DK9700348U3

DK9700348U3 - Stoker stove for wood pellets

Info

Publication number: DK9700348U3
Application number: DK9700348U
Authority: DK
Inventors: Erik Lauritsen
Original assignee: Greenfire Aps
Priority date: 1997-09-23
Filing date: 1997-09-23
Publication date: 1997-12-29
Also published as: WO1999015833A1; AU9253998A

Description

DK 97 00348 U3DK 97 00348 U3

BESKRIVELSEDESCRIPTION

BenævnelseDenominations

Stokerbrændeovn til træpiller Frembringelsens anvendelsesområdeStoker stove for wood pellets The scope of production

Denne frembringelse angår en stokerbrændeovn til træpiller og lignende typer fast brændsel i pilleret eller granuleret form. Stokerbrændeovnen er især beregnet til opvarmning af enfamiliehuse, lejligheder, fritidshuse og andre steder, hvor der er behov for en økonomisk og miljøvenlig form for rumopvarmning. Stokerbrændeovnen er først og fremmest tænkt som et alternativ til konventionelle brændeovne af den type, som er beregnet til manuel indfyring med brændetræ, men kan i visse tilfælde også erstatte egentlige centralvarmeanlæg og el-opvarmningssystemer.This invention relates to a stoker stove for wood pellets and similar types of solid fuel in pelleted or granulated form. The stoker stove is especially designed for heating single-family homes, apartments, holiday homes and other places where an economical and environmentally friendly form of space heating is needed. The stoker stove is primarily intended as an alternative to conventional stoves of the type intended for manual burning with wood, but can in some cases also replace actual central heating systems and electric heating systems.

Kendt teknikPrior art

Fra US-patent nr 5.285.738 kendes en pillebrændeovn med et brændkammer og et særskilt pillemagasin, hvorfra en transportsnegl, der trækkes af en elektrisk gearmotor, fører pillerne fra pillemagasinet til et udløb, hvorfra de glider ud over en brændehærd. Forbrændingsluften udgøres af en primær luftstrøm til brændehærden og en sekundær luftstrøm til en frontrude.US Patent No. 5,285,738 discloses a pellet stove with a combustion chamber and a separate pellet magazine, from which a transport auger pulled by an electric gear motor leads the pills from the pellet magazine to an outlet from which they slide over a stove. The combustion air consists of a primary air stream for the fireplace hearth and a secondary air stream for a windshield.

Forbrændingsluften blæses ind i ovnkammeret v hj af to elektrisk drevne blæsere, som er indbygget i selve ovnen. Varmeydelsen reguleres ved trinvis ændring af transportsneglens omdrejningshastighed, og forbrændingsluften tilpasses automatisk den indfyrede pillemængde ved styring af blæserydelsen, dvs ved regulering af blæsernes omdrejningstal. En elektrisk eller elektronisk kontrolunit styrer de forskellige motoromdrejningstal i forhold til hinanden, idet der tilstræbes den bedst mulige forbrændingseffektivitet under de forskellige belastningsforhold, ovnen kan arbejde med. Den ved forbrændingen frembragte røggas afsuges gennem en skorsten på sædvanlig måde under udnyttelse af skorstenens naturlige træk.The combustion air is blown into the furnace chamber by two electrically driven fans, which are built into the furnace itself. The heat output is regulated by incrementally changing the speed of the conveyor screw, and the combustion air is automatically adjusted to the fired pellet quantity by controlling the fan output, ie by controlling the fan speed. An electrical or electronic control unit controls the various engine RPMs relative to each other, aiming for the best possible combustion efficiency under the different load conditions the stove can work with. The flue gas generated by the combustion is suctioned through a chimney in the usual manner, utilizing the natural features of the chimney.

