilers (AREA)

Priority Applications (2)

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• 2007
  • 2007-12-03 PL PL383941A patent/PL383941A1/pl not_active IP Right Cessation
• 2008
  • 2008-12-01 EP EP12157001.4A patent/EP2461098A3/fr not_active Withdrawn
  • 2008-12-01 WO PCT/PL2008/000092 patent/WO2009072909A2/fr not_active Ceased
  • 2008-12-01 CN CN2008801187198A patent/CN101896771A/zh active Pending
  • 2008-12-01 US US12/734,889 patent/US20100307393A1/en not_active Abandoned
  • 2008-12-01 AU AU2008332014A patent/AU2008332014A1/en not_active Abandoned
  • 2008-12-01 CA CA2705730A patent/CA2705730A1/fr not_active Abandoned
  • 2008-12-01 EP EP08858195A patent/EP2217858B1/fr active Active
  • 2008-12-01 AT AT08858195T patent/ATE552463T1/de active
  • 2008-12-01 PL PL08858195T patent/PL2217858T3/pl unknown
  • 2008-12-01 UA UAA201008013A patent/UA94868C2/ru unknown
  • 2008-12-01 RU RU2010126547/06A patent/RU2447371C2/ru not_active IP Right Cessation

Non-Patent Citations (1)

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