CN1291700A

CN1291700A - Method of adjusting burner characteristic curve

Info

Publication number: CN1291700A
Application number: CN00127007A
Authority: CN
Inventors: 汉斯·林克; 哈拉尔德·豪特
Original assignee: Siemens Building Technologies AG
Current assignee: Siemens Building Technologies AG
Priority date: 1999-10-06
Filing date: 2000-09-13
Publication date: 2001-04-18
Also published as: EP1091174A1; KR20010050868A; JP2001141234A

Abstract

A method of adjusting a burner characteristic curve. Starting from the output values having at least a relative air value and a fuel value, an output value, the flow rates of air and fuel, and possible auxiliary drive device are changed in a first direction until a measured exhaust gas value changes to a next power value. Continuously, the next air value and fuel value are set at the next output value so that a prescribed exhaust gas value may be obtained. Due to the changing of the the output value, flow rates of air and fuel, and possible auxiliary drive device, a next air value and fuel value are determined by the defined exhaust gas parameters being set once more. Also continuously, the flow rates of air and fuel are changed again in the direction which is decided by the results of the exhaust gas measurement and the preceding exhaust gas measurement.

Description

Method for adjusting characteristic curve of combustor

The invention relates to a method for adjusting a characteristic curve of a burner or an ignition device.

A number of such methods for adjusting the characteristic curve of a burner are known, in which for each power or output value of the burner a different air, fuel or other adjusting parameter or value and/or an auxiliary value of an auxiliary drive of the ignition device is stored in a computer, so that, when a given output command is issued, the computer adjusts the respective control elements, such as the pump, the unit and the fan, so that the burner can reach the respective output phase. In this case, in particular in modern ignition systems, care must be taken to ensure that for each output value, an exhaust gas value which is as optimal as possible, i.e. as predetermined as possible, is observed.

Since, in order to obtain a properly determined value of the exhaust gas, at least one air value and one fuel value must be fixed for each individual burner output value, methods are known for adapting such a burner characteristic curve, i.e. for each different output phase of the burner, a corresponding air and fuel value is fixed separately. In which the air or fuel supply is continuously or repeatedly changed until an optimum exhaust gas is given for the respective output phase. In this case, the output is "readjusted" according to the supply amount of air or fuel. It is known, for example, from DE 3039994C 2 or EP 0209771 a1 that, when the burner is put into operation, the optimum air supply is detected in a point-wise manner by selecting individual fuel values during the charging process concerned, using measurements of the respective exhaust gas values, and then stored in a computer.

Furthermore, it is known from DE 19749506C 1 to wait for the fuel flow to stabilize during operation of the ignition device and then to optimize the burner characteristic curve by changing the air supply quantity, wherein the minimum air supply quantity required is based on the occurrence of exhaust gases, for example flue gases.

However, because the optimum gas supply is non-linearly related to the corresponding fuel flow, the above method can only establish a characteristic curve of the burner with respect to a specific fuel flow. Depending on the burner design, the nature of the fuel and the design layout of the heating system or ignition device concerned, there will be different air and fuel ratios at different output stages or output values of the burner.

A disadvantage of the known method of adjusting the respective characteristic curve is that the process of continuously fixing the individual points means that adjusting such a characteristic curve is extremely tedious and expensive, whereas a pre-adjustment of such a characteristic curve in a factory generally results in non-optimal combustion conditions or emission gas values in the particular use of the ignition device. In this case, the operator or installer of the heating system is also required to optimize the characteristic curve of the burner continuously, one after the other, i.e. in a point-by-point manner.

The object of the invention is therefore to improve the known methods for adjusting the characteristic curve of a burner, so that a corresponding characteristic curve can be established quickly and inexpensively.

The invention provides a method for adjusting a characteristic curve of a burner, wherein a defined exhaust gas value is set by changing an air value, a fuel value and possibly an auxiliary value depending on an output value of the burner. Wherein the air/fuel value represents a measure relative to the air/fuel flow in the combustor.

Wherein:

the output of the burner is changed starting from a first output value, in this case an air value, a fuel value and possibly auxiliary values,

as a result of the varying output, air flow and/or fuel flow and/or auxiliary drive in the respective first direction, until the exhaust gas value changes to the next output value,

at said next output value, determining at least one next air value and/or at least one next fuel value by setting again a defined exhaust gas value,

when the output is changed, the air flow and/or fuel flow and/or auxiliary drive is changed from the next output value in the respective first direction, which takes into account the above result and at least one further exhaust gas measurement.