Det tekniske problem der skal løsesThe technical problem to be solved

Anvendelsen af elektrisk drevne blæsere til generering af forbrændingsluftstrømmene i ovnen (primær og sekundær forbrændingsluft) er uønsket af flere grunde. For det første komplicerer og fordyrer blæserne ovnen unødigt, og for det andet betyder blæserne, at der opstår et (mindre) overtryk i ovnkammeret. Dette overtryk kan under uheldige omstændigheder -fx forårsaget af tilstoppet røgrør eller skorsten- føre til eksplosionsfare eller CO-forgiftning. Under alle omstændigheder er det at foretrække, at anvende skorstenstrækket alene til frembringelse af den primære og sekundære forbrændingsluftstrøm. Dette forbrændingsprincip giver den enkleste ovnkonstruktion og betyder samtidig, at der hersker et undertryk i ovnkammeret under driften, dvs at risikoen for ophobning af eksplosionsfarlige gasser i ovnen eller udtrængning af giftige røggasser i rummer er elimineret. Endvidere spares kostbar elektrisk energi til drift af blæserne.The use of electrically powered fans for generating the combustion air streams in the furnace (primary and secondary combustion air) is undesirable for several reasons. Firstly, the fans complicate and expensiveen the oven unnecessarily, and secondly, the fans mean that a (minor) overpressure occurs in the oven chamber. This negative pressure can, under adverse circumstances - for example caused by clogged flue or chimney - lead to explosion hazard or CO poisoning. In any case, it is preferable to use the chimney vent alone to generate the primary and secondary combustion air flow. This combustion principle gives the simplest furnace construction and at the same time means that there is a negative pressure in the furnace chamber during operation, ie the risk of accumulation of explosive gases in the furnace or the emission of toxic flue gases in rooms is eliminated. Furthermore, precious electrical energy is saved for the operation of the fans.

Når skorstenstrækket alene skal generere de primære og sekundære forbrændingsluftstrømme gennem ovnen er det et problem at starte ovnen op fra kold tilstand, dvs med kold skorsten. I denne situation, hvor skorstenstrækket er lavere end under normal "varm” driftstilstand, vil der slå røg ud fra ovnen. Dette er naturligvis ikke acceptabelt. Formålet med den foreliggende opfindelse er netop at anvise en pillebrændeovn af den omhandlede blæserfri type, hvor dette problem er løst.When the chimney draft alone has to generate the primary and secondary combustion air flows through the stove, it is a problem to start the stove from a cold state, ie with a cold chimney. In this situation where the chimney draft is lower than under normal "hot" operating conditions, smoke will emit from the furnace. This is of course not acceptable. The object of the present invention is precisely to provide a pellet stove of the present fan-free type, where this problem is solved.

? DK 97 00348 U3? DK 97 00348 U3

Den nye teknikThe new technique

Det nye ved opfindelsen består i, at der i ovnens røgaftrækskanal (røgkammeret) mellem brændkammeret og skorstenen er indsat et system af ledeplader, som dirigerer røggasserne på en sådan måde, at den effektive røgkanallængde øges samtidig med, at røgen tvinges til at passer en i ovnen fremad- og til siderne rettet konvektionskappe for afgivelse af mest mulig varme til omgivelserne inden røgens udledning gennem skorstenen. Ledeplademe selv eller en i tilslutning til ledeplademe indsat spjældplade er indstillelig ved forskydning eller svingning mellem to yderstillinger, hvor den ene yderstilling svarer til den normale driftsstilling, hvor røgen dirigeres gennem konvektionskappen som beskrevet, og hvor den anden yderstilling er en såkaldt by-pass stilling, hvor ledeplademe, resp. spjældpladen frigiver en åbning eller passage i røgkammeret, som forbinder brændkammeret direkte med skorstenen, således at røgen i denne stilling kan strømme direkte fra brændkammeret til skorstenen, dvs udenom konvektionskappen.The new feature of the invention is that in the furnace smoke extraction duct (the smoke chamber) between the combustion chamber and the chimney is installed a system of baffles which directs the flue gases in such a way that the effective smoke duct length is increased while forcing the smoke to fit one the stove forwards and sideways convection sheath to deliver as much heat as possible to the surroundings before the smoke discharge through the chimney. The guide plates themselves or a damper plate inserted in connection with the guide plates are adjustable by displacement or oscillation between two outer positions, where one outer position corresponds to the normal operating position, where the smoke is routed through the convection sheath as described, and the other outer position is a so-called by-pass position. , wherein the baffles or the damper plate release an opening or passage in the smoke chamber which connects the combustion chamber directly to the chimney so that the smoke in this position can flow directly from the combustion chamber to the chimney, i.e. outside the convection sheath.

