US3747571A - Predrying tunnels for mill drying devices - Google Patents

Predrying tunnels for mill drying devices Download PDF

Info

Publication number
US3747571A
US3747571A US00252447A US3747571DA US3747571A US 3747571 A US3747571 A US 3747571A US 00252447 A US00252447 A US 00252447A US 3747571D A US3747571D A US 3747571DA US 3747571 A US3747571 A US 3747571A
Authority
US
United States
Prior art keywords
tunnel
combustion chamber
predrying
tunnels
steam generator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00252447A
Other languages
English (en)
Inventor
R Kuhn
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.)
Deutsche Babcock and Wilcox AG
Original Assignee
Deutsche Babcock and Wilcox AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Deutsche Babcock and Wilcox AG filed Critical Deutsche Babcock and Wilcox AG
Application granted granted Critical
Publication of US3747571A publication Critical patent/US3747571A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C99/00—Subject-matter not provided for in other groups of this subclass
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23M—CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR
    • F23M5/00—Casings; Linings; Walls
    • F23M5/08—Cooling thereof; Tube walls
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
    • F23B2700/00—Combustion apparatus for solid fuel
    • F23B2700/012—Combustion apparatus for solid fuel with predrying in fuel supply area
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2700/00—Special arrangements for combustion apparatus using fluent fuel
    • F23C2700/06—Combustion apparatus using pulverized fuel
    • F23C2700/066—Other special arrangements

