DE202007011469U1 - Pellet burner for bakery ovens - Google Patents

Abstract

Pellet burners for bakery ovens, in particular deck ovens, with a burner head consisting of
- A burner head housing and
- A recorded therein grate and
- A flame outlet opening in the burner head housing and
- A pellet feed opening of any kind in the housing
characterized in that
- The flame outlet opening in one of the side walls of the combustion head
- Housing is arranged and
- In particular, the flame zone of the burner in the direction of travel
- Connects horizontally to the burner grate.

Description

I. Field of application

The The invention relates to a pellet burner for bakery ovens and a bakery oven, with a equipped with such a pellet burner.

II. Technical background

In bakeries are used there for baking ovens, which are often designed as deck ovens are in those of the baking chamber in several over each other lying individually accessible Levels is divided - because of of the high energy demand usually heated with primary energy and not with electricity to the one incurred in the conversion of primary energy into electricity Save conversion loss.

To this purpose is in a combustion chamber below the or the back rooms, the usually with a good heat holding and heat surrounding medium such as fireclay, a combustion chamber formed in which an oil or gas burner burns the respective primary energy and the This generated combustion energy heats the oven.

there Almost without exception has been oil or Gas, since these are the most widely used primary energy sources and above out for the combustion of these fuels also the necessary burner technology inexpensively and in large numbers from the field of domestic and industrial heating and only slightly adapted to the boundary conditions when used in a bakery oven got to.

One Another advantage was the burner for oil or gas very small and compact to build, especially since the feeder the fuel in a simple way through simple, thin pipes or hose lines is possible through and as well Dosage.

In recently, Time is, however, with primary fuel driven heaters, especially in the living area reinforced again renewable raw materials used, not least because of the resulting better achievable carbon dioxide balance.

Around also with biomass, especially wood, operated heaters as far as possible to be able to operate automatically as well as by means of oil or gas has long been possible is biomass, especially wood, to uniform and equal sized pellets pressed, which made of bulk material similarly easy and automated handling like liquid or gaseous fluids.

• – Schnelle und unproblematische Zündung des Brennstoffes,
• – bei Bedarf schnelle Temperaturerhöhung in der Brennstelle,
• – Schmutzfreiheit, insbesondere Staubfreiheit der Umgebung um den Brenner; hierzu insbesondere gekapselte Bauform,
• – Nachrüstbarkeit bei den in der Regel sehr langlebigen und auch teuren Bäckereiöfen in dem Raum der dort bisher für Öl oder Gasbrenner benutzt wurde,
• – kein Lagerungsraum für das Brennmaterial in unmittelbarer Nähe des Brenners, insbesondere komplizierte, enge Zufuhrwege von einer entfernten Lagerstelle zum Pellet-Brenner,
• – kaum für die Reinigung bzw. Ascheentsorgung zur Verfügung stehende Zeit des Bäckereipersonals.

The heating of bakery ovens with pellets is possible in principle, but has in practice in this application, as well as no indentation due to the specific features of a use in bakery ovens held:

• - Fast and unproblematic ignition of fuel,
• - if necessary, rapid temperature increase in the combustion station,
• - dirt-free, in particular dust-free environment around the burner; this particular encapsulated design,
• - Can be retrofitted to the generally very durable and expensive bakery ovens in the room that was previously used there for oil or gas burners,
• No storage space for the fuel in the immediate vicinity of the burner, in particular complicated, narrow supply paths from a remote storage location to the pellet burner,
• - Hardly for the cleaning or disposal of ash disposal time of the bakery staff.

Yet There is a big one Interest, bakery ovens with renewable raw materials, especially wood and thus preferably in pellet form too heat, on the one hand the reduction of the energy costs of the bakeries should serve and above but also other reasons such as the preparation of bread and other staple foods on ecological and / or biologically correct way.

III. Presentation of the invention

a) Technical task

It is therefore the object according to the invention, a pellet burner for To create bakery ovens, which fulfills the existing boundary conditions and especially in the past with oil or gas heated stoves in the existing there combustion chamber is retrofitted or one with a bakery ovens equipped with such pellet burners put.

b) solution the task

These The object is solved by the features of claims 1 and 2. advantageous embodiments emerge from the dependent claims.

A well-known pellet burner which usually comprises a burner head housing with combustion grate held therein for combustion of the pellets is further developed according to the invention in that, contrary to the known designs, the flame outlet opening is arranged in one of the side walls of the burner head housing and thereby into the special the flame zone horizontally in the direction of the combustion grate adjoins this.

in the In contrast, the flames are in a known pellet burner preferably directed upward and the air required for combustion becomes primary supplied from below and thus through the grate, while according to the invention, the combustion air above and / or below the burner grate substantially parallel strokes along the grate and thus a corresponding image of Flame zone is effected.

