WO2016091433A1

WO2016091433A1 - Fuel mixture supply device

Info

Publication number: WO2016091433A1
Application number: PCT/EP2015/073517
Authority: WO
Inventors: Robbert DE BRUIN; Remko Voordendag; Gordy Koellmann
Original assignee: Robert Bosch Gmbh
Priority date: 2014-12-09
Filing date: 2015-10-12
Publication date: 2016-06-16
Also published as: DE102014225226A1

Abstract

The invention relates to a fuel mixture supply device, which is provided to adjust a fuel-air ratio of a fuel mixture (18), comprising at least one automatic valve (12) which is provided to adjust a fuel volume flow (14) as a function of at least one combustion characteristic value. It is proposed that the fuel mixture supply device comprises a flow unit (16) which is provided to change the fuel volume flow (14) by the automatic valve (12) as a function of a combustion air volume flow (20).

Description

description

Brennstoffgemischzuführvorrichtung

State of the art

The invention relates to a Brennstoffgemischzuführvorrichtung according to the preamble of patent claim 1.

There is already known a Brennstoffgemischzuführvorrichtung, which is intended to adjust a fuel-air ratio of a fuel mixture. This has an automatic valve which is provided to set a fuel volume flow in dependence on a combustion characteristic value. The known Brennstoffgemischzuführvorrichtung has a non-negligible dead time between a change in the fuel flow and a measurable effect on the Verbrennungskennwert.

Disclosure of the invention

The invention is based on a Brennstoffgemischzuführvorrichtung, which is intended to adjust a fuel-air ratio of a fuel mixture, with at least one automatic valve, which is intended to a

Adjust fuel flow as a function of at least one combustion parameter.

It is proposed that the Brennstoffgemischzuführvorrichtung a

Flow unit, which is intended to change the fuel flow rate through the automatic valve in response to a combustion air flow rate. Under a "Brennstoffgemischzuführvorrichtung" should in this connection In particular, a device for use within a burner system, in particular a gas burner system, can be understood. In particular, the fuel mixture supply device within a burner system is connected upstream of a burner, in particular a gas burner, in particular in terms of flow. In particular, the Brennstoffgemischzuführvorrichtung one or more

Hollow pipes, in particular pipes, comprise, which are provided in particular for transporting a fuel, preferably a gaseous fuel, and / or a combustion air and / or a fuel mixture in the direction of the burner. In particular, the term "provided" should be understood to mean specially programmed, designed and / or equipped.Assuming that an object is intended for a specific function should in particular mean that the object fulfills this specific function in at least one application and / or operating state A "fuel" in this context is preferably a hydrocarbon-containing gas or gas mixture, preferably a natural gas or a natural gas mixture, in particular a natural gas, a

Liquefied gas or a biogas which comprises at least one alkane, in particular methane, ethane, propane and / or butane. In this context, a "fuel mixture" is to be understood as meaning, in particular, an ignitable mixture of a fuel and a combustion air which is intended to be supplied to a burner for carrying out a combustion process Fuel mixture at least partially and preferably completely within the Brennstoffgemischzuführvorrichtung.A "fuel-air ratio" is to be understood in this context, in particular a ratio of fuel to combustion air within the fuel mixture.

An "automatic valve" is to be understood in this context, in particular a control valve, which is intended to at least one

Operating state, in particular a volume flow of a flowing into the automatic valve and / or the automatic valve by flowing, in particular gaseous, fuel at least semi-automatically or preferably fully automatically adjust and / or to regulate. In particular, the at least one automatic valve has at least one throttle element whose position and / or orientation and / or shaping can be actively changed, in particular as a function of at least one controlled variable. In particular, by changing the

Position and / or the orientation and / or the shaping of the at least one Throttle element at least one flow path, along which the at least one automatic valve can be flowed through by a fuel, expandable and / or narrowed. Under that, that at least one automatic valve "a

Fuel volume flow setting as a function of at least one combustion characteristic is to be understood in this context, in particular, that the at least one flow path along which the at least one automatic valve is flowed through by a fuel is expanded or narrowed according to a currently present combustion characteristic. For this purpose, the at least one automatic valve has, in particular, a control and / or regulating unit and / or is connected to a control and / or regulating unit, which is provided to evaluate the at least one combustion characteristic and into one of the position and / or orientation and / or shaping the at least one throttle element of the at least one automatic valve in accordance with the combustion characteristic value changing control and / or control signal to transfer.