Definitions

  • l-lot gases are drawn from the combustion chamber of the steam generator through the predrying tunnels to dry wet coal injected into the tunnel before it drops to a plurality of mills which pulverize the coal.
  • a plurality of blowers coupled to the predrying tunnels draws the pulverized coal and gases from the tunnel and mills, and forces the gases and coal through the burners of the steam generator into the combustion chamber where the coal is ignited.
  • the present invention relates to steam generators, and in particular, to pipe-cooled predrying tunnels for a mill-drying device of the coal dust furnace type.
  • Predrying tunnels for steam generators are known in the prior art. See for example, West German Patent No. 969,609.
  • Predrying tunnels such as these, are generally disposed outside of the steam generator combustion chamber, and exhaust ports are provided in the combustion chamber walls to channel gases from the combustion chamber to the predrying tunnels.
  • some of the pipes used to cool the combustion chamber of the steam generator are mounted on the inner surfaces of the predrying tunnels.
  • the cooling pipes of each tunnel extend through openings in the combustion chamber cooling pipe wall, so that many co'oling pipes may be used to cool the tun nels.
  • the above-described cooling pipe structure for the predrying tunnels is disadvantageous since the cooling pipes are heated asymmetrically when the mill-drying device is run at a low capacity, or when the mill-drying device is not operated. This asymmetrical heating of the cooling pipes occurs over the cooling area of each predrying tunnel, which extends from its combustion chamber gas inlet port to the level at which coal is injected into the predrying tunnel.
  • the flow generated into steam by the steam generator is sensitive when the milldrying device operates at a low capacity, and could possibly become instable.
  • Asymmetrical admittance of heat to the cooling pipes is, thus, not desirable, and the predrying tunnel cooling pipes are limited to the exhaust outlet area of each tunnel, since the cooling pipes are heated by the flame of the furnace of the steam generator directly only at that area of the tunnels. It is not possible, therefore, to cool that portion of the predrying tunnels between the exhaust outlet of the tunnels and the level at which the coal is injected into the tunnels.
  • 'It is still another object of the present invention to provide a predrying tunnel for a mill-drying device of a steam generator which is simple in design, easy to manufacture and efficient and reliable in its operation.
  • the present invention provides a predrying tunnel for a mill-drying device of a steam generator in which the cooling pipes utilized to cool the combustion chamber wall of the steam generator are distributed in equal lengths over the inner walls of the predrying tunnels so that the steam generator flow is channeled through the cooling pipes disposed in the predrying tunnels.
  • Each of the cooling pipes surrounding the combustion chamber of the steam generator and disposed on the inner walls of the predrying tunnels are continuous and equal in length.
  • all bends in the cooling pipes are equal in length, and-fewer pipes are required than with conventional predrying tunnels.
  • the cooling pipes are easily manufactured, and since they have an even flow-through resistance, the flow characteristics through the pipes are stable. Furthermore, since the temperature of the cooling pipes in the predrying tunnels and the walls of the combustion chamber is maintained at a constant level, the predrying tunnels may be coupled to the combustion chamber walls and the pipes thereof may be welded tightly together. This eliminates the requirement of conventional predrying tunnels that a special carrier frame be provided for the. tunnels around the combustion chamber.
  • the predlrying tunnels of the present invention may be disposed either inside or outside of the combustion chamber walls of the steam generator. With either arrangement, the heat loss which occurs in the steam generator is less than that which occurs in conventional steam generators in which the predrying tunnels extend into free space. Furthermore, because of this optional configuration, the construction of the boiler frame for the steam generator and the mounting of the boiler frame, are both more inexpensive, faster and easier than with conventional steam generators, and dead angles may be used in the combustion chamber without producing a detrimental effect on the heat transfer which occurs in the combustion chamber, or on the combustion chamber flame.
  • the interior spaces of the predrying tunnels are separated from the combustion chamber by a vertical wall of cooling pipes, and openings are provided on the upper ends of the predrying tunnels to couple the tunnels with the combustionchamber.
  • the tunnels are not coupled to the combustion chamber at their lower ends.
  • the wall of cooling pipes separating the combustion chamber from the interior of the predrying tunnels serves both as a heating face for the combustion chamber and as a cooling face for the predrying tunnels.
  • This wall separating the tunnel and the combustion chamber comprises a' vertical array of two columns of pipes, the number of which is the same on both sides of the wall.
  • Each cooling pipe which forms the cooling face of the predrying tunnels has the same length, so that each pipe forming the cooling face of the predrying tunnels is heated by the same amount.
  • This construction prevents instability of the flow of the steam generator.
  • the total flow of the steam generator is channeled through the cooling pipes of the predrying tunnels in order to prevent instability of the flow caused by a unilateral change in the heating of the wall of cooling pipes separating the combustion chamber from the interior of the predrying tunnels.
  • a single wall of cooling pipes may be utilized to construct a single predrying tunnel and separate its interior from the combustion chamber of the steam generator.
  • the width of such a tunnel is designed so that the tunnel capacity is sufficient to meet the requirements of the steam generator.
  • FIG. 1 is a top cross-sectional view of the combustion chamber of a steam generator constructed in accordance with the present invention, taken along section l1 of FIG. 2;
  • FIG. 2 is a cross-sectional side view of the combustion chamber, taken along section 2-2 of FIG. 1;
  • FIG. 3 is an enlarged top cross-sectional view of one embodiment of a predrying tunnel constructed in accordance with the present invention.
  • FIG. 4 is an enlarged top cross-sectional view of another embodiment of a predrying tunnel constructed in accordance with the present invention.
  • the combustion chamber includes pipe walls 2 which consist of a continuous length of a pipe 4 coiled in a rectangular shape around the combustion chamber and superimposed over itself vertically.
  • the vertically-disposed array of pipes are welded together so as to be gas impermeable, and are suspended from the upper portion of a boiler frame 3.
  • the mounting apparatus 4 of the pipes is known in the art and presents no problem to persons of ordinary skill in the art.