For one automated burner operation is required for pellet combustion burner fan necessary, with which the amount of supplied combustion oxygen varies can be an ignition device for the Starting the burner and a pellet feeder.

All three elements are arranged on the front plate of the burner head housing and thus at one of the front under the baking chamber in the combustion chamber inserted pellet burner easily accessible.

Prefers are two burner blowers present, one of which is in the space of the burner head below and one above the combustion grate can inject air, thereby the combustion process can be specifically influenced.

The Front panel of the combustion head to which these units are attached, is viewed in the top view preferably angled, taking at two blowers one each of the blowers attached to one of the flanks of the angle.

There solely because of the mechanical components for feeding the pellets, combustion in larger volumes on a grate, etc. in the reason larger space requirements for one such pellet burner exists as for an oil or gas burner, is the one hand compact, space-saving arrangement of all required components and on the one hand their nevertheless good accessibility and yet the optimal running of the combustion process is essential, around such a pellet burner under the baking chamber of a baker's oven in the there available install and use standing limited space and in particular upgrade to know.

To this purpose are with two burner blowers, for which because of the compact Dimensions preferred Radial blower be inserted, from the injection ports, on different Heights are - as above explained - the blower mounted so, that their housing at a high-lying injection opening hang down and at a low-lying injection opening stick up to over the visible in the front view marginal dimensions of Fontplatte not stand out.

there will the igniter, which is usually a hot air blower, with a curved in the direction of rust within the combustion chamber continuing Snorkel made of heat-resistant Material, also mounted on the front panel, preferably above the injection opening for burner blower, from which out of the blower protrudes downwards.

there has the hot air blower, which as detonator serves, an air supply line, to the rear, d. H. free to the outside outstanding end of the hot air blower arranged is that back in a bow leads to the interior of the burner head and is in contact with it and draws air from there.

Thereby becomes after turning on the hot air blower no cold ambient air but already sucked in preheated air, whereby the necessary ignition temperature achieved at the pellets faster.

In the pellet feeder, the most over one or more augers is realized is at a short distance in front of the combustion chamber a Rotary valve on ordered, on the one hand the quantitatively defined feed of pellets in the combustion chamber and on the other hand because of the possible dense Construction of the rotary valves serves as a non-return valve to to prevent flame or embers through the transport pipe in the transported fuel or even the storage container for kiln recoils, for example with deflagrations in the combustion chamber.

ever after how far the rotary valve from the pre-opening for fuel the combustion chamber is removed and how high it is above this move the pellets from the rotary valve to the combustion chamber either automatically by means of Gravity or by means of a conveyor, for example, a screw conveyor.

As well The pellets are also transported to the rotary valve with a conveyor like a screw conveyor transported.

there has a very easy to handle conveyor one of a flexible plastic tube tightly wrapped wire spiral proved extending along the entire desired transport route in the Plastic tube extends and as well as this regard a lateral deflection is flexible.

One Such transport hose can while avoiding too tight bending radii laid in almost any direction, inclines and bends without changing the direction of straight augers necessary intermediate container, Intermediate funnel or similar needed become.

For the automated Operation of such a pellet burner is of course a control necessary, which is preferably operated electrically.

A Such control controls the speed of the burner fan (s) Switching the igniter on and off and thus the switchover of ignition on continuous operation and the rotation of the rotary valve and where appropriate also the leading to and from the rotary valve conveyors namely preferably only in dependence from the specified target temperature of the furnace.

A Particularly simple control results when the controller exclusively the speed of the fan (s) on the one hand and the switching on and off of the ignition device on the other and controls the rotation of the rotary valve.

For the controller In the firing process, the burner further comprises an oxygen sensor in the flame or exhaust gas range, whose measured values are additionally indicated as Input size - next to the set target temperature - serve for the control.

Around Such a burner below the oven in a baker's oven in the there available operating and especially retrofitting there can, have to on the one hand the dimensions of the burner are kept so compact, that he is there despite the need for horizontal flame formation and good accessibility to accommodate the mechanical components.

Especially should the pellet burner while a bakery oven, such as a Deck oven, to be used, whose back rooms of a heat-storing Layer are surrounded, in which liquid-filled, with Water filled closed ring pipe is present, it distributes the other Bottom of the multi-storey Backraumes supplied heating energy evenly over the circumference of the oven and because of the running between the individual baking chambers lines evenly on all baking rooms.