In this context, a "combustion characteristic value" should be understood to mean, in particular, a parameter which contains at least information about a quality of a combustion process, in particular about a quality of a combustion process within a burner, preferably within a gas burner

Contain information which reflects a composition of a fuel gas mixture supplied to the burner, preferably a fuel-air ratio of the fuel gas mixture. A detection of the at least one combustion characteristic value can in particular be effected by means of at least one sensor in an exhaust gas stream of the combustion process and / or preferably by means of at least one sensor in one

Combustion flame of the combustion process take place. The at least one combustion characteristic value can be embodied in particular as an oxygen content and / or a carbon dioxide content and / or a carbon monoxide content of a combustion exhaust gas and / or preferably as an ionization flow detected in a burner flame. In particular, the at least one combustion characteristic value can be detected by means of an oxygen sensor and / or a carbon dioxide sensor and / or a carbon monoxide sensor in an exhaust gas stream of the combustion process and / or preferably by means of an ionization electrode within a combustion flame of the combustion process. The at least one combustion characteristic value is in particular different from a combustion air volume flow. A detection of the at least one combustion characteristic may in particular re in, in particular fixed, time intervals and / or preferably carried out continuously.

In this context, a "flow unit" should be understood as meaning in particular a unit downstream of the automatic valve which has at least one mixing element which is provided to mix a fuel volume flow leaving the automatic valve with a combustion air volume flow with the at least one mixing element fluidly connected fuel supply line, at least one fluidly connected to the at least one mixing element

Combustion air supply line and at least one fluidically connected to the at least one mixing element fuel mixture derivative. The fact that the flow unit "changes the fuel volume flow through the automatic valve as a function of a combustion air volume flow" is to be understood in this context as meaning that the flow unit changes when a combustion air volume flow through the flow unit, in particular through the at least one mixing element of the flow unit, By such a configuration, a generic

Brennstoffgemischzuführvorrichtung be provided with improved operating characteristics. In particular, a fuel volume flow can advantageously be set both as a function of a combustion characteristic value and also changed as a function of a combustion air volume flow. Thus, advantageously, a fuel-air ratio of a fuel mixture can be advantageously adjusted simply and / or reliably both with a changing fuel composition and with a changing combustion-air volume flow.

It is also proposed that the flow unit is provided to change the fuel flow through the automatic valve, regardless of a setting of the automatic valve. Under that "the flow unit the

Fuel volume flow through the automatic valve regardless of a setting of the automatic valve changes "is to be understood in this context in particular that caused by the flow unit change in the fuel volume flow through the automatic valve in particular at an unchanged valve position of the automatic valve takes place. unit caused change in the fuel flow through the automatic valve regardless of the at least one combustion characteristic. As a result, a change by means of the flow unit can advantageously be decoupled from a change in the fuel volume flow by means of the automatic valve. Furthermore, a change in the fuel volume flow by means of the flow unit can take place independently of the at least one combustion characteristic value, as a result of which a dead-time-loaded feedback path can be advantageously avoided.

Furthermore, it is proposed that the flow unit is provided to change the fuel volume flow through the automatic valve at least substantially in proportion to a change in the combustion air volume flow. By "at least essentially" is to be understood in this context in particular that a deviation from a predetermined value in particular less than 20%, preferably less than 10% and more preferably less than 5% of the predetermined value deviates - ratio of one

Fuel mixture are kept at least largely constant at a change in the combustion air flow rate.

In a preferred embodiment of the invention it is proposed that the flow unit is provided to the fuel flow through the

Change automatic valve by means of a pressure change at an outlet opening of the at least one automatic valve. In particular, the flow unit is provided to lower a pressure at an outlet opening of the at least one automatic valve with an increase in the combustion air volume flow and / or the pressure at the outlet opening of the at least automatic valve with a decrease in the

Increase combustion air volume flow. In particular, a change in the pressure at the outlet opening of the at least one automatic valve takes place in such a way that a change in the volume of fuel flow through the automatic valve proportional to a change in the combustion air volume flow results. This can be advantageously simple way a change in the fuel flow through the

Automatic valve can be achieved.

Advantageously, the flow unit has at least one Venturi pump and / or at least one reduction, which is intended to provide a pressure at the

Outlet opening of the automatic valve depending on the

Change combustion air volume flow. Under a "Venturi pump" in this Connection in particular a pump can be understood, which consists of at least one particular smooth-walled pipe having a constriction of its cross section. The narrowing of the cross section may be formed for example by two oppositely directed cones, which are united at the location of their smallest diameter. In particular, the venturi pump has at least one take-off line which opens into the pipeline at least substantially at the point of the constriction and runs at the confluence at least essentially to a main through-flow direction of the pipeline. In particular, the take-off line fluidly connects an outlet opening of the at least one automatic valve with the at least one venturi pump. The at least one

Venturi pump at least partially forms the mixing element of the flow unit. Along the main flow direction of the pipeline flows in particular the combustion air volume flow. In particular, a supply of the fuel volume flow takes place via the at least one take-off line. In particular, a mixing of the fuel volume flow with the combustion air volume flow takes place within the Venturi pump. In this context, a "reduction" should be understood to mean, in particular, an element which is intended to narrow a cross-section of the combustion air supply line in at least one point in a flow direction, at least one take-off line, which fluidly connects an outlet opening of the at least one automatic valve with the combustion air supply line The use of a Venturi pump and / or a reduction can in a simple and / or reliable manner change a pressure at an outlet opening of the at least one automatic valve, in particular as a function of the combustion air volume flow , be achieved.