  • Pulverized wet coal such as, for example, bitumen coal, having a water content greater than 35 percent, is burned in combustion chamber 1 to produce heat for the steam generator.
  • the coal is dried by hot gases drawn from the combustion chamber of the steam generator, and pulverized in a mill, before it is injected into the combustion chamber of the steam generator.
  • Hot gases produced by the flames in the combustion chamber of the steam generator are drawn from the combustion chamber through predrying tunnels to the mill used to pulverize the coal.
  • the coal to be burned in the combustion chamber is also drawn through the predrying tunnels to the mill so that the wet coal is dried while it drops through the tunnels.
  • these tunnels are known by those skilled in the art as predrying tunnels in a milldrying device.”
  • Suction blowers draw the hot gases from the combustion chamber and force the gases and the pulverized coal to the mill. From there, the gases and coal are forced through burners into the combustion chamber where the coal is ignited.
  • the predrying tunnels of the present invention are cooled by a plurality of continuous cooling pipes, through which the flow of the steam generator is channeled, between the gas intake ports of the tunnels and the level of the predrying tunnels at which the wet coal is injected into the tunnels to be dried by the gases as it drops downwardly towards the mills.
  • continuous pipe 4 forms a combustion chamber wall through which the steam-water mixture of the steam generator flows in the direction of arrow 5.
  • Pipe 4 is coiled around combustion chamber 1 in a continu' ous spiral, and is bent to form sections 6 and 7. Continuity of the pipe is maintained through these bends.
  • FIG. 2 the cooling pipes have not been illustrated to preserve clarity of the drawings.
  • pipe 4 is bent to form sections 6, which are of equal length.
  • Sections 6 form a vertical wall comprising two adjacent columns of pipes welded at one end to the wall of pipes around the combustion chamber so as to form a plurality of predrying tunnels 8.
  • Sections 7 of the pipe, disposed adjacent heat insulation material 20, form the outer walls of predrying tunnels 8 and are also equal in length. Instability in the flow of the steam-water mixture of the steam generator is prevented by insuring that the pipe sections are of equal length. The entire flow of the steam-water mixture of the steam generator is channeled through cooling pipe sections 6 and 7 of the predrying tunnels.
  • Hot gases produced by the flame in the combustion chamber are drawn off by gas intake ports 9 which are coupled to the upper portions of predrying tunnels 8.
  • the lower ends of the predrying tunnels are not coupled to the combustion chamber and are closed off by plates 10.
  • Predrying tunnels 8 are coupled to lateral tunnels 11 in which the wet coal is injected by feeding means 12, which may be a chute.
  • Predrying of the coal begins as the wet coal drops through tunnel sections 13.
  • the mills also include larger paddle wheels 15 which also pulverize the coal, and draw out the gas and the coal dust from mills l4.
  • Paddle wheels 15 draw the hot gases from the combustion chamber 1 through ports 9, tunnels 8, l1 and 13 into mills l4. Tunnels 8 are cooled by the cooling pipes as the gases are drawn therethrough.
  • the pulverized, dried coal is forced by paddle wheels 15 upwardly through feed pipes 16 to burners 17, which inject the coal into combustion chamber 1 with the cooled gases.
  • Air is fed to burners 17 through air feed pipes 18 to aid in the combustion and ignition of the pulverized coal.
  • Air supply couplings 19 are also coupled to tunnel sections 13 to regulate the drying temperature by admitting cool air in controlled amounts.
  • the predrying tunnels are constructed wide enough so that each may beprovided with two predrying tunnel sections 11 and 13 and two mill-drying and blower devices 14 and 15.
  • the amount of the coal dust and gas which is injected by burners 17 into combustion chamber l is adjusted by regulating the air supply to each of the predrying tunnels and burners.
  • the apparatus may be adjusted to compensate for the effects produced when one or more of mills 14 is inoperative or operating at a low capacity.
  • the heating of cooling pipes 6 and 7 in the predrying tunnels is different, heat is admitted in equal amounts to pipe walls 2 between cooling pipes 6 and 7 since each of the pipe walls is of the same length.
  • the superimposed arrangement of the cooling pipes between the predrying tunnels also distributes the irregularities of the heating process to the total length of pipe 4.
  • FIG. 4 another embodiment of a predrying tunnel is disclosed.
  • pipe 4 is bent in a circular coil and is disposed within the heat insulation material 20 of pipe walls 2.
  • Predrying tunnels 8 formed by these coils are substantially the same as the abovedescribed predrying tunnels.
  • Tunnels 8 comprise a plurality of circular coils superimposed upon each other, each coil being of the same length to prevent instability of the flow through the cooling pipes.
  • the materials used to construct the steam generator combustion chamber described above may be of any suitable conventional type. Selection of these materials will present no problem to those persons skilled in the art.
  • predrying tunnels When predrying tunnels are constructed in accordance with the present invention, it is not necessary to provide a fire-proof lining or casing for the interior of the tunnels. Slag also does not form on the walls of the predrying tunnels, and the air flow between the walls does not, therefore, become constricted.
  • the predrying tunnels are mounted on the mounting frame of the steam generator along with pipe walls 2, and thus do not require separate mounting means. The heat loss of a combustion chamber constructed as described above is also reduced since the predrying tunnels are encompassed in the heat insulation material 20 of the steam generator combustion chamber.
  • combustion chamber 1 may be constructed as a vertically rotating burner chamber of rectangular shape.
  • Cooling pipe sections 6 and 7 of the predrying tunnels form heating faces which reduce the heat in combustion chamber 1 and prevent the steam-water mixture flowing through pipe walls 2 from completely evaporating.
  • cooling pipe sections 6 and 7 function as unheated throttle areas so that sections of pipe 4 within pipe walls 2 are heated more intensely and move evenly and the flow stability of the steam-water mixture is improved.
  • mills 14 are operated more economically.
  • a predrying tunnel for the combustion chamber of a steam generator comprising:
  • said paddle wheel mill further comprises blower means, for drawing gases from the combustion chamber through said vertical tunnel and said cylindrical tunnel into said mill, and forcing the pulverized fuel and said gases into the combustion chamber of the steam generator.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Drying Of Solid Materials (AREA)
  • Combustion Of Fluid Fuel (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
  • Detergent Compositions (AREA)
US00252447A 1971-05-13 1972-05-11 Predrying tunnels for mill drying devices Expired - Lifetime US3747571A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19712123681 DE2123681A1 (Direct) 1971-05-13 1971-05-13