The Ring pipe is so embedded in the wall material and enclosed by this, that they are not the direct flame action of the burner is exposed.

• – Kurze Aufheizphasen
• – Energie- und Kostenersparnis, ökologisch und ökonomisch
• – Einfache Bedienung und Aschenentleerung
• – Beste Backeigenschaften

The combination of a pellet burner especially with such a ring tube furnace gives additional advantages:

• - Short heating phases
• - Energy and cost savings, ecological and economical
• - Easy operation and ash removal
• - Best baking properties

Around that at intervals necessary cleaning and other maintenance work on the burner quickly and easily perform to be able to the pellet burner is stored on rollers and in the whole, d. H. including the Brennkopfes and all leading to the burner conveyors from the Removable oven, especially just forward out of the oven.

This has the advantage that the rest Sides of the oven for other purposes available For example, the stove can be placed with one side directly to one Be set on the wall or behind the oven can set up other units become.

In front especially when retrofitting a bakery oven with such a pellet burner will be available in the standing combustion chamber inserted and fixed a slide-in frame among other things the guides for inserting the burner offers and also a front cover may have the front surface as far covers that after pushing the front plate of the Pellet burner completely is closed, which is not the visible front of the Oven forms by an additional Aperture is formed while also the front side of the font plate of the burner outstanding Components are already behind this panel.

component the insertion frame may in particular be a slide-in plate, Stable enough to carry the torch and heat resistant enough, especially made of metal, around those occurring in the combustion chamber Temperatures without major deformation to cope.

One the above-mentioned arranged behind the furnace units as mentioned above For example, a heat exchange through which the flue gases, d. H. Exhaust gases of the effluent from the combustion chamber combustion gases be passed through to this before escaping through a chimney in addition to the environment Heat too withdraw to use them.

By means of such a heat exchange, for example, the entire space heating in the rest of the building in which the bakery is located, operate ben as well as their hot water needs.

In Times when less heat energy or hot water heating is needed as through the heat exchanger delivered, this gives its heat in a heat storage starting with the heat exchanger via a Heat exchanger circuit communicates.

Indeed The temperature of the exhaust gases in a subsequent chimney must not fall below a threshold to avoid condensation, because this aggressive acids on the walls knock down the chimney and destroy it with time. Therefore is also trying the heating phase of such a burning system preferably to keep short, in the nature of the temperature in the fireplace is still below this threshold.

Around To achieve this is preferably a bypass for the flue gases around the heat exchanger provided over which these the heat exchanger without major temperature loss can happen especially for the heating phase desired is.

controlled becomes the path of the flue gas over a flap that allows the access of the flue gases optionally in the bypass line or in the heat exchanger free, with this flap of the signals of a temperature sensor in the exhaust system, preferably downstream, by bypass and heat exchanger is controlled.

Of the heat exchangers itself preferably consists of a bundle of parallel, side by side arranged pipes, preferably in terms of their cross-sections offset from one another are the greatest possible contact with the be called Allow flue gases.

Around the heat from the heat exchanger in the downstream consumer cycle, in particular the heat storage, to be able to regulate and over here independently from the current temperature level in the combustion chamber, the exhaust gas temperature, is in the heat exchanger circuit arranged a regulated pump, preferably only with the help the temperature sensor is regulated in the exhaust pipe.

there sets the pump at the earliest then, if the exhaust gas temperature and / or the temperature in the heat exchanger is above a predetermined threshold.

With Such a device can also be a comparatively simple control method the operation of such a baker's oven in an automatic manner, e.g. only by means of a temperature sensor in the oven area, the controller no more than the speed of all blowers of the pellet burner, the and switching off the traction device and the pellet replenishment, in particular the rotation of the cell wheel, controls.

there needed the ignition device only two blowers to turn on and off, reducing the transition from ignition operation on full load by means of the control of the other two parameters is achieved.

there At full load, the primary blower becomes blowing in above the grate always operated while the secondary fan in particular dependent on the measured residual oxygen in the exhaust gas is controlled.

