DE3441376C1 - Process for apparatus diagnosis of the operating state of a furnace and device therefor - Google Patents

Description

- the oxygen content (O ₂ opt) in the flue gas,

- the difference between the air inlet and flue gas temperature (A dorr) -,

- the loss through sensible heat (q _A mrr) ™ flue gas,

and the instantaneous oxygen content (O ₂ ) in the flue gas, the instantaneous difference (A d) between said temperatures and the instantaneous loss due to sensible heat (q _AF ) are used as instantaneous operating variables.

4. The method according to claim 3, characterized in that at least one further size, such as carbon monoxide (CO) -, the content of CH compounds or the soot number in the flue gas in the Determination of the target operating parameters taken into account and saved.

5. The method according to any one of claims 1 to 4, characterized in that one derives the total exhaust gas losses (q _A ) from the specific target operating variables and the recorded instantaneous operating variables and stores them as a further target operating variable.

6. The method according to any one of claims 1 to 5, characterized in that from the difference between the instantaneous (q _AF ; q _A ) and target loss value (Qafopt'i qAOPr) the instantaneous value of possible relative fuel savings (A b) certainly.

7. The method according to any one of claims 1 to 6, characterized in that one continuously forms suitably defined mean values of certain instantaneous operating variables (q _AF , q _A ) and using the correspondingly averaged, stored target operating variables (q _AFO w> q _A opr) ^m Relationship brings.

8. The method according to any one of claims 1 to 7, characterized in that target operating parameters as a function of the load level (ß) with the help of at least one adjustable function generator with a load level-dependent input signal and a target operating parameters proportional output signal is stored in analog form.

9. The method according to any one of claims 1 to 8, characterized in that target operating parameters digitally stored depending on the load level and the stored operating variable values as a function of the current load level according to assigned load level values for further processing retrieves.

10. Device for carrying out the method according to one of claims 1 to 9, for a furnace system, in which sensors are provided for measuring instantaneous operating variables, with an evaluation unit for generating displays about the operating state of the system, characterized in that Storage means (19, 23, 27, 66) are provided for storing target operating variables (q _A on; A θιορτ) of the system as a function of an independent operating variable (ß) and the evaluation unit (29, 34-38, 40-46 ) is connected on the input side to inputs for the sensors and to the output side of the storage means and on the output side acts on displays.

11. Apparatus according to claim 10, characterized in that the storage means are adjustable function generators (66) and / or digital memories.

12. Apparatus according to claim 10 or 11, characterized in that a on the storage means Input for a signal proportional to the load level as an independent operating variable and at least an input is provided for at least one dependent operating variable and that dependent operating variable values assigned to these with load level values can be saved and the corresponding signals can be generated by applying corresponding, load-dependent signals dependent farm variable values are available.

The present invention is based on a method according to the preamble of claim 1 and comprises a device for this purpose according to the preamble of claim 10.

Such methods and devices are known. This is done by monitoring current operating variables The current operating status of the combustion system can be seen through displays without reference made. So is z. B. a loss report on a combustion system is not very meaningful, if not the minimal one achievable losses at all, taking into account a goal such as minimum long-term costs or minimum fuel consumption, known and related to the display. A referenceless one The display is further disadvantageous as an operator has in-depth knowledge of the system, and the processes taking place in it must have in order to interpret the displays generated in this way at all. Furthermore, the interpretation of a displayed current operating state with regard to the possible achievement of an optimal or target operating state for an operator in particular then high requirements if one of several company parameters has been set in your company

System, the readings must first be combined accordingly in order to draw conclusions to be able to intervene in the system in order to achieve the target operating status.

The aim of the invention as set out in claim 1 is to provide a method and a device as mentioned in the introduction Art to create, with the help of which displays related to a target operating state of the system are generated, with which an operator about the deviation of the current operating state from a target operating state of the system is informed. When solving this task, it must be taken into account that a combustion system per se is not in an optimal operating state, e.g. B. has minimal losses, rather, the respective optimal operating state is an operating function.

In the case of combustion systems, the target operating parameters are preferably determined on the basis of measurements. The target operating parameters mentioned for the load level range that occurs in practice are therefore only available saved.