In a preferred embodiment, the method of adjusting the burner air or fuel characteristic or other control element characteristic according to the invention is divided into the following steps:

first, the output of the burner is changed starting from a first output value with a first air value, a first fuel value and possibly a first auxiliary value, as a result of which the output, the air flow and/or the fuel flow and/or the auxiliary drive vary in respective first directions which correspond to the direction of displacement of the entire array (all the adjusting elements) along a substantially defined characteristic curve (point of the curve) until the exhaust gas value changes to the next output value. In the above process, only the output adjustment is used as an independent parameter, while the individual air/fuel and/or auxiliary values are automatically changed based on the first direction. Thus, the installer does not have to repeatedly change the individual values in succession, but only the corresponding output values of the burner.

Then, at the next output value, the corresponding air flow rate or the corresponding fuel flow rate or the value of the other auxiliary drive is changed by setting again the defined exhaust gas value, i.e. the corresponding air and fuel flow rates are changed at said output value, so that the next air value and the next fuel value are set and the defined exhaust gas value is generated again.

Then, once the output of the burner is readjusted, the air flow, the fuel flow and possibly other auxiliary drive values are no longer varied in the first direction but in a corresponding other direction, i.e. the next direction, which takes into account the above-mentioned result and at least one further exhaust gas measurement, for example the previous one. These three steps are then repeated in succession until a final output value, for example the maximum output value, i.e. the nominal output of the burner, is reached.

For example, the ignition position of the burner is used as the first point on the curve, as long as other values are known for, for example, low loads. The fuel value defined by the ignition position is temporarily used as an output value. This point may also be used initially as a low load point. However, as the first output value, it is recommended that the minimum load (low load) of the combustor may also be used, if this value is known. In this case, the air flow, the fuel flow and possibly other auxiliary drives vary linearly at the beginning of the adjustment process in the direction of the maximum value of the maximum output of the burner, when the output increases accordingly. Thus, in the respective output, air and fuel diagrams, as the output increases, the air and fuel flow rates each vary linearly along a line beginning at the first, e.g., minimum air and fuel value or value beginning at the ignition position, respectively, and extending to the respective maximum air or fuel value (90 of the opening angle of the control element; 100 of the output). Thus, starting from the first point on the curve, the output value increases (air and fuel flow increases) until the exhaust gas value changes. At this position (middle point), an air value, a fuel value or an auxiliary value is set and stored.

Once the next air and fuel values are determined, the air and fuel flow rates change in the other direction as soon as the output changes. This direction is produced, for example, by the extension of the straight line through the respective last defined air and fuel values. In this case, the line generally no longer passes through the previously assumed final point, i.e. the bisecting point of maximum output at maximum fuel and air flow, but rather another line.

However, when the next air value and/or the next fuel value or the next auxiliary value is determined, the air flow and/or the fuel flow or the corresponding auxiliary drive also changes in the direction of the maximum or minimum air and fuel flow or the maximum or minimum adjustment value relative to the auxiliary drive when pointing to the maximum or minimum burner output, respectively, depending on whether the adjustment, i.e. the output change, is effective in the direction of the output value becoming larger or smaller. In this case, the respective last determined values are used to establish a characteristic curve between these values and the values already established before.

In the described method for adjusting the air and fuel characteristic curves, additional characteristic curves can be created equally well. For example, it may be an auxiliary drive, a back-up pump or other adjustment element for optimizing burner tuning. All parameters, i.e. adjustment options, can be determined simultaneously when starting each output value, i.e. each new output value. The following principles may be used to establish a suitable output value at which time the air, fuel or other value is readjusted to also establish a new direction for the shape of the characteristic curve at a later time.

Allowable different combustion value intervals can be used as defined exhaust gas values such that when above or below one or more different combustion value interval limits, a process of determining a next fuel value or a next air value or other value is initiated.

An air, fuel or other characteristic is then given by successively combining the segments between the previously established air and fuel values. The characteristic curve is adjusted to optimize the burner before the burner is started or during maintenance. Even if a part of the burner or the burner device itself is replaced, the corresponding characteristic curve can be quickly and easily reconstructed by the method according to the invention without intervention operations in the plant which have to be carried out in connection with the respective control system or regulating device.

