DE102006014633B4 - heating burners - Google Patents

Abstract

A heating burner for a heating system with a control device (10), with at least one primary sensor for detecting heating power of the heating burner and with actuators having an igniter (50) for igniting fuel, an air conveyor for conveying combustion air and a fuel conveyor (20) for conveying from fuel to the ignition device (50), wherein the delivery rate of the fuel delivery device (20) and / or air conveying device is substantially freely adjustable and the control device (10) adjusts the actuators such that the fuel is ignited in ignition intervals (tZ) and for a adjustable combustion interval (tB) burns, wherein the heating power by the control device (10) over the length of the combustion interval (tB) in the respective ignition interval (tZ) is controllable, characterized in that the fuel is a liquid fuel and the ignition device (50) a Preheating (40) comprising the Bre fuel heats up to ignition temperature, wherein the control device (10) adjusts the actuators such that the fuel in constant preset ignition intervals (tZ) ...

Description

The present invention relates to a heating burner for a heating system.

Heating burners are used for a variety of applications. They are used to heat buildings, surfaces and liquids, whether for everyday use or, for example, for a swimming pool. Even though the requirements that arise in the individual application areas sometimes differ greatly, a requirement for the burner is common to all application scenarios. It is necessary to set a certain required temperature at any time in the system to be heated, wherein the temperature can vary greatly over time, but the reaction time of the heating burner should be short. To make matters worse, the system often reacts lazily to the heating of the burner.

To meet this requirement, most of the heating burners have an input that determines the desired setpoint temperature and at least one sensor that determines the actual temperature in the system. Internal control methods try to control the heating burner or its combustion flame so that the actual temperature corresponds as closely as possible to the setpoint temperature. As already mentioned, it should be noted in this regulation that the reaction time of the entire heating system is relatively sluggish, the setpoint requirements constantly vary and an efficient and maintenance-free heating is required. A high efficiency of the heating burner and a low-emission and soot-free burning of the fuel used in each case is required in the commercial heating burners.

• – das intermittierende Verfahren
• – das modulierende Verfahren

Essentially, the regulation of heating burners distinguishes between two methods, which are used either individually or in combination:

• - the intermittent procedure
• - the modulating procedure

In intermittent control, an area is set around the desired setpoint temperature. During combustion, the heating burner only knows two statuses. In a burning status, unregulated fuel is burned and heat energy is produced. In a switched-off state, no fuel is burned, additional heat energy is not passed on to the heating system. If the actual value falls below the lower interval limit of the setpoint, the heating burner is ignited and burns until the actual value exceeds the upper limit of the interval. The burner is then switched off again and remains in this state until the actual value specifies that a renewed ignition is necessary. An actual temperature curve, as it usually arises in a heating burner with an intermittent method can the 4a be removed. A corresponding heating system is in the introduction of EP 0 387 703 B1 described. The intermittent method has the disadvantage that in order to ensure a low-emission and the calorific value of the fuel optimally exploiting combustion, the interval length is relatively generous and additionally due to the possibly long reaction time hysteresis occurs. Therefore, there is a strong over- and under-regulation that affects the quality and efficiency of the system. On the one hand, only the heat energy that is really desired is rarely delivered, and on the other hand, the excessive overdriving of the actual power increases the heat loss in the piping systems and leads to wear (eg calcification).

The modulating process regulates the heating power in the same way as the actual value of the temperature in the system. For example, the fuel supply can be regulated within the scope of a control range. A modulating heating system is discussed in the introduction of CH 692 757 A5 described. However, since the control range is finite, the intermittent procedure must be changed if the control range is exceeded or undershot. The disadvantages mentioned in relation to the intermittent method appear the same, if not stronger.

Also, it is difficult in this method, the control variables (for example, air supply and fuel supply) to regulate so that over the entire control range comes to an efficient, low-emission combustion.

The DE 35 24 230 A1 describes a control device for a room thermostat. Here are the distances of individual switching cycles, in which a burner heats, and their length varies. Further heating burners are from the DE 82 21 965 U1 and the EP 1 008 807 B1 known.

Based on this prior art, it is an object of the present invention to provide a heating burner, which provides a desired burning performance in an efficient and low-emission manner.

The object is achieved by a heating burner according to the features of claim 1.