The current operating status of the system at the current load level is then given by Relation of the current operating parameters with the previously saved target operating parameters diagnosed at the current load level.

Since, according to what has been said, it is of great importance for the correct interpretation of the current operating status of a system to know how the target operating status has been defined, how a possible target operating status is determined in a combustion system is already described at this point . The target operating condition for the combustion system is the minimization of the exhaust gas losses q _A , which is known to be composed of the exhaust gas losses through sensible heat q _AF and the exhaust gas losses through unburned matter q _AU . A first load level value ß \ is now specified on the combustion system with an optimally clean boiler. The oxygen content O ₂ in the flue gas and the carbon monoxide CO content in the flue gas are measured, as is the temperature difference AB between the fresh air supply and the flue gas. The air factor λ as a function of the oxygen content O ₂ and the carbon monoxide content CO is determined with these measured variables, as is the exhaust gas losses due to unburned material. Instead of or in addition to the CO content, the content of CH compounds in the flue gas or the soot number can also be used. On the other hand, the exhaust gas losses due to sensible heat are determined from the measured temperature difference and the measured oxygen content, depending on the fuel. The approximated determination formulas for incineration plants are known; for example, see Dubbels Taschenbuch für den Maschinenbau, Vol. II,

Section: Steam generating systems

grasslands. It is now known that as a function of the air factor Λ, determined as the ratio of the actual combustion air volume to the stoichiometric air volume, the losses due to sensible heat increase approximately linearly, starting at λ = 1 from a minimal, but not negligible loss value, and that the exhaust gas losses due to unburned material are very high in the case of a lack of air Q <1), with increasing λ falling steeply and asymptotically approaching the zero loss axis with further increasing! The superposition of these two function profiles results in a curve that initially falls steeply with increasing λ , which asymptotically approaches the linearly increasing profile of the losses due to sensible heat after passing through a minimum point. The minimum losses occur at the air factor value at which the tangent to the sum function is horizontal. The air factor assigned to the minimum value of the losses is always slightly larger than 1. Taking this into account, the combustion system to be measured is now at a certain load level ß _x by changing the air supply and thus the oxygen content O ₂ in the flue gas, thus the air factor λ, and below repeated determination - from O ₂ , CO and A ö measurement - of the total exhaust gas losses, as the sum of the above-mentioned losses through sensible heat and unburned matter, the minimum value for the total losses sought. On the one hand, this results in the target oxygen content O ₂₀ P ₇ -, the target temperature difference A d ₀ PT and, if to be included for a further evaluation, the optimal exhaust gas _losses q A0Fr or Qafopti Qauopt- Sind, which are to be stored, on the one hand If these values are found at the above-mentioned set ß \ , the system moves on to the next load level value ßi and the process is repeated, etc. For such a determination of the target operating state, other optimization criteria can also be selected, for example the minimization of the system operating costs, taking maintenance into account -, cleaning and replacement costs. Taking into account that operating parameters in a combustion system depend in a complex, not easily manageable manner on the position of the intervention means, it is now proposed that by correlating instantaneous and target operating parameters, displays, such as instructions, for correcting the setting of the Intervention means, such as the air supply, are generated to transfer the system from an undesired momentary operating state to the target operating state.

There are minimal configuration of the invention Method at least the following variables both once as target operating variables and then determined during operation as momentary operating variables as a function of the load level:

45 - the oxygen content in the flue gas O ₂ , the difference between the air inlet and flue gas temperature A d _A ,

the flue gas loss due to sensible heat in the flue gas q _AF .

The target operating parameters are saved.

In connection with a further embodiment of the method according to the invention, in addition to the operating parameters mentioned in the minimum configuration, other operating parameters such as CO content, CH compounds or soot number are recorded and their target values, depending on the degree of load β, are stored. In addition to the losses through sensible heat q _AF , the losses through unburned matter q _AU and consequently the total exhaust gas losses q _A can be determined and their target values can be stored as a function of β. A more refined display of the relative instantaneous loss components is thus also possible by means of an assigned comparison. In addition, the detection of a further variable, such as the CO content, in the determination of the target variable as well as the instantaneous variable, provides an instrument to ensure a more reliable indication of a lack of air than is only indicated on the basis of the measured values of A d and O ₂ alone.

approaching is possible. This also makes a distinction between false air entry and disrupted air Air distribution in the furnace is possible.