It is further proposed that the flow unit is provided to the fuel flow through the automatic valve at an occurrence of

Change in the combustion air flow rate at least substantially without delay. In this context, "at least essentially time-delay-free" should be understood to mean that a dead time between a change in the combustion air volume flow and a change in the fuel volume flow through the automatic valve is a maximum of 5 seconds, preferably a maximum of 3 seconds, advantageously a maximum of 1 second and especially is advantageously not more than 0.5 seconds. special sudden change in the combustion air flow rate can be reacted, whereby a change in the fuel-air ratio can be at least largely prevented.

Advantageously, the automatic valve is designed as an electronic control valve. In this context, an "electronic control valve" should be understood to mean, in particular, a valve whose valve position can be changed, in particular by means of electrical signals.

Further, a method for adjusting a fuel-air ratio with a Brennstoffgemischzuführvorrichtung invention, proposed, wherein a fuel flow is adjusted by means of at least one automatic valve in response to at least one combustion characteristic value and by the

Automatic valve guided fuel flow as a function of a

Combustion air volume flow is changed. As a result, a fuel-air ratio of a fuel mixture can advantageously be adjusted simply and / or quickly and / or reliably. In particular, fluctuations in the fuel / air ratio can be advantageously reduced, in particular due to fluctuations in a fuel composition and / or a combustion air volume flow.

The fuel mixture supply device according to the invention should not be limited to the application and embodiment described above. In particular, in order to fulfill a mode of operation described herein, the fuel mixture supply device according to the invention may have a number deviating from a number of individual elements, components and units mentioned herein.

drawing

Further advantages emerge from the following description of the drawing. In the drawing, an embodiment of the invention is shown. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations. It shows: a burner system with a Brennstoffgemischzuführvorrichtung wel che having an automatic valve and a flow unit.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT FIG. 1 shows a burner system 28 embodied as a gas burner system. The burner system 28 comprises a burner 30 and a fuel mixture supply device 10 upstream of the burner 30. A gaseous fuel 38, for example a natural gas, is fed to the burner system 28 via a fuel feed line 34. A combustion air 40 is supplied to the burner system 28 via a combustion air supply line 36. The fuel 38 and the combustion air 40 are mixed to form an ignitable fuel mixture 18 and fed to the burner 30. The fuel mixture 18 is fed by means of an electric blower 42 connected upstream of the burner 30. The fuel mixture feed device 10 is provided to set a fuel / air ratio of the fuel mixture 18 supplied to the burner 30. The during the combustion process in the

Burner 30 resulting combustion gases 48 are discharged via an exhaust pipe 50.

The fuel mixture supply device 10 initially has an automatic valve 12 for adjusting the fuel-air ratio of the fuel mixture 18. the

Automatic valve 12 is here a shut-off valve 54 upstream. The automatic valve 12 is disposed in the fuel supply line 34. The automatic valve 12 is preferably designed as an electronic control valve 26. The automatic valve 12 is provided to set a fuel volume flow 14 as a function of a combustion characteristic. The combustion characteristic value is formed here by way of example as an ionization stream, which is detected by means of an ionization electrode 44 in a combustion flame 46 of the burner 30. Alternatively or additionally, it would also be conceivable to detect an oxygen content and / or a carbon dioxide content of a combustion exhaust gas 48 and to use it as a combustion characteristic value. The combustion characteristic value contains, in particular, information which makes it possible to draw conclusions about a composition of the fuel mixture 18. In particular, the combustion characteristic value makes it possible to draw conclusions about a fuel-air ratio of the fuel mixture 18. Based on the combustion characteristic value, a signal for activating the automatic valve 12 is generated and the fuel volume flow 14 is set by the automatic valve 12 as a function of the combustion characteristic value. For example, it is possible to react so reliably to a changed composition of the fuel 38 used. However, the disadvantage of setting the fuel volume flow 14 to a non-negligible dead time. This dead time arises between the detection of a change in the combustion characteristic and an effect of a resulting change in the fuel flow rate 14. Due to the dead time can by means of the automatic valve