Publications (1)

Publication Number Publication Date
US3747571A true US3747571A (en) 1973-07-24

Family

ID=5807717

Family Applications (1)

Application Number Title Priority Date Filing Date
US00252447A Expired - Lifetime US3747571A (en) 1971-05-13 1972-05-11 Predrying tunnels for mill drying devices

Country Status (7)

Country Link
US (1) US3747571A (Direct)
AU (1) AU468154B2 (Direct)
CS (1) CS164762B2 (Direct)
DD (1) DD96327A1 (Direct)
DE (1) DE2123681A1 (Direct)
RO (1) RO65393A (Direct)
SU (1) SU499838A3 (Direct)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19940933C1 (de) * 1999-08-27 2000-10-05 Alstom Energy Syst Gmbh Tangentialfeuerung zur Verfeuerung von staubförmigem Brennstoff

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2856872A (en) * 1954-03-31 1958-10-21 Kohlenscheidungs Gmbh Pulverized coal firing system
US3274961A (en) * 1964-12-29 1966-09-27 Combustion Eng System for heating air and drying fuel

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2856872A (en) * 1954-03-31 1958-10-21 Kohlenscheidungs Gmbh Pulverized coal firing system
US3274961A (en) * 1964-12-29 1966-09-27 Combustion Eng System for heating air and drying fuel

Also Published As

Publication number Publication date
RO65393A (fr) 1979-07-15
DD96327A1 (Direct) 1973-03-12
CS164762B2 (Direct) 1975-11-28
AU4222472A (en) 1973-11-15
AU468154B2 (en) 1976-01-08
SU499838A3 (ru) 1976-01-15
DE2123681A1 (Direct) 1972-11-16

Similar Documents

Publication Publication Date Title
US2357301A (en) Fuel burning method and apparatus
US3105540A (en) Method of and apparatus for burning low heat content fuel
US3224419A (en) Vapor generator with tangential firing arrangement
BR112014003286B1 (pt) Aparelho e método para tratamento térmico de material em pedaços ou aglomerado
US3393652A (en) Refuse disposal system
US3747571A (en) Predrying tunnels for mill drying devices
RU2068152C1 (ru) Многоструйная трубчато-щелевая горелка
US2114619A (en) Apparatus for burning bagasse and like fuels
US3865084A (en) Inner furnace air chamber
US4343247A (en) Fluidized bed combustion method and apparatus
US4176623A (en) Fluidized bed boiler
US2654350A (en) Combustion chamber
US3394695A (en) Heating apparatus
US2498761A (en) Fuel burning apparatus
US2022427A (en) Fuel burning apparatus
US2492942A (en) Roller hearth furnace
US1993072A (en) Boiler
US2986139A (en) Heater for gaseous working mediums of thermal power plants
US2953364A (en) Coal drying furnace breeching
US2057622A (en) Mechanical stoker
US2861526A (en) Fuel burning apparatus
RU2083925C1 (ru) Котельная установка
US3153402A (en) Steam generator
US1770987A (en) Art of burning finely-divided fuel for the generation of steam
US2871833A (en) Method of and apparatus for vapor superheat temperature control with gas recirculation