The storage of the target operating parameters as a function of the load level is carried out when executing the method in analog technology with the help of at least one adjustable function generator to which a load level-dependent input signal is fed and which is set so that it emits a signal on the output side depending on the input signal that the respective Target farm size is proportional. According to the example mentioned, a function generator for the optimal temperature difference A d _O pT is set so that the output signal, like the measured A (9 _{0 /) 7} function, varies as a function of the applied load level signal to determine the target size.

When the method is carried out digitally, the functions mentioned are recorded by means of table-like storage of assigned load level and operating variable values. If it is desired to provide information about the long-term behavior of a system, it is proposed that suitably defined time averages of particularly interesting variables, especially the possible relative fuel savings Ab = q _A -q _{AO, be} tested.

So the appropriate time average can be the avoidable Losses are formed from:

away

i Σ ßi (q _Ai -

/ Σ Α

30th

where / is proportional to time.

From this it can be seen that optimal values are stored during the evaluation with a given time cycle can be called up depending on the load level, and compared with the current one, then the one with the Instantaneous load level weighted average is determined. This is particularly due to the losses - total or through sensible warmth - to be applied. Since this averaging can be useful over long periods of time, it is preferably implemented digitally.

A device for the apparatus diagnosis of the operating status of a combustion system with sensors for Measurement of momentary operating variables are provided and with an evaluation unit for generation of displays about the operating status of the system, such as for the execution of the procedures mentioned according to the wording of claim 10.

Advantageous further developments are, concerning the method, in claims 2 to 9, and concerning the device specified in claims 11 and 12.

An exemplary embodiment of the invention will then be explained with reference to FIGS. 1 a to 2. It shows

Fig. 1 a is a block diagram of a system, here one Firing system, with a first part of the device according to the invention, in particular for storing Target farm sizes,

Fig. 1b as a continuation of Fig. 1a shows a second part of the device according to the invention with the evaluation previously recorded target operating parameters and currently recorded operating parameters and with the corresponding Generation of interpreted and related advertisements,

2 shows the block diagram of an analog function generator as it is generally used in an analog implementation of the device according to FIG. 1 a can be used.

In Fig. 1 a and 1 b, this is an introductory remark, signals corresponding to physical quantities and their signal paths are also denoted by symbolic abbreviations for the corresponding physical quantities, for reasons of clarity. It is in Fig. La a combustion system, not the subject of the present invention, denoted by 1. At an actuator 3, the fuel supply B _{n is set} on an actuator 5, the air supply on the one hand depending on the load level - ^ - setting on a signal generator 7 via a control 6, on the other hand also independently of one another, as shown at 3 α and 5 α . The actuators 3, 5, 7 are designed according to the size to be set, so the actuator 3 as a fuel valve, the actuator 5 as an air flap. With a signal converter 9, the z. B. as the angle of rotation of a steering wheel entered momentary load level β converted into a corresponding electrical signal, with a sensor 11 the temperature of the inlet air δ _σ , with a sensor 13 the temperature d _{A of} the flue gases, with a sensor 15 the oxygen content O ₂ in the flue gas, with a sensor 16 the CO content in the flue gas. In a first process step, the system is now generally operated optimally under optimal conditions. In the case of a combustion system, this means that the system is operated with a variation in load level β in the load level range that occurs in practice with freshly cleaned heating surfaces and under nominal conditions (type of fuel, boiler pressure, etc.) and the desired target operating conditions are set on the combustion system .

As already explained in the introduction, the target operating conditions are now recorded as follows.