According to the invention the object is achieved by a heating burner for a heating system with a control device, with at least one primary sensor for detecting a heating power of the heating burner and with actuators having an ignition device for igniting fuel, an air conveying device for conveying combustion air and a Fuel delivery device for conveying fuel to the ignition device, wherein the delivery rate of the fuel delivery device is substantially freely adjustable and the control device adjusts the actuators such that the fuel is ignited in periodically recurring ignition intervals and burns for an adjustable combustion interval, wherein the heating power through the control over the length of the firing interval can be regulated in the respective firing interval.

A central idea of the invention is thus that the control device ignites the fuel at regular intervals and operates a combustion flame at a predefined power. The heating power produced by the heating burner is only regulated by the respective burning time, ie the adjustable burning interval. In essence, the controller need only distinguish three phases within a firing interval, an initialization phase in which the firing power is ramped up to a predefined value, a constant firing phase in which the firing power is maintained at a constant value, and a stop phase in which the firing Burning power is reduced back to almost zero.

The control device can thus be designed so that it optimally operates the actuators for these three phases in such a way that an efficient combustion of the fuel is ensured. In the control device of the actuators is particularly the regulation of the fuel-air ratio decide, therefore, according to the invention, at least the flow rate of the fuel conveyor freely adjustable. By precisely controlling the heating power, there is less heat loss in the entire heating system, especially in the pipes.

Preferably, the ignition intervals are less than or equal to 60 seconds. A fast response of the heating burner is thus ensured and the actual output of the heating burner adapts optimally to the setpoint output. An overshoot and undershoot the heating power can be avoided.

According to the invention, the fuel is a liquid fuel, in particular rapeseed oil or other natural oils.

It is advantageous for the actuators to comprise a motor which sets a truncated cone in rotational movements about its longitudinal axis such that fuel introduced into the truncated cone via an inlet opening escapes at an outlet opening due to the centrifugal force and is atomized. The truncated cone is thus a cylindrically shaped tube through which at the inlet, where the tube has the smaller diameter, fuel is introduced, which is driven due to the rotation in the direction of the outlet opening. If the truncated cone is driven fast enough, the fuel emerging at the outlet opening will be atomized due to the centrifugal forces acting on it. Long-chain liquid fuels crack the molecular chains.

Preferably, the ignition device comprises a heat return, which is made of thermally conductive material and emits heat occurring in a combustion of the fuel to nachströmenden fuel. The heat recovery may be, for example, a rod, an internally-powered, motor-driven impeller, or other construction suitable for dissipating some of the heat generated during the combustion of the fuel. This derivation takes place in the direction of a fuel supply line. Thus, the inflowing fuel can be heated to just below the ignition temperature.

It is also conceivable to preheat the inflowing fuel to a temperature above the respective ignition temperature, so that it comes directly to the ignition of the fuel in the supply of air.

Preferably, this heat recovery is at least partially arranged in the interior of the above-described hollow cylinder, the outlet opening towering. Thus, the heat generated at the outlet opening of the truncated cone is transported away in the direction of the inlet opening of the truncated cone. Since there is a lack of oxygen inside the truncated cone, the fuel can be preheated to temperatures above the ignition point. Only at the exit from the truncated cone through the outlet opening it comes to the inflammation.

In particular, for igniting the fuel in the initialization interval or the initialization phase, the ignition device according to the invention comprises a preheating, which heats the fuel to ignition temperature. Since there is not enough burning power outside the firing interval to sufficiently preheat the inflowing fuel in the initialization interval, external preheating should be provided. Preheating can be ohmic or inductive. It is crucial that the preheating is controllable by the control device and is regulated according to the phases.

Preferably, the preheating comprises a heating coil which surrounds the truncated cone. Thus, the fuel is heated indirectly via the truncated cone.

Preferably, the control device is designed such that it controls the fuel delivery device and the air conveyor such that is present during the firing interval, preferably in an initialization and initialization phase and a stop interval or stop phase, a substantially constant air-fuel ratio at the ignition device. The air-fuel ratio can be chosen so that the most efficient, especially soot-free combustion of the fuel is ensured. Because of this type of intelligent control device, the heating burner rarely needs servicing and ensures efficient fuel utilization despite the frequent relight.