Den tekniske virkningThe technical impact

Ved at anvende den ovenfor nævnte nye teknik i forbindelse med den kendte teknik er det muligt at dirigere røggasserne udenom konvektionskappen under ovnens opstart, dvs så længe skorstenen og ovnen endnu er kold og hvor trækforholdene derfor er utilstrækkelige til at hindre røgudslag. Røggasserne kan følgelig strømme direkte fra brændkammeret op/ud i skorstenen under forhold, hvor strømningsmodstanden er reduceret til et minimum. Man undgår på den måde, at der opstår røgudslag i rummet. Omstillingen af røgledeplademe mellem optændingsstillingen (bypass-stillingen) og driftsstillingen sker automatisk v hj af en elektrisk dréven spjældmotor eller lignende motoriseret drivanordning. Stillingen bestemmes af ovnens centrale styring. Alternativt kan ovnen indrettes til manuel omstilling, i hvilket tilfælde ledeplademe forsynet med et udvendigt betjeningsgreb.By using the above-mentioned new technique in connection with the prior art, it is possible to route the flue gases outside the convection hood during the oven start-up, ie as long as the chimney and oven are still cold and where the draft conditions are therefore insufficient to prevent smoke discharge. Consequently, the flue gases can flow directly from the combustion chamber up / out into the chimney under conditions where the flow resistance is reduced to a minimum. This prevents smoke from escaping into the room. The switching of the flue plates between the ignition position (bypass position) and the operating position is done automatically by an electrically driven damper motor or similar motorized drive device. The position is determined by the central control of the oven. Alternatively, the stove can be arranged for manual adjustment, in which case the baffles are provided with an external control handle.

Problemerne i forbindelse med optændingen af en ventilatorløs fastbrændselsovn af den her omhandlede type er til fulde løst med røgkammer-reguleringen ifølge opfindelsen. Pillebrændeovnen ifølge opfindelsen udmærker sig endvidere ved at være teknisk ukompliceret, ligesom ovnen forener de bedste egenskaber ved en traditionel brændeovn (undertryksovn) med de fordele, et moderne stokerfyr indebærer i henseende til fuldautomatisk drift, effektiv forbrænding og stort effektreguleringsområde.The problems associated with igniting a fanless solid fuel stove of the type herein are fully solved by the smoke chamber control of the invention. The pellet stove according to the invention is furthermore characterized by being technically uncomplicated, just as the stove combines the best properties of a traditional stove (suppression oven) with the advantages of a modern stoker stove in terms of fully automatic operation, efficient combustion and large power control range.

Frembringelsen og specielt fordelagtige udførelsesformer og detaljer ved denne forklares nærmere i enkeltheder i det følgende under henvisning til figurerne på tegningen.The invention and particularly advantageous embodiments and details thereof are explained in more detail below with reference to the figures in the drawing.

FigurfortegnelseList of Figures

Fig. 1 viser et lodret snit gennem en pillebrændeovn ifølge opfindelsen, med røgkammer-reguleringen indstillet til bypass, fig. 2 samme snit vist med røgkammerreguleringen indstillet til normal drift, dvs hvor røggasserne dirigeres omkring ovnens fremad- og til siderne vendende konvektionskappe, og fig. 3 et forstørret tværsnit, der viser ovnens forskellige lufttilgangskanaler med tilhørende spjældreguleringer i skematisk snitbillede.FIG. 1 shows a vertical section through a pellet stove according to the invention, with the smoke chamber control set for bypass; FIG. 2 shows the same section shown with the smoke chamber control set for normal operation, ie where the flue gases are routed around the oven's forward and lateral convection casing, and FIG. 3 is an enlarged cross-sectional view showing the various air inlet ducts of the furnace with associated damper controls in schematic sectional view.