After a first adjustment of the characteristic curve of the burner or of the individual fuel or air characteristic curves, the admissible intervals of different combustion values are reduced or decreased, thereby placing more stringent requirements on the shape of the characteristic curve. Since the "optimization" of the characteristic curve is updated, i.e. the individual output ranges are passed through the burner again, above or below the now decreasing interval, an updated "optimization point", i.e. the burner output value, is given by the exhaust gas value again lying within the already decreasing interval, at which time the individual air, fuel and other values are optimized, i.e. readjusted.

In the above-described method, the burner can be optimized with the required precision by combining the individual straight segments in succession.

To this end, according to a further preferred embodiment of the invention, the output values that have been set can be reached exclusively and precisely along the characteristic curve that has been set, by setting again defined exhaust gas values, in order to determine updated air values and/or fuel values or auxiliary values. The new air and/or fuel values or auxiliary values are used to adjust or reestablish the characteristic curve.

According to a further preferred embodiment of the invention, the output value given can be approached exclusively and precisely along the characteristic curve already set and, if it turns out that the originally defined output value does not match, a new output value can be determined on the basis of the air value and/or the fuel value or the auxiliary value or by means of an output measurement method and used for adjusting or reconstructing the characteristic curve.

It is also possible to combine the above-described methods, in which a given output value is approached exclusively and precisely along an already set characteristic curve, new air and/or fuel values or auxiliary values are determined by resetting defined exhaust gas values, these new air and/or fuel values or auxiliary values being used to determine the new output value at the output value or by means of output measurement methods, and the characteristic curve is adjusted or reestablished.

The respective drives of the air, fuel or auxiliary control elements are varied with a predetermined ramp speed (rampspeed). In this respect, the ramp speed is the maximum speed at which the control element is changed, preferably between 30 and 120 seconds for a 90 ° displacement. Depending on the individual "gradient" of the individual characteristic curve or of the section of the characteristic curve between two values of air, fuel or auxiliary drive, the control element is varied with the individual ramp speed, so that the flow rate varies with the characteristic curve, i.e. with the steepness of the characteristic curve. When the output changes by, for example, 15%, the air characteristic curve portion is between 30 ° and 40 °, the fuel characteristic curve portion is between 25 ° and 30 °, the ramp speed is set to 30 s/90 °, the air-moving device is moved at full ramp speed, and the fuel drive is moved at half ramp speed. The time required for this was 3.33 s. In this way, the entire array is moved along the characteristic curve during output adjustment without excessive drift from the characteristic curve, worsening combustion and resulting higher polluting emissions.

Furthermore, a single established "support point", i.e. the corresponding air or fuel value for a single output value, can be combined with a second, third or higher order function, when the corresponding function has to be determined with reference to three, four or more points on the corresponding characteristic curve. Certain requirements with regard to the accuracy of the individual characteristic curves can be met in this respect according to the respective interpolation algorithm.

Preferred embodiments of the present invention are described in more detail below with reference to the accompanying drawings. Wherein,

FIG. 1 is a schematic diagram of an ignition apparatus;

FIG. 2 is a first step in adjusting 3 characteristic curves;

FIG. 3 is a second step of adjusting the 3 characteristic curves;

FIG. 4 is a final representation of a combustor characteristic curve;

fig. 5 is another adjustment of the characteristic curve.

Fig. 1 schematically shows a burner 1 to which fuel 3 and air 2 are supplied. It is assumed that the burner regulator 7 acting on the respective fuel control element 4 and air control element 5 is used to regulate the air supply quantity and the fuel supply quantity, respectively. To adjust the air supply and fuel supply, the burner regulator 7 receives a signal from the exhaust gas probe 6. The exhaust gas probe 6 issues a plurality of exhaust gas or combustion values for the exhaust gas 8 to the burner regulator 7. For each output phase or exhaust gas value P1 … n of the burner, the method according to the invention is used to adjust the characteristic curve in order to obtain the corresponding air value Ai and fuel value Fi, which are then used to optimally adjust the combustion process in the burner regulator 7.

A preferred procedure for carrying out the method according to the invention is described below with reference to fig. 2 to 4.