It is advantageous if the heating burner has an air flow sensor for determining the delivery rate of the air delivery device. The control device can thus not only control the air required for igniting and burning the fuel according to a preset mode, but also regulate it as needed. Apart from air flow sensors, various temperature sensors for both fuel and air as well as flow sensors for the flow rate of the fuel can be provided.

The control device preferably adjusts the actuators, in particular the fuel pump or conveying device, and the air conveying device in such a way that a pilot flame is present outside the combustion interval. A reignition of the fuel is thus not necessary and a sufficiently powerful device for this need not be provided. By holding a pilot flame can further be avoided an explosive ignition of the fuel in the initialization phase. The pilot flame may also serve to provide heat for preheating fuel and thus ensure efficient burning of the fuel throughout the ignition interval.

Preferably, the control device is designed such that, in order to supply the pilot flame, it controls the fuel pump outside the firing interval so that less than one percent, preferably less than one per thousand, of the maximum delivery rate of the fuel pump is conveyed.

Preferred embodiments of the invention will become apparent from the dependent claims.

Hereinafter, preferred embodiments of the invention will be explained in more detail with reference to figures. Show here

1a a block diagram of a control device of a heating burner according to the invention with associated actuators and sensors;

1b individual sensors of the control device 1a ;

2 the functional arrangement of the individual components of a heating burner according to the invention;

3 the structure of a heating burner according to the invention;

4a a time-temperature diagram of a heating burner with intermittent control;

4b a time-temperature diagram of a heating burner according to the invention;

5a the burning power of a heating burner according to the invention over several ignition intervals;

5b the burning power of a heating burner according to the invention over a first ignition interval; and

5c the burning power of a heating burner according to the invention over a second ignition interval.

In the following description, the same reference numerals are used for the same and the same parts acting.

An inventive heating burner can in the 1a include components shown. A central unit of the heating burner forms the control device 10 , This is connected to a plurality of actuators, in the present example an ignition device 50 , a nebulizer 70 , an air conveyor 80 , a fuel conveyor 20 , a cracker device 30 and a preheater 40 , The control device 10 of the heating burner regulates or controls the respective actuators in such a way that an efficient burning, ignition and down regulation or extinction of the fuel is ensured. Efficient in this case means that the calorific value of the fuel is utilized optimally while a low-pollution and soot-free combustion is ensured, so that maintenance of the heating burner according to the invention is rarely necessary. For the control of the actuators, the control device receives 10 Signals from multiple sensors 60 , These sensors 60 comprise at least one primary sensor, by means of which the control device can determine an actual temperature of the system to be heated.

In the present heating burner, this primary sensor is a heating water temperature sensor 65 determining the temperature of a heating circuit heated by the heating burner. The control device is designed such that it can determine a difference between the actual temperature and a setpoint temperature and regulates the actuators in such a way that this difference is as small as possible at any point in time.

Since the heating burner according to the invention has a very low number of states namely the ignition of fuel, the burning of fuel, the extinguishing of the combustion flame or the reduction of the combustion flame and an idle without combustion flame or with a reduced combustion flame, is a pre-configuration of the control device 10 conceivable. This preconfiguration determines, for each of the states mentioned, optimal parameters for controlling the actuators. In the in 1a and 1b illustrated embodiment include the sensors 60 additionally an air temperature sensor 61 , an airflow sensor 62 , a fuel temperature sensor 63 and a fuel flow sensor 64 , The fuel flow sensor 64 and the airflow sensor 62 deliver to the controller 10 Signals that allow this, conclusions about the performance of the fuel conveyor 20 and the air conveyor 80 to draw. The air temperature sensor 61 and the fuel temperature sensor 63 help the controller 10 the preheating 40 to regulate so that it comes to an optimal combustion of the fuel.