Udførelseseksempler I den på tegningen viste udførelsesform består stokerbrændeovnen i det væsentlige af et brændkammer 1, en potteformet hærd 2, et askekammer 3, et pillemagasin 4 med 3 DK 97 00348 U3 indfyringstransportsnegl 5, et pilleudløb 6 og et røgkammer 7 med aftræksrør 8, som er sluttet til en ikke vist skorsten. Hærden 2 har ristebund beregnet som tilgang nedefra for primær forbrændingsluft, og er forsynet med et antal åbninger 9 i siden beregnet som tilgang for sekundær forbrændingsluft. Brændselspilleme afleveres fra udløbsslidsken 6 direkte i hærden, hvor forbrændingen finder sted. Asken falder ned gennem risten i bunden af hærden og opsamles i en ikke vist askeskuffe i askekammeret 3.EXAMPLES In the embodiment shown in the drawing, the stoker stove consists essentially of a combustion chamber 1, a pot-shaped hearth 2, an ash chamber 3, a pellet magazine 4 with 3 firing conveyor screw 5, a pellet outlet 6 and a smoke chamber 7 with a stove chamber 8, is connected to a chimney not shown. The hearth 2 has a grate floor intended as a bottom-up approach for primary combustion air, and is provided with a number of openings 9 in the side intended as an approach for secondary combustion air. The fuel pellets are delivered from the outlet slit 6 directly into the cure where the combustion takes place. The ash falls down through the grate at the bottom of the cure and is collected in an ash tray not shown in the ash chamber 3.

De ved forbrændingen udviklede røggasser strømmer fra brændkammeret 1 op i røgkammeret 7 via en passage 10 bagerst i ovnkammeret. Adskillelsen mellem brændkammeret og røgkammeret udgøres af en skråtstillet, varmefast ledeplade 11.1 afstand over denne ledeplade er i hver side af røgkammeret 7 indrettet et sæt vandrette ledeskinner 12, der danner understøtning for et keglestubformet legeme 13, hvis funktion er at dirigere røgen i selve røgkammeret. Keglelegemet 13 er anbragt på en vandret plade 14, som igen hviler på en ramme bestående af to parallelle sideprofiler 15. Disse er forskydeligt lejret på de to nævnte ledeskinner 12, således at keglelegemet kan forskydes mellem en forreste stilling (fig. 1) og en bagerste stilling (fig. 2). Keglelegemet 13 er åben opadtil, og omslutter med denne åbning delvis røgaftræksrøret 8, hvilket er forlænget et kort stykke ned i selve røgkammeret.The flue gases generated by the combustion flow from the combustion chamber 1 into the smoke chamber 7 via a passage 10 at the rear of the furnace chamber. The separation between the combustion chamber and the smoke chamber is constituted by an inclined, heat-resistant baffle 11.1 spaced above each baffle is a set of horizontal guide rails 12 on each side which provide support for a cone-shaped body 13 whose function is to direct the smoke into the flue chamber itself. The cone body 13 is arranged on a horizontal plate 14 which in turn rests on a frame consisting of two parallel side profiles 15. These are slidably mounted on the two mentioned guide rails 12, so that the cone body can be displaced between a front position (Fig. 1). rear position (fig. 2). The cone body 13 is open upwardly, and with this opening partially encloses the smoke exhaust pipe 8, which is extended a short distance down into the smoke chamber itself.