Claims (25)

Pellet burner for bakery ovens, in particular deck ovens, with a combustion head, comprising - a combustion head housing and - a grate held therein and - a flame outlet opening in the burner head housing and - a pellet feed opening of any kind in the housing, characterized in that - The flame outlet opening is arranged in one of the side walls of the combustion head - housing and - in particular the flame zone of the burner in the direction of - the burner grate connects horizontally to this. Bakery floors oven with a pellet burner, in particular according to one of the preceding Claims, thereby marked that - of the Combustion chamber in which the burner blows in the flame, below the baking chamber located and - of the or the baking chambers of a liquid-filled, in particular water-filled enclosed ring tube are surrounded. Oven according to claim 2, characterized in that the ring pipeline without direct contact with the flame of the burner is embedded in the wall material of the furnace. Oven according to one of the preceding claims characterized characterized in that the entire pellet burner, including burner blower, burner ignition and Pellet insertion is arranged below the baking chamber and in particular no over the front edge of the baking space protrudes. Oven according to one of the preceding claims characterized characterized in that the pellet burner sits on rollers and off the oven can be moved out, in particular to the front can be moved out of the oven. Oven according to one of the preceding claims characterized characterized in that the combustion chamber, in particular on the back of the furnace a heat exchanger downstream, which flows through the exhaust gases and the deprived energy one with the heat exchanger related heat storage forwards. Oven according to one of the preceding claims characterized characterized in that the heat exchanger arranged in a horizontal portion of the flue gas line bunch from parallel to each other horizontally or vertically extending tubes consists. Oven according to one of the preceding claims characterized characterized in that the cross sections of the individual tubes offset are arranged to each other, ie in the flow direction of the flue gases a pipe behind the gap between two previous pipes is arranged. Oven according to one of the preceding claims characterized characterized in that the heat exchanger a bypass line, the inlet of which alternately with the inlet to the heat exchanger can be closed by means of an automatic controlled Flap and depending from the exhaust gas temperature. Oven or burner according to one of the preceding claims characterized in that the burner at least one burner blower, at least an ignition device and having a pellet feed, all of which are arranged on the front panel of the burner head housing are. Oven or burner according to one of the preceding claims characterized in that there are two burner blowers, of which one in the space of the burner head below the burner grate (primary blower) and one in the space above the burner grate (secondary blower) respectively blown in a horizontal direction. Oven or burner according to one of the preceding claims characterized in that the front plate of the burner head in viewed from the top is considered angled and one of each two blowers is mounted on one of the flanks of the angle. Oven or burner according to one of the preceding claims characterized in that the burner blowers are radial blowers one of them, in particular the primary fan, extends from the injection opening mounted hanging down and others, especially the secondary blower, project from the injection port extending to the top. Oven or burner according to one of the preceding claims characterized in that the ignition device is a hot air blower, which opens in the front panel and in the direction of the grate, in particular by means of a downward cranked snorkel, extended is. Oven or burner according to one of the preceding claims characterized in that the ignition device, in particular the hot air blower, above the injection opening is mounted, from which a fan hangs down. Oven or burner according to one of the preceding claims characterized in that the hot air blower has an air supply line communicates with the interior of the combustion head and from there Air sucks. Oven or burner according to one of the preceding claims characterized in that in the pellet feed a rotary valve for supply control and non-return valve is arranged. Oven or burner according to one of the preceding claims characterized in that a first pellet transport screw the pellets are transported from the rotary valve to the combustion grate. Oven or burner according to one of the preceding claims characterized in that a second conveyor, in particular second screw conveyor, the pellets transported to the rotary valve. Oven or burner according to one of the preceding claims characterized in that the burner can be retrofitted in bakery ovens, in particular deck ovens, in particular with the aid of a suitable insertion frame to be installed in the combustion chamber there, including the guides for the extendable Burner includes. Oven or burner according to one of the preceding claims characterized in that there is a control that the Speed of the fan (s), the switching of ignition on continuous operation, rotation of the rotary valve and the screw conveyor controls, in particular for ignition, rotation the rotary valve and the screw conveyor controls in dependence from the specified target temperature. Oven or burner according to one of the preceding claims characterized in that the burner is an oxygen sensor in the flame or exhaust area, in particular - via the controller the material supply, in particular the rotary valve, controls. Oven or burner according to one of the preceding claims characterized in that in the exhaust path, a temperature sensor available is who the bypass flap of the heat exchanger controls. Oven or burner according to one of the preceding claims characterized in that the furnace comprises a bottom rail plate, on whose bottom rails the burner rollers can be rolled and the bottom rail plate in particular part of the insertion frame is. Oven or burner according to one of the preceding claims characterized in that the heat exchanger circuit of the exhaust gas stream includes a pump that communicates with the temperature sensor and is only activated above a predetermined target temperature in the heat exchanger circuit and / or in the exhaust.