A combustion chamber according to the invention 1 includes as schematically in 2 illustrated two leads. The one, a fuel line 21 leads the combustion chamber 1 Fuel to, the other an air line 81 provides the necessary oxygen or the necessary oxidizing agent for the combustion. In the present embodiment, the fuel to be combusted is rapeseed oil. The fuel is in a fuel tank 24 stored and over the fuel line 21 by means of a fuel conveyor 20 to the combustion chamber 1 promoted. Here, the crude oil passes a preheating 40 , which heats the fuel for easier ignition and a cracker 30 that processes the fuel. Another functional unit, a nebulizer 70 , is directly at the combustion chamber 1 provided and mixes the fuel with the over the air line 81 supplied air. An ignition device 50 ensures the ignition of the air fuel mixture in the combustion chamber 1 ,

It can work on a separate ignition device 50 inside the combustion chamber 1 be waived if the preheater 40 the fuel is heated to a temperature above the specific ignition temperature. When the fuel is mixed with the air, it ignites spontaneously. The preheater 40 So takes over the functionality of the ignition device 50 ,

The 3 shows the structure of in 2 schematically illustrated embodiment of the heating burner according to the invention. The air line 81 is in the form of a generously dimensioned tube. At a point of the air line 81 enters the fuel line 21 through the outer wall of the air duct 81 and continues inside the same. The fuel line 21 and the air line 81 are still separated from each other.

A first opening of the fuel line 21 flows into the fuel tank 24 from which the fuel to a second opening of the fuel line 21 is encouraged. This second opening closes inside the air duct 81 airtight with an inlet opening 35 a truncated cone 32 from. The truncated cone is from a motor, not shown 37 driven so that the over the inlet opening 35 entering fuel inside the hollow truncated cone 32 due to the centrifugal force to an outlet opening 36 is promoted, the entrance opening 35 but due to the shape of the truncated cone 32 has a larger diameter. By the engine 37 Applied centrifugal force is in the truncated cone 32 introduced crude oil at a spoiler edge along the exit opening 36 both mechanically cracked as well as with the over the air line 81 brought up, the truncated cone 42 ambient air mixed. The motor 37 and the truncated cone 32 thus form the funktonal units of the atomizer 70 and the cracker 30 from the 1a , The truncated cone 32 is loose from a heating coil 44 surround. This heats not only the air surrounding the truncated cone but also the truncated cone 32 itself. Since the truncated cone 32 is made of thermally conductive material, the heat energy of the heating coil 44 to the fuel inside the truncated cone 32 passed. The heating coil 44 So it has dual functionality and heats both air and fuel.

The preheated fuel ignites as soon as it is mixed with the air. The resulting heat output is delivered not only as heating power of the heating burner but to a small extent via a heat return 42 , which extends in the form of a metal rod inside the truncated cone, to the inflowing fuel in the truncated cone 32 issued.

A fuel conveyor 20 and an air conveyor 80 (see 1a ) are in the 3 not shown, but can easily on or in the fuel line 21 or the air line 81 be provided.

The actuators are, as in 1a shown with the controller 10 connected and control according to the invention, the heating burner, that it controls the combustion flame in a preset preset ignition intervals t _Z to a preset fuel output L and this maintains for the duration of the firing interval t _B (see 5a ). The duration of the burning interval t _B is determined by the control device 10 determined as a function of the heating power to be provided by the heating burner. The 5a shows a time-burning diagram. Here are three ignition intervals t _Z shown. An ignition interval in the selected embodiment has the length of 100 seconds. The control unit thus regulates the burning power L to a preset level every 100 seconds. And keeps this higher burning power L during the firing interval t _B. The control device 10 (see 1a ) is designed such that it determines the length of the firing interval t _B for the optimum heating power required at the respective time. In the diagram of 5a determines the controller 10 that about 20% of the maximum heating power in a first firing interval t _{Z is} needed. Accordingly, at the time t = 0, it controls the burning power L at the preset level and keeps this level for Ca. 20 seconds. The remaining 80 seconds of the first firing interval t _Z become the actuators of the controller 10 regulated so that the burning power L is virtually zero. At time t = 100, the controller determines 10 that for an optimal heating power in a second ignition interval t _Z about 60% of the maximum power is needed. Accordingly, the Brennitervall t _B in this second ignition interval t _{Z is} about 60 seconds long. The same applies to a third ignition interval t _Z, which begins at time t = 200.

5b shows a time-burning power diagram of the first ignition interval t _Z from 5a the length of the firing interval t _B is, as already mentioned, 20 seconds. The start or stop phase, ie the period in which the control device 10 the firing power L is up-regulated to the preset high level or down-regulated by this as the initialization interval t _I or

Stop interval t _S called. For an efficient and low-emission combustion of the heating burner according to the invention, a constant fuel-oxygen ratio in these phases is particularly crucial. The control device 10 controls the actuators accordingly.

