US 4,389,979 AGranted

Method and apparatus for the operation of a boiler installation with stoker firing

OwnerOddmund Saxlundinventor

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Abstract

A method and apparatus for the operation of a stoker-fired boiler having a boiler arranged coaxially adjacent to a stoker chamber. The cross-sectional area of the connection between the stoker and the boiler is constricted, preferably in the range of one-third to one-fourth of the cross-sectional area of the stoker chamber, so that the flammable gases flowing from the stoker to the boiler are accelerated and generate a reduced pressure at the constricted connection. Tertiary air is introduced at the circumference of the constricted connection at an increased pressure, to thereby induce more complete combustion of the gases. The area of flow flares out as the gas enters the boiler. In the preferred arrangement, guide means control the introduction of the tertiary air through an annular gap at the constricted connection The stoker also preferably includes rings of nozzles arranged at selected angles to introduce secondary air into the stoker chamber.

Claims11

Dependent claims

A method for the operation of a boiler installation with stoker firing having a stoker chamber with a burner grating for supporting combustion material and for the passage of the primary air, introducing secondary air through nozzles distributed over the periphery, and a tubular boiler placed coaxially adjacent to the stoker chamber with an approximately circular inner chamber having pipe means associating therewith and annular gas extraction means, said method comprising the steps of:

supplying the stoker chamber with primary and secondary air sufficient only for a partial combustion of said combustion material and producing a mixture of combustion gases and unburned gases ascending in said stoker chamber;
substantially reducing the cross-section of the flow from said stoker chamber of said combustion gases and unburned gases to provide a nozzle-like constricted flow as said gases are discharging from the stoker chamber into the boiler chamber and to generate a pressure at said constricted flow reduced with respect to the ambient pressure;
introducing tertiary air sufficient for complete combustion tangentially at the narrowest point of the constricted flow at a pressure increased with regard to the ambient pressure;
rotating the flow of the combustion gases and unburned gases discharging from the stoker chamber and mixing said discharging gases with said tertiary air;
initiating after-burning of the unburned gases at the narrowest point of the constricted flow;
substantially increasing the cross-section of the entire flow again by flaring the rotating flow outwardly upon its entry into said boiler chamber;
directing the rotating flow upwardly toward the ceiling of the boiler chamber and transferring heat from combustion gases to said pipe means;
annularly extracting part of the upwardly flowing gases by means of said boiler extraction means;
redirecting part of the flow downwardly back toward the constriction from the ceiling of the boiler in a central core-type current flow to re-mix with the gases flowing upwardly from the constriction;
whereby complete combustion occurs in said boiler chamber and partial combustion occurs in said stoker chamber.

7 more elements

A combustion apparatus comprising a stoker chamber with a burner grating for supporting combustion material and primary air ducts associated with the grating for the supply of fresh air, air supply nozzles distributed over the periphery of said stoker chamber for the supply of secondary air;

said primary air ducts and secondary air supply nozzles being controlled to provide less than sufficient air for complete combustion in the stoker chamber whereby during operation both combusted and uncombusted gases ascend in said stoker chamber;
a tubular boiler placed coaxially adjacent to the stoker chamber having an inner chamber with upper ceiling means, and annular gas extraction means;
means connecting the stoker chamber to the inner chamber of the boiler forming a nozzle-like constriction for receiving said ascending gases;
said tubular boiler flaring outwardly from said constriction;
and
a generally annular system to provide a tangential supply of pressurized tertiary air, sufficient for complete combustion, into said apparatus at the narrowest point of said nozzle-like constriction and being capable of placing ascending gases from said stoker chamber into rotation at said constriction and facilitate mixing with said tertiary air whereby after-burning of uncombusted gases initiates at said nozzle-like constriction and continues upwardly therefrom into said boiler inner chamber, and whereby said rotating gases flare outwardly and move upwardly from said constriction toward the ceiling means;
said annular system and boiler inner chamber being cooperative to facilitate flowing said rotating gases upwardly toward said ceiling means wherein a part of said upward flow is redirected at said ceiling means in a central downward core-type flow back toward said constriction to meet ascending gases from said stoker chamber and wherein part of said upwardly flowing gases is extracted at said extraction means;
pipe means associated with said boiler inner chamber capable of being heated by combusted gases;
and,
wherein complete burning of combustion gases is obtained in the boiler and part of the combustion occurs in the stoker chamber whereby said stoker chamber receives a reduced thermal charge permitting temperatures to be maintained below critical values.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/261,191Filed 1 May 1981
Priority: DE 29354943 Sep 1979
Granted: 28 Jun 1983
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

F23L 9/02
Passages or apertures for delivering secondary air for completing combustion of fuel: by discharging the air above the fire
F23B 1/36
Characterised by the form of combustion chamber: shaft-type
F23B 5/00
Combustion apparatus with arrangements for burning uncombusted material from primary combustion
F24H 9/1845
Arrangement or mounting of combustion heating means, e.g. grates or burners: using solid fuel