For the respective

characteristic curves

2, 3 and H of the burner, after setting the appropriate specific positions of the

control elements

4 and 5 or also the position of the auxiliary drive, an adjustment of the ignition position Z of the individual characteristic curves is first carried out. As shown in fig. 2, there are 3 different positions for the fuel, air and auxiliary drive means. Wherein the auxiliary drive is optional.

After the ignition position Z is adjusted, the first output value P is acquired after the burner 1 is set to the operating state₁. This value represents a low load position if this position is known. Otherwise, the first fuel value is used as the output value using the ignition position. This gives the air value A₁Fuel value F₁And an auxiliary drive value (hereinafter referred to as auxiliary value) H₁. If the first output value is not yet explicitly entered as a low-load position in advance, the control unit, i.e. the burner regulator 7, also initially assumes the position Z entered for the ignition, the first output position, i.e. the first output value P₁。

Then, the actual adjustment process of the burner profile is started. The adjustment is performed on the basis of the fuel characteristic curve 3, the air characteristic curve 2 and the auxiliary characteristic curve H. In a preferred embodiment of the invention, the operator incrementally adjusts the output value to adjust the characteristic curve of the burner. The starting point used in this case is the first output value P mentioned above₁Such as a low load point. From this point on, the burner 1 is adjusted in the direction to a higher output, either by manual operation mode or automatic operation mode; for the first direction, the process includes varying individual fuel or air, etc. along a straight lineThe value is obtained. These straight lines pass through the first mentioned point and the maximum point at maximum output and the maximum displacement of the control elements 4, 5 (90 ° as shown in fig. 2); thus, the fuel, air and auxiliary values move along interpolated and/or extrapolated straight lines. The auxiliary point H then starts as a start at the first air value a₁Fuel value F₁And an auxiliary value H₁As an orientation aid. In fig. 2, the first direction is identified as R1 for the auxiliary drive curve H.

FIG. 3 shows the second output value P₂The combustion value, i.e. the previously defined exhaust gas value, is no longer reached, or the combustion value changes in such a way that it is no longer within a fixed predetermined interval. At the output value P₂New air, fuel and auxiliary values are established and defined exhaust gas values are again derived. Readjusts the corresponding air value A₂Fuel value F₂And an auxiliary value H₂The result is then that a new direction R is formed for each of the air characteristic curve 3, the fuel characteristic curve 2 and the auxiliary characteristic curve H₂. The new direction R₂By connecting the respective two last-defined points A₁、A₂And F₁、F₂Or also H₁、H₂Obtained by extrapolation of the corresponding straight lines of (a).

According to the method described above, the installation personnel of the heating system, the operating personnel of the burner or also the maintenance are carried out until the burner reaches its maximum output, i.e. the nominal output P_maxPoint (2) of (c).

As shown in FIG. 4, by using R is shown₁、R₂And R₄The directions indicated respectively are characteristic curves obtained by successively combining single straight line portions.

When the individual characteristic curves of the burner have been established according to the invention and the method shown in FIG. 4, it is possible to use the characteristic curves on an empirical basis, for example at the air value A₅Initially, it is moved back along a defined characteristic curve to further fine tune the burner. This "top-down" movement allows for phase-dependentThe fine adjustment is carried out in response to the provision of a smaller interval limit for the combustion value. In this case, however, it is also possible to specifically and precisely reach a single output value lying between (for example midway) the previously defined values in order to further optimize the characteristic curve in the manner described above.

The individual support points of the characteristic curve are suitably defined by the corresponding output information. The output information is the output value and the position information relating to the control drive used. The control drive used is, for example, a fuel drive 4 or an air drive 5.

Fig. 5 shows an adjustment of another characteristic curve. Wherein the next air value A is determined_i+1And/or the next fuel value F_i+1Or the next auxiliary value H_i+1After that, the air flow and/or fuel flow or the corresponding auxiliary drive is respectively along the combustor at the maximum or minimum output P_max、P₀In a direction R with respect to the maximum or minimum air and fuel flow of the auxiliary drive_x、R₀And (4) changing. In this case, for example, the third air value A₃For adjusting the second air value A₂And a third air value A₃With the air flow along a third air value a in the direction of higher output₃And the auxiliary value X.