A detailed view of the second ignition interval t _Z out 5a can the time-burning power diagram of the 5c be removed. This precise control of the heating power allows an improved actual value setting, as shown in the 4b shown is achieved. Here the abscissa indicates the time and the ordinate the actual temperature.

LIST OF REFERENCE NUMBERS

1

combustion chamber

10

control device

20

Fuel feeding

21

fuel line

24

fuel tank

30

Cracker device

32

truncated cone

35

inlet opening

36

outlet opening

37

engine

40

preheating

42

Heat recovery

44

heating coil

50

ignition device

60

sensors

61

Air temperature sensor

62

Air flow sensor

63

Fuel temperature sensor

64

Fuel flow sensor

65

Heizwassertemperaturfühler

70

atomizer

80

Air conveyor

81

air line

t _B

burning interval

t _Z

ignition interval

t _i

initialization interval

t _s

stop interval

L

burning power

Claims (10)

Heating burner for a heating system with a control device ( 10 ), with at least one primary sensor for detecting a heating power of the heating burner and with actuators, which has an ignition device ( 50 ) for igniting fuel, an air conveyor for conveying combustion air and a fuel conveyor ( 20 ) for conveying fuel to the ignition device ( 50 ), wherein the delivery rate of the fuel delivery device ( 20 ) and / or air conveying device is substantially freely adjustable and the control device ( 10 ) adjusts the actuators in such a way that the fuel is ignited in ignition intervals (t _Z ) and burns for an adjustable firing interval (t _B ), the heat output being controlled by the control device ( 10 ) over the length of the combustion interval (t _B ) in the respective ignition interval (t _Z ) is adjustable, characterized in that the fuel is a liquid fuel and the ignition device ( 50 ) a preheating ( 40 ), which heats the fuel to ignition temperature, wherein the control device ( 10 ) adjusts the actuators such that the fuel is ignited at constant preset ignition intervals (t _Z ), and that the firing rate (L) is substantially constant during each firing interval (t _Z ) during the firing interval (t _B ) and in the remaining time the combustion flame is extinguished or reduced. Heating burner according to claim 1, characterized in that the ignition intervals (t _Z ) are less than or equal to 60 seconds. Heating burner according to one of the preceding claims, characterized in that the actuators are a motor ( 37 ) comprising a truncated cone ( 32 ) in such a rotational movement about its longitudinal axis, that via an inlet opening ( 35 ) in the truncated cone ( 32 ) introduced fuel due to the centrifugal force at an outlet opening ( 36 ) and is atomized. Heating burner according to claim 3, characterized in that the ignition device ( 50 ) a heat recovery ( 42 ), which is made of thermally conductive material and emits the heat generated during combustion of the fuel to the inflowing fuel. Heating burner according to claim 4, characterized in that the heat recovery ( 42 ) at least in sections inside the truncated cone ( 32 ) the outlet opening ( 36 ) is superior. Heating burner according to one of the preceding claims, characterized in that the preheating ( 40 ) a heating coil ( 44 ) comprising the truncated cone ( 32 ) surrounds. Heating burner according to one of the preceding claims, characterized in that the control device ( 10 ) is designed such that it the fuel conveyor ( 20 ) and the air conveyor ( 80 ) controls such that during the firing interval (t _B ), preferably in an initialization interval (t _I ) and a stop interval (t _S ), a substantially constant air fuel ratio at the ignition device ( 50 ) is present. Heating burner according to claim 7, characterized by an air flow sensor ( 62 ) for determining the delivery rate of the air conveyor device ( 80 ). Heating burner according to one of the preceding claims, characterized in that the control device ( 10 ) the fuel delivery device ( 20 ) and the air conveyor ( 90 ), such that outside of the firing interval (t _B ) a pilot flame is present. Heating burner according to claim 9, characterized in that the control device ( 10 ) is designed such that it supplies the fuel delivery device ( 20 ) outside the firing interval (t _B ) so that less than 1%, preferably less than 1 per thousand, of the maximum delivery rate of the fuel delivery device ( 20 ).

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