Initially, the input switches S are closed. A fixed degree of load βχ is set and recorded at the signal converter 9. The measured temperature values du for the fresh air and d _A for the flue gas are offset in a subtraction unit 21 to form the temperature difference Ad. At the output of the sensor 15 the measurement signal for the O ₂ content appears, at the output of the sensor 16 for the flue gas CO content. The oxygen content measured value and the temperature difference measured value, as well as the CO measured value, are fed to a computing unit 25. In the arithmetic unit 25, the exhaust gas loss q _{A is} determined, taking into account both the exhaust gas losses due to sensible heat q _AF> and the exhaust gas losses due to unburned material q _AU , because a minimum can only be determined when both components are taken into account Target operation of the system is an operation with minimal exhaust gas losses is essential. In this case, the CO content must be taken into account. The arithmetic unit 25 determines the shape according to a known expression

CO

At ₁ -O ₂

the exhaust gas losses due to unburned material, according to
Ad

Qaf

Ar ₂ -O ₂

the exhaust gas losses due to sensible heat and, through addition, the total exhaust gas losses q _A (O ₂ , A d, CO). These expressions with the introduction of corresponding proportionality constants are either analog in the sense of analog programming or digital

calculated. The evaluation of (1) for the optimum determination can, if only ^^ evaluated afterwards will be done manually.

By preferably adjusting the air supply at the actuator 5a, the total exhaust gas loss values determined are minimized. The corresponding electrical signal value appears at the output of the arithmetic unit 25 and is monitored. If a minimum has been found, which is possible automatically by means of a minimum detection network 17 or else by reading, a charging signal 1 is triggered. This charging signal L is fed to a first memory 19, to which the oxygen content O ₂ and the degree of load β are fed on the input side. When the charging signal L appears , the value of the load level β and the optimal oxygen content _{value O 2} opt (A) are stored. The charging signal is simultaneously fed to a memory 23, which in turn is fed the load level signal β and the temperature difference signal A δ . Here, too, when the charging signal L appears, the load level value β and the corresponding temperature difference value A δ _Ο ρτ (Λ) are stored. The output of the arithmetic unit 25 observed for finding the minimum exhaust gas loss is stored in a further memory 27 together with the load level value β when the charging signal appears. This determination process for the target operating parameters is repeated for further load level values within the operating load level range of the combustion system 1 until the load level-dependent functions of the operating parameters recorded there are stored as optimal values or target values in the memory 19, 23, 27. Then the switches S are opened, the memory contents are not changed any further and are available for subsequent evaluation at the corresponding outputs. When the system is now operated, the following information is available:

With the current load factor β set , the following appear at the memory outputs:

40 - the target exhaust gas loss value at memory 27

- At the output of the memory 23, the target temperature difference as a function of the degree _{of load, Αδ Ο} ρτ (Λ) and

- at the output of the memory 19 the target oxygen content O ₂ often (M,

as well as the measured values as momentary operating variables:

50

- Load factor β for the memory retrieval

- the current temperature difference A d

- the current flue gas oxygen content O ₂

- If necessary, the current CO content of the flue gases (dashed).

The momentary exhaust gas losses q _{A also} appear during system operation at the output of the arithmetic unit 25, which, however, is then separated from the memory 27. In a less complex configuration, only the losses through sensible heat q _AF are determined as instantaneous losses from the instantaneous O ₂ and A ^ measured values, with a more complex q _A as the sum of the components q _AF , q _AU , as shown in dashed lines, with instantaneous value measurement of CO. According to FIG. 1 b, the current exhaust gas loss value q _AF (β) or q _A (β) is continuously compared in a first comparison unit 29 with the loss value qAoiT ^ ßm) ^{at the} output of the memory 27 corresponding to the then current load level β _m. The comparison result Ab is used to control a display 31, which indicates a possible fuel saving, and possibly an assigned instruction display 32, which instructs to change the fuel-air ratio. The instantaneous exhaust gas losses corresponding to q _AF (β _m ) or q _A (/? “,) Are displayed on a display 33. At comparison units 34, 36, 38, to which on the one hand the target temperature difference _values A d 0PT (ß _m ) are fed from the output of the memory 23, and on the other hand the current temperature difference values Ad (ß _m ) , the current temperature difference values are compared with the target difference values and determined whether the deviations of the temperature differences are within predetermined ranges or not. Analogously, comparison units 40 to 46, to which the target oxygen content from memory 19 at the current load level ß _m and the current oxygen content _{values O 2} (ß _m ) are fed, are used to check whether the current oxygen values O ₂ (ß _m ) are referenced to the target oxygen content _{values O 2} 0PT (ß _m ) lie in the specified ranges.