12 are insufficiently responsive to sudden changes in the combustion air volume flow 20 resulting in an undesirable change in the fuel-air ratio of the fuel mixture 18. To compensate for this disadvantage, the Brennstoffgemischzuführvorrichtung 10 further comprises a flow unit 16. The flow unit 16 is provided to change the fuel volume flow 14 through the automatic valve 12 as a function of the combustion air volume flow 20. For this purpose, the flow unit 16 has a venturi pump 24. The venturi pump 24 is arranged in the combustion air supply line 36. Via a take-off line 52, the venturi pump 24 is connected to an outlet opening 22 of the automatic valve 12. Within the venturi pump 24, the fuel 38 is mixed with the combustion air 40 to the fuel mixture 18. The combustion air volume flow 20 is through the

Venturi pump 24 passed. A change in the combustion air volume flow 20 causes a dependent on the change in the combustion air volume flow 20

Pressure change at the outlet opening 22 of the automatic valve 12. The flow unit 16 is designed such that a change in the combustion air volume flow 20 in a proportional thereto change in the fuel flow rate 14 results. The change of the fuel volume flow 14 takes place independently of a setting of the automatic valve 12. In particular, the change of the fuel volume flow 14 by means of the flow unit 16 does not require activation of the automatic valve 12 and / or detection and / or evaluation of the combustion characteristic value. However, this requires that by means of the flow unit 16, for example, no adjustment of the fuel flow 14 to a modified fuel composition is possible. However, this disadvantage is compensated by the use of the automatic valve 12. The structure of the flow unit 16 further enables When there is a change in the combustion air volume flow 20, the fuel volume flow 14 can be adapted to the changed combustion air volume flow 20 without delay. This makes it possible for a fuel-air mixture of the fuel mixture 18 to be kept constant even in the event of a sudden change in the combustion air volume flow 20. Such a sudden change in the combustion air volume flow 20 can be caused, for example, by a suction induced by a wind 56 on the exhaust pipe 50 and / or by a wind attack on the combustion air supply line 36 and / or by a, for example by a burner control 58 initiated speed change of the blower 42 ,

Claims

claims

1 . A fuel mixture supply device, which is intended to set a fuel-air ratio of a fuel mixture (18), with at least one automatic valve (12), which is arranged to set a fuel volume flow (14) in dependence on at least one combustion characteristic, characterized by a flow unit (16), which is intended to change the fuel volume flow (14) through the automatic valve (12) in response to a combustion air volume flow (20).

2. Brennstoffgemischzuführvorrichtung according to claim 1, characterized in that the fuel mixture (18) is gaseous.

3. Brennstoffgemischzuführvorrichtung according to claim 1 or 2, characterized in that the flow unit (16) is provided to change the fuel flow (14) through the at least one automatic valve (12) regardless of a setting of the automatic valve (12).

4. Brennstoffgemischzuführvorrichtung according to any one of the preceding claims, characterized in that the flow unit (16) is provided, the fuel volume flow (14) through the at least one automatic valve (12) at least substantially proportional to a change in the combustion air volume flow (20) to change.

5. Brennstoffgemischzuführvorrichtung according to any one of the preceding claims, characterized in that the flow unit (16) is provided, the fuel volume flow (14) through the at least one automatic valve (12) by means of a pressure change at an outlet opening (22) of the at least one automatic valve (12 ) to change. Brennstoffgemischzuführvorrichtung according to any one of the preceding claims, characterized in that the flow unit (16) has at least one Venturi pump (24) and / or at least one reduction, which is intended to a pressure at the outlet opening (22) of the at least one automatic valve (12) depending on the combustion air volume flow (20) to change.

Brennstoffgemischzuführvorrichtung according to any one of the preceding claims, characterized in that the flow unit (16) is provided to change the fuel flow (14) through the at least one automatic valve (12) at an occurrence of a change in the combustion air volume flow (20) at least substantially without time delay.

Brennstoffgemischzuführvorrichtung according to any one of the preceding claims, characterized in that the at least one automatic valve (12) as an electronic control valve (26) is formed.

Method for adjusting a fuel-air ratio with a

Brennstoffgemischzuführvorrichtung (10), in particular according to one of claims 1 to 8, wherein a fuel volume flow (14) is adjusted by means of at least one automatic valve (12) in dependence on at least one combustion characteristic, characterized in that by the at least one automatic valve (12) led Fuel volume flow (14) in response to a combustion air flow rate (20) is changed.

10. Burner system, in particular gas burner system, with a

Brennstoffgemischzuführvorrichtung (10), in particular according to one of claims 1 to 9.