Når ovnen tændes op er keglelegemet 13 anbragt i den forreste stilling. I denne stilling frigiver bundpladen 14 og keglelegemet selv en lodret passage 16 bagerst i røgkammeret, hvilken passage danner en direkte forbindelse mellem brændkammeret 1 og røgaftræksrøret 8, således at røgen i denne stilling kan strømme uhindret op i skorstenen. Når ovnen og skorstenen er varmet op, og trækforholdene derfor svarer til normale driftsforhold, skydes keglelegemet 13 bagud. Derved blokeres passagen 16, og røggasserne tvinges nu af keglelegemet til at strømme op langs indersiderne af røgkammerets 7 front- og sideflader 17. Ved toppen af keglelegemet 13 tvinges røgen nedad ind i selve keglelegemet, og derfra op igen i røgaftræksrøret 8. Røgens strømningsretninger er angivet med pile i fig. 2. Ovnens front- og sideflader fungerer herunder som konvektionskappe, der medvirker til nedkøling af røggasserne og dermed til ovnens gode varmeydelse og optimale termiske virkningsgrad. Indstillingsmekanismen til keglelegemet 13 er ikke vist på tegningen.When the oven is turned on, the cone body 13 is positioned in the forward position. In this position, the bottom plate 14 and the cone body itself release a vertical passage 16 at the rear of the smoke chamber, which provides a direct connection between the combustion chamber 1 and the smoke exhaust pipe 8, so that the smoke in this position can flow freely up into the chimney. When the furnace and chimney are heated and the towing conditions therefore correspond to normal operating conditions, the cone body 13 is pushed backwards. The passage 16 is thereby blocked and the flue gases are now forced by the cone body to flow up along the inside of the front and side surfaces of the smoke chamber 7. At the top of the cone body 13, the smoke is forced down into the cone body itself and from there up again into the smoke extraction pipe 8. indicated by arrows in FIG. 2. The front and side surfaces of the oven function below as a convection sheath, which contributes to cooling the flue gases and thus to the oven's good heat output and optimal thermal efficiency. The adjustment mechanism of the cone body 13 is not shown in the drawing.

I fig. 3 er ovnens lufttilgangssystem vist skematisk. Forbrændingsluften indtages ved ovnens frontside gennem to hulprofiler 20 anbragt i hver side af røgkammeret 7 umiddelbart under de vandrette ledeskinner 12.1 hver side af ovnen er indrettet en anden vandret kanal 21, som leder en mindre del af forbrændingsluften til et antal luftindblæsningsåbninger 22 placeret ud for ovnkammerets frontrude 23 på inderrsiden af denne. Tilgangen af forbrændingsluft til frontruden reguleres af et fast indstillet spjæld 24 i kanalen 21,In FIG. 3, the air supply system of the furnace is shown schematically. The combustion air is taken in at the front of the furnace through two hollow profiles 20 disposed on each side of the smoke chamber 7 immediately below the horizontal guide rails 12.1 on each side of the furnace a second horizontal duct 21 is provided which conducts a smaller portion of the combustion air to a plurality of air supply openings 22 located outside the furnace chamber. windscreen 23 on the inner side of this one. The supply of combustion air to the windshield is controlled by a fixed damper 24 in duct 21,

Den resterende del af forbrændingsluften opdeles i en primær og sekundær forbrændingsluftstrøm. Den primære forbrændingsluft tilføres hærdens ristebund via et luftreguleringsspjæld 25 og askekammeret 3. Den sekundære forbrændingsluft tilføres hærdens sideåbninger 9 via et andet luftreguleringsspjæld 26 og et mellemkammer 27 (=luftfordelerkammer), som omslutter hærdens sideflader. Forbrændingsluften forvarmes inden den tilføres forbrændingszonen i hærden ved passage af diverse varmekonvektionsflader 28 på bagsiden af ovnkammeret og under passagen af luftindtagskanaleme 20. Det bemærkes, at ovnen -bortset fra røgrørstilslutningen 8- er konstrueretThe remaining portion of the combustion air is divided into a primary and secondary combustion air stream. The primary combustion air is supplied to the cure bottom grate via an air control damper 25 and the ash chamber 3. The secondary combustion air is supplied to the cure side apertures 9 via a second air control damper 26 and an intermediate chamber 27 (= air distribution chamber) enclosing the curing side surfaces. The combustion air is preheated before it is applied to the combustion zone in the cure by passing various heat convection surfaces 28 on the back of the furnace chamber and during the passage of the air intake ducts 20. It is noted that the furnace - apart from the flue pipe connection 8-