From the logical combination of the outputs of the comparison units 34 to 38 on the one hand, and 40 to 46 on the other hand, the boiler contamination is displayed on a display 54, if necessary with instruction 56 to clean the boiler, on a display 52 that false air is being supplied, on a display 48, that there is an excessive excess of air and at most on a display 50 that the air supply is to be throttled. Checking the instantaneous oxygen content O ₂ (ßm) with reference to the target oxygen content O ₂ opriss ™) alone gives the indication on a display 58 that there is a lack of air, which can trigger a danger or alarm signal. Accordingly, a display 60 can be activated which gives the instruction to increase the air supply.

If, when the target operating parameters are saved, not only the total flue gas loss q _A opr is saved, but also (not shown) according to the expressions (1), (2) its individual components QAFOPT-, QAUOPT due to unburned or sensible heat, see above there is the possibility of outputting both components separately, even during system operation, as a function of the current load level at the output of the arithmetic unit 25 and then comparing them with the loss components q _AF (ßm), q _AU (ßm) then each individually determined. This provides information on deviations in the current exhaust gas losses, separated into losses through sensible heat and losses through unburned material, with reference to the optimum values. If, as mentioned, the CO sensor 16 is dispensed with in the acquisition of the instantaneous values, the arithmetic unit 25 will determine the instantaneous flue gas loss, ignoring the losses due to unburned matter, which, however, is sufficient in many cases. It must be repeated that in this case the CO measurement is only necessary to find the minimum loss. If the CO measured values are also stored as CO _0W ~ values as target variables, the possibility arises from comparing these target CO values C0 _OPT (ßm) with the instantaneous CO values CO (ßm) measured during operation for uneven air distribution to close, as well as to make the air deficiency diagnosis more reliable.

Furthermore, in some cases it can be advantageous to use suitably defined time averages of

To determine operating parameters continuously. This generally assumes that the system for executing the method is digital. A clock generator 64 is then provided in the usual way, which clocks the memory and sensor outputs during the evaluation, as on a microprocessor-based unit. If averaging is dispensed with, it is sufficient in some cases to set up such an arrangement on an analog basis. The memories corresponding to 19, 23 and 27 of FIG. 1 a are then implemented, for example, by function generators, as shown in FIG. Function generators emit an output signal as a specific function of an input signal. The function generator 66 shows a possible form of implementation with a diode resistor network. When the target operating parameters / load level function is stored, the latter is first determined graphically, for example, and then by adjusting the potentiometer 2? _u tos A ₃₂ at most from bias sources V _x to F ₃ , by piecewise linearization, the determined function curve, for example set for the temperature difference Ad (ß) , as a function of the load level-corresponding signal U (ß) at the input of the function generator.

For this purpose 3 sheets of drawings

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Claims (3)

Patent claims: 1. A method for the apparatus-based diagnosis of the operating state of a combustion system, in which instantaneous operating variables of the system are recorded and indications for the operating state are generated therefrom, characterized in that target operating variables (A d _0PT , 0 ₂ opt) of the system are previously in function of the degree of load (ß) is determined and, if necessary, with the target operating parameters derived therefrom (q _AO pr \ as a function of the degree of load (ß) are stored and displays (31, 48, 52, 58) of deviations by relating current to target operating parameters of the current operating state generated by the respective target operating state. 2. The method according to claim 1, wherein intervention means (3 _a , 5 ") are provided on the system for influencing the operating state, characterized in that by relating momentary to target operating variables (Ad, O ₂ ) displays ( 50,56,60), such as instructions for correcting the setting of the intervention means (3 _a , 5 _O ) generated to transfer the system from an undesired momentary operating state to the target operating state. 3. The method according to claim 1 or 2, characterized in that the target operating variables are at least determined and stored as a function of the load level (ß):