Claims

1. A method of adjusting a characteristic curve of a burner, wherein a defined value of the exhaust gas is set in dependence on an output value (P) of the burner_1……n) To change the air value (A)_i) Fuel value (F)_i) And possibly auxiliary values (H)_i) Where the air/fuel value represents a measurement related to the air/fuel flow in the combustor,

wherein:

from the first output value (P)₁) The output (P) of the burner is changed, when the air value (A) is available₁) Fuel value (F)₁) And canAuxiliary value of energy (H)₁)，

Due to the varying output (P), the air flow and/or the fuel flow and/or the auxiliary drive are/is in the respective first direction (R)_i) Is changed until the value of the exhaust gas becomes the next output value (P)_i+1)，

At said next output value (P)_i+1) Determining at least one next air value (A) by resetting the defined exhaust gas value_i+1) And/or at least one next fuel value (F)_i+1)，

When the output (P) changes, the next output value (P) is used_i+1) Initially, the air flow and/or fuel flow and/or the auxiliary drive are varied in the respective next direction, which takes into account the above result and at least one further measured value of the exhaust gas.

2. Method according to claim 1, characterized in that the ignition position or the minimum load (P) of the burner_min) Used as the first output value (P)₁) When the output (P) increases, the air flow, the fuel flow and the possible auxiliary drives follow the maximum output (P) at the burner_max) And a first direction of maximum air and fuel flow or maximum control value of the maximum auxiliary drive.

3. A method according to claim 1 or 2, characterized in that the next air value (a) is determined on the basis of a change in the output (P)_i+1) And/or the next fuel value (F)_i+1) Or the next auxiliary value (H)_i+1) Then, the air flow and/or fuel flow or the corresponding auxiliary drive are respectively along a second direction (R)₂) Change of direction by passing through two last defined air values (A)_i；A_i+1) Or fuel value (F)_I；F_i+1) Or an auxiliary value (H)_i；H_i+1) Is generated by interpolation or extrapolation of the straight lines of (a).

4. The method of claim 1 or 2Characterised in that, on the basis of the variation of the output (P), the next air value (A) is determined_i+1) And/or the next fuel value (F)_i+1) Or the next auxiliary value (H)_i+1) Air flow and/or fuel flow or corresponding auxiliary drives along the path of maximum or minimum burner output (P), respectively_max，P₀) Direction of maximum or minimum air or fuel flow or maximum or minimum control value of auxiliary drive (R)_x，R₀) And (4) changing.

5. Method according to any of the preceding claims, characterized in that the admissible interval of different combustion values is used as a defined exhaust gas value, and that the determination of the next fuel value (F) is initiated when above or below one or more different combustion value interval limits_i+1) Or the next air value (A)_i+1) Or an auxiliary value (H)_i+1) The process of (1).

6. A method according to any one of the preceding claims, characterized in that the characteristic curve of the burner is established by continuously combining the individual segments resulting from the straight lines defined between the air/fuel values or the auxiliary values.

7. Method according to any of the preceding claims, characterized in that the given output value (P) is approached exclusively along the characteristic curve that has been set_i) And determining a new air value (A) by resetting the defined exhaust gas value_i ^*) And/or fuel value (F)_i ^*) Or an auxiliary value (H)_i ^*) Said new air value (A)_i ^*) And/or fuel value (F)_i ^*) Or an auxiliary value (H)_i ^*) For adjusting or resetting the characteristic curve.

8. Method according to any of claims 1 to 6, characterized in that the given output value (P) is approached exclusively along the characteristic curve that has been set_i) In aAir value (A)_i) And/or fuel value (F)_i) And an auxiliary value (H)_i) On the basis of (A), a new output value (P) is determined_i ^*) And used to adjust or re-fix the characteristic.

9. Method according to any of claims 1 to 6, characterized in that the given output value (P) is approached exclusively along the characteristic curve that has been set_i) Determining a new air value (A) by resetting the defined exhaust gas value_i ^*) And/or fuel value (F)_i ^*) Or an auxiliary value (H)_i ^*) Said new air value (A)_i ^*) And/or fuel value (F)_i ^*) Or an auxiliary value (H)_i ^*) For determining a new output value (P)_i ^*) And adjusting or resetting the characteristic curve.

10. A method according to any one of the preceding claims, characterized in that the air, fuel or auxiliary control element is changed by a respectively predetermined ramp speed.

11. Method according to claim 10, characterized in that the drives of the air, fuel or auxiliary control elements have different ramp speeds, and that the air flow and/or fuel flow and/or the auxiliary drive changes at a speed corresponding to the gradient of the respective characteristic curve when the output (P) changes.