Claims

1. A stoker stove with a combustion chamber and a separate pellet magazine from which a transport auger pulled by an electric gear motor leads the pellets from the pellet store to an outlet from which they slide over a stove and where the combustion air is divided into a primary air stream. to the bottom of the stove, and a secondary air stream which is fed into the side of the stove through a plurality of apertures therein, which combustion air is preheated during passage of a convection sheath in the stove and upon contact with the outside of the stove before entering the stove itself, which occurs via automatic controlled air control dampers, characterized in that in the furnace smoke extraction duct between the combustion chamber and the chimney is inserted a system of discharge plates which directs the flue gases in such a way that the effective smoke duct length is increased at the same time as the smoke is forced to pass one in the oven and the sides directed convection sheath to provide as much heat as possible the surroundings before the smoke discharge through the chimney, and that these baffles themselves or a damper plate inserted in connection with the baffles can be adjusted by displacement or oscillation between two outer positions, one outer position corresponding to the normal operating position, where the smoke is routed through the convection casing as described, and where the second outer position is a so-called by-pass position where the baffles, or the damper plate, release an opening or passage in the smoke chamber which connects the combustion chamber almost directly to the chimney, so that the smoke can flow directly to the chimney outside the convection casing.

Stoker stove according to claim 1, characterized in that the switching of the guide plates, alternatively the damper plate between the two outer positions, is effected by an electric motor controlled by the central control of the oven.

Stoker stove according to claim 2, characterized in that the switching between the two positions (by-pass position and normal position) takes place automatically depending on different operating parameters, for example chimney temperature, oven temperature, ignition time, etc.

Stoker stove according to claim 1, characterized in that the said baffles in the smoke chamber are constituted by a generally closed, cone-shaped body mounted on a set of parallel, horizontal frame profiles, which rests on a set of corresponding rail profiles built into the the bottom of the smoke chamber so that the cone body on these rails is displaceable between a forward position (Fig. 1), where a nearly vertical passage through the smoke chamber is formed between the rear wall of the smoke chamber and the back of the cone body, which passage connects the combustion chamber and the chimney pipe directly (bypass); and a rear position (Fig. 2), with the cone body with its rear side blocking said vertical passage and instead with its front side and two side faces forcing the smoke along the inside of the front and side faces of the smoke chamber (= convection sheath).

Stoker stove according to claim 4, characterized in that said cone body is cut off as a cone stub with open top end and with the upper part of the rear side surface of the cone stub removed, so that the smoke discharge pipe of the stove is made, which is led down a short distance. in the open cone top, whereby the smoke is forced up around the upper edge of the cone stump and a short distance down into it before the smoke can escape through the exhaust pipe (provided the cone body assumes the normal operating position, Fig. 2).

Stoker stove according to claim 1, characterized in that both the primary and secondary combustion air are regulated by separate air dampers, which are automatically adjusted by electric damper motors which are controlled via the central control of the furnace.

Stoker stove according to claim log 6, characterized in that a smaller part of the air intake of the furnace is led to a series of slit-shaped air supply openings in the interior chamber behind the oven's windscreen, so that the window pane is kept clear and the amount of windscreen air is determined by the total air intake. an adjustable air distribution valve (damper valve) which is fixed under normal conditions.

Stoker stove according to claim 1, characterized in that the curing device has a pot shape and is loosely inserted into a recess for this purpose at the bottom of the